J^flhfis 
 ^rmtkjDaw5(ni7ldam5 
 
The following “ Memoirs ” have been 
 printed verbatim from the manuscripts of the late 
 Mr. Mac Culloch, without note or comment. His 
 sudden and lamented death has prevented my 
 remarking on certain of his opinions and state- 
 ments ; but these, it is hoped, will be received as 
 he meant them to be, by such as are competent 
 judges of the real errors and deficiencies in the 
 unfortunate Map, that became so fertile a source 
 of his indignation. 
 
 5. A. 
 
2 
 
 Memoirs to H. M. Treasury respecting the 
 
 EXPLANATIONS 
 
 respecting the 
 
 GEOLOGICAL MAP OF SCOTLAND, 
 
 AS NOW PRESENTED TO THE TREASURY IN THE BEST STATE 
 WHICH THE CIRCUMSTANCES PERMITTED. 
 
 THE Map chosen for the purpose of recording the nature, 
 extent and boundaries of the Rocks of Scotland, being the object 
 of this Survey, is that of Arrowsmith, since there is no other in 
 existence uniting a sufficient size with equal detail. Even this 
 size, being on a scale of a quarter of an inch to a mile, is inade- 
 quate to the representation of the smaller tracts, where many 
 different rocks occur in approximation, and to that of those 
 rocks, such as primary limestone, which occupy very narrow 
 lines in nature ; as I shall explain more fully in speaking of the 
 
 colouring hereafter. . r i 
 
 But if a much larger Map would be desirable for the purposes 
 of such a survey and record, there are countervailing objections, 
 arising from the expense, and from the unwieldiness of one of 
 materially larger dimensions. The nlere doubling of the scale of 
 this, would, it is evident, demand sixteen sheets of paper where 
 there are now four ; while a scale, intermediate between a half 
 and a quarter of an inch to the mile, would not be attended by 
 any material accession of advantage. 
 
 A greater objection, however, to an enlarged Map, at present, 
 consists in the want of accurate materials for such a work. The 
 inaccuracy of the present one is so veiy great, that it would be 
 to render error more striking, and to waste money, were it to be 
 re-engraved on a larger scale. It is true, that it might be cor- 
 rected in many places, from some of the more recent county 
 maps and private surveys, and thus rendered less erroneous than 
 at present. But it would still be a work of errors. If some of 
 these newer county maps are of a very respectable accuracy, this 
 is not the case with the whole : while, of every one, I believe, 
 I may say, that the forms of the ground, so indispensable to an 
 accurate geological survey, and to the production of a corres- 
 ponding map, are laid down in so false or unintelligible a man- 
 ner, that it would be idle to copy them, and impossible to reform 
 them. If there is any one among them so tolerable as to admit 
 of such reform by a practised surveyor and able draughtsman, 
 
3 
 
 Geological Map of Scotland. 
 
 there would even then be little gained ; since the greater number 
 are quite absurd, and since there is but little correspondence be- 
 tween those which have been executed at very distant periods, 
 and by different surveyors, generally careless as irresponsible, 
 and every one taking his own peculiar views, and adopting his 
 own conventional method of representing ground. But, under 
 any consideration, I know not who is likely to execute such a 
 work of labour and expense as a new compilation of a Map of 
 Scotland. No publisher would undertake it, under the double 
 obstacle, of the present Map, and of the prospect of an accu- 
 rate one from the hands of Government ; while Government, of 
 course, would not bestow expense on so bad a subject, especi- 
 ally for so limited a purpose as the present, when it has already 
 commenced a regular survey of Scotland, in Conformity to that 
 of England. 
 
 But be all this as it may, there was no resource left to me, 
 but to take the Map as I found it, to use it in the investigation 
 of the ground, and also to adopt it as the draught on which to 
 record the rocks as they were ascertained. When I first com- 
 menced there were but few of £ven the present county maps ; 
 so that any corrections from such sources were impracticable. 
 As they continued to appear, sometimes offering useful correc- 
 tions, it often proved that the geological work had been already 
 done by me, and entered on the present general Map ; so that 
 although it was seen to be inaccurate, from the inaccuracy of 
 the Map, it could not be corrected without a fresh survey of the 
 ground under the guidance of the new county map ; a proceed- 
 ing for which no time could be allowed, as it would also have 
 been to prolong the work to scarcely a prospect of any termi- 
 nation. 
 
 If it is thought that the better class of county maps might 
 have been used in the work, or at least in correcting the errors 
 of the general one, it was not for want of many attempts that 
 I was obliged to abandon all hopes of this nature. Portions of 
 surveys were made on county maps ; as all of them nearly were 
 used in the actual surveying, for the purpose, or with the hope, 
 of more certainly assigning the surveyor’s place, and the features 
 of the country. But the want of conformity and fitting between 
 the works of different surveyors, sometimes in the scales, at 
 others in the accuracy, and, at others again, in the mode of 
 drawing and engraving, rendered it quite impracticable to enter 
 a consistent geological survey on two of these Maps, or to con- 
 tinue a given tract of rock from one county to the conterminous 
 one. Even where this might have been partially done, it be- 
 came impossible to transfer the larger-scaled survey thus exe- 
 cuted, to the general Map : so extraordinary and frequent were 
 the discrepancies between this compilation of Arrowsmith’s and 
 the surveys of these more recent surveyors. Even passing by 
 all these objections, the unwieldy magnitude of an extensive 
 collection, or of that number of those large county maps which 
 
 B 2 
 
4 Memoirs to H. M. Treasury respecting the 
 
 must have been carried about, generally in the pocket or on the 
 person, in consequence of the many counties which were otten 
 examined, to a greater or less extent, m the saine season, would 
 have rendered the use of these impossible ; and far more so, when 
 it must be recollected, that every map must have been used in 
 the open field, perhaps a hundred times in a day, and in all kinds 
 of weather, frequently in rain, so as to render unmanageable a 
 laro'er piece of paper than could be sheltered under an umbrella; 
 without which precaution a few minutes might have effaced the 
 work of many weeks, or of a whole season. Hence, however 
 occasionally useful these county maps proved, m the manner 
 already noticed, that utility was compulsorily limited to the 
 
 might be'^thoUght, by those who have not considered this 
 subject, that a substitute might have been found by re-drawing 
 these maps, or the most needful and correct of them, in a con- 
 nected or a continuous manner, to one common scale, and on 
 one of inferior magnitude and more convenience. Hut while 
 such a work would have required the labour of regular draughts- 
 men, of an establishment, in reality, superadded to that ot the 
 mere geological surveyor, when the comparisons, the adapta- 
 tions, the reductions, and even the mere labour of the work, are 
 
 considered, such a work would not then have answered all the 
 necessary purposes, unless as many copies could have been tur- 
 nished as the geological surveyor might have called tor. Ine 
 wear of maps is unavoidable, under the frequent use ot them 
 already alluded to ; under the friction which they must undergo 
 in the pocket or otherwise, especially at the foldings and angles^ 
 and under the inevitable exposure to rain, or to the wet clothes 
 of the surveyor. Thence a frequent renovation, of parts at least, 
 is necessary : so that nothing but an engraved plate, capable of 
 furnishing many impressions, would have answered the pur- 
 pose : while I need not repeat the objections to such an attempt 
 as this. 
 
 Thus do the reasons appear why I was condemned to the use 
 of Arrowsmith’s iVl ap ; inaccurate as I daily found it to be, as 
 well in the political as in the physical geography, and greatly as 
 these inaccuracies continued to increase on my hands as I be- 
 came better acquainted with the country : to say nothing of the 
 great inconvenience, difficulty, and obscurity, which I have else- 
 where noticed as arising from the blackness of the engraving, 
 in confusing or rendering doubtful many of the colours applied 
 to the distinctions of the rocks. 
 
 These reasons for the proceeding here adopted, which are due 
 to the Government that directed this work, ought also equally 
 to satisfy those who may consult this Survey ; unless, indeed, it 
 be such persons as seek for a ground of censure in the non- 
 performance of impossibilities. But let it at the same time be 
 understood, that these unavoidable explanations are the sole 
 reasons for the criticism and consequent censure often here be- 
 
5 
 
 Geological Map of Scotland. 
 
 stowed on the Map in question, since it is with great unwilling- 
 ness that I have said aught which may depreciate the value of 
 a tradesman’s property, to which, after all, recourse must be 
 had, in some manner, for the object of publication. 
 
 But where there was known inaccuracy in this Geological 
 Survey, of which I shall hereafter point out examples, it was not 
 just that the geological surveyor should be blamed for faults 
 not his own; as, without this explanation. His Majesty’s Go- 
 vernment might have equally seemed to deserve blame for the 
 choice of an incompetent person. The faults actually exist in 
 the Geological Survey, as I know far better than any other per- 
 son, or any hundred persons are ever likely to do: but those faults 
 lie in the Geographical Draught, and he who has committed 
 them is the person who ought to bear the blame ; as even he 
 cannot expect that the surveyor, who has already suffered most 
 deeply by them, is to bear them for him. 
 
 1 must now add, that it was found necessary to make some 
 additions to this Map, in replacement of omissions and errors ; 
 with respect to which I must here make the following remarks : 
 
 The rocks called Stack and Skerry, lying to the north of the 
 Sutherland coast, are omitted in Arrowsmith ; but I have not 
 added them, though I examined them as wishing to leave no 
 blot in this work ; because they do not seem to justify the 
 extension of the printed sheet to which they belong, so far, or 
 even such an appendage as those two which I have added in 
 other places : it must suffice to say that they consist of gneiss. 
 
 The islands of Barra and Rona (North) are grievously mis- 
 placed in that Map, both in latitude and longitude ; and having 
 therefore observed for their places when I examined them, I 
 have restored them to their proper situations, in a Rider to the 
 engraved Map. 
 
 St. Kilda is omitted entirely ; nor is there even any note for 
 its place, as there is neither map nor measurement in existence. 
 I have taken its place from the Nautical Tables; and its form 
 and measurement are the result of an examination by walking 
 and a pocket compass ; inaccurate, of course, but sufficient for 
 the present purpose, as the rocks are very simple. It is also 
 appended as another Rider to the engraved Map. 
 
 It is now indispensable to make some more detailed remarks 
 on the inaccuracy of Arrowsmith’s Map, before proceeding to 
 any description of the coloured work, as an intended representa- 
 tion of the places, spaces, and boundaries of the several rocks 
 which constitute the mineral structure of Scotland. No one can 
 know this inaccuracy as it is known to me; since nothing but 
 that minute examination of the entire country which I have made, 
 and which will never again be made by one person, could detect 
 these errors. The ordinary use made of maps leads to no know- 
 ledge or criticism of this nature ; since that seldom relates to 
 more than the political geography, in which also even great er- 
 rors pass unnoticed. Thence, and from the magnitude, splendour 
 
 B 3 
 
6 Memoirs to H. M. Treasury respecting the 
 
 and reputation of this work, it is generally esteemed unexcep- 
 tionable. But should any geologist or mineral surveyor, be- 
 lieving this to be true, examine the coloured work, and compare 
 it with nature, he will find it full of errors, as to the dimensions 
 and boundaries of rocks, and will, as naturally, attribute them 
 to the geological surveyor, not to the map-maker, or the 
 rect basis which the foiWr was obliged to use as the draught for 
 his entries. If it is important to the reputation of the surveyor 
 to show where the real errors lie, and what were the causes which 
 rendered an accurate geological survey impossible on so bad a 
 basis ; so is it even more due to His Majesty’s Government, 
 which adopted part of this Survey, and ordered the remainder ; 
 lest blame should fall on them, as I have just remarked, tor an 
 improper choice, or for not doing what it is not, now, m the 
 power of any Government to effect. 
 
 This reason will also apply to the enumeration of other sources 
 of error, doubt, or imperfection, which I shall hereafter notice : 
 it being essential that no pretence be supposed, of giving out as 
 an accurate work that which is known not to be such. But it is 
 those persons alone that may have attempted such a one, who 
 know that accuracy is unattainable, and will probably ever be 
 so, under any increase of knowledge and length of labour. They 
 who are ignorant of this subject, and who may therefore have 
 formed higher expectations, ought also to be now undeceived ; 
 which I can only do by showing, together with the errors, what 
 are the sources of these, and how often they are irremediable 
 
 ones. . ^ . 1 , 1 
 
 If 1 have noted down, for my own satisfaction, all those errois 
 
 in this Map which rendered an accurate geological survey im- 
 practicable, the detail is infinitely too long for this report. The 
 enumeration of a few of the principal ones, of different kinds, 
 which I have selected as examples, both in the physical and the 
 political geography, may, I hope, suffice ; and he who will mul- 
 tiply them all, a hundredfold and more, (1 might almost say a 
 tlioiisandfold), will be in no danger of exceeding the truth ; so 
 widely does error pervade the whole of this unworthy Map. 
 
 Whatever other disgrace may attach to the actual surveyors 
 whose documents are thus compiled into this whole, it is the 
 pure fault of the compiler not to have adopted a system of pro- 
 gressive correction. But if the ancient defects in the physical 
 geography thus remain uncorrected, while they might have been 
 amended from more modern surveys, that which 1 shall first 
 notice relates to the political geography ; as it admitted of easy 
 correction, and as this class of error gives the geological surveyor 
 more trouble than all else in the actual investigation of the 
 ground, while equally depriving him of the power of laying down 
 on the map what he has examined and ascertained. 
 
 II is points and lines of reference for the places and boundaries 
 of rocks, consist partly in objects of physical, and partly in those 
 of political geography. Without these he can do nothing ; and 
 
7 
 
 Geological Map of Scotland. 
 
 in proportion to their number and truth will the work of sur- 
 veying be easy and sure, and the records accurate. Reversely, 
 defect or error in these renders the first laborious, and often im- 
 practicable ; as the latter become a mere matter of chance, and 
 as likely to be wrong as right. 
 
 in the political geography (to note this first), the objects are 
 towns, churches, houses, and so forth, together with roads ; and 
 these last are of the chief importance, since they are not only 
 the most extensive references, but are those to which any one 
 examining the work, for whatever purpose, that he may know 
 the facts in nature by means of it, will naturally refer ; as his 
 examinations will also be chiefly made from roads, in the act of 
 travelling. It is even more important to recollect that they form 
 the chief basis of the surveyor's operations. He is not indeed 
 confined to roads, but he must make a principal use of them ; 
 as by them he will ascertain most frequently what object or 
 ground in nature finds its correspondent mark and place in his 
 map. And similarly, it is by referring the places of the rocks in 
 nature to such roads, that he will find the best, and often the 
 only means of noting those places on the map. I need not say 
 that a record of rocks by any mode of triangulation or measure- 
 ment would be impracticable, by at least less labour than a geo- 
 graphical survey would demand, — the labour of many men and 
 many years ; while, though executed, it would be purposeless, 
 unless it referred to and coincided with that geographical survey 
 by which all future observers will be guided in their studies or 
 inquiries. 
 
 Now it has happened in Scotland, that entire new systems of 
 roads have been constructed all over the country, since this Map 
 was compiled, while many of the old ones have been abandoned. 
 If these new roads are sometimes found where no road ever was 
 before, it is evident that they at least furnish no assistance, if 
 they produce no positive evil ; since there are no means of ascer- 
 taining on this Map whereabout they lie. But the most insur- 
 mountable difficulties, with consequent incorrigible errors, arise 
 where the new roads lie near the old ones ; deviating from them, 
 or interspersed among them. The surveyor thus sees a road in 
 the Map, which he believes to be the one he is on ; not finding 
 till too late, or perhaps never discovering at all, that they are 
 miles asunder; in consequence of which his entries are made in 
 a wrong place, with a frequent consequent production of grievous 
 errors, or of a confusion which he has afterwards no time to 
 remedy. And thence also, amid this misplacement, and from the 
 want of correspondence between the actual roads and those in 
 the Map, does the physical geography become so confused or 
 unintelligible, that he cannot make out what it is, nor conjecture 
 where to seek it on the Map; since no portion of it but what 
 consists in rivers and lakes and sea-shores is given with even 
 tolerable truth. These also are of far too rare occurrence, com- 
 pared to the total extent, to offer much assistance, considering 
 
8 Memoirs to H. M. Treasury respecting the 
 
 the innumerable wants of this nature : while the representations 
 of the ground, instead of giving any aid, are generally so false as 
 to assist in misleading him. 
 
 If this source of difficulty and error is nearly universal, so is 
 it true that the incorrect manner in which the roads actually 
 drawn, are placed, leads to frequent similar errors and difficul- 
 ties. In nature, the boundary of a tract of rock will bear a cer- 
 tain relation, first, to a river or other circumstance in the physical 
 geography, and next, to a road entered on the Map. But this last 
 entry being inaccurate, the rock, as delineated on the draught, 
 cannot be brought into a true relation to both ; and it has thus 
 turned out that the boundaries of the rocks, in many different 
 places, as I have been compelled to lay them down, cannot be 
 made to reconcile with anything ; for the obvious reason, that 
 the two kinds of geography, the physical and the political, are 
 irreconcileable. 
 
 It is plain, therefore, that in all these cases, he who attempts 
 to investigate the country with the Map in his hand, will find 
 himself at a loss, or suppose error on the part of the surveyor, 
 where the real error is in the Map itself. If he examines from 
 a road, it may be a different one from that used by the surveyor ; 
 or he may make the same species of mistake, by referring to the 
 road which he sees on the Map, when he is, in fact, in a far 
 different place : or, reversely, if he examines by the physical 
 geography, that which the surveyor has referred to a road, he 
 will equally suppose the latter in error \ unaware of the circum- 
 stances which 1 have thus noticed. 
 
 This is but a slender sketch of the nature of these sources of 
 difficulty, and of error, real or apparent ; it would be tedious to 
 state them more fully. Jt would be still more so to point out 
 the facts themselves on the Map, as a statement of its errors 
 would occupy no small volume. Two examples must suffice: 
 they will be specimens of what will be found everywhere, by 
 him who shall pursue the comparison of this Map with the 
 ground in nature ; as I might myself have added hundreds of 
 similar ones. 
 
 The road between Ayr and Dalmellington is accompanied by 
 a river, for some space,\hrough a very marked valley, where the 
 several boundaries of red sandstone, coal, and trap, lie. The 
 river or the road form the best references for these different and 
 most important boundaries; as the ground might have done 
 had it been well laid down, since it is very strongly characterized. 
 But the road is so extremely incorrect, that a reference to the 
 river causes the boundaries to bear a relation to the road, which 
 any one, going along it, will see to be false ; while, if it is at- 
 tempted to prevent this by referring to the road, then the same 
 falsity of entry takes place as to the river. 
 
 Of the error or confusion which may occur by mistaking a 
 new road for an old one, or by referring to the map road that 
 which has been examined by the road in actual use, a case near 
 
9 
 
 Geological Map of Scotland. 
 
 Pennycuik will afford a sufficient example. Here, the boundary 
 of the slate and the coal series is very accurately defined by the 
 old road to Peebles ; but this having been replaced by a new 
 one at a little distance, is abandoned, while it is the only one in 
 the Map. He who travels the new road does not perceive this ; 
 and thence, on inspecting the coloured Map, he will imagine 
 a gross error, in having placed a boundary of slate where he 
 cannot see it. 
 
 If these and similar facts might be multiplied without end, it 
 is also unfortunate for the apparent accuracy, or repute, of the 
 work, that the most numerous changes of this nature occur in 
 the most intricate and interesting parts of the country ; as they 
 do also in those which, from their populousness and value, are 
 most likely to be the subjects of examination. Among these I 
 may name Fife, where, from the inaccuracy, defect, addition, 
 and misplacement of roads, added to the gross errors in distances, 
 to the utterly false or absurd representation of the physical geo- 
 graphy, and to the intricacy of the country itself, both on this 
 point and in the disposition of its rocks, it becomes utterly im- 
 possible to give on the Map a true representation of that which, 
 in itself, offers no difficulty whatever. 
 
 Of the whole of Scotland, indeed, I may say generally, that 
 whatever the personal labour and the ordinary difficulties of 
 travelling through such a country as much of it presents, may 
 be, there is extremely little obscurity either in the disposition 
 or the boundaries of its rocks ; as, for the greater part, nothing 
 can be more clear and satisfactory to the geological surveyor 
 than the structure of the country. With an accurate Map, 
 therefore, there would be no difficulty in giving a very true geo- 
 logical survey ; and it is scarcely possible, therefore, to describe 
 the mortification which is felt, from finding that all this know- 
 ledge is wasted, since it cannot be recorded ; or in similarly dis- 
 covering that it must be falsified in some manner or other, if it 
 is to be brought into any tolerable coincidence with that false 
 geography which the Map represents. Let the vexations, fatigues, 
 privations, or absolute sufferings have been what they may, the 
 whole united have been far exceeded by the mixture of never- 
 ending anxiety, disappointment, and mortification proceeding 
 from this single cause. 
 
 The other errors in the political geography of this Map, arising 
 similarly, more from its antiquity than any other cause, are of 
 less moment than those which relate to the roads : yet they are 
 often sufficiently troublesome to prove great sources of confusion 
 and error, both in the examination itself, and in the entries on 
 the geological Map ; while, in a similar manner, the attempts to 
 verify the present work on the ground, will ofthn lead to the 
 supposition of error, even where the boundaries are correctly 
 given, but where they have been laid down under a different 
 reference from that which the verifier may have supposed. 
 
10 Memoirs to H. M. Treasury respecting the 
 
 This Map is very laudably filled with names of petty villages 
 and houses, and nothing can be more desirable than this to him 
 who wishes to give an accurate geological survey : since it not 
 only facilitates references, but renders the woik more useful, by 
 the accurate definition of boundaries. And as it is also a test ot 
 truth it is especially desirable to him who knows that his work 
 is accurate : while he who omits such points in his geological 
 maps when he might have possessed or introduced them, is 
 conscious that his work will not bear examination ; or is giving 
 a general, and often a conjectoal sketch, rather than a work 
 deserving the name of a geological map. 
 
 But the immense increase of population, with the enormous 
 extent of new cultivation in Scotland since this Map was com- 
 piled, has produced the most extraordinary discrepancy between 
 the actual state of the country with respect to houses and vil- 
 lages, and that which is represented on it. Farms, which 
 appear important references in this geographical work, have 
 vanished, or have become so insignificant that they cannot be 
 found, their names being forgotten by the country people, to 
 whom we must refer as gudies for this purpose : while if many 
 have been transferred, under the same name, to new situations, 
 there are thousands, in every part of the country, being also the 
 most conspicuous, which are without name or place in the Map. 
 The confusion and difficulty hence resulting are extreme, and often 
 perfectly inextricable ; as the consequences are similar, both in 
 the investigations and the entries, to those which arise from the 
 actual state of the roads compared to their dispositions and 
 numbers on the Map. Nor is this discrepancy true of the farm- 
 houses and petty villages alone ; since many of even the parish 
 churches are rebuilt in situations far wide of that which they held 
 when this Map was compiled, so as to aid very particularly in 
 confusing the records of the geology, and in misleading the 
 observer ; as they must hereafter mislead him who attempts to 
 verify the present work, or, as is most likely, make him believe 
 that he has discovered faults of carelessness or neglect. 
 
 To this I may also add the errors and the omissions of the 
 Map, respecting objects of this nature which were in existence 
 at the period of its compilation ; including, not only conspicuous 
 farms and manorial houses, but even ancient villages, castles, and 
 parish churchei An important parish church, important to the 
 geological surveyor, as it serves to define the course of a narrow 
 tract of red sandstone near the southern Esk, is not noticed in it. 
 In Aberdeenshire there is a road to Echt, by which a complicated 
 boundary of gneiss and granite might have been defined ; but 
 there is no road in the Map. Failing this, there is an ancient 
 castle, by which an essential part at least of that boundary 
 might have been fixed ; as, in other places, there are villages, 
 and in another again, an ancient inn. But all are equally want- 
 ing ; and as not even the forms of the ground are noted, it be- 
 
11 
 
 Geological Map of Scotland, 
 
 comes utterly impossible to know where to place on the Map 
 those rocks which there is no difficulty in ascertaining. In Fife, 
 and where a geological reference might have been found in a large 
 ancient village, there is no such place marked ; but this, and si- 
 milar things, are so true of that intricate piece of geology, that it 
 would be endless to note them. And not to extend the examples 
 of this class of error, I shall lastly content myself with pointing 
 out a large tract of country near the Dee, and extending from 
 Strahan, which the Map represents as a tract of barren, roadless, 
 uninhabited mountain land, whereas it contains villages and 
 houses beyond enumeration, with roads in abundance, all of a 
 high antiquity, and thus forming one of the most populous por- 
 tions of this county. The slightest reflection, even on the part 
 of those who are utterly ignorant of this subject, must show how 
 impossible it must be to give a true survey of this nature on a 
 basis so utterly false. For aught of resemblance between the 
 country itself, and its pretended Map, whether under physical or 
 political geography, there are many parts of it which might as 
 well pass for draughts of Africa as of Scotland. 
 
 I presume that I need not extend this class of remarks, as 
 I dare not here occupy more space with them. He who may 
 hereafter choose to examine the country by means of this Map, 
 whether he shall do it for the purposes of geology or not, will 
 soon convince himself that I have not told the least part of the 
 truth ; and, if a candid examiner, he will seldom find much 
 difficulty in explaining the source of the actual errors and appa- 
 rent mis-statements which he may discover in the geological sur- 
 vey. A great number of these, at least, are now well known 
 to myself ; and 1 once intended to have given a list of them, since 
 it was impossible to correct them without that fresh survey for 
 which time could not be allowed ; while even then but a very 
 small portion of the whole could have been corrected on the 
 Map, from its own incorrigible inaccuracy and deficiencies. But 
 I found that such a list would have proved far too long, and 
 much too difficult to verify on the Map, from the same causes ; 
 so that I must now be satisfied with this general statement, which 
 will at least serve to prove that few will hereafter find defects of 
 which I am not perfectly aware, and which I could not myself 
 have pointed out. 
 
 I must now turn to those deficiencies which belong to the 
 physical geography of the country ; errors, or falsities, or defects, 
 which alone would suffice to produce as much difficulty and 
 mis-statement as those just pointed out, but which, united to 
 them, augment these in an incalculable degree. If there was 
 truth in either, it would correct the falsity of the other in some 
 measure ; but the complication between two modes of falsity is a 
 source of confusion which no one can comprehend who has not 
 made the same attempts as myself, with the same anxiety after 
 truth. 
 
12 Memoirs to H. M. Treasury respecting the 
 
 It is partly an irremediable defect arising from the smallness 
 of the scale of the Map, and partly from the badness of the 
 surveys and dravi^ings, that tracts of complicated hilly ground 
 are not correctly expressed in it, or not expressed at all. And as 
 such complicated ground is generally the consequence of diver- 
 sities in the rocks, while there are not a sufficient number of 
 points in the political geography to which they can be referred, 
 there are no means whatever of representing on the Map that 
 which is perfectly obvious on the ground itself, and could be 
 recorded without the least difficulty on a true map. If examples 
 of this source of mis-statement occur all over Scotland, they are 
 especially remarkable in Fife, where also they are especially 
 vexatious, because it is a question between the places and boun- 
 daries of coal strata, often producing workable coal, and the trap 
 rocks which interfere with and interrupt these. But it must 
 suffice here to point out the tract which includes Burntisland and 
 Auchtertoole, in which it has proved impossible to enter on this 
 Map the several rocks as they occur on the ground, absolutely 
 defined and easy of investigation as they all are. 
 
 It is a simple error in the physical geography, to have stated 
 distances on the Map differently from what they are in nature. 
 This, sufficiently unpardonable fault in a geographical survey, is 
 of perpetual occurrence ; and though sometimes of no great 
 moment to the geological surveyor and his work, it frequently 
 leads to difficulties and doubtful entries, or to absolute mis-state- 
 ments, for which also there is no correction to be found. Where 
 political or physical points of reference are wanting, there is no 
 resource but to measure for the boundary of a given rock, from 
 some assigned point on the Map, as the nearest convenient 
 distance. But the distances of two such points being falsely 
 given, the reference which may be true for one, is not true for 
 the other. Thence a great apparent error, to him who may have 
 chosen a different point of reference from that of the geological 
 surveyor, supposing that he has adopted this method ; while if 
 he has adopted the expedient of averaging and dividing the error, 
 the examiner of the ground by means of the Map, will necessarily 
 find both references wrong. And thus also, in some cases, 
 where many rocks occur in such a space, there is not room for 
 them on the Map, if that has been made too small at this part ; 
 while, if too large, they must be displaced or magnified, that 
 something at least like a true general record may be made. 
 
 To notice an example, out of many, under each of these cases : 
 the successive boundaries of clay slate, mica slate, gneiss, and 
 granite, on the Cairney Mount line, can only be ascertained by 
 a measurement of each belt with reference to the bridge of Dye, 
 or to a more southern point ; whereas the distances on the Map 
 are so false, that the measures taken from that point, and from 
 the reverse one, entirely differ, so as to throw confusion into the 
 whole, and to compel a mere statement of the general fact. And 
 
13 
 
 Geological Map of Scotland. 
 
 near Kilbride, where many edges of limestone occur in a some- 
 what narrow tract, the same incorrectness renders it quite impos- 
 sible to place them in the situations and proportions which they 
 possess in nature. 
 
 But the defects in the physical geography of this Map are far 
 from being thus limited, while they pervade almost every part of 
 the country. The great exceptions to this are in those tracts 
 which appear to have been surveyed under General Roy, and 
 chiefly on the north-western coast, and in the private surveys of 
 Lord Macdonald’s estate, including North Uist, with a portion 
 of Sky. In most other districts, the errors, omissions and 
 falsities are nearly incredible, so that the country can scarcely 
 be recognized ; while, unfortunately, this Map has proved worst 
 where the wants of the geological surveyor, arising from the 
 intricacy of the rocks, especially demanded accuracy of detail. 
 And perhaps this is most true of Aberdeenshire, which being in 
 every respect one of the most difficult portions of Scotland to 
 examine and record, seems also to have the worst map in the 
 whole of this compilation. 
 
 I need not repeat that the circumstances of the physical 
 geography form joint references with those of the political, for 
 the placing of the rocks on the geological draught. But in the 
 uninhabited tracts there are none but the former, since these are 
 without houses or roads ; so that when false or deficient, there is 
 neither guide nor resource, while no system of measurement short 
 of a new geographical survey would serve any purpose. An in- 
 spection of the Map will show the great extent of country pos- 
 sessing this character, and the corresponding amount therefore of 
 difficulty or impossibility in attempting to give a true geological 
 survey. 
 
 It is scarcely necessary to repeat, that the circumstances in 
 physical geography here alluded to, consist in the outlines of sea- 
 coasts, in the courses of rivers, in lakes, and in the forms and 
 distribution of hills, together with the relative altitudes of land. 
 With some exceptions, which are chiefly on the eastern coasts, 
 though not thus limited, and in the misplacement of Barra and 
 Rona, there has been little reason to complain of the maritime 
 outlines, though there are abundant geographical errors in them. 
 The same for the most part is true of the rivers, as far as my 
 work has been concerned with them. But a large and most im- 
 portant lake, together with a smaller neighbouring one, is omitted 
 in Sky, sufficiently marking the negligence of this Map. I allude, 
 in the first, to Coruisk. And from its antiquity, it happens that 
 many spots represented as lakes are now solid land, whether 
 from alluvium or drainage ; as in Aberdeenshire, in Kinross (or 
 Fife), and at the upper part of Loch Awe. 
 
 But these are of small moment to the geological survey, com- 
 pared to the deficiencies in the drawing of the ground ; while 
 even the total omission of all the interior physical geography, as 
 in Rasay, Lewis, Benbecula, and more places, however discredit- 
 
14 Memoirs to FL M. Treasury respecting the 
 
 able, has fortunately produced no evil effect as to this Survey, 
 from the casual coincidence of them with simplicity in the 
 rocks. It is far otherwise as to the distribution and altitudes of 
 
 the hills. , , . p .... 
 
 Were Scotland represented by the drawings or a military sur- 
 veyor, or in the manner of the best recent maps, there would 
 scarcely be a difficulty to the geological surveyor, either m the 
 examination or the record, above all, in the hilly and moun- 
 tainous tracts ; and an accurate map would be as easy to make 
 as it would be sure of avoiding all criticism. Such a draught of 
 ground is a guide to the rocks, because its forins depend on 
 them ; and on such a draught also they can be laid down with 
 precision. It is not too much to say, that every thing the reverse 
 
 15 true of the present Map ; and thus does each class of difficulty 
 multiply, as it also becomes impossible to define the several 
 rocks j ustly. There is no guide at all in the drawing, or else 
 it isa false one; and thus again follows the eternal mortification 
 of finding that all the labour of investigation has been thrown 
 away, for want of the means of recording it. 
 
 It would require but a small geologist indeed to lay down the 
 rocks of any part of England on the Ordnance maps ; as he is to 
 be envied on whom such a duty may hereafter fall : while the 
 reputation which the public will probably assign to him, ought 
 in justice to be transferred to the geographical surveyors of that 
 splendid work. 
 
 It would form too long a criticism to point out in this Map the 
 defects and errors of this nature. Essentially, the deficiency is 
 universal, because the mode adopted to represent the ground is 
 a bad one, even where the basis is not untrue. In the details, 
 the leading errors are, untrue positions, untrue forms as referred 
 to the ground plan, untrue elevations and untrue proportions in 
 those, an entire want of distinctive characters, and lastly, the 
 omissions of existing hills, with the exaggeration of many that 
 have but an indistinct existence, and the fabrication of others 
 which are absolutely non-existent. It is easy to see how much 
 this class of error must add to the apparent geological mis-state- 
 ments arising from all else already noticed ; as also how it must 
 often be a peculiar source of error or uncertainty in the geological 
 draught, in those great tracts where there is no other guide and 
 basis but the forms and distributions of the mountains. As before, 
 I shall select a few examples in proof of this criticism ; while any 
 one who shall examine the country may easily multiply them : 
 noticing only, as an act of justice, that with few exceptions, that 
 portion of Sutherland and Ross which I presume to have been 
 derived from General Roy’s surveys, is executed in a very cre- 
 ditable manner, and is often remarkably true. 
 
 Meal Fourvony, which is scarcely distinguishable from the 
 general ridge to which it belongs, is represented with as much 
 force as Ben Nevis : but if that is of little moment to the mere 
 geological survey, it is far otherwise with Ben Nevis itself, of 
 
16 
 
 Geological Map of Scotland, 
 
 which the draught is so very incorrect and fanciful, that it is 
 impossible to lay down on the Map the alternations of gneiss 
 and mica slate which occur along the train of mountain summits 
 lying between it and Loch Treig. But far worse is that tract 
 of mountain land which extends from Cruachan to the moor of 
 Rannoch ; where, for a wide open valley in nature, there is sub- 
 stituted in the Map a wall of lofty mountains. And as the joint 
 boundary of the gneiss and granite lies here, it became quite im- 
 possible to conjecture where it ought to be placed in the Map : 
 whence the record which I have been compelled to make is that 
 of mere hazard. Of this large tract I may indeed say generally, 
 that the badness of the Map rendered it impossible to lay the 
 rocks down truly, so that, like much more, a true statement, 
 under such corrections as a new geological survey may render 
 necessary, must be deferred till a new geographical one has been 
 made. 
 
 I might make the same or similar remarks on a hundred other 
 places, were it not impossible, in a memoir like this, to multiply 
 such details. The same kind of errors exist all over the Map ; 
 and they are often the worst that could have existed, because, 
 as I have already remarked, the rocks and their changes are the 
 causes of the hills and of the variations of their ibrms. Thus a 
 false hill implies the entry of a rock in a false manner, as a mis- 
 placed one leads, either to the equal misplacement of a rock, or, 
 if other neighbouring rocks will not permit of this, to the placing 
 it on perhaps a flat, when its place is the summit of a hill. A re- 
 markable case of this kind occurs in Banffshire. And if these 
 very provoking sources of unavoidable, yet]of known and conscious 
 error, in the geological entries, be added to all the rest, it will 
 be easy to conjecture what must be the extent of incorrectness 
 in this work ; yet of incorrectness which could not have been 
 avoided, and for which the surveyor is in no manner responsible, 
 as he has here desired that it shall be fully appreciated. Through- 
 out, it is not a true representation of nature, as the geology is 
 concerned, but an attempt to adapt such a representation to a 
 fundamentally false geographical basis. How much additional 
 labour, added to doubt and hesitation, has arisen from this cause, 
 I need scarcely urge ; but I can safely say, that on a competent 
 map, the work would not only have been truly done, but done 
 in far less time ; as, if it had originally been commenced under 
 a regular plan, with an intention of executing it throughout from 
 the commencement, it might easily have been finished in per- 
 haps half the time which it has occupied, and with a far different 
 accuracy. 
 
 But when I thus speak of its inaccuracy, it is from assuming 
 that a geological survey should be truly geographical; from 
 taking a standard which I know will never be reached ; since 
 there are many other impediments to perfection than those of a 
 bad geographical basis, as I shall hereafter point out. Yet this 
 
IG Memoirs to II. M. Treasury respecting the 
 
 perfection ought to be the aim of every one ; as it has been my 
 own in all those portions which were examined after the mten- 
 tioi/to produce an entire Map had arisen, and the work had been 
 commanded ; as far as the limited time allowed of this accuracy 
 of investigation. Hitherto, geological M aps have been of a very 
 difiereiit character : being broad general sketches, of whi^ the 
 greater parts were conjectural, without any great regard to boun- 
 daries, and with a suppression of those geographical details by 
 which they might be verified ; while, instead of being the pro- 
 duce of actual surveys, they have been largely compiled trom 
 verbal and manuscript reports, and from the discordant views or 
 different persons, often very incompetent to such a work. He 
 who merely sees such a map will think it a great, and perhaps a 
 perfect effort ; since it is tried by its own statements : but he 
 who may labour to verify it on the ground will form a truer 
 judgment, and, if a severe critic, or an unpardonmg lover ot 
 truth, may view it with contempt, or reject it as fiction or pre- 
 tence. That even such a sketch may have some uses m geolo- 
 gical science, may however be admitted ; but it can never form a 
 statistical survey, whatever aid it may furnish to future obse^ers. 
 The present effort, and the first of its kind, while it is all the 
 work of one hand, under at least a consistency of views, will, 
 with all its defects, form the basis of a new ara m geological 
 surveying ; and I can only regret that it was impossible to execute 
 
 all that 1 wished. . 
 
 After such a statement of difficulties and imperfections, aris- 
 ing from the imperfections of the geographical basis, it is easy to 
 remark that such a work should not have been attempted, and 
 not less easy to represent it as useless for its professed objects. 
 But the imperfections of the Map were not suspected by any one 
 when it was commenced ; they only developed themselves during 
 the progress of the work, when it could not have been aban- 
 doned. Nor was it right to abandon, or delay, even so deficient 
 a work, when there was no immediate prospect of a better geo- 
 graphical survey ; since it was to prolong to an unknown period 
 the pursuit of a useful study, because a collateral one was not 
 
 yet perfected. . . , ■ t i 
 
 Nor is its utility marred by the imperfections which 1 have 
 noticed. The general distributions and places of the rocks which 
 form Scotland will now be known ; whereas, before this, with 
 exception of my own work on the estern Islands, and Hr. Hib— 
 bert’s Map of Shetland, (a survey of great merit), not a mile of 
 land in all Scotland had been surveyed and recorded. The 
 whole country, indeed, islands and all, were so absolutely un- 
 known when I commenced this vvork, that I was unable to bor- 
 row the description of a single mile in aid of it ; as, throughout 
 its whole progress, I have not derived even a hint, far less a fact, 
 or an acre, from any other hand. • 
 
 But while, with its acknowledged imperfections, it will now 
 
17 
 
 Geological Map of Scotland. 
 
 form the basis of a more accurate work at some future time, I 
 must here notice what the facilities and the diflSculties of such 
 a work will be. 
 
 Every geologist has found it abundantly easy to follow in the 
 track of him who has gone before, though utterly incapable of 
 performing an atom of the original survey. All the difficulty of 
 discernment and investigation is overcome ; all the greater tracts, 
 requiring all the labour and all the knowledge, are laid down ; 
 and nothing remains for the follower, but to settle boundaries 
 with more accuracy than the divided and extended attention of 
 the original surveyor permitted. He may spend months on a 
 few points, where his precursor had not hours to bestow ; and 
 with nothing more to do than to correct the mere geography, 
 since all else is done to his hand. And thus also he may dis- 
 cover small tracts of rock which his teacher had passed by, or not 
 approached, over the great surface under his care. Hence he 
 becomes the corrector ; as a multiplicity of such correctors, and 
 nothing less than numbers and time, will at length produce a 
 perfect work. If thus also he becomes the petty and censorious 
 critic of what he could never have understood till it was taught 
 him by the precursor whom he criticises, he must seek his praise 
 from minds of a similar calibre and feeling; since he will assuredly 
 be placed in his due station by the learned, the judicious, and 
 the honourable, though men of this nature must be sought in 
 posterity. 
 
 He who desires, from views of utility, not from vanity and the 
 love of censure, to extend the present work to a larger scale, and 
 to a greater multiplicity and accuracy of detail, will now have 
 the means of doing this. It is true that he cannot do it without 
 a fresh survey of the ground ; but while his limits are likely to 
 be that of a county, or less, his toil will not be great. The 
 places and the natures of the rocks are before him, together with 
 their general extent and limits, and often their accurate bounda- 
 ries. His first labour will consist in the adaptation of an imper- 
 fect to a better geography, and of a small scale to a large one. 
 This done, a re-examination of the stated boundaries, with such 
 corrections as they may require, either from their own defects, 
 or that they may be applied to a larger and better map, will 
 complete his work ; and he may thus construct county maps of 
 geology, if such be his wish, with an accuracy as great as can be 
 desired or expected. Nor will it require a refined geologist to 
 do this. The rocks are few, and it is easy to learn to recognize 
 them ; there is nothing which any man may not attain, on this 
 narrow subject, with a few weeks of experience. It will confer 
 no particular fame on any future self-constituted geologist, to 
 have done what could have been effected by a surveyor's drudge 
 or a Scottish quarryman. 
 
 It will be a task of far other labour, to reproduce a new geolo- 
 gical Map of Scotland, whenever a true geographical survey has 
 been executed and published. Yet it will be but an extension 
 
 c 
 
18 Memoirs to 11. M. Treasury respecting the 
 
 of the same species of labour. It will not be necessary to re- 
 examine more than a very small portion of the whole of Scotland , 
 since the chief work, as before, will consist in the corrections of 
 places and boundaries, deficient or faulty on the present Map, 
 from some of the causes already stated, and from others which 
 will shortly be noticed. It may prove, for aught I know, that 
 the coincidences between a true survey and the present Map are 
 greater than I have imagined ; and in this case the labour will 
 be still lighter than I have supposed. But, whatever may be the 
 result, it is plain that such a new w^ork will supersede the pre- 
 sent one, as it ought ; although the time for the execution of 
 a perfect geographical survey of the whole of Scotland seems 
 now so distant, that our posterity alone can expect that perfect 
 survey which I would willingly have accomplished, had it been 
 possible. 
 
 On both these classes of correction, or attempts at better 
 geological maps, I must make this final remark, that they will 
 be better executed by him of an accurate geographical eye and 
 tact, than by a better geologist who is deficient in this most 
 essential quality. It is not nearly so difficult to know the nature 
 of the rocks as to recognize the ground, together with the ob- 
 server’s place, and thence to refer the former truly to the map ; 
 and hence it is that I should expect a future and more perfect 
 geological map from the hands of a geographical surveyor rather 
 than from those of a geologist ; above all, from a practised mili- 
 tary surveyor and draughtsman. In reality, it is to the military 
 engineers who may hereafter survey Scotland, that I should look 
 for the final perfection of this work, as I trust that it may be 
 deputed to those persons, whenever the time shall arrive. 
 
 I must now proceed to notice some other circumstances con- 
 nected with this Survey, which render it a far less perfect work 
 than I should have desired to produce, or to sanction by my 
 name ; far more, to produce as a regular survey, ordered from the 
 beginning by His Majesty’s Government, and executed under 
 their authority. It would be necessary to do this, merely on 
 account of the public, in case of publication, lest blame should 
 be attached where no blame is attachable ; whether to myself, 
 or to the Government which employed me to finish a work 
 begun without any specific order, or sanction, or appointment on 
 their part. This appears the more necessary, because I do not 
 think that my Lords Commissioners of the Treasury are fully 
 aware of the particulars and progress of this work, in as far as 
 those parts of it executed under the Board of Ordnance are con- 
 cerned, although the general facts were explained at the time that 
 they decided to order its continuance and accomplishment. 
 
 The first journeys which I undertook in Scotland were for a 
 partial purpose required by the Ordnance, of a very limited prac- 
 tical nature. But as it thus became necessary to traverse many 
 tracts of country, though somewhat widely dispersed, I felt that 
 
Geological Map of Scotland. 1 9 
 
 I might, without any diversion of time, or any additional expense 
 to the Government, note the other geological facts which fell in 
 my way, and thus produce some sort of partial surveys of the 
 country in general. Many portions of the ground, of some ex- 
 tent and continuity, became thus known, with considerable 
 accuracy ; while, in other districts, dispersed and partial tracts 
 were recorded in a similar manner; yet with no other views 
 than as an aid or a contribution to that philosophical geology 
 which was then becoming an object of new interest in England 
 and Scotland. Of course, no report of such supernumerary 
 work was made to the Board of Ordnance, as no expense to 
 the Government was incurred; whatever proved to be irrele- 
 vant to the matters ordered, having been defrayed by myself; 
 as appeared just. 
 
 The time occupied in this work having included parts of three 
 summers, the final record of the whole showed that a somewhat 
 notable portion of Scotland had thus been laid down, though in 
 a very dispersed and unconnected manner ; while, though it fur- 
 nished facts of much geological interest, it gave no prospects of 
 any survey of a nature jointly mineralogical and statistical, even 
 for the tracts thus examined. Thus it remained for a time ; 
 unthought of, and without any further design or views. 
 
 But, immediately after this, it having been suggested by the 
 mathematicians interested in this question, that the estimate of 
 the weight of the earth derived from the observations of Dr. 
 Maskelyne on Schihallien and the subsequent computations of 
 Dr. Hutton, was inaccurate, and that the source of this inaccu- 
 racy lay in imperfect geological knowledge, first, and essentially 
 in the choice of a bad subject for the fundamental experiments, 
 the discussions respecting the propriety of repeating these obser- 
 vations on a more favourable subject and mountain were revived. 
 Mr. Playfair had offered a correction, derived from a new geolo- 
 gical examination of Schihallien, which gave its specific gravity, 
 as the fundamental element of the whole calculation, very differ- 
 ent from that which had been assumed. In the mean time it 
 fell in my way to review this examination ; in which I pointed 
 out numerous and serious errors, arising from a false view of the 
 extent and positions of strata of highly different specific gravi- 
 ties, and from a very mistaken and uninformed mode of esti- 
 mating those as they must have borne on the total effect of this 
 mountain in causing the deflections of the plummets from the 
 perpendicular. Thus it came to light, that if, in the first place, 
 the weight of the earth was not justly assigned from Dr. Maske- 
 lyne’s experiments, so, in the next, the corrections of Mr. Play- 
 fair were not corrections of the error; while the other and final 
 conclusion was, that however Schihallien might afford a conve- 
 nient object of mechanical measurement, and however perfect a 
 subject it might therefore have been could its specific gravity 
 have been truly ascertained, with the several actions of its com- 
 plicated structure on the plummets, and thus on the directions 
 
20 Memoirs to TL M. Treasury respecting the 
 
 of the observing instruments for the stars, the great intricacy of 
 its geological structure, and the consequent impossibility ot 
 justly assigning its influence as well as its absolute weight, ren- 
 dered it a hopeless subject for this fundamental investigation. 
 
 It was in consequence of these discussions that I was ordered 
 to make a general examination of the mountains of Scotland, for 
 the purpose of discovering some one among them, on which 
 these experiments might be repeated with the prospect of a more 
 accurate result. This work occupied many seasons ; as it also 
 led me widely, though dispersedly, over the larger part of that 
 country, since the far greater number of the expected subjects 
 proved unfit for the purposes in view, from various causes; 
 while the whole of this investigation is detailed in a special 
 report to the Board of Ordnance. 
 
 But it thence happened, that from this compulsory movement 
 from point to point, over so much of the country, I was enabled 
 to see large portions of it ; as, in many cases also, the assignment 
 of the structure of a mountain compelled me to investigate the 
 geology of the connected and related tracts. Thus, in addition 
 to the observations made in the first division of these journeys, 
 
 I was enabled to enlarge and continue a species of general geo- 
 logical survey of Scotland, yet still in a very dispersed and irre- 
 gular manner; as 1 did not feel myself justified in expending the 
 time otherwise destined, or the public money, on that respecting 
 which I had no orders. The general intention was, to contribute 
 to geological science and to the topographical knowledge of 
 Britain, as its rocks were concerned; and thus also was this 
 particular survey terminated, with those results of which the 
 Board of Ordnance is informed in a special detailed report. 
 
 This service being thus terminated, no further prospects were 
 entertained of carrying the work of a geological survey of this 
 country any further; though all which had been done was 
 entered on the Map, in the best manner that observations so 
 scattered, and spread over so many years, without any general 
 plan or ultimate views of the present nature, permitted. 
 
 But there immediately arose another question among the ma- 
 thematicians under the Board of Ordnance, consequent on some 
 remarks of the Baron de Zach and Mr. Playfair, I presume, and 
 on the visit of the French mathematicians to this country for the 
 purpose of connecting their several meridians as used for the 
 measurement of the earth. It was proved, or suspected, that 
 the deflections of the plummet produced by the nature of the 
 ground, were or might be such as materially to influence con- 
 clusions derived from instruments regulated either by this instru- 
 ment or a spirit level ; and that from this cause the observations 
 derived from the times of pendulums might prove inaccurate, 
 with consequent false results. 
 
 A third set of journeys and examinations was therefore or- 
 dered, for the purpose of affording geological corrections, if any 
 such should prove necessary, to the observations of the mathe- 
 
21 
 
 Oeological Map of Scotland. 
 
 maticians ; while these were directed, chiefly, but not exclu- 
 sively, to the meridians that were chosen as forming the only 
 convenient coincidence in one long line, which, as being well 
 known, I need not describe. 
 
 Thus another opportunity was afforded of extending the geolo- 
 gical survey which had already been effected in the partial and 
 dispersed manner formerly stated ; and at length in such a man- 
 ner and with such an effect, that some general connection began to 
 take place, so as to give a notion of the total structure of Scot- 
 land which had never yet been formed or even conjectured. 
 The final collection of all these scattered observations on the 
 Map, which still, however, continued to be nothing more than 
 an object of philosophical curiosity, or the source of a hope for 
 improving geological science, served at length to show the pro- 
 gress that had been made in a general survey of Scotland ; while 
 that was found to be much greater than had been supposed be- 
 fore this approximation of all these different surveys on a single 
 draught. 
 
 It is now necessary to say that, thus far, no public expense 
 had been bestowed on this geological and general Survey. The 
 Board of Ordnance had not commanded these additional obser- 
 vations, nor designed such a survey. They were occasionally in- 
 formed that this supererogatory work had been done, as the pro- 
 gress was regularly stated after it had assumed a tangible shape.. 
 They did not object, as they did not order; nor was there any 
 apparent reason for objecting, as none of the time due to the 
 commanded service was diverted to this purpose, and as every 
 additional expense incurred by it was defrayed by myself. The 
 final result, at present, consequently is, that out of the whole of 
 this Survey as now completed, but a very inferior moiety has been 
 paid for by the public money ; since a special and distinct sur- 
 vey, under each of the heads already stated, was completed and 
 reported, under the orders that were issued and the payments 
 that were assigned by the established regulations of office. The 
 whole, therefore, of this supererogatory survey, forming the basis 
 and principal portion of the total work, must be considered as 
 having been furnished, or contributed by the surveyor, free of 
 all pulDlic expense ; and thence the public money expended on 
 the latter portion must be distributed as if over the whole, since 
 it is the sole one that has been incurred for the total Survey. 
 
 It remains to say, on this subject, that when the work had 
 arrived at the condition already stated, so as to afford a rational 
 hope of a complete survey of Scotland, it was proposed to the 
 Board of Ordnance to continue their former orders, for this spe- 
 cific end. This, however, was not deemed expedient on their 
 part ; but the question having been referred to the Lords of the 
 Treasury, the further prosecution was adopted by them, with the 
 result of bringing it to the present termination, in the exact time 
 which had been originally estimated as necessary to its com- 
 pletion. 
 
 c 3 
 
22 MeTHoifs to IJ- M> TreasuTy respecting the 
 
 If this statement be requisite for other reasons, so is it niost 
 essential for the purpose of accounting fer another source of de- 
 fects or errors, different from that already detailed as arising 
 from the imperfections of the geographical basis on which this 
 Survey is delineated. If such a work had been originally in- 
 tended and ordered, a plan would have been laid down, as it 
 would have been consistently pursued ; as thus also the atten- 
 tion would not have been diverted from the mam object by the 
 petty details of different partial and limited subjects. In the 
 present case, where there was a specific order for an ol^ect 
 equally special, every thing was slurred over or omitted which 
 miffht in any way have interfered with that. Thus it necessarily 
 follows, that if there are not any absolute omissions, there are 
 many imperfections, and unquestionably many errors, m all that 
 portion of this Survey which was executed before it came under 
 an order of the Treasuiy for this specific end. The time applied 
 to it was inadequate, as the necessary attention could not have 
 been with justice given to it, where there was no order to ^at 
 effect, and where another set of orders were to be executed. 1 he 
 dispersion of the observations, the very distant times at which 
 they were made, the total absence of any possible plan or con- 
 nected series of observations, with the necessity of joining these 
 in the best practicable manner at after periods, and the absence 
 of any intention to produce an accurate statistical work, while 
 the only hope was to give some aid to geological philosophy and 
 kiiowledo-e through new topographical facts, will also account 
 and apologize for inaccuracies for which no other apology ought 
 to be required beyond this simple statement. It is one which 
 equally relieves from all blame, the surveyor whose work it is, 
 and the Government under whose orders it seems to have been 
 entirely executed. Neither can be justly deemed responsible for 
 the entire accuracy of a work which neither intended or expected 
 to bring to such a conclusion ; while it is especially due to the 
 Government to say, that in ordering the conclusion of a work 
 thus unexpectedly commenced, they not only took a liberal view 
 of its utility, but adopted the best expedient also for producing, 
 in as short a time as possible, and at the least expense, a work 
 which, as far as it could be of any use, ought to have been pro- 
 duced as soon as was practicable, though it had been but as a 
 basis for a future and better work of the same nature. 
 
 Unquestionably, it would have been very desirable to have 
 reviewed and corrected all those parts of this survey, which were 
 executed under the Ordnance in the irregular and almost pur- 
 poseless manner already stated ; but it was not deemed advisable 
 to do this, under views of either expense or time ; and justly, 
 since the gain could not have atoned tor either of these saciifices. 
 I must therefore finally remark, as the main result of this histo- 
 rical statement of the origin and progress of the present Survey, 
 and as that for which it has thus been made, that in addition to 
 the geographical causes of imperfection formerly detailed, the 
 
23 
 
 Geological Map of Scotland. 
 
 source of some of its greatest defects must be sought in the un- 
 avoidable circumstances under which it was carried on. I have 
 no doubt, therefore, that the imperfections in the earlier parts of 
 this work are considerable : while they are also dispersed over 
 every part of the country, in such a manner that nothing but an 
 entirely new survey, now inadmissible, or imprudent, until a new 
 geographical survey has been executed, could rectify them. But 
 if the very circumstances of these early surveys prevent me from 
 pointing out where they are likely to exist, it is my duty and 
 business to request, that whatever defects, not dependent on a 
 false geography, may hereafter be discovered, they may be attri- 
 buted to this cause : that all parties may equally be exempted 
 from blame, for what could not have been otherwise. 
 
 This must suffice on the two great and leading sources of im- 
 perfection in the present Mapt it remains to notice a few more, 
 of a far minor influence, that nothing may remain untold, from 
 the knowledge of which future corrections may be derived. 
 
 In a country previously unknown to geology, as Scotland was, 
 no plan for intersecting it, so as to ascertain all its rocks in the 
 best manner, could be formed ; nor could such a plan have been 
 executed though it had been laid down, since the time allotted 
 to this subject, under arrangements and orders that could not be 
 counteracted, was insufficient for such a purpose. Hence it is 
 a matter of course, that over a surface of nearly 30,000 square 
 miles, and in a country which is frequently of the most difficult 
 access, as it is also widely obscured by bogs and alluvia in addi- 
 tion to soil and cultivation, many portions must have escaped 
 observation altogether ; as others, though visited, were rendered 
 unintelligible, by the effect of thick rain, so frequent in Scotland 
 and so well known, making every thing invisible ; while it was 
 not often that the allotted time permitted these parts to be re- 
 examined. , . 
 
 If the effect of these several causes in producing imperfections 
 or oversights has not been great as far as the larger tracts of 
 rock are concerned, it is probably otherwise as to the smaller 
 spots, although nothing but future examinations will discover 
 whether it is so or not. I deem it exceedingly probable that 
 there are many such omissions, as I happen also to know, through 
 information which I can trust, that there are some ; although in 
 almost every case where I have attempted to verify such infor- 
 mation by re-examination of the ground, I have found it so in- 
 correct in some manner, or so entirely false, that I have been 
 obliged to decline the insertion of those additions or corrections 
 which have been offered by persons in whose knowledge or accu- 
 racy I could place no confidence. It is enough to be responsible 
 for our own errors. 
 
 Now the smaller tracts of rock to which I allude are confined 
 chiefly to granite, porphyry, primary limestone, serpentine, and 
 mountain limestone ; though in the vicinity of the trap rocks 
 
 C 4 
 
24 Memoirs to H. M. Treasury respecting the 
 
 ^here are freauently minute portions of the several strata existing, 
 and often so very small that the Map has no room to express 
 them ; while similarly minute parts occasionally occur m almost 
 all the rocks, and perhaps most importantly in that scattered 
 and divided and encumbered tract of has, with its associ^ed 
 strata, which is found on the western shores of Scotland. The 
 general facts respecting these I must now note, while 1 must 
 also name the most conspicuous cases of known or conjectured 
 deficiencies; the former as a needful correction to this Map, 
 and the latter as a guide to those who may hereafter labour to 
 
 ThouD^h granite often occurs in considerable tracts, it is also 
 found in extremely small portions, surrounded by entire terri- 
 tories of gneiss, and moreover intermixed with it in such a man- 
 ner, that unless such spot were examined yard by yard, the two 
 could not be defined ; while even if thus ascertained, neither this 
 Map, nor one ten times as large, could find room for the record. 
 
 I may also add that such minute accuracy would form an unwor- 
 thy pursuit, being of equal inutility to statistics and to scientific 
 geoloo-y ; as it would be a blameworthy one, were more important 
 things neglected for so paltry and affected a purpose. In any 
 view, this, like much more, is the proper object of partial geolo- 
 gical investigations and draughts; where, both the time em- 
 ployed, and the space of the drawing, admit of this minuteness ; 
 and it will thus become the future work of others. 
 
 Such spots of granite, it ought to be well known, are extremely 
 difficult to find, as it is chance also that must most often lead to 
 their discovery. They have no external conspicuity or characters 
 by which they may be recognized at a distance, so that unless 
 the hand is actually on them they may escape notice. And 
 though most geologists would search the summits of mountains 
 for them, my experience shows that this is no guide or mle. At 
 Loch Spey, Loch Laggan, and the Moor of Rannoch, the lowest 
 lands are of granite, often perfectly flat as well as low, so as to 
 give to the ground the same character as the horizontal secondary 
 strata do, while the surrounding mountains are formed of dif- 
 ferent stratified rocks. And this also is very widely true in 
 Aberdeenshire, adding enormously to the other difficulties which 
 belong to that county. It is plainly impossible, as it would be 
 a censurable waste of time, to search such a country as the west 
 of Ross and Inverness-shires, inch by inch, for every such spot 
 of granite as it may contain ; while even a search of this nature 
 would be unavailing, when such large surfaces are covered by 
 deep bogs and accumulations which render the rocks invisible 
 and inaccessible. In the stratified rocks, it is easy to infer what 
 cannot be seen ; while it is thus indeed that geology performs 
 the principal part of its work ; but, of granite, nothing can be 
 known except through an actual sight of the rock, and this is too 
 often unattainable. 
 
 Of examples of the occasional minuteness of the spaces occu- 
 
26 
 
 Geological Map of Scotland. 
 
 pied by granite, I may now point out two or three on the present 
 iVJ ap. They were entered as examples of this fact ; while many 
 others have been omitted, under the conviction that they would 
 not be discovered on the Map, amid the general confusion of 
 engraving and colouring, and the certainty that the colourmen 
 who might be employed in making copies would overlook the 
 greater number. Even in those which are recorded, I have been 
 obliged to enlarge the spaces a hundred or a thousand times, 
 since they would have been incapable of representation under 
 their actual dimensions; so that, if critically considered, the 
 entries are false. 
 
 Such a minute fragment will be seen between Loch Tumel and 
 Loch Rannoch, and its actual breadth is but a few yards. There 
 is such another represented on the Buck of Cabrach, in Aber- 
 deenshire, again near New Galloway, and further, near to Kirk- 
 mabreck, and at Heston island ; though the space being here 
 forcibly limited by the size of that island on the Map, the facts 
 cannot be decyphered unless a section on a larger draught had 
 been also given. 
 
 If these, like many other things in this Map, are partly given 
 as proofs of an accuracy and minuteness of investigation which 
 has almost turned out purposeless, from the impossibility of re- 
 cording it for want of room, so have I in one place given a repre- 
 sentation of the actual facts which occur at the j unction of granite 
 with the neighbouring strata. This will be seen on the summit 
 of a hill near Castletown of Braemar ; yet even the intermixture 
 of colours, intricate as it is, does not represent these facts, since 
 twenty times the space would not contain them. Whatever 
 number of such intricate j unctions were ascertained, it was plainly 
 impossible to represent them on this Map, especially under the 
 heaviness of the engraving ; while even an attempt to do this 
 would have produced inextricable confusion, as it would have 
 rendered it impossible for the colourmen to copy them, without 
 an enormous and unjustifiable expense. Hence it has been ne- 
 cessary in this case, as in a thousand others, to give such boun- 
 daries in their most simple forms ; while this specimen will show 
 what might have been entered, as it was surveyed, had such 
 entries been practicable. 
 
 It was equally impracticable to represent the minute intermix- 
 tures of granite and gneiss which occur in many places, appearing 
 to arise from the fact that the latter has been bared nearly to 
 the surface of the former. And while it also seemed unnecessary 
 to note this fact wherever it occurred, I have for the same reasons 
 given one example of it, partly as a specimen of the fact, and 
 partly because of the conspicuity of that particular tract. But 
 the hieroglyphic colour used to express it is so very aukward, 
 while I could not find a better one that should be sufficiently 
 visible in small spaces, that I have not repeated it in any other 
 place. This is a tract round Loch Garry ; and the ring of Sienna 
 surrounding gamboge is the expression adopted. 
 
2(3 Memoirs to II. M. Treasury respecting the 
 
 Similar remarks will apply to the granite veins. Had they 
 been given, they would have obscured the work by fibres ot 
 brown colour, and would also have been invisible, without that 
 enlaro-ement of length and dimensions which vyould have egre- 
 giousty falsified their sizes and places. In this case therefore, 
 also, I have confined myself to an example or two, as \yill be 
 seen near Banff; and if useful in this particular instance, this wiff 
 also serve to show what might have been done elsewhere, had 
 the circumstances permitted. 
 
 The masses of porphyry, though equally an independent rock, 
 have offered less difficulty, especially where they occur in the 
 northern parts of the country. In the south, the case is uitierent, 
 thouP'h they are here represented under the hieroglyphic of trap, 
 for reasons which will be explained in another place. 1 hough 
 there are here many large masses, respecting which there is no 
 difiiculty, there are also numerous fragments, as well as veins, 
 scattered over the surfaces of the slate hills, in the vicinity of 
 Hawick, Langholm, and elsewhere. The same reasoning applies 
 to these as to the small patches of granite already noticed. I he 
 depth of soil and peat entirely obscures many of them, and they 
 have no external form to distinguish them from the neighbouring 
 slate. The search for them is therefore attended by the same 
 difficulties, while the small importance of such fragments, under 
 any view, did not justify the expenditure of time on them, where 
 there was so much more of far greater importance to be done, 
 and when the time for the whole work was positively limited by 
 the Government’s plan respecting this Survey. 
 
 The absolute nature of that Order compels me now to make 
 the following general remark, as universally applicable, and as 
 leading to many more similar imperfections ; or as at least ren- 
 dering it probable that there are such. It could not be^ foreseen, 
 at any stage of the work, what there might be remaining to be 
 done, and what time therefore it might occupy. Hence it was 
 necessary not to waste that which was so circumscribed, on a 
 peculiarly difficult tract, especially when it did not prove of much 
 importance, lest it should fall short on the remainder, and thus 
 le^e more important tracts untouched and blank. And this 
 compulsory haste, under a limitation of time for the execution of 
 that which was unknown and could nowhere be foreseen, when 
 the due performance of such a work demanded an entire freedom 
 from all restraint, will very widely explain imperfecjtions, or 
 sketchiness of execution, that will in all probability be discovered 
 by future observers in many places; as I could now point out 
 those where I expect they will be found, were it not too tedious 
 an enumeration, and, if made in words, much too difficult to 
 verify on the Map ; since it would become an almost impracti- 
 cable search for names to which a guide could hardly be invented. 
 
 To the veins of porphyry I may apply the same remarks as to 
 those of granite. In many places they are so small that they 
 could not be represented on the Map, as no useful purpose also 
 
27 
 
 Geological Map of Scotland. 
 
 could have been served. But I have given a few examples of 
 such veins where they were most I’emarkable, yet, of course, 
 under a dimension on the Map infinitely greater than they pos- 
 sess in nature, since they would otherwise have been invisible. 
 Even now it is difficult to see them, as they are also very likely 
 to be missed by the colourists. In Glenco, where they are most 
 remarkable, they are laid down under a general expression, since 
 their crowd and numbers did not admit of an accurate record. 
 
 I would gladly have marked them also as they passed through 
 Cruachan and the Oban trap ; but I found it impossible to give 
 more than a general indication of the fact by means of a few red 
 lines, the purple colour appropriated to this rock not being 
 sufficiently visible on the engraved ground and the other colour- 
 ing. I especially desire attention to this, lest they be wilfully 
 or carelessly mistaken for the mountain line, expressed by the 
 same colour. 
 
 The difficulty of discovering and representing the primary 
 limestones has been a much more vexatious one, because of the 
 practical uses of this substance, and the frequent inconvenience 
 to agriculture and masonry, arising from its rarity in the primary 
 districts of Scotland. 
 
 In every instance this rock exposes only the edge of the strata 
 or stratum, while it is, in almost every instance also, but a single 
 and a very thin bed; so that its superficial breadth seldom 
 exceeds a rew yards, and often does not reach to many feet. In 
 addition to this, either these beds are very limited in length, or 
 else they are extenuated till they disappear, to be apparently 
 renewed in a fresh place on the same line of direction. And if 
 to this be added the fact, that so many tracts are covered for 
 miles by deep masses of peat, it is plain that not even an inves- 
 tigation of the ground by inches could find them all, while such 
 a work alone would occupy more than the life of one man. It is 
 utterly impossible, therefore, that I should have discovered, per- 
 haps, the least portion of them, since they must generally be 
 discoveries of pure accident. Yet I have examined and laid 
 down all those respecting which I could procure uny information 
 from the country people ; further adding many on which 1 had 
 fallen by chance, and the prolongations of many more to un- 
 known places, eftected by tracing the directions of the stratifi- 
 cation. Of what remains, 1 cannot conjecture; except that 
 wherever I have laid one down, it will probably be found in 
 many other places on the same line, by those who may have 
 that time to pursue these partial investigations which I had 
 not. 
 
 The unavoidable incorrectness in the mapping of these lime- 
 stones will now be easily understood and allowed for. Though 
 the geography of the Map had been correct, which it very seldom 
 was found to be for such a purpose, the smallness of their dimen- 
 sions rendered a great enlargement of the heiroglyphic colour 
 necessary, though I chose, in ultramarine, the strongest and most 
 
28 
 
 Memoirs to H, M, Treasury respecting the 
 
 conspicuous one that remained to me. The least visible quantity 
 of this, being also but a line, occupies the space of half a mile or 
 more, in breadth, on the Map, that I might ensure its being seen 
 by an inspector of this record, and not overlooked by the co- 
 lourist copiers. But the actual breadth is not more than a few 
 yards perhaps ; incapable of representation, since it would not 
 have occupied half the dimensions of a hair. If in some places 
 this is of no moment, it is not so of all ; since the necessary en- 
 largement of the coloured space causes the limestone to appear 
 at some marked geographical point where assuredly it will not 
 be found ; as the observer may thus be accused of an error which 
 belongs to the very nature of things, not to him. For this tliere 
 is no remedy : all that can be said is, that such limestones will 
 be found near the places thus coloured in the Map, though not 
 over the whole surfaces, either in length or breadth, or at the 
 exact points which appear there. I need not refer to particular 
 parts of the Map for the examples, since they occur every- 
 where ; while the same enlargement of dimensions is also fol- 
 lowed in other matters, for the same reasons : but I also know 
 that many of the recorded ones are here egregiously misplaced, 
 particularly in Aberdeenshire, from the extreme incorrectness and 
 confusion in this part of the Map especially, rendering it quite 
 impossible for me to discover my own place upon it. I have 
 also retained two or three which I had taken on report, but had 
 not found ; while doubting their truth and accuracy, since, on 
 other occasions, I found myself deceived, and rescinded the 
 memorandum first made. Under such circumstances I have 
 been doubtful how to act ; and the errors therefore, if they 
 prove such, must be trusted to future coirections. 
 
 The case of serpentine is very similar, with some very trivial 
 exceptions where it is found in considerable masses. It occurs in 
 very minute spots, or very thin beds, as it is also very rare ] and 
 there is no clue by which to conjecture its presence. Thus the 
 discovery is as accidental as that of the limestones ; while in 
 each case, the accident of a shower of rain, or the mere turning 
 of the head to look at another object, may cause a surveyor to 
 miss the very thing under his feet, since he may not be more than 
 a few seconds near to it. What may have been overlooked as to 
 this rock, I cannot therefore conjecture ; but I have laid it down 
 in many places where it was before unknown, while also reject- 
 ing others which had' been reported as existing in certain spots, 
 but which I could not find after a careful examination. 
 
 In the record of such serpentine there has been the same diffi- 
 culty as in the case of the limestones. The spaces of colour have 
 been enlarged that the fact might be visible, with, of course, the 
 same appearance of error. In Aberdeenshire, where it occurs in 
 very small spots in granite, and often accompanied by limestone, 
 the records are nearly invisible, with all the care which I could 
 take. At Portsoy, where it occurs in a complicated mixture 
 with other rocks, and in a very narrow space, the accurate record 
 
29 
 
 Geological Map of Scotland. 
 
 of the whole was quite impossible. In this, as in many other 
 analogous cases, large separate drawings were made ; as it was 
 afterwards attempted, but in vain, to transfer them to the Map 
 by reduction. Such drawings could not have been published 
 with the Map ; while, being mere objects of geological curiosity, 
 not of statistical utility, they have been for the most part destroy- 
 ed, with such other drawings of special appearances as related 
 to the mere science : having no relevancy to this ordered work, 
 and there being now no means left to me of rendering them useful 
 in any other manner. 
 
 The next rock which occurs universally, or at least but with 
 one or two slight exceptions, in small quantities, is the mountain 
 limestone. In most places, the elevated edges of a thin stratum 
 are alone to be found; while in others, if flatter, it is only 
 known as wrought by excavating beneath the coal series. In 
 none, therefore, is it possible, or safe, to give it a larger breadth 
 on the surface than the visible one, though it may cover larger 
 spaces in some parts than I have been able to prove. The 
 quarrymen, it is true, are very generally ready to assert this, and 
 to say that a given tract is all limestome, because they work it at 
 different points ; but having so often ascertained that this was a 
 mistake arising from the fractures and undulations of a stratum, 
 and generally in the vicinity of trap, I have not adopted any 
 such continuous tract, except in Sutherland, where it is visible, 
 since I have not been able to prove its existence. 
 
 It is plain, therefore, that the discovery of such thin edges of 
 limestone must be, like that of the primary ones, a matter of 
 chance. There would be the same impossibility of making a 
 minute investigation for so partial a purpose ; and the difficulties 
 are even enhanced as to this limestone, by the nature of the 
 country where it occurs, and by its unexpected irregularity of 
 disposition. On the usual doctrines of geology, it ought to be 
 found every where between the red sandstone and the coal series ; 
 but it is very certain that this is not the fact in Scotland. It 
 cannot therefore be sought for through the usual guides ; while, 
 owing to the upturning of the strata, through the influence of 
 trap, it often occurs in the middle of tracts of red sandstone, 
 and of coal sandstone also, under an apparent, if not a real 
 anomaly, in each case. As this limestone also belongs for the 
 most part to the cultivated countries, where the lands are deeply 
 encumbered with alluvia, as well as obscured by cultivation, and 
 are moreover so flat as rarely to expose any rock for many miles, 
 it is plain that to discover it must be a matter of chance or of 
 extreme difficulty ; a difficulty not comprehended by English 
 geologists, where this limestone forms large and evident tracts, 
 in every place where it exists. 
 
 I may therefore say, that in no instance have I found, in the 
 south at least, any place for these limestones beyond those which 
 were known in the country, and generally as the subjects of 
 quarrying; while it is therefore plain, that their extents and 
 
30 Memoirs to H. M. Treasury respecting the 
 
 places, as laid down, must be much less than the actual facts. 
 Nothing but the total removal of the soil could discover the still 
 unknown ones, since the flatness or the irregularity of the sti ata 
 prevents their courses from being pursued or conjectured. It is 
 true that this might be safely inferred in some cases ; but there 
 are so many more where the usual rules would deceive us, that 
 it has not been deemed safe to follow them. 
 
 What the extent of the information thus received may be, as 
 compared to the actual facts, is what I cannot conjecture ; all 
 that I could do was to verify it on the ground, that I might enter 
 nothing of which I had not ascertained the existence. But in 
 attempting this, if I verified much, there was also much that 
 I could not find by any research. Whence, knowing the pro- 
 pensity of these reporters to exaggerate, and to make imaginary 
 courses for their strata, I have refused admission to such records ; 
 while it is very likely that I have thus excluded what has a real 
 existence. I suspect this to be the case in Fife, where I laboured 
 in vain to find what had been said to exist ; but I could not 
 make myself responsible for the truth of what I had not proved, 
 while I have almost invariably adhered to this rule throughout 
 the country. It is at least as easy to supply a defect as to ex- 
 punge a false statement ; and while these doubtful spots are 
 sufficiently insignificant, compared to the whole work, they are 
 among those which it will hereafter be most easy to supply and 
 correct, under partial and local surveys; under those surveys 
 which, after all, must ever be the only ones applicable to prac- 
 tical uses. 
 
 The same species of error which unavoidably occurs in mapping 
 the thin edges of the primary limestones, pervades the registry 
 of these also, and commonly to a much greater degree. Very 
 often the only accessible portion is a quarry, while there is as 
 often but little certainty respecting its extent and course beneath 
 the soil. Though one of the strongest colours is here also used, 
 in lake, the actual dimensions thus laid down would have been 
 invisible on the Map; thence is the colour extended both in 
 length and breadth, and with those similar results which I need 
 not repeat. For the most part too, although the quarries appear 
 to follow certain lines, or the edges of the strata, I have kept 
 these spots separate ; in a few cases only, connecting them by 
 a narrower line, as a general indication of what any one who 
 chooses may extend to other places by means of a hair-pencil 
 and a little colour. This, in fact, is conjectural mapping: there 
 is no objection, for those who desire no more ; but it was the 
 very plan of this work to produce a real map ; and thus, as far 
 as possible, to infer nothing, especially as to objects of practical 
 utility, which was not tolerably clear. 
 
 These are the principal facts connected with the minuteness of 
 rocks, and the consequent difficulty, both of finding and niapping 
 them, which it is necessary for him who may inspect this work 
 to bear in mmd. They form a commentary and explanation 
 
81 
 
 Geological Map of Scotland. 
 
 scarcely less necessary than the Key, that the work may be justly 
 understood; that the nature of what looks like error may be 
 appreciated, and that there may be no appearance of a pretence 
 to do what cannot and never will be done. 
 
 It remains to make some remarks on minutenesses occasionally 
 occurring, as accidents, among those rocks, wdiich for the most 
 part, form large tracts in other countries ; things with which 
 Scotland abounds, as they are rare in England, and therefore 
 scarcely suspected by those who know this latter country only. 
 If the difficulty of discovering those is occasionally as great, that 
 of mapping them is often much greater ; and therefore, at least, 
 do they demand the present explanation. 
 
 It is almost necessary to point out here the occurrence near 
 Loch Greinord, of two small spots of a sandstone which I consider 
 to be the red marl ; since they are the only ones that I have 
 found in Scotland, if I except that still doubtful portion in Arran 
 which could not be represented on the Map. They might not 
 otherwise be found, even through the Key ; since the colour of 
 that is conspicuous on the white paper, while these unavoidably 
 show the same tint in a very obscure manner. 
 
 The series of lias and oolithe, one or both, sometimes attended 
 by the green sandstone, at others containing lignite coal, is so dis- 
 persed, over so many places, often in such extremely small por- 
 tions, and very frequently under trap, so as to show no surface, 
 and to be recognizable only in the vertical cliffs, that I have not 
 been able to represent it everywhere, and seldom in any place, 
 with geographical truth ; partly from the minuteness of the Map, 
 and partly from the necessary construction of all maps. This is 
 the more disagreeable, because there is not a fragment of this 
 series, on the western coast at least, with which I am not perfectly 
 acquainted. I’hus I could not render it visible, even by the 
 violent green which I have used, in the Shiant Isles, where its 
 shale at least occurs, since these form a mere spot on the Map ; 
 nor on the summits of the Morven Hills, where only the thin 
 edge is seen, lying under trap. And thus, also, in Sky and Mull 
 and Rasay, it is greatly exaggerated, while further, often repre- 
 sented as occupying a horizontal space when it is entirely without 
 dimensions in this direction, and would be invisible on the Map 
 but for this expedient. Thus also is it sometimes indicated on 
 the sea, as the only place which would show the colour ; another 
 expedient, which I have equally been obliged to adopt for lime- 
 stones and other roeks in several places, when occurring under 
 trap. Hence also have I had recourse to a further one, which I 
 must equally note here, lest it be supposed intended to express 
 a fact, and might therefore imply an error of examination. This 
 is, to accompany it by the yellow colour allotted to the green 
 sand, which might have been there when it is not, as it is in 
 Rasay and in some parts of Mull, 8cc., and which, by its hue, 
 serves to bring out the green tint and to separate it from the blue 
 of the trap. It is plain that nothing but a far larger Map would 
 
32 Memoirs to II. M. Treasury respecting the 
 
 have admitted of a true record of things so small ; and it must 
 therefore suffice, ^to have given this explanation, when the adop- 
 tion of such a one was impossible. But in this case and some 
 others, including Sky especially, the minuteness of which m the 
 Map, with the intricacy of the numerous rocks, renders an ac- 
 curate record on the present draught impracticable, I may refer 
 to the laro-er maps which I formerly published of the Western 
 Islands. Vith equal space, almost everything in the present 
 Map might have been equally accurate ; and that which is thus 
 done in the well-known work to which I have referred, will serve 
 at least to show, that it was not want of knowledge of the facts 
 which has rendered the present one less accurate than it might 
 easily have been made, if I could have commanded more 
 
 ^Although the red sandstone generally occure in large tracts, 
 there are some extremely minute portions scattered over various 
 parts of the country. I do not believe that I have overlooked any 
 of these, though some are so minute as to occupy but a few yards, 
 insomuch that I fear they will scarcely be found without a verbal 
 direction, in addition to the colour, especially as a minute quantity 
 of lake, used for this rock, resembles the colour selected for 
 granite, when on the black engraving. 
 
 If I have sometimes, therefore, adopted the general expedient 
 of enlarging these small spots, so have I drawn out lines at their 
 boundaries, when occurring on the sea-shores ; a proceeding which 
 I have also followed with respect to some other boundaries, this 
 bein<r the only part of the Map where such lines could be made 
 visible. Yet I have been obliged to omit some, as absolutely 
 incapable of being represented ; but these, being chiefly in the 
 Western Islands, where they occur in this manner, entangled, 
 may be found by a reference to the published maps of the work 
 already mentioned. The others occur chiefly about Oban, en- 
 tangled in trap also ; while being very numerous, and seldom 
 exceeding a few feet in dimensions, there was no possible means 
 of representing them without a total sacriflce of the truth of the 
 neighbouring parts. 
 
 It is in this neighbourhood that I must point out one small 
 mass, which is here represented, though in far more than its real 
 dimensions, since it is but a few yards wide : while it has dimi- 
 nished so much, within my memory, through the inroads of the 
 river Awe, that I shall not be surprised to find it vanished in a 
 few more years, when some future examiner may deem this entry 
 of it a fiction. It is near the bridge of Awe, and the colour 
 being very dark on this shaded ground, it might easily be mis- 
 taken for some other rock. I ought also to point out a line of 
 this sandstone on the Galloway shore, equally liable to be mis- 
 taken, from the same causes, though I have exaggerated it as 
 much as was safe, that it might be visible. Similar exaggera- 
 tions, for the same reason, will be found on the shore near Mont- 
 rose, where, especially, a fragment of mountain limestone, which 
 
Geological Map of Scotland. 33 
 
 is nearly wrought out, is represented as of a large size, and ac- 
 companied in a very untrue manner by the red sandstone ; this 
 being the only expedient by which it could be marked. But with 
 respect to the atoms of this rock which occur near Cullen, Troup 
 Head, Stonehaven, Eyemouth, &c., I think that no mistake can 
 arise, in spite of the small quantity of colour, since they are con- 
 nected by red lines with the neighbouring visible masses. 
 
 With respect to the singularly placed fragments of this sand- 
 stone which occur in Sutherland, there can be no difficulty, as 
 they are sufficiently distinct on the Map. There also they are 
 accurately laid down ; but not so precisely, I fear, about Loch 
 Torridon, where the incumbrance of the ground with soil, and 
 the impossibility of finding accurate references in the geography, 
 have rendered the places and dimensions of many of these 
 intricate and troublesome parts, matters of considerable chance ; 
 although the errors, if there are any, can be of no moment either 
 to the science or the statistics of geology. 
 
 One remark more on the minuter portions of this sandstone 
 will comprise all that seems further necessary to be said on that 
 rock, as an explanation and a caution respecting the Map. 1 n 
 the south of Scotland it occurs in many places between the pri- 
 mary slate and the coal strata ; as it ought, under the common 
 principles and creed of geology. It is most certain, however, 
 that this order is not constant ; since in many places there can 
 be no doubt of the contact of the coal sandstones with the slate, 
 as I have here represented them. Now it happens that in many 
 places, and in the southern coalfield remarkably, the ground at 
 the junction of the primary and secondary strata is so encum- 
 bered with alluvia or soil as to render the rocks entirely inac- 
 cessible. Here, in some places, the red sandstone can be seen to 
 exist, in others not ; while it therefore remains doubtful how to 
 act, since the theory of their necessary consecution may no more 
 be true here than in the places thus noticed. 1 could do nothing 
 but make the best conjectures which the nature of things ad- 
 mitted ; the circumstance itself is of little moment : but by an- 
 nouncing this doubt among others, I shall have pointed out what 
 remains for correction respecting this rock also, that, in all cases 
 he who may undertake the future emendations of this Map, may 
 at least employ his criticisms to some useful purpose, and not 
 waste his time in going over what is already ascertained and 
 accurate. 
 
 Though the tracts of clay slate are generally extensive, this is 
 not universally the fact ; and there are some, therefore, which 
 demand remarks similar to those already made on the primary 
 limestones. 
 
 In the south of Scotland, in Aberdeenshire with little excep- 
 tion, and in the great belt which traverses the country in a north- 
 easterly direction, there is no difficulty in mapping this rock, 
 since there is abundant space ; while this is true also of some of 
 the islands where it exists. But there are numerous places where 
 
 D 
 
34 3 Iemoirs to H. M. Treasury respecting the 
 
 it occurs in very narrow lines ; those being the edges of elevated 
 strata, alternating most commonly with mica slate, but some- 
 
 times with gneiss also. . , 
 
 Now the same double set of difficulties occurs here as m the 
 
 case of the primary limestones, there being indeed no essential 
 differences in the distribution and appearance. The finding them 
 is often a mere matter of hazard. It is impossible, and would 
 be idle, to waste time in minutely intersecting a country in 
 search of what may not exist, and which, though it did, could 
 seldom be found, ‘from the spaces which it occupies being so 
 small, and from the incumbrances of the ground. Even when 
 these things are found, it is seldom possible to distinguish them 
 on the Map ; and not often, without a great exaggeration, and 
 with the eftects that have already been pointed out. In this case 
 also, the inevitable colouring of the Map produce^ a much greater 
 difficulty than in that of the limestones ; since the colour chosen 
 for the slate, as the only convenient one m the large masses, is 
 nearly invisible on that of the mica slate, especially it placed on 
 that (lark engraved ground which unfortunately predominates 
 
 over this Map. , , , . .1 • 4 i 
 
 If I have done the best I could to represent these minute ob- 
 
 iects, I ought also here to point out, generally, the places where 
 tliey lie, lest they should escape notice ; while they are als() veiy 
 likely to be so ill copied by the colourists as to render this ob- 
 scurity much greater. .v. • i.i 
 
 As occurring in gneiss, they are perhaps sufficiently noticeable, 
 from the contrast of colour, on the eastern sides of North Uist 
 and Benbecula, and as occupying some of the intermediate 
 small islands. I must hope that the colourists of the ccipies 
 will not overlook these atoms, which I have also included within 
 a line of the same colour, in hopes of avoiding this accident. 
 There is a similar atom near Loch Brolum in Lewis ; and while 
 on this part of the Map, let me point out a mass of serpentine 
 at Loch Valumis, and another at Scalpa, which might equally 
 be overlooked ; and further make a note respecting Loch Maddy, 
 where the two detached rocks called Maddy-more and Maddy- 
 beg are of trap, as the shore is of slate, but where the blue and 
 the green colours used are undistinguishable on the Map, from 
 the minuteness of their spaces. 
 
 This portion of the Map, including the whole outer chain of 
 islands, leads also to a remark which it is essential to make ; not 
 because it will prove the attentiveness and the labour of the in- 
 vestigations w hich have been bestowed on this work, (as any one 
 can s6e even on the Map, in the great and intricate extent of the 
 country examined, especially on these most complicated shores,) 
 but because it will remove a suspicion very naturally attached 
 to a tract represented as so uniform, and thus give confidence to 
 him who may inspect it. 
 
 It has been the usual practice in geological maps to lay down 
 w hole tracts of country from very superficial and partial examina- 
 
35 
 
 Geological Map of Scotland. 
 
 lions, and with as little attention to the minuter parts as to tlie 
 geography: thus producing maps which I have already justly 
 called sketches, or conjectural works. The sight of such an 
 extensive and intricate country as these islands form, laid down 
 as almost all of one rock, leads therefore to the very natural 
 conclusion, that the same negligent practice has been here fol- 
 lowed, and that the survey is but a conjectural representation, 
 conformable to the usual customs. But the minute circumstan- 
 ces thus noticed, show that the ground has really been investi- 
 gated, as it is also plain that nothing but a very minute and 
 accurate examination could have found them ; while he who 
 may repeat it, will discover that it is not an easy matter, amid 
 the confusion of inlets and islands, forming an absolute la- 
 byrinth, even to find out such petty islands as those that are 
 marked for slate in the Kyles Wiay of Benbecula. 
 
 The other minute edges of slate to which I alluded, occur 
 chiefly between Glen Spean, Loch Swin and Loch Awe, and in 
 the chain of Isla, J ura, &c. I can have no doubt that they are 
 prolonged much farther than they are here represented ; but as 
 in the case of the similar limestones, I could not prolong them 
 on so false a geographical basis, by following the usual line of 
 direction, without the hazard of placing them where they would 
 never be found. As it is, their places can seldom be very true, 
 from the necessity of great exaggeration, and from the badness 
 of the geography ; while additional suspicions are thrown on that 
 geography, in this case and many others, by finding that w^hen 
 this is followed, the lines of direction do not turn out to be what 
 the strata ought to bear, from a general knowledge of the coun- 
 try, nor what they appear to do wdien examined by the compass. 
 
 And I may make this remark general, since the same anoma- 
 lies occur in innumerable places. Let no one, therefore, be sur- 
 prised at seeing deviations and flexures of the lines of direction 
 on this Map : they may be real, but I am tolerably certain that 
 they are the frequent result of a false geography ; to whicli, 
 nevertheless, I was compelled to conform, since it was through 
 it the rocks would be sought, as to it they must have been 
 adapted. A future accurate geographical survey will alone show 
 what the truth and the falsity are, in this case also. But I need 
 not here point out these doubtful things ; they will be sufiiciently 
 apparent to any geologists consulting the Map. 
 
 If I may here, lastly, point out, as to the slate, the remarkable 
 manner in which it occurs in junction wdth other rocks, as near 
 Troup Head, and about the shores of the Clyde ; and if these 
 will also serve to prove the minute accuracy of the survey, so 
 do they also show, that wherever the accuracy on the Map is 
 less, it was not for want of equally accurate knowledge of the 
 facts, but because they could not be equally well recorded. In 
 these cases the Map was found as perfect as was necessary for 
 those purposes. 
 
 The quartz rock, as represented on the Map, demands some 
 
 D 2 
 
36 Memoirs to TJ. M. Treasury respecting the 
 
 similar remarks. Near Loch Leven, and in some other Peaces, 
 it occurs in very narrow lines, as in many more, , 
 
 hallien, it occupies only the narrow summits of hills, visibly 
 at leU while in many the spaces which it covers are very 
 small Thouo'h I therefore chose one of the most conspicuous 
 colours, to render it sufficiently visible, the extreme bkckness 
 of the Map has, in many places, reduced the tint so iar, that 
 I fear it will sometimes be mistaken, especially by the colourists ; 
 in which case it will become an entirely false entry to the pos- 
 sessors of copies. I can discover no means at present of avoid- 
 ing this source of error, though an extensive work of sections 
 might aid in recording the truth : it is one of the chief instances 
 in which this work will suffer from the absurd, injunous and 
 unnecessary blackness of the engraving; especially provoking, 
 .since a much lighter mode of execution, such as is used for the 
 modem maps of France and Italy, would far better have ex- 
 pressed the geography, while they would have equally removed 
 this evil. And I regret to say, that the strata of quartz rock 
 which occur among mica slate will prove especially u™cult to 
 recognize on the Map ; as I shall not be surprised to find them 
 totally unintelligible in the coloured copies that may be executed. 
 
 It is indeed most certain, universally, that this Map never will 
 be truly copied in every part, since nothing but a knowledge ot 
 the facts themselves could enable a copier to do this perfectly. 
 Even the copies made by myself have required a constant recur- 
 rence, not only to the original entries made m the field, to the 
 drauo-hts on a larger scale, and to the memorandums entered on 
 tlie spot, but to my own recollections of the places and the lucts ; 
 as, with all these means, which no one else can possess, »ud all 
 this care, I have not avoided errors in those copies, which it 
 has required numerous, repeated, and tedious examinations to 
 correct. If, to myself, and with all these advantages, the making 
 a copy of this Map has been the labour of a week, I am really 
 hopeless that any number of correct ones will be produced lor 
 sale, if this work be sold, unless a liberal price is allowed. 
 
 I'here is one other difficulty relating to quartz rock which 
 1 must here also state ; but it is one that relates rather to t le 
 difficulty of representation than of investigation ; since this, 
 although laborious, is in no other respect difficult. It is too 
 decided a rock not to be abundantly obvious, though never 
 known to exist, in any part of the world, or, as is more hkely, 
 never recognized and discriminated by my predecessors in this 
 science, till I pointed it out in Scotland, and gave it a place in 
 the system. The difficulty in question relates to its graduation, 
 sometimes into gneiss, and at others into mica slate ; as it occa- 
 sionally arises from an alternation of these rocks, but chiefly of 
 gneiss, with it, so very frequent and minute, that the approxima- 
 tion of even hairsbreadths of the different colours on the Map 
 would be an exaggeration of the truth. 
 
 It was utterly impossible to represent truly either of these 
 
Geological Map of Scotland- a? 
 
 circumstances in this work. In a set of sections I might have 
 attempted to convey an idea, though an exaggerated one, of the 
 alternations, as in others I might have indicated the graduations. 
 On the Map, the slightest endeavour after the former was vain ; 
 and if I have attempted, in a few of the most remarkable places, 
 to represent the gradations, it is really never more than a loose 
 indication of the fact, not a true geographical entry, since on 
 such a map and scale this was utterly impracticable. I should 
 have earnestly wished it otherwise, both as to these gradations 
 and those between mica slate and gneiss, so often remarkable, 
 and so especially frequent and striking about Ben Nevis, Glenco, 
 Loch Laggan, &c. ; but there are limits to every thing, and this 
 has proved one of the cases in which there was nothing left but 
 to surrender to the impossibility. It is not the only case, by 
 very many, by hundreds, or perhaps thousands, in which I 
 could not communicate the knowledge for which I had laboured * 
 and if this is a very natural source of vexation, I must also 
 desire that this knowledge may not be measured by the present 
 imperfect record. If ever maps shall be made of twenty times 
 the size and truth, future observers will possess advantages where 
 I found nothing but obstacles. 
 
 I have little left to say respecting the investigation or the 
 mapping of gneiss and mica slate, beyond that which will appear 
 in a subsequent account of those rocks among the rest. The 
 investigation is seldom difficult; and as all the difficulty of 
 representation is included under the preceding remarks on quartz 
 rock, I may pass from those substances, and next note what 
 relates to trap. Of the difficulty of investigation which attends 
 this rock in so very remarkable a degree, I must, however, speak 
 in some future remarks on this subject in general ; here noticing 
 only what belongs to the difficulty of representation. 
 
 In some places, as in Fife most remarkably, it occurs in 
 patches, among other rocks, so very small, that the Map will 
 not contain a true delineation for want of room, as I formerly 
 noticed when speaking of its bad geography and drawing. Yet 
 examples of the accuracy with which that rock was examined 
 wall be seen at a few points, in this portion of the present work ; 
 where the entries are equally true and minute, wherever the 
 space and the drawing of the Map permitted. On a better basis 
 they would have been the same everywhere. 
 
 In other places, the minute intricacy of its outline is such, 
 that it was utterly impossible even to approximate to it on so 
 small a space. The general outline which it therefore became 
 compulsory to adopt is consequently untrue, if the Map be com- 
 pared with the ground itself. As before, that which was well 
 known could not be entered, for want of means. 
 
 And if this intricacy of outline depends partly on the more 
 obvious ordinary causes, it arises still more from the nature of 
 this peculiar rock. It is not even so defined a mass as its 
 kindred and equally unstratified granite, but tb-rows out veins or 
 
 1 ) 3 
 
as Memoirs to H. M. Treasury respecting the 
 
 protuberances in all directions, and in the most irregular mannei . 
 Now as the intervals of these are occupied by the neighbouring 
 rocks, generally secondary strata, the ordinary section formed 
 by the surface of the land produces such an alternation or inter- 
 mixture, that the general boundary, which had been first settled 
 at some’ one point, must be protracted to perhaps even a mile 
 or more at another place, or under another mode of investiga- 
 tion, while it often becomes finally impossible to fix any point at 
 all in a satisfactory manner. In what modes, therefore, the Map 
 may be defective on this point, I need not say, while it is plainly 
 one of the difficulties which cannot be surrnounted. 
 
 There is another difficulty peculiar to this rock, which renders 
 it impossible to give such a map of it, everywhere, as would 
 meet all opinions, and, at the same time, declare the structure of 
 the country in question, for objects of utility. In many 
 it lies visibly over stratified rocks, as, in some of those, both 
 limestone and coal are wrouglit beneath it. This is the case 
 near Glasgow, near Blair Adam, at Clunie, and elsewhere. The 
 ordinary proceeding of a geological map is to represent the sur- 
 face of a country ; nor can it represent such an inferior rock, 
 without either misplacing it or omitting the superior one. I have 
 used both expedients in some cases, and in others have taken no 
 notice of the inferior stratum ; while those who choose to take 
 opposed views will judge all equally wrong. At Clunie, foi 
 example, a limestone appears in the Map as if it occupied the 
 surface, because it is a noted quarry j but it is wrought at a 
 considerable depth beneath the trap. On the north of the Low- 
 mont Hills a considerable breadth is given to the coal sandstone ; 
 but it is chiefly remarkable on the nearly vertical section, where, 
 without this expedient, it would be undiscernible on the Map. 
 And the same expedient, as I formerly remarked, I was obliged 
 to adopt respecting the lias and green sand of the western coast, 
 in many places. 
 
 If I thus also formerly observed, that very minute fragments 
 of strata entangled in trap could not be represented at all in 
 some cases, as, when deemed useful, they are not represented 
 without great exaggeration, other examples of each, besides 
 those which were then noticed, may be pointed out. The slate 
 which appears on the sea-shore, at the town of Oban, is drawn 
 on the sea, since it would have been invisible on the land, unless 
 so far extended as entirely to falsify the trap. A limestone in 
 the trap of the Lowmont Hills is as much exaggerated as that 
 on the shore of Forfarshire, formerly noticed. At Edinburgh, it 
 was impossible to represent the facts at all, in consequence 
 of the smallness of the space, and of the engraving used for the 
 town ; the three junctions of coal sandstone, red sandstone, and 
 trap, all occurring here within a very minute and intricate space, 
 and under the additional difficulties of superposition and veins. 
 They who will look at the white sandstone of the Castle Hill, 
 and the structure about the King's Park, will see that nothing 
 
Geological Map of Scotland. 39 
 
 but a very large draught could have contained the facts in 
 question. 
 
 The last remark which I need offer respecting this rock relates 
 to its veins. In many places, and very notedly among the West- 
 ern Isles and on the western coast, the numbers of these are 
 such, that any visible representation of them would have left 
 room for nothing else. As a general result also, the spaces in 
 question would have been deformed by blue lines on the Map ; 
 while even these would not often have told any thing useful, 
 though dazzling the eye, puzzling the spectator, and troubling 
 the colourist copiers. It is true that I have thus omitted veins 
 which are used as quarries in several parts of the country, and 
 which it might therefore have been desirable to note; but I 
 found that I could not represent even these without the same 
 hazard, and without the farther one of confusing them with the 
 limestones ; since the colour of the ultramarine and of the Prus- 
 sian blue are not always distinguishable on the dark engraved 
 ground, if the spaces are small. And I request particularly to 
 point out this in Lismore, and in the Garveloch Isles, and also 
 at Loch Earn ; where, with all possible care, the limestones of 
 these spots are very difficult to distinguish among the traps by 
 which they are surrounded. 
 
 But after much consideration, I adopted the following general 
 rules respecting the mapping of the trap veins ; and this 1 think 
 it necessary to point out in the present subsidiary explanation of 
 the Map and its Key. 
 
 Every one knows that they abound in the vicinity of the masses 
 of this rock ; and for this reason also, as well as for the former 
 ones, they were omitted. But they were objects of interest where 
 they occurred at a distance from these, as indicating the former 
 presence of trap where it has now disappeared. They have there- 
 fore been marked where they occurred, in this manner, in suffi- 
 cient magnitude or conspicuity to demand such a notice ; while 
 I have nevertheless been compelled to avoid mapping too many, 
 from the conviction that they would sometimes be mistaken for 
 limestones, owing to the reason just assigned, and that they 
 would not attract the notice of persons inspecting the Map, or 
 would be overlooked by the copiers. 
 
 Thus several indications of them will be found to the north of 
 Dunkeld, in Glen Dochart, on the borders of Loch Earn, near 
 Loch Long, and in Strathearn, as well as in some other places ; 
 while, in the latter named tract, their remarkable extent and 
 magnitude were more than sufficient to demand their insertion. 
 
 Of the coal series, and of some other rocks which 1 have not 
 noticed in this enumeration, I have nothing of a similar nature to 
 say ; since the representation at least, whenever one was adopted, 
 laboured under no other difficulties than those which appertained 
 to the imperfect geography of the Map, and to that difficulty of 
 investigation on which I must now make some remarks in addition 
 to those already offered. It was a difficulty that arose from vei y 
 
40 MemoiTS to H. Treasury respecting the 
 
 different causes, as, over very much of the space examined, it 
 must be considered as insuperable. 
 
 Whoever imagines that a perfect geological map of any coun- 
 try can be made, is utterly ignorant of this subject ; as, for the 
 most part, this is believed to be the fact, from seeing maps co- 
 vered with different colours, and making pretensions to be perfect 
 draughts of this nature. Whatever geology may infer respecting 
 rocks, and however these inferences may often be accurate, there 
 is a great deal which can never be known, as far as a perfect 
 geography of rocks is concerned, unless the whole surface of loose 
 materials could be removed, and the earth reduced to its original 
 nakedness. Many things, indeed, which are now doubtful in 
 the present Map, might be coiTected by very simple excavations 
 at some particular points ; since this is to furnish an additional 
 quantity of that evidence whence the actual inferences are drawn. 
 But if the time and expense required for this, even at a very few 
 points, would be intolerable, it is evident that such a wish as this 
 is perfectly absurd, when the w^hole extent of the obscurity is 
 considered. If the common principles of investigation must 
 therefore be followed, it is convenient that I here notice what 
 those are ; that so the nature of the difficulties may be better 
 understood, and that the reasons may appear for here pointing 
 out what I do not know to be correct, and which I have been 
 obliged to lay down under the best conjectures or inferences that 
 1 could make. It is not, indeed, a great deal compared to the 
 whole ; but I will not permit it to be supposed that I desire here 
 to assert, as of fact or knowledge, any thing more than I know 
 or believe to be the truth. In some oi the instances in question 
 this would also be egregious folly ; it would be to pretend to su- 
 perhuman powers, since the eye which could see thus far beneath 
 the surface might equally discern the centre of the globe. 
 
 The obscurity of the superficial rocks arises from the covering 
 of alluvial matter and soil, including peat, which occurs oyer the 
 far larger portion of every country, however hilly, and which, in 
 the flatter lands, conceals nearly every thing. And this is what 
 a geological eye must penetrate in some manner, that it may 
 know how to delineate the rocky structure beneath. 
 
 In mountainous and rocky lands, the exposure of the rocks at 
 certain points is so frequent, that there is, for the most part at 
 least, no difficulty in inferring that which is invisible, by connect- 
 ing these together. Such points are, the fragments of rock which 
 are denuded in consequence of their protrusion above the general 
 surface ; and such also are the precipices of mountains and of sea 
 shores, the occasional fracture and exposure of strata, the beds of 
 rivers, and so forth • while to these must be added such artificial 
 works as roads, quarries, shafts, wells, ditches, and more leading 
 to the same knowledge. Such absolute evidence as is thus ob- 
 tained becomes further enlarged or extended by studying the 
 forms of the ground, though the rocks should be invisible ; since 
 the nature of the rock confers on it a peculiar shape and character, 
 
Geological Map of Scotland, 41 
 
 in many cases at least ; if not universally, nor, always so decided 
 as to produce absolute satisfaction. If thus also, further, the 
 peculiar character of the vegetation often becomes a guide, to an 
 experienced eye at least, it is sufficient that I have thus slenderly 
 noted these more prominent sources of evidence. 
 
 But whatever an attentive and experienced investigator may 
 perform by these means, they are still uncertain, except in the 
 case of stratified rocks, and where those have a marked and also 
 a consistent elevation, with a direction as consistent. The direc- 
 tion then enables him easily to join two such points with truth, 
 or to prolong that which is seen, to places where it is invisible. 
 But if the strata have little elevation, or are much disturbed, and, 
 besides this, uncertain in their elevations, there is no longer any 
 sure guide to be found in their lines of direction ; so that the in- 
 ferences as to what is invisible become difficult or doubtful, with 
 a consequent increase of labour and uncertainty. 
 
 In England, indeed, this is little felt, from the great spaces 
 occupied by each set of strata, and from the absence of the most 
 usual cause of disturbance, namely, the presence of trap rocks ; 
 whence they maintain a great consistency of position and bearing. 
 In Scotland, it is the direct reverse, especially over all those 
 tracts which, consisting of the secondary stratified rocks, possess 
 strata of low elevations, compared to the generally erected pri- 
 mary strata. For the most part, the whole is cut up into small 
 portions ; while the disturbances of the strata are such, that a 
 consistency of position and direction cannot often be traced for a 
 few miles, or even for one ; occasionally, not even for a few yards. 
 This arises from the frequency of trap rocks, as the Map will 
 show ; whence, added to the denudations of the strata or the 
 loss of the superficial portions, it also happens that the inferior 
 red sandstone comes to the surface in the most irregular manner, 
 producing an equal irregularity in the places of the superior, coal 
 series. 
 
 It is seldom possible, therefore, in these cases, occupying a 
 great and most important portion. of Scotland, to infer the places 
 of any thing in the usual manner ; so that the difficulty becomes 
 similar to those which beset the unstratified rocks, granite, por- 
 and trap. 
 
 
 ^ith respect to this last class of substances, it is not here 
 needful to distinguish universally among these three different 
 rocks, in pointing out the general difficulty which attaches to the 
 whole. In the stratified rocks we have always some assurance 
 of a certain continuance or prolongation of that which we have 
 seen, to places where there is nothing visible, and can therefore 
 procure some kind of evidence ; although when the strata are at 
 low angles, and especially if also undulating at the same time, 
 that is by no means always very satisfactory. But in the unstrati- 
 fied, there is none but that which is furnished by the form of the 
 ground ; while the assistance thus afforded is also rare, or can- 
 not be trusted, since the characters which the ground presents 
 
42 Memoirs to H. M. Treasury respecting the 
 
 from such causes are extremely uncertain, and are often variable 
 and contradictory. 
 
 To notice some examples of this, and to commence with gift* 
 nite, that of Scotland sometimes protrudes in peaks, so as to 
 give notice of its place ; in other situations it is in smooth rounded 
 masses with flowing outlines, while these are also deeply covered 
 with soil, so that its extent cannot be either discovered or conjec- 
 tured. In some parts it occupies the highest summits, as I for- 
 merly remarked, and in others the lowest lands. In these last 
 cases, tracts of enormous extent are sometimes little marked by 
 any elevation, and often nearly flat ; while they are at the same 
 time deeply covered with soil, and clothed by trees and cultiva- 
 tion, so as to accumulate one source of obscurity upon another. 
 As an additional difficulty, which, unfortunately, is most fre- 
 quent also in these very districts, there is a frequent intermixture 
 of gneiss with the granite, in a most irregular and often a very 
 minute manner; so that the difficulty of investigation becomes 
 incredible to those who have not seen this country, or one of a 
 similar character and construction. 
 
 In the most favourable cases, therefore, or supposing the gra- 
 nite to be actually and every where visible, its boundaries can 
 only be known by actually surrounding it ; producing, for the 
 most part, an enormous labour when compared to that which is 
 demanded by the elevated strata of the stratified rocks. But no 
 labour can ascertain these boundaries truly when they are covered 
 with soil; above all, where the interchanges of gneiss and granite 
 are frequent, and the country very low or flat. 
 
 This is the case very remarkably in the eastern parts of Aber- 
 deenshire, though by no means limited to those portions of Scot- 
 land. There are miles after miles in extent, where no rock what- 
 ever is visible. It might be safely conjectured, without doubt, 
 in many places, if not in all, from those occasional indications 
 which it is the business of a geologist to discern ; supposing that 
 the granite formed a single and pure mass, or was of a continu- 
 ous extent over a certain tract, great or small. But in the case 
 of intermixed gneiss and granite, being that by which the far 
 larger portion of this country is characterized, and where this 
 peculiar disposition of things arises from the fact that the former 
 is denuded down to nearly the surface of the latter, so as to have 
 left it bare in some places, while it continues to cover the subja- 
 cent rock in others, we can never be sure that an occasional mass 
 is a prolongation from some other place, and not an independent 
 protuberance. And when there are extensive tracts of soil with- 
 out any indications of rocks at the surface, all the labour that 
 can possibly be bestowed still leaves doubts ; as the very best 
 records that can be made may hereafter prove to be erroneous, 
 should future accidents bring the unseen to light. In such cases, 
 it is plain, even the sight of a rock, or even of a space, consisting 
 of granite, offers no security for its existence beyond that which 
 is actually visible ; as reversely, there is equally little proof that 
 
43 
 
 Geological Map of Scotland. 
 
 the visible mass of gneiss may not be the only one present in a 
 tract of this complicated and troublesome nature, where, over 
 miles of ground, nothing but the incumbent soil can be seen, as 
 the features of the land are also obscured by cultivation, and 
 not only that, but rendered inaccessible by the same causes. 
 
 Under these complicated difficulties, or rather impossibilities, 
 rendered still more troublesome by the badness of the geography, 
 there was nothing to be done but either to surrender, and thus 
 to leave the geological map full of blanks, or to fill those blanks 
 with colours denoting the visible alluvia, or lastly, to make the 
 best inferences which the evidence admitted of. I shall imme- 
 diately point out the few places where I have adopted the first of 
 these practices, and also show the reason why. The reasons for 
 not adopting the second seem quite satisfactory, although it has 
 been done to a large extent in the geological map of England, 
 and very often where a due degree of labour would have ascer- 
 tained what the subjacent rocks were. A map of alluvia is not 
 a map of rocks ; so that the real object of a geological survey is 
 abandoned. It is abandoned as a mere question of science, in 
 the first place, and in the next, as a question of utility and appli- 
 cation. The geologist must search these tracts again for his 
 own purposes : and the practical man is left, not merely without 
 a guide, but without a hint respecting the probabilities, to re- 
 place that certainty which possibly could not have been obtained, 
 but which at least has not been attempted under the care and 
 labour that ought to have been applied to such a subject. It 
 would be harsh to call such a practice deceptive, since it pro- 
 bably arises from an unwillingness to leave blanks, where a com- 
 pletely coloured map is expected ; but it is plain that such a map 
 of blanks would be of equal utility with one of this nature, for 
 both the purposes to which I have already alluded. 
 
 But if alluvia are to be entered in the place of rocks, or blanks 
 to be left where those cannot be seen, there can scarcely be any 
 limit placed to this laxity of representation ; as it will always 
 moreover form a ready excuse for withholding due labour from 
 such a survey, or for neglecting it wherever the ground offers 
 any peculiar difficulty. In many parts of Scotland, and especi- 
 ally in the south, above the secondary strata, I have traced miles 
 after miles of alluvial matters, not transported, but the produce of 
 superficial disintegration, as in some places I have ascertained 
 their depths to reach to fifty feet. In other places, extensive 
 plains and valleys are formed of river alluvia, or covered by 
 them, or by blown sand, or by peat, often reaching to enormous 
 depths, or simply perhaps by soil, rendering every thing invisible 
 over large tracts. If any alluvia are to be entered in a coloured 
 record, I know not where the limit can be drawn ; while a geo- 
 logical map would thus become nothing, whatever deceptive ap- 
 pearance of actual investigation it might present to an ignorant 
 eye. The very theory and principle of such a work is, that the 
 naked surface be displayed, as it can best be seen or inferred ; 
 
44 Memoirs to H. M. Treasury respecting the 
 
 and if blanks be left instead of coloured alluvial spaces marked, 
 the work as a geological record, would in reality be just as 
 useful, or rather useless, though in this case at least it would 
 deceive no one by the pretence of doing what it has not per- 
 formed. The work, though essentially as good, presents a defor- 
 mity in addition to its deficiency. j u j t 
 
 What aspect the present work would have presented, had 1 
 adopted either of the systems which I have thus condemned, 
 can easily be conjectured : to myself it would unquestionably 
 have been exceedingly convenient, as it would perhaps have 
 saved nine-tenths of the labour which was bestowed on this sur- 
 vey. But as I should not, most assuredly, have considered this 
 to be what I equally undertook and desired to do, so have I 
 adopted a different proceeding. In all cases of such obscurities, 
 (and they pervade all Scotland,) I have drawn the best inferences 
 which the circumstances permitted, excluding equally, coloured 
 records of alluvial soils, and blanks ; and this in the case of the 
 flatter secondary strata, as well as in the peculiarly difficult one 
 which I have been here pointing out where the intermixtures of 
 gneiss and granite produce such extraordinary difficulties, in ad- 
 dition to those resulting from the depth of the alluvial soil. On 
 the latter occurrence, when in connection with the trap rocks, I 
 must immediately make some specific remarks ; and I will in the 
 mean time point out the blanks which I have designedly left, 
 and the reasons why ; having preferred this to a useless entry of 
 the superficial soil. 
 
 The blank near Kildrummie is the place of a deep peat bog, 
 where granite, slate and red sandstone meet, and in such a man- 
 ner that it is impossible to conjecture how it might be safely 
 occupied with an indication of either of these rocks. In Isla 
 there is a larger one left : although the stratification of the pri- 
 mary rocks to which the rocks in the neighbourhood of this spot 
 belong, is a fact which generally leads to safe inferences ; and 
 that blank is thus left because the disposition of these is here 
 very different from the usual course of things, and will admit of 
 no safe conclusion as to their extension over a very low tract 
 deeply covered with alluvia. 
 
 In Arran there is a smaller one ; and the doubts are still more 
 insuperable in this place, because of the great diversity of stra- 
 tified and unstratified rocks by which it is surrounded. Nor 
 can the truth be ever ascertained at this spot by any thing 
 short of some change that shall bare the whole surface of this 
 valley. 
 
 There is a similar blank near Campbelltown, and for similar 
 reasons; while, especially, I did not choose to lay down the 
 boundaries in this case under any of the usual modes of inference 
 or conjecture, because of the singularity of this tract, and from 
 its importance as an object of utility. Hereafter, doubtless, the 
 pursuits of the coal miners will determine what could not have 
 been conjectured with any tolerable security against error, be- 
 
45 
 
 Geological Map of Scotland. 
 
 neatli the flat maritime alluvium, further encumbered by peat 
 and soil, which occupies this ground. 
 
 The last blanks which I have thought it right to leave, occur 
 near Carse Bay and Southerness Point in Galloway ; and the 
 reasons are similar. AVhoever may hereafter examine the coun- 
 try in these places will perhaps think that I ought to have done 
 the same at the Locker-raoss, at Tents-moor in Fife, in the ill- 
 rescued land south of Stranraer, and in some other places which 
 I need not here specify, as the enumeration would be far too 
 tedious. But at the time I examined those I did not think there 
 was any insecurity in inferring the nature of the rocks beneath ; 
 and a review of those recollections has not induced me to alter 
 the opinions originally formed. 
 
 In proceeding to examine the case of trap under the same 
 views, there are some peculiarities connected with this rock, in 
 addition to the preceding remarks, which demand a separate 
 notice, and which are also independent of those already made 
 on its intricacy, its superpositions, and its veins. Together with 
 the granite, but to a degree very far exceeding that, it constitutes 
 the chief difficulty and labour in the examination and mapping of 
 Scotland : while it is a difficulty scarcely known to England, and 
 as absent from this portion of our island, most materially lighten- 
 ing the labour of a survey of this part of Great Britain. In this 
 there is but very little granite, while it is abundantly conspicuous, 
 and limited to a very few places ; and the limitations of the trap 
 rocks are even more narrow. Nor is it too much to say, that were 
 it not for those two rocks, the survey of Scotland might have been 
 completed in a fifth part of the time which it has occupied, or less ; 
 as the absence of the trap alone would have rendered the more 
 difficult portions of this country a matter of extreme ease. They 
 have in fact constituted the main part of all the labour ; as they 
 have, both, and the latter in particular, led to an extent and 
 minuteness of travelling which might otherwise have been en- 
 tirely dispensed with. There was not a spot of half a mile in 
 extent, towards the north at least, where granite might not have 
 existed, and also have been there undiscoverable, unless close at 
 hand ; while this is even more remarkably true of the trap rocks, 
 if we turn to the south of Scotland. These were literally to be 
 sought for every where, even when it was visible and certain that 
 whole districts consisted of a single stratified rock, with this 
 possible exception, and when they might easily have been map- 
 ped in a very few days, or when nothing more was requisite than 
 to trace their boundaries. Of this, the present Map itself will 
 give abundant proofs, in the scattered, insulated, and unexpected 
 places of those which have been recorded; respecting which, 
 very generally, it is plain that nothing but a minute research 
 could have fallen on them, as in the case of the primary 
 limestones. 
 
 It will be very extraordinary, therefore, if some have not been 
 overlooked and omitted. The allotted time did not allow me to 
 
4G Mcjnoirs to H. M, Treasury respecting the 
 
 examine every thing in this minute manner, over such a wide 
 extent; and it was expedient to apply what was allowed, in 
 ascertaining what could be seen to exist, rather than in searching 
 after what might not ; since the final result might have been 
 a large collection of blanks, and an incomplete work : a work, 
 of which the deficiencies might indeed have been pardoned by 
 the Government, which marked the limit in time which should 
 not be exceeded, but which would not have satisfied the public 
 to whom that restriction was unknown. 
 
 Nor was this all of the peculiar difficulties that attend this 
 division of the unstratified rocks, and which so much augmented 
 the labour of investigating those portions of the country in which 
 they exist. If the character of trap is sometimes so peculiarly 
 marked that it can be known from far, so as to direct the course 
 to its examination, this is very far indeed from being the fact 
 universally. Its masses are sometimes rounded and its outlines 
 flowing, and there are also many tracts in which it is both low 
 and flat, so that no suspicion respecting its presence could exist, 
 as even a closer inspection would often not discover that these 
 tracts consisted of other than the secondary strata which it then 
 accompanies. And not less remarkably, while producing ecjual 
 or more trouble, it is not unusual to find its outline perfectly 
 continuous with, and similar to that of the strata which it ac- 
 companies ; no break or mark appearing to tell that the i ock 
 was changed under our hands, while such change occurs even 
 on the declivities of hills of a continuous form and outline. 
 
 Qui ad pauca respiciunt de facili judicant:” nothing but that 
 mixture of ignorance and conceit which characterizes the gieat 
 majority of those who now aspire to the reputation of this, as of 
 other sciences, will judge to condemnation in this, as in much 
 more that I have here noticed ; while, in the eyes of the enlight- 
 ened and the judicious, it is their criticisms which will form their 
 own condemnations. 
 
 If to what I have thus pointed out, there be added the great 
 depth of soil by which these hills, and especially these junctions, 
 are often covered, still less surprise will be felt at the labour 
 which they have demanded, or at the errors of boundary which 
 may hereafter be discovered ; though it is most certain that no 
 future generations, under any quantity of knowledge and labour, 
 will ever give the true draughts of all these rocks. This depth of 
 alluvia, often especially accumulated in the places of these rocks, 
 from obvious causes, serves also to conceal entirely many of the mi- 
 nuter masses ; as I have been repeatedly convinced by discovering 
 some which had been detected by the cutting of a road, or a 
 quarry, or even a common drain, and where no possible suspicion 
 of their presence could have existed, as, but for such accidents, 
 they would never have been known. It would be unnecessary 
 to subjoin to all this, were it not for the sake of the utterly 
 ignorant, and of those to whom these parts of Scotland are un- 
 known, that these difficulties are enormously increased by the 
 
47 
 
 Geological Map of Scotland. 
 
 cultivation and inclosures of the districts in which these rocks 
 chiefly occur; because it is in those, and as produced by these 
 very rocks, that some of the best and most fertile soils of this 
 country are found. It is not difticult to traverse even the rudest 
 and most remote mountain tracts, though there are no roads ; 
 but the roads on the cultivated ones impede examination instead 
 of aiding it. It is impossible to deviate from them on horse- 
 back, and scarcely possible on foot, owing to the great height 
 and strength of the mclosures ; and the same character pervades 
 all the inclosures of fields throughout almost every portion of 
 this part of the kingdom ; so that while no hunter could contrive 
 to cross or intersect the country, he who attempted it on foot 
 would spend an entire day in making the smallest progress, and 
 ultimately, unless he were singularly fortunate, in doing nothing. 
 No time was allowed for such work as this ; nor indeed could it 
 have been allowed : to survey Scotland in this manner would 
 demand the entire lives of twenty men ; whereas the limitation 
 was to the vei’y few summers, and often short ones, which were 
 occupied in this work, often also but partially, and to a single 
 observer. 
 
 I may now point out a few places, as examples of these facts, 
 before I notice the expedients adopted to represent on the Map 
 that which could not be definitely ascertained. 
 
 If, in the Glasgow district, there are very marked hills of trap, 
 so are there very extensive tracts in which not the slightest indi- 
 cation of this nature exists, and where the rock, when ascertained, 
 is found to be perfectly flat. Even coal is wrought by sinking 
 through these : so that error easily arises by supposing, that 
 where coal is wrought, there must be coal strata at the surface. 
 
 Near Comrie and Cortachy, the trap which every where else 
 occurs in connexion with the secondary strata, is found in the 
 middle of primary slate ; where it would be easily overlooked, 
 since there is no suspicion of its presence in such a connexion, 
 and since it does not well display its characters at a small distance. 
 
 On this northern boundary of the red sandstone it also occurs 
 skirting the slate, in far remote patches, where it is equally un- 
 suspected and difficult to distinguish, unless the observer should 
 have the good fortune to hit upon the very spot, so as, literally, 
 to touch the rock itself. In such cases, it may therefore be 
 easily passed without notice ; since a shower of rain, or the de- 
 viation of a few yards for some other purpose, to examine pro- 
 bably something of striking importance, would render it invisible, 
 or cause it to be overlooked. It is true, that after having once 
 found things so unexpected, I have continued to seek for them : 
 but it would be a singular piece of good fortune indeed if I had 
 not overlooked some, amid all the accidents attending these in- 
 vestigations, and the short time allowed for examinations so 
 extensive and minute, over a country of such extent. I point 
 out, as before, these possible oversights, partly that I may direct 
 others to what may require re-investigation, and partly that no 
 
4U Memoirs to TI. M. Treasury respecting the 
 
 surprise may occur, in case they should hereafter be proved to 
 
 0XlSt» 
 
 The Sidlaw Hills offer a remarkable example of that conti- 
 nuity of outline and form between the trap and the associated 
 sandstone, which, while it is very deceptive, leads to great 
 labour, inasmuch as the rocks can scarcely any vvhere be conh- 
 dently distinguished without an approach amounting to contact. 
 At the western end, the whole elevation of this ridge consists of 
 trap ; towards the middle, it only occupies small patches irregu- 
 larly placed on the surface of the sandstone; and as the ndge 
 proceeds eastward, the trap disappears. Yet the general form 
 and character of this line of hill are very uniform ; so that any 
 surveyor who trusted to these general indications, and to that 
 cursory or general examination which in some cases is sufficient 
 for many rocks, would easily commit error, by prolonging the 
 extent, either of the trap or of the sandstone, accordingly as he 
 had satisfied himself of the one or of the other, by contact ; ac- 
 cordingly, in reality, as he had commenced his investigation at 
 one end or the other of the ridge, trusting after this to his general 
 theory of the peculiar outlines produced by each particular kind 
 of rock. 
 
 Mear Machony, in Stratheara, there is, in this survey, a mark 
 for a patch of trap, considerably exaggerated, for the usual rea- 
 son. Of this fragment there is neither external indication nor 
 change in the character of the ground, to afford the slightest 
 conjecture, as the surface is also deeply covered. The accidental 
 cutting for a deep road has brought it to light. No one can say 
 that hundreds such may not exist, not only here, but throughout 
 the whole of this sandstone district, as in reality there are such 
 ones in Forfarshire. When these are used as quarries, they will 
 be found, for the same reasons as the limestones are; that is, 
 under a supposition that the country people in general are in- 
 formed of them, which is not always the case : so that the sur- 
 veyor who has not the fortune to meet with the actual quariy- 
 men or road-makers to whom they are known, may remain 
 ignorant even of such as are quarried. It is evident that the 
 country might be traversed a thousand times without finding 
 those respecting which there is no information, even though they 
 should be apparent at the surface. Nothing less than to intersect 
 ground as a pointer does for a partridge could detect such things 
 as these, and many more ; as they will be the omissions to find 
 employment for the minute critics of some future day. And if 
 I have not introduced a few, a very few indeed, which have been 
 pointed out to me, it is that 1 have had ample reasons to doubt 
 the accuracy of those reporters. 
 
 If I might easily extend examples of this nature, and of others 
 somewhat different, I will content myself with noticing, lastly, 
 the extreme difficulty of ascertaining, not only the boundaries, 
 but the very existence of the larger tracts of this rock. 
 
 In very many of these, there is aQ interval between the last 
 
Geological Map of Scotland. 49 
 
 visible signs of the trap and the nearest visible ones of the sand- 
 stone, which sometimes reaches to many miles ; whether as this 
 relates to patches of exposed rock or to the general characters 
 of the ground. In this interval the boundary lies ; but the cover- 
 ing is a deep alluvium, reaching, as I formerly remarked, to 
 twenty, and onwards to fifty feet. A surface like this has, of 
 course, no character ; nor is it often that it has been penetrated, 
 either by natural operations or human labours, so as to expose 
 the rock. In general, there are few water-courses in the districts 
 of this nature ; and when there are, they do not penetrate 
 through the alluvia, or, what is nearly universal, they form an 
 alluvial deposit in their channels, from the rubbish they carry 
 along, so as totally to obscure the solid bottom. And it is 
 equally rare to find any assistance in quarries and roads. There 
 is no temptation to quarry through rubbish so deep ; and the 
 roads of Scotland are now so well made, that the artificial cover- 
 ing is as effectual a concealment as the natural alluvium. It is 
 fortunate, in such cases, to meet with an old neglected road, 
 where the rains have bared the surface down to the fundamental 
 rock. 
 
 But supposing that such detached spots should be found, whe- 
 ther those be protuberances arising from the forms of the subja- 
 cent rock, or the seats of water-courses, or whatever else, which 
 serve for the prolongations and definitions of boundaries in most 
 other cases ; they are of very doubtful evidence to the same effect, 
 in the investigation and assignment of masses of trap. They may 
 be veins, or prolongations in the nature of veins, as I had for- 
 merly occasion to notice : while the circumstances already des- 
 cribed render it impossible to decide what they are. Thus must 
 a true definition of these masses be ever a matter of conjecture 
 or chance : since no present labour can ascertain them, as no 
 future one ever will. A specific line or point may indeed be 
 altered, in consequence of some future and more fortunate re- 
 search or accident ; but he who may have detected this error, 
 and thousands more after him, will still be short of the truth ; 
 since it is especially among those facts which can never be 
 known, unless every atom of soil was removed, down to the bare 
 rock. 
 
 A few examples must, as usual, here suffice to illustrate what 
 occurs almost everywhere. 
 
 Throughout the Kilpatrick, Campsie, and Ochil hills, in many 
 places, not only is there an immense invisible interval between 
 the last visible trap and the sandstone, but the change also takes 
 place near the summits or on the acclivities of hills of a uniform 
 shape and flowing outline. There is ever a great temptation to 
 define the trap by the boundary of the hill and plain. Yet this 
 is sometimes proved to be wrong assumption ; since not only the 
 sides but the very summits of the hills sometimes consist of the 
 sandstone, as in the Sidlaw just noticed, and elsewhere, but the 
 trap in other cases runs far into the plain. Under this double 
 
 E 
 
50 Memoirs to H. M. Treasury respecting the 
 
 possibility, it is difficult to know what to do when all marks are 
 
 '^TfToan extent of miles of such alluvial covering the in- 
 terval between ascertained trap and assigned sandstones, ^ 
 he added higli cultivation, trees, dense and lofty enclosuies, a 
 want of roads, and, beyond all, a had geography m the map, 
 the difficulties are enormously augmented. These are facts oi 
 perpetual occurrence in the south of Scotland, while, as usual, 
 
 I may notice a few of this nature as exampffis, in illustration. 
 
 Between old and new Cumnock there is a very remarkable 
 tract labouring under all these difficulties united, as theie aie 
 many more all over that part of the country. For some miles 
 the only indication is a junction of the trap and sandstones no 
 exceeding two or three yards in breadth ; while nothing but the 
 most minute research or the merest accident cou iscovei a 
 which is confined to the gutter of a dirty village. It is one ot 
 thousands of instances to enforce on a geological suiweyoi the 
 necessity of an attention which must not he relaxed for even a 
 yard, aiid of an attention also which must be for ever watching 
 equally the distant and the near: every fracture of a road near 
 him, and the characters and indications of the distant country 
 
 at the same time. . ^ 
 
 In Haddingtonshire, a very extensive mass of assignable tiap 
 terminates on one side in a large space, entirely flat and deeply 
 covered with soil and cultivation. The edges of this are seen to 
 be sandstone ; but there are miles of absolute obscurity between 
 this and the nearest visible trap. The inference has, in the pre- 
 sent survey, been drawn, and the boundary settled, from the 
 evidence of the ditchers, who say that when they meet with a 
 rock over this tract it is trap. It is the best evidence that can be 
 obtained, and yet these masses may be nothing but veins. In a 
 tract between the Glasgow middle road and Slamannan, the 
 evidence of the northern boundary is here taken from some 
 visible masses : yet there is no security that these also are not 
 veins, while there is in this place, a very large space of that 
 alluvial deep nature and total want of all character, whicm gives 
 no evidence of any kind, and may be anything. About Paisley 
 there are many wide intervals without even such doubtful evi- 
 dence as this : not even an atom of rock appearing anywhere, 
 there being no water-course, and neither road, drain or ditch, 
 having ever penetrated to the rock beneath. In a countiy of 
 uniform stratification like England, and in the assured absence 
 of trap, blanks like this excite no doubt and give no trouble. 
 They are laid dow n without investigation, and if with no doubts, 
 so equally with little hazard of error ; while there are thus hun- 
 dreds of square miles which it is totally unnecessary to visit or 
 about which we need not take any concern. In the secondaiy 
 country of Scotland more than every square mile must be nar- 
 row ly examined ; and even when all this is done, to a yard, if 
 that were often possible, we have no assurance of being correct. 
 
 \ 
 
 \ 
 
 \ 
 
Geological Map of Scotland. 51 
 
 If I might long multiply these specific examples, the present 
 must suffice. With what has preceded respecting trap, they 
 form the history of the country as far as this rock is concerned. 
 It only remains therefore to state what I have done on the Map 
 as to the representation of this most troublesome department 
 of it. 
 
 In those first portions of it which were examined for the 
 different purposes directed by the Ordnance, and when there was 
 no intention of making a geological survey, either partial or 
 general, as no idea of such a work had been then entertained, 
 I was content with simply laying down such trap rocks as were 
 perfectly assignable ; using no efforts to extend their boundaries 
 beyond the distinctly visible, by any inference from minute evi- 
 dences. It was sufficient that the former was done : and thus 
 the sandstones occupied spaces at the boundaries which, for 
 aught that I could prove, might equally have belonged to the 
 trap. The new survey, for the present fuller purpose, having 
 taken me to some of those places again, I was induced to re- 
 examine and correct them whenever such reasons for extension 
 could be discovered : and was thence, partially at least, induced 
 to adopt this latter mode of representation more generally, or to 
 carry out the trap boundaries into the sandstone as far as the 
 evidence justified. But where there was no evidence at all, and 
 where therefore it was impossible to find any rule for a boundary, 
 in an interval of some miles, I have not been able to avoid va- 
 cillating betw^een the two modes, during the great number of 
 successive years which have been occupied on this subject, and 
 under the different views and intentions of those two very distinct 
 periods. If the present more recent surveys have therefore also 
 corrected the former one in many places, under these later views, 
 there are others which I could not review in the same way, unless 
 more time had been allowed. 
 
 Hence it will be found, on re-examining the ground, that in 
 some parts the trap rocks are rigidly limited to the visible, while 
 in others they are extended far beyond what is at least obvious : 
 and hence an apparent discrepancy of representation which it 
 has become necessary to explain in this statement ; as essential 
 to the right understanding of this Map, in some points, as the 
 Key itself. And thus also, in as far as errors may, and must be 
 discovered hereafter, they will be of two opposed kinds ; since 
 sandstone may be found where trap is indicated, as, reversely, 
 the latter will be extended into the regions of the former. In 
 each case also, but especially where the trap has been laid down 
 in a detached manner, because it was thus only clearly visible, 
 if the geography is at the same time bad, the errors must needs 
 be considerable, as they will scarcely be corrigible to any pur- 
 pose until there is a new map on which to re-survey the ground. 
 That there are such, I have ascertained, and very strikingly 
 about Dunfermline, where the total omission or perversion of 
 
 E 2 
 
\ 
 
 \ 
 
 \ 
 
 52 Memoirs to H. M, Treasury respecting the 
 
 the forms of a most important tract of ground, as being the place 
 of coal workings, has rendered it impossible to ofter any cor- 
 rection of this Map, unless under a fresh application of time to 
 it which could not he allowed, any more than to so many otiicr 
 
 parts surveyed in the loose manner formerly described, win e ])iii- 
 
 Liing the other and very dilferent objects commanded by the 
 Board of Ordnance. But all this must equally he trusted to 
 future times and future surveyors : as I may now terminate this 
 particular division of commentaries and explanations. 
 
 I must now notice two or three omissions arising from some 
 other causes; while, if it is plain that I cannot name more than 
 1 know of, those which 1 do know should not have remained, it 
 it had been in my power to supply the facts coriectly. 
 
 Since 1 surveyed Caithness, there have been found 
 place, fishes preserved in the usual marly slate: and these doubt- 
 less denote some fresh-water deposit, which, be it what it may, 
 is at least interesting to 2 ;eological science, though it can scarcely 
 possess any other interest. But 1 have not been able to obtain 
 sufficiently correct information about the place, to insert it : ana 
 limitations of time for this survey did not allow me to return 
 
 to so distant a part for so narrow a purpose. , r • 
 
 Between Ballantrae and Girvan there is a small spot of serpen- 
 tine somewhat remarkable from the minerals which attend it, 
 but interesting only to a collector of such minerals. I could not 
 find a o'uide who knew the spot : being on that line m one ot 
 those tracts of bad weather which render everything invisible, 
 and not being justified in waiting for so petty an object, at the 
 hazard of neglecting what was of more importance, nor m atter- 
 wards returning there from a great distance, it remains unnoticed. 
 
 1 mioht indeed have entered it, on report, and perhaps nearly in 
 its rio-ht place: but having never yet found anythiim that was 
 reported to me, correct, when I came to examine it, I have pre- 
 ferred the omission to the probable falsity. 
 
 These are the only omissions of which I am quite sure, m ad- 
 dition to those formerly noticed. But 1 think it very likely that 
 tiiere may be others of a similar nature, relating chiefly to mi- 
 nute spots, and the niceties of boundaries. 
 
 I'o ensure correctness of record, in the only way in which this 
 ever can be done, the necessary portions of the Map were always 
 carried about ; and the entries of outline, and generally of colour 
 also, were made at the time of observation, and on the spot. 
 Thus did those segments frequently receive much injury from 
 wet and friction,; as the unavoidable wear at the angles of the 
 folds often interfered with the most intricate spots, numerous as 
 these are over so much of the country. It was quite impossible 
 to replace such a damaged portion with a new one whenever that 
 might have been desired, though it was always done when it was 
 practicable-; and as the damage did not perhaps occur till weeks 
 or months after the entrv, and when the ground had been left far 
 
/ 
 
 Geological Map of Scotland, 53 
 
 behind, it was impossible to re-survey it for that purpose, and 
 necessary to re-copy it in the best manner that was admissible 
 and probable. 
 
 It was necessary further to re-copy the parts of this Map, some- 
 times to the extent of nearly the whole, repeatedly, partly from 
 the cause just described, and partly from the corrections which 
 fresh surveys of the same ground introduced. 1 find that even 
 the great practice of the professional colourists does not enable 
 them to do this with certainty, without the aid of an engraved 
 outline, which I had not ; so that some errors have probably 
 occurred from this cause, in addition to all others. It is very 
 true, that even the comparison of the copies does not easily de- 
 tect them, else they would not have occurred ; but they may still 
 be errors as to the ground itself, when that is minutely compared 
 with the Map. Under such an attempt at accuracy as pervades 
 the latter portions of this work at least, and many portions of 
 the former, early, surveys also, where the boundaries are closely 
 referred to some geographical point or line, an error of the six- 
 teenth of an inch in the colouring will throw the boundary a 
 tluarter of a mile out of its place, so that they who seek it on 
 the ground may often be disappointed at discovering that it is 
 not there, or by finding that it is on the wrong side of some road, 
 or river, or house, or other solid object in nature. If under the 
 two causes just described, damage and re-copying, there are such 
 errors, as cannot fail to be the case, it is plain that they were 
 among the unavoidable ones, and however to be regretted, not 
 matters of self-accusation. Nor, like all the rest, can they ever 
 be avoided unless, with a better geographical survey and a far 
 larger scale, many persons were employed on such a work, with 
 an absolute command of unlimited time, and every convenience 
 that such persons could desire. And I may further remark, that 
 above all it would be necessary to be unlimited in places of rest 
 and accommodation ; or to carry on the work, as much of a future 
 geographical survey of Scotland must be, under a system of en- 
 campment ; demanding of course far other numbers and means 
 than those allotted for the present work, and to which it was con- 
 fined. The enormous distances which intervene between places 
 of accommodation in many parts of the country, render it often 
 impossible to bestow the requisite attention on the intermediate 
 and surrounding portions, even with the rapidity which a horse 
 afiPords ; as there are also many which cannot be traversed in 
 this way ; and I need not say that the nights cannot be passed 
 on a Scotch mountain. He who will merely inspect the Map, 
 may form a tolerable conjecture of all this, if he will at least 
 measure the parts by a scale of miles, and if sufficiently ac- 
 quainted with any one portion to estimate what the others are : 
 but no one who has not gone over the ground itself can truly 
 know what it is, while even the Alap will deceive him as to its 
 facilities. Very many of the roads laid down in the Map, are 
 roads which were intended, but never made: many more havo 
 
 E 3 
 
54 Memoirs to H. M. Treasury respecting the 
 
 ceased to exist, and there are still more, which, so far from being 
 roads, as they are marked, are nothing more than the lines tra- 
 velled by droves of cattle, which over immense spaces every- 
 where, are quite invisible, and known only to the experienced 
 drovers themselves. And to add to all this deception, the new 
 system of sheep-farming has entirely dispersed or destroyed 
 thousands of houses and petty villages; so that where we expect 
 to find those which are marked on the Map, we meet nothing 
 but an absolute desert, not seldom extending over many hundred 
 square miles. 
 
 I have thus explained as fully as the necessary limits of such 
 a commentary permitted, the several reasons why this Map is 
 not, and could not have been, a perfect work ; if at least there 
 is any one ignorant enough to suppose that a geological map can 
 be what a geographical one is ; that what can very seldom be 
 seen, but must be inferred from a variety of obscure evidence, 
 can be delineated with the same truth and precision as that which 
 lies open to sight. But this would have been unnecessary had 
 I been content to make this work such as all geological maps 
 have hitherto been. I have assumed, not merely a higher stand- 
 ard, but one that I knew to be unattainable. Yet it thus also 
 I have effected more than ever had been done before, so have I 
 rendered more apparent that which was not done ; sometimes 
 because it could not, and never will, and at others from the differ- 
 ent collateral impediments already pointed out. Of these, the 
 one chief obstacle consisted in the want of adequate time and 
 means, when compared with the intricacy and difficulty of the 
 geology, the difficulties arising from trackless and uninhabited 
 districts, or places otherwise difficult of access, where freedom 
 of access was most needed, and those which were produced by 
 bad weather ; extremely prevalent in most parts of Scotland at 
 all times, even in summer, unusually prevalent during many of 
 the seasons in which this work was carried on, and, in this hilly 
 country, having the effect of obscuring the whole ground, so as 
 frequently to render invisible or unintelligible, everything which 
 could not be almost brought within reach of the hand. 
 
 To the other leading obstacle to greater perfection I formerly 
 alluded in relating the origin of this Map ; so large a portion of 
 it having been arranged in the best practicable manner from se- 
 parate surveys, made without any such ultimate views, and, as 
 being made without any command from that Department which 
 ordered very different examinations, never attempted where it 
 could have interfered, either in point of time or expenditure, with 
 the work which was commanded ; while to this I may also add 
 that very large portion which was executed under leave from the 
 same Department, without any expenditure of the public time or 
 the public money. No work, thus executed, and thus finally com- 
 piled into one whole, could be other than the present one is : but 
 it is the best which the circumstances permitted, and as such it is 
 now presented to that Department of the Government which] uclged 
 
55 
 
 Geological Map of Scotland, 
 
 it better that the whole should be finished in the best admissible 
 manner, than that the original detached surveys should be lost. 
 
 If I had not desired that this work should not pass for a bet- 
 ter or more accurate one than I know or believe it to be, and if 
 I had not desired to point out the very deficiencies, in the hopes 
 of such specific corrections as might lead to a future and better 
 work, I should not have made this commentary what it is ; but 
 have followed the general usage, and also adopted the conve- 
 nient one of using a map less crowded with geographical marks, 
 since it is through these alone that errors can be detected. But 
 for these reasons also, I need not have become the critic of my 
 own work ; being certain that very few of the errors and omis- 
 sions which 1 have pointed out would ever have been discovered 
 by others, and that it will not be known, perhaps for a century 
 to come, how far the entire work is correct or incorrect. 
 
 If any corrections shall hereafter be offered, I shall gladly 
 adopt them when they relate to visible and demonstrable facts : 
 yet they must have other authority than such as has already 
 been offered, though but in a few cases ; since an examination 
 of the facts has always compelled me to reject those suggestions, 
 and consequently all others coming from the same and similar 
 authorities. But there is no reason why I should receive as cor- 
 rections, that which is matter of inference and opinion, any more 
 than that I should adopt the suggestions of system and hypo- 
 thesis for truth. It will be time enough to do this when I have 
 found that such persons are more worthy of dependence than 
 myself, and of more experience iij the difficulties and the geolo- 
 gical arrangements of Scotland. If in the only part where this 
 Map enters into collision with geological maps of England, there 
 is a want of agreement on the two sides of the common bound- 
 ary, it will be for others to see whether they may not be in the 
 wrong, where I have laboured to be right, and could find no 
 reason for rejecting my own investigations. 
 
 In concluding, I think it necessary to inform that Department 
 of Government which adopted the original surveys and completed 
 the whole in its present form, that petty criticisms and correc- 
 tions will be made by those who will find it abundantly easy to 
 do this, by bestowing on a single spot, and perhaps at their own 
 doors, under every convenience of place and time, the labour which 
 I was compelled to diffuse in the same time over hundreds of miles, 
 and under a privation of all conveniences. These will also be used 
 to discredit the whole work : but the discernment of that Depart- 
 ment, thus forewarned, will easily see that they ought not to have 
 this effect, even when the corrections are unquestionable, as it is 
 very certain that they will not always be such, and as they will 
 be the produce of those persons who, already with ample leisure, 
 through a long series of years, to examine the unknown parts of 
 Scotland, have only employed themselves in re-examining what 
 they were already taught by myself to see and know , much 
 more often failing than succeeding in correcting anything of all 
 
60 Memoirs to H. M. Treasury respecting the 
 
 that which they could not discover, and dared not attempt, before 
 it was pointed out. It is twenty years since this work has been 
 in hand, in some manner or other ; and since, in all that time, 
 not one geologist has made a single contribution to the kn^- 
 ledge of Scotland, with the exception (I must repeat it) ot Ur. 
 Hi&ert, the Lords of the Treasury will the better know how to 
 value the impending criticisms of such men. They will the be^ 
 ter know this also, being fullv aware of the conspiracy which 
 was originally formed against' it, which has been unremittingly 
 pursued throughout, and recently with unusual means, and in- 
 
 creased energy. i . 
 
 But as all this must finally recoil on men and motives too un- 
 worthy to notice, far more to name, I request the Lords of the 
 Treasury to observe, that I should not have indulged m mese 
 remarks but for the duty I owe them : that I may guard them, 
 whether from their own suspicions, or the accusations of others, 
 respecting this work, and the prudence of their proceedings in 
 adopting that which was offered to them as a basis, and in con- 
 ducting it to the present termination, through the present hands. 
 Let it hereafter prove what it may, it is the first and only work 
 of such a nature and extent that has been executed by a single 
 hand, and with even an attempt after accuracy. 
 
Geological Map of Scotland. 
 
 57 
 
 NOTICE 
 
 RESPECTING 
 
 THE GENERAL DISTRIBUTION AND CHARACTERS 
 
 OF THE 
 
 ROCKS OF SCOTLAND, 
 
 AS THEY ARE REPRESENTED IN THE MAP. 
 
 THE purpose of this notice is to state some facts relating to 
 the rocks of Scotland, which could not be represented in the 
 Map, as they are matters which no map can show. With the 
 other accompanying explanatory notices, this one will complete 
 the plan which was intended, and which the nature of this survey 
 seemed to demand, as to that it was properly limited. It is a 
 needful sketch, but no more. 
 
 In a former publication on the Western Islands of this coun- 
 try, I have given a specimen of what a work on local geoloo-y 
 ought to be; including, with the topographical details, aiidthote 
 also under great minuteness, all those philosophical views and 
 reasonings from the ascertained facts, which bear on the science 
 of geology : as that work has also rendered geology a far other 
 science than it was before I undertook this subject. Much of 
 what It contains, both as to the facts themselves and the reason- 
 ings from them, will equally bear on the far more numerous facts 
 vyhich the continued survey of the whole country has brought to 
 light ; though there are many more which might have been de- 
 tailed for the same and other objects, exclusively also of what 
 will be found in my other various writings on the same subject 
 But my Lords Commissioners do not expect a work of this 
 nature and magnitude ; any more than they have ordered what 
 could not be in their contemplation : while there are ample rea- 
 sons, already alluded to in another report, why I should not 
 undertake it on any other grounds. It will suffice if this sketch 
 renders the geological structure of Scotland more intellicrible 
 than the mere Map would have done. ° 
 
 The total structure of Scotland differs considerably from that 
 of England. It contains a much larger proportion of primai-y 
 rocks ; and while it possesses a comparatively inferior quantity 
 of the secondary strata, so are these much more limited in kind^ 
 It also abounds in the trap rocks, as these form a very character- 
 istic general feature belonging to it ; while, in England the 
 limitation of these is very narrow. ^ 
 
 If, for the present, 1 keep out of sight those very small por- 
 tions of strata, from the coal series upwards, which are found on 
 
58 Memoirs to H. M, Treasury respecting the 
 
 certain parts of the eastern and western shores only, and in a 
 quantity so small that they are scarcely visible on the map, it 
 may be considered that the secondary strata of Scotland termi- 
 nate upwards with the coal series. This is consequent y the 
 uppermost rock (or deposit), of Scotland, in geological order as 
 well as in geographical position. Nor is it anywhere covered by 
 superior strata, since it does not exist where the very limited 
 portions of these occur. Thus may every secondary stratum 
 above this, which is found in England, constituting so large a 
 portion of this part of the Island, be deemed wanting in Scot- 
 land. Of the exceptions just noticed, 1 shall give the needful 
 
 details hereafter. i 
 
 If the primary strata, or rocks, display therefore every rock 
 which is known, or at least truly ascertained to be a distinct 
 species in geology, the secondary strata are limited, always under 
 the preceding trivial exceptions, to the old red sandstone, the 
 mountain limestone, and the coal series. It has been said, or 
 thought, indeed, that the magnesian limestone, which is supe- 
 rior to the coal, occurs in this country. This is very possible, 
 since it might as well be present, in detached places at least, as 
 the fragments of the strata superior to it just noticed. It is 
 equally possible that indications of the former existence of strata 
 much superior, even to the very chalk itself, may be some- 
 where present, since it is very plain that the suiface of Scotland 
 has been widely and extensively degraded and removed. But 
 such indications of the latter as flints afford, are questions for 
 philosophical speculation, not matters for this Map, or for the 
 explanations belonging to it. 
 
 As to other relics or evidences of superior strata, I have noticed 
 them on the Map wherever that was possible. But I have never 
 seen an unquestionable piece of the magnesian limestone. I do 
 not dispute that it may exist, or may not even have been found 
 and proved : but that which has been shown me as such was 
 not; and I can have no respect to the imaginary authorities 
 which see England wherever they go, because they know nothing 
 else, and which equally represent the old red sandstone of Scot- 
 land as the red marl. The positions assumed by the rnountain 
 limestone and its associates among the coal strata are often very 
 extraordinary, in consequence of the disturbances created by the 
 trap rocks ; while the influence of these is also such as to obli- 
 terate all traces of shells, and to entirely change the characters 
 of the limestones, even to the conversion of them into white 
 marble, and further, into rocks which are undistinguishable in 
 the hand from the magnesian limestones of England. The geo- 
 logists who decide on such limestones, must first learn to know 
 Scotland, and their own subjects also, better ; and I must also 
 acquire a far other confidence in their knowledge, discern- 
 ment, and love of truth in preference to hypothesis, before I can 
 accept of their authorities, or of the authority of any man known 
 to me for anything which relates to this country. They did not 
 
Geological Map of Scotland, 59 
 
 even know the important facts respecting limestones, just noticed, 
 till I pointed them out, as it has been my fortune to inform 
 them of far more : of much which belongs to geology at large, 
 and of everything which they know of Scotland : yet it was 
 under this ignorance that they have decided on the characters 
 of these strata. At any rate, let this, as a matter of geological 
 curiosity, and of exceedingly insignificant moment at the same 
 time, remain for future examination and decision. 
 
 I have said that Scotland gives striking marks of having 
 undergone a great waste of its surface. Others may speculate 
 on what has been lost, if they hesitate between the two suppo- 
 sitions, namely, that the superior strata of England never existed 
 in Scotland generally, and that they have been removed. Such 
 inquiries exceed my bounds : but I may note the chief places 
 vvhere there are conspicuous indications of the loss of the supe- 
 rior rocks, stratified or unstratified. 
 
 This is very remarkable in Sutherland and part of Ross-shire, 
 with respect to the red sandstone, where the evidence can be 
 traced, even in many parts of the Map, and in some sections for- 
 merly given in the work to which I have alluded. The detached 
 fragments indicate a former much wider connection. 
 
 It is perhaps even more remarkable in the districts occupied 
 by trap ; the chief of which extends from the primary territory of 
 the Highlands to that of the south of Scotland, as the smaller 
 one is found to the south of this southern slate. The disjunctions 
 of the masses, and the scattered small patches, bespeak a former 
 far greater continuity, if not a complete one : while the reality, 
 of the destruction at least, is proved by the presence of trap soils 
 covering the sandstones. 
 
 But perhaps the most remarkable traces of extensive waste 
 occur in Aberdeenshire. Towards the west, very generally, the 
 mountains are high, as the schistose rocks rise to high elevations, 
 and appear to conceal much granite which would otherwise be 
 visible. In this eastern portion of primary territory, the same 
 rocks appear to have been worn off to the granite ; thus display- 
 ing considerable, and often very low tracts of that rock. Thence 
 also does the direction of the stratification lose all regularity : 
 and thus, if also from additional causes elsewhere noticed, does 
 the investigation of this portion of Scotland become so especially 
 difficult. 
 
 This may suffice as to the changes in question : as it is out of 
 my limits to detail the alluvial condition of Scotland, with all of 
 the various and interesting matter which belongs to it, while it is 
 also matter for a volume : and for this reason, therefore, I make 
 no remarks on the changes which have occurred, and are still 
 taking place, on the sea shores of this country more especially. 
 
 In the following sketch of the details of the several rocks, 
 T shall take them in that order which is the usage of geology, as 
 far at least as that can be done where there is no constant order 
 among the primary schists, and where there are some rocks which 
 are guided by no rules whatever. 
 
(50 
 
 Memoirs to H. M. Treasury respecting the 
 
 A glance of the eye will show where the granites of Scotland 
 lie, and what is their extent. Except in Aberdeenshire, it is not 
 very great in any one district. It occupies, indifferently, some of 
 the highest and some of the lowest grounds; and this is equally 
 visible on the Map. If sometimes found in considerable tracts oi 
 large patches, it also occurs in exceedingly minute ones, as 1 
 formerly noticed, and as the Map will show. In such cases, its 
 occurrence is of course unexpected, and thus, as formerly said, 
 must the discovery be often accidental. But it is equally ^nex- 
 where it covers larger spaces ; and tins 
 
 pected in some places where it covcts larger spa 
 is perhaps especially remarkable near Comrie. Where the schists 
 are bared down, as in Aberdeenshire, nothing of this nature ex- 
 
 It occurs in contact with every primary stratum in the system , 
 but the Map and the sections jointly show this m such a manner 
 that I need not detail it in words ; as my plan excludes the 
 thousands of interesting geological facts which are found at those 
 junctions. It is more remarkable, that it is immediately followed 
 in a few places, both by the red sandstone and the has series, as 
 will also be seen in those records : while, as to these, I must also 
 suppress equally the details that interest geological science. 
 
 It is not within my limits to point out its external characteis 
 and interior disposition in any place where it occurs, however 
 different those may be. Details of this nature demand much 
 room, and also much collateral discussion; and they cannot be 
 adopted in one place, or for one rock, unless they were extended 
 to all, with the consequent production of that large work winch 
 must not be produced. And as the general geological conclusions 
 respectinsT this and all else that Scotland displays are stated in 
 my System of Geology, as some of the facts are in other writings, 
 this proceeding is the less necessary. If the details, indeed, of 
 all these things would form a more full system of philosophical 
 geology, so would they furnish the facts in evidence. But while 
 this cannot be, the Map will at least form a guide to those facts ; 
 and they who are desirous, will be able to verify them. 
 
 It would be beyond the limits of any work to notice the mine- 
 ralogical variations of these granites, and utterly out of the plan 
 of this sketch. It would be the mineralogical history of granite ; 
 and of that I have given enough in my system of rocks ; as I 
 have shown, in other writings, its transitions into ordinary green- 
 stones and basalts, especially remarkable in Aberdeenshire and 
 Shetland. I must equally suppress the details of some facts 
 which seem to distinguish the granites of Scotland into three 
 principal mineralogical divisions i they are not suitable to this 
 sketch, and would lead into inadmissible details. And equally, 
 therefore, must I suppress the facts which prove the successive 
 productions of these different masses and kinds, while also giving 
 an insight into at least their comparative ages. 
 
 On the economical application of the granites of Scotland, I 
 must nevertheless make some remarks, both as these concei n 
 then mineralogical nature and their geography under view^s of 
 
Geological Map of Scotland. 61 
 
 commerce. But I shall, of course, limit these to what is practi- 
 cable : it would be fruitless to give an account of things which 
 their situation will for ever preclude from being objects of appli- 
 cation to the purposes of life. 
 
 The red granites are more durable than the white, as a general 
 rule. The granites which contain hornblende are more durable 
 than those which contain mica ; and those which contain white 
 mica are more durable than where the mica is black. If the 
 latter is also abundant, the chance of durability decreases. There 
 is a variety of granite containing a felspar exceedingly subject 
 to decomposition, apparently from containing an unusual propor- 
 tion of alkali. The granites of Cornwall are frequently of this 
 character, and are not durable. They even decompose exten- 
 sively in nature, and the felspar forms similarly extensive masses 
 of porcelain clay. Though beautiful to the eye, the perishable 
 nature of these should cause them to be rejected, especially for 
 bridges. 
 
 As far as I could trace and examine, the granites of this latter 
 character are rare in Scotland ; they occur, however, in the inte- 
 rior flat parts of Aberdeenshire, where they are also often 
 exclusively decomposed into gravelly clays. But I could find 
 none of these which even washing would render fit for the manu- 
 facture of porcelain, since they were all too deeply impregnated 
 with iron, arising from decomposed hornblende. It is stdl pro- 
 bable, however, that such examples may be found : and they 
 who intend to seek, will now at least know where to search. 
 
 Granite of a similar character occurs on the great ridge south 
 of the Dee ; but is far from universal. On the contrary, these rocks 
 contain the most numerous and beautiful varieties, within a given 
 space, that I have seen in Scotland, and with every promise of 
 durability ; as the texture of many offers also great facilities in 
 w^orking. It is for architects to judge of the value they may 
 attach to mere beauty. It is for commerce to judge whether 
 granite could be profitably transported from these spots to the 
 sea, as might possibly be done by uniting that transportation with 
 the rafting of the timber of those places. In the mean time, the 
 vicinity of the present Aberdeen quarries to the sea renders it 
 unlikely that more distant ones will be opened; as there are also 
 some places which afford a grey, small-grained stone, leaving 
 little to wish in point of beauty or facility of working ; as the 
 buildings of Aberdeen testify. 
 
 If I have observed, as a general rule, that the granites con- 
 taining hornblende are the most durable of all, and that they 
 are most so as the hornblende prevails, so have they other quali- 
 ties, little iioticed, which give them a great superiority to the 
 others. It is a pure folly to inquire of the strength of a granite to 
 bear weight, before using it in architecture, since the weakest will 
 bear far more than is ever required. It is the tendency to decom- 
 position which ought to be the object of inquiry ; and no time or 
 weather ever appears to make impression on the granites of this 
 
02 Memoirs to H. M. Treasury respecting the 
 
 composition. They are also the toughest kinds, and nearly 
 among the toughest of stones: whence they are peculiarly fitted 
 for paving, or, in defect of the even tougher traps, as materials 
 for roadsf But they have another very valuable quality as archi- 
 tecture is concerned. By the hammer alone they can often be 
 broken into forms nearly as true as the pick would produce ; 
 and thus also, even flat faces of many feet square are often the 
 consequences of the blast of gunpowder. The value of this 
 quality in the saving of labour needs not be dwelt on. 
 
 Many parts of Aberdeenshire, especially in the open interior 
 districts, abound with granites of this nature; they occur, in- 
 deed, so generally in Scotland, that there is scarcely a place 
 where they will not be found ; but, after the tract mentioned, 
 they seem to abound principally in the granite district, of which 
 Cruachan and Rannoch may be taken as the measure. 
 
 I need scarcely point out that the accessible granite of the 
 shores of Galloway offers easy resources, in a great variety of 
 this rock, and of very perfect qualities ; since it is now brought 
 near Builtte, for the uses of Liverpool. And if the Map will 
 show where the other granites of Scotland are well situated foi 
 commerce, I need not extend these remarks on their qualities 
 much further; since I have endeavoured to supersede the neces- 
 sity of such enumerations, by a statement of the principles ol 
 judgment respecting them. 
 
 But I must note here the red granite of Mull, the general 
 quality and aspect of which are well known from its use m the 
 ancient buildings of Iona. On the northern shore of the Ross 
 of Mull, in particular, it is distributed in such a manner, and in 
 masses so large and so free from fissures, that it would be easy 
 to extract from it columns of any desirable dimensions; to 
 twenty, thirty, or forty feet easily, and I doubt not, to fifty or 
 more : while its proximity to a shore abounding in shelter and 
 readily accessible, almost even to contact, by small craft, would 
 render the shipment as immediate and easy as shipment can well 
 be. Should stones of this dimension ever be required, architects 
 will now know where to find them, in a granite equal in beauty 
 to that of Egypt. 
 
 I believe that I need not detail the other remarks which 
 I made on this subject : since, of many, the commercial difficul- 
 ties were too great ; as this enumeration will also apply much 
 more widely. 
 
 The gneiss of Scotland occupies a larger space than any other 
 rock, primary or secondary, as it also forms the most extensively 
 continuous tract. With this, and the showy colour applied to it 
 on the Map, its whole extent will be immediately visible. It 
 will also be seen that it is limited to the northern division of the 
 primary rocks ; no trace of it having been found in the southern 
 one, even in the immediate vicinity of granite. But it is not 
 always easy to delineate it truly, as I have elsewhere noticed, 
 from its gradations and intermixtures : while, in some places, its 
 
Geological Map of Scotland. 63 
 
 disposition is so contrary to expectation, that unless the Map 
 should in these parts be supposed erroneous, the observer is 
 always haunted with the disagreeable impression that he may 
 not have discovered the truth, as these anomalies also lead to 
 a great increase of labour in the investigation. The followin<>' 
 sketch of its disposition will explain all this more fully than 
 I could have explained it in a preceding notice. 
 
 The general direction of the primary strata of Scotland, when 
 at all regular, is upon a line vacillating to the northwards of the 
 north-east rhumb line: and such, ot course, is the direction 
 of the regular beds of gneiss. The geographical natural section 
 of the land in which the Caledonial Canal lies, is a convenient 
 reference for the course of the strata in this part ; as the great 
 slate belt extending from Arran to Stonehaven forms another 
 convenient object of the same kind, though under a want of 
 parallelism which, it must be believed, cannot depend on the 
 Map, since it would imply a scarcely-possible geographical 
 error. 
 
 Where this direction is regular, it is also, generally, but not 
 universally true, that the dip is to the south-eastward, but under 
 a great diversity of angles, independently of those peculiar and 
 well-known disturbances in this respect which occur in the 
 vicinity of granite. If I have not elsewhere mentioned the gene- 
 ral average which might be assumed for these angles, pointing 
 out the impossibility of representing them, even in a small num- 
 ber of places, as they really are, 1 may here say that they range 
 most generally from twenty to fifty or sixty degrees, as they are 
 also occasionally much nearer to the vertical. 
 
 It would be endless to enumerate the places in which the gneiss 
 follows this consistent direction and dip, even where those were 
 observed ; while there is much that is inaccessible to this species 
 of observation. Nor would it be of any use: it will suffice to 
 state the facts in a general manner. Nothing can be more idle 
 than these inquiries about position, unless in the case of work- 
 ings, especially among the secondary strata : since they are so 
 variable that a hundred records of lines and angles would often 
 scarcely express the truth respecting as many hundred yards, 
 especially among the primary strata ; while there is perhaps not 
 a thousandth part of all those rocks where any observation 
 whatever of this nature can be made. To be thus anxious about 
 such matters, is of the petty pursuits and follies of a speculative 
 ignorance in geology. 
 
 If I except that portion of Aberdeenshire which includes Fraser- 
 burgh and Lochell to the Dee, forming its eastern and generally 
 low division, and again draw an irregular line between Strathy 
 Head and Loch Enard, the directions and the dips of the gneiss 
 may be said to follow a regular order with tolerable consistency. 
 Not but what there are occasional anomalies, even independently 
 of the immediate presence of granite : though it is impossible here 
 to enter on so fruitless and necessarily imperfect a detail. One 
 
(54 Memoirs to II. M. Treasury respecting the 
 
 only I may notice in Glcnco, where the strata are vertical, al- 
 though tlie granite is somewhat remote ; while this, and the 
 peculiarities of mineral character in this spot, seem to depend on 
 
 the abundance of porphyry veins. -c j r • • *i * +i 
 
 But it is even in this regularly stratified division that theie 
 occurs the great anomaly to which I have just alluded. In most 
 cases there is some parallelism, if not always very accurate, while 
 never so prolonged as it is between the mica slate and the clay 
 slate defining the gneiss and the next stratified rock in the same 
 class - or the changes of the rocks occur according to the order 
 and repetition of the strata. But the Map will show that m some 
 places this rule is broken ; being that cause of surprise, and also 
 at first of doubts, in those tracts, which it would not have been 
 where the positions of the gneiss are irregular. The change 
 from the gneiss to the mica slate occurs on the line of the direc- 
 tion of the strata ; and while 1 here point out the district near 
 Ben Nevis as a conspicuous example of this fact, the Map will 
 show where else it occurs, both with respect to this substance and 
 to quartz rock. In the eastern parts of Aberdeenshire, where 
 it happens with respect to clay slate also, it excites no surprise, 
 since all the primary strata equally have ceased to possess any 
 
 consistency of direction. , , , • x x j 
 
 The dips here are also equally irregular, both in quantity and 
 tendency : there is no order of any kind ; and thence the diffi- 
 culty of investigating the places and the boundaries of that 
 which, in addition, is also often invisible. Nothing can be in- 
 ferred, but all must be examined and surrounded, with the same 
 labour which the unstratified rocks require. There is little doubt 
 that this distribution must be referred to the proximity of the 
 granite. It is what takes place everywhere in those circum- 
 stances ; but the visible space is unusually large. 
 
 In some parts of the north-western angle of Sutherland, and 
 there at least most remarkably, the direction of the gneiss re- 
 mains sufficiently constant, but the dips are reversed; the strata 
 being nevertheless as regular as usual. Of course, vertical po- 
 sitioL also occur between the western and the eastern dips. 
 
 But further south in the satne quarter, all regularity disappears, 
 under an utter confusion of dips, positions, and curvatures. 
 this character prevails very generally through the outer chain of 
 islands ; as also in Tirree and Coll ; in which islands also it 
 chiefly is, that we must seek those singular and extravagant 
 curv'atures which the gneiss of Scotland so often exhibits. 
 
 Besides the changes of the gneiss on the line of direction, it 
 is subject to others which, as I already noticed, materially en- 
 hance the difficulty, first of ascertaining and distinguishing it, 
 and next, of mapping it, even when it is ascertained. 
 
 It passes into quartz rock and into mica slate, according as it 
 approximates to these. Such gradation is easily traced in sepa- 
 rate masses or specimens ; but that is far from being the case in 
 nature, because the rocks about the places of these changes are 
 
Geological Map of Scotland. C5 
 
 ofteu invisible. There is nothing however in this, as far as scien- 
 tific geology IS concerned, which it is not prepared to hear • nor 
 IS aught more than the general fact of any moment. But it also 
 IS interchanged occasionally with both of these rocks, in suffi- 
 ciently thin alternating strata, and often over large spaces, as 
 ^ig t lave been represented, at least under some exago'eration 
 by ineaiis of sections, since that could not be shown on the Map! 
 J\ either in this is there any geological wonder ; and as to all else, 
 the accurate determination is a matter of indifference. Such 
 changes are of frequent occurrence in all the rocks of this divi- 
 sion, not even excepting the limestones, where almost every 
 other schistose stratum is found similarly altematino- with the 
 calcareous beds. o 
 
 This IS all which I think it necessary to notice respecting the 
 position and the connections of the gneiss in Scotland, in addition 
 to what the Map will show. I presume it is scarcely necessary 
 to say, that it is followed in immediate contact by every rock in 
 the series, down at least to the red sandstone ; since this is suffi- 
 ciently visible on the Map. 
 
 o endless to detail all the varieties of gneiss 
 
 which Scotland presents, I must limit myself to a general sketch 
 u ’ while the book already mentioned, founded 
 
 chiefly on a collection of these varieties, as far as that rock is 
 concerned, will give every minute detail which could not be in- 
 troduced here. 
 
 Though I have made other divisions in that work, I need here 
 notice only the granitic and the schistose ; since they are the 
 only ones in which either geology or statistics can take any inte- 
 rest while the laminar ones may also rank with the schistose. 
 
 Ihe granitic varieties are so universal over the outward chain 
 of islands, including Tirree and Coll, that it would be difficult to 
 hnd any other. They occur also, abundantly, in Aberdeenshire 
 and dovvn to the border of the primary territory in this quarter! 
 Generally also they may be said to predominate over the o-reat 
 western divisions of Ross and Inverness, as they are equally the 
 most abundant in Sutherland. But if they also are found almost 
 everywhere, there are one or two general rules under which they 
 may be expected ; as those rules include some places which ! 
 need not here distinguish. Wherever there are numerous and 
 conspicuous curvatures, the gneiss is granitic : and it is the same, 
 with little exception, where the positions are irregular. It is the 
 same also, almost universally, where the beds are in the vicinity 
 of granite. ^ 
 
 On the contrary, extensive and regular prolonged beds are 
 very generally schistose or laminar ; as the strata also are of this 
 character when alternating, and continuous, with mica slate and 
 quartz rock. Thus it is, that the great tracts of this division of 
 gneiss occur in Perthshire veiy remarkably, and very generally 
 m that division of it which lies between the Caledonian Canal 
 and the line which may be traced from Loch Awe along the 
 
 F 
 
6G Memoirs to H. M. Treasury respecting the 
 
 boundary of the mica slate, and the comse of the Spey. But m 
 this part also I should finally notice the very singular character 
 of that gneiss which occurs about Glenco, and * 
 
 borders^ of this mica slate: since it is not merely difficult to re- 
 
 coo'nise on the ground in its visible masses, but unites to the 
 mica slate on this^line in such a manner that it becomes utterly 
 impossible to define and separate them. 
 
 There is little to be said respecting the economical uses ot 
 gneiss • and I need not therefore do what I have just done m ffie 
 rase of granite. The granitic varieties are nearly unmpageable 
 f^any purposes of art, from the difficulty of shaping them; 
 though there are some exceptions, in which their natural stratifi- 
 cation would give two flat and parallel faces, and thus save la- 
 bour The finely schistose and laminar ones can be converted 
 into heavy slates, and are thus occasionally used m the countiy, 
 for want of a better material, or to resist high winds. But they 
 can be of no general value other than as flags ; and of these tlmie 
 is such an abundance in many more convenient rocks, that they 
 
 ffiere are many of the varieties of the schistose gneiss 
 which well deserve the attention of architects; from the tact, 
 first, of their possessing two natural parallel faces, under differen 
 deg^es of thickness, and next, from the facility with which they 
 receive the four other faces by the hammer alone. ¥ov dry, or 
 unsquared stone work, this is among the best of rocks i while a 
 very little additional labour with the pick, will also do for thein 
 what it requires much toil to perform for granite. And, m point 
 of durability, it equals the granites, while exceeding them in va- 
 riety. It will be for those interested in these arts and this com- 
 merce, to see whether those varieties of gneiss, where they he 
 commodiously for carriage, might not be rendered that object ot 
 utility which they have never yet been. ^ 
 
 Respecting the hornblende schist of Scotland, there is some- 
 what more to remark than that usual connection with gneiss re- 
 specting which geology is fully informed. 
 
 For the greater part, it occurs m beds alternating with that 
 rock, but always in a very inferior proportion ; except m the sin- 
 gle instance noticed in another of these Reports, where it forms 
 nearly the whole of the mountain Ben Lair. But I have never 
 found it as a bed among the great tracts of schistose gneiss, 
 though portions are sometimes to be observed, m ditterent con- 
 nections, which are distributed in strata and lammse, so flat and 
 so thin, that it might be used as roofing slate. As a general rule 
 however, it belongs to the granitic gneiss ; while, as tar as 1 
 have seen, it occurs only where that is a gneiss containing horn- 
 
 That it occurs also in what I have distinguished by the name 
 of the chlorite series, is a fact which will be better noticed in the 
 subsequent account of this singular collection of strata. And it 
 it is fur ther, though seldom, found as a modification of clay slate, 
 
Geological Map of Scotland. 67 
 
 the circumstance is rare, as the instances are minute : while this 
 is among those facts of a purfiy geological interest which I have 
 determined to avoid. 
 
 The unalterable nature, and consequent durability of this rock, 
 united to its convenient parallel forms, should render it a valu- 
 able material in architecture, but its colour is an objection. Its 
 exceeding toughness renders it one of the best materials for roads ; 
 but I know of no place but Ben Lair where it might be quar- 
 ried conveniently for such a purpose, and that is far too distant 
 and inconvenient a position. 
 
 I have not thought it necessary to take any notice of the varie- 
 ties of this rock ; since they are very limited, and equally well 
 known ; while, occurring indiscriminately everywhere, no geogra- 
 phical places could have been peculiarly selected for them. 
 
 The relations of octinolite schist are nearly the same; since 
 it is in gneiss chiefly that it occurs, and in a similar manner to 
 that hornblende schist from which it so slightly differs. But it 
 is so very rare in comparison, that it is very seldom found. I 
 know of its existence in gneiss, conspicuously, only in Glen Elg, 
 under a line extending to Eilan Oransa of Sky, as I have been 
 obliged to remark already. It is not unfrequent also in the west 
 of Sutherland, yet so dispersedly that it is easier overlooked 
 than found. In Perthshire it is even more rare in the same 
 connection. 
 
 If some complex hornblende schists occasionally occur in mica 
 slate and clay slate, I have seen none which approach to that 
 peculiar variety of octinolite schist which is found connected 
 with mica slate in P erthshire, and which deserves to be noticed for 
 its economical properties, though its position will probably for 
 ever preclude its use. It is the only variety which I need no- 
 tice, as it is on this account that I do notice it. It is a com- 
 pound of octinolite and compact felspar, while the separate mine- 
 rals are very distinct, and the parts large. The toughness of 
 this rock exceeds every thing that I have seen: a hammer 
 scarcely makes more impression on it than on iron. Could it be 
 transported, it would form an indestructible material for pave- 
 ments and roads ; but, lying between Comrie and Killin, it is a 
 hopeless subject for commerce or transportation. 
 
 Lastly, as connected with gneiss, I must here notice once more 
 that compact felspar, before unknown, which I have erected into 
 a rock species. I elsewhere mentioned that it could not be intro- 
 duced into the Map : but in addition to its place in Iona, there 
 noticed, I must here say that the chief other places in which 
 I have found it are. North Uist, with some of the adjoining 
 islands. Loch Maree, and Loch Greinord, while it is not uncom- 
 mon in the interval between those two points. In each of these 
 situations the gneiss itself contains compact instead of common 
 felspar. Its extraordinary toughness would render it valuable 
 for the same purposes as the compound just noticed, could it be 
 conveniently procured and transported. 
 
 F 2 
 
(>8 Memoirs to H. M. Treasury respecting the 
 
 I may proceed to the mica slate : since, whatever irregularities 
 there may be in its relations as to the order of succession in the 
 primary strata, it is at least the most extensive rock in Scotland 
 among those which might have contested for the priority of suc- 
 cession to gneiss. 
 
 Its colouring on the Map is so strongly marked, and the 
 spaces which it occupies are for the most part so extensive, that 
 very little attention is required to discern it on this work, wher- 
 ever it exists. But that great tract of it which immediately fol- 
 lows the slate belt of Arran and Stonehaven, in proceeding north- 
 ward, is the most conspicuous. In geological order, this portion 
 is the next inferior rock to the slate : in other places the rela- 
 tions are often different ; but he who consults the Map, and can 
 at the same time examine the ground, will not require a state- 
 ment of those in this place. It is to be regretted that the limits 
 to which the publication of this Map seems to be limited did not 
 admit of a corresponding and adequate set of sections, since 
 there might then have been expressed in a small space, what 
 even a volume of words could scarcely tell, and would not, even 
 then, render tangible. 
 
 It might be expected, after what I have already said on this 
 subject, that the positions of the strata of the mica slate in this 
 great tract, nearest adjoining to the secondary territory of Scot- 
 land, was steady. And this is true, both as regards the direction 
 and the dips. It is at least as true as it could well be under the 
 accidents or influences to which it has been subjected. The 
 general rule, both as to direction and dip, is infinitely predomi- 
 nant ; and I will here notice only the principal deviations, since 
 my necessary limitations exclude that minute account, which 
 would occupy a great space, and, even then, conveying no infor- 
 mation to add to the general facts of geology, would include none 
 for any useful purpose. 
 
 Beginning at the westernmost part of this great tract, the circum- 
 stance chiefly remarkable is, that the strata are very frequently 
 reversed in the peninsula of Cantyre, so as to present opposed 
 dips on each side of a perpendicular. In Arran, the effect of the 
 intruding granite has been, not only to destroy all regularity of 
 position, but to apparently transpose the order of this rock and 
 the clay slate, as traced from the eastward. 
 
 Near Loch Tarbet, and on the southern shore of Loch Fine, 
 as also in some other parts visible on the Map, it passes into the 
 chlorite series laterally, and here its positions become irregular, 
 as those of this particular series are the most irregular and com- 
 plicated that occur any where, not excepting even those of the 
 gneiss, as already noted, in certain places. From Loch Gilp 
 northwards, to its boundary at the trap of Mid Lorn, it passes 
 into the chlorite series longitudinally, as regards its own posi- 
 tion, whatever may be the case as to the utterly unintelligible 
 disposition of this series in those parts: while I confess my ina- 
 bility to trace this connection in the interior country, so seldom 
 
Geological Map of Scotland. 69 
 
 are the rocks visible, from the flatness and incumbrances of this 
 country, and so utterly does the anomalous nature of the chlorite 
 senes prevent all inferences respecting that which, if it is not a 
 solitary case, has never yet been noticed by geologists any where 
 else. That the Map must on this point be therefore uncertain, 
 and very probably defective, I cannot doubt : but I also doubt very 
 much that it will ever receive more than partial corrections. If 
 it might have been improved by a more minute research, this 
 demanded a time which I had not to bestow on such a narrow 
 tract and subject. 
 
 I need not here do more than merely notice the disturbances 
 produced on the tract of mica slate in this quarter, by the por- 
 phyry on the south side of Loch Awe, and by the trap to the 
 nc^rth of this lake. Geologists know that they ought to exist ; 
 and the details would be equally minute, useless, and inadmis- 
 sible in this sketch. 
 
 On the northern boundary, confining this to the line from the 
 River Awe to Loch Tumel, the positions and dips are not defi- 
 cient in regularity, if I except the skirts of the Cruachan granite : 
 but it is here that there occurs that wide alternation and inter- 
 mixture, already slightly noticed in speaking of the gneiss, 
 between a mica slate of the most irregular composition and 
 structure, a quartz rock often equally anomalous, an ordinary 
 schistose gneiss, and a gneiss which can often be scarcely refer- 
 red to that rock or to any other, which render the just mapping 
 of this tract as impossible as it is to ascertain in nature the 
 places, extents, and transitions of these troublesome rocks. 
 
 Quitting this line, geologists would expect to find that the 
 usual regular positions of this mica slate are disarranged in tlie 
 vicinity of the granite which occurs near Comrie : but if this is 
 the fact, the details would be as purposeless as the general result 
 of these approximations is familiar. 
 
 There is nothing to remark on the southern boundary of this 
 tract of mica slate, hence even to Stonehaven, except the gradual 
 extenuation of its breadth, since it every where maintains a very 
 consistent regularity to the eastern sea. But the northern boun- 
 dary is a much more complicated subject, as it is far from being 
 a very intelligible one. In general, the difficulty consists in that 
 change of the rocks in a longitudinal direction, which I have 
 already pointed out in some places in speaking of the gneiss. 
 This is most remarkable in the tract which extends from Ben y 
 Gloe to Mar, and towards Clova: in some parts of which, quartz 
 rock adds to the general difficulty and confusion ; as it is still 
 more increased by those frequent alternations of these different 
 rocks which aid in rendering an exact knowledge of the spaces 
 occupied by them unattainable, and an accurate record of them 
 impossible. Henceforward indeed, north-eastward, as far as the 
 granite boundary, the joint limits of the gneiss and mica slate 
 cannot be defined. There is the same kind of wide territorial 
 gradation as occurs towards Rannoch and Loch Awe ; and as 
 
 F 3 
 
70 Memoirs to H. M. Treasury respecting the 
 
 nothing but an occasional sight of the rocks can be obtained, it 
 can never be ascertained whether the visible fragment of gneiss 
 or of mica slate must be taken as indicating the establishment of 
 the one or the other rock, or whether it is not, in either case, a 
 casual bed of the one included in a real tract of the other. This 
 indeed is among the things which no examination will ever ascer- 
 tain, occur where they may : as it is likely that different observers 
 will^ give different reports and delineations, since every one will 
 natumlly be guided by the particular facts with which he has 
 
 chanced to meet. . 
 
 The next most important tract of mica slate is that which 
 reaches from Appin to Loch Ness, including Ben Nevis. In 
 general, the positions of these strata are very consistent, both in 
 direction and dip, though it is usual to find the angles highei, 
 as the dips are also frequently opposed to the more usual one. 
 But, excluding the influence of granite, as in the case of gneiss, 
 the most remarkable fact prevailing here is that change of this 
 rock to gneiss, in a longitudinal direction, which 1 already noted in 
 speaking of that substance : and adding to this, the lateral alter- 
 nations, occurring most remarkably on a broad and prolonged 
 belt to the eastward of Ben Nevis, between the same rocks, a 
 precise investigation, with a delineation equally accurate, becomes 
 as impossible as in the tracts already named. But in no case is 
 this of any moment, in any sense. To geology indeed it furnishes 
 a fact, rather than proves an inaccuracy ; teaching it that its 
 definite divisions of rocks are speculations of the cabinet, not the 
 truths of nature on the great scale, and that to define what she 
 has not separated, is to construct systems, not to record facts. 
 In every other view it is quite indifferent. If the different rocks 
 could ever be rendered of use, they are equal in point of utility : 
 and if they are looked on as the possible repositories of mines, 
 each is the same in this respect : of which indeed there is here 
 proof, in the fact that the lead and zinc of Tyndrum occur in one 
 of these undefinable places, and, specially, in an intermixture of 
 mica slate and quartz rock. 
 
 And on this subject, as concerning the statistical uses of this 
 Map, I may make this general remark. The constructors of 
 geological hypotheses, extending rules derived from a narrow ter- 
 ritory, to the whole world, have named certain rocks as produc- 
 tive of metals, and others as never containing them ; as they 
 have also undertaken to point out some necessary connexions 
 between certain rocks and certain metals ; with more that I need 
 not here notice. I have demonstrated the utter falsity of all this 
 in other well-known writings on geology, and it is therefore suffi- 
 cient to repeat it here : suffice it, that no one knows where to 
 seek for metals, or for any specific metals: wherever one is 
 found, that is a metalliferous rock ; and should it be lead, or 
 copper, or whatever else, it is a fact, and nothing more. 
 the remainder of this rock I may refer to the Map ; and it is 
 quite unnecessary to enter here on any detail of the varieties of 
 
Geological Map of Scotland, 71 
 
 mica slate, as I purposely omit all those minute and peculiar 
 facts which concern the philosophy of geology. While these varie- 
 ties are described in my book on rocks, it would be purposeless, 
 were it even possible, to state where they occur, numerous as 
 are the varieties which are found in any given spot. For geology, 
 it will be, generally, sufficient to state, that on the large scale, 
 its leading varieties are regulated by the nature of the rocks 
 with which it is associated ; so that all will know where to expect 
 its approximations to gneiss, to quartz rock, and to clay slate. 
 
 For the sake of the arts this is even less necessary, since its 
 uses are very limited. It can sometimes furnish heavy and bad 
 slates, as gneiss does ; while they are of equally little value and 
 of narrow application. It is indeed a very indestructible rock for 
 the most part, as far as the action of the weather is considered, 
 as it can bear any weight on its flat surfaces. But it cannot be 
 squared by the hammer, even to the accuracy which gneiss 
 admits, and still less can it be wrought by the chisel or pick. 
 Thence is its use confined to rude or dry stone work, as it is also 
 one of the worst materials for roads. It will immediately be 
 seen, that if there be an exception in certain cases to this asser- 
 tion, it is because there are some undefinable varieties in this 
 rock, which seem equally entitled to rank with talc slate, and 
 which I shall notice in speaking of that rock. 
 
 I have said elsewhere that I had made no attempt to represent 
 the chlorite slate of Scotland on this Map, further than as it is 
 included in what I call the chlorite series, under a general hiero- 
 glyphic ; as the reasons were shown to be valid. But I must 
 now give some account of it as it does exist. 
 
 In many places, far too numerous to name, and too minute to 
 find if they were named, chlorite slate occurs among mica slate, 
 as a transition or an incidental substance. Thus also does it 
 occur in gneiss, even insomuch that there is a variety of gneiss 
 which is characterized by interlaminations of this substance. I 
 may point out the extremity of Sleat in Sky as the most con- 
 venient place for seeing these circumstances. And thus also 
 does it form some of the thin strata occasionally mixed with clay 
 slate in a very few places. 
 
 But if, when occurring in mica slate, its strata are of very un- 
 equal thickness and extent, and sometimes not unimportant in 
 quantity, as in Cantyre and other parts of Argyleshire, though 
 incapable of being represented on the Map, it is only on the line 
 of Ben Lawers, including that hill, that I have found it occupying 
 so large a space as to be deserving a distinct colour, could I have 
 found one capable of representing it without the chance of mis- 
 take or confusion. But if it is thence necessary, as it is sufiicient, 
 thus to point it out, so is there very little to remark respecting it. 
 
 The courses and angles of the strata correspond with those of 
 the accompanying mica slate, and it passes into that rock, lon- 
 gitudinally as well as laterally, through endless undefinable 
 
 F 4 
 
72 Memoirs to H. M. Treasury respecting the 
 
 transitions. Any attempt at a distinct representation must there- 
 fore, in a rigid sense, have been inaccurate or false. And of this 
 mass I need only further remark, that it presents little variety 
 compared to those which occur in the clay slate or the chlorite 
 series, while the beds are also very generally curved or irregular, 
 and the stone itself of no use. 
 
 As I must shortly speak of the chlorite slate which occurs 
 among the clay slate of the remarkable belt already pointed out, 
 it is sufficient that I simply notice the fact here. 
 
 The Map points out the places of the chlorite series, as well as 
 it was possible to ascertain its boundaries : and if I have already 
 shown where that difficulty lies, the obscurity of the connection 
 between the mica slate and this collection of rocks will be still 
 more striking when I have described the positions of these strata. 
 
 On the margins of the mica slate at these places, taken in la- 
 teral order, there is a gradual transition effected by the intermix- 
 ture of that rock with the beds of the more perfect chlorate series ; 
 and here the usual regularity of the stratification is preserved. 
 But very shortly this disappears ; when there commences a dis- 
 order which continues throughout the whole range of the appa- 
 rent breadth of this series, estimating that from the boundaries 
 of the slate on each hand. The strata become thin and flat, as 
 the rocks are changed at every few feet or yards ; while they 
 assume every possible position, from the horizontal to the perpen- 
 dicular. Thus all inferences as to direction become impossible ; 
 or rather, there can be no such thing. 
 
 Thence, as I formerly noticed, it becomes impossible to conjec- 
 ture what are the connections between this series and the mica 
 slate, on that which is the longitudinal direction of the latter. The 
 ground renders these invisible : there is mica slate at one place, 
 and the chlorite series at another : but while the interval cannot 
 be traced, so does this breach of all the usual rules of stratifica- 
 tion prevent the usual inferences from being made. 
 
 I have however given so full an account of the positions of the 
 rocks of this series, in my work on the Western Islands, that I 
 need not dwell on them further here. In the same work I have 
 also described minutely all these rocks ; so as to supersede the 
 necessity of such a detail in this place. It must suffice to say, 
 that the leading ones are varieties of hornblende schist and chlo- 
 rite schist, and that from these, this deposit derives its peculiar 
 characters . 
 
 In this series alone, as far as I have seen, the chlorite schist is 
 so flat and slaty as to be applicable to roofing, nearly as well as 
 clay slate ; and there are quarries for country uses at Loch Killis- 
 port and elsewhere ; but they are not likely to be made subjects 
 
 of commerce. . 
 
 I formerly noticed that talc slate was so rare, and in such mi- 
 nute quantities, that it could not be expressed on the Map. It is 
 found in Shetland, in Loch Hourn, in Scalpa, and in many other 
 
Geological Map of Scotland. 73 
 
 places which I need not here name, since they are those at which 
 serpentine occurs among beds of gneiss or mica slate : and the 
 one will here be a guide to the other. 
 
 But there is an anomalous rock, more fitly referable to this 
 than to any other, though it is a transition from mica slate, which 
 1 must distinguish on account of its economical uses. It occurs 
 at fet. Cath^enne’s near Loch Fine, and in the hills south of 
 Kenmore, if under some differences ; and it has been used for 
 building the castles of Inverary and Taymouth. It deserves at- 
 tention as a building stone, from its indestructibility, and from 
 the facility with which it is wrought, even by an adze or a 
 saw. If not yet exhausted at St. Catherine’s, it might there at 
 least become an object of commerce. 
 
 If quartz rock is not unfrequent in Scotland, it occurs for the 
 most part in such small portions that I can point out but two con- 
 spicuous and continuous tracts of it ; as the Map will show where 
 they all exist. The most continuous of these forms the princinal 
 part of the chain of Isla and Jura; and the other extends, if in- 
 terruptedly, between Loch Eribol and Loch Assynt. 
 
 In every case of the occurrence of this rock, it is the most 
 distinctly and regularly stratified of all the primary strata, as it 
 IS also free of curvatures and marked disturbances : but havine: 
 never been noticed by geologists till I discovered and described 
 It m Scotland, as a pnncipal rock in the system, its history is as 
 yet limited to that which it there displays, or to the account of 
 it in my own writings. 
 
 In the chain of isla and Jura, and in the latter island most 
 clearly, its strata dip eastward, at an angle of about twenty-five 
 degrees, conformably to the other directions and dips on this 
 side and place in Scotland. In Sutherland its dips are those 
 already mentioned in speaking of the gneiss in that tract ; and 
 everywhere else, they must be determined in the same manner. 
 
 1 need not here speak of its alternations with gneiss and mica 
 slate, since it would be but to repeat what was said before : but 
 m the chain of Jura, clay slate is also found in alternation with 
 it, as 1 have represented a continuous belt of this on the eastern 
 margin of all those islands, and elsewhere in Isla. And I need 
 only further remark, that wherever, on the Map, it changes to 
 another rock on the line of its stratification, this is probably the 
 most frequent result of a disappearance similar to what occurs 
 every where in narrow collections of strata, though the given 
 record has probably also sometimes resulted from the impossibi- 
 lity of getting access to the prolongations, over flat tracts of en- 
 cumbered ground. If it therefore often appears to occupy the 
 pmmits of hills exclusively, the cause must probably be sought 
 in this, as it never fails to be conspicuous in those places. 
 
 I have so often spoken of the irregular positions of all the 
 strata in the eastern division of Aberdeenshire, that there can be 
 no surprise at seeing its distribution in this tract of country ; and 
 if 1 did not make the same remarks on the mica slate of the same 
 
74 Memoirs to H. M. Treasury respecting the 
 
 district, in speaking of that rock, the facts and the reasons are 
 
 the same. . . i u 
 
 If, occasionally, it is of a lead blue colour, it is white in by 
 far the greater part of Scotland, though coloured beds or portions 
 occasionally occur. I have, however, sufficiently described its 
 varieties in the works already mentioned, so as to render it unne- 
 cessary to do that here. But I must add, that I consider it 
 among the best of building stones, though neglected by archi- 
 tects, for the simple reason that it has hitherto been unknown. 
 
 It is a much stronger rock than even granite ; and, for the most 
 part, so hard, that even the ordinary friction in the beds of rivers 
 scarcely affects it, as the weather has no action whatever upon 
 it. It is thus peculiarly adapted for the piers of bridges, or for 
 wharfs. It is equally indestructible by fire, thus pointing out 
 other uses. In very many places, moreover, while the beds are 
 thin and regular, it possesses two parallel faces, so as to save 
 that labour which even the sandstones require; as, in some 
 places, the rock itself is the finest and most beautiful of sand- 
 stones, and workable either by the chisel or the pick. But very 
 many strata also break out with faces perpendicular to the plane, 
 as they can further be often sufficiently squared by the hammer ; 
 so that it would not be difficult to find beds applicable to the 
 most accurate masonry, with a tenth part of the labour which 
 must be bestowed on granite or sandstone. That a rock of puie 
 white, often emulating white marble in its colour and surface, 
 must be a beautiful building stone, I need not say. 
 
 It will be for architects to inquire respecting this, as it will be 
 for Scotch commerce to ascertain whether the uses in question 
 can be expected from this rock for extended purposes; and 
 should it prove so, I may point out J ura as the place where it 
 can most easily be quarried and shined for an English market, 
 though fully as accessible at Loch Eribol, and also near Loch 
 Leven and elsewhere on that western shore, where theie occui 
 those small beds which I’equired no particular description, while 
 their indications can be seen in the Map. 
 
 The clay slate of Scotland occurs in a more dispersed and 
 remarkable manner than either the gneiss or the mica slate : and 
 it will not be difficult to see its larger tracts on the Map, though 
 the minuter ones will require an accurate inspection, as there are 
 some, such as that near Loch Eribol, and tliat which accompa- 
 nies the serpentine of Portsoy, which I have scarcely succeeded 
 in rendering visible, as there were many similar ones which I was 
 obliged to omit under the same difficulties. 
 
 The principal tract of this rock is that which forms the pri- 
 mary territory of the south of Scotland, unaccompanied by any 
 other primary stratum. Taking it as an entire mass, it resembles 
 very much the similar tracts in Cumberland, the Isle of Man, 
 Wales, and Cornwall with Devonshire: and it is visible that it 
 follows granite without the intervention of any other strata. 
 
 It is evident that the general bearing of this great mass corres- 
 
Geological Map of Scotland. 75 
 
 ponds with that of the primary strata of Scotland in general. 
 JBut it is by no means easy to trace the individual directions of 
 the strata, as there is a similar difficulty respecting their dips : 
 these things arising, partly from the encumbered state of the 
 ground and the small quantities of rock generally visible, but 
 partly also from the nature of this slate, and evidently, at times, 
 from actual disturbances of the general direction and dip ; most 
 of which occur near the granites and the porphyries, as might be 
 expected, though some seem to be quite independent of such 
 a cause. 
 
 It would be a vain and purposeless attempt to describe these 
 vacillations of position, otherwise than as 1 may here point out 
 the great and extensive irregularities in the neighbourhood of the 
 great granite tracts of Criffel and Caimsmuir. And it must 
 suffice to say, that barring those and others, and however appa- 
 rently irregular the positions may seem on a superficial view, or 
 by carelessly confounding the fissile tendency with the planes of 
 stratification, as is very commonly done, the great average direc- 
 tion is to the north-east, as the dip is to the south-east, under 
 various but generally high angles ; while in the districts about 
 Hawick, and in many more, this fact is extensively visible. 
 And where there are tracts of strata that interrupt the longitudi- 
 nal continuity of this rock, as near Moffat and Sanquhar, these 
 are plainly portions of the superior secondary strata which other- 
 wise skirt it for the most part. 
 
 The general average character of this slate is considerably 
 different from that which prevails in the narrow belt which skirts 
 the Highlands, and in that of Aberdeenshire, those being the 
 only two other tracts of noted extent. I have never found in it 
 other rocks than fine slate and that coarse kind, under endless 
 varieties, which has been termed graywacke, if I except the sili- 
 ceous schists. But the coarser kinds are infinitely predominant, 
 as the fine ones generally form but thin and casual beds in them. 
 Still more rarely does it produce fissile slate, either for flags or 
 roofing : while the few quarries wrought, near Peebles for exam- 
 ple, near Loch Ken, and in a very few other places, are not situated 
 so as to be the objects of a distant commerce. What future re- 
 searches may affect over so vast an extent, and where so much 
 of this slate bounds with the sea, it is impossible to foretel : but 
 under all the views which a geologist can take, it would I think 
 be decided that useful slate will probably prove rare in this great 
 tract, and that the discovery of it is likely to be the result of 
 chance far more than in the other slate districts of Scotland. 
 
 The next great tract of this rock requiring notice is that sin- 
 gular belt which so well marks the general direction of the pri- 
 mary strata of Scotland. This is perfectly definable on its south- 
 eastern margin, as might be expected, but not always so well 
 marked on the other boundary. It is not only that great tracts 
 of peat and soil prevent it from being visible, very often for many 
 miles, and most remarkably from Dunkeld eastward, even to the 
 
M}^ 
 
 76 Memoirs to IL M. Treasury respecting the 
 
 sea, but that it demonstrably passes into the mica slate, often 
 after a very considerable extent of intermixture, by a gradation 
 of alternations. If in some places, therefore, the north-western 
 boundary is sufficiently accurate, this is not always the case, 
 especially to the eastward. How it is extenuated near the granite 
 of Comrie, and near its eastern termination, how it skirts the 
 northern shores of the Clyde, intersects Bute, and is stopped by 
 the Arran granite, the Map will show. 
 
 This latter is the only place where its regular positions are re- 
 markably disturbed, if I except the neighbourhood of Ben na 
 Cherry and Loch Turrib, at both of which places this was to be 
 expected. Every where else, while it is evident that the direc- 
 tion of the strata must be regular, so are their dips south-easterly, 
 though under diverse, if generally high angles : although there are 
 places affected by trap in the same manner as by the granites, 
 and although in some others it is easy to mistake the planes of 
 the fissility for those of the stratification. 
 
 Though this belt is laid down as if it were all slate, that is not 
 always the fact, however impossible it was to note it otherwise on 
 the Map, as any one can see in examining its structure. It must 
 suffice that the far greater part of the whole breadth consists of 
 slate ; and, very predominantly, of the finer kind. The coarser, or 
 the graywackes, generally occur with the other, often anomalous 
 rocks, that are interstratified with it ; as the whole of these also 
 generally occupy a single portion of the belt. These comprise 
 varieties of chlorite schist chiefly, but often of a very singular 
 structure, with rocks that might perhaps be referred to some of 
 the varieties of gneiss, and with mica slates ; but I need not here 
 enter on these details. They are fully given by myself in the 
 account of the Western Isles, and there is also a coloured section 
 by General Imrie, which gives them with great precision in For- 
 farshire ; being the only accurate draught of any portion of its 
 geology which Scotland has hitherto produced. These works 
 may be consulted : but if any one desires to see the rocks them- 
 selves, I know not where he can more conveniently trace the 
 whole than near Loch Cateran. 
 
 Slate of the best quality might doubtless be found almost every 
 where along this long line : and the present accurate indication 
 of its place and extent, hitherto unknown to Scotland, will pro- 
 bably prove among the most valuable of the economical applica- 
 tions of this Map and Survey, since a great deal of expense is 
 now wasted on a land-carriage which might thus be superseded. 
 If I have thus further discovered fissile and useful slate in many 
 places hitherto unremarked, I know not but that the enumeration 
 would involve nearly the whole line, at least on its southern margin, 
 since it is there chiefly that the useful slate occurs : while I need 
 not do this, when so many other circumstances must unite to 
 render a slate quarry an eligible undertaking. Nor need I per- 
 haps do more than name a few places where slate is now wrought 
 upon this line, since these are things of general notoriety. Among 
 
Geological Map of Scotland. 77 
 
 these are Arran, Bute, Luss, Benvorlich and Dunkeld, with other 
 places, connected or intermediate. 
 
 The slate of Aberdeenshire is seen to possess that irregular 
 extent on the Map which marks all the stratified rocks in this 
 quarter. Its internal disposition is however sufficiently regular: 
 while I do not think it necessary to enter on details that would 
 only involve repetitions. That it produces workable slate at Ford- 
 law is well known, as it would assuredly afford it in numerous 
 other places. The assignment of its boundary and place on the 
 Map will therefore similarly lead to profitable knowledge in this 
 populous country. 
 
 I need not here separate the deposits of slate which are marked 
 on the Map in Isla, Jura, &c., and in the isles where that sub- 
 stance is so well known by the extensive commerce in slates 
 which they carry on. In a geological view all these are analo- 
 gous to those which can be traced on the Map in Knapdale, 
 Appin, and other places, being portions, more or less wide, of 
 collected strata alternating with the neighbouring mica slate and 
 quartz rock. And thus may their dips be inferred, as their 
 directions are visible. With respect to their economical value 
 and produce, the quarries of Bdlahulish are as well known as 
 those of Seil and Lunga : and there is no doubt that many more 
 might be wrought in all these places and islands, were there any 
 commercial expediency in competing with those which have so 
 long possessed the market. 
 
 In Isla alone I desire to point out the valuable flags and 
 beams \yhich are furnished by the western portion of the slate, 
 and which have hitherto been little attended to, otherwise than 
 as the common people sometimes use the flags as walls for their 
 smaller buildings. The beams are so long, and so well shaped, 
 that they might even now be used as such for houses ; as it is 
 also not difficult to trim the less regular ones to a true shape by 
 the adze alone. Architects may inquire what their value would 
 be, as compared to iron, for fire-proof apartments. 
 
 If I have mentioned the slate strata which occur in gneiss, 
 indicating on the Map those about Loch Maddy, and here naming 
 those, less visible on it, about Loch Eribol, they are little more 
 than geological facts to which geology may attach such value as 
 it deems proper. I have not been able to find, in any place, that 
 the slate thus associated will produce roofing slates. 
 
 It would be here impossible to enumerate the places of the 
 primary limestones of Scotland by name, for want of references. 
 They must be sought on the Map ; where it will also require 
 care to discern some of them. If I except one tract in Isla, 
 another near Campbelltown, the island of Lismore, and that 
 which runs along Glen Tilt towards Loch Tumel, there is not 
 one spot of primary limestone of any notable extent; as even 
 these are very insignificant in dimensions, compared to the great 
 mass of the primary strata. Of all the others I may say, that 
 they are the thin edges of casual strata, and if not soon exhausted 
 
78 Memoirs to H. M. Treasury respecting the 
 
 along their directions, ceasing to be traceable, from the circum- 
 stances formerly mentioned, when I also showed how greatly 
 I was oblio"ed to exaggerate, their breadths always, and their 
 lengths very generally, that they might be at all visible on the 
 Map. 
 
 It is superfluous to say any thing respecting the dips of these 
 strata, since they are determined by those of the adjoining ones. 
 And the only question respecting their directions is, whether or 
 not they proceed much further than is now visible, and whether 
 especially those portions which are now discontinuous on the 
 Map are invisibly connected. There appears some probability of 
 this, in examining'especially those which range from Glen Tilt to 
 Loch Earn over a somewhat wide space : but it would have been 
 hazardous to have inferred what cannot be traced, when the 
 exceeding tenuity of some of these beds is recollected, and when 
 there are such incongruities among the apparent lines of direc- 
 tion of those which are here noted. What I have done, in ascer- 
 taining many before unknown, in prolonging the extent of others, 
 and in tracing the probable connections or continuity of a great 
 many, will not only lead to the more extended knowledge of this 
 rare and equally needful substance in the primary districts of 
 Scotland, but also point out to the natives where they may be 
 sought. I discovered many myself in this manner : those who 
 reside on the spots, and are also immediately interested, will 
 now be able to do this far more extensively and effectually; 
 and thus, I trust, will this portion of the Map become of an eco- 
 nomical value much greater than they who do not know the 
 wants of this country may imagine, and the impediments which 
 the want of accessible limestone in particular throws in the way 
 of the agriculture and improvement, with the further great loss 
 which occurs from the distant transportation of what might often 
 be procured near at hand. It is not easy for the peasantry to 
 find these limestones; and they do not always recognize them 
 when visible, so little do they resemble the more familiar rocks 
 of this nature. Thus it is, that great tracts of limestone remained 
 unknown near Rannoch and Blair, because these varieties have 
 the external appearance of mica slate and gneiss : and thus was 
 even the white limestone, or marble, of Glen Tilt used in build- 
 ing, under the belief of its being a sandstone. Thus also have 
 I added the whole of this extensive mass to the old resources, 
 since it had been unsuspected ; as in other places, such as near 
 Monterriarn, Cushiville, and elsewhere, I have substituted 
 quarries on the very spots where the materials were required, 
 for others many miles away, under a great expense of trans- 
 portation. 
 
 Having, in the work on rocks, described all the varieties of 
 this limestone which I knew, I need not repeat the enumeration 
 here : and shall content myself with merely noticing those which, 
 besides their usual agricultural and architectural uses, might be 
 used for ornamental marbles. Glen Tilt is the chief deposit of 
 
Geological Map of Scotland. 
 
 79 
 
 these ; but its peculiar produce is now so well known that I need 
 not describe it. The Gairloch Isles also contain ornamental 
 breccias: but of the few other ornamental primary limestones 
 that I have found or seen, there are none so conveniently situated 
 as to admit of being profitably wrought. The white marble of 
 Leadbry in Sutherland seems as scanty in quantity as it is in- 
 convenient in respect to transportation. The quarry of Three is 
 ruined : that of Iona exhausted. 
 
 In Scotland, there is no extensive tract of serpentine. All 
 those which occur are very small, and often so small that even 
 the minute spots by which they are noted on the Map are great 
 exaggerations. I must request those who may examine this 
 Map to look carefully for them, or else they may escape atten- 
 tion. If some are omitted, it is from a minuteness so extreme, 
 that I knew not how to render them visible by means of their 
 colour, strong as that is : as I have also avoided the notice of 
 others reported to me, which I could not find ; not less declining 
 to record some, from well-grounded suspicion of the reporters. 
 
 The several serpentines noted amid gneiss are interstratified 
 with it : and the same is true where it occurs with mica slate or 
 clay slate. These are accompanied by more or fewer of the 
 usual minerals : but I need not enumerate what is so well known, 
 especially since the costly minerals of Scotland, as objects of 
 mineralogy, constitute no part of these Reports. But none of 
 these are of ornamental use, except that of Portsoy: while even 
 that is not now wrought, as being an article not in demand. 
 This well-known one is associated with a veiy small body of clay 
 slate lying in gneiss : as the Map, however minute, will I trust 
 
 last circumstance deserving notice as to these serpentines 
 is, that they occur as large nodules in Aberdeenshire, connected 
 with granite alone, as if imbedded in it. 
 
 There was formerly a fact of geological interest, in a trap vein 
 passing into serpentine, at Cluny in Perthshire : but the quarry- 
 ing of the lime has destroyed the whole, so that it now is only 
 known by a former record of my own, which they who may now 
 seek for the spot in vain, might deem a fiction, if so inclined. 
 
 I showed, in another place, the difficulty which existed in 
 distinguishing the ancient porphyries from those belonging to the 
 trap rocks, and mentioned the places where I had intentionally 
 coloured as ancient those which I knew to be modem. With 
 this correction, the quantity of ancient porphyry on the Map is 
 easily found, as it is very trifling. The most extensive mass is 
 that which occurs near Loch Fine: the next, near Kirkcud- 
 bright. But neither of these possesses any geological interest 
 to demand description here ; as, in neither, did I find porphy- 
 ries so ornamental as to be subjects of economical interest. 
 
 This is however the case, 1 think, with the island Devar. 
 The green porphyries of this spot are ornamental, with the addi- 
 tional merit of novelty : the detached blocks require no quarry- 
 
 ex ' n. 
 
80 
 
 Memoirs to H. M. Treasury respecting the 
 
 ing, and would easily be wrought into slabs : and the transport- 
 ation is perfectly easy. . . j • i 
 
 The crowd of porphyry veins in Glenco and in Gruachan, 
 where there is no mass of that rock, is an object of geological 
 interest as is the fact I formerly mentioned, of the more than 
 probably recent date of those which could be otherwise judged 
 ancient. And this is all as regards these also ; unless I add to 
 this, the probability that it is through the influence of these that 
 the Vneiss of Glenco possesses so singular a character, both in dis- 
 position and texture. And here I think that there are many orna- 
 mental porphyries which might be wrought with advantage, from 
 the facility and power which the river affords ; though it must be 
 for others to see whether a taste can be introduced for such 
 a domestic manufacture, in competition with the favoured foreign 
 produce of Sweden. 
 
 On the subject of the casual rocks, jasper, chert and siliceous 
 schist, whether occurring among the primary or the secondary 
 strata, I need add nothing to what I said in another Report ; 
 since I am not here to discuss nice questions of philosophical 
 geology, especially as I have elsewhere fully described rocks 
 which had been always neglected or misunderstood, and which I 
 have added to the ancient imperfect system of geologists. The 
 jasper of the Burn alone, I have already said, might possibly 
 prove an object of economical speculation or use. 
 
 I have taken no notice on the Map, of what I, and some 
 foreign observers, have thought to be a primary red sandstone. 
 What I know and conjecture about it, I have stated in my system 
 Qp geology and elsewhere i and for the present it stands among" 
 the quartz rocks : since it will require much more investigation 
 to know whether it deserves a distinct place. ^ At any rate, it 
 was a circumstance of no moment as to the leading object of this 
 Map and its appended Reports. 
 
 I must proceed to the secondary strata and rocks of Scotland, 
 as, of the former, I have already given a general sketch indica- 
 tive of their number and limitations. 
 
 The red sandstone is the first of these. For the greater part, 
 its extent and places, however remote and scattered, are suffici- 
 ently obvious on the Map. Yet not so universally but that I 
 must direct the attention to some of these, since there is an in- 
 terest attached to those fragments which does not exist respecting 
 similar ones in the primary strata. Both on the sea shores and in 
 the interior country, they mark a wasting of the surface which 
 is an object of geological interest, though it should possess no 
 other. But I must first note the principal masses, as the frag- 
 ments in question must be referred to those : as it will also be the 
 clearest method to describe the characters of each division sepa- 
 rately ; since the differences, in different parts of Scotland, are 
 very considerable. 
 
 I may take all of those sandstones which are found to the 
 southward of the north-western boundary of the southern slate as 
 
Geological Map of Scotland. 8i 
 
 one, since there is tolerable evidence of some former connection 
 more general. 
 
 The most continuously extended tract is that of Berwick and 
 Roxburghshires. That of the valley of the Nith may be taken as 
 one, though it is interrupted by a mass of slate, and it is conti- 
 nuously connected eastward with that which skirts the English 
 border. The detached portions of this are so scattered, that it is 
 needful to point them out here : especially as some of those noted 
 in the Map, would, in nature, escape all but a very minute and 
 discerning observer. 
 
 Westward, the most remarkable among these, is that narrow 
 line which extends between the mouth of the Urr and Kirkctid- 
 bright : nor would it easily be recognised as such on the Map, 
 but for this note : Applegarth and Moffat serve to mark two 
 other detached portions, but much more conspicuous ones. But 
 there are tw'o spots on the Map near the former, and one between 
 Tinwald and the latter, which will not easily be perceived on 
 the ground, since they do not exceed a few yards in dimension ; 
 as the former presents nothing but the shale of this series : and 
 they are noted on the Map for the purpose of showing that the 
 extent of this sandstone was once much greater than it is now. 
 They will also serve to show, as I elsewhere remarked of the 
 slate about Loch Maddy in North Uist, the care with which this 
 survey was carried on ; since, in the case of this tract of slate in 
 particular, the continued extent of the same rock which occurs 
 without any variations, offers a strong temptation to follow the 
 usual practice of geologists, and to lay down whole tracts by 
 mere conjecture. 
 
 The portions of this sandstone on the skirts of the slate near 
 Southerness, and all those which extend on the eastern side of 
 the Nith in a similar position, as far as the Carter-fell, may be 
 looked on in the same point of view. They are that portion of 
 this rock which, following the slate, are covered by the coal se- 
 ries, and they are visible or not, according to the presence of this 
 and the nature of the ground. Thus do they also here appear as 
 if in the middle of the coal series, these being the places where 
 that covering is absent. I elsewhere noted the impossibility of 
 tracing every point of that which must contain the common belt 
 including the boundary line of the slate and that of the red sand- 
 stone towards the coal series. There may therefore be deficien- 
 cies in the mapping of these few portions ; which future obser- 
 vers may supply if they think fit to pursue that subject, so little 
 important, on which I had no time to bestow. He on whom it 
 fell to traverse every mile of all Scotland, and all its hundreds 
 of islands, had other work to do than to spend days on so narrow 
 a spot and so paltry a subject as this. If, lastly, I notice the 
 fragments of red sandstone about Trendergarth. it is evident that 
 these are the result of the intrusion of trap into this border. 
 
 The very minute fragment of this rock near Boonhill in Ber- 
 wickshire was laid down for the same reason as those near Mol- 
 
 G 
 
a 2 Memoirs to H. M. Treasury respecting the 
 
 fat : as is tliat near the Aildoii hills. They are rather indica- 
 tions that the rock once extended over these parts, and are, 
 thus, simple questions of geological curiosity. It is quite pio- 
 bable that others may exist over this great tract of slate ; as 
 1 suspect they do about its westernmost extremity, in that pe- 
 ninsula which terminates in the Mull of Galloway, from the 
 frequent occurrence of heaps of the fragments of this sandstone. 
 But I did not find what 1 sought for : as, in this and similar things, 
 we must be indebted to good fortune where we cannot carry on 
 a microscopic examination of every yard of ground. 
 
 The fragments on the eastern shore of Berwick are visible 
 enough ; and, in the Map, they represent the exact sizes and 
 plac^ : if they indicate nothing more, they at least show the 
 action of the sea on this coast. 
 
 Of all this portion I may say generally, that the angles of ele- 
 vation are low, whde the variety of position is such, that all 
 attempts at describing even what can be investigated would be 
 vain. Of course, the higher angles will naturally be expected 
 near the slate, as the disturbances will be near the trap. 
 
 This southern sandstone is of an exceedingly uniform character 
 almost everywhere, both in the mass and in the details. Ihe 
 occurrence of conglomerates is rare, and there are none of those 
 conspicuous masses which occur in the northern portions of the 
 same rock. It also contains very little shale in comparison; 
 while over great tracts, not the slightest indication of this can be 
 discovered. Its limestones, as far as I know them, are noted in 
 the Map. It is almost invariably red, and is rarely a very hard 
 rock ; though I know of no spot anywhere where it is not ayery 
 good building stone; while, of practicable quarries there is no 
 end. Near lliornhill, its strata are sometimes so thin and flat 
 that it is quarried and transported for roofing. 
 
 The Map in this part will show the inhabitants how much more 
 widely they may quarry for this rock than they yet have done, 
 and thus, in many places, save much expense. And the following^ 
 remark I may here make once for all, as applying to the whole of 
 Scotland where this, and indeed every other useful rock occurs. 
 
 I am not aware that any of those jointly practical and scientific 
 persons in whom the ordinary road engineers, surveyors, and 
 coal-viewers are included, have ever extended their views to the 
 general geological structure of the country, anywhere. How far 
 the superior class of engineers has done this I do not know, 
 since they have not published their observations ; while it is not 
 improbable that their knowledge of this nature is confined to the 
 districts in which they may have been interested. The appli- 
 cable practical knowledge, as relates to quarries, therefore, lies 
 generally, with a class of people even inferior in rank to the first 
 set ; with contractors, and quarrymen and masons, and the low- 
 est rank of road inspectors. The acuteness, and the knowledge 
 of these men is indeed very remarkable, as I have often been 
 indebted to them for useful information ; but it is confined to 
 
Geological Map of Scotland, 83 
 
 their own narrow limits of observation. To them, therefore, the 
 extent of their quarry and that of the rock is very often the same ; 
 nor could I find that any of them had imagined the continuous 
 extension of such rocks, in the way that geology is enabled to 
 point it out. And it is by them that the workable rocks are as- 
 signed, as their knowledge is naturally supposed to be the true 
 point of reference. 
 
 It is from this want of geological information therefore, or of 
 what is equivalent, sufficiently extended practical knowledge, 
 that there arises the inconvenience, with necessary additional ex- 
 pense, to which I have more than once alluded, which follows 
 from an imaginary confined locality of workable rocks ; since it 
 is often plain that the persistence in working a single quarry for 
 a distant sale, does not follow from the work having been organ- 
 ized, or the market having become an usage ; while it is further 
 visible that many of those old quarries have become so deep and 
 inconvenient that they ought to be abandoned in favour of new 
 ones, and, above all, where the distance from the use of the ma- 
 terials renders the transportation expensive. The utility of this 
 Map on the subject of the red sandstone alone will thus be seen 
 to be as extensive as it is apparent ; while there can be no diffi- 
 culty, among a people like the Scotch peasantry, in extending 
 all the useful knowledge of this nature which the present Map 
 contains, by some form of publication adapted to their means. 
 It is not a work to be confined to libraries and geologists : and 
 though no cheap transcript can be very accurate, it may always 
 be rendered useful. 
 
 But before dismissing this southern portion of the red sandstone, 
 
 I must distinguish that narrow line near the Urr, already men- 
 tioned. The strata of this are so nearly horizontal that they may 
 be considered as such ; and it is a solid sandstone without shales, 
 in beds of an especially convenient thickness, and remarkably 
 free of destructive fissures, while sufficiently divided to render the 
 quarrying easy. It is also, beyond comparison, the most per- 
 fect stone of its kind that I have seen in Scotland, as a building 
 material, while its predominant colours are pale greys. In addi- 
 tion to this, it is already an open quarry of miles in leno*th, 
 skirting the sea shore to a considerable breadth, like a continuous 
 series of a gigantic pavement. It may be true, that no lighters 
 could lie near it at present, except in calm weather ; but the 
 very first working would form a dock, and that dock would cost 
 nothing, since the excavated materials would be the saleable 
 stone itself : while the flatness of the surface would form a con- 
 venient lodgment for any machinery. The engineers of the Li- 
 verpool docks have not been well advised in neglecting this rock, 
 to quarry the granite of Builth at a far greater expense; when 
 it is in every respect a superior stone, and affords blocks, almost 
 ready squared, of nearly any dimensions, peculiarly applicable 
 to works of that nature. Better known hereafter, it may become 
 
84 Memoirs to H. M. Treasury respecting the 
 
 the point of supply for uses of this kind to all the West of 
 
 England. , . i • i 
 
 1 will not quit this tract without yet pointing out the singular 
 redness of the slate about Eyemouth, in those parts whence the 
 sandstone appears to have been worn away, together with the 
 remarkable disturbances which it there exhibits. Geologists are 
 already informed of the curvatures in the slate of this coast. 
 
 I will next take as most convenient, and as if it were one 
 mass, this sandstone as it is bounded by the north-western edge 
 of the southern slate, by the Forth and Clyde Canal, and by a 
 line between Glasgow and Ayr. But I must appeal to the Map 
 for its undescribable places, as one general description must 
 suffice for the whole. 
 
 Appear in whatever manner it may at the surface, it must be 
 viewed as the basis on which this great coalfield lies ; concealed 
 by that covering in some places, and displaying itself in others. 
 That display, which interferes with the continuity of the coal 
 field, is sometimes owing to the wasting of the superior rocks, 
 at others to its undulations or elevations; while in soine cases, 
 though by no means in all, these are traceable to the influence 
 of trap. 
 
 Thus, in some cases, it occupies low tracts of land, or appears 
 in narrow lines, sometimes near the slate, as would be expected, 
 at others near the trap masses ; as, in other parts of this great 
 coalfield, it is totally invisible in both these situations, and every 
 where else ; though some of the coal workings give evidence of 
 its existence beneath. In other places, it is elevated into con- 
 siderable hills, as in Hawkshaw-hill and Cairn-table; while if 
 these display no other rock, the not less high land intervening 
 between Muirkirk and the Irvine is extensively covered with 
 
 trap. ... 
 
 It is a natural result that it must possess great irregularities 
 of position and elevation. To all this indeed there is no end. 
 Very little of it all can however be seen; and such is the uncer- 
 tainty, that not a mile can be inferred. And as ten thousand 
 sections, and a volume of description, would not include the 
 whole, even as it is assignable, while even that is but the smallest 
 portion, I need take no further notice of that which, could it 
 be all known, would scarcely be an object of either use or 
 curiosity. 
 
 Like the southern tract already described, this one contains 
 very little shale, and is very generally a red rock, not often very 
 remarkable for its hardness. x4nd, in a similar manner, it is 
 very deficient in conglomerates. Such varieties as may occur, it 
 would be here superfluous to notice; since, having elsewhere 
 described these fully, I have here chosen to limit myself to those 
 which, from their places and qualities, are, or may be, objects of 
 economy : but there is one not unfrequent fact which I inust 
 point out, because it so often interferes with the correct assign- 
 
Geological Map of Scotland, 05 
 
 merit of the boundaries of those detached pieces of this sand- 
 stone. 
 
 It is evident in the first place, that the mountain limestone is 
 often wanting between this sandstone and the coal series, and 
 next, that this series follows the inferior rock in parallel order as 
 well as in contact. It further happens that the rocks of the 
 coal series are sometimes red, as those of the red sandstone are 
 known to be occasionally white, or as it also happens, that, in 
 some places, both sets are of brown, or other colours, in com- 
 mon. Thus there are many places, where the rocks are but 
 partially visible especially, in which it is utterly impossible to 
 conjecture which is which, since there is no guide of any kind. 
 And if this is a frequent occurrence in Ayrshire, as it also ap- 
 pears to happen in the Edinburgh district, I may make the 
 remark general as far as the boundary of this great coalfield ; 
 since it is evidently the case in Fife, which I might have included 
 in this division, instead of associating its red sandstone with the 
 great belt that follows the primary rocks of the north, to the 
 southward. And to save a future examination of the same 
 question, I may here state, that this is the case especially on that 
 margin of the joint coal series and red sandstone which is 
 bounded by the northern trap of Fife eastward. Different ob- 
 servers will probably judge differently as to the definition of 
 these two rocks : in the mean time, under such a lack of evi- 
 dence, I have taken the course which seemed at least as right 
 as the other. It is not by assertions, most assuredly, and cer- 
 tainly not by those of the ignorant, superficial, vain, and arro- 
 gant intruders into this science, that the truth will be settled. 
 
 Thus further excluding Fife in this division, under a desire to 
 unite all the red sandstone of the coalfield under one discussion, 
 
 I may lastly point out two narrow lines which occur on the 
 shores at Wemyss and Anstruther, a small spot at Denino, and 
 another not far from Cleish. Whether these are the old red 
 sandstone, or red portions of the coal series, seems very difficult, 
 equally, to determine : but at any rate they are not parts of the 
 red marl series. 
 
 Tlie next portion of the red sandstone forms the most conti- 
 nuous and extended tract which Scotland presents. And I need 
 not describe what the Map displays so perfectly. I need only 
 gnide the observer’s eye to its outskirts and fragments on the 
 shores and islands of the Clyde, and on the coasts of Cantyre ; 
 as, in many cases, sections might perhaps have displayed these 
 more fully than could have been done in such a Map. It is 
 easdy seen in nature, and not less easily conjectured from the 
 Map, how much of this is owing to the waste of the surface and 
 the sea shores, and how much has arisen from the intrusion of 
 trap. 
 
 This tract is not the flat country which might be imagined 
 from the Map. The sandstone hills of the Sidlaw arc high land, 
 as IS much of Forfarshire, and it is generally a kind of mountain 
 
 a 3 
 

 i ' j i V 
 
 i 
 
 llrlil-. 
 
 86 Memoirs to H. M. Treasury respectiny the 
 
 rock on the skirts of the slate ; as the braes ot Doune and other 
 places also present hills of considerable elevation and extent. 
 An observer will find but little guide in the forms of the l^d . 
 and if, especially, he trusts to this near the primary boundaiy, 
 he will be often greatly deceived. Definite as that line really 
 is, there is not one on the Map which demands more labour. 
 
 ’ It is equally a matter of course, that the positions of the strata 
 vary over this tract; and the variations are even greater than in 
 the southern divisions of this rock. It is as impossible to describe 
 them, for the same reasons ; and it would be equally purpose- 
 less were it done. But it is a general remark, that the strata are 
 highly elevated near the primary boundary ; being in some places 
 vertical, as, in a few, they seem to have been partially reversed. 
 In the lower districts generally, they tend to a horizontal posi- 
 tion ; but to this rule also there are endless exceptions, as the 
 hilly tracts also do not always imply high elevations of their 
 component strata. Some of the Forfarshire hills are foimed 
 from strata at no high angles : and at the low tract near Dun- 
 riotter, where the flatness of the surface would also lead to the 
 expectation of low angles, the strata are vertical. This must 
 suffice as to positions, in this great tract : local details must be 
 entrusted, with the rest, to far other works than such a Memoir 
 as this : as they may hereafter constitute the high fame of some 
 aspirant who will appear to have discovered vast things. 
 
 This tract of standstones presents far more variety of mineral 
 character than the preceding ones. There is scarcely an excep- 
 tion to the rule that the boundary with the primary rocks is a 
 cono’lomerate ; of great variety of character, and often of great 
 extent also. But such conglomerates occur in many other 
 places, often far remote from the primary rocks : and there is no 
 more striking instance of this, than at Dunnotter, just noticed. 
 
 In the western division, this rock is so very generally simila 
 to those already described, that the exceptions need not be no- 
 ticed. It is generally red, not often very hard, and contains but 
 little shale. 'Towards the middle, grey and whitish beds are not 
 uncommon: and while some of these have been quarried for 
 building, there are much wider resources of the same nature. 
 In the more eastern portions, comprising Forfarshire, though the 
 predominant quantity is also red and free of shales, there are 
 extensive tracts of a pale grey, or whitish, as there are also con- 
 siderable ones abounding in blueish or grey shales. Near For- 
 far, Carmyllie and Panmure, the intermixture of these shales 
 with flaggy varieties of this sandstone, has led to the working of 
 extensive quarries; as such might be opened in many other 
 places were it necessary : and as there is scarcely a spot oyer 
 this great extent which would not afford sandstone quarries. 
 The remarks formerly made on this subject are equally applicable 
 Ii6r0. 
 
 The detached fragments on the shores of Seil, Kerrera, Oban, 
 and Upper Lorn, with that near the bridge of Awe, were formerly 
 
 D 
 
87 
 
 Geological Map of Scotland. 
 
 pointed out, lest they should escape the eye. They cannot be 
 referred to any other mass : and the conclusions in geology to 
 which they lead are the same as those which arise from a con- 
 templation of the scattered lias of this coast. They have little or 
 no economical interest. 
 
 I shall simply point out the patch at Kildrummie, of which 
 the insulation is remarkable, and that which extends from Troup- 
 head to Fyvie, with its accompanying fragments. These last at 
 least, with the similar extenuated portions to the north, mark 
 a once greater extent of this rock : though whether any one will 
 be bold enough to infer the former connexion of the two, is what 
 I do not know. Except that the portion of this rock at Kil- 
 drummie affords white sandstone, and is quarried, and that the 
 other is a red rock most generally, similar to that of the south, 
 I know not that these tracts admit of any remarks that are worth 
 repeating : unless I note the conglomerate near Troup-head which 
 is wrought for millstones. 
 
 I may take the great and scattered tract which commences 
 near Speymouth, extends to Loch Lochy, and then proceeds 
 north to Reay, under one view, reserving Caithness, as marked 
 by some peculiarities. It is all sufficiently visible, except a small 
 point near Cullen, which any one who chooses thus to speculate 
 may use for connecting this tract with the one near Troup-head 
 in former times. And if I add to this the independent spots at 
 Ben Griam, the mouth of the Hallodale, and Tongue, they will 
 equally serve to establish a speculative connexion between the 
 eastern and western sandstones in this division of Scotland. 
 
 Though taken as one mass, under every appearance of a for- 
 mer more intimate connexion, the differences of character, both 
 on the great and small scale, in different parts of this tract, are 
 considerable. But as a geological treatise would be required to 
 describe all this, I must confine myself to some of the most 
 striking facts. 
 
 From the Spey to the Moray Frith, excepting on the primary 
 boundaries, where the usual variety of conglomerates occurs, the 
 general character is in all respects similar to those of the south 
 of Scotland, and of the western portions of the great middle 
 belt. These I need not repeat. And the same holds generally 
 true of the great tract reaching from the Moray Frith to the Ord 
 of Caithness. In a former place I pointed out the peculiarities 
 of some of these junctions : but on these and the circumstances 
 of the conglomerates which attend them, it is not my intention 
 here to speak, as being questions of geological philosophy. 
 I need only add respecting the conglomerates in this division, 
 that they are often remarkable for their extent and general cha- 
 racters, especially in the great valley of Glen More, and its con- 
 nexions. 
 
 Taking Caithness as somewhat separate, though still connected 
 with the former by means of the insulated fragments j ust noticed, 
 the character of its sandstone is so very difierent from what the 
 
 G 4 
 
88 
 
 Memoirs to H, M. Treasury respecting the 
 
 same rock displays everywhere else, that it demands a new no- 
 tice. It is almost everywhere so flat that it is best referred to the 
 horizontal position as a general rule. The Map will also show 
 the great quantity of shale which is present, as of the nature of 
 this entry I formerly spoke. And in some places, as is visible 
 both in nature and on the Map, the extent and depth of the un- 
 mixed shale is such that it seems to claim a place as a distinct 
 rock. 
 
 This shale is always dark, and often black, though the sand- 
 stone should be red. The beds are thin and repeated. Near 
 Thurso, it produces large and excellent flags, and is wrought ; 
 as it might be, far more widely. 
 
 Ill some parts the sandstone is often very deceptive. It is 
 occasionally white or yellow, and might be thought a portion of 
 the coal sandstones, on a superficial and hypothetical view, as 
 I believe it has been thus mistaken. But it is not difficult to 
 see that these are nothing more than the dark grey ones of this 
 deposit, rusted, and often so as to affect whole beds, by the 
 action of the weather or of internal water. It is a fact analogous 
 to many similar ones which I have pointed out in the trap clay- 
 stones. 
 
 I have lastly taken the great north-western tract of this rock as 
 one division. It is much more scattered than the preceding : but 
 as most of it is easily traced on the Map, I shall only point out 
 in addition, a small spot in Lewis, and add that Rum is included 
 in it. 
 
 Its disposition on the mainland is more remarkable than that 
 of any of the former, from its frequently occupying the summits 
 of the gneiss hills, far above the level of the sea : and these 
 numerous detached parts, taken together with those in the 
 interior of Sutherland just noticed, and with that apparent former 
 connexion which one of the sections especially traces, bespeak 
 such a loss of the surface in these parts, that I shall not dispute 
 the speculations of any one who may choose to think that most 
 of this country was once covered by a continued tract of sand- 
 stone. If the intermixture of this sandstone with the gneiss is 
 often very minute and remarkable, it will also aid in showing the 
 labour bestowed on this survey, as nothing less would have 
 brought to light facts so easily overlooked in a sweeping exa- 
 mination. 
 
 It is remarkable respecting the positions of this rock in so 
 mountainous a country, that the strata are very extensively at 
 low angles, or nearly horizontal, while the subjacent gneiss is 
 much elevated and also disturbed. It is in Sky and Rum most 
 remarkably, and in the Summer Isles, that the reverse occurs ; 
 since the contrary is often visible, though the details cannot be 
 given here. 
 
 With respect to mineral chairacter, it is very generally a red 
 sandstone, with little or no shale, and also a fine one. The con- 
 glomerates are apparently not extensive, and they occur where 
 
Geological Map of Scotland. S9 
 
 they might be expected : and I may remark, as might also be 
 expected, that the very insulated fragments, in the interior espe- 
 cially, consist solely or chiefly of the conglomerate. 
 
 Two portions alone have left doubt on my mind, and after all 
 the examination that I had the means of bestowing on them, I 
 must confess my inability to satisfy myself respecting their true 
 nature. They \yill be fitting subjects for the future investigation 
 of those who will otherwise be examining what is already clear, 
 for the purpose of finding petty faults. 
 
 In the Summer Isles, this rock is often singularly disturbed 
 and elevated, while in some of these, there are even strata at low 
 angles placed on the edges of these disturbed ones. Under the 
 general belief of geology, these ought to be distinct and distant 
 deposits. There are persons who will assert that the upper one 
 is the red marl sandstone. This may be ; considering the sin- 
 gular positions and the neighbourhood of the lias series ; but if 
 I have laid down such a portion of red marl at Loch Greinord, 
 I could not eq^ually satisfy myself in those islands, since I had 
 not sufiicieiit time to spend on so long and difficult a labour as 
 the navigation of so many islands often implies in this stormy 
 climate. In the mean time, they are all laid down as the old red 
 sandstone ; while this annotation will suffice to point out a pos- 
 sible correction. 
 
 In the sandstone of Sleat in Sky, there occurs a quartz rock 
 among the elevated portions. On the prolongations of this rido-e 
 to the Kyles, and also on its continuation upon the main Ian’S, 
 the sandstone, if sandstone it be, is elevated and often reversed i 
 it is the most disturbed stratification that I know of in Scotland. 
 The flatter red sandstone of Sky is doubtless that now under re- 
 view : but what is this ? The action of trap might produce on 
 it the effects which are visible. But it is more often pale or 
 white than red. Under different examinations, in different years, 
 I have doubted, and changed its indications. I have thought it 
 a primary red sandstone ; a quartz rock, on which the true red 
 sandstone lies ; and the red sandstone itself, elevated by the trap. 
 Finally, I know not what to conclude: and if it remains as I first 
 of all laid it down, it must also be left to future investigations to 
 determine what it really is. But it is not so easy an investigation 
 as a superficial geologist would imagine : althou2;h that wTll not 
 prevent the first tyro who shall examine it from "boldly decidiiio- 
 on its nature. ® 
 
 The remarkable elevations and disturbances of the sandstone 
 of Rum may be accounted for by the trap. I may pass to the 
 coal series: since I can add nothing of any moment to what I 
 was elsewhere obliged to say respecting the mountain limestone. 
 
 This forms that portion of the geology of Scotland, which, 
 while it was of the highest importance as a subject of statistics’ 
 has also demanded the most labour, from its extreme intricacy 
 and difficulty. When I commenced this investigation, it was 
 
90 Memoirs to IL M. Treasury respecting the 
 
 said that the coal of Scotland formed one broad field extending 
 from sea to sea, though no attempt was made to define its boun- 
 daries. It was known also that there was coal in Sutherland, 
 that it had been wrought in Mull and Sky, in a trifling manner, 
 as also that it was wrought at Campbelltown and at Canobie. But 
 this was all. The geologists of Scotland had investigated no- 
 thing ; and though the coal- viewers knew that the coal of Camp- 
 belltown and Sutherland differed from that of Fife and Glasgow, 
 geological knowledge had not sufficiently spread among them to 
 enable them to see where the essential distinctions lay. Nor 
 had even these men, often remarkably able and enlightened, at- 
 tempted to investigate any of the boundaries of the proper coal 
 series : though it is to them that we owe all our information as 
 to the details of that which it was their great interest to ascer- 
 tain ; as, among these, I must chiefly name the authors on this 
 subject, Mr. Williams and Mr. Bald. And as it is not my inten- 
 tion to record matters of this nature, since they lay beyond the 
 boundaries of my investigation, and could but have been com- 
 piled from the information of others, I must here refer to the 
 writings of those two accurate surveyors for information which 
 I need not abridge. 
 
 It was a consequence of this ignorance, that while the dis- 
 tricts wliich might possibly contain coal were unknown aud un- 
 defined, there could be no anticipation of the places in which it 
 might be sought. But it was another, and had often proved an 
 evil one, that coal-viewers, either ignorant or fraudulent, and 
 sometimes proprietors of land equally ignorant, undertook to 
 seek for coal where it was impossible that it should exist : as it 
 is also well known that much money has at several times" been 
 wasted on these purposeless pursuits. And when I say that the 
 wretched and scanty lignites of Sky, and more particularly of 
 Mull, had thus been pursued under the belief that it was the 
 proper coal series, and further, that considerable sums were ex- 
 pended in seeking for coal in the primary territory of Isla, it is 
 a sufficient proof of some of the consequences of this ignorance. 
 
 The useful great result of the present survey therefore will be, 
 first, to have marked all the places where coal may exist, though 
 it should not be known, and thus to direct future researches ,* 
 and, secondly, to mark the limits beyond which it needs not be 
 sought, as it assuredly will never be found. Thus may the fu- 
 ture waste of money be prevented : while if the settlement of 
 this point should do no more than save the restless anxiety of 
 proprietors of land on this subject, it will have effected a most 
 valuable purpose: as few that are not extensively acquainted 
 with those, can believe how widely this anxiety, with a belief or 
 conviction of the possession of unknown coal, is spread among 
 them. Every man may now at least see what his property is 
 not, and cannot be, in this respect; though, in the opposed 
 case, he cannot be sure of what it is. Yet, even here, he will 
 
91 
 
 Geological Map of Scotland. 
 
 be satisfied that there is probability, or otherwise, and thus be 
 guided by the joint amount of this, and of his desire and power 
 in speculating on such researches. 
 
 Beginning at the south, though it was known that there was 
 coal at Canobie, since it was wrought, and though borings had 
 been made at Oikel and Ruthwell moors, and elsewhere in the 
 neighbourhood, as the coal series was fully exposed on the shore 
 at Ardbigland, it was not known that these were parts of an ex- 
 tensive coalfield continuous with another portion of the same 
 beyond the Scotch border. I have ascertained and defined this 
 coalfield as far as the summit of the Carter-fell, where it is lost. 
 
 But as the Map shows better all that I could say respecting 
 its limits and bounds, and as I need not enter on things so fami- 
 liar as the nature and position of this series, nor attempt to give 
 lists of ever vacillating positions, I shall confine myself to the 
 few following remarks : leaving it also to the coal-viewers to give 
 their own details of the Canobie coal mines. Though the borings 
 had not sufficiently ascertained it, as they are recorded by Ge- 
 neral Dirom, there is abundant apparent evidence that from 
 Ardbigland as far as Hoddom and Middlebie, and probably even 
 to near Langholm, the wear of the surface has left nothing but 
 the lowest portions of this series remaining, if there ever was a 
 greater depth of it, and that it is very unlikely to be a repository 
 of actual and useful coal. In some places indeed it is so shaved 
 down to the red sandstone, that but for the evidence of the borer, 
 its existence might not easily have been suspected. And I have 
 thus found great difficulty in representing it on the Map under a 
 definition approaching to what may be the truth. 
 
 From Langholm through Liddisdale it forms a much deeper 
 body of mountain land, though its lower surface, in contact with 
 the red sandstone, is often visible in the vallies and beds of rivers. 
 Yet though I have searched every accessible point here, as far as 
 my other needful labours admitted, I have never found an indi- 
 cation of coal, and scarcely even of shale. It is a solid mass of 
 white sandstone ; and, at Langholm itself, is many hundred feet 
 thick. 
 
 Yet it must not be pronounced that there is no coal in this 
 portion ; as there is in that near to Canobie. It must be for the 
 great proprietor of this tract to inquire of this, if he thinks fit, 
 through adequate coal-viewers : but the general difficulty, as far 
 as a mere geological surveyor can go in such a work, seems to 
 arise from the fact that the strata are commonly at low angles, and 
 little disturbed ; whereas in the central great coalfield of Scot- 
 land, the frequency of trap is ever bringing it to light, by turning 
 up the fractured edges of the body of strata. Lastly, I need 
 only add, that on the Carter-fell, this field thins away to a mere 
 skin, in some places, of the sandstone, though in England, at no 
 great distance, it contains coal. It may perhaps be better inves- 
 tigated hereafter by joining the examination of the adjoining 
 English portion and this together. I do not find that the former 
 
92 
 
 Memoirs to H. M4 Treasury respecting the 
 
 is very accurately known, and it was a work which lay beyond 
 my prescribed boundary. 
 
 1 need not describe in words any thing that respects the posi- 
 tions and boundaries of the detached tracts in the great central 
 coalfield, since the tint that has been chosen for it renders it 
 very visible ; except perhaps near Girvan, whence I here note 
 that small portion. 
 
 I have called it one coalfield, because thus at least will geo- 
 logy view it, though coal surveyors will divide it into separate 
 portions, as they will also limit that term to the tracts in which 
 coal is actually wrought. It must be viewed nevertheless as one 
 great and single deposit : and whenever its portions are sepa- 
 rated, it is either from the elevation, to the surface, of the inferior 
 sandstone, or the waste of that surface, or the presence of trap, 
 breaking up and dividing the strata in some places, and over- 
 whelming them in others. The former remarks on the red sand- 
 stone supersede all that I might otherwise now have said on the 
 first of those subjects, as the subsequent ones on the trap will do 
 all else that is required. 
 
 On the positions of the strata in this great field, 1 need but 
 repeat what I have said of the red sandstone. They are different 
 in almost every place, they are especially discordant and irregu- 
 lar near the trap masses and veins, and nothing but a volume, 
 after years of minute examination bestowed on that single object, 
 could convey any notion of them, as even then the information 
 would be extremely limited. But I may make one practical 
 general remark ; while I have not found, that as a leading fact, 
 it is sufficiently known to the coal-viewers. As the intruding 
 traps have visibly turned up the edges of the mountain limestone 
 in many places, so, in turning up the whole mass of strata, do 
 they render the coal beds more accessible. It is the peculiarity 
 and number of the masses of trap in Fife that have rendered this 
 county so remarkable for its coal mines. But for this series of 
 violent posterior actions, accompanied by the incumbrances in 
 working, of which the miners so often complain, and with appa- 
 rent reason, it is probable that comparatively little of the coal of 
 this coalfield would ever have been known or wrought. And 
 thus also if the trap has destroyed or overwhelmed much, it has 
 apparently far more than compensated that evil in rendering the 
 remainder obvious and accessible. I need scarcely add, that 
 coal-viewers will be thus directed to the points where coal is 
 most likely to be found ; and if they complain of the evils of 
 intruding trap, they must also be content with it for the sake of 
 the good. 
 
 If it is from this reason probably in a great measure, that the 
 actual existence of coal beds over this large space seems very 
 limited in proportion to the whole surface, so must it not be con- 
 cluded that these beds are as partial as they appear to be. 
 What they may be, in numbers or extent, or where to be found, 
 no one can now conjecture : yet it might not be a very rash con- 
 
Geological Map of Scotland. 03 
 
 elusion that they are very general over the whole, wherever at 
 least the mass of strata is not bared down to almost the very 
 surface of the red sandstone. 
 
 Thence, in addition to the speculative views which anxious- 
 minded people may take respecting the exhaustibility or other- 
 wise of the Scotch coal, there is a rational prospect opened, of 
 boring for coal beds more freely than has yet been done, wher- 
 ever the positions of the strata and the nature of the ground do 
 not allow the edges to be seen at the surface. But if I cannot 
 venture to say more on this subject, which must ever be one of 
 economical speculation, I must here urge as a general rule, the 
 folly of seeking for coal beneath the red sandstone in eithw of 
 these coalfields, since it is a prejudice or practice not yet over- 
 come, partly from ignorance of the true position of the coal 
 series, and partly also from some false opinions, of geologists as 
 well as of coal-surveyors, respecting the nature of the sandstone 
 itself in some places. It is true, that coal does occur in the old 
 red sandstone, as is the case near Dunbar, so as even to be par- 
 tially wrought by the neighbouring country people, and as it 
 once was in Arran. When it does appear, it may doubtless be 
 wrought, if expedient : but it is never worth seeking for, and far 
 less worth boring after; since it is always scanty, generally bad, 
 and might not be found in one of ten thousand attempts. 
 
 The false opinion respecting some of this red sandstone, to 
 which I have alluded, is this. Geologists unacquainted with 
 more of Scotland than a casual journey, or the sight of a single 
 portion of this sandstone could teach, looking at things super- 
 ficially, very often incapable of correct observation where so 
 many plunge into a subject for which they are in every way un- 
 prepared, and those above all who make England a standard for 
 every thing, and judge from an hypothesis, which is not even 
 their own, but borrowed from those who have ascertained nothino- 
 themselves, these persons have reported that many parts of the 
 md sandstone of Scotland were the red marl ; while, if such, 
 it must have been superior to the coal series. The practical evil 
 of this error is too great to allow it to pass without a censure 
 which has been spared on all other similar errors when these 
 related to nothing but the mere science of geology ; and that it 
 nray be effectual as to those interested in the right and the wrong, 
 it ought not to have been less marked. 
 
 I have examined all these sandstones, and traced their con- 
 nexions in such a manner as to leave no doubt : as others may 
 judge, whose decisions are most worthy of regard. And the 
 conclusion is equally true of that red sandstone on the English 
 border. The English geologists may inquire, if they please, into 
 their reasons for deciding that the adjoining sandstone of Eng- 
 land is the red marl ; but if my own opinion that the Scotch 
 portion at least is the old red sandstone, be not deemed valid, 
 the appeal may be made to the miners of the Canobie coal, or to 
 Mr. Bald; judgments, I imagine, which no one will venture to 
 
04 
 
 Memoirs to H. M. Treasury respecting the 
 
 reject or oppose ; while their experience uniformly agrees in the 
 fact that the coal is invariably above this red sandstone. 
 
 I have already said, more than once, that it is not within my 
 limits or undertaking to enter on the question of the actual work- 
 ing of coal in Scotland. And this applies equally to the plans 
 of those works, and to the details of the actual coal beds, in the 
 series, of which it was my duty to give the superficial extent, 
 and scarcely aught more. I could not have done more from my 
 own knowledge : and as far as it is not already compiled from 
 the experience of the different coal-surveyors and miners, it must 
 be done by others, among many other matters of detail. It is 
 not a work which a general geological surveyor could have done 
 from observation ; and had he attempted it, no one would have 
 trusted him, and very justly : while, as it must have been com- 
 piled from reports, it will be far better done by practical men 
 of sufficient connexions, devoted to this single object, as, in addi- 
 tion, they are the only persons on whom the public ought to rely, 
 and on whom I should myself place any reliance. If any one 
 imagines that a geologist can, on points like this, supersede a 
 practised surveyor, he neither knows what geology is, or geolo- 
 gists are. It is for the same reasons that I here give no ac- 
 count of the ironstones in the coal series, or of the shales which 
 may be wrought for alum. These cannot be anticipated by any 
 scientific knowledge. They will be found by chance ; and where 
 they have been found, they are known to those who alone have 
 any interest in them. And if I have seen alum slate in places 
 where it was unknown, it needs not be said that there is more 
 than enough of this material in the places where it is at present 
 wrought, and that the state of this manufacture and commerce 
 do not now admit of new undertakings in new places, and is very 
 little likely to do so hencefoward. 
 
 If the red marl sandstone is the next stratum of Scotland in 
 the order of stratification upwards, I have left but little to say on 
 the infinitely minute portion of it which is contained in this 
 country. I have already named what is probably to be referred 
 to this rock near Loch Greinord ; as I have stated all that 
 I know, and doubt of, respecting the Summer Islands. There is 
 but one other place where it either does, or may, exist. This is 
 in Arran, about Corrie. The portions of the otherwise united 
 red sandstone which lie above the limestone at that place, may 
 belong to this rock. But they may also be but a part of the 
 inferior sandstone, since the limestones of this character, and 
 containing the same fossil shells, often occur in this. It is a 
 matter of infinite indifference what the fact is : and if a fanciful 
 importance has been attached to it, it is by the very ignorant 
 and hypothetical persons who have referred so much more 
 of the red sandstone of Scotland to the red marl, under 
 an utter ignorance of the country at large, and not a much 
 greater talent in making distinctions on this subject; while, 
 in lieu of this, deciding in a much more expeditious and less 
 
Geological Map of Scotland, 95 
 
 laborious manner, under a previous hypothesis. All do not 
 know what those persons are : he v»^ho does know them will 
 know also how to value their opinions and decisions ; as he also 
 cannot fail to be aware that they who are incapable of observino* 
 for themselves, seek for a poor fame in controverting the deci- 
 sions, and connecting, whether justly or not, the observations of 
 those who have taught them even the little which they know. 
 
 Had I been merely writing on the science of geology, I should 
 have spared this and other similar remarks; since Truth, in 
 every thing, has ever had the same complaints to make, while 
 emerging at length in all its brightness ; and as he must be not 
 only very inexperienced in science and literature, but very defi- 
 cient in self-possession, who cannot exert that moral deafness to 
 false criticism, under which alone he can experience peace. But 
 the question here is of a far other importance ; since it is not one 
 of speculative opinions, but involves the very end and purpose 
 for which the present survey was instituted ; the terrestrial sta- 
 tistics and the consequent commercial enterprise of Scotland. 
 Not to be thus pointed in providing against previously incorrect 
 statements, and against that renewal of them which must be 
 expected, would be a dereliction of duty: since it would be to 
 leave an important economical question still open to dispute, or 
 else to suffer enterprising persons to waste their means on vain 
 speculations. He who may believe the red sandstone of Canobie 
 and the neighbouring tract, or that of Hamilton, to be the red 
 marl, may be there induced to seek what he assuredly will not 
 find. 
 
 And, as I have no other opportunity of noticing this insulated 
 fact, I may here point out the white sandstone in the west side 
 of Arran, which is so entirely insulated, and so devoid of all 
 specific character, that, in such a disjointed place as this, it may 
 be referred to any thing. I am utterly indifferent whether it is 
 referred to the old red sandstone, the proper coal series, or the 
 green sandstone above the lias, since it might be argued in 
 either way, and there is no evidence as to either. The contests 
 of geological opinions are of as little value as the subject is 
 without other interest than its utility : and this will not be af- 
 fected by the decisions of those persons. 
 
 I have already said in another place, that there is no reason, 
 in Scotland, for distinguishing the lias, the oolithe, and the green 
 sandstone, in any other manner than I have done in the Map, if 
 even that were possible ; and I shall therefore here speak of the 
 whole together, while I have not left much to say respecting 
 these singularly scattered fragments of a deposit which occupies 
 so little superficial space compared to its extent. 
 
 As far as the Map itself may render the finding of these often 
 nearly microscopic patches of colour difficult, I have attempted 
 to amend this in another notice, and I must now trust, that be- 
 tween both, their places will be found. I am very sure that they 
 will be found in nature ; and, as far as an inch can represent 
 
90 Memoirs to H. M. Treasury respecting the 
 
 four miles, in the exact places noted ; since, from its peculianty, 
 this miserable fragment of the geology of Scotland was exatnmed 
 with even more care than it deserved. And all further that I 
 need here say on its place, or rather places, is, that its extent, 
 such as that extent is, reaches from Machrihanish Bay to the 
 Shiant Isles, on the west, as, on the east, it is of no greater a 
 one under any indication, than from Cromarty to Nairedale m 
 Sutherland. It thus skirts the western shores of a portion of 
 Scotland, but under an extreme inequality ; nor is a trace of it 
 visible any where else i while I leave it to others to speculate, 
 whether a series of strata so very conspicuous in England as to 
 form a large portion of this part of our island ever occupied a 
 greater extent in Scotland, or if they never were deposited in any 
 other places. And any one, as well as I, can further speculate 
 how far the position of these strata as they now stand, depends 
 on their original extent, the effects of the intruding trap, and the 
 waste of the land, separately or united. 
 
 The very slight description to which I must here confine my- 
 self will be rendered most clear by taking each portion sepa- 
 rately, and I will trace the western side from the south. 
 
 At Campbelltown, or rather Machrihanish Bay, this series is 
 wrought for coal ^ but that is a lignite coal of a very bad quality, 
 and now, of very limited use. 
 
 The next portion occurs in Mull. The ehief visible extent ot 
 the limestones is in the southern cliffs, and these strata re-appear 
 under the trap on the north-eastern shore, in the place marked 
 on the Map : though when I say under the trap, I should add 
 that it has here partly disappeared, so as to leave the surface 
 bare. It is also bared near Carsaig ; and here the green sand- 
 stone is visible. Here it was that money was once expended in 
 seeking for coal, but with no useful result. On the north- 
 western side of the island, near Inch Kenneth, a considerable 
 mass of the limestone is visible, but of no great extent, and Inch 
 Kenneth itself consists of the green sandstone. 
 
 The Map shows though imperfeetly, for want of sections, the 
 manner in which this series occurs in Morven ; but such sections 
 will be found in my work on the Western Isles. The has is 
 especially visible on the shores, particularly about Loch Aline, 
 where it might easily be wrought were there not better lime- 
 stones in competition at Lismore and in Sky. Its singular posi- 
 tion on the summits of some of the hills, is noted in the sections 
 referred to, as not being well capable of entry on this Map ; and 
 it is apparent that it every where comes to light as edges of 
 strata covered by trap. A little lignite coal occurs in these, on 
 the hill summits : and I may remark generally, that in these 
 southern fragments, none of the strata usually intervening be- 
 tween the primary rocks and this series are present. 
 
 This series oceurs again in four distinct fragments, on the 
 shores of Ardnamurchan, at Camusmore in Muck, and on the 
 north side of Eig. Here it is visible only in the vertual cliffs. 
 
Geological Map of Scotland, 97 
 
 und is interstratified with trap, as well as covered by it. One or 
 two of the sections in the book referred to represent this better 
 than words could do. 
 
 In the district of Shalts in Sky, the extent of the lias is consi- 
 derable, while it also forms Pabba, and skirts the southern shore 
 of Scalpa. It is here that the influence of trap has converted 
 considerable patches of it into crystalline limestones of different 
 colours. In some places, this is pure white, and one spot was 
 partially wrought. It proved useless at that point, by being inter- 
 sected with trap veins, and the search was not prosecuted. And 
 as commerce knows that foreign marbles can be procured at a 
 cheaper rate, those at this spot are not likely ever to become 
 subjects of economy. 
 
 The point of Aird consists of the green sandstone, considerably 
 calcareous in parts, covered in most places by trap, and intersected 
 by trap veins, as a fragment also appears at Hunish point. The 
 course of these strata fcneath the trap can be traced on the Map 
 along the eastern shore, and also at Duntulen ; and some of the sec- 
 tions in the same work show a few of the remarkable disj unctions and 
 positions. But the Map could not show, that at some points in 
 the interior, northerly, fragments appear where the trap has been 
 removed ; rendering probable a considerable, if not a total con- 
 tinuity beneath. There have been found, in several places in this 
 north part of Sky, fragments of lignite, and with the usual effect 
 of exciting the hopes of coal. I need now scarcely say that 
 there can be nothing here worth a further inquiry. 
 
 In Raasay, the quantity of visible limestone is very small, and 
 lies on the south-eastern shore ; though in the same sections, I 
 have, for the sake of geological explanation, rendered it more 
 extensive. And here also the red sandstone intervenes between 
 this series and the gneiss. But the green sandstone fonns a mass 
 of enormous thickness, though generally covered by the trap 
 porphyry of this island. And here the possibility of interminable 
 quarrying equals the perfection of this material as a building 
 stone, while, in summer at least, the shipment would be imme- 
 diate from the quarries. It is for the proprietor, and others, to 
 inquire of the commercial purposes to which this might be turned, 
 if indeed the quarries of Arran would permit of a competition. 
 
 The last fragment of this series occurs in the Shiant isles, if 
 indeed it ought not rather to be called an indication. But for a 
 previous analysis of the whole of this most difficult piece of in- 
 vestigation, it could not have been suspected, though it had 
 been seen. It consists in a minute quantity of shale, entangled 
 in the trap at one or two very small points. 
 
 On the east side I may barely note the disjointed fragments 
 south of Cromarty, giving the usual indications. The Suther- 
 land portion is conspicuous. But it demands no other details 
 here than the Map will indicate, while its economical description 
 is unnecessary in this place, and also beyond my bounds. Mr. 
 Williams’s work can be referred to, as may a paper of my own 
 
98 Memoirs to H. M. Treasury respecting the 
 
 in the Quarterly Journal ; as every thing which relates to this 
 subject is also well known to the noble proprietor of this territory. 
 
 The last rock which remains for annotation, is the trap : and 
 I have already indicated, in another Notice, the distinctions here 
 adopted, as to these rocks and the older porphyries, together 
 with the reasons for those, and for the general colour by which 
 the whole, however different, have been here indicated. 
 
 With the exception of a few of the veins, which also I have 
 pointed out in words, in the same Notice, the trap will every 
 where be visible on the Map, with a little care; while, however 
 scattered and unconnected it may often be, 1 must, for conve- 
 nience, take it as if in three divisions. 
 
 The first of these lies to the south of the southern slate, the 
 next is that which is so widely scattered over the space that 
 intervenes between the northern and southern divisions of the 
 primary rocks, and the third includes chiefly Sky and Mid-Lorn 
 at its two extremities, while the Map will point out the interme- 
 diate portions. That which occurs in St. Kilda and the Shiant 
 isles cannot well be united with this last, and I may therefore 
 note these first. 
 
 St. Kilda is an entire mass of trap, divided pretty equally into 
 an augit rock, and a syenite of a pale grey not exceedingly diffe- 
 rent from that of Ailsa, and sometimes resembling that of Arran, 
 termed granite. The great mass of trap in the Shiant isles forms 
 all those islands, with the exception just noticed, displaying 
 great ranges of columns ; while a more minute description of it 
 will be found in my book on the Western Islands. 
 
 In the southern division of Scotland, the leading mass is that 
 which is continuous with England under the same rock, includ- 
 ing the Cheviot, and I have already stated all that seemed neces- 
 sary respecting its characters and its difficulties. Nor do I find 
 anything of importance, in addition, to remark respecting the 
 various patches which are scattered about from Dunse to Tuen- 
 dergarth. How far these may have been originally connected, it 
 is not necessary here to speculate. 
 
 In the central district, the most remarkable circumstance is the 
 great leading mass which commences at the sestuary of the 
 Clyde, and which, though interrupted, may be considered as 
 stretching eastward till it splits into the two divisions which skirt 
 the north of Fife and form part of the Sidlaw hills ; while at its 
 western extremity it is continuous with a great mass which is 
 marked by Strathaven and Loudon. The next which I may 
 point out relates to the scattered masses which skirt the northern 
 primary border, few as these are ; and the interest attached to 
 those which skirt the southern slate northwards is of the same 
 nature. These, with the numerous masses scattered over the 
 remainder of this great tract, seem to indicate a once much more 
 wide and continuous connection, as there are persons who may spe- 
 culate whether it was not once so universal as to have covered the 
 whole of this district with trap. And why this trap, like the southern 
 
99 
 
 Geological Map of Scotland. 
 
 one, should be especially connected with the secondary strata, 
 and not give similar indications of having covered the primary 
 ones, is another of those speculative questions which do not 
 form an object in this Report. 
 
 The marks of great waste, however, are abundantly evident ; 
 while on the same eastern portion of the country, where the 
 primary strata of Aberdeenshire exhibit the peculiar marks of 
 waste formerly noticed, the trap seems also to have been more 
 removed than to the westward. 
 
 Wherever occurring, the patches of trap, whether originally 
 independent or the result of waste, are of very unequal magni- 
 tudes; while Fife, with the opposed proximate land south of the 
 Forth, display this intricacy in the most remarkable degree, en- 
 hancing exceedingly the labour of investigation. 
 
 It would be equally tedious and unnecessary to describe the 
 external features of these endless masses : the total history of 
 the whole would occupy a volume : and I do not here intend to 
 write volumes for geologists alone : while lastly, respecting this 
 district, I need only further point out the outstanding masses, 
 in the islands of the Forth and those of the Clyde, including 
 Ailsa, lest any of them should be overlooked. 
 
 Respecting the mineral characters of the traps over this great 
 tract, I can but notice some of the most striking circumstances, 
 as the detail of the whole would be equally endless and useless. 
 
 I formerly said all that I can here afford to do respecting the 
 peculiar traps of the Tinto and Pentland range. 
 
 That of Ailsa deserves notice from its singularity : containing 
 but atoms of hornblende in a base of compact felspar. 
 
 In the Little Cumbray it is often a vesicular claystone, no way 
 differing from the scoria of volcanos. 
 
 In Arran, the varieties are peculiarly numerous : presenting 
 clinkstone, with various pale claystones and porphyries, besides 
 the more usual blue claystone ; as the former appear to be the 
 produce of a partial decomposition. Here also is the chief re- 
 pository of the pitchstones of Scotland ; while for the minuter 
 particulars of this and the other Clyde islands, I can refer to my 
 book on the Western Isles. 
 
 Of other peculiarities in this great trap district, I may notice 
 the exceedingly compounded greenstones about Glasgow, the 
 greenstone with red felspar near the Queensferry, the claystones 
 producing prehnite and geolites in the Kilpatrick hills and near 
 Beith, the remarkable porphyry at Lentrathen, the not less 
 remarkable rocks, including fragments and nodules, near Biggar 
 and near Dirleton, the porphyries of the Ochil hills, and the 
 rocks between Montrose and the Redhead. But as the minute 
 details of all this are beyond my limits, I may conclude by 
 saying generally, that the predominant traps where 1 have not 
 made the greater exceptions in this district, are claystones of a 
 dark colour, and greenstones, while the former very far exceed 
 
 H 2 
 
100 Memoirs to H. M. Treasury respecting the 
 
 the latter. The true greenstone, of hornblende and felspar, is, 
 in Scotland, a rare rock. An original blunder, long persisted 
 in, gave this name to augit rock, which I long since distinguished 
 and added to the system. 
 
 In that which I have here separated as a third and the last 
 district, I will first notice the outstanding portions, lest they 
 should be overlooked in the Map. The two rocks at Loch 
 Maddy, and an island in the sound of Isla, are the most re- 
 mote of these : those in the small islands of the Oban coast, 
 and those connected with Sky, will easily be found : if at least 
 the copiers do not forget them. 
 
 Here, as elsewhere, it is left to others to speculate on the 
 former unity or connection of these separate tracts : and with 
 respect to the general characters and geological circumstances, 
 the account which I have given in the work on the Western Isles 
 is so full and minute, that it would be superfluous either to 
 repeat or abridge it here, if even my plan admitted of such de- 
 tails. The only tract not there described is that of Mid-Lorn : 
 and respecting that, I do not perceive there is anything left to 
 say beyond what I was compelled to notice in the other Reports : 
 as far at least as the plan of the present one extends. 
 
 The whole of this tract nearly, is a simple claystone, some- 
 times becoming a clinkstone : while some of its minuter pecu- 
 liarities, visible on the sea coast, are described in the above- 
 mentioned work. 
 
 Mull and Morven present little else that is remarkable : but, 
 at any rate, the description of their rocks will be found in the 
 same place. 
 
 In Canna, the most remarkable rock is the claystone porphyry 
 containing glassy felspar ; and in Eig, the columnar porphyry 
 of the Scuir, with the two pitchstone veins of the same island. 
 Rum consists chiefly of augit rock ; and its characters here are 
 very distinct. It had always been confounded with greenstone, 
 as I have just remarked: while it was by mistaking augit for 
 hornblende that this name was invented, since it is a greenish 
 compound. If I have now separated these, and made a new 
 species of the present, so have I very widely extended the reign 
 of augit rock, even to the exclusion of many imaginary clay- 
 stones and basalts. 
 
 The same compound prevails on the north-eastern coast of Sky: 
 which contains every known variety of the traps. About the 
 Cachullin hills is found hypersthene rock, as it also is in Aird- 
 namurchan; as yet not certainly known anywhere else, and 
 added by myself to the former catalogue of rocks. The hills to 
 the north of Strath are of pale and reddish claystones, porphy- 
 ries, and sienites ; as here also lies that rock which, in mineral 
 composition, is a true granite, on which I have made many im- 
 portant remarks in my various works. The other varieties or 
 species, as being of more ordinary occun’ence, I need not specify. 
 
Geological Map of Scotland. loi 
 
 Finally, I may point out the porphyry of Raasay as one of the 
 most striking exceptions to the prevailing characters of the recent 
 trap rocks. 
 
 Of the economical applications of these rocks it seems quite 
 superfluous to say any thing. Nothing can be more familiar : 
 and whatever confusion the working classes concerned with rocks 
 may make in other cases, this is one which they never mistake. 
 And though I might point out the varieties which are best fitted 
 for the purposes to which it is applied, every quarrvman can 
 equally determine the best material among the rocks within his 
 reach. 
 
 This completes all that I find it necessary to say in explanation 
 of the Geological Map of Scotland, in addition to what is con- 
 tained in the other accompanying Notices. 
 
 H 3 
 
102 
 
 Memoirs to H. M. Treasury respecting the 
 
 NOTICE 
 
 RESPECTING THE 
 
 KEY TO THE GEOLOGICAL MAP OF SCOTLAND. 
 
 Sir, 
 
 THE colours used to express the rocks on the Map are 
 eic^hteen. They are represented on the Key in their pure form, 
 since they are on white paper. Hence they would be found to 
 correspond with the same colours on sections, because these are 
 equally placed on a while ground ; but their correspondence with 
 the colours on this Map is much less perfect, with the exception 
 of a few of the more conspicuous and pure, owing for the most 
 part to the blackness of the engraving, and occasionally to the 
 very small spaces which they occupy. Hence it will be useful, 
 in case of the publication of this Map, to name the colours and 
 mixtures which have been used ; as the colourists will thus more 
 easily render the copies correspondent to the original. 
 
 Granite. — Burnt terra di Sienna. 
 
 Gneiss. — Gamboge. 
 
 Mica Slate. — An olive, by a mixture of gamboge, Prussian 
 blue, and burnt Sienna. 
 
 Quartz Rock. — ^The purest green that can be produced by 
 mixing Antwerp blue and gamboge, but tending to yellow. It 
 is necessary that this colour be extremely bright and pure on the 
 Map because the blackness of the engraving lowers its tone so 
 much, as often to make it difficultly distinguishable, especially 
 in small spaces. 
 
 Clay Slate. — The same colours, so apportioned as to make 
 a blue green. This must also be kept very clear, owing to the 
 same cause. In certain approximations with Prussian blue, used 
 to represent trap, it sometimes becomes difficult to distinguish 
 those two colours on the black engraving ; in which case the 
 particular portion of this green in contact has been rendered 
 more yellow by additional gamboge. They who may inspect 
 the Map must recollect this circumstance, lest they might imagine 
 that a different rock was intended. 
 
 Chlorite Series. — The colours mixed for this tint are the 
 same as for mica slate, but with a larger proportion of the Sienna, 
 so as to produce a brown olive. 
 
 Prim ARY Limestone.— This is pure ultramarine, and it ought 
 to be that which has the bluest tone, as the purple one may be 
 
103 
 
 Geological Map of Scotland, 
 
 confounded with the Prussian blue of trap, where the engraving 
 happens to be dark. It must also be applied thick, that it may 
 be conspicuous in the very small sjDaces which it occupies. 1 do 
 not think that cobalt blue shows quite so strong, though the tone 
 of colour may be the same : nor do 1 think that it can be trusted. 
 This is intended as a caution to the colourists : as its superior 
 cheapness offers a great temptation to substitute it for ultrama- 
 rine. 
 
 Serpentine. — This is yellow orpiment. The spaces being 
 very small, it must also be used in a good body. 
 
 Porphyry. — This is a purple, from a mixture of lake and 
 Antwerp blue. Where the spaces are very small, and the en- 
 graving very black, as on the summit of Ben Nevis, it is necessary 
 to make it very red, as it is otherwise invisible. Though it might 
 be confounded on the dark Map, with the colour for red sand- 
 stone and that for shale, the geological connexions will prevent 
 any error among geologists ; as others may consult that science, 
 in case of doubt. 
 
 Old Red Sandstone. — Pure lake, considerably dilute. 
 
 Mountain Limestone. — The same, made sufficiently strong 
 to distinguish it from the former ; but in the very few larger masses 
 that exist, it must not be made so heavy as to deform the Map. 
 In the greatest number of places, however, as it occupies very 
 narrow lines, it must be made as full as the colour admits, 
 without which it is often not sufficiently distinguished. 
 
 Shale OF the Old Red Sandstone. — The same mixture 
 as for porphyry, but bluer. Occurring only in Caithness, to such 
 an extent at least as to have demanded a special notice, and in 
 gradation with red sandstone, it cannot be mistaken. 
 
 Coal Series. — This is yellow oker. Over large spaces it 
 may be very dilute ; but in small ones, and on the dark engraving, 
 it requires to be considerably strengthened. In all cases indeed, 
 the colourist must use discretion in the quantity of colour, so as 
 that the dark and light parts of the Map may, under any one 
 colour, always appear as nearly of the same tone as possible. 
 
 Red Marl. — This is that burnt oker which, in most colour 
 boxes, is termed light red. It occurs but in one place, forming 
 two very small spots on the shore at Loch Greinord. I fear that 
 it may be here overlooked ; but perhaps this remark may suffice 
 to call attention to it. 
 
 Lias and Oolithe, with Coal. — This is the liquid verdigris 
 used for staining maps. As it generally occurs in very narrow 
 lines, it may be used strong. In Sky, and on the east coast of 
 Sutherland, forming broader portions, it should be dilute, as it 
 otherwise becomes too conspicuous, and deforms the colouring. 
 It is however a very doubtful and suspicious colour, often fading 
 after some time. I know not how this bad result can be reme- 
 died : but there was no other sufficiently conspicuous colour in 
 my power. 
 
 H 4 
 
10 4 Memoirs to IL M. Treasury respecting the 
 
 Green Sandstone. — 1 could find no spare, unoccupied, 
 colour applicable to this rock, from the exceedingly small spaces 
 which it occupies, rendering all degraded tints undistinguishable. 
 I have therefore repeated the yellow oker, as maintaining a sort 
 of geological, or rather mineral analogy, between this and the 
 coal sandstones. But the proximity of the lias will always be 
 sufficient to distinguish the intention of the yellow ^ or, wherever 
 the oker tint is attended by that of verdigris, it signifies the 
 green sandstone. 
 
 Trap Rocks.— This is a Prussian blue. The tint should be 
 low, at least over the larger spaces, as it becomes much dark- 
 ened by the engraving; and being also generally near to the 
 yellow of the coal series, produces a very heavy effect by the 
 contrast. Where it is used to denote small spots and veins, it is 
 scarcely to be discriminated from the similarly small touches of 
 ultramarine used to distinguish primary limestone. Nor have 
 I been able to find a remedy for this, on so contracted a scale 
 and so black a Map : it is one of the evils inseparable from a 
 work executed in so heavy and dark a manner. 
 
 Diallage Rock.— The colour selected for this is vermilion; 
 and being in approximation with the orpiment of serpentine, may 
 easily produce an effect of offensive splendour, unless both are 
 carefully managed ; but as it occurs in Shetland only, it will not 
 be found in this Map. 
 
 It is the usage, and an unavoidable one, to engrave a slight 
 line on the plate, as a boundary to each colour, for a guide to 
 the colourist; but in nature many rocks are not so defined: 
 either they pass into each other by a slow transition, or else the 
 incumbrances of the soil prevent the boundary from being ascer- 
 tained. On the original Map, therefore, both those circumstances 
 are attended to, as well as it was practicable. Hence the 
 colourists who may copy it, must be careful not to make definite 
 boundaries where they do not exist, but to blend the neigh- 
 bouring colours into each other, or to wash them off at the 
 edges wherever this occurs in the original. They must also 
 observe that there are in this Map five uncoloured places; one 
 in Isla, another at Kildrummie in Aberdeenshire, another in 
 Arran, and two on the shores of the Solway Firth. These are 
 not forgotten spots, but intentional blanks ; because the alluvial 
 covering prevented the rocks from being seen, and the occurrence 
 of different rocks at the same place prevented them from being 
 inferred. 
 
 In the choice of colours for this Map, if I have not succeeded 
 as I wished, I have laboured to do the best which the circum- 
 stances permitted, nor was it without many calculations and 
 trials that the present system of colouring was adopted. 
 
 The number of tints distinguishable on so very dark an 
 engraving wtis found on trial to be so limited, that it was finally 
 impossible to produce the eighteen which were indispensable, as 
 
Geological Map of Scotland. 105 
 
 I have just shown. The extremely small spaces occupied by 
 many produced another unfortunate restraint, as did the fact that 
 colours so perfectly distinguishable as “ light red” and burnt 
 Sienna, became confounded in many places, owing to the black- 
 ness of the ground. Thence the disagreeable approximation of 
 colours betvveen the red sandstone and the coal series on this 
 Map, since it was found that where granite was near, the more 
 eligible light red could not be trusted. And, not to dwell on 
 these and other difficulties, it has frequently oceurred that the 
 colour which was not only most eligible, but indispensable in one 
 approximation, was inconvenient in another ; while, if this evil 
 was removed from one place, it was but to transfer it to some 
 other, and generally at a greater risk of disagreeable effects and 
 of confusion. 
 
 Under all these circumstances the following plan was adopted 
 as the best which seemed attainable. 
 
 The importance of the coal series demanded that it should all 
 be seen and recognized at a glance, and thence was a very clear 
 and striking colour used for it ; while that tint also bore such 
 a resemblance to the actual colour of the predominant rocks, as 
 to approach to the fact itself. 
 
 The same plan was pursued as to the red sandstone and the 
 trap, by choosing the colours which were most nearly analogous 
 to those of the rocks themselves, within the admissible limits ; as 
 thus also the very important distinction between the trap masses 
 and the accompanying coal and other secondary strata was 
 rendered striking. 
 
 This plan could not be pursued in the primary strata ; and the 
 next best expedient was therefore resorted to, in associating all 
 the principal ones under green, with pure yellow as the starting 
 point. Limestone alone was distinguished by a powerful blue, 
 on account of the small spaces which it occupied ; as I was com- 
 pelled to resort to a similar expedient for the lias series, and for 
 the same reasons. 
 
 For the other rocks, such as granite, porphyry and others, no 
 expedient remained but to select among the remaining visible 
 tints those which would best display them, when the spaces they 
 occupied and the necessity for distinction was considered. 
 
 I need only add, that in looking at a single tint over the whole 
 Map it will be easy to perceive that it is very unequal in strength, 
 and sometimes also in tone. This, which might appear careless- 
 ness, was designed, because it was necessary. The same quantity 
 of colour did not show the same tint on all parts of the Map, 
 nor did it show alike or effectually under all its different extents 
 and approximations. It has been attempted to remedy those 
 evils in this manner ; or by changing the tone or the intensity, 
 in such a way as to prevent any chance of error in consulting 
 the Map. 
 
 1 trust that, in case of publication, the colourist copiers, thus 
 forewarned, will attend to this, as to all else which I have here 
 
106 Memoirs to H, M. Treasury respecting the 
 
 noted for their instruction. But I cannot hold myself responsible 
 for the accuracy of the copies : experience has lonoj shown me 
 how very uncertain those are, even to gross mistakes or utter 
 obscurity. The original must remain the point of appeal in cases 
 of doubt or criticism. 
 
 Let me finally offer this remark on the subject of colouring the 
 copies which must be made, should this work be published by 
 my Lords Commissioners of the Treasury. The colours are not 
 a mere object of show, but are the very Survey itself. If the 
 copies are not the most absolute transcripts of the original Map, 
 so that it shall become impossible to distinguish each individual 
 from every other and from the original, they are not the same 
 work, nor are they the Survey which I have executed. If there 
 is any one person who may hereafter possess an erroneous copy, 
 that copy is, thus far, to him, not my Survey. Nor is there any 
 remedy for such errors or misfortunes to be found in words— 
 description is inapplicable, even to correction. Expense in 
 colouring must not therefore be regarded — it were better that 
 this Map were not published at all, than published at a price 
 insufficient to command the veiy best colouring that can be pro- 
 cured in that market of labour : — it will be worthless, and will 
 be a fraud on the purchasers, although not an intended one. 
 As the Surveyor is concerned, it is as if false or fictitious books, 
 or books abounding in error even to falsehood, were to be pub- 
 lished and attributed to an Author who has had no concern with 
 them, and thus published under the sanction of his name backed 
 by the highest authority. 
 
 I have the honour to be, &c. &c. See. 
 
 •/. MacCulloch. 
 
 To the Hon. James Stewart, 
 &c« Sec* Sec. 
 
Geological Map of Scotland, 
 
 107 
 
 NOTICE 
 
 IN AID OF THE 
 
 KEY TO THE GEOLOGICAL MAP OF SCOTLAND, 
 
 AS THE 
 
 COLOURS ON IT ARE USED TO EXPRESS THE NATURE 
 OF THE ROCKS FORMING THAT COUNTRY. 
 
 THE colours used to express the rocks of Scotland are limited 
 to eighteen, as I have observed in the preceding Memorial ; but 
 while this number of colours will not express every rock which 
 occurs in this part of the Island, using the term rock in its abso- 
 lute sense, it becomes necessary to assign the reasons for that 
 limitation, and also to explain what the Map itself could not, by 
 showing the exact purpose for which each of these colours is 
 used, in addition to that general explanation already given in the 
 Notice respecting the Key. 
 
 The chief reason for this small number of colours is, that the 
 rocks of Scotland are less numerous than those of England, for 
 which part of the Island a more extensive system of colouring is 
 necessary : a fact which I shall have occasion to point out more 
 particularly in another Notice. It is another reason, that the 
 spaces occupied by the more rare of these rocks, such as jasper 
 for example, are so extremely small, that they could not be 
 represented by any colour, especially under the peculiar circum- 
 stances in which they exist ; while to this and more, I must add, 
 that the extreme blackness of the engraving, united to the small- 
 ness of the scale, has rendered it impossible to find a sufficient 
 number of tints capable of being distinguished on such a ground : 
 whence arises that violent contrast of tints equally violent, by 
 which it was found indispensable to regulate this Map. And the 
 last reason is a geological one. It is believed, or known, that 
 certain rocks occur only in small quantities as subsidiary to 
 others, and that some which possess marked mineral differences 
 of character are but variations in a single species : as it is also 
 the usage, and perhaps an unavoidable one, in the unstratified 
 rocks especially, to give but one name to the families or species, 
 although subject to such variations of character that the indivi- 
 dual varieties, considered as mineral bodies merely, are exceed- 
 ingly dissimilar, and considerably numerous, as is particularly 
 the case in those of the trap family. 
 
108 Memoirs to H. M. Treasury respecting the 
 
 Under this last reason the details are of such a nature, while 
 they comprise almost every rock, that it will be necessary to 
 enter on a somewhat wide description of the rocks in question as 
 they occur m Scotland i while the result will be such, that a fur- 
 ther Notice in addition will suffice to comprise all that needs be 
 said respecting the geological structure of that country, and in 
 aid of the Map itself, under the restrictions to which it has been 
 judged right to limit these Reports. 
 
 There is but one colour used for all the granites of Scotland, 
 nor could it have been otherwise, from not knowing where to 
 stop amid the endless diversity of those, and from the impossi- 
 bility of distinguishing them by any mode of colouring. Of this, 
 however, there can be no complaint ] since such is the universal 
 usage. The further Notice on this subject will explain, as far as 
 is needful, what those diversities are. 
 
 It is the same with regard to gneiss, and for the same reasons ; 
 as the needful explanations will also be given in the Notice which 
 follows this one. 
 
 No colour has been appropriated to the hornblende schist; nor 
 could it, though that is a principal rock in the system. In what- 
 ever manner it may exist elsewhere, it occurs in Scotland, with 
 one exception, only as a very inferior stratum, alternating with 
 gneiss most generally, but sometimes also with a numerous set 
 of rocks, including chlorite schist, which I shall describe here- 
 after. Its relation to the gneiss, both in proportion and disposi- 
 tion, is similar to that which the shales bear to the sandstones : 
 and if, in each case equally, these inferior substances could not 
 be distinguished in any manner, so is it the usage not to make 
 
 such distinctions. . . 
 
 The exception to which I alluded, occurs in the mountain ben 
 Lair, near Loch Maree ; and as far as I now know, it is also a 
 solitary or rare occurrence. This tract is nearly all composed of 
 the hornblende schist, to the equal exclusion of the gneiss; but 
 the space which it occupies on the Map is so small that it would 
 have been fruitless to have appropriated a separate colour to it ; 
 as in this case also it would not nave been easy to know where 
 to stop in making the same distinction, while, if pursued, it must 
 have fcen under so outrageous an exaggeration of the extent of 
 this rock, that the result would have proved a greater falsity 
 than the total omission. In the mean time I must trust to the 
 present explanation, and to further ones which will be given 
 hereafter. 
 
 The same reasons apply to octenolite schist, but in a far greater 
 degree ; since it is an extremely rare substance : and, whenever 
 it occurs, is in quantities so very minute, that only a very narrow 
 research can discover it. The only very noticeable bed ot it 
 which I could find, extends from Glen Elg towards Sky, yet is 
 not traceable far without interruption. To describe it accurately, 
 would be easy, though it cannot be represented on the Map; 
 but such description would be the object of that work on Scot- 
 
109 
 
 Geological Map of Scotland. 
 
 land, under the minute and peculiar views of geological science, 
 which if I once intended to give, I have resolved to suppress, for 
 reasons, the force of which will be apparent from some remarks 
 in the Notice respecting the Map. That knowledge which it 
 would be worse than fruitless to make public, must die where it 
 exists. 
 
 If the micaceous schist is delineated under a single colour, 
 there was nothing belonging it that admitted of distinctions : 
 further than I shall immediately have occasion to notice under 
 ehlorite and talc schists, where its intermixtures are chiefly 
 engaged ; since any notice of its varieties was as impossible as 
 to nave noticed those of granite, gneiss, or any other rock simi- 
 larly variable in structure and composition. A work which 
 I have already published on the distinctions and characters of 
 rocks will suffice for this purpose, as it will equally prove the 
 impossibility of making such distinctions on this Map : and with 
 that, he who would desire additionally to understand this sub- 
 ject and to know what the rocks of Scotland are, in all their 
 details, must be content. 
 
 If nearly the same remarks are applicable to quartz rock, 
 equally represented by a single colour, I need not prolong this 
 detail by repeating them. 
 
 I was much more doubtful how to act respecting chlorite 
 schist, but at length resolved not to distinguish it from mica 
 slate in the colouring. The only doubt I entertained related to 
 the ridge of Ben Lawers, where a considerable tract of it occurs, 
 tolerably distinguished from the mica slate for a considerable 
 space. But this notice must suffice respecting a tract which it 
 seemed inexpedient to distinguish, even had it been easy, when 
 so many more of smaller extent must be suppressed for the usual 
 reasons, and when, above all, it was utterly impossible to dis- 
 tinguish the far better defined chlorite slates which occur in 
 what I have called the chlorite series, and those which are inter- 
 mixed with clay slate throughout that singular line which tra- 
 verses Scotland in a north-easterly direction. And since chlorite 
 schist, as it occurs in Scotland, is really very ill distinguished 
 from mica schist, whether in place or mineral composition, while 
 in both ways for ever passing into it, the adoption of the present 
 plan seemed as unavoidable as it was conformable to the usual 
 practices of geology. 
 
 That which I have just termed the chlorite series, now de- 
 mands a special remark. It consists of many different rocks, as 
 I shall notice in another Report ; but these are so numerous and 
 so intermixed, that the substitution of a yard for an inch in the 
 scale would not suffice to represent them. It also constitutes a 
 geological group so new and so peculiar, that it demanded to be 
 distinguished from the neighbouring mica schist with which it is 
 nevertheless always associated, and into which it graduates : for 
 which reason it is indicated by a peculiar colour, though that 
 ought no more to be defined with respect to the colour of the 
 
V 
 
 110 Memoirs to H. M. Treasury respecting the 
 
 mica, schist, than the different substances themselves are in 
 nature. Respecting talc slate, though one of the rocks in the 
 general system, there could be no doubt. It is an extremely 
 rare substance in Scotland 5 and the specimens, rather than 
 strata, of it, which do occur, are exceedingly minute, as they also 
 pass into the neighbouring mica slate. In the place also where 
 this rock is most conspicuous, near Loch Fyne, the far larger 
 portion is so intermediate a substance, as happens also near Loch 
 Tay, that it was quite as justifiable to confound it with the mica 
 slate on the map, as to have given it a separate indicative colour, 
 even had that not been impossible or inexpedient, for the reasons 
 already more than once assigned. 
 
 All the clay slate has been represented by a single colour. 
 Geology had made a gross mistake in distinguishing it into clay 
 slate and graywacke slate ; as I have fully showed in former 
 published works, and need not repeat in this place. I have, in 
 conformity to this correction, represented it as a single rock ^ 
 and though it had been desired to distinguish the coarse kinds 
 from thelfine, this could not have been done, any more than 
 I could have distinguished the varieties of any other rock, so 
 minute and frequent is the intermixture. And even the quarry- 
 men need not be told that workable slate cannot be distinguished 
 from that which is not workable, by any means short of absolute 
 trial : while it was not within my limits to note every quarry in 
 Scotland, any more than every coal-pit and mine; as, if I had 
 even desired this, it could not have been done on this Map. 
 
 If these remarks apply to the slate of Scotland universally, 
 that which occupies the singular north-eastern belt already no- 
 ticed, demands a separate one. I shall hereafter show that it 
 includes a great variety of distinct rocks, many of which also are 
 of a very anomalous character. But since these were undistin- 
 guishable in the Map, as much so indeed as the strata in the 
 chlorite series, and since the predominant rock was clay slate, 
 producing also, in many places, workable slate, it was equally 
 expedient and inevitable to distinguish it by one colour, as has 
 here been done. 
 
 On the primary limestone and the serpentine I need add no 
 remarks here to those made respecting their minuteness, in the 
 Notice respecting the Map ; since they are uniform substances. 
 
 The porphyry requires considerable explanation; and as, on 
 some points, this rock involves the case of the trap rocks also, 
 I must disturb the usual order by here taking these two sub- 
 stances together. 
 
 The joint ignorance and hypothesis of geology has hitherto 
 made pornhyry an utterly distinct rock from those other unstra- 
 tified ones which it confounds under the general term trap. But 
 unless there be some other character united to the porphyritic 
 structure, there is no such distinction in a geological point of 
 view. The porphyritic form and character occur among the 
 latest trap rocks, and the same continuous mass often unites 
 
Geological Map of Scotland. 1 1 x 
 
 this peculiar character vvitli others quite dissimilar ; as, further 
 the porphyritic distribution of the parts is found in many rocks 
 of very different composition and materials. 
 
 It is plain therefore that porphyries like this, or rocks of this 
 character, being of later origin than the secondary strata, and con- 
 nected with the most recent ordinary traps, cannot be distinguished 
 from these, unless we were equally to distinguish in the colour- 
 ing of these Maps, all the modes and varieties of trap, and further, 
 all those of granite, since the same facts apply to both. There 
 is no geological ground for making the distinction ; and it would 
 be mechanically impossible to distinguish the whole, as will im- 
 mediately be shown. 
 
 But if it can be ascertained that there are porphyries connected 
 with the primary rocks alone, and never interferino* with the 
 secondary ones, a division should be made, on the ground of age, 
 and thus there should be a colour for such porphyries, distinct 
 from that vvtiich is applied to the traps. Such porphyries rank 
 with granite, to which they also often approach in character: 
 and if this be not done, then the granites which become green- 
 stones and basalts must also be coloured as traps, and separated 
 froni the other granites, to the utter confusion of all geological 
 distinctions. It is in fact but a portion of the universal geologi- 
 cal question, whether rocks are to be distinguished by their 
 geological characters or their mineral composition; since, if 
 adopted in one case, the principle must be followed in all, while 
 the consequence then would be to confound many more of the 
 rocks of the system, such as quartz rock and the secondary 
 sandstones, shale and clay slate, and much more. 
 
 But admitting this principle, namely, that the age and con- 
 nections, not the mineral character, are to regulate the names of 
 rocks, and therefore that some porphyries must be distin- 
 guished from others, the difficult practical question remains, how 
 this is to be done in every instance. The obvious evidence is 
 that such a porphyry is ancient, or demands a distinction and 
 colour for itself, whenever it interferes with the primary rocks, 
 and does not interfere with the secondary ones : and reversely, 
 that in the latter case it must be referred to the traps. 
 
 But the practical a])plication of this rule is by no means so 
 certain and easy as it appears. Though the secondary strata are 
 absent, it does not thence follow that a given mass of porphyry 
 is of a date higher than that of their production. They may 
 never have existed in that place, or they may have been removed 
 under the usual progress of waste. In the former case, though 
 the porphyry had been of the most recent date, there has been 
 nothing to give evidence of its age ; and, in the latter, that evi- 
 dence has disappeared. Nor do the mineral composition and 
 characters give that evidence which cannot be found in the for- 
 mer circumstances. This indeed has generally been maintained : 
 but I have proved that it is not the fact. 
 
 The general result of this brief discussion therefore is, that we 
 
112 Memoirs to IL M. Treasury resjyecting the 
 
 can obtain no absolute evidence on the date ot a porphyry, from 
 negative circumstances, or from its non-interference with second- 
 ary rocks : though the reverse fact, or the positive knowledge 
 that it does interfere with those, is sufficient to settle its modern 
 nature, and consequently to give it a place with the traps. 
 
 Under these views and difficulties, I must now therefore ex- 
 plain how I have acted in the case of this Map. But though I 
 made the best inferences which I could, I am by no means satis- 
 fied that they are all just : for which reason I must here enume- 
 rate the spots themselves, that they who may examine the work 
 may be more fully informed than they could be by a mere inspec- 
 tion of the colouring. It is scarcely necessary to premise, now, 
 that the colour chosen for the porphyries supposed to be of an- 
 cient date is a purple, as the decidedly modern ones are united 
 to the general traps under the colour of Prussian blue. 
 
 The great mass of porphyry near Loch Fyne sends veins through 
 the mica slate, and is therefore more recent than that rock. But 
 there is no secondary rock so near as to be reached by these 
 veins : whence there was no resource but to view it as an ancient 
 porphyry, though under such negative evidence there can be no 
 certainty. 
 
 Near Kirkcudbright another extensive tract of porphyry sends 
 veins through the slate, but not through the line of sandstone 
 which here skirts the sea shore. For the present it must there- 
 fore stand as an ancient porphyry : but if any one shall here- 
 after find a vein penetrating the sandstone, it will be necessaiy 
 to remove it to the traps. 
 
 A small mass of porphyry in Banffshire must remain as it is 
 noted, for similar reasons ; and so must the great veins noted in 
 Mar, and near Blair Atholl and Loch Rannoch. So must that 
 on the summit of Ben Nevis: respecting which there is no chance 
 of discovering any other connection than the present. 
 
 The porphyritic veins of Glenco, so numerous as to have de- 
 manded a very marked record, have been noted as if they were 
 ancient. There is no evidence to the contrary at present : but 
 the following remarks on the analogous veins of Cruachan, may 
 throw some doubt on a conclusion which I was nevertheless not 
 justified in altering. Every one, including myself, had hitherto 
 believed them to be ancient porphyries, since they traverse gra- 
 nite and mica slate, and also possess that peculiar mineral cha- 
 racter which belongs to those esteemed most ancient. But the 
 neighbouring trap, which covers the red sandstone, is also tra- 
 versed by veins exactly resembling them in characters, number, 
 and magnitude; whence it seems a safe inference that the whole 
 are connected, or that the latter are the prolongations of the 
 former, though the intervention of the deep valley of the Awe, 
 renders it impossible to trace any vein on one side into another 
 on the opposite one. Nevertheless I have coloured, equally, the 
 veins on both sides, with the colour of the ancient porphyry. 
 On the Cruachan side this is probably wrong : on the Tyanuill 
 
Geological Map of Scotland. 113 
 
 side it certainly is. But it was important to record this fact, and 
 there was no other means of representing these veins, at least 
 on the side of the trap, since a blue line would not have shown 
 on a blue ground. The present note will prevent any error. 
 
 Now it must be left to future researches to inquire whether the 
 veins of Glenco are not of the same date. This will be proved 
 if a vein can be traced continuously through Glenco and Crua- 
 chan : though the difficulties are so great, from the distance and 
 the nature of the ground, that it is little likely to be done. In 
 the mean time I have not, myself, been able to do this ; so that 
 the wlwle must remain as it now stands, under the present ex- 
 planations in addition to the coloured record. 
 
 These are all the cases in which I have here represented por- 
 phyry as an ancient rock by giving these places the tint of purple ; 
 if 1 except Campbelltown, including the rock of Devar. In 
 these there commence a set of doubts which prevail widely in 
 the south of Scotland, and which render this explanation in aid 
 of the colours which I have adopted, peculiarly necessary. The 
 porphyry of Campbelltown does not touch the secondary strata, 
 though sometimes quite close to them ; and hitherto I could find 
 no veins penetrating these. Devar, being an island rock, affords 
 no evidence of any kind ; but whatever may finally be concluded 
 of the one will be true of all. In the mean time, the purple 
 must stand : though as a subject for future correction. 
 
 In Raasay, with the sole exception of Duncan hill, the entire 
 mass of the unstratified rock is a porphyry which, as a mineral 
 specimen, would be classed with porphyries, and not with traps ; 
 while they who were ignorant of the ground would also suppose 
 it an ancient one. But it lies above the lias and green sandstone ; 
 so that it was necessary to give it the general colour of the traps, 
 unless it had been possible to have distinguished every variety of 
 these. 
 
 The same reasoning extends to Sky and to Arran : the facts 
 being identical in the former case, and analogous in the latter : 
 while I shall hereafter have occasion to extend these notes so as 
 to give all the aid that can be given by them in enabling the 
 inspectors of this Map to distinguish among the several varieties 
 of trap to which the general tint of blue was compulsorily 
 assigned. 
 
 Whatever other porphyries may occur in other places than 
 those which I am now about to note, coloured as traps in the 
 Map, they are comparatively insignificant in quantity; as it 
 would be equally endless and purposeless to describe the places, 
 since they could scarcely be found, and would produce a long 
 catalogue of names and descriptions difficult to verify on the 
 Map or the ground. It must suffice to state the general fact: 
 and the observer will be sufficiently prepared by these state- 
 ments, whenever they may occur in his researches. 
 
 It is in the line which is marked by Tinto and the Pentland 
 hills that the first very remarkable and extensive masses of por- 
 
114 Memoirs to TL M, Treasury respecting the 
 
 phyry occur, in proceeding towards the southern division and 
 border of Scotland. And they are so very remarkable, and so 
 unlike the ordinary traps, that this annotation is especially 
 necessary : since, for the preceding reasons, they could not have 
 been distinguished by a specific colour. 
 
 I could not specify every place and every change, without a 
 detail of the notes made on this subject, which while it belongs 
 to that scientific geology into which 1 do not mean to enter, 
 would be infinitely tedious, and, for the present limited object, 
 as purposeless as it would be difficult to make use of it in the 
 verification of the ground. But the remarkable fact is, that on 
 this line there occur great tracts or masses of a porphyritic rock, 
 or of an analogous rock without imbedded crystals, which must 
 sometimes be ranked as a compact felspar ; at others as a clink- 
 stone, and at others again, as a hard claystone. And it is also 
 to be noted, that these rocks are very extensively reddish or 
 brown, or of some grey tints very unlike the ordinary dark hues 
 that prevail among the trap rocks. But their date is unquestion- 
 able, because they are more recent than the coal series, as the 
 ordinary blue clay stones and other traps also occur among them : 
 and thence has the single and usual colouring of trap been 
 adopted for them. 
 
 I have been in doubt what to determine respecting the Aildon 
 hills, but have finally entered them under the colouring of all 
 the other traps of the south of Scotland. The present note will 
 at least explain the facts; and he who thinks this particular 
 entry inexpedient, or may discover that it is wrong, can easily 
 obliterate the present colour and substitute the purple. It is 
 true that the rock is far more analogous to, or identical with, 
 those last named than with the more usually esteemed traps, and 
 it is not less true that it lies in slate and does not come into con- 
 tact with secondary strata. But many of the insulated traps of 
 this district touch the slate on one part and the sandstone on 
 another ; so that the removal of this latter portion, to happen 
 undoubtedly at some day, would lead to a false conclusion as to 
 the age of such a mass. It is equally true that the superficial 
 sandstone has often been extensively removed, leaving the evi- 
 dences in detached portions and fragments. There is such a 
 fragment at the edge of the Tweed near the Aildon hills : and it 
 is from these circumstances that the present inference has been 
 drawn. With an explanation of this nature in addition, the 
 mode of entry is of little moment : but others can judge as they 
 think fit. 
 
 The great tract of unstratified rock which extends between 
 the Tweed, the Cheviot and the Carter-fell, and of which, frag- 
 ments, or what seem to be fragments, are widely dispersed 
 along the ridge which includes Fauna hill, presents the last of 
 these difficulties ; while under all the circumstances of the evi- 
 dence, I have concluded to colour it as trap. If some portions of 
 it cover slate onlv, others are connected with the red sandstone, 
 
Geological Map of Scotland. 1J5 
 
 and others again with the sandstone of the coal series which 
 occurs on the Carter-fell. Yet the far greater portion, thoutrh 
 not the whole, consists of rocks similar to those of the Tinto and 
 Pentland range. It is evident indeed in some places, that there 
 is more than one date for the whole, because there are veins of 
 one kind penetrating the masses of another. But unless it could 
 he pioved that all those portions which are connected with the 
 several sandstones were different from those connected with the 
 slate, we could not conclude that there was here a primary and 
 secondary rock both, or a porphyry to be coloured with purple 
 and one to be coloured with blue : while the evidence, as far as it 
 can be found, lies the other way, or proves that the same mass 
 interferes with both, although there are masses of different dates. 
 
 With this statement in addition to the present entry on the 
 Map, there can at least be no error, though doubts may be enter- 
 tained of the truth of the general conclusion as far as the whole 
 tract is concerned. But the opinions one way are of no more 
 value than those on the other side : whence, as in so many other 
 cases, it is a question that must be left to future investigations 
 or casual discoveries : as I shall pay no attention to the sug- 
 gested corrections of those, who, as the great dealers in opinions 
 and hypotheses, are also the worst of observers, and, from every 
 cause, the least to be trusted, though always criticising and cor- 
 recting, with a coiifidence equal to their ignorance, and the 
 surest mark of that ignorance. 
 
 But those fragments which are noted near Fanna hill. Wester- 
 kirk, and elsewhere, are still more likely to be disputed. There 
 is no sandstone near them, or they lie entirely in and on the 
 primary slate. Yet I have coloured them as recent traps, and on 
 these grounds. They are masses nearly worn out, and fast dis- 
 appearing, as, in many places, they are both very narrow and 
 very thin, while in others they are evidently nothing but veins 
 proceeding from a principal mass. Hence that difficulty in 
 finding them under the incumbrance of peat in this obscure and 
 trackless country, which I noticed in the account of the Map, and 
 which convinces me that the delineation here given must be very 
 imperfect. Now if the veins are veins from the great mass 
 already described, they are recent of course, though traversing 
 only primary rocks. And by tracing the first set of these frag- 
 ments from the Carter-fell along the north of Fanna hill, it is 
 almost demonstrable that they are the remains of a continuation 
 of the same great mass once covering this country far more 
 widely : whence I have extended the same general conclusion to 
 those which are situated more remotely and in a more detached 
 manner. The portions marked near Westerkirk are undoubtedly 
 very far separated from the rest ; but if any one does not choose 
 to coincide in the present inference, he can change the tint and 
 adopt his own views. The whole difficulty is a matter of no 
 great moment, even in geological science : since there is abun- 
 dant proof of porphyries of different dates, and since it is the 
 
 I 2 
 
1 10 Memoirs to JL M, Treasury respecting the 
 
 general fact alone which concerns that science : while as a ques- 
 tion of utility or statistics, it is absolutely indiflPerent, inasmuch 
 as the consequences would be exactly the same whether these 
 rocks were primary or secondary, of an old or a recent date^ 
 coloured with purple or coloured with blue. 
 
 The continuation of this explanation, including all else that 
 belongs to these unstratified rocks, relates to those traps which 
 are demonstrably secondary, and which it has been agreed to 
 class under this general term, though so numerous, and so widely 
 differing in character and composition as they do. 
 
 For the distinctions and characters of these I must refer to 
 my own work on Rocks, since that information is not to be found 
 elsewhere ; but I must here give at least their names, as the im- 
 possibility of distinguishing them by colours would not other- 
 wise be appreciated. They are the following : hypersthene rock, 
 augit rock, greenstone, syenite, porphyry, amygdaloid, basalt, 
 clinkstone, two qualities of claystone, and tufo ; to which I must 
 add pitchstone, as being akin to these, or rather a mode of them. 
 And if to these thirteen rocks I were to add that syenite of Sky, 
 which is a true granite in mineral character, though a recent 
 secondary rock, it is plain that it would require fourteen colours- 
 to distinguish the traps alone. 
 
 Now, in this Map, though eighteen colours are entered on the 
 Key, I have not been able to produce more than seventeen alto- 
 gether, that would have been distinguishable on this black 
 engraving, so that the yellow ochre is twice used, and for different 
 rocks. Thirteen others, in addition to the blue used as the 
 colour of trap generally, were therefore unattainable: while, 
 cx)u\d I have adopted two or three, or any number much less 
 than the whole, it would have even more misled the reader, 
 under a more deceptive statement, than in thus generalizing the 
 whole. It is further true, that though some of these specific 
 rocks, in some places, might have been defined, from their marked 
 characters and the large spaces which they occupy, it would have 
 been far otherwise as" to the whole. The porphyry of Raasay 
 might have been thus distinguished, as might the hypersthene 
 rock of Sky and Airdnamurchan, the augit rock of that island and 
 of Rum, the syenite of Ailsa, and more : but in the far larger por- 
 tions of all this extensive body of trap, pervading so much of 
 Scotland, if in separate divisions and fragments, such distinctions 
 would have been utterly impracticable, from the frequent and 
 often minute intermixtures of the different kinds. I must here 
 remark however, that I did make and enter these several dis- 
 tinctions in the surveys and memorials whence the general Map 
 was reduced and constructed in these parts, by adopting separate 
 draughts of the geography on a larger scale, and applying 
 separate keys and sykems of colouring. In this independent 
 manner there was no difficulty : and examples will be found in 
 the published maps of my work on the Western Islands, where 
 separate keys are used for each, and where there was thus neither 
 
Geological Map of Scotland, 117 
 
 want of space nor of colours. But, as I have already said, the 
 entire Map as it now stands, did not admit of this, and thus was 
 1 compelled to adopt the present general expression, in the blue 
 applied to the whole of these rocks : since there would be no 
 limit to the separate publication of the hundreds of enlarged 
 maps of separate tracts which would be required, if the reverse 
 system of such enlarged and multiplied parts of maps had been 
 adopted, and if all which demanded this enlargement and detail 
 not less than the trap rocks, had been included in that plan. 
 
 To a certain extent therefore, this explanation will suffice to 
 show under what light the blue colour adopted for trap must be 
 viewed. In the future remarks on the rocks of Scotland, I shall 
 specify the most conspicuous places where the principal varieties 
 occur; and thus will the geologist be furnished with all the ad- 
 ditional information on this specific subject which the plan of 
 these Reports admits. 
 
 The expression used for the red standstone may be deemed to 
 require some remarks of a similar nature to those passed on the 
 simpler cases which preceded this of the traps. Geologists in- 
 deed will not require this, since they have agreed respecting this 
 rock, as designated by position, be its mineral characters what 
 they may. But they who may regard the mineral characters 
 alone, and they especially who may view this rock as an object 
 of use, would nave wished for distinctions which, for all the same 
 reasons, it was impossible to make on a map of this nature ; such 
 and so intricate are its variations, so numerous are its varieties, 
 and so impossible was it to distinguish these by any mode of 
 colouring. A few general remarks here, added to those which 
 will be found in the general view of the rocks of Scotland, will 
 do all as to this subject which is necessary or possible. 
 
 There would have been no end to an attempt to distinguish 
 the conglomerates from the finer sandstones, and still more would 
 it have been impossible to have distinguished the endless varie- 
 ties of those. If their places had always been the lowest, or the 
 nearest to the primary rocks, that might have been compara- 
 tively possible : but this is not the fact, since they occur in many 
 other ways, as near Stonehaven for example, conspicuously, and 
 since the fine sandstones often occupy the places where the con- 
 glomerates would have been expected, while they are also inter- 
 mixed in many ways and in minute portions. 
 
 In Shetland, and elsewhere, this sandstone cannot be distin- 
 guished as a specimen, from quartz rock ; as this also happens 
 over very extensive spaces ; while its colours are frequently 
 white or dark grey instead of red. It is a very different rock 
 for purposes of economy ; but it is the same geological rock, and 
 as such it must be coloured. If it thus also varies from its 
 nominal colour in many places, and very remarkably in Perth- 
 shire and Forfarshire, while there also becoming a peculiar object 
 in the views of a quarryman and an architect, still there is no 
 resource but to follow the general rule. 
 
 I 3 
 
118 Memoirs to IL M. Treasury respecting the 
 
 In this latter county in particular, there is a still more remark- 
 able and important variation. The shale which geology consi- 
 ders as but a part of the same rock, and classes with it under 
 one term, predominates so much in some places, as near Forfar 
 itself, that, as a separate substance, the rock is truly a shale and 
 not a sandstone ; as there are many varieties connected with this, 
 being flaggy sandstones. It is easy for a separate, or a county 
 map, to make this distinction, because it will possess room and 
 resources in colouring ; and a map of this nature ou^ht to make 
 this and every other distinction, already and hereafter noticed, 
 which I was compelled to pass over ; because this is the very 
 duty of such maps, and because it is here that such statistical 
 and economical details will be sought, as they ought to be 
 found. 
 
 But if even this more remarkable variation was incapable of 
 being specified in the present place, in this particular spot and 
 in some others, I have departed from the usual proceedings of 
 geology in doing this for Caithness ; though in but a general 
 manner; as being the only thing which the obscurity of this 
 deeply covered county permitted. The shale of this district, 
 connected with the red sandstone, forms whole tracts without any 
 intermixture of the latter rock, so that it not only admitted of 
 distinction, but seemed absolutely to require it ; and thence the 
 places of the former are represented in the best admissible 
 manner. If in certain parts of this tract or county, the record is 
 not so accurately true as could be wished, it is because the rocks 
 are not so perfectly distinguished in some parts as in others. If 
 in some places nothing but red sandstone is visible, in othep 
 there is nothing but shale : but, in many, they are intermixed in 
 a manner that cannot be accurately known anywhere except on 
 the sea shores, from the immense spaces covered with a peat so 
 deep as to render every thing equally invisible and unconjectur- 
 able. The rule which I have therefore followed, is to lay down 
 as shale all those tracts where it appeared to be predominant, as 
 well as sole : while I have done the same as to the sandstone : 
 whence it is plain, that in this county, when practically and 
 accurately examined, shale will often occur where sandstone has 
 been denoted ; and the reverse. 
 
 The coal series, as laid down in this Map, demands similar 
 remarks, even more imperiously, from its economical importance, 
 and from the limited manner in which the coal occurs in it. 
 Geology has long ago defined it, collecting many things, namely, 
 sandstones, shales, clays, including ironstones, and limestones 
 more rarely, together with beds of coal, into a single series, or 
 
 formation.’" And thus it lays down with one colour what it 
 defines, as indeed it could not easily act otherwise. Of course 
 1 have conformed to the usage, nor could I have departed from 
 it had I wished to do so. But it does not follow that there is 
 coal present in every portion of such a series ; while nothing can 
 he much more uncertain and irregular than the presence of the 
 
119 
 
 Geological Map of Scotland. 
 
 substance which constitutes the chief importance of this series, 
 whether in the places of these beds, or in their numbers and 
 repetitions. It is moreover true, that the places of such coal can 
 never be known but by experience. It may be traced at the 
 surface, but the traces are commonly very limited : it is only 
 after being investigated by actual mining beneath ground, that 
 it can be estimated and assigned. But if, in England and Wales, 
 very generally, it can thus be assigned very widely, that is not 
 nearly so true of Scotland, where the coal field, or fields, are so 
 separated and disarranged by trap rocks, that calculations to a 
 similar extent, from partial knowledge of the workings under 
 ground, cannot be safely made. 
 
 Now it is plain, that in as far as the very limitations of a geo- 
 logical Map are, to lay down the rocks at the surface, it could 
 not notice the coal itself as a distinct object in that series ; since 
 the very small quantities visible at the surface would not form 
 more than a few microscopic points on the Map. And as no 
 reasonable conjectures respecting its existence beneath could be 
 formed at any places where it was not actually known, not even 
 a conjectural inference could be recorded: so that the whole 
 series was laid down, as I have just said, under the ordinary 
 usage and in one colour. At the commencement indeed of these 
 examinations, I attempted to denote, by some marks, the places 
 where coal was actually wrought. But finding, first that the 
 geography was too incorrect to admit of the places of coal-pits 
 being truly entered, and seeing that falsity of position must be 
 the frequent consequence of such an attempt, while these marks 
 would have been invisible on so much of the Map, without such 
 exaggeration as would have confused the records of the rest, and 
 especially of the trap rocks in which the coal is so often en- 
 tangled, I was obliged to expunge what was done, and abandon 
 this design. And on reflection it appeared as superfluous as it 
 was impossible. There is no secret respecting these things, as it 
 requires no geologist to discover them. Every person knows 
 where they are in his own neighbourhood, and it is for that 
 neighbourhood that he will chiefly consult this Map : while the 
 future geological surveyors of tracts or counties will find no 
 difficulty in entering them in their proper places, as it will be 
 their object to do so. And even to have given a verbal list 
 of these places, here, would have been to do imperfectly 
 what is better sought in Mr. Bald’s printed accounts of this 
 subject. 
 
 It is lastly true of this series in Scotland, that it is believed to 
 contain conspicuous limestones independent of the mountain 
 limestone beneath it. It will be for future observers, versed in 
 geology as well as in coal mining, to determine what the value 
 of this authority is, or, what will be really necessary, to deter- 
 mine the facts by a proper examination of all these reported 
 spots. My time did not admit of such minute, and generally 
 
 I 4 
 
120 
 
 Memoirs to H. M. Treasury respecting the 
 
 underground examinations, for such a purpose : but from what 
 I was enabled to see, I had reasons to doubt the conclusions of 
 those coal-viewers, finding that such as 1 could examine were 
 referable to the mountain limestone, and perceiving that the 
 assertion in question had sometimes arisen from not duly esti- 
 mating the extraordinary disturbances of these strata produced 
 by the frequent vicinity of trap. 
 
 Future and more minute knowledge will correct the general 
 entry which I have made of all these limestones, should I in any 
 instance prove to be wrong : but it will be even then but a ques- 
 tion of geological science, since the economical object will be 
 as well accomplished in the present way as in any other. Every 
 secondary limestone connected with the coal series has been laid 
 down as the mountain limestone, with a single colour : while, of 
 the far greater number at least, I ought not to doubt the correct- 
 ness of this determination, partly from their positions, and partly 
 because they include those fossil shells, which are considered 
 among the distinguishing characters of this rock. 
 
 But I have also done this where no coal strata are present, 
 and even where the limestone is decidedly subjacent to some of 
 the red sandstone strata, if not to all ; as in others it at least 
 appears to be so. I know not that it is worth while for geology 
 to distinguish between the separate and great beds of lime 
 occurring above the red sandstone, and the smaller ones which 
 occur in it, since it is but a fact analogous to many more in 
 these associations of stratified rocks. And being so, these 
 beds are parts of the mountain limestone : while of some of the 
 instances thus represented on the Map, it is true that they pre- 
 sent the same evidence in the identity of the fossil shells con- 
 tained, be the value of that evidence as perfect as it has been 
 esteemed, or otherwise. But the Map itself will at least show 
 where these cases are : so that any one who may not be satisfied 
 can re-examine them. At any rate, I should scarcely have given 
 them a separate colour, though I had thought otherwise : since 
 the distinction is a trifling one, and the economical purposes 
 are equally well served on the present plan. 
 
 I need not separate the lias, the oolithe, and the greensand, 
 in the consideration of the expressions which I have been obliged 
 to use for those in this Map ; while the lignite coal occasionally 
 included will equally find its place in these remarks. 
 
 With scarcely other exceptions than those of Sutherland and 
 Campbelltown, the fragments of these limestones are so small 
 that they could not be represented on the Map without exagge- 
 ration, as I elsewhere noticed. And this is equally true of the 
 green sandstone; with the still inferior exceptions of Raasay, 
 Strathaird in Sky, and Inch Kenneth. If I have therefore 
 noticed this rock by the same colour as the coal series, for want 
 of another, yet showing that it can be distinguished, because it 
 is then attended, in contact, or near at hand, by the colour for 
 
lias, I have been compelled to omit it in some other cases, be- 
 cause its colour could not have been introduced without disturb- 
 ing the others. 
 
 But I found it as impossible to separate the lias and the 
 oolithe, as it was to find colours for the two, that should be visible 
 in such minute spaces ; while, on the former grounds, no notice 
 is taken of the actual existence of coal. Nor can this be of any 
 moment. These two limestones may almost safely be united into 
 one series ; and if it were not so, there would be no remedy in 
 the present case. In some parts there is lias without oolithe, as 
 there are limestones with the green sandstone and without it ; <in 
 others there seems to be oolithe without lias; and in others 
 again, nothing more than the shale belonging to one or other or 
 both of these rocks. Such is the joint effect of the minuteness 
 and dispersion of these fragments, and of the action of the trap 
 rocks on them. One general expression for the whole was there- 
 fore indispensable, while it has been extended even to the merest 
 fragments of shale, as in the Shiant isles, that the very singular 
 dispersion, and therefore original connexion of this deposit, might 
 be visible, under the interest which geology may feel in this fact, 
 but in which economical statistics can take no share. 
 
 As to any thing else which geology may require respecting 
 this strata, it may be sought in the additional Notice explanatory 
 of the rocks of Scotland. 
 
 Of diallage rock I need say nothing, further than that I was 
 compelled to omit, on the Map, some fragments of strata, if 
 they can even be called such, not amounting to a yard in di- 
 mensions in any case, which occur in a few places, accompanying 
 serpentine, as usual; but which are in g€ ' 
 minute that they might rather be considere( 
 nerals than portions of rocks requiring geolo; 
 
 Pitchstone, as a separate rock, could nc 
 noticeable on the Map, since, with exception 
 if that rock ought to be thus ranked, it occur 
 only, and in a very few places : limited, as 
 to Arran, to Eig, and to Sky, while, in the t\ 
 only very small points. Nor, if practicable, 
 sary, when this rock is safely ranked with th 
 
 I have discovered that compact felspar is 
 rock, not connected with any formation of tn 
 with gneiss. But the quantity is, any where 
 I could not notice it by any colour : while 
 of the larger masses occurs, any attempt to 
 confused the whole island. If the limest 
 omitted in this island, I know not that I oug 
 that, of which nothing but the place remains. 
 
 I have noted j asper, chert, and silicious sch 
 in the system which I formerly drew up, a 
 their characters, relations, and origin. One 
 these, are of perpetual occurrence wherever 
 
 L 
 
 
V 
 
 122 Memoirs to H. M. Treasury respecting the 
 
 shales, or limestones occur near granite or near the trap rocks : 
 since to the influence of these on the several strata they owe 
 their origins. In almost every case, not one of these could have 
 been represented on the Map, since their limitations are to within 
 a few feet of the contact, even had there been colours remaining 
 to do all this. I might indeed have represented the hard slates 
 which often assume this character very perfectly, in Galloway 
 and elsewhere : but it did not seem essential to distinguish them 
 from the general mass to which they belong, as indeed I could 
 have found no expedient to do this, from the same ever-recurring 
 cause, the want of adequate colours. 
 
 But the whole of these facts have been made known to geolo- 
 gists, generally, in my own writings, as many of the examples 
 have been pointed out. They now know where to seek them 
 and how to account for them ; and as no economical purpose 
 could, as far as I can foresee, be served by such a record on 
 the Map, this compulsory omission will be of the less moment. 
 I must only notice here, that there is near that house named the 
 Burn in Forfarshire, a mass of jasper lying in the slate, which 
 ought to be distinguished in this place, but could not be noted 
 in the Map : because of its small extent, and as it is of a nature 
 susceptible of ornamental uses; which, as far as I have seen, is 
 not the case any where else in Scotland. The jasper of Dunbar, 
 with some analogous ones in other places, lying in sandstone, 
 and converted from it, is a geological curiosity, but could not 
 have been entered on the Map. 
 
 The deposits or strata of clays in England are of sufficient in- 
 terest and conspicuity to have demanded an entry among the 
 other strata of this part of the Island. There is nothing of this 
 nature in Scotland, as far as my observations could make out : 
 with perhaps that exception of the place in Caithness where 
 fishes occur in marly slate, and of which I have already declared 
 my ignorance, and the reasons for it. 
 
 All the clays which I know in Scotland are to be ranked under 
 the following heads ; and as such, the plan of this Map, and my 
 own views as to these facts, did not either demand or permit a 
 coloured record. 
 
 The traps and the granites, and more rarely the gneiss, are 
 often so widely and deeply decomposed as to form great bodies 
 of clays, of different characters ; and this occurs most widely 
 I think, in Aberdeenshire as to the latter, and in Sky as to the 
 former. They are all coloured in this Map, together with the 
 rocks from which they derive. And the same is true of the slates. 
 When these clays occur beneath the same rocks, as is sometimes 
 the case, it is still more plain that the Map ought not to have 
 distinguished them, if even that were possible. 
 
 I elsewhere remarked that immense spaces over the red sand- 
 stone and the coal series are often covered with alluvia, which are 
 clays of diflerent kinds, to an enormous depth. This is not less 
 true of the trap rocks. Entire masses have evidently disap- 
 
12a 
 
 Geological Map of Scotland. 
 
 peared ; and in these spaces we find great beds of clay which are 
 their produce, as is very often proved by imbedded nodules that 
 have not yet undergone entire decomposition. It is plain that 
 the attempt to represent any one of all these several clays would 
 have been to abandon the representation of the subjacent rocks, 
 as it would have been an easy expedient well understood by the 
 constructors of some geological maps, to get rid of the difficul- 
 ties of investigating tnese most difficult portions of Scotland. 
 Whatever of this nature may be required must be left to a map 
 of the soils, not of the rocks of Scotland : and it may perhaps 
 occupy hereafter the joint knowledge and labour of an agricul- 
 turist and a geologist. 
 
 The clays of the coal strata are as necessarily represented 
 under the geological hieroglyphic of that rock as the shales of 
 the same series, nor do I know that they are any where sepa- 
 rately distinguishable at the surface, beyond veiy small spaces. 
 
 The remaining clays are the alluvial deposits of rivers, or of 
 rivers and the sea conjointly, or of lakes that have been drained 
 or filled. Viewed as mere alluvia I have already assigned rea- 
 sons for not recording these, to the obscuration of the rocks be- 
 neath. It is true, that in such tracts as the Carse of Gowrie 
 and that of Stirling most conspicuously, some geologists might 
 choose to arrange these with their fresh-water formations, under 
 the usual confusion which they have hitherto continued to make 
 on this subject. But under such a rule as this, every flat part 
 of every coast which has repelled the sea is equally a fresh-water 
 formation, and would claim, not only a separate distinction and 
 colour, but separate sets of colours to denote each deposit of 
 clay, sand, marl, and so forth. But neither would my geologi- 
 cal views allow me to adopt such a system as this, nor could I 
 consent to extinguish such large tracts of rock from the Map of 
 Scotland. All such alluvia are therefore unnoticed ; and the 
 subjacent rock, as determinable by the best procurable evidence, 
 is substituted for such blanks as this practice would produce. 
 In any view, a record of such alluvia would be a map of soils, 
 not of rocks ; and to some such future map must entries of this 
 nature be trusted. 
 
 The sands of Scotland demand the same kind of remarks, al- 
 though they occur in some places very conspicuously. They are 
 deposits by rivers, or by the winds, or are the produce of de- 
 composed rocks. Tirey is nearly all formed of blown sand, and 
 there are extensive tracts of it in the outward chain of the Western 
 Islands, as also in Coll, and on the shores of Moray, Fife, 
 Sutherland, and Aberdeenshire. In the whole of these I have 
 omitted the sand, and represented the subjacent rocks. At Kil- 
 drummie and elsewhere, the sandstone rock has become sand by 
 decomposition : I have acted in this case as with the clays pro- 
 duced in the same manner. The alluvial sandy tracts formed by 
 rivers admit of the same remarks as those already made on the 
 similar clays. 
 
124 Memoirs to H. M. Treasury respecting the 
 
 I have been obliged to follow the same rule as to the filled, or 
 partially diminished lakes ; though these are often economically 
 remarkable for containing beds of marl, as is the case with 
 Restennet and many more. It is the idle question of misarranged 
 fresh-water formations, once more. There is not a lake in Scot- 
 land which has not such a “ fresh-water formation” as Restennet 
 moss, on some part of its margins ; that of Loch Tumel is of 
 great extent. All the great flat peat bogs, such as Locher moss 
 and the moss of Inverlochy, come under the same head, and there 
 is scarcely a flat bog in the Highlands which has not been a 
 lake; or at least has not contained one; while beds of shell 
 marl, as well as clays and sands, are found in most of these, 
 whenever they come to be excavated ; though in every case, ex- 
 cepting that of Restennet, where the circumstances were such 
 that the presence of the marl could not have been overlooked, 
 the discovery of these marls has been a matter of pure chance. 
 A remarkable instance of this nature occurs at Auchtergaven, 
 between Perth and Dunkeld, where a tract, once almost utterly 
 worthless, has been converted into a valuable estate by the chance 
 which, in removing the peat for use, displayed the subjacent bed 
 of marl. 
 
 This subject is so important in an agricultural view, especially 
 in a tract so deflcient in limestone as is the far larger portion of 
 the Highlands, where also calcareous manure is of great value, 
 and must generally be transported, both by sea and land, at a 
 great expense, that I must be excused for offering some further 
 remarks on it ; though somewhat misplaced in a Meinoir which 
 is not an economical one, but only a needful explanation of the 
 system and the restrictions under which the details of the coloured 
 Map have been regulated. 
 
 A very little observation, united to much less knowledge than 
 that which geologists claim as their own, has taught, or may 
 teach, every farmer, or every peat-digger and roadmaker, in such 
 a country as the hilly portion of Scotland, that if the sea is 
 repelled, and the land extended, near the zestuaries of rivers 
 which terminate in the ocean, the same is true wherever that ter- 
 mination is in an interior or fresh-water lake, be the dimensions 
 of that lake and the size of the entering streams what they may. 
 In the larger lakes, such as that of Tumel, already quoted, in 
 Loch Lomond, Loch Maree, and others beyond enumeration, the 
 flat tracts, first commencing as subaqueous banks, then becom- 
 ing marshes, and finally peat bogs, or meadows, which occur at 
 the entrance of the main stream, are known to every one ; while 
 not less obvious are those lateral flats, proceeding in the same 
 course, which attend the entrances of the smaller subsidiary 
 streams. In a similar way, it can scarcely have escaped any 
 one’s observation, that a single original lake has thus been sepa- 
 rated into two ; of which, in Scotland, I may quote the case of 
 the lakes Rannoch and Tumel. 
 
 Now that which occurs on this great scale, and is so very 
 
125 
 
 Geological Map of Scotland. 
 
 obvious, takes place also on a much smaller, and even on a very 
 minute one, where it is by no means so easy of observation, and, 
 under the predominant circumstances, is very easily overlooked. 
 This is especially the case when the whole operation has been 
 terminated: when the lake has been obliterated, and when a 
 tract of flat peat generally, but sometimes of meadow land, still 
 gives passage to the stream by which this work of extending the 
 terrestrial surface was effected. If geologists have overlooked 
 this, it is not surprising that it should have remained unnoticed 
 by the neighbouring agriculturists; of which also, the far 
 greater number, in those parts of Scotland to which I here 
 allude, are without education, however acute they may be, and 
 are also restrained to daily and limited labour by their poverty. 
 The disappearance of such a lake as Loch Ore could scarcely be 
 overlooked, from the nature of the present ground, even were 
 the recollection of its recent and artificial drainage obliterated ; 
 but it is not always easy to trace the similar ancient state of a 
 ta’act respecting which there is neither recollection nor tradition, 
 whether the change has been the result of a natural drainage 
 under the deepening action of the issuing stream, or the deposi- 
 tion of alluvia by the entering one, or by both united. 
 
 But that which is sufficiently difficult, even in such a case as 
 that of Auchtergaven, above-mentioned, becomes far more so in 
 those cases where the original lake has been very small, or 
 where even the term lake is scarcely applicable ; such collections 
 of water deserving no better name than that of pools. The wes- 
 tern shore of Sutherland still abounds in such pools, of every 
 imaginable dimensions; and I here quote them in illustration of 
 what many other parts of the Highlands, and indeed of every 
 mountainous tract in Scotland, must have been in former times. 
 
 Now it is in such obliterated pools, as well as lakes, that marl 
 will be found ; not always, possibly, but very widely and gene- 
 rally, as I have proved in several places. The shell fishes of 
 fresh waters have inhabited them in former days, and their re- 
 mains are the marl in question. This fact I have pointed out, on 
 several occasions, to the farmers in the neighbourhood of such 
 places : but, in spite of such examples as those of Restennet and 
 Auchtergaven, with no better success than usually attends the 
 first efforts to introduce new practices ; of whatever value the 
 possession of a calcareous manure might be, and whatever sav- 
 ing might have followed from substituting such manure for trans- 
 ported lime. 
 
 In other writings, I have also desired to teach those who are 
 interested, how conjectures may be formed of the places where 
 such beds of marl ought to exist, sufficient to justify the very 
 small expense that would attend an excavation in search of 
 them, though that should fail of success ; as, with due care in 
 the selection of a right spot, could not very often happen, unless 
 indeed the former existence of shell fishes in such waters should 
 be much more rare than is generally supposed. As to the ex- 
 
12G Memoirs to II. M. Treasury respecting the 
 
 pense indeed, even in case of failure, I scarceljr know how it 
 could occur, unless the places were very distant Iroin the farms, 
 or habitations of the people. Since peat must be raised for fuel, 
 it may as well be procured in such places as elsewhere ] so that, 
 except in the case just named, the labour of trial will pay its 
 own expenses, at the very least. 
 
 But it seems incumbent on me to notice some facts with re- 
 spect to the usual digging of peat ; as the correction of the com- 
 mon practice is essential to the expected discovery of what may 
 exist beneath it. In a notice of this nature, a detail so irrele- 
 vant to the primary object of this Memoir will be excused; as 
 the neglect of it might neutralize all the other suggestions here 
 offered. 
 
 In many places, the mass of peat is so deep, while the quan- 
 tity accessible at the surface is so great, that there is no induce- 
 ment to work down to the bottom of the stratum, whatever may 
 be the case where the beds are thinner and of less extent. In addi- 
 tion to this, it is an economical practice, very usual, and founded 
 on sound principles, not to remove the entire stratum, and, fur- 
 ther, to replace the turf of the original surface on the new and 
 bared one ; that a progressive growth of the same plants may 
 take place, with a continuous increase of the peat stratum, or a 
 replacement, for future, if distant uses, of that which has been 
 taken away. 
 
 Another cause leads to the same practices. This is, the accu- 
 mulation of water in the pits formed by the workings. It is not 
 worth while to be at the labour of draining these, when the ob- 
 ject in view can be attained by continuing to work along the 
 surface : and if ever such strata are wrought to the bottom, it is 
 where the form of the ground admits of a natural drainage. 
 
 Now these are the very places where marl is not to be expected, 
 because such tracts of peat have been produced on declivities, 
 or at least have not replaced the situations of lakes. It is in 
 those very spots where lakes have been, or are likely to have 
 existed, that the natural drainage of an excavation cannot be 
 expected ; as it is therefore in those that the peat is seldom if 
 ever wrought out, or down to the terrestrial soil. But, in addi- 
 tion to this, and to the causes above stated, it is the usual, I should 
 say the universal practice, to cease when the earthy soil has been 
 reached, supposing the circumstances favourable, and the inten- 
 tion to remove the whole stratum, existing. Nor is this unrea- 
 sonable, when peat is the only object desired, and when no further 
 gain is expected from continuing the excavation. 
 
 But although marl may be present in such places, it does not 
 follow that it will lie immediately in contact with the peat, and 
 thus make its appearance as soon as this is removed. All such 
 waters, be they lakes or pools, are subject to the influx of the 
 overswelled streams, which bring down clay, sand, and gravel, 
 so as often to form a new bottom in a very short space, and thus 
 to cover a bed of shells, should such be present : a fact of which 
 
Geological Map of Scotland. 127 
 
 tliere is abundant evidence in tlie frequent alternations of strata 
 of such earthy substances with shell marl. I'hence arises the 
 necessity, should the search after such marl be intended, to 
 continue the excavation into the earthy soil, until satisfactory 
 evidence of its absence be attained : a work of very small labour, 
 since deposits of this nature can never be very deep. 
 
 I may lastly repeat what I have elsewhere written on this sub- 
 ject for the information of agriculturists ; since it cannot, or ought 
 not to be, required by the most minute geologist ; and it relates 
 to the indications of the probable existence of former lakes or 
 pools, where the surface is at present a solid mass of peat, or of 
 peat covered with soil. 
 
 A tract of this nature which is of a perfect level, may always 
 be suspected ; and when connected with an existing lake, can 
 admit of no doubt. If there is no connected water, the same in- 
 ference may be drawn if there should be water in the vicinity, 
 separated from it by a prolongation, more or less perfect, of 
 similar land. But the case of minute or small masses of water 
 formerly existing, where all around is now dry, is a more difficult 
 one ; while drained pools of this nature, whether containing marl 
 or not, abound all over the mountainous parts of Scotland. He 
 who can examine Loch Spey as it now is, will easily see what it 
 will hereafter be ; and thus perhaps form a better notion respect- 
 ing the marks of a former and obliterated lake, or pool, than 
 from a suggestion like the present. But if there be a tract of 
 peat, be it large or small, which is of a water level, and occupies 
 a basin, it may be suspected to be the place of a former pool ; 
 and that suspicion will be rendered a certainty, if it still gives 
 passage to a stream. Such a tract, having a rocky boundary, 
 or a hilly one, on most of its circumference, will be a still more 
 obvious one to ordinary observers : and thus, with a little atten- 
 tion to the suspected ground and to the circumstances of existing 
 pools and lakes, be a guide within the reach of almost every 
 one who may be interested in such a search. I need not prolong 
 this economical notice ; but I will not terminate it, and, with it, 
 the Memoir to which it is, thus, somewhat irregularly appended, 
 without repeating at more length, remarks which I have been 
 compelled to make elsewhere. 
 
 If so remarkable and so often discussed a case as that of 
 Restennet should be admitted into this Map, as should equally 
 that of Caithness had I known where to place it, and on the 
 ground that these have acquired the imposing modern name of 
 fresh-water formations (one of the magical terms of the day), then 
 must I have equally reserved a space and colour for every analo- 
 gous deposit, on the shores of all the seas of Scotland, on the 
 margins of every lake, on the borders of many rivers, and in 
 places innumerable over every mountainous portion of this 
 country, as well as in many parts of the flat interior districts : 
 while, if noticing them only in as far as they were marls, so must 
 I have indicated, and, in justice, under a separate colour, those 
 
128 Memoirs to II. M. Treasury respecting the 
 
 terrestrial marls formed of land shells actually existing, which I 
 have discovered in different places. 
 
 But, to have done this, would have deformed the Map with 
 hundreds of spots of colour, unconnected by any common bearing, 
 and often so minute as to be almost invisible, without great ex- 
 aggeration of space, and further, to have defied the utmost care 
 of the copiers. Nor would this be the only evil ; since whatever 
 was thus noted would have excluded any record of the subjacent 
 rocks, and, still further, have so broken up their connexions on 
 the Map, as often to have destroyed all the geological inferences, 
 or even to have produced a patch-work surface, so dazzling as 
 to have rendered it a chaos of unintelligible colours. 
 
 That a map of this nature would however be desirable, I am 
 not about to question ; but whenever it shall be executed, it 
 would demand a separate record. It is true that I might have 
 done much towards it, but by no means all ; since it would have 
 demanded a separate set of entries and a distinct work, as it 
 would also have called for an investigation very different from 
 that of the rocks themselves, which also was, at no time, within 
 my plan or the limit of my orders, especially during the first 
 portions and years of this survey. 
 
 But if I thus consider its execution as desirable, I know that 
 it can never be done by one man, nor, to any purpose, on a map 
 of this scale and structure, were that even more perfect than it is. 
 Such a record ought to be the work of many men, and of men, 
 as I have elsewhere suggested, uniting agricultural with geolo- 
 gical knowledge. It might be done on county maps, pd on 
 those it ought to be done ; while, whenever executed, it must 
 needs be a work of time. How far a record of alluvia, be their 
 nature what it may, could be united to one of the agricultural 
 soils, on a common basis, I need not here inquire ; while be- 
 lieving that each would demand a separate map ; though, on one 
 or the other, there might also be noted, as an object of pecuniary 
 economy, the useful, existent, or probable, quarries or quarriable 
 rocks, be those limestone, sandstone, granite, or aught else, the 
 coal beds as far as they have been traced in the coal series, the 
 places of the actual workings of these beds, and the situations, 
 recorded or known, of mines, or of metallic minerals holding out 
 the prospect of future mining operations. 
 
(reolo(jical Map of Scotland , 
 
 
 NOTICE 
 
 RESPECTING THE 
 
 MINES AND METALLIC MINERALS OF SCOTLAND. 
 
 IN most countries, that popular opinion which may safely be 
 considered a vulgar one, attaches the chief interest which it may 
 take in a geological survey, to the record or the discovery of 
 mines ; or to that of metallic minerals, under the expectation of 
 future undertakings of the same nature, and future profit. In 
 mining districts, this is not unnatural; but a similar prejudice, 
 with similar anxiety, is very general in countries where few or no 
 mines have ever been wrought, and especially in mountainous 
 ones ; being those with which the notions of the presence of 
 metals are very widely connected. 
 
 This at least has been very generally the case, with even the 
 better educated; though now much less prevalent, under the 
 greater diffusion of scientific knowledge, under greater experi- 
 ence of deception and imposture, and under j uster views of the 
 real wealth of a territory, and of the most profitable application 
 of capital and labour. 
 
 But independently of any views of this latter nature, it must 
 be recollected, as it is now I presume, obvious to most educated 
 persons, though but moderately imbued with science, that even 
 on purely geological and mineralogical considerations, to trace 
 and assign metallic veins forms but a very small part of the inte- 
 rest belonging to such a survey, or of the pursuits demanded 
 from a surveyor under this subject. As far as geological science 
 is concerned, the history of metallic veins, obscure though it yet 
 be, and desirable as it would be to understand that which has 
 hitherto eluded all theory, forms but a small portion of what is 
 expected and demanded from geology and mineralogy. And 
 though, under questions of statistics and economy, or of utility, 
 the knowledge and assignment of metallic veins, or of such 
 minerals as may lead to the working of mines of this description, 
 is of high importance, it must be recollected that it forms but a 
 certain portion of all that to which minerals or rocks are subser- 
 vient for the purposes of life; though the predominant ignorance 
 respecting geology has hitherto been unaware of the liglit which 
 it might throw on the knowledge of the several non-metallic sub- 
 stances used for the purposes of life, and of the assistance which 
 it might afford to their discoveiy, selection, and application. 
 
1?0 Memoirs to H. M. Treasury respecting the 
 
 It ought also not be forgotten, that if the determination of me- 
 tallic minerals or veins, the research after possible mines, or the 
 further investigation of known ones, were the only objects in 
 view in the geological investigation of countries, there are many 
 tracts in every country, and even vast territories every where, 
 that w^ould present no geological interest whatever, and would 
 therefore demand no examination, and deserve no record : as, in 
 any case, every record beyond that of metallic appearances would 
 be superfluous. Thus, if even a survey of this nature, proceed- 
 ing on the hopes of such discoveries, could be defended, the 
 record of it would be w^orthless, for all purposes of utility at 
 least. 
 
 This would be to abandon the whole subject, unless in as far 
 as philosophical geology is concerned ; but if it is true that there 
 is an extensive interest, not as to science, but to public economy, 
 implicated in the statistics of the naked and fundamental earth, 
 in the knowledge of the rocks of a country, and, above all, in our 
 own, to that of the coal series, more valuable by far than the 
 metallic minerals of any country have ever proved, so must it 
 be recollected that the fundamental proceeding, even as to the 
 investigation of metallic minerals, in a country previously un- 
 known, most especially, consists in ascertaining the places and 
 natures of the several rocks of which it is constituted. Geology 
 has discovered that there are certain rocks in w'hich metals may 
 occur again, because they have previously occurred, that what is 
 productive of metallic veins in one country, or in one portion of 
 any tract, may be the same in another : as it equally concludes 
 from experience, that there are certain others, the nature and 
 position of which it can always determine, in which it is in vain 
 to seek for them or expect them, since they have never been 
 found in such associations and positions. Hence the assignment 
 of the places and qualities of the rocks of any territory serves to 
 exclude what would lead to a fruitless pursuit, as it gives ground 
 for rational research in other places ; thus marking the bounds 
 of the probable and the impossible, and thence limiting hopes, 
 and, with that, checking vain expense or imposture, as it confines 
 both hopes and labour to a rational direction. 
 
 The present geological, or mineralogical. Map of Scotland 
 has done this, if it has done no more. It has marked the 
 places of the admitted metalliferous rocks, and it has equally 
 noted where metals cannot be expected and will not be found. 
 In this it has done what it has for the coal series ; as the 
 researches on this collection of strata will serve to illustrate 
 its utility respecting the possible metals of that country. No 
 one needs now seek for coal in Scotland, where the carboni- 
 ferous strata are not here laid down: he who makes or pro- 
 poses such a search in the districts where the primary rocks 
 come to the surface, is either in a state of ignorance which 
 requires to be informed, or is a wilful deceiver who can now be 
 detected by any one who will inspect this Map, even had he no 
 
131 
 
 Geological Map of ' Scotland. 
 
 geological knowledge. Thus it is as to the hopes or expectations 
 of metallic mines; they may possibly be found, though this has 
 not yet happened, in the primary rocks, in the mountain lime- 
 stone, and in certain of the trap rocks ; but excepting the iron 
 stone of the coal series, they will scarcely be found any where 
 else : I need not note here some very rare exceptions to this 
 general rule. 
 
 Nor could this Surveyor w^ell have done more than has been 
 done; or this Map, or its Memoirs, recorded more on this sub- 
 ject than the little which will be shortly noted. The search for 
 metallic minerals forms a very difierent pursuit from the assign- 
 ment of rocks and their boundaries. It is almost a microscopic 
 pursuit : it is at least a very minute one. Over such a country 
 the lives of hundreds, occupied for centuries, would not discover 
 what exists, should aught of this nature exist, or, reversely, 
 decide that the pursuit of metals was worthless or hopeless. 
 The very smallest space easily selected might occupy the entire 
 labours of one man; and assuredly no labour could well be 
 worse applied. Every discovery of this nature in an unknown 
 country, or in one not previously known to possess metallic mine- 
 rals, is the result of accident, and can seldom be otherwise, even 
 in scientific hands ; while no one will be induced to search, with- 
 out guide or hope; least of all, thus to waste time on which 
 there are abundant other demands. In a land of such minerals, 
 in tracts above all where mines have been wrought, such a pur- 
 suit would be more rational, while it may sometimes succeed, as 
 the result of a design founded on some kind of evidence ; and 
 more especially where veins can be followed or sought under 
 expected prolongations from known ones, or under other known 
 modes of examination which I need not here detail. 
 
 But nothing can well be less tempting to such pursuits than 
 the condition of Scotland in respect to mines and metallic mine- 
 rals, as far as it is yet known. There is scarcely a guide or an indi- 
 cation to tempt any one to an examination, even of the few miles 
 to which he may have access on every day of his life. To the 
 geological surveyor, fully employed in wider pursuits, requiring 
 a very different kind of attention, and to the distant far more 
 often than to the near, there is not only none whatever, but it is 
 nearly impossible that he should combine both, so diverse or 
 opposed are they : it would be an utter impossibility, not merely 
 an inapplicable and censurable waste of time : under one nar- 
 rowly limited, as in the present case, it would be to leave much 
 of the intended and fundamental work undone. If he should 
 find any indications of a metallic vein not known before, he has 
 no more merit in the discovery than the most ignorant would 
 possess ; since it is not his science which has led to it ; though 
 the knowledge of minerals would doubtless, often enable a geo- 
 logist to see what others might overlook, especially were the 
 indications minute, or the mineral devoid of ostensible metallic 
 characters. 
 
 K 2 
 
132 Memoirs to II. M. Treasury respectiny the 
 
 In truth, discoveries of this nature must be the result of pure 
 chance ; and how little likely such chances are to occur in a 
 country so barren of metallic minerals as Scotland, 1 need not 
 say. The merest shepherH who traverses the mountains in his 
 daily range, has also a better chance than the geologist, from 
 the minuteness of that range and from the time which he is occu- 
 pied on it. This at least is true wherever the mineral has a me- 
 tallic aspect ; in other cases, the mineralogist would, of course, 
 possess the advantage. 
 
 Nor are these very observant persons inattentive to such sub- 
 jects. An expectation of the existence of metals in Scotland had 
 been excited early in the last century ; it w^as much increased at 
 a subsequent period, and fostered especially by the visit of Mr. 
 Raspe, and of some others, not always very honest, whom I 
 need not name. It has therefore not slept in the memories of 
 the rural population, however the pursuit may have cooled : 
 while there are few among the shepherds, quarrymen, road con- 
 tractors, and others, who have not an eye capable of distinguish- 
 ing an unusual mineral, though they should not know its name, 
 and though they might be suspected of want of discernment by 
 the geologists who find that they possess so few names for rocks. 
 
 I have accordingly never failed to cultivate the acquaintance 
 of all these classes, as I have occasionally received specimens 
 from them, of whatever nature, and been conducted by them to 
 the places of their imagined discoveries and hopes : convinced 
 that this is the best plan which a surveyor can adopt on such a 
 subject. How very little I have gained in consequence, I need 
 not say, since it has proved to be next to nothing, and without 
 value : while if it has been my fortune to chance upon a few in- 
 dications of metallic veins, or on metallic minerals in some form, 
 the result, trifling as it has proved, is even more than I had a 
 right to expect. These will be noted with the rest, in the ap- 
 pended catalogue : though it is quite unnecessary for me to dis- 
 tinguish, on every occasion, between what I have myself noticed, 
 and that which had been previously known, as it has been printed 
 at several times indifferent popular books. Had I not supposed 
 that such a list would be expected, and its omission deemed an 
 unpardonable negligence, there is very much that is undeservino- 
 of being reprinted or noticed, from the doubtful nature of the evi- 
 dence, the obscurity of the places, or the impossibility of now 
 tracing any indications of what was asserted to be, or to have 
 been. A work on pure science, which such a Memoir as this 
 cannot be, would not have condescended to notice things resting 
 on doubtful evidence, or on ignorant and popular tradition. 
 
 Whatever mines may have been wrought here in former times, 
 of which some were rather attempted than pursued, there are 
 but four, as far as I can And, actually working. Of these, the 
 mine at the Leadhills is the only one which is returning any pro- 
 fit, as far as my information goes : though I must speak with 
 some hesitation respecting the others ; since, within the period 
 
Geological Map of Scotland. 133 
 
 of my own knowledge and examinations, one, if not more of 
 these, have been wrought and again abandoned, and that at 
 Tyndrum, I understand, resumed. I do not know whether 
 Strontian has been re-established since my visit, now of many 
 years date, but I am informed that it never produced any profit. 
 Latterly, I understand that this is also the case with Tyndrum ; 
 or that this, as well as a very feeble attempt, equally on lead, 
 near Newton Stewart, is barely sufficient to carry on the expense 
 of working. It is difficult however to procure the needful infor- 
 mation on subjects of this kind, since it is confined to the pro- 
 prietors or lessees, not very likely to afford it, even were they 
 known to me ; nor is it an essential part of a Memoir of the 
 present nature. 
 
 I may now say, that neither these mines, nor any others of 
 those which are recorded, in print or in tradition, afford any 
 basis on which to proceed in making further researches than 
 those which have been already made on the probable or possible 
 courses of the veins in which they are wrought. I mean, how- 
 ever, in this, to say that they would not justify any farther 
 researches from a geological general surveyor than such as could 
 be made under a small expenditure of time, in the course of his 
 proper work. Such a pursuit belongs to the proprietors, and it 
 is for them to see whether they would expend money on such 
 subjects, under the employment of professional miners. 
 
 What the actual state of public feeling in Scotland may be 
 on this subject, I have not been able to discover ; while, as far 
 as I have seen, it has somewhat vacillated within my own me- 
 mory, and is so different among the proprietors that I have 
 known, as to lead to no general conclusion. High, and even 
 extravagant expectations of the possession and of the value of 
 mines in this country, were entertained by landed proprietors 
 during a portion of the last century ; while, during no incon- 
 siderable period, many trials were made, and some money fruit- 
 lessly expended. There was an excitement of hope, which 
 some contemporary writers considered a mania : and it is well 
 known that these hopes were encouraged by impostors who found 
 their interest in so doing, to the entire falsification of the facts, 
 in making reports of metals that never existed, and even, as is 
 common in mining countries, in secreting specimens within cavi- 
 ties or workings, whence they were afterwards produced as 
 evidences. 
 
 But if I have seen rightly, there has been no small revolution, 
 for some time past, in the public opinion ; which has also, as is 
 not unusual, been carried to such an extreme as to consider 
 Scotland peculiarly barren in metallic minerals. Those who 
 think in this manner strengthen their argument also by the cases 
 of Cumberland, the Isle of Man, Wales, and Carnwall, in 
 which metallic minerals occur or abound; countries not veiy 
 distant, and the two former in particular, intimately connected 
 with at least the south of Scotland, by geographical position ; 
 
 K 3 
 
134 Memoirs to H. M, Treasury respecting the 
 
 as the whole consist chiefly of the same rock which constitutes 
 the larger portion of this division of that country. 
 
 This assumption is at least a rash one : it is, at any rate pre- 
 mature ; while the same argument might be used for the opposite 
 conclusion. It is premature, as long as Scotland has not expe- 
 rienced the same attention which has been bestowed on the 
 tracts in question ; and if the slate of the south has already pro- 
 duced the mine of the Leadhills, it is a fact which maintains the 
 general analogy betwixt all these districts, sufficiently at least to 
 prevent the renouncement of all hope. Metallic veins do not 
 often appear conspicuously at the surface: discoveries of this 
 nature are, notoriously, more the result of chance, than of re- 
 search for such specific purpose : and if Angiesea has thus given 
 to light its Parys mine, there is no absolute reason why similar 
 discoveries may not be made in Scotland, not only in the slate 
 rock in question, but in many others. 
 
 In the mean time, there seems nothing to be done but to wait 
 for similar accidents. Such, any discoveries must almost always 
 be, in whosever hands ; nor will a hundred such surveys as the 
 present ensure one discovery, though casualty may fall on a few. 
 The conclusion therefore to be drawn, is, that it is at present 
 fruitless to expend time or money in the search after metallic 
 deposits in Scotland, as far at least as the mineralogical expe- 
 rience hitherto attained is concerned, although geological prin- 
 ciples are far from destroying our hopes respecting their existence. 
 
 If this be the conclusion of mere science, I conceive that it 
 is strengthened by other views. Every sound economist will, I 
 imagine, consider it bad policy that Scotland should expend its 
 capital on such pursuits, when that which it possesses is so use- 
 fully and profitably employed. It has yet lands to reclaim and 
 plant, roads to make, and far more of all that must tend to the 
 improvement of its agricultural territory and produce : while it 
 may still extend, from the same fund, that system of manufac- 
 tures and commerce in which it has lately been making so rapid 
 a progress. All can see what it has already gained by these 
 applications of its activity and capital : and few, I believe, will 
 think that it would have done better, had even the smallest por- 
 tion of these been diverted to mining speculations. That which 
 has hitherto been a right proceeding, will also probably be the 
 most prudent one for a long time to come. It ought not, if 
 I am right, to regret at present, that it finds no mines ; nor 
 ought it to pursue those indications which it already possesses. 
 It will be time enough to do this when, like England, it overflows 
 with capital which it cannot apply : and, when that time arrives, 
 it may possibly become that mining country which it is not at 
 present, to whatever conclusions mere science may have come on 
 this subject. 
 
 I must not thus judge however with respect to a proposal 
 which was made some years ago, and which, in the present state 
 of British capital, may possibly be renewed. I allude to that 
 
135 
 
 Geological Map of Scotland, 
 
 endeavour to establish a mining company, which was made some 
 years since, but which was abandoned in consequence of the re- 
 fusal of Government to grant this portion of the Island a charter, 
 as it had done to Ireland. In such a case, the subscribed capital 
 would probably be chiefly English, as it was in the former one ; 
 while the minuteness of the shares could cause little incon- 
 venience to any person, though no profit were returned, or even 
 though the whole should be lost ; and, while whatever might be 
 expended on Scottish labour, could not be considered as abso- 
 lutely wasted. 
 
 To these general remarks I may lastly add, as connected more 
 especially with my own pursuit, that I took occasion to examine 
 every spot, the seat of present or ancient mines, or merely of 
 metallic minerals, to which it was possible to get access ; since 
 there were many which could not be found. Of these, some 
 which had unquestionably been either wrought or tried, seemed 
 to have been exhausted, or abandoned from their poverty : the 
 places of others had been forgotten by the country people, or 
 else had become so obscured by the usual changes of the surface 
 as to be undiscoverable : while of many that were named to me, 
 or recorded in print, I had reason to doubt whether they had 
 ever existed. In no instance did I see anything which could 
 tempt to a further expenditure of money, except where I have 
 noted such in the appended catalogue of places : and, of many, 
 to which I was particularly directed under great assurances, it 
 was evident that the popular reports were false ; the result of 
 traditions exaggerated by the people, under the usual feelings of 
 mining countries. The reports of silver mines were especially 
 numerous, while they carried improbability on the very face : 
 and having examined, in particular, the two principal spots thus 
 pointed out, I found reason to conclude that these had been 
 merely lead mines, doubtless yielding some silver, but which 
 never could have produced much, even of the baser metal, since 
 the workings had been very confined, and seemed to have been 
 abandoned after very little labour had been bestowed on them. 
 
 I must now give a general List of the metals which have been 
 found in Scotland, or which it is said to have produced, before 
 I proceed to the Catalogue of the places which I have collect^ . 
 since the falsity of the reports as to some of those, requires that 
 they be noted in a separate list, for the purpose of excluding 
 those which could not appear in a catalogue of places, and might 
 therefore seem to have been overlooked. i • u t 
 
 But I must previously observe, that in everything which 1 
 have yet said, I have excluded iron. If found, in some coun- 
 tries, in situations analogous to those of most other metals, this 
 is not the case at least in Scotland, with a slight exception 
 hereafter noticed. In the form of ironstone, accompanying the 
 coal strata, it is sufficiently common, and it is thus, on every 
 ground, excepted from these general observations ; while, to 
 
 K 4 
 
13G Memoirs to H, M. Treasury respecting the 
 
 seek or find it, is almost a matter of course. I need not there- 
 fore name its places in the general Catalogue. 
 
 Catalogue of Metals, proved or asserted. 
 
 Gold : alluvial. 
 
 Silver : in lead ore only. 
 
 Quicksilver. This is said to have been found once in Isla, 
 in its native state, and in a single place. It has never been 
 found since, nor any of its ores. This, with the fact that the 
 metal was produced by the asserted finder, in a quantity of some 
 ounces, forms a combination of circumstances sufficiently suspi- 
 cious : as those are increased by knowing that the proprietor was 
 both opulent and liberal, so as to have been the prey of pre- 
 tenders or impostors, some of whom persuaded him to mine for 
 coal in mica slate and quartz rock. 
 
 Copper : in many places, but never wrought to any result. 
 
 Lead : in several places : in one at least, largely wrought. 
 
 Zinc : not wrought to collecting. 
 
 Antimony : in one place. 
 
 Titanium : in two ores : common, but scanty. 
 
 Arsenic : in the lead mines of course. 
 
 Iron. Iron stone, abundant. Pisiform hematite, in one 
 place. Traces of chranat in all the serpentines, but as yet no 
 veins or distinguishable masses : except in Shetland, which is 
 not included in this Survey. Bog ore, not uncommon. Pyrites 
 very rare. 
 
 Cobalt: reported to have been found near Alloa : not now 
 to be found, and no specimen existent, to my knowledge. 
 
 Chrome. The oxide: almost invisibly, and very rare, in 
 serpentines. 
 
 To these I may add Blacklead, as a nearly metallic condi- 
 tion of carbon, while popularly viewed as a metal. 
 
 Catalogue of the Places, as far as known or asserted, where the 
 above-named Metals have been found. 
 
 Gold. This is known to have been found in the river alluvia 
 of Crawford moor, in ancient times, and is reported to have 
 abounded sufficiently for the purposes of coinage. It may still 
 be procured by washing in the usual manner ; but, as the people 
 in this part inform me, will seldom yield more than a third of 
 the wages of common labour. A nodule of considerable size was 
 found, not many years since, near Helmsdale in Sutherland, 
 which 1 have seen in the possession of that noble family. 
 
 Silver. The places where this metal was found, combined 
 
Geological Map of Scotland, 137 
 
 with lead ore, are the following, as far as I know : of which I 
 have examined the first two ; no one having been able to point 
 out the places of the others. 
 
 In the trap and limestone hills between Linlithgow and Bath- 
 gate : marked as silver mines in the county map : several work- 
 ings resembling quarries : no attainable report of the produce : 
 abandoned from a time which no one seems to know. 
 
 In the Pentland (trap) hills, not far from Pennycuik : called 
 Silver holes : seem to be marked in the present Map by the 
 word Silver burn, though the geography is here uncertain : what 
 I saw resembles the working of quarries. As in the former case, 
 no attainable record of the produce or the date: long since 
 abandoned. 
 
 Ecclesmachan. Said to have been once wrought: but no 
 report of time or produce. The place now unknown to the 
 country people to whom I applied. 
 
 A Iloa, Said to have been wrought in the trap of the Ochils. 
 I was unable to procure information respecting the spot, and can 
 find no record of either the produce or the times of working and 
 abandonment. Some printed reports are evidently the extrava- 
 gance of popular tradition. 
 
 Copper. The reports of the finding of copper, or some traces 
 of it, are numerous ; but there are only a few instances where it 
 is said to have been wrought. Many of those reports are so 
 vague as to admit of considerable doubt respecting their veracity. 
 Of many others, I am compelled to say that I could get no in- 
 formation respecting the exact spots, or that when I did so, and 
 was even attended by the pretended guides, I could find nothing. 
 Of the few that are said to have been once wrought, I could 
 never find that any one knew of their produce, their dates, or 
 aught else ; nor do I find that marketable copper ore can be 
 proved to have been produced. If that has happened, the 
 records must be locked up in the papers, or existing in the me- 
 mories or traditions, of the proprietors, and it would be a fruit- 
 less task to seek for them : at least the information could be of 
 little value, under all that has been proved respecting the former 
 mining, real or pretended, of this country. I must note these 
 places as I best can : lest I leave as an obvious blank, what 
 when filled, is seldom better than a blank as to science or 
 economy. 
 
 Applecross, No place specified in this wide district. 
 
 Airthrie near Stirling : not to be found through any informa- 
 tion that I could obtain : no produce recorded. 
 
 Ord of Caithness : mere traces. 
 
 Clythy Caithness : the same. 
 
 Kilmartin in Knapdale : not to be found ; by me at least. 
 
 Binny, near Linlithgow : no place pointed out now. 
 
 In the parishes of Longformacus and Lauder. I could find 
 no one acquainted with the spots, nor hear of former workings. 
 
 Alloa : reported to have been found and wrought in the same 
 
138 Memoirs to H, M, Treasury respecting the 
 
 mine with the silver-lead already noticed, and with cobalt. Ad- 
 mits but of the same remarks as the former of these metals, 
 already given. 
 
 Hoardwilly in Buncle, Berwickshire. Said to have been 
 wrought : not now known, from any inquiry that I could make. 
 
 Morven, near Sanda : marked in this Map. I could not find 
 it, nor ascertain that it had ever been wrought. 
 
 Near Stair in Ayrshire : said to have been wrought, together 
 with antimony : no other information to be procured. 
 
 Logie, in Perthshire : said to have been wrought. Equally 
 obscure, and apparently forgotten. 
 
 Near Dunkeld, The presence of copper pyrites had been here 
 noticed. The vein, as I investigated it, is in mica slate, and 
 some feet thick. I caused it to be wrought by two men during 
 one day, and there were produced thirty pounds of ore, within a 
 few feet of the surface. This is a highly promising indication : 
 and as the vein is soft, and could be wrought a considerable way 
 by a common drift, it well deserves a further pursuit. The ex- 
 pense of the very little labour bestowed on it was far more than 
 repaid. The exact place is well known on this estate. 
 
 Lead. I need not repeat the same general remarks on this 
 metal : they are no other than what 1 have made respecting 
 copper. 
 
 Ben Ledi, Traces have been found. 
 
 Skinnet Hilly Caithness. The same. 
 
 At Sandside, in the same county. The same : and similar 
 traces have been observed in other parts of this county. Of such 
 as I have seen, here as elsewhere, 1 may say literally, that they 
 are but traces : being very commonly detached grains rather than 
 masses, as the apparent constituents of rocks, and leading to no 
 hopes of metallic veins. 
 
 Clunie in Braemar. I here found a considerable vein of fluor 
 spar with traces of lead. It might deserve some further exami- 
 nation by the proprietor. 
 
 Chapel of Gary, Aberdeen. I observed abundant fragments 
 of lead ore imbedded in the rocks : but could see nothing that 
 indicated a vein, or could tempt to any expensive examination. 
 
 Tinto. In the trap (porphyry) of this hill, there are numerous 
 veins of sulphate of barytes, with indications of lead. I did not 
 hear that they had been observed by the people, or that any 
 attempts to examine them had been made in former times. 
 Whether deserving it or not, I had no means of ascertaining. 
 
 Coll. I examined a vein of lead ore in this island, which has 
 long been known, but never wrought. It is very narrow, and 
 lies in a very tough gneiss : I doubt if it would justify aught but 
 a very superficial trial. 
 
 Ballater. I also examined here some veins on which a little 
 money had been fruitlessly expended. The rock is most refrac- 
 tory, and the veins very small and very poor. 1 imagine that it 
 belongs to the same set of appearances, or traces, of which there 
 
139 
 
 Geological Map of Scotland. 
 
 are so many in Scotland ; and tliat it holds out, now at least, no 
 temptation to a further expenditure. 
 
 Isla. If I am rightly informed, the lead, which here lies in 
 primary limestone, did once produce some profit, while the 
 excavations are not inconsiderable. I am disposed to doubt the 
 fact of profit, where no statement was produced, because the pro- 
 prietor, at the time of my visit, was equally enlightened, opulent, 
 and anxious for every kind of improvement, while these mines had 
 been offered to speculators in vain. The present proprietor can 
 afford more correct information, should this statement be wrong. 
 It is not, at least, a favourable a place for deep mining, as it 
 would be expensive to drain. 
 
 Alloa. Whatever might be said of lead here, has already been 
 noted under the head of Silver. I may say the same of the tract 
 between 
 
 Linlithgow and Bathgate ; and also of 
 
 Ecclesmachany and of the silver holes of the 
 
 Pentland Hills. 
 
 Traquaivy near Peebles. I could obtain no specific informa- 
 tion respecting this place. Nor of 
 
 Westwater and BroomholnXy near Langholm. 
 
 Inverneil in South Knapdale. The lead is said to have been 
 once wrought here ; but there was no one to inform me of the 
 facts. 
 
 Glen Shira. A lead mine is here marked on the Map. I could 
 find no printed information respecting it : my guides could not 
 point out the spot, nor did any one seem to have heard of its 
 history. At any rate, it is not wrought now. 
 
 Glen Nevis. No one in the neighbourhood now seemed to 
 know of this place, which I imagine to have been noted by Mr. 
 Williams. To be thus forgotten, seems a sufficient proof of 
 insignificance. 
 
 Inver scaddlcy near Fassafern. This admits of the same remarks. 
 
 Kemhuch Point in Fife. I have read of what I could not here 
 find, and no one seemed to know. 
 
 CairndrocMy near Killin. Lead is said to have been wrought 
 here. What the trading mineralogist of Killin, a person of great 
 accuteness and research, did not know, I could have no hopes 
 of finding. 
 
 Near Ardoch, on the road between Fettercaim and Loch Lee. 
 I was assured that lead mines had formerly been wrought here 
 to a great extent, that the miners had secreted the ore and be- 
 come very rich, with more which I need not record. I narrowly 
 examined this place. There are remains of lead ore scattered 
 about, but no marks of extensive workings, nor any trace of a 
 vein to be seen at present, though such may exist, obscured by 
 the soil and fragments. It is in Lord Panmure’s power to re- 
 examine this spot : but the reports bore strong marks of absurd 
 exaggeration. 
 
140 
 
 Memoirs to H. M. Treasury respecting the 
 
 Glenlyon. I was informed by the late Duke of Atholl that 
 this valley contains two lead mines, and that they were once 
 wrought; while they ought to have been of some value, or pro- 
 mise at least, since, in selling the land, he had retained his right 
 over the minerals. No papers in evidence were however found, 
 nor could the exact spots be described to me. I could gain no 
 information in the neighbourhood, and consequently sought for 
 them in vain. 
 
 Cumherhead hills, Lanark. I merely read that lead had been 
 found here. 
 
 Lead-hills. It would be superfluous to make any remarks on 
 a mine so well known : while I can only conjecture that the lead 
 said to be found at Craivford John, Glendorch, and Gilkers- 
 cleugh, belongs to veins of the same general description, though 
 probably insignificant, as no one could point them out to me. 
 
 Tyndrum. The mine working : in an alternation of mica slate 
 and quartz rock ; I believe to little profit. 
 
 Near Castle Wig, Galloway. I was informed that lead ore 
 existed here, offering some temptation : but not having heard of 
 this till I had quitted the country, could not institute any exami- 
 nation. 
 
 Ikon. To what I have already said on iron I can add nothing. 
 I did not find the spot in Ayr which produces pisiform hematite, 
 and as to the bog iron ore, it is as worthless as it is diffused, 
 though rarely in large quantities in one spot. 
 
 Titanium. Rutile abounds in the hills north ofKillin, being 
 in quartz veins, of which the detached fragments strew the sur- 
 face very widely. 
 
 It is however but a matter of mineralogical curiosity to point 
 out this mineral ; as, independently of the limited use to which 
 titanium is applied, it is not here in such a state as to be extracted 
 for use. It is even more a matter of such curiosity to name 
 Sphene as common in the granites of Scotland ; being abundant 
 in Glen Tilt, for example, and far more so in Criffel. 
 
 Zinc. I know not that this has been found any where but at 
 Tyndrum. The ore, brown blende, is not very abundant, and is 
 thrown away, as it deserves. 
 
 Lastly, Black LEAD has been found inGlenElg,inStrathpeffer, 
 at Stair in Ayrshire, and at New Cumnock, at which last place 
 its remarkable mineralogical relations are well known. Here it 
 has been wrought for pencils : I knew not that it has been ap- 
 plied to that purpose, from any of its other situations. 
 
 If I had thought that it was a needful or fitting portion of this 
 Report to give a catalogue of the earthy minerals occurring in 
 Scotland, I might easily have done so ; while I can refer to one 
 which I formerly published in one of the Scotch scientific jour- 
 nals, and which requires but little addition to be completed to 
 the present state of our knowledge on this subject. But this 
 neither belongs to economical utility nor to the other objects of 
 
Geological l^ap of Scotland. 141 
 
 this Survey : it is a mere mattler of curiosity, or of interest to the 
 collectors of minerals. 
 
 I must finally add, that I have made no attempt to represent 
 the places of mines or metallic minerals on the Map, thoug;h re- 
 ferring to some which the geography has recorded. Those which 
 are wrought are so well known that it would have been super- 
 fluous to mark their places by a hieroglyphic, few as they are : 
 as indeed the names in the Map form a sufficient indication. There 
 is not evidence enough as to some, to note them as facts : of others, 
 as has been shown, the places could not be found ; while, of the 
 remainder, the minuteness and inaccuracy of the groundwork 
 did not permit a true record ; and while, moreover, although all 
 this had been otherwise than it is, marks so necessarily minute 
 as they must have been, could not have have been found on such 
 a Map, had there even been colours for them, remaining unoccu- 
 pied. The Catalogue will suffice for all the required purposes; 
 while the names thus given will be at least as good a guide as 
 such an entry could have been, and with even less tendency to 
 mislead an observer or inquirer.