The Foot-prints of the Creator

by Hugh Miller

This fact of degradation, strangely indicated in geologic history, with reference to all the greater divisions of the animal kingdom, has often appeared to me a surpassingly wonderful one. We can see but imperfectly, in those twilight depths to which all such subjects necessarily belong; and yet at times enough does appear to show us what a very superficial thing infidelity may be. The general advance in creation has been incalculably great. The lower divisions of the vertebrata preceded the higher;—the fish preceded the reptile, the reptile preceded the bird, the bird preceded the mammiferous quadruped, and the mammiferous quadruped preceded man. And yet, is there one of these great divisions in which, in at least some prominent feature, the present, through this mysterious element of degradation, is not inferior to the past? There was a time in which the ichthyic form constituted the highest example of life; but the seas during that period did not swarm with fish of the degraded type. There was, in like manner, a time when all the carnivora and all the herbivorous quadrupeds were represented by reptiles; but there are no such magnificent reptiles on the earth now as reigned over it then. There was an after time, when birds seem to have been the sole representatives of the warm-blooded animals; but we find, from the prints of their feet left in sandstone, that the tallest men might have

“Walked under their huge legs, and peeped about.”

Further, there was an age when the quadrupedal mammals were the magnates of creation; but it was an age in which the sagacious elephant, now extinct, save in the comparatively small Asiatic and African circles, and restricted to two species, was the inhabitant of every country of the Old World, from its southern extremity to the frozen shores of the northern ocean; and when vast herds of a closely allied and equally colossal genus occupied its place in the New. And now, in the times of the high-placed human dynasty,—of those formally delegated monarchs of creation, whose nature it is to look behind them upon the past, and before them, with mingled fear and hope, upon the future,—do we not as certainly see the elements of a state of ever-sinking degradation, which is to exist for ever, as of a state of ever-increasing perfectibility, to which there is to be no end? Nay, of a higher race, of which we know but little, this much we at least know, that they long since separated into two great classes,—that of the “elect angels,” and of “angels, that kept not their first estate.”

EVIDENCE OF THE SILURIAN MOLLUSCS—OF THE FOSSIL FLORA.
ANCIENT TREE.

After dwelling at such length on the earlier fishes, it may seem scarce necessary to advert to their lower contemporaries the mollusca,—that great division of the animal kingdom which Cuvier places second in the descending order, in his survey of the entire series, and first among the invertebrates; and which Oken regards as the division out of which the immediately preceding class of the vertebral animals have been developed. “The fish,” he says, “is to be viewed as a mussel, from between whose shells a monstrous abdomen has grown out.” There is, however, a peculiarity in the molluscan group of the Silurian system, to which I must be permitted briefly to refer, as, to employ the figure of Sterne, it presents “two handles” of an essentially different kind, and as in all such two-handled cases, the mere special pleader is sure to avail himself of only the handle which best suits his purpose for the time.

Cuvier’s first and highest class of the molluscs is formed of what are termed the Cephalopods,—a class of creatures possessed of great freedom of motion: they can walk, swim, and seize their prey; they have what even the lowest fishes such as the lancelet, want,—a brain enclosed in a cartilaginous cavity in the head, and perfectly formed organs of sight; they possess, too, what is found in no other mollusc,—organs of hearing; and in sagacity and activity they prove more than matches for the smaller fishes, many of which they overmaster and devour. With this highest class there contrasts an exceedingly low molluscous class at the bottom of the scale, or, at least, at what is now the bottom of the scale; for they constitute Cuvier’s fifth class; while his sixth and last, the Cirrhopodes, has been since withdrawn from the molluscs altogether, and placed in a different division of the animal kingdom. And this low class, the Brachiopods, are creatures that, living in bivalve shells, unfurnished with spring hinges to throw them open, and always fast anchored to the same spot, can but thrust forth, through the interstitial chinks of their prison-houses, spiral arms, covered with cilia, and winnow the water for a living. Now, it so happens that the molluscan group of the Silurian system is composed chiefly of these two extreme classes. It contains some of the other forms; but they are few in number, and give no character to the rocks in which they occur. There was nothing by which I was more impressed, in a visit to a Silurian region, than that in its ancient graveyards, as in those of the present day, though in a different sense, the high and the low should so invariably meet together. It is, however, not impossible that, in even the present state of things, a similar union of the extreme forms of the marine mollusca may be taking place in deep-sea deposits. Most of the intermediate forms provided with shells capable of preservation, such as the shelled Gasteropoda and the Conchifers, are either littoral, or restricted to comparatively small depths; whereas the Brachiopoda are deep-sea shells; and the Cephalopoda may be found voyaging far from land, in the upper strata of the sea above them. Even in the seas that surround our own island, the Brachiopodous molluscs—terebratula and crania—have been found, ever since deep-sea dredging became common, to be not very rare shells; and in the Mediterranean, where they are less rare still, fleets of Argonauts, the representatives of a highly organized family of the Cephalopods, to which it is now believed the Bellerophon of the Palæozoic rocks belonged, may be seen skimming along the surface, with sail and oar, high over the profound depths in which they lie. And, of course, when death comes, that comes to high and low, the remains of both Argonauts and Brachiopods must lie together at the bottom, in beds almost totally devoid of the intermediate forms.

Now, the author of the “Vestiges,” in maintaining his hypothesis, suspends it on the handle furnished him by the immense abundance of the Silurian Brachiopods. The Silurian period, he says, exhibits “a scanty and most defective development of life; so much so, that Mr. Lyell calls it, par excellence, the age of Brachiopods, with reference to the by no means exalted bivalve shell-fish which forms its predominant class. Such being the actual state of the case, I must persist in describing even the fauna of this age, which we now know was not the first, as, generally speaking, such a humble exhibition of the animal kingdom as we might expect, upon the development theory, to find at an early stage of the history of organization.” The reader will at once discern the fallacy here. The Silurian period was peculiarly an age of Brachiopods, for in no other period were Brachiopods so numerous, specifically or individually, or of such size or importance; whereas it was not so peculiarly an age of Cephalopods, for these we find introduced in still greater numbers during the Liasic and Oolitic periods. In 1848, when Professor Edward Forbes edited the Palæontological map of Britain and Ireland, which forms one of the very admirable series of “Johnstone’s Physical Atlas,” the Cephalopods of the Silurian rocks of England and Wales were estimated at forty-eight species, and the Brachiopods at one hundred and fifty; whereas at the same date there were two hundred and five Cephalopods of the Oolitic formations enumerated, and but fifty-four Brachiopods. It is the molluscs of the inferior, not those of the superior class, that constitute (with their contemporaries the Trilobites) the characteristic fossils of the Silurian rocks; and hence the propriety of the distinctive name suggested by Sir Charles Lyell. But in the development question, what we have specially to consider is, not the numbers of the low, but the standing of the high. A country may be distinctively a country of flocks and herds, or a country of the carnivorous mammalia, or, like New South Wales or the Galapagos, a country of marsupial animals or of reptiles. Its human inhabitants may be merely a few hunters or shepherds, too inconsiderable in numbers, and too much like their brethren elsewhere, to give it any peculiar standing as a home of men. But in estimating the highest point in the scale to which the animal kingdom has attained within its limits, it is of its few men, not of its many beasts, that we must take note. And the point to be specially decided regarding the organisms of the Silurian system, in this question, is, not the proportion in number which the lower forms bore to the higher, but the exact rank which the higher bore in the scale of existence. Did the system furnish but a single Cephalopod or a single fish, we would yet have as certainly to determine that the chain of being reached as high as the Cephalopod or the fish, as if the remains of these creatures constituted its most abundant fossils. The chain of animal life reached quite as high on the evening of the sixth day of creation, when the human family was restricted to a single pair, as it does now, when our statists reckon up by millions the inhabitants of the greater capitals of the world; and the special pleader who, in asserting the contrary, would insist on determining the point, not by the rank of the men of Eden, but by the number of minnows or sticklebacks that swarmed in its rivers, might be perhaps deemed ingenious in his expedients, but certainly not very judicious in the use of them. It is worthy of remark, however, that the Brachiopods of those Palæozoic periods in which the group occupied such large space in creation, consisted of greatly larger and more important animals than any which it contains in the present day. It has yielded to what geological history shows to be the common fate, and sunk into a state of degradation and decline.

The geological history of the vegetable, like that of the animal kingdom, has been pressed into the service of the development hypothesis; and certainly their respective courses, both in actual arrangement and in their relation to human knowledge, seem wonderfully alike. It is not much more than twenty years since it was held that no exogenous plant existed during the Carboniferous period. The frequent occurrence of Coniferæ in the Secondary deposits had been conclusively determined from numerous specimens; but, founding on what seemed a large amount of negative evidence, it was concluded that, previous to the Liasic age, nature had failed to achieve a tree, and that the rich vegetation of the Coal Measures had been exclusively composed of magnificent immaturities of the vegetable kingdom,—of gigantic ferns and club-mosses, that attained to the size of forest trees, and of thickets of the swamp-loving horsetail family of plants, that well nigh rivalled in height those forests of masts which darken the rivers of our great commercial cities. Such was the view promulgated by M. Adolphe Brongniart; and it may be well to remark that, so far as the evidence on which it was based was positive, the view was sound. It is a fact, that inferior orders of plants were developed in those ages in a style which, in their present state of degradation, they never exemplify: they took their place, not, as now, among the pigmies and abortions of creation, but among its tallest and goodliest productions. It is, however, not a fact that they were the highest vegetable forms of their time. True exogenous trees also existed in great numbers and of vast size. In various localities in the coal fields of both England and Scotland,—such as Lennel Braes and Allan Bank in Berwickshire, High-Heworth, Fellon, Gateshead, and Wideopen near Newcastle-upon-Tyne, and in quarries to the west of the city of Durham,—the most abundant fossils of the system are its true woods. In the quarry of Craigleith, near Edinburgh, three huge trunks have been laid open during the last twenty years, within the space of about a hundred and fifty yards, and two equally massy trunks, within half that space, in the neighboring quarry of Granton, all low in the Coal Measures. They lie diagonally athwart the strata,—at an angle of about thirty,—with the nether and weightier portion of their boles below, like snags in the Mississippi; and we infer, from their general direction, that the stream to which they reclined must have flowed from nearly north-east to south-west. The current was probably that of a noble river, which reflected on its broad bosom the shadow of many a stately tree. With the exception of one of the Granton specimens, which still retains its strong-kneed roots, they are all mere portions of trees, rounded at both ends as if by attrition or decay; and yet one of these portions measures about six feet in diameter by sixty-one feet in length; another four feet in diameter by seventy feet in length; and the others, of various thickness, but all bulky enough to equal the masts of large vessels, range in length from thirty-six to forty-seven feet. It seems strange to one who derives his supply of domestic fuel from the Dalkeith and Falkirk coal-fields, that the Carboniferous flora could ever have been described as devoid of trees. I can scarce take up a piece of coal from beside my study fire, without detecting in it fragments of carbonized wood, which almost always exhibit the characteristic longitudinal fibres, and not unfrequently the medullary rays. Even the trap-rocks of the district enclose, in some instances, their masses of lignite, which present in their transverse sections, when cut by the lapidary, the net-like reticulations of the coniferæ. The fossil botanist, who devoted himself chiefly to the study of microscopic structure, would have to decide, from the facts of the case, not that trees were absent during the Carboniferous period, but that, in consequence of their having been present in amazing numbers, their remains had entered more palpably and extensively into the composition of coal than those of any other vegetable.[32] So far as is yet known, they all belonged to the two great divisions of the coniferous family, araucarians and pines. The huge trees of Craigleith and Granton were of the former tribe, and approximate more nearly to Altingia excelsa, the Norfolk-Island pine,—a noble araucarian, that rears its proud head from a hundred and sixty to two hundred feet over the soil, and exhibits a green and luxuriant breadth of foliage rare among the Coniferæ,—than any other living tree.