CHAPTER X

CHANGE OF CLIMATE

Another great general fact about the fossil world may be stated about as follows:

=All of the fossils= (save a very few of the so-called "Glacial Age," and they admit of other easy explanation) =give us proofs of an almost eternal spring having prevailed in the Arctic regions, and semi-tropical conditions in north temperate latitudes; in short give us proofs of a singular uniformity of climate over the globe which we can hardly conceive possible, let alone account for.=

The proofs of this are almost unnecessary, as this subject of climate has been pretty well discussed of late years. And it was the overwhelming evidence on this point which forced Lyell and so many others to decide against the theory of Croll, which called for a regular rotation of climates, for they said that the fossil evidence was wholly against such a view. Howorth has given an admirable argument on this point in Chapter XI of his second work on the Glacial Theory[68] and to it I would refer the reader for details which I have not the space to reproduce here.

This author first remarks:

"The best thermometer we can use to test the character of a climate is the flora and fauna which lived while it prevailed. This is not only the best, but is virtually the only thermometer available when we inquire into the climate of past geological ages. Other evidence is always sophisticated by the fact that we may be attributing to climate what is due to other causes; boulders can be rolled by the sea as well as by sub-glacial streams, and conglomerates can be formed by other agencies than ice. But the biological evidence is unmistakable; cold-blooded reptiles cannot live in icy water; semi-tropical plants, or plants whose habitat is in the temperate zone, cannot ripen their seeds and sow themselves under arctic conditions.... We may examine the whole series of geological horizons, from the earliest Palaeozoic beds down to the so-called Glacial beds, and find, so far as I know, no adequate evidence of discontinuous and alternating climates, no evidence whatever of the existence of periods of intense cold intervening between warm periods, but just the contrary. Not only so, but we shall find that the differentiation of the earth's climate into tropical and arctic zones is comparatively modern, and that in past ages not only were the climates more uniform, but more evenly distributed over the whole world."

Without attempting to follow through the whole series of formations we may note a few characteristic statements of the text-books. Thus Dana says of the Cambrian:

"There was no frigid zone, and there may have been no excessively torrid zone."

While of the Silurian coral limestones of the Arctic regions he says:

"The formation of thick strata of limestone shows that life like that of the lower latitudes not only existed there, but flourished in profusion."[69]

Howorth thus quotes Colonel Fielden, the Arctic explorer, regarding the fossil Sclerodermic corals of the Silurian, widely distributed in the Arctic regions:

"These undoubted reef-forming corals of the Silurian epoch were just as much inhabitants of warm water in northern latitudes at that period as are the Sclerodermata of to-day in the Indo-Pacific and Atlantic oceans.... These corals were forms of life which must have been tropical in habits and requirement."

In fact coral limestones of the Carboniferous system are the nearest known fossiliferous rocks to the North Pole, and from the strike of the beds must underlie the Polar Sea. In the words of Howorth, "Coal strata with similar fossils have occurred all round the Polar basin ... and may be said, therefore, to have occupied a continuous cap around the North Pole."[70]

Again I quote from Howorth regarding the Mesozoic rocks:

"This very widespread fauna and flora proves that the high temperature of the Secondary era prevailed in all latitudes, and not only so, it pervaded them apparently continuously without a break. There is no evidence whatever, known to me, that can be derived from the fauna and flora of Secondary times, which points to any period of cold as even possible. There are no shrunken and stunted forms, and no types such as we associate with cold conditions, and no changes evidenced by intercalated beds showing vicissitudes of life."

The following is from Nordenskiold, as quoted by Howorth, and refers to the whole geological series:

"From what has been already stated it appears that the animal and vegetable relics found in the Polar regions, imbedded in strata deposited in widely separated geological eras, uniformly testify that a warm climate has in former times prevailed over the whole globe. From palaeontological science no support can be obtained for the assumption of a periodical alternation of warm and cold climates on the surface of the earth."[71]

And now we have the equally positive language of A. R. Wallace:

"It is quite impossible to ignore or evade the force of the testimony as to the continuous warm climate of the North Temperate and Polar Zones =throughout Tertiary times=. The evidence extends over a vast area both in space and time, it is derived from the work of the most competent living geologists, and it is absolutely consistent in its general tendency ... Whether in Miocene, Upper or Lower Cretaceous, Jurassic, Triassic, Carboniferous or Silurian times, and in all the numerous localities extending over more than half the Polar regions, we find =one uniform climatic aspect of the fossils=."[72]

Of course in all this I am taking the various kinds of fossils in the traditional chronological order. But I shall presently show on the best of authority that Man existed in "Pliocene" or perhaps "Miocene times," and in view of such an admission we have, even from the standpoint of current theory, a vital, personal interest in this question of climate. Let us take, then, the following from James Geikie, the great champion of the Glacial theory, on the climate of the Arctic regions at this part of the =human epoch=:

"Miocene deposits occur in Greenland, Iceland, Spitzbergen, and at other places within the Arctic Circle. The beds contain a similar (similar to the "most luxuriant vegetation" of Switzerland) assemblage of plant-remains; the palm-trees, however, being wanting. It is certainly wonderful that within so recent a period as the Miocene, a climate existed within the Arctic regions so mild and genial as to nourish there beeches, oaks, planes, poplars, walnuts, limes, magnolias, hazel, holly, blackthorn, logwood, hawthorn, ivy, vines, and many evergreens, besides numerous conifers, among which was the sequoia, allied to the gigantic _Wellingtonia_ of California. This ancient vegetation has been traced up to within eleven degrees of the Pole."[73]

According to Dana and other American geologists the "Glacial Period" is only a variation intervening between the warm Tertiary and the equally warm "Champlain Period," and it was during the latter that the mammoth, mastodon, etc., roamed over Europe, Asia, and America. Of the climate then indicated, when all acknowledge that Man was in existence, this author says:

"The genial climate that followed the Glacial appears to have been marvelously genial to the species, =and alike for all the continents, Australia included=. The kinds that continued into modern time became dwindled in the change wherever found over the globe, notwithstanding the fact that genial climates are still to be found over large regions."[74]

In his "Geological Story Briefly Told," he uses even stronger language:

"The brute mammals reached their maximum in numbers and size during the warm Champlain Period, and many species lived then which have since become extinct. Those of Europe and Britain were largely warm-climate species, such as are now confined to warm temperate and tropical regions; and only in a warm period like the Champlain could they have thrived and attained their gigantic size. The great abundance of their remains and their condition show that the climate and food were all the animals could have desired. They were masters of their wanderings, and had their choice of the best."[75]

"The genial climate of the Champlain period was _abruptly_ (italics Dana's) terminated. For carcasses of the Siberian elephants were frozen so suddenly and so completely at the change, that the flesh has remained untainted." (Id. p. 230.)

I quite agree with this author that the evidence is conclusive as to the climate and food being "all the animals could have desired," and that they must have "had their choice of the best." But it seems to me that in following out their theory these authors have not left the poor creatures very much to choose from. For as the inevitable result of their theory in arranging the plants as well as the animals in chronological order according to the percentages of living and extinct forms, they have already disposed of, and consigned to the "early" Tertiaries, etc., all the probable vegetation on which these animals lived, and thus have nothing left on which to feed the horse and bison, rhinoceros and elephant, etc., away within the Arctic Circle, except the few miserable shrubs and lichens which now survive there.

But this strange, inconsistent notion of Dana's that the so-called Glacial phenomena lie in between the warm Tertiary and the equally warm "Champlain period," is easily understood as the survival of the notion, so tenaciously held even later than the middle decades of the nineteenth century, that Man was =not= a witness of any of the great geological changes. When the evidence became overwhelming that Man lived while the semi-tropical animals roamed over England, the "Glacial period" still remained as a sort of buffer against the dangerous possibility of extending the =human= period back any further. I am not aware that this venerable scientist ever became quite reconciled to the idea of "Tertiary Man," though in his "Manual" he mentions a few evidences in favor of this now almost universally accepted opinion.

As for the real teachings of the Drift phenomena there is no need of explanation here. At the very most they are confined to a quite limited part of the northern hemisphere, there being no trace of them in Alaska, nor on the plains of Siberia, where now almost eternal frosts prevail.[76] In fact they are practically confined between the Rocky Mountains and the Missouri River on the west, and the Ural Mountains on the east; and with a little common sense infused into the foundation principles of the science we will cease to be tormented with a "Glacial Nightmare." Much of the Drift phenomena with the raised beaches are certainly =later= events than most of the other geological work, but are inseparably connected with the general problem in their explanation. Even from the ordinary standpoint, I am not aware that the elaborate argument of Howorth has even been satisfactorily answered. Indeed, I feel almost like saying that this writer's various contributions to the cause of inductive geology mark the beginning of the dawn.

Hence it may suffice here to merely call attention to the great simplicity introduced into this vast complexity of the glacialists, by the positive assurance of this author that the "Drift period" and the Pleistocene =end together=, and join onto the modern; or perhaps I ought rather to say that the so-called Glacial phenomena lie in between the true fossil world and our modern one.

"Thus, in regard to the Pleistocene mammals, the view is now generally accepted that, in every place where they have been found in a contemporary bed, that bed underlies the till, and is therefore pre-glacial. As in other places, so here (Scotland), teeth and bones of mammals have occurred in the clay itself; but in all such cases they occur sporadically and as boulders. As Mr. James Geikie says, 'They almost invariably afford marks of having been subjected to the same action as the stones and boulders by which they are surrounded; that is to say, they are rubbed, ground, striated, and smoothed.'"[77]

And again:

"=The Pleistocene fauna, so far as I know, came to an end with the so-called Glacial age.=" (Id. p. 463.)

From a recent notice in _Nature_[78] it would seem that even Dr. H. Woodward, of the British Museum, supports this general view in his "Table of British Strata," by the statement that the glacial deposits contain =only derived fossils=.

But this is such a decided simplification of the problem of climate that I am utterly at a loss to understand how any one can still cling to the complex and highly artificial arrangement of numerous "interglacial" periods, to account for a few bones of mammals or a few pockets of lignite; and how they can even place between the "Glacial period" and our times the "genial Champlain period," with it, as Dana says, "=abruptly terminated=," and becoming "=suddenly= extreme as of a single winter's night." Howorth, in the latter part of the chapter already quoted from (pp. 460-478), gives a good review of this subject of intermittent climates, and strongly supports his contention that the =stratigraphical evidence= all points to the fact that the Pleistocene forms are always older than the Drift-beds, and where the flora and fauna of the Pleistocene occur in the Drift, they do so only as boulders; that, in fact, as he says in his Preface, "The Pleistocene Flood ... =forms a great dividing line= in the superficial deposits," separating the true fossil world from the modern.

I have hardly the space to repeat here my argument about the extremely fanciful way in which geologists classify the various members of the Tertiary group and the Pleistocene. And yet I must say a few words. I have tried to show the utter nonsense of the common custom of classifying these beds according to the percentage of living and extinct forms which they contain, when the real fact is that the number and kinds of the ancient life-forms which have survived into the modern era is a purely fortuitous circumstance, being limited solely to those lucky ones which could stand the radical change from a tepid water or a genial air to the ice and frosts which they now experience, to mention only one circumstance of that cosmic convulsion which we now know to have really intervened between that ancient world and our own. =YET IT IS ON SUCH EVIDENCE ONLY= that these Pleistocene forms are separated from the Tertiaries, or that the Tertiaries themselves are classified off--at least as far as the invertebrates and the plants are concerned. No one claims that the so-called Glacial beds can be sharply distinguished from other deposits on purely mechanical make-up. Indeed, I am strongly of the opinion that very many Archaean soils, totally unfossiliferous themselves, and resting on unfossiliferous rocks, have been assigned to the "Glacial age," merely because their discoverers did not know what else to do with them. When beds contain fossils, the latter are the one and only guide in determining age; but in view of the purely arbitrary character of this method of classifying off the Tertiary and post-Tertiary rocks, I do not see where we are going to =draw the line= when we once admit that the post-Tertiary beds contain only "derived fossils." It seems to me truly astonishing that shrewd reasoners, like Howorth and Dr. Woodward, have not seen the dangerous character of this precedent which they have admitted. For with that marvelous climate of all geological time continuing right up to that fatal day when it was "abruptly terminated," and the mammoth and his fellows were caught in the merciless frosts which now hold them, the percentage of all the lucky forms of life, plants, invertebrates, or mammals, which could stand such a change and "persist" into our modern world, must be =utterly nonsensical as a test of age= even from their standpoint.

In resuming the main argument of this chapter, I need only summarize by saying that the evidence is conclusive that all geological time down to this sharp "dividing line" was characterized by a surprisingly mild and uniform climate over all the earth. The modern period is characterized by terrific extremes of heat and cold; and now little or nothing can exist where previously plant and animal life flourished in profusion.

This radical and world-wide change in climate, therefore, demands ample consideration when seeking a true induction as to the past of our globe. That it was no gradual or secular affair, but that the climate "became =suddenly= extreme as of a single winter's night," the Siberian "mummies" are unanswerable arguments. =That it occurred within the human epoch= all are now agreed.

FOOTNOTES:

[68] "The Glacial Nightmare and the Flood," pp. 426-479.

[69] "Manual," pp. 484, 524-5.

[70] Op. cit., pp. 434-5.

[71] Id., p. 45.

[72] "Island Life," pp. 182, 195-6; "Nightmare," pp. 455-6.

[73] "Historical Geology," p. 76.

[74] "Manual," p. 997.

[75] p. 225, Edition of 1875.

[76] See Dana's "Manual," pp. 945, 977; also "The Glacial Nightmare," pp. 45-2, 511, etc.

[77] "Great Ice Age," p. 129; "Nightmare," p. 473.

[78] See _Nature_ April 11, 1901, p. 560.