[D] Psalm civ.
The enormous accumulations of sediment on the still thin crust of the earth in the Laurentian period—accumulations probably arranged in lines parallel to the directions of disturbance already indicated—weighed down the surface, and caused great masses of the sediment to come within the influence of the heated interior nucleus. Thus, extensive metamorphism took place, and at length the tension becoming too great to be any longer maintained, a second great collapse occurred, crumpling and disturbing the crust, and throwing up vast masses of the Laurentian itself, probably into lofty mountains—many of which still remain of considerable height, though they have been subjected to erosion throughout all the extent of subsequent geological time.
The Eozoic age, whose history we have thus shortly sketched, is fertile in material of thought for the geologist and the naturalist. Until the labours of Murchison, Sedgwick, Hall, and Barrande had developed the vast thickness and organic richness of the Silurian and Cambrian rocks, no geologist had any idea of the extent to which life had reached backward in time. But when this new and primitive world of Siluria was unveiled, men felt assured that they had now at last reached to the beginnings of life. The argument on this side of the Question was thus put by one of the most thoughtful of English geologists, Professor Phillips: "It is ascertained that in passing downwards through the lower Palæozoic strata, the forms of life grow fewer and fewer, until in the lowest Cambrian rocks they vanish entirely. In the thick series of these strata in the Longmynd, hardly any traces of life occur, yet these strata are of such a kind as might be expected to yield them.... The materials are fine-grained or arenaceous, with or without mica, in laminae or beds quite distinct, and of various thicknesses, by no means unlikely to retain impressions of a delicate nature, such as those left by graptolites, or mollusks, or annulose crawlers. Indeed, one or two such traces are supposed to have been recognised, so that the almost total absence of the traces of life in this enormous series is best understood by the supposition that in these parts of the sea little or no life existed. But the same remark of the excessive rarity of life in the lower deposits is made in North America, in Norway, and in Bohemia, countries well searched for this very purpose, so that all our observations lead to the conviction that the lowest of all the strata are quite deficient of organic remains. The absence is general—it appears due to a general cause. Is it not probable that during these very early periods the ocean and its sediments were nearly devoid of plants and animals, and in the earliest time of all, which is represented by sediments, quite deprived of such?" These words were written ten years ago, and about the same time were published in America those anticipations of the probability of life in the Laurentian already referred to, and Lyell was protesting against the name Primordial, on the ground that it implied that we had reached the beginning of life, when this was not proved. Yet there were elements of truth in both views. It is true now, as then, that the Primordial seems to be a morning hour of life, having, as we shall see in our next paper, unmistakable signs about it of that approach to the beginning to which Phillips refers. It is also true that it is not so early a morning hour as one who has not risen with the dawn might suppose, since with its apparently small beginnings of life it is almost as far removed from the Eozoon reefs of the early Laurentian on the one hand, as it is from the modern period on the other. The dawn of life seems to have been a very slow and protracted process, and it may have required as long a time between the first appearance of Eozoon and the first of those primordial Trilobites which the next period will introduce to our notice, as between these and the advent of Adam. Perhaps no lesson is more instructive than this as to the length of the working days of the Almighty.
Another lesson lies ready for us in these same facts. Theoretically, plants should have preceded animals; and this also is the assertion of the first chapter of Genesis; but the oldest fossil certainly known to us is an animal. What if there were still earlier plants, whose remains are still to be discovered? For my own part, I can see no reason to despair of the discovery of an Eophytic period preceding the Eozoic; perhaps preceding it through ages of duration to us almost immeasurable, though still within the possible time of the existence of the crust of the earth. It is even possible that in a warm and humid condition of the atmosphere, before it had been caused “to rain upon the earth” and when dense “mists ascended from the earth and watered the whole surface of the ground,”[E] vegetation may have attained to a profusion and grandeur unequalled in the periods whose flora is known to us.
[E] Genesis ii. 5. For a description of this Eophytic period of Genesis, see the Author’s “Archaia,” pp. 160 et seq.
But while Eozoon thus preaches of progress and of development, it has a tale to tell of unity and sameness Just as Eozoon lived in the Laurentian sea, and was preserved for us by the infiltration of its canals with siliceous mineral matters, so its successors and representatives have gone on through all the ages accumulating limestone in the sea bottom. To-day they are as active as they were then, and are being fossilised in the same way. The English chalk and the chalky modern mud of the Atlantic sea-bed, are precisely similar in origin to the Eozoic limestones. There is also a strange parallelism in the fact that in the modern seas Foraminifera can live under conditions of deprivation of light and vital air, and of enormous pressure, under which few organisms of greater complexity could exist, and that in like manner Eozoon could live in seas which were perhaps as yet unfit for most other forms of life.
It has been attempted to press the Eozoic Foraminifers into the service of those theories of evolution which would deduce the animals of one geological period by descent with modification from those of another; but it must be confessed that Eozoon proves somewhat intractable in this connection. In the first place, the creature is the grandest of his class, both in form and structure; and if, on the hypothesis of derivation, it has required the whole lapse of geological time to disintegrate Eozoon into Orbulina, Globigerina, and other comparatively simple Foraminifers of the modern seas, it may have taken as long, probably much longer, to develop Eozoon from such simple forms in antecedent periods. Time fails for such a process. Again, the deep sea has been the abode of Foraminifers from the first. In this deep sea they have continued to live without improvement, and with little material change. How little likely is it that in less congenial abodes they could have improved into higher grades of being; especially since we know that the result in actual fact of any such struggle for existence is merely the production of depauperated Foraminifers? Further, there is no link of connection known to us between Eozoon and any of the animals of the succeeding Primordial, which are nearly all essentially new types, vastly more different from Eozoon than it is from many modern creatures. Any such connection is altogether imaginary and unsupported by proof. The laws of creation actually illustrated by this primeval animal are only these: First, that there has been a progress in creation from few, low, and generalised types of life to more numerous, higher, and more specialised types; and secondly, that every type, low or high, was introduced at first in its best and highest form, and was, as a type, subject to degeneracy, and to partial or total replacement by higher types subsequently introduced. I do not mean that we could learn all this from Eozoon alone; but that, rightly considered, it illustrates these laws, which we gather from the subsequent progress of the creative work. As to the mystery of the origin of living beings from dead matter, or any changes which they may have undergone after their creation, it is absolutely silent.