But if this be granted, we must then inquire, What was its nature? and what its extent? The former is quite easily answered: the latter problem is still somewhat beyond our reach.
As to its character, the evidence is very plain. It was a veritable cataclysm of some sort: it deals with great changes of land and water surface. If the geological succession is but a hoary myth, and if we find countless modern living species of plants and animals mixed up in all the "older" rocks, we cannot ignore these in a rational and unprejudiced reconstruction of the science. But, ignoring these, we must remember that even the Tertiary and post-Tertiary deposits are absolutely world wide, and are packed with fossils of living species. Not a continent and scarcely a country on the globe but contains great stretches of these deposits, laid down by the sea where now the land is high and dry. The sea and land have practically shifted places over all the globe since Man and thousands of other living species left their fossils in the rocks. It is only the stupendous magnitude of these changes which has made our scientists reluctant to admit the possibility of such a catastrophe.
With the myth of a life succession dissipated, a broad view of the fossil world cannot fail to convince the mind of the reality of some such cosmic convulsion, and convince it with all the force of a mathematical demonstration. Great groups of animals have dropped out of sight over all the continents, and their carcasses have been buried by sea water where we now find high plateaus or mountain ranges. Ignoring completely the abundant fossils in the so-called "older" rocks, and fixing our attention entirely on the Tertiary and Pleistocene beds that are acknowledged to be closely connected with the human race and the modern world, we still have a problem in race extinction alone that appalls the mind. The mammoth, rhinoceros and mastodon, together with "not less than thirty distinct species of the horse tribe," as Marsh says, all disappear from North America at one time, and the most ingenious disciple of Hutton and Lyell has been puzzled to invent a plausible explanation. But when we consider that at this same "geological period" similar events were occurring on all the other continents—the huge ground-sloths (megatheriums) and glyptodons in South America; "wombats as large as tapirs," and "kangaroos the size of elephants" in Australia; the mammoth and woolly rhinoceros in Eurasia; together with an enormous hippopotamus, as far as England is concerned, to say nothing of those great bears, lions and hyenas, with a semi-tropical vegetation, all disappearing together at the same time, or shifting to the other side of the world—it becomes almost like a deliberate insult to our intellectual honesty to be approached with offers of "explanations" based on any so-called "natural" action of the forces of nature. But when, in addition to all this, we consider the fact that those human giants of the caves of Western Europe were contemporary with the animals mentioned above, and disappeared along with them at this same time, while mountain masses in all parts of the world crowded with marine forms of the so-called "older" types positively cannot be separated in time from the others, it becomes as certain as any other ordinary scientific fact, like sunrise or sunset, that our once magnificently stocked world met with some sudden and awful catastrophe in the long ago; and is it in any way transgressing the bounds of true inductive science to correlate this event with the Deluge of the Hebrew Scriptures and the traditions of every race on earth?
We have already seen how Dana supposes two such events, one at the close of the "Palaeozoic age," and the other at the close of the "Mesozoic," merely to account for the astonishing disappearance of species at these periods when the fossils are arranged in taxonomic order; but if we once admit such an event with Man and all the other species contemporary with one another, where shall we limit its power to disturb the land and water and churn them all up together, leaving the present simply as the ruins of that previous world? The fact is, the current Geology is wholly built up from the Cambrian to the Pleistocene on the dogmatic denial that any such catastrophe has occurred to the world in which Man lived, for one such event happening in our modern homogeneous world is enough to make the whole pretty scheme found in our text-books tumble like a house of cards. Like the patient and exact observations of the Ptolemaic astronomers, which accumulated volumes of evidence contradicting their own theories, and which in the hands of Copernicus and Galileo, Kepler and Newton, sealed the doom of astronomical speculation and laid the foundations of an exact science of the heavens; so have the indefatigable labors of thousands of geologists accumulated evidence which strikes at the very foundation of the current Uniformitarianism, and casts a pall of doubt over every conclusion as to how or when any given deposit of the "older" rocks was produced.
Here we must leave the question for the present. The possibility of such a world-wide catastrophe, which might account for the major part of the geological changes, needs no apology here. The slightest disturbance of the nice equilibrium of our elements would suffice to send the waters of the ocean careering over the land; and in the abundance of astronomical causes competent for such disturbance we cease to regard such an event as necessarily contrary to "natural law." The possibility of such a thing no competent scientist now denies; it is the problem of recovery from such a disaster which makes the perplexity. But incredible or not as the latter may be regarded, I claim to have established a perfect chain of scientific argument proving a world-wide catastrophe of some sort since Man was upon it. But this fact, if once admitted, strikes at the very foundation of the current science, and bids us readjust our theories from this view-point. The venerable scheme of a life succession becomes only the taxonomic or classification series of the world that existed before this disaster, and it becomes the business of our science to find out how many and what deposits were due to this event, and what were accumulated during the unknown period of previous existence. Those of us who wish to speculate can then let our imaginations have free play as to the uncounted ages before that event; but the "phylogenic series" as a rational scientific theory is in limbo forever. Inductive geology, therefore, deals not with the formation of a world, but with the ruins of one; it can teach us absolutely nothing about origins.
The latter problem lies across the boundary line in the domain of philosophy and theology, and to these systems of thought we may cheerfully leave the task of readjustment in view of the facts here presented. A few disconnected thoughts along these lines I have ventured to insert here, not strictly as a part of my purely scientific argument, but as an appendix.