Age of the earth as determined by the date of the glacial epoch.—Professor A. Winchell, by a most careful examination of the probable relative lengths of geological periods, arrived at the conclusion that the time which elapsed since the beginning of the glacial epoch is to the time which has elapsed since the solidification of the earth’s surface as 1 to 250.[[55]] According to the eccentricity theory of the cause of the glacial epoch, that epoch began 240,000 years ago; consequently this makes the time since solidification took place 60,000,000 years, a period which agrees roughly with that deduced from denudation, and is so far presumptive evidence of the truth of that theory of the cause of the glacial cold.
Testimony of Biology.—The time required for the variation and modification of organic forms has, Mr. Alfred R. Wallace states, been generally considered to require an even longer series of ages than might satisfy the demands of physical geology. This is a point, however, on which I am not qualified to venture an opinion. I shall simply refer to the views held by our highest authorities on the subject.
Referring to Professor Huxley’s anniversary address to the Geological Society in 1870, where he shows that almost all the higher forms of life must have existed during the Palæozoic period, Mr. Wallace says: “Thus, from the fact that almost the whole of the Tertiary period has been required to convert the ancestral Orohippus into the true horse, he, Professor Huxley, believes that, in order to have time for the much greater change of the ancestral ungulata into the two great odd-toed and even-toed divisions (of which change there is no trace even among the earliest Eocene mammals), we should require a large portion, if not the whole, of the Mesozoic or Secondary period. Another case is furnished by the bats and whales, both of which strange modifications of the mammalian type occur perfectly developed in the Eocene formation. What countless ages back must we, then, go for the origin of these groups, the whales from some ancestral carnivorous animal, and the bats from the insectivora! And even then we have to seek for the common origin of carnivora, insectivora, ungulata, and marsupials at a far earlier period; so that, on the lowest estimate, we must place the origin of the mammalia very far back in Palæozoic times.”[[56]]
“If the very small differences,” says Professor Huxley,[[57]] “which are observable between the Crocodilia of the older Mesozoic formations and those of the present day furnish any sort of approximation towards an estimate of the average rate of change among the Sauropsida, it is almost appalling to reflect how far back in Palæozoic times we must go before we can hope to arrive at that common stock from which the Crocodilia, Lacertilia, Ornithoscelida, and Plesiosauria, which had attained so great a development in the Triassic epoch, must have been derived.
“The Amphibia and Pisces tell the same story. There is not a single class of vertebrated animals which, when it first appears, is represented by analogues of the lowest known members of the same class. Therefore, if there is any truth in the doctrine of evolution, every class must be vastly older than the first record of its appearance upon the surface of the globe. But if considerations of this kind compel us to place the origin of vertebrated animals at a period sufficiently distant from the Upper Silurian, in which the first Elasmobranchs and Ganoids occur, to allow of the evolution of such fishes as these from a vertebrate as simple as the Amphioxus, I can only repeat that it is appalling to speculate upon the extent to which that origin must have preceded the epoch of the first recorded appearance of vertebrate life.”
“If the theory be true,” says Mr. Darwin, “it is indisputable that before the lowest Cambrian stratum was deposited long periods elapsed—as long as, or probably far longer than, the whole interval from the Cambrian age to the present day; and that during these vast periods the world swarmed with living creatures.”[[58]]
In referring to the abundant and well-developed fauna of the Cambrian period, Sir Andrew C. Ramsay remarks:[[59]] “In this earliest known varied life we find no evidence of its having lived near the beginning of the Zoological series. In a broad sense, compared with what must have gone before, both biologically and physically, all the phenomena connected with this old period seem, to my mind, to be quite of a recent description; and the climates of seas and lands were of the very same kind as those that the world enjoys at the present day—one proof of which, in my opinion, is the existence of great glacial boulder beds in the Lower Silurian strata of Wigtonshire, west of Loch Ryan.”
Professor Haeckel remarks that “Darwin’s theory, as well as that of Lyell, renders the assumption of immense periods absolutely necessary. If the theory of development be true at all, there must certainly have elapsed immense periods, utterly inconceivable to us.”
In reference to the foregoing, Mr. Wallace says:[[60]] “These opinions, and the facts on which they are founded, are so weighty that we can hardly doubt that, if the time since the Cambrian epoch is correctly estimated at 200,000,000 of years,[[61]] the date of the commencement of life on the earth cannot be much less than 500,000,000; while it may not improbably have been longer, because the reaction of the organism under changes of the environment is believed to have been less active in low and simple than in high and complex forms of life, and thus the processes of organic development may for countless ages have been excessively slow.”
I think it must now be perfectly evident that the facts both of geology and of biology are utterly irreconcilable with the theory that the sun’s heat was derived from the condensation of its mass by gravitation; and that the mistake in regard to geological time has been committed by the physicist, and not by the geologist. The grounds upon which the geologists and the biologists found the conclusion that it is more than 20 or 30 millions of years since life began on the earth are far more certain and reliable than the grounds upon which the physicist concludes that the period must be less. The only real ground that the physicist has is that according to the theory which he holds of the origin of the sun’s heat a longer period is not possible. This might be considered good evidence were no other theory possible; but there is another theory, which accords with all the facts, and consequently has a strong presumption in its favour.