Imperfection of the Geological Record.

Therefore, this objection is no objection at all. The facts of this character—and they are numerous—belong to that class of evidence which I have called indifferent. That is to say, they may be no direct support to the doctrine of Evolution, but they are perfectly capable of being interpreted in consistency with it. There is another order of facts of the same kind, and susceptible of the same interpretation. The great group of Lizards, which abound so much at the present day, extends through the whole series of formations as far back as what is called the Permian epoch, which is represented by the strata lying just above the coal. These Permian lizards differ astonishingly little—in some respects—from the lizards which exist at the present day. Comparing the amount of difference between these Permian lizards and the lizards of the present day, with the prodigious lapse of time between the Per- page 20 mian epoch and the present age, it may be said that there has been no appreciable change.

But the moment you carry the researches further back in time you find no trace whatever of lizards nor of any true reptile whatever in the whole mass of formations beneath the Permian. Now it is perfectly clear that if our existing palaeontological collections, our existing specimens from stratified rock, exhaust the whole series of events which have ever taken place upon the surface of the Globe, such a fact as this directly contravenes the whole theory of Evolution, because that postulates that the existence of every form must have been preceded by that of some form comparatively little different from it. Here, however, we have taken in consideration that important fact so well insisted upon by Lyell and Darwin—the imperfection of the geological record. It can be demonstrated as a matter of fact that the geological record must be incomplete, that it can only preserve remains found in certain favorable localities and under particular conditions; that it must be destroyed by processes of denudation, and obliterated by processes of metamorphosis—by which I mean that beds of rock of any thickness crammed full of organic remains may yet, either by the percolation of water through them or the influence of subterranean beat (if they descend far enough toward the centre of the earth), lose all trace of these remains and present the appearance of beds of rock Conned under conditions in which there was no trace of living forms. Such metamorphic rocks occur in formations of all ages, and we know with perfect certainty when they do appear that they have contained organic remains, and that those remains have been absolutely obliterated.

One of the most striking proofs with which I am acquainted of the defects of the geological record—and I insist upon it the more because those who have not attended to these matters are apt to say to themselves, "It is all very well, but when you get into difficulty with your theory of Evolution you appeal to the incompleteness and the imperfection of the geological record," and I want to make it perfectly clear to you that that imperfection is a vast fact, which must be taken into account with all our speculations or we shall constantly be going wrong.

You will all see that singular series of tracks which is copied to its natural size in the large diagram hanging up here, which I owe to the kindness of my friend Professor Marsh, with whom I had the opportunity recently of visiting the precise locality in Massachusetts in which these tracks occur. I am, therefore, able to give you my own testimony, if needed, that they accurately represent the state of things which we saw. The valley of the Connecticut is classical ground for the geologist. It contains great beds of sandstone, covering many square miles, and which present this peculiarity, that they have evidently formed a part of an ancient sea shore, or, it may be, lake shore, and that they have been sufficiently soft for a certain period of time to receive the impressions of whatever animals walked over them, and to preserve them afterward in exactly the same way as such impressions are at this very moment preserved on the shores of the Bay of Fundy and elsewhere. We have there the tracks of some gigantic animal (pointing to the diagram) which walked on its hind legs. You see the series of marks made alternately by the right foot and by the left foot; so that from one impression to the other of the three-toed feet on the same side is one stride, and that stride, as we measured it, is six feet nine inches. I leave you, therefore, to page 21 form an impression of the magnitude of the creature which must have walked along the ancient shore, and which made these impressions.

Now, of such impressions there are untold thousands upon these shores. Fifty or sixty different kinds have been discovered, and they cover vast areas. But up to this present time not a bone, not a fragment, of any one of the great creatures which certainly made these impressions has been found; and the only skeleton which has been met with in all these deposits to the present day, though they have been carefully hunted over, is one fragmentary skeleton of one of the smaller forms. What has become of all these bones? You see we are not dealing with little creatures, but animals that make a step of six feet nine inches; and their remains must have been left somewhere. The probability is that they have been dissolved away, and absolutely lost.

I have had occasion to work at series' of fossil remains of which there was nothing whatever except the casts of the bones, the solid material of the bone having been dissolved out by percolating water. It was a chance in this case that the sandstone happened to be of such a constitution as to set, and to allow the bones to be afterward dissolved out.

Had that constitution been other than what it was, the bones would have been dissolved, the beds or sandstone would have fallen together, become one mass, and not the slightest indication that the animal had existed would have been discovered.

I know of no more striking evidence than this fact affords from which it may be concluded, in the absence of organic remains, that such animals did exist. I believe that having the right understanding of the doctrine of Evolution on the one hand, and having a just estimation of the importance of the imperfection of the geological record on the other, would remove all difficulty front the kind of evidence to which I have thus adverted, and this appreciation allows us to believe that all such cases are examples of what I may here call, and have hitherto designated, negative or indifferent evidence—that is to say, they in no way directly advance the theory of Evolution, but they are no obstacle in the way of our belief in the doctrine.