LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 GIKT OK 
 
 t 
 
 . Received 
 Accessions 
 
Geological and Solar Climates 
 
 Their Causes and Variations. 
 
 A THESIS. 
 
 BY 
 
 MARSDEN \IANSON, C- ED 
 
 Geology and Physics: 
 UNIVERSITY OF CALIFORNIA, 
 
 May, 1893. 
 
Entered according to Act of Congress in the year 1893, 
 
 BY MARSDEN MANSON, 
 In the office of the Librarian of Congress, at Washington, D. C. 
 
 V 
 
 SAN FRANCISCO: 
 
 George Spaulding & Co., Printers. 
 
 414 Clay Street. 
 

 ERRATA. 
 
 Preface, next line to last, for ivaiver read waver. 
 
 Page 5, foot-note, 7th line from bottom, for Helvetic <- 
 read Helvetic. 
 
 Page 14, in foot-note, 6th line from top, for Zeno- ^ 
 graphic read Zenographical. 
 
 Page 17, last line, for area read era. ~~ 
 
 Page 20, 14th line from top, for wherever read whenever. *^ 
 
 Page 23, 3d line from bottom, for area read era. ^ 
 
 Page 23, 4th line , fro in bottom, for merging read-' 
 emerging. 
 
 Page 41, 15th line from top, after necessary for the, ^ 
 insert, removal of glacial conditions, and for the 
 
 Page 44, the second paragraph should read: The 
 trapping process not being a function of the orbital dis- 
 tance, nor of the actual amount of heat received, but 
 of the composition of the atmosphere, this rise, etc. 
 
 Page 47th, 6th line from top, insert " at end of para- -" 
 graph, after out. 
 
 Ib, 6th line from bottom, for * substitute f. *- 
 
PREFACE. 
 
 The worshipers of truth are delving in every ham- 
 let many have before them the daily burdens of life, 
 from which they can snatch but a few hours each day to 
 give to their chosen faith. 
 
 Every now and then one comes forward with some 
 skillfully carved jewel which he has wrought into shape 
 to deck his shrine. Sometimes it is only a little piece 
 merely good for inlaying the walls, yet it fits well in its 
 place and strengthens the faith of other workers. Again 
 it is the great keystone for some massive arch whose other 
 stones were laid in bygone times. Yet again it is a 
 mighty truth that will not fit in the great building 
 at all until the wrong work be torn down, and then it 
 forms the base for one of the steadfast and everlasting 
 towers. So pure must be the faith of those who bow 
 at the hallowed shrines of truth that they would tear 
 down these shrines rather than let them stand upon, or 
 even harbor error. 
 
 The writer gives in this little book a keystone which 
 he knows will not fit in the present building unless 
 some errors be torn out. Those whose faith is true 
 will not wajfver nor come grudgingly to the work of re- 
 building. 
 
> OP 
 
 GEOLOGICAL AND SOLAR CLIMATES, 
 THEIR CAUSES AND VARIATIONS. 
 
 THE CAUSE OF THE ICE AGE. 
 
 ' ( The most important problem in terrestrial physics * * 
 and the one which will ultimately prove the most far reach- 
 ing in its consequences, is: What are the physical causes 
 which led to the Glacial Epoch and to all those great secular 
 changes of climate which are known to have taken place 
 during Geological Ages?" (Dr. Croll, Climate and Cos- 
 mology.) 
 
 "An attentive study of the physical Geography of the 
 earth and its influences on Climate, together with a 
 judicious application of the simplest physical theories, will 
 enable us to gain by and by a better knowledge of Geologi- 
 cal climates." (Prof. A. Woeikof, Nature, March 2, 
 1882, p. 426.; 
 
 Since Agassiz announced* the past existence of an 
 age during which ice covered temperate and tropical 
 land areas, the cause of this wonderful phenomenon has 
 been a problem of profound interest. Upon the cor- 
 rect solution of it hinges also the cause of Geological 
 climates. 
 
 *In 1821 Venetz called attention to the once greater extension of Glaciers; 
 and in 1824 Prof. Esmark made similar observations as to the Glaciers of 
 Norway. Phil. Mag., Vol. XXVII, p. 321. 
 
 As early as 1821 a prize of 300 livres was offered by the He^ivitic Soc. of 
 Nat. Sci. for the collection of facts regarding the increase or decrease of 
 the extension of glaciers in the Alps. Tillock's Phil. Mag., Vol. LV1I, p 
 307. 
 
 But to Agassiz belongs the honor of having first pointed out the exist- 
 ence of the, Ice Age wnen all glaciers were vastly more extended than at 
 present. 
 
6 GEOLOGICAL AND SOLAR CLIMATES, 
 
 So great has been the interest attaching to this sub- 
 ject, that more study has been devoted to it during the 
 past fifty years than perhaps to any other in Geology; 
 hardly a leading scientific magazine runs through a 
 year's numbers without one or more articles upon it; 
 and no Geological Society is without zealous students of 
 glacial phenomena. Some have become so absorbed in 
 the subject that, led by the recurrence of certain slight 
 astronomical influences, they recognize a glacial period 
 for slight and widely scattered evidences of possible 
 early local glaciation, forgetful of the fact that an era of 
 frigid climate could not intervene between two eras of 
 tropical climates without the intervention of eras of tem- 
 perate climates. 
 
 The evidences establishing the reality of the Ice Age* 
 during the Quaternary period are now beyond dispute. 
 It is difficult, however, to establish by geological evidence 
 the synchronal glaciation of all the continental areas 
 known to have been heavily glaciated. This difficulty 
 arises from the fact that the identity of various strata 
 has to be established by fossils of varying conditions 
 and characters; it is also rare that the same geologist 
 has visited and compared the evidence upon more than 
 two continents, thus eliminating probable errors from 
 unequal subaerial denudation and exposure in the differ- 
 ent zones of present climates and upon different conti- 
 nents. Again, the proof of the contemporaneous existence 
 of corresponding strata upon different continents in the 
 same latitude is sometimes attempted by a comparison 
 
 * The writer prefers the nomenclature of Dr. Geikie and others using the 
 term Ice Age rather than Glacial Epoch, or Period. The duration of this 
 age was not recorded in the same manner and terms as either previous or 
 succeeding ages; this is due to the inactivity, or even absolute suspension 
 of the great forces, heat and moisture, over continental areas during this 
 age; under estimates of its duration are thus liable to be made. 
 
THEIR CAUSES AND VARIATIONS. 7 
 
 of land fauna and flora, with marine fauna and flora, or 
 even by more complex comparisons. Fossil plant life is 
 by far more reliable than animal life for comparative 
 purposes. 
 
 Another misleading factor is found in the interpreta- 
 tion of the great trans-continental lines of terminal 
 moraines into the absolute limits of glaciation. Con- 
 sidering the great lapse of time since the removal of 
 glacial conditions in temperate and tropical latitudes, it 
 is more than probable that the existing unobliterated 
 evidences by no means mark the extreme limits of a 
 lighter and more extended glaciation whose traces have 
 been destroyed, but which can justly be interpolated 
 between the existing very marked traces of enormous 
 glacial extension during Quaternary times. It is not 
 impossible, nor entirely improbable, that early local 
 glaciation did not occur v during the early part of the 
 Cenozoic Era, or even earlier, but the data upon which 
 to establish the occurrence of such early local glaciation 
 are both meagre and obscure. Should the evidences of 
 such early local glaciation be developed beyond dispute, 
 they will in no way interfere with the interpretation to be 
 given, but they will strongly corroborate certain portions 
 of this interpretation. So far as the author has been 
 able to examine such evidence, it has been found to be 
 between strata containing fossil life of a torrid character, 
 with no evidences of a gradual merging into a temperate 
 climate above and below it, as in Quaternary glaciation.* 
 
 Before entering further into this discussion, it may not 
 be out of place to briefly review the principal theories 
 advanced to account for the Ice Age. It will be seen 
 that physicists and astronomers have vied with geolo- 
 
 * This question is so important and has so broad a bearing that it will 
 be reverted to later under the heading Palaeozoic Glaciation. 
 
8 GEOLOGICAL AND SOLAR CLIMATES, 
 
 gists in the diligence of the search for the cause of this 
 age, and their minds have been as fertile in the number 
 of causes assigned as the true one. Not one of all the 
 causes suggested has been sustained by argument without 
 a flaw in the reasoning, and 110 demonstration has been 
 made which has carried conviction to the scientific world. 
 
 It would not be instructive to attempt to review all of 
 the theories which have been urged. The tendency to 
 ascribe remote inadequate or obscure causes, rather than 
 to interpret facts and phenomena in accordance with 
 known laws, is apparent in many. Some writers have 
 ascribed causes resting only upon hypotheses beyond the 
 range of either analysis or investigation; such hypotheses 
 can only stand in the absence or failure of all other 
 assignable causes. Therefore the leading causes only 
 will be briefly mentioned. 
 
 In a recent monograph on the subject, the following 
 are given :* 
 
 1. A decrease in the original heat of the globe. 
 
 2. Changes in the elevation of land, and consequent 
 variations in the distribution of land and water. 
 
 3. Changes in the obliquity of the axis of the earth. 
 
 4. A period of greater moisture in the atmosphere. 
 
 5. Variations in the amount of heat radiated by the 
 sun. 
 
 * Transactions of the Technical Society of the Pacific Coast, Sept., 1891, 
 Vol. VIII. See also The Climate Controversy, S. V. Wood, Jr., Geol. Mag., 
 1876 and 1883. Climate and Time, Climate and Cosmology, Croll. Island 
 Life, Alfred Russell Wallace, F. K. S., etc. Philosophical Magazine, May, 
 1864. British Association Keports, part 2, p. 11. Proceedings Royal 
 Soc., vol. xxviii, p. 15. Quart. Jour. Geological Soc., Feb., 1878. Nature, 
 July 4, 1878. Trans. Geological Soc., Glasgow, Feb. 22, 1877. The Ice 
 Age in North America, Dr. Fred. G. Wright, Appendix by Warren Upharn. 
 The Cause of an Ice Age, Sir Robert Ball, F. R. S., etc. Revolutions de 
 la Mer. Deluges Periodique, Alphonse Joseph Adhemar. 
 
THEIR CAUSES AND VARIATIONS. 9 
 
 6. A variation in the heat absorbing power of the 
 sun's atmosphere. 
 
 7. Variations in the temperature of space. 
 
 8. A coincidence of an Aphelion winter with a period 
 of maximum eccentricity of the earth's orbit. 
 
 - 9. A combination of 8 and 2. 
 
 10. The views of Sir Robert Ball, LL. D., etc., as 
 expressed in his recent work, The Cause of an Ice Age* 
 
 The first of these theories is universally admitted, 
 and taught in even elementary works on Physical Geog- 
 raphy, but it fails to account for all the phenomena ac- 
 companying the Ice Age, or to account for the disap- 
 pearance of that age, and, so far as the author is aware, 
 has not been presented in such form as to satisfactorily 
 account for geological and present climates in rigid con- 
 formity with the facts and known laws. Nor has it been 
 presented in such form as to account for that era of geo- 
 logical climates known as the Ice Age; moreover, it fails 
 to account for the disappearance of that Age. 
 
 The second has been proved to be a local and corre- 
 lated phenomenon, but cannot be accepted as a cause, 
 since glaciation did not solely -depend in the same lati- 
 tudes upon elevation above sea level. 
 
 As to the third, whilst slight changes in obliquity 
 have occurred, and must continue to occur, the results 
 are too slight and the distribution of glacial phenomena 
 is too general to warrant the acceptance of such change 
 as a prime cause. 
 
 The fourth is a necessary consequence of the first, 
 but, like the first, fails when the crucial test of account- 
 ing for the disappearance of the continental Ice Sheets 
 is applied. 
 
 * See also The Date of the Last Glacial Epoch. Gen. Drayson, R. A. 
 Science, Nov. 25, 1892. 
 
10 GEOLOGICAL AND SOLAR CLIMaTES, 
 
 The fifth, sixth and seventh theories are mere hypo- 
 theses, unsupported by either demonstration or observed 
 facts. 
 
 The eighth has been presented to the scientific world 
 through the labors and researches of that eminent geol- 
 ogist and physicist, Dr. James Croll, in his various 
 articles in leading scientific magazines, and lastly, in 
 his grand contributions to the subject under discussion, 
 " Climate and Time " and "Climate and Cosmology." 
 
 The ninth has been maintained by one of the great- 
 est English naturalists, Mr. Alfred Russell Wallace. 
 He combines the theory of Dr. Croll with that of Sir 
 Charles Lyell, and very ably presents his views in 
 1 'Island Life." 
 
 The tenth is a presentation by Dr. Ball, F. R. S., etc., 
 of an interesting demonstration, to the effect that 63 per 
 cent, of solar heat reaches either hemisphere during its 
 summer exposure, and the remaining 37 per cent, during 
 winter exposure. Nothing is added to the Physical 
 Theory of Dr. Croll, nor does the demonstration in any 
 way remove the serious objections which have been 
 urged against Dr. Croll's views. 
 
 The strongest support that has been given to any of 
 the above theories is made by the arguments and de- 
 ductions of Dr. Croll and Mr. Wallace; yet they have 
 failed to produce conviction, for, in a recent work on 
 Geology, the author, after reviewing the various theories 
 as to the cause of the Glacial Period, uses this expression: 
 "This seems to be by far the most probable yet pre- 
 sented."* 
 
 This opinion is directly given upon only one the 
 ninth; but its terms are such that it embraces all. If 
 
 * Elements of Geology, Le Conte, 2d Edition, page 578. 
 
THEIR CAUSES AND VARIATIONS. 11 
 
 % 
 
 the ninth is "by far the most probable/' it would be 
 difficult to fix the degree of probability or improbability 
 of the others. 
 
 The only explanation which can be accepted is one 
 which will admit of definite proof, and will satisfy all 
 the conditions, and not require the distortion of known 
 facts, by forcibly fitting them into arbitrary molds. It 
 must start from universally admitted premises, and in 
 rigid consonance with known laws, correctly interpret 
 the grand eras of climate which have marked the geo- 
 logical history of our globe, and further, it must point 
 out and fully elucidate wherein and why the present 
 climates of our globe differ so radically from those vast 
 secular variations recorded by fossil life aye, more, it 
 must be so general as to be of universal force and ap- 
 plicable to other members of the solar system constituted 
 as our globe. 
 
 In the brief review just made of the principal theories 
 urged by various scientists as causes producing the Ice 
 Age, it was remarked of the first that it was universally 
 admitted as true, and even taught in elementary works 
 on Physical Geography, but that it failed to account for 
 all the facts developed by the Ice Age. This first theory 
 was a decrease in the original heat of the globe, the 
 truth of which is established by a mass of indisputable 
 geological evidence. 
 
 The present conditions are so radically different from 
 any of the eras of climate known to have existed, that 
 the explanation of this range of secular changes becomes 
 the grandest problem in terrestrial physics, and has an 
 important bearing in the solution of existing conditions 
 upon the other planets. 
 
 It is universally admitted that this original heat has 
 been so lost that it is no longer a factor in the surface 
 
12 GEOLOGICAL AND SOLAR CLIMATES, 
 
 temperature of the earth, and that solar energy is now 
 the controlling source of heat. 
 
 There can then be no mistaking the first nor the 
 present condition of the earth as regards its exposure 
 to the only two sources of heat (1) solar and stellar* 
 heat, and (2) resident, internal, or earth heat. There 
 can therefore be no error as to the main features of 
 the problem. 
 
 There must have been two marked eras of climatic 
 control (A) a past era, during which both sources were 
 active; (B) and the present era, in which the greater 
 exterior source only remains, the local and lesser source 
 having been practically exhausted. 
 
 Or, in other words, we have, first, a heated globe having 
 resident in its mass a finite quantity of heat, undergoing 
 loss and exposed to an exterior source of heat and light, 
 which source may be either constant or decreasing in 
 its energy, but so slowly that it may be considered sen- 
 sibly constant during the eras under consideration; 
 second, the same globe deprived of its heat to such an 
 extent that a crust of non-conducting material has 
 formed, the outer surface of which is exposed only to 
 solar heat, and whose climates are entirely controlled 
 thereby. The objects in view being to explain (1) the 
 peculiar uniformity of climates prior to the exhaustion 
 of the first source, and (2) the occurrence of an age of 
 general glaciation in all latitudes prior to the establish- 
 ment of the sole control of the exterior source; (3) the 
 reasons of the differences between heat distribution 
 during geological and present climates. Such explana- 
 tions to be in strict conformity with admitted facts and 
 
 * Stellar heat having the same function as solar heat, and being sensibly 
 a constant of unknown amount but much less than solar heat, need not be 
 separately considered in further discussion of the question. 
 
THEIR CAUSES AND VARIATIONS. 13 
 
 known laws, and without omitting the one nor distorting 
 the other. 
 
 To be explicit we will state that the prime objects are 
 to demonstrate 
 
 1. That in the passage of the earth from an era dur- 
 ing which its climates have been controlled by internal 
 heat into an era during which its climates are controlled 
 by solar heat, eras of uniform climates must have been 
 passed through during which isotherms were independent 
 of latitude. 
 
 2. That before climates could have passed under solar 
 control tlmt an age must occur during which continental 
 areas must be glaciated; and that this stupendous phe- 
 nomenon . occurring before solar climatic control , was 
 also independent of latitude. 
 
 3. That the direct cause of the Ice Age was a com- 
 bination of the remarkable properties, in relation to 
 heat and cold, possessed by the various forms of water. 
 As vapor, in the form of fogs and clouds it prevented the 
 loss or receipt of heat by radiation; as water, by reason 
 of its high specific heat, it retained to the last moment 
 the effective remnant of earth heat; as ice, it assumed a 
 solid form, storing the maximum amount of cold. 
 
 4. To point out in a general way the fallacies of 
 previous attempts to explain geological and present 
 climates. 
 
 The problem will be given in a general proposition, 
 which is capable of demonstration in perfect accord with 
 known laws. 
 
 [This demonstration was first given by the Author in 
 September, 1891, and is reproduced here slightly modified 
 and extended from Vol. VIII of the Transactions of the 
 Technical Society of the Pacific Coast. ] 
 
14 GEOLOGICAL AND SOLAR CLIMATES, 
 
 THE GENERAL PROPOSITION.* 
 
 GIVEN. A heated globe, constituted and circumstanced 
 as the earth, and whose surface temperatures, by reason of 
 internal heat, are above the boiling point of water, to prove 
 that before its surface temperatures can pass under the con- 
 trol of the solar heat (1) that climatic changes must be inde- 
 pendent of latitude, and (2) that the continental areas'^ 
 must be glaciated. 
 
 It will be observed that the surface temperatures of a 
 globe thus situated are entirely controlled by its own in- 
 ternal or earth heat; for between such surface and any 
 external source, a dense cloud of vapor must exist. The 
 fact that direct or radiant heat rays cannot pass through 
 dense fogs and clouds is well known ;t therefore, a globe 
 
 * The proposition here stated is applicable to any planet. It is probable 
 that Mars, Venus and Mercury have passed through periods corresponding 
 to our Ice Age; and that Jupiter, Saturn, Uranus and Neptune have not 
 reached theirs. A study of Jupiter in this connection is particularly in- 
 structive. Phenomena are presented which/, are easily explained by the 
 theory under discussion. See Zenographic A Fragments, London, 1891. 
 Also the author's views in Circulation of the Atmosphere of Planets. Trans. 
 Technical Society of the Pacific Coast, Vol. XI, No. 4, pp. 127-143. 
 
 t There were circumstances protecting certain areas, such as the " Un- 
 glaciated Area," in the basin of the Yellowstone River, in North America. 
 Here vast and continuous lava overflows in Wyoming, Idaho, Oregon and 
 Washington, liberated earth heat; which heat, borne easterly by the gen- 
 eral circulation of the atmosphere, caused the precipitation upon the 
 " Unglaciated Area " to be warm rains instead of snow. To this region 
 the animals of the tertiary period retreated as glacial conditions surrounded 
 them. Here they were protected, and perpetuated their species, and in 
 these regions vast quantities of their remains are found. Mining and 
 Scientific Press, Feb. 14, 1892. 
 
 The easterly projection of the unglaciated area is opposite the correspond- 
 ing projection in the lava overflow. How this simple explanation has 
 escaped the researches of geologists is not known. 
 
 tMaury, Physical Geography of the Sea, 6th Edition, p. 212, et seq. 
 Croll, Climate and Time, p. 60, et seq. Also, Climate and Cosmology, 
 p. 51. 
 
THEIR CAUSES AND VARIATIONS. 15 
 
 thus situated can neither give off, nor receive radiant 
 heat. The peculiar function of solar heat during the 
 existence of appreciable quantities of earth heat was to 
 warm the upper regions of the atmosphere and the outer 
 surface of the clouds exposed to its power, thus partly 
 replacing the heat lost by radiation into space, and 
 causing the store of earth heat to last longer. 
 
 By the conditions of the problem presented, we thus 
 have a globe having resident in its mass a finite quanti- 
 ty of heat exposed to loss only by means of the gradual 
 expansion of water into vapor, and the exposure of this 
 vapor to loss of heat by radiation from its upper surface 
 into space. This vapor would then condense, and as 
 rain, snow or hail, descend all, or part of the way to 
 the earth, receive another increment of heat, and ascend 
 as before. A slow process, but exhaustive in time. 
 
 Thus the property of water to assume three forms, 
 each of which possesses remarkable qualities with re- 
 gard to heat and cold, afforded the only means for ex- 
 hausting the earth heat. As vapor, it possesses the 
 property of storing more heat than any other known 
 substance;* as snow or ice it possesses the property of 
 storing more cold than any other known substance. 
 The function of solar heat, until the exhaustion of 
 earth heat by this process, was simply conservative; 
 it merely warmed the upper layers of the atmosphere, 
 through whose dense vapor its heat lays could not pass. 
 Clouds being more translucent than transcalent, light 
 rays reached the planetary surface prior to heat rays. 
 
 The earth may thus be regarded as having been sur- 
 rounded by a series of spheroidal isothermal shells of 
 mean temperatures. The one next the surface repre- 
 
 * Except hydrogen. 
 
16 GEOLOGICAL AND SOLAR CLIMATES, 
 
 sented a mean temperature of 212 -f- 1 Far. ; t being 
 positive, and proportioned to the greater pressure of the 
 heavier atmosphere existing. Above this isothermal 
 shell were others representing mean temperatures of 90, 
 60, 32, Zero, etc., to x Far., the extreme cold of 
 interplanetary space. Between the two spheroidal 
 iostherms of 32 and x Far., was one which had a 
 mean temperature of 32 y, and equally exposed to 
 both sources of heat. 
 
 That the spheroidal isotherm of 32 Far. was within 
 the sphere of influence of earth heat, is proven by the 
 formation of snow or ice at that temperature, both 
 being the resultant of vapor expanded and raised by 
 earth heat to that height as a minimum. Moreover, 
 vapor would have reached that height as a minimum 
 were solar and stellar heat suspended for a definite 
 period, and the earth absolutely exposed to loss by 
 radiation with no partial return of heat, from exterior 
 sources. 
 
 It therefore follows that the isotherm equally heated 
 by both exterior and interior sources was colder than 
 32 Far. or below that temperature at which snow and 
 ice form. (It is well known that solar energy cannot 
 maintain a temperature as high as 32 Far. except in 
 the lower regions of the atmosphere.) 
 
 The isothermal shells nearest the earth were spheroidal 
 in shape, and by reason of the conditions their surfaces 
 were practically parallel with that of the earth; those 
 most remote from the earth, by reason of solar influ- 
 ences, protruded at the equator and flattened at the poles, 
 so as to be slightly more oblate than the earth; they 
 were sensibly parallel with the spheroidal isotherm now 
 marked by the " snow line." Hence at the equator the 
 direct action of the sun was first felt and established. 
 
THEIR CAUSES AND VARIATIONS. 17 
 
 As the earth heat was a finite quantity exposed to loss, 
 it was in time exhausted. As this loss proceeded, these 
 spheroidal isothermal shells of mean temperatures shrunk 
 in upon the earth, and their contact with its surface 
 marked the zones of corresponding climates prevailing 
 during the dual source of heat. Since these isotherms 
 were independent of equatorial or polar exposure to solar 
 energy their contacts with the planetary surface estab- 
 lished climates independent of equatorial or polar posi- 
 tion, or in other words of latitude; and not until those, 
 whose distance from the surface mainly depended upon 
 solar energy, shrunk to the surface could climates ranged 
 in latitudinal zones be established. As the climates es- 
 tablished by the contact of the isotherms inside of 32 
 y Far. were independent of direct solar heat, they varied 
 from the climates established by solar heat alone; hence 
 the marked difference between climates antedating and 
 succeeding the Ice Age. The isotherms preceding this 
 age were dependent almost entirely upon elevation above 
 sea level, fractures and conductivity of the earth's crust; 
 those succeeding it are dependent upon proximity to the 
 equator, elevation above sea level, and the distribution 
 of heat by ocean currents. 
 
 At the expiration of a period of time T., the earth lost 
 sufficient heat to cause the isothermal shell of 90 Far. 
 to shrink to the surface except at fractures, and a par- 
 ticularly uniform, moist, and highly torrid climate was 
 established, and types of life developed, culminating in 
 the Carboniferous Age. 
 
 The crust cooled sufficiently to permit the demarkation 
 of the continental areas, but the cooling did not pro- 
 ceed to that point which upheaved the massive mountain 
 ranges, nor greatly depressed the ocean areas. There- 
 fore, an -ar-ear of low, flat continents, and shallow hot 
 2 
 
18 GEOLOGICAL AND SOLAR CLIMATES, 
 
 seas followed. The life of that period abundantly shows 
 this condition from one pole to the other, and the pre- 
 vailing temperature is distinctly recorded in the fossil 
 life of the Palaeozoic and Mesozoic Eras. 
 
 Light rays reached the surface prior to this time, as 
 evidenced by the development of visual organs in animal 
 life. 
 
 The greater part of the vapors and gases existing 
 previously in the atmosphere were condensed, and ex- 
 isted upon the surface; the vapors as highly heated 
 oceans, and the gases in various combinations of the 
 mineral and life kingdoms. Now, in the oceans thus 
 formed and further enlarged, there was stored up 
 a vast quantity of the original earth heat, by reason of 
 the high specific heat of water, from which it was not ex- 
 hausted until the last moment; and in this process of 
 exhaustion, it must have maintained the cloud shield, 
 shutting out solar heat until this the last remnant of 
 effective earth heat was exhausted. Not only this, the 
 oceans thus formed had a mean temperature of 90 + z 
 Far., z being a positive increment due to the heat re- 
 ceived from the bottoms and sides of the ocean. Not 
 until the bottoms of the oceans were subjected to a de- 
 gree of cold approximating that to which the continental 
 areas were exposed could the crust be cooled uniformly 
 and reach that degree of uniform thickness and stability 
 suitable to the safety arid comfort of the human race.* 
 
 * Moreover, in cooling the subjection of one pole to glacial and the 
 other to temperate or sub-tropical conditions, as argued by Dr. Croll, 
 would have subjected our planet to very peculiar "cooling strains," as 
 they are termed by foundrymen. Whereas the slow and uniform cooling, 
 as herein described, is productive of maximum thickness, strength and 
 uniformity of crust; and, as will be explained later, this crust was finally 
 shrunk in upon the interior mass by being subjected to the maximum degree 
 of cold to which it can be exposed during the existence _of the sun as a 
 source of heat. 
 
THEIR CAUSES AND VARIATIONS. 19 
 
 At the expiration of the period of time, T', the 
 spheroidal isothermal shell having a mean temperature 
 of 60 Far., similarly shrunk to the surface of the earth, 
 and a corresponding uniformly temperate climate was 
 established. 
 
 The further cooling of the crust caused its shrinkage, 
 and a consequent greater upheaval of those areas most 
 exposed to loss of heat, the continents. This further 
 shrinkage caused the strata formed during the previous 
 eras to be upheaved and fractured, and the lines of de- 
 markation between oceans and continents were thus 
 more strongly accentuated. 
 
 The life developed in the interim evidences an approach 
 to that of the present temperate zones, and its wide dis- 
 tribution demonstrates the complete control of the cli- 
 mates of the globe by internal heat. The isothermal lines 
 were entirely at variance with those established by solar 
 heat, therefore the functions of solar heat remained con- 
 servative of those operating on the surface during this 
 period also. 
 
 The extreme and uniform distribution of fur or hair- 
 covered animals and of the deciduous and coniferous 
 trees of the Ceiiozoic era mark further the control of a 
 source of heat more uniformly distributed than solar 
 heat could possibly be. For reasons previously given, 
 this isotherm also reached continental areas earlier than 
 ocean areas. When the mean temperature of the land 
 was 60 the tepid oceans must have had a mean temper- 
 ature of 60+y Far., y, like z, being positive, and due 
 to increments of earth heat received from the bottom. 
 
 At the expiration of this period T', or at some time, 
 T' a, the isothermal shell of 32 Far. shrunk so as to 
 reach the more elevated portions of the continental 
 areas, and thus established a snow line independent of 
 
 0? THE 
 
 'UNIVERSITY 
 
20 GEOLOGICAL AND SOLAR CLIMATES, 
 
 the influences now establishing and maintaining such 
 snow line. The resulting glaciation was controlled by 
 the same general laws that now exist, only the distribu- 
 tion of heat being independent of latitude, and mainly 
 dependent upon altitude above sea level, glaciation of 
 present tropical and temperate latitudes was as certain 
 to occur as in polar regions. The moment a snow- 
 flake reached the earth which the waning earth heat 
 was unable to melt, the Ice Age was inaugurated; 
 and the conditions were such as to favor its exten- 
 sion until the exhaustion of the store of heat be- 
 neath the oceans and resident in them, by reason 
 of the high specific heat of water. It will be noted 
 here that whenever, in obedience to the expansive 
 force of this waning earth heat, a particle of water was 
 vaporized and made the last round of its circulation, it 
 returned to the earth in that form which stored the 
 maximum degree of cold, or, in other words, in that 
 form which required the maximum amount of solar heat 
 to change. 
 
 From the moment that snow began to accumulate, 
 every remaining vestige of earth heat was available 
 for producing those conditions favorable to glacia- 
 tion, namely, warm seas, dense fogs and cold con- 
 tinental areas; and every unit of solar energy reaching 
 the upper regions of the atmosphere was available for 
 maintaining those favorable conditions.* Glaciation 
 under these conditions would be cumulative until the 
 oceans, exhausted of their heat and lessened in area, 
 
 * The prime objection which is urged against all previous theories is 
 their inadequacy. We here have a perfectly adequate cause resident 
 earth heat to supply evaporation and shut out solar energy, which energy 
 can only act the part of a conservator of the glacial conditions until the 
 exhaustion of earth heat, when its power can be spent in melting glacial 
 ice, and in gradually establishing the present conditions. 
 
THEIR CAUSES AND VARIATIONS. 21 
 
 were no longer able to supply the moisture necessary to 
 completely shroud the earth from direct solar heat. 
 
 At the expiration of the time T", the isothermal shell, 
 having a mean temperature of 32 Far., shrunk in upon 
 the globe, and the oceans were exhausted of their store 
 of heat and their bottoms brought in contact with water 
 having a mean temperature of 31 Far., a temperature 
 approximating that of the ocean depths at present, and 
 of ice in masses. 
 
 The isothermal shell 32 Far. was a spheroid circum- 
 scribing the earth* In shrinking to the earth its inter- 
 sections with the surface were controlled by the eleva- 
 tion of the surface above sea level, and by the local 
 escape of earth heat; elevated equatorial or temperate 
 areas were therefore as much exposed to glaciation as 
 polar lands. (For maximum depth of glaciation see page 
 32.) By reason of the high specific heat of water, this 
 isotherm also reached continental areas prior to reaching 
 ocean areas. 
 
 The crust beneath the ocean, having been protected 
 from loss of heat by the superincumbent water, shrunk 
 to its final shape subsequent to that portion forming conti- 
 nental areas. The ocean bottoms in thus shrinking ap- 
 proximately to their present shape must have been frac- 
 tured, as continental areas had previously been. In this 
 way very considerable increments of earth heat were set 
 free after glaciation had commenced. This process, which 
 is entirely in consonance with known laws, would result 
 in increasing the depth of glaciation, or even in re- 
 establishing it after partial recedence. 
 
 There would also result a complicated series of crust 
 movements as the continents were relieved of pressure 
 by the melting of the ice caps, and the ocean bottoms 
 
22 GEOLOGICAL AND SOLAR CLIMATES, 
 
 subjected to increased pressure by the restoration of 
 water to the oceans.* 
 
 Thus the same forces which, even before the eras we 
 have been considering, must have built up upon the 
 surface of the globe mineral forms of surpassing beauty, 
 only to be destroyed and ground down to give place 
 to vegetable and animal forms of wonderful develop- 
 ment these same forces were called upon to well nigh 
 obliterate every living individual of both kingdoms. 
 The efficiency of their work is attested in every zone of 
 life from the equator to the poles. 
 
 The exhaustion of the residuum of earth heat in the 
 oceans and beneath them could only have been accom- 
 plished by the same means as before, and this exhaus- 
 tion resulted in the preservation of those conditions 
 most favorable to glaciation. When by the chilling of 
 the oceans to about 31 Far. and by the glaciation of 
 continental areas, the air was cleared of obscuring clouds 
 and fogs, the wonderfully uniform series of climates was 
 at an end. 
 
 With the dominion of solar heat there dawned upon 
 our planet an era of climatic zones whose lines sensibly 
 follow parallels of latitude; then also began seasons of 
 spring, summer, autumn and winter, with the varying 
 changes of the earth's annual round. 
 
 The climatic changes during the control of earth heat,, 
 
 * It will again be noted that the isotherms inside of 32 y Far. were 
 maintained by earth heat, and therefore independent of equatorial or polar 
 exposure to solar heat. Consequently their intersections were upon differ- 
 ent lines from those isotherms exterior to 32 y Far., which latter were 
 mainly dependent upon solar heat. It will also be observed that solar 
 heat, when it reaches the lower, denser regions of the atmosphere, is 
 trapped and therefore capable of establishing and maintaining higher tem- 
 peratures than in the upper atmosphere. 
 
THEIR CAUSES AND VARIATIONS. 23 
 
 and within the range of geological research extended 
 over eras: 
 
 1. An era of torrid heat. 
 
 2. An era of tropical heat. 
 
 3. An era of temperate heat. 
 
 4. An era of glacial cold. 
 
 Each merged gradually into the others, but each re- 
 corded its period of existence in unmistakable terms, all 
 shrouded from the direct action of solar heat, and all 
 evidencing by the life produced, the stifling, smothered 
 character of the climate. 
 
 That solar heat was shut out from the surface of the 
 earth during the Ice Age is geologically recorded in the 
 glaciation of the North Temperate Zone over conti- 
 nental areas, where solar energy has removed glacial 
 cold and established in its stead a mean annual tem- 
 perature of 40 Far., and in the torrid zone it has 
 removed glacial cold and established a mean annual 
 temperature of 76 Far., where snow never falls. 
 
 Consequently, in a heated globe, constituted and cir- 
 cumstanced as the earth, exposed to two sources of heat, 
 internal heat and solar heat, before its climates or sur- 
 face temperature can pass under the control of solar heat 
 climatic changes must be independent of latitude and 
 the continental areas must be glaciated. 
 
 A GENERAL COMPARISON OF THE DEMONSTRATION WITH 
 THE FACTS OF GEOLOGY. 
 
 The dawn of the Archaean. Era found the earth a 
 heated globe^merging from an unrecorded and unfathom- 
 greater heat. The crystalline character of the 
 earliest rocks demonstrates the high temperature which 
 prevailed upon the surface at that time. Such being 
 
24 GEOLOGICAL AND SOLAR CLIMATES, 
 
 the temperature of the surface, it is beyond question 
 that the existence of uncombined water upon it was an 
 impossibility, and as vapor it could only shroud the 
 earth in dense clouds. The earth heat was as effect- 
 ually shut in from loss by radiation as was solar heat 
 shut out from reaching the surface. 
 
 As this finite amount of earth heat could only escape 
 by doing work in the expanding of water to vapor, vast 
 eras of time must elapse before the work done could 
 exhaust the available heat. The process of exhaustion 
 was further retarded by two causes: 1st, the heating of 
 the outer layers of the atmosphere by solar heat; and 
 2d, the low conductivity of the strata of the earth itself; 
 consequently the climates of the earth, until the final 
 exhaustion of earth heat, being controlled by a uniformly 
 distributed supply, were of remarkable uniformity. The 
 denudations, faults and fractures 'of its crust set free 
 additional increments of heat but slowly, so that the 
 torrid, tropical and temperate eras Were longer than the 
 frigid era. 
 
 During the existence of sensible quantities of earth 
 heat the oceans must have been heated from the bottom, 
 and cooled at the surface by evaporation. The evapora- 
 tion from the total ocean surface under such conditions 
 would give rise to much more extensive cloud formations 
 than at present. Indeed, the record of temperatures 
 and character of life are such as to warrant nay, even 
 force the conclusion that the whole earth was one vast 
 hothouse, from which solar heat was shut out, and 
 throughout which a uniform temperature was prevalent 
 from pole to pole. 
 
 Solar heat does not penetrate the thinnest cloud; even' 
 a fog through which the form of the sun is distinctly 
 
THEIR CAUSES AND VARIATIONS. 25 
 
 visible shuts out nearly all direct solar heat.* The failure 
 in the past to recognize the climatic influence which the 
 factor earth heat was able to produce, and the endeavor 
 to ascribe to solar energy the climatic conditions exist- 
 ing during the activity of earth heat, has caused all the 
 mystery and error of attempts to explain the climatic 
 phenomena prior to and during the Ice Age. 
 
 Once realize the peculiar influence and domination of 
 earth heat, and these mysteries and errors fade, and the 
 whole system of preglacial and glacial climates becomes 
 simple. 
 
 The function of solar heat during the activity of earth 
 heat could be none other than conservative of the latter; 
 such function it is now performing for the great planets, 
 Jupiter and Saturn, and probably Uranus and Neptune, 
 whose surfaces are shrouded from our view by clouds. f 
 
 * The truth of this fact is easily established by either observation or 
 experiment. At the close of a hot day should a slight cloudiness super- 
 vene, the loss of heat by radiation from the surface is checked; the air at 
 the surface, and the surface, remain at the same temperature, and nature's 
 delicate differential thermometer the deposition or non-deposition of 
 dew records the non-transcalency of clouds, in terms worthy of consid- 
 eration. 
 
 Again, let two delicate thermometers be exposed, one to the air tempera- 
 ture and the other in addition to direct solar rays; the latter will mark the 
 increased temperature due to such exposure. Upon the intervention of a 
 cloud, or even a jet of steam, both instruments will mark the same tem- 
 perature. 
 
 See Physical Geography of the Sea. Maury, 6th ed. r p. 212, et seq. 
 
 Climate and Time, Croll, p. 60, et seq. 
 
 Climate and Cosmology, Croll, p. 51. 
 
 t Astronomers agree that there must exist upon Jupiter a high degree of 
 heat, and yet no refinement of thermometric determinations can detect 
 any more heat from the Jovian surface than should be reflected from the 
 sun. See Young's General Astronomy, page 353; also History of Astronomy 
 During the Nineteenth Century. Clerke, pp. 335-338. 
 
26 GEOLOGICAL AND SOLAR CLIMATES, 
 
 Climatic Facts Established by Fossil Life. 
 
 It would be impossible, in the limits to which it is 
 necessary to restrict this paper, to review the vast array 
 of facts which could be brought forward to demonstrate 
 the perfectly uniform, torrid character of the climates 
 of the globe during the Palaeozoic Era. 
 
 From the 81st degree of north latitude through every 
 range of present climates to the confines of the south 
 frigid zone, the life systems attest the stifling hothouse 
 character of the climate. The species of plant life and 
 animal life, whether of land or marine forms, varied less 
 from the torrid to the frigid zones than corresponding 
 species upon different continents in the same zone do now. 
 Nowhere below the Permian deposits can fossil life be 
 recognized that does not belong to an ultra-tropical type. 
 Such uniformity of temperature is impossible under solar 
 control, and hence can only belong to a climate con- 
 trolled by earth heat. 
 
 In reviewing the temperatures recorded by the fossil 
 life of the Palaeozoic Era, the fact becomes apparent that 
 nowhere upon the surface of the globe during that era 
 were there any zones of temperature. The whole surface 
 was subjected to one universal torrid climate the life 
 developed was uniform in its general character from the 
 Arctic to the Antarctic circle. Under no possible con- 
 ditions could such uniformity of climate have been 
 established and controlled by solar heat alone. Hence 
 during this period earth heat was the controlling source. 
 
 This era merged gradually into the Mesozoic era of 
 tropical heat, during which the forms of life developed 
 into higher types, and their range of distribution demon- 
 strates the still perfect uniformity of climate. One 
 peculiar and significant fact is recognizable in com- 
 
THEIR CAUSES AND VARIATIONS. 27 
 
 paring the land forms with the marine forms of life. 
 The former developed types more suitable to tropical 
 climates, while the latter held more tenaciously to the 
 torrid types, thus proving the more rapid loss of heat 
 by the continents. 
 
 The fossil life of the Cenozoic era corroborates to a 
 remarkable degree the still perfect uniformity of climate. 
 Throughout Greenland, Iceland, Lapland and Spitz- 
 bergen, as well as throughout present temperate and trop- 
 ical zones, a perfectly uniform and temperate climate ex- 
 isted. The flora and fauna of the lower Mississippi 
 valley flourished in those localities in which, during the 
 Paleozoic era, only gigantic Ferns, Lycopods, Calamites 
 and corresponding plant and animal life could be 
 found, and where now only a stunted Arctic life can 
 exist. 
 
 The palseontological evidence of the Mesozoic and 
 Cenozoic eras is equally convincing as to the perfectly 
 uniform tropical climate of the one and temperate and 
 later frigid climates of the other. 
 
 During the latter part of the Tertiary and early Quat- 
 ernary periods identical types of life existed in all parts 
 of Europe, Asia and America and a uniformly temperate 
 climate prevailed over the whole northern hemisphere 
 entirely at variance with the extreme range of tempera- 
 tures now embraced in that half of the globe. 
 
 The control of the waning earth heat was simply 
 dying out, and had reached that stage in which it was 
 
28 GEOLOGICAL AND SOLAR CLIMATES, 
 
 no longer .able to maintain the high temperatures of 
 previous eras.* 
 
 The evidence that the high specific heat of water held 
 the last available remnant of earth heat, and thus per- 
 petuated its control of climates, is beyond dispute, as 
 presented by the conditions culminating in the Ice Age. 
 
 Whatever may be the doubts as to the actual date of 
 the Ice Age., there is no disputing the fact that the evi- 
 dences establishing the culmination of that Age are 
 found above, or since the Tertiary, and beloiv or before 
 the Modern Era. . 
 
 * The author is aware that this statement is at variance with the opin- 
 ion of many Geologists of high repute, as may be seen from the following 
 quotations: "It is evident that the idea of connecting the phenomena of 
 the internal heat of the globe with terrestrial climates, whether of the 
 present or of past geological ages, must be entirely abandoned, as it has 
 been, by most writers on this subject. The hypothesis cannot be allowed 
 to stand as even one of the possible theories of climatic change." The 
 Climatic Changes of later Geological Times. Whitney, p. 261. 
 
 " The first theory brought forward to account for glaciation was that 
 the earth, having been originally in a fiery state, had in cooling passed 
 from a condition of universal warmth to a more and more frigid state, 
 until the present conditions were attained. This is the least tenable of 
 all theories, for it neglected the now evident fact that there had been 
 changes from cold to warmth and back again to cold. However, as it was 
 invented before the existence of glacial periods was suspected, it long 
 commanded a general assent, and was the opinion that held the ground 
 until near the middle of this century." Glaciers. Shaler & Davis, p. 70. 
 
 The physicists who have held that earth heat was a cause of the Ice Age 
 are Prof. E. Frankland, F. K. S., Prof. A. Woeikof and SJtartorius von 
 Walterhausen. Not one of the three, however, seems to have had a clear 
 conception of all the facts and conditions although their views were in the 
 main sound. 
 
 The author hopes to extend the views held by these writers and to show 
 that the whole range of climates as recorded by fossil and existing life is 
 capable of correct interpretation, in accordance with known laws, and 
 without the intervention of suppositions and assumptions. And more- 
 over, to base his deductions upon a general plan applicable to any planet 
 and capable of explaining conditions prevalent upon other planets, notably 
 upon Jupiter and Mars. 
 
THEIR CAUSES AND VARIATIONS. 29 
 
 Between these two periods there is abundant evidence 
 from every climate, from every zone of present life, that 
 the continents were glaciated. 
 
 Europe and Asia, North and South America, Africa 
 and Australia,* all present glacial strise, boulder deposits, 
 and other marked evidences of glaciation at the same 
 period, just antedating the Modern Era, or during the 
 Quaternary period. 
 
 When we examine the evidence found in one of the 
 present climatic zones, this change of climate from an 
 ultra-torrid successively to a torrid, tropical, temperate, 
 and, lastly frigid character, is not only very marked, 
 but is everywhere the same. 
 
 * To those interested in a verification of this very wide distribution of 
 glaciation, the following short list of authorities is recommended: 
 
 Asia. The Great Ice Age (Giekie); Note on the Glaciation of parts 
 of the Valleys of Jhelan and Scind Eivers, in the Himalaya Mount- 
 ains of Kashmere, Lat. 34 N. (Capt. A. W. Sleff), F. G. S.; Jour. 
 Geol. Soc,, London, vol. xlvi, p. 66; Mem. Geol. Survey of India, vol. 
 xxii, also vol. xiv; Kecord Geol. Survey of India, Nov., 1880; Jour. Asiatic 
 Society, Bengal, xxxvi, p. 113; Brit. Association Report, 1880; Text Book 
 of Geology, A. Giekie, LL. D., etc., p. 911. 
 
 Europe. The European Glacial Literature is too extensive to mention. 
 
 America. The Ice Age in North America (Wright); U. S. Geological 
 Reports; State Geological Reports of Ohio, Kentucky, Pennsylvania, New 
 York, Minnesota, Nebraska, Colorado, Illinois, etc.; Virginia, Am. Jour. 
 Sci., vol. vi, p. 371; California, Am. Jour. Sci., vol. iii.p. 325, vol. x, p. 26. 
 
 South America. Geological Sketches, Agassiz, p. 154, et seq.; Geol. and 
 Physical Geog. of Brazil (Prof. Ch. Fred. Hartt), pp. 22, 28-9, 469-70, 
 490, 558. 
 
 Africa. Geol. of South Africa (Stow); Quart. Journ. Geol. Soc., Lon- 
 don, vols. xvii and xviii. 
 
 Australia and New Zealand. Climate and Time (Croll), p. 295; Am. 
 Jour. Sci., vol. 32, third series, p. 224; Proc. Linnsean Soc., N. S. W., May, 
 1886; Prestwich's Geol., vol. ii, p. 467; Rep. Brit. Assn., 1881, p. 742. 
 
 "The shrunken or vanished ice of mountain ranges is indeed 
 equally characteristic of the Himalaya, the Lebanon, the Alps, the Scan- 
 dinavian chain, the great chains of North and South America, and of other 
 minor ranges and clusters of mountains." Ramsay, Quart. Jour. Geol. 
 Soc., 1862, p. 204. 
 
30 GEOLOGICAL AND SOLAR CLIMATES, 
 
 Upon the establishment of solar heat in the control 
 of surface temperatures, we find the isotherms entirely 
 at variance with those ante-dating the Ice Age. We 
 find also strong corroboration in the lines of retreat of 
 the continental ice caps. These lines are sensibly par- 
 allel with the isotherms established by solar heat, prov- 
 ing that solar heat was the cause of the disappearance 
 of glacial conditions. 
 
 These facts distinctly prove the totally different source 
 and distribution of heat before and. since the Ice Age, 
 and that upon the inauguration of climates controlled 
 by solar energy, an obliteration of the conditions left 
 upon the dying out of earth heat set in. Along that 
 zone most exposed to solar energy conditions and life 
 corresponding to the tropical conditions of Cenozoic 
 times have been established; along those zones mod- 
 erately exposed to solar energy the newly established 
 conditions are analogous to the universally temperate 
 climate of the latter Tertiary and early Quaternary 
 periods; whilst in those zones least exposed to solar en- 
 ergy a removal of glacial conditions is yet in progress.* 
 
 Wherever fossil life has been developed the order of 
 climates, as thus recorded has been: First, torrid; 
 second, tropical; third, temperate; fourth, frigid; and 
 fifth, the life appropriate to the zone of solar climate 
 irrespective of that existing previous to the Ice Age. 
 The same order is true for any portion of either tem- 
 perate zone; under the equator the order of climates 
 
 * Many geologists are misled by the greater modification of tropical 
 drift by sub-aerial agencies. Having been longer exposed to such agencies, 
 greater modifications are to be expected. The apparent improbability of 
 tropical glaciation seems to deter many scientists from believing that such 
 glaciation could ever have occurred, yet the same scientists will accept the 
 fact that fossil life establishes the existence of tropical or even torrid con- 
 ditions within the polar circles during past ages. 
 
THEIR CAUSES AND VARIATIONS. 31 
 
 has been the same, except a return to tropical conditions 
 and life.* 
 
 In the North frigid zone this same order of climates 
 has been found, except that there has been no change 
 from the conditions left upon the dying out of earth 
 heat; in other words, solar energy has not removed 
 glacial cold in those regions least exposed to its action. 
 
 The removal of glacial conditions has been less in the 
 Antartic than in the Arctic regions, partly from causes 
 pointed out by Maury, and more fully treated by Dr. 
 Croll. This removal has also been subjected to varia- 
 tions due to the mild astronomical influences ascribed 
 by Adhemar, Croll, Ball, Drayson and others, as suffi- 
 cient to produce glaciation. 
 
 These astronomical causes undoubtedly must have pro- 
 duced slight secular variations in the relative exposures 
 of the two hemispheres to solar heat but they have not 
 been demonstrated to be of sufficient influence to produce 
 glaciation, and. in no way could they sensibly affect 
 climates prior to the establishment of the control of 
 solar heat. (See page 41.) 
 
 The distribution of heat, prior to the Ice Age, as 
 recorded by fossil life, being entirely at variance with 
 that now found, and being entirely independent of 
 proximity to, or distance from, the equator, distinctly 
 proves that climates were established and maintained 
 independently of solar heat, and hence belong to the only 
 other source, viz., earth heat. 
 
 It is also evident that under no possible conditions 
 could solar energy maintain a torrid, tropical, temperate 
 and lastly glacial climate over the whole range of the 
 present zones of climates, and that this uniform distri- 
 
 *See Geological Sketches, Agassiz, p. 154, etseq. Also Physical Geography 
 and Geology of Brazil, Prof. Ch. Fred. Hartt, pp. 22, 28, 29, 217, 469, 470. 
 
32 GEOLOGICAL AND SOLAR CLIMATES, 
 
 bution of heat prior to and during the glaciation of the 
 globe was due to an evenly distributed supply from a 
 constantly and uniformly decreasing source. 
 
 Moreover, the wide distribution of glaciation over the 
 present temperate and torrid zones is a distinct proof of 
 the exclusion of solar heat from these regions during 
 glaciation. Under no possible circumstances could tem- 
 perate North America, Europe and Asia and tropical 
 South America have been glaciated unless these regions 
 were shut out during glaciation from that solar energy, 
 which when admitted has removed glacial conditions. 
 
 Glacial dispersion followed one of two general laws: 
 First, the great centers or belts from which dispersion 
 took place in apparent disregard of the slope of the 
 ground were areas most exposed to cyclonic activity and 
 resulting precipitation. Second, minor centers of dis- 
 persion (or local glacial dispersion) were elevated lands, 
 subjected to uniform precipitation'.* 
 
 Since glacial conditions in the northern hemisphere 
 were removed from southerly towards northerly latitudes, 
 the gradients were increased southerly and decreased 
 northerly from lines of maximum glaciation. Glacial 
 transportation was likewise modified. The reverse of 
 these directions prevailed in the southern hemisphere. 
 
 Glaciated areas have been partly relieved of their loads 
 of ice at rates and times proportional to solar exposure, 
 and upon lines parallel with present mean annual iso- 
 therms. Wherever remnants of the continental ice sheets 
 of the Ice Age yet rest, this retreat is still in progress 
 from the same cause. 
 
 The ascription of great elevations above sea level dur- 
 
 * See the author's views in Physical and Geological Traces of Permanent 
 Cyclone Belts. Trans. Technical Society of the Pacific Coast, Vol. VIII, 
 No. 1, June, 1891. 
 
THEIR CAUSES AND VARIATIONS. 33 
 
 ing the Ice Age is natural, and such apparent greater 
 elevation is due to tivo causes during this period, whilst 
 due to only one cause during previous eras. As the 
 surface of the earth became subjected to a temperature 
 of 31 Far. under the oceans, and a corresponding 
 temperature under the continental ice caps, contraction 
 and consequent elevation were continued as before; and 
 as snow was piled up upon the continents, water was 
 withdrawn from the oceans; for each million square 
 miles of continental ice cap three hundred feet thick a 
 corresponding three million square miles of ocean was 
 lowered one hundreed feet. The continental ice caps 
 already approximately known were too vast not to have 
 lowered the sea level to a marked degree. 
 
 The apparent general depression after the Ice Age is 
 as natural. By the melting of the greater portion of 
 the ice caps, and the evaporation of vast inland seas, 
 the sea was approximately restored to the level existing 
 prior to the Ice Age, thus causing an apparent sinking 
 of the land. 
 
 The great difference between climatic conditions prior 
 to and since the Ice Age is very marked around inland 
 seas and basins without drainage. Lake Bonneville and 
 Lake Lahontan, in the United States, and the greater area 
 once occupied by the Caspian and other seas, evidence 
 the superior dampness and rainfall antedating the Ice 
 Age. During the control of earth heat the oceans were 
 heated to their bottoms, and furnished moisture enough 
 to keep these great depressions full of water and to sup- 
 port a dense life upon now desert areas. The dry air of 
 the modern era has not only absorbed the water in these 
 vast lakes, and restored it to the oceans, but vaster areas 
 have been converted into deserts by the unequal distri- 
 bution of heat and moisture under solar control. 
 3 
 
34 GEOLOGICAL AND SOLAR CLIMATES, 
 
 PALEOZOIC GLACIATION. 
 " Glacial Periods." 
 
 It is probable and may be regarded as a fact that upon 
 certain of the oldest and highest mountains, glaciation 
 was inaugurated during the Paleozoic Era, to slowly dis- 
 appear by the gradual setting free of earth heat by vast 
 fractures of the crust or to remain as local glaciation until 
 the Ice Age. Isolated glacial deposits of this nature which 
 were independent of solar exposure readily account for 
 the early "Glacial Periods," which were evidently local 
 phenomena antedating the Ice Age. It is neither logi- 
 cal nor reasonable to interpret the finding of evidences 
 of early local glaciation into a Glacial Period, for local 
 glaciations are found now in the Alps and upon certain 
 peaks of the Sierra Nevada, and even in the torrid zone, 
 but they by no means establish the present existence of 
 a Glacial Period. 
 
 Evidences of glaciations antedating the Ice Age are 
 wholly of a mechanical nature namely, the transport- 
 ation of boulders, striae, etc. No corroborative evidence 
 of fossil life of Arctic habits has been found. This is 
 particularly the case of marine fauna and flora, which 
 may be held as the only indisputable evidence of an Ice 
 Age. 
 
 Granting that the evidences found be sufficient to estab- 
 lish Palaeozoic glaciations, the absence of fossils of an 
 Arctic type proves such glaciations to have been local 
 and possibly of short duration, for had such glaciation 
 been general and of long duration both plant and 
 animal life would have been modified into temperate 
 and Arctic types, as occurred later when general glacia- 
 tion ensued. 
 
 It is apparent that the isotherm 32 Far. could have 
 shrunk for a short period to the tops of mountains 
 
THEIR CAUSES AND VARIATIONS. 35 
 
 and that glaciers could have formed and coursed their 
 way into a subtropical growth below; and that these 
 conditions would be removed by the setting free of 
 earth heat with the consequent rise in temperatures. 
 
 These changes followed too closely or were too limited 
 in area to permit the evolution of forms of continental 
 life adapted to temperate and Arctic conditions. 
 
 Palaeozoic glaciations in 110 way conflict with the 
 demonstration herein given they are really corobora- 
 tive of the other facts advanced to prove that prior to 
 the Ice Age solar heat was shut out from the surface. 
 For the evidences of Palaeozoic glaciation occur in tem- 
 perate and tropical latitudes adjacent to fossil life indi- 
 cative of high temperatures. Early glaciations were 
 dependent only upon elevation, and latitude did not in- 
 fluence their occurrence in any way whatever, and 
 whether in Norway or India these glacial conditions were 
 coexistent with tropical life at a lower elevation and 
 equally independent of latitude. 
 
 When the crust became too thick and non-conducting 
 to yield a sufficient supply of heat to hold mean tem- 
 peratures at a higher degree of heat than 32 Far. this 
 isotherm shrunk to the surface only to be removed 
 by solar heat. Since the position of this isotherm was 
 independent of latitude its intersections with the surface 
 depended only upon elevation, and as the continents lost 
 their heat more rapidly than oceans, the latter were the 
 last to fall to 32 Far. 
 
 As in previous eras torrid, tropical and temperate life 
 had existed in Spitzbergen, France and Brazil independ- 
 ent of the latitudes of these countries, so too were glacial 
 conditions equally independent of latitudes. But in the 
 removal of glacial conditions the isotherms of solar cli- 
 mates were necessarily followed. 
 
36 
 
 Thus the Ice Age marks the date at which the climates 
 of the globe passed from the control of earth heat to 
 that of solar heat. The great specific heat of water re- 
 tained in the oceans, the energy necessary to maintain 
 the cloud shield shutting out solar heat until both land 
 and ocean areas could be equally cooled and contracted, 
 thus ensuring the maximum degree of thickness and 
 stability to the crust. The mysteries of geological 
 climates, interpreted by known laws, applicable alike to 
 all members of the solar system, develop thus into a 
 system beautiful in its simplicity. 
 
 Once realize that the surface temperatures of the globe 
 were at one era in the past too high, by reason of inter- 
 nal heat, to permit water to remain upon the surface, 
 and the peculiar properties possessed by the various 
 forms of water and their relations to heat and cold, and 
 follow out these facts to their natural and logical con- 
 clusion, and the whole mystery of geological climates 
 clears up and becomes simple. 
 
 MATHEMATICAL CALCULATIONS AS TO THE DURATION OF 
 EARTH HEAT. 
 
 It would not be proper to make the foregoing inter- 
 pretation of the cause of geological climates without 
 briefly referring to the various mathematical calculations 
 which have been made by high authorities, and which 
 reach conclusions materially differing from the deduc- 
 tions herein presented. 
 
 The arguments of Sir Wm. Thomson* and others, to 
 the effect that internal or earth heat could not have 
 affected the climates of the globe, by reason of the non- 
 
 * Phil. Mag. (4), Vol. XXV, pp. 1-14. Trans. Koyal Soc. Edin., Vol. XXIII. 
 Influence of the Earth's Secular Heat upon Climates. Hopkins, Jour. 
 Geol. Soc., Vol. VIII. 
 
THEIR CAUSES AND VARIATIONS. 37 
 
 conductivity of a comparatively slight thickness of crust, 
 are not conclusive. These arguments are based upon: 
 
 1 . An erroneous assumption of the manner in which 
 heat is lost by a planet, upon which there exists an 
 atmosphere and a fluid possessing the physical prop- 
 erties of water. 
 
 2. No account is taken in these calculations of the 
 heat set free by denudations, etc. 
 
 3. The conservative action of active exterior sources 
 is not considered. 
 
 1. To assume that in a molten or nearly molten 
 planet heat was lost by direct radiation from the heated 
 surface, is to assume a mode of loss that could not 
 possibly occur with the constitution of our planet, 
 nor with one possessing a constitution generally similar. 
 
 At the period assumed as the starting point of these 
 calculations the earth's crust was just forming from the 
 molten state. At this period, which has undoubtedly 
 existed, all uncornbined water must have been evapor- 
 ated, and must have existed as an enshrouding cloud, 
 shutting out solar heat and shutting in earth heat. Our 
 planet at this period must have presented an appearance 
 similar to that now presented by Jupiter, whose avail- 
 able internal heat has evidently not yet been exhausted, 
 and upon whose surface evaporation must be kept up by 
 internal heat. 
 
 The loss of internal heat by a globe constituted as our 
 planet, must proceed, not by the radiation and loss of 
 heat directly into space, but by the performance of 
 work in the expansion of water to vapor, the exposure 
 of the upper or cold surface of the partly condensed 
 vapor to loss of heat by radiation into space. 
 
 The existence of a non-transcalent cloud shield is 
 geologically recorded in most unmistakable terms, as 
 
38 GEOLOGICAL AND SOLAR CLIMATES, 
 
 previously explained, by the maintenance of eras of 
 tropical, temperate and frigid climates from pole to pole 
 irrespective of latitude; by the glaciation of areas over 
 which solar energy, when not thus shut out, was capable 
 of removing glacial conditions and establishing much 
 warmer climates; also by the contrast of geological 
 climates with solar climates, one independent of, and 
 the other mainly dependent upon, latitude. 
 
 Thus the loss of heat by the crust must have pro- 
 ceeded with great slowness; and the crust in thus cool- 
 ing was, by the laws of cooling solids, made as thick as 
 possible. 
 
 2. The non-conductivity of this cooling crust was a 
 cause of the long, instead of a cause of short duration of 
 the internal heat, for when too thick to yield up its heat 
 by conductivity, additional increments were but slowly 
 set free by denudations, faults and fractures. The volume 
 of heat thus set free may be partly grasped when it is 
 considered that no portion of the crust can be reached 
 that is not built up of denuded materials. Heat im- 
 prisoned by a non-conducting crust is more certain of 
 liberation by denudation than if the crust were com- 
 posed of strata having the conductivity of beaten silver. 
 
 The assumption that the low conductivity of the crust 
 was a cause of the short duration of earth heat as a con- 
 trolling factor is exactly contrary to the actual tendency 
 of such low conductivity. 
 
 3. From the cold outer surface of the cloud envelop 
 heat would radiate much more slowly than from the 
 more highly heated surface beneath. Indeed, there 
 is every reason to assume that this upper surface may 
 have been partly composed of fine crystals of ice, 
 as cirrus clouds may now be. Upon this upper 
 surface, whatever may have been its condition, was 
 
THEIR CAUSES AND VARIATIONS. 39 
 
 received every thermal unit of heat reaching our globe 
 from exterior sources from its development to the cul- 
 mination of the Ice Age. What calculation has con- 
 sidered this single factor? which, for aught we know, 
 may have been but little less than the original available 
 store. To what consideration is any discussion which 
 omits this factor entitled? 
 
 Having properly assumed a temperature which would 
 necessitate the evaporation of all uncombined water and 
 its suspension above the heated surface, a scientist 
 should follow the results to their legitimate and logical 
 conclusion, and not neglect the existence of a con- 
 dition necessarily coexistent with those assumed. 
 
 The removal of the enshrouding clouds need not be 
 assumed; such removal was blazed upon the globe in 
 broad zones of climate and life which only solar energy 
 could maintain. These lines are as distinctly different 
 from those written by earth heat as daylight is from 
 darkness. 
 
 When this removal did take place the fact was graven 
 upon our planet by the melting of the massive glaciers 
 deposited during and before such removal, and by the 
 establishment of the existing conditions. 
 
 All calculations and discussions omitting these three 
 factors must reach illogical and erroneous conclusions. 
 The omission of a single one would be fatal, and entitle 
 the result to no farther consideration, and justifies the 
 cynical view that " There is something fascinating about 
 science. One gets such wholesale returns of conjecture 
 out of such trifling investment in facts." 
 
40 GEOLOGICAL AND SOLAR CLIMATES, 
 
 ASTRONOMICAL CAUSES AND THEIR INFLUENCE. 
 
 We will now consider the effect of astronomical causes. 
 Dr. Croll has elaborately discussed the variations in solar 
 exposure to which the two hemispheres of our planet 
 have been and are subjected.* 
 
 The distinguished Astronomer Koyal of the Dublin 
 Observatory, Dr. Ball, has shown that 63% of the gross 
 solar energy received by either hemisphere reaches it 
 during summer and the remaining 37% during winter.f 
 High authorities, both before and since these publica- 
 tions, have discussed various phases of these influences, 
 as well as offered remarkable and un verifiable hypotheses 
 regarding the temperature of space, solar energy, and 
 the heat absorptive power of a solar envelope. J It is 
 not necessary to attempt a discussion or elaboration of 
 these views. Should the interpretation herein rendered 
 be correct, it follows that variations in the distance from 
 or degree of solar energy could not have directly affected 
 the surface temperatures of the globe prior to the cul- 
 mination of the Ice Age, and that only since that age 
 could these slight variations have acted, except in a 
 conservative way. It is unquestionable that for many 
 years past the temperature of the northern hemisphere 
 has risen more rapidly than the southern. This condi- 
 tion is proved not only by correct deductions from actual 
 conditions and laws, but by observation. This is also 
 recorded geologically by the greater removal of glacial 
 conditions in the northern hemisphere although in 
 both this removal is yet in progress. 
 
 In a globe wrapped in a mass of vapor by reason of 
 
 * Climate aud Time, Climate and Cosmology, 
 t The Cause of an Ice Age, chapters 5 and 6. 
 I Nature, May 1891; S. E. Bishop. 
 
THEIR CAUSES AND VARIATIONS. 41 
 
 evaporation maintained at the surface by its own heat 
 and condensed upon the outer surface of the spheroidal 
 cloud envelope, it is immaterial so far as surface tem- 
 peratures are concerned, to what degree of outside heat 
 it may be subjected. The only possible effects of varia- 
 tions in the distance from, or intensity of the exterior 
 heat source being to influence the duration of the interior 
 supply and the distance therefrom at which cloud con- 
 densation takes place. 
 
 In a globe thus enshrouded the same order of surface 
 temperatures would follow, whether revolving in the orbit 
 of Venus or that of Neptune the actual influences being 
 the greater rate of loss in the remoter position, the more 
 rapid succession of .geological climates, and the greater 
 
 Mrrwmr-aJi n %t*-'^& &r>&L*3wy**^cL-&^7 : %Jt' CT 
 
 tune necessary for the, establishment of solar climatic 
 control. Could the earth have been removed during the 
 Archaean Age to the orbit of Jupiter without disturbing 
 other conditions, no change could have occurred in the 
 order of succeeding geological climates prior to the Ice 
 Age. The rate of receipt of solar energy would have been 
 in the ratio of (5.2) 2 :1; and the actual retardation of loss 
 would have been in this ratio, as also the rate of estab- 
 lishment of solar climatic control; the crust would have 
 cooled quicker, and therefore have been thinner and less 
 stable than at present. 
 
 The observed movements in the cloud envelope of 
 Jupiter present phenomena warranting the belief that 
 his atmosphere is non-transcalent.* In this particular 
 it resembles the clouded atmosphere of the earth; and 
 indicates a condition analogous to that of the earth in 
 pre-glacial ages. The smaller planets by reason of their 
 lesser masses have lost their available resident heat. 
 
 * Circulation of the Atmosphere of Planets. Trans. Technical Soc. of 
 the Pac. Coast, Vol. IX, No. 5; pp. 136-143. 
 
42 GEOLOGICAL AND SOLAR CLIMATES, 
 
 Their atmospheres have become cleared and are both 
 translucent and transcalent. Their surfaces can be 
 observed, and their volumes and densities calculated 
 with a reasonable degree of exactness. In the cases of 
 the larger planets observations are confined to the surface 
 of their spheroidal cloud envelopes, and hence to these 
 planets are ascribed volumes and densities varying 
 abnormally from those whose actual volumes can be 
 measured. The satellites of Jupiter possess much greater 
 densities than that ascribed to the great planet were it 
 possible to measure the actual volume of his enshrouded 
 mass this apparent anomaly would be in whole or in part 
 removed. 
 
 Not knowing the surface temperatures, the exact com- 
 position of the atmospheres, nor the dimensions of the 
 planetary masses, the distances to which the cloud 
 envelopes of Jupiter, Saturn, Uranus and Neptune may 
 be expanded, are yet matters of conjecture. Whatever 
 is known of these planets corroborates the interpretation 
 herein rendered of the record of the geological climates 
 of the earth.* 
 
 THE ESTABLISHMENT OF SOLAR CLIMATES. 
 
 At the culmination of the Ice Age the snow line was 
 much lower than at present, and elevated landsf at all 
 latitudes were deeply glaciated; the seas were intensely 
 cold. It is evident that since the culmination of the Ice 
 Age and in the establishment of the present climates 
 there has been a great rise in temperatures in the tropi- 
 
 * For a further discussion of the conditions prevalent upon Jupiter see 
 Circulation of the Atmosphere of Planets, previously quoted. 
 
 t Except hot or warm lava covered areas, and the protected or " uii- 
 glaciated areas " to the eastward of such lava overflows. (See page 44 
 and note (t) page 14.) 
 
THEIR CAUSES AND VARIATIONS. 43 
 
 cal, temperate and sub-frigid zones. There is also in- 
 disputable evidence that this rise in temperature is yet 
 in progress. This accession of heat must therefore be 
 accounted for by the correct application of laws and 
 forces now acting, and it is not necessary to go outside 
 of these known laws and forces to render a correct in- 
 terpretation of the establishment and maintenance of 
 the zones of climate now existing. 
 
 It will be observed that when the oceans were ex- 
 hausted of their heat and the lands deeply glaciated, the 
 crust was shrunk in upon the interior mass by being 
 uniformly chilled down to the lowest temperature to 
 which a planet, upon which water and an atmosphere 
 exist, can be subjected. The atmosphere was then 
 cleared of clouds and heat rays from exterior sources 
 permitted to reach the planetary surface. At once 
 these rays began to be changed into dark heat rays, 
 particularly those from water, and the trapping of 
 heat ensued; from this date a general rise in tempera- 
 tures must follow from the accession of heat from ex- 
 terior sources, until checked within the moderate limits 
 hereafter outlined. 
 
 The trapping process thus inaugurated is independent 
 of the actual amount of heat received whether from solar 
 or stellar sources. 
 
 Were it possible for the now pent-up internal heat to 
 raise the temperature of the oceans, the crust at the 
 bottom of the oceans, and under the polar ice caps to 
 a mean temperature of say 68 degrees Far., the accession 
 of heat from exterior sources would be shut off, as in 
 early Quaternary times, by dense clouds; the exterior 
 would be again shrunk by glacial conditions, the air 
 cleared as before and heat from exterior sources in what- 
 ever amounts it then reached the surface would be 
 trapped as succeeded the Ice Age. 
 
44 GEOLOGICAL AND SOLAR CLIMATES, 
 
 This action must in turn take place upon any planet 
 upon which water and an atmosphere resembling ours 
 exist. The rate at which a planet acquires heat from 
 exterior sources is dependent upon the power of its at- 
 mosphere to trap heat; very slight variations in the at- 
 mospheric constituents producing great variations in 
 heat trapping power. 
 
 Orbital distance being only a function of the amount 
 received and not of the trapping process, this rise in 
 temperature is as certain to follow in one position as 
 another. 
 
 By thus being subjected to the maximum shrinking- 
 strains the weakest portions of the crust were ruptured. 
 The lava ejected from these ruptures was spread out 
 over the weak areas in successive layers of a few dozen 
 feet in thickness until the added strength reached that 
 belonging to thousands of feet of solid rock.* 
 
 To digress a moment 
 
 These lava overflows evidently performed another im- 
 portant function. The heat set free by each successive 
 layer could not have been lost by radiation into space, 
 for the enshrouding clouds had not yet been removed. 
 The air and clouds caught this heat and bearing it east- 
 wardly in their general course caused warm rains instead 
 of snow to be precipitated upon the adjacent region. In 
 this way the " unglaciated area " escaped glaciation; in 
 
 * The Columbian Lava Plains of North America aggregate some 150,000 
 square miles; the Deccan Lava Plains of India cover an almost unbroken 
 plain 200,000 square miles in area. No Geologists ascribe these lava over- 
 flows to an earlier date than the Tertiary; the author could find no reason 
 to assign the Columbian Lava Plain to so early a period, and strong 
 reasons to assign the continuance of the flow to the later Quaternary; 
 of the Deccan Plain he is unable to speak. (See Trans. Geological Society 
 of Australasia, vol. i, part vi, p. 162, note. Also Mining and Scientific 
 Press, Feb. 6th, 1892. 
 
THEIR CAUSES AND VARIATIONS. 45 
 
 this area are the "bad lands" of Dakota, whose topo- 
 graphy distinctly shows that sub-aerial denudation, and 
 not glacial ice formed the controlling features. In this 
 area are the great deposits of tertiary fossil life, in per- 
 fect form uiicrushed by the mighty tread of the glaciers 
 which surrounded them on all sides, except to the west. 
 From areas such as these went forth the life that sur- 
 vived the glacial winter. 
 
 That the isotherm marked by glacial ice is yet slowly 
 retreating upward is recorded not only by tradition 
 and history but geologically and physically, as observed 
 by every scientist who has studied existing glaciers.* 
 
 This retreat is a positive proof of either a decrease in 
 precipitation on the tributary areas, a rise in tempera- 
 ture, or both of these agencies acting conjointly. There 
 is no evidence to show that a decrease in precipitationf 
 is synchronously taking place over the sub-frigid, tem- 
 perate and tropical regions of both hemispheres, as is 
 the retreat of glaciers; and there are positive and active 
 causes in force which have affected, and are yet affecting 
 an increase in temperature. We must therefore con- 
 clude that this rise in the isotherm marking glacial ice 
 
 * Climatic changes indicated by Glaciers. 
 
 Prof. I. C. Russell, Ain. Geologist, May, 1892, vol. ix, No. 5. In ad- 
 dition to the very extensive list of authorities there quoted by Prof. 
 Russell, see also Report of The British Ass'n. 1881, p. 742. 
 
 Life of Agassiz, Vol. II, pp. 717 to 729 and pp. 743 to 747. 
 
 t At the culmination of the Ice Age evaporation reached its minimum, and 
 hence precipitation was also at a minimum. Since that Age evaporation has 
 slowly increased; the amount of moisture in the atmosphere being depend- 
 ant upon its temperature, this amount has also increased. The aggregate 
 amount of evaporation and the aggregate amount of precipitation is 
 slowly increasing, and has the moderate limit fixed by natural laws for in- 
 crease of mean temperature. Mars appears to have progressed further in 
 this mean condition than the earth. The smaller mass partly accounts 
 for this. 
 
46 
 
 is due primarily, if not entirely, to an accession of heat. 
 
 It has been demonstrated that at the culmination of 
 the Ice Age, much colder conditions existed than at 
 present. It now remains to explain the conditions act- 
 ing to bring about existing climates. Upon the exhaus- 
 tion of the last available remnant of earth heat left in 
 the oceans by reason of the high specific heat of water 
 the supply of vapor maintaining the cloud envelop was 
 shut off, and solar heat permitted to reach the planetary 
 surface. 
 
 That direct solar rays are converted into obscure or 
 dark heat rays by contact with the planetary surface, 
 and that the atmosphere of our planet is more transca- 
 lent to the former than to the latter, has been fully 
 demonstrated by Tyndall,* although slightly modified 
 by Buff.f 
 
 However small may be the difference between the 
 transcalency of the atmosphere to direct solar rays and 
 to the dark rays into which the direct are converted, a 
 gradual rise in temperature must follow. This rise must 
 follow w r hether solar energy be constant or slowly de- 
 creasing, the rise being due not to the actual amount of 
 heat received, but to the difference between the rate of 
 receipt and the rate of loss. 
 
 The great increase of mean surface temperatures in 
 equatorial, temperate and sub-tropical areas being due 
 to this small but positive difference between the rates of 
 receipt and loss; as has just been shown, this action is 
 yet in progress. 
 
 These deductions are radically at variance with the 
 
 * Archives des Sciences, vol. v, p. 293. Proc. Koyal Soc., vol. xiii, 
 p. 160. 
 
 t Archives des Sciences, Berne, vol. Ivii, p. 293, et seq. 
 
THEIR CAUSES AND VARIATIONS. 47 
 
 opinion of high authorities on meteorology, as may be 
 seen from the following quotation: " It is evident that 
 our planet, considered as a whole, and on the average of 
 many years, loses all the heat that it receives from the 
 sun, but all the details of this process have not yet been 
 worked out.*" 
 
 The author is unable to find any facts to sustain this 
 view^-all tend to refute it. The trapping of heat by 
 vapors and gases of the atmosphere the gradual retreat 
 of glaciers in both hemispheres and the vast rise in 
 temperatures since the culmination of the Ice Age all 
 conclusively tend to corroborate the deductions just 
 reached namely, that the mean surface temperatures 
 of the globe have been and are yet rising from the 
 trapping of heat. 
 
 It does not follow that this rise has an indefinite or 
 excessive limit, as the oceans become warmer they are 
 cooled by giving off more vapor. This vapor, when 
 partly condensed into clouds, intercepts solar heat in 
 the upper atmosphere, and the intense white of the 
 upper surface of clouds reflects more heat into space 
 than the darker planetary surface beneath .^~ 
 
 The vast store of cold in the continental ice sheets 
 has been greatly exhausted; there yet remains the vaster 
 store in the ice cold depths of the oceans, the conserv- 
 ative influence of which cannot be estimated; for besides 
 the difficulties of heating water from the surface down- 
 
 *Dr. Cleveland Abbe, U. S. Meteorological Bureau. Am. Jour, of 
 Science, May, 1892, vol. xliii, p. 364. 
 
 t The albedo of Jupiter is 0.62; that of Mars, 0.26, of the moon 0.174. 
 It will be observed that the planets distinctly shrouded in clouds have 
 high reflective powers; those planets and satellites not shrouded -have very 
 low powers. Venus, in this respect, seems to have a partially obscured 
 atmosphere, her albedo being 0.50. 
 
48 GEOLOGICAL AND SOLAR CLIMATES, 
 
 wards, there yet remains the cooling effect of surface 
 evaporation. There is thus presented the extreme slow- 
 ness of the methods by which vast changes are wrought. 
 Here are agencies whose results are so slight as not to be 
 detected by thermometric methods yet recording their 
 effects in grand eras of climates throughout the earth. 
 
 The planet Mars is particularly interesting, having a 
 mass less than one-ninth (^ T ) that of the earth. His 
 loss of internal heat occurred ages before that of the 
 earth; therefore, Mars has been a heat-gathering body 
 longer than the earth, and enjoys a milder general tem- 
 perature,* although that planet receives less than half 
 the heat and light received by the earth Jupiter is in 
 a condition which our geological history proves the earth 
 to have passed through; Mars is in a condition towards 
 which the earth is gradually tending. f 
 
 It is now a simple matter to trace the steps by which 
 glacial conditions were removed and zones of climate 
 established. 
 
 Solar energy first established its control in that zone 
 most exposed to its power namely, the torrid zone. 
 From this zone glacial conditions were first removed, 
 and this removal continued north and south upon lines 
 parallel with present isotherms. 
 
 In considering the astronomical causes, and the phys- 
 ical results thereby brought about, it was argued that 
 these causes tended to heat the northern hemisphere 
 more rapidly than the southern. Dr. Croll and other 
 physicists, have so fully discussed this question that there 
 remains but little to.be added. 
 
 * General Astronomy. Young; p. 337. 
 
 t Venus presents a condition which suggests that she may be partly 
 shrouded in clouds, shutting out solar heat, just as the thermal equator 
 of the earth is thus partly protected by the equatorial cloud ring. 
 
THEIR CAUSES AND VARIATIONS. 49 
 
 The prime reason, however, seems to have been 
 omitted, which is simply this, the northern hemisphere, 
 containing so large a predominance of land area, was 
 more easily warmed than the southern. This unequal 
 heating once inaugurated would establish currents both 
 of air and water tending to perpetuate this action, rein- 
 forced as it is by geographical and cosmical agencies. 
 
 When, by this gradual accession of heat, conditions 
 and temperatures resembling those existing prior to the 
 Ice Age, were re-established, we find these new condi- 
 tions restricted to latitudinal belts sensibly parallel with 
 the equator, but modified by elevation and ocean cur- 
 rents; whereas the corresponding pre-glacial climates 
 were independent of latitude. 
 
 By the trapping of solar heat a gradual rise in tem- 
 perature was inaugurated at that period, when by the 
 exhaustion of the earth heat, left in the oceans, the 
 enshrouding clouds were removed. Then, and not until 
 then, do we find the removal of conditions shutting out 
 solar heat written in zones of life belting the earth. In 
 these new zones of climate there have been developed 
 higher, nobler types of life, and with the birth of the 
 seasons there was ushered in upon the earth that Light 
 which is developing Psychozoic Life. 
 
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