The course of creation

by John Anderson

The introduction of new and higher races upon the earth has thus been accounted for. “Through such a medium as the air,” says the authority quoted above, “approaching in a corresponding degree to the physical properties of water, a cold-blooded animal might even rise above the surface, and wing its heavy flight, since this would demand less energetic muscular actions than are now requisite for such a kind of locomotion: and thus we may conceive why the atmosphere of our planet, during the earlier oolite periods, may have been traversed by creatures of no higher organization than saurians. If we may presume to conjecture that atmospheric pressure has been diminished, by a change in the composition, as well as by a diminution of the general mass of the air, the beautiful adaptation of the structure of birds to a medium thus rendered both lighter and more invigorating, by the abstraction of carbon and an increase of oxygen, must be appreciable by every physiologist. And it is not without interest to observe, that the period when such change would be thus indicated by the first appearance of birds in the Wealden strata, is likewise characterized by the prevalence of those dinosaurian reptiles, which in structure most nearly approach mammalia, and which in all probability, from their correspondence with crocodiles in the anatomy of the thorax, enjoyed a circulation as complete as that of the crocodile when breathing freely on dry land.”

Again, it is conjectured—“The first indications of the warm-blooded classes would appear, if introduced into the reptilian era, under the form of such small insectivorous mammals as are known at the present day to have a lower amount of respiration than the rest of the class; and the earliest discovered remains of mammalia,—as, for example, those in the Stonesfield oolite,—are actually the jaws of such species, with which are combined the characters of that order, Marsupialia, which is most nearly related to the oviparous vertebrata.”

It has been seen that igneous and aqueous agents have remodeled, from time to time, the physical geography of the globe. Can it admit of a doubt that changes in the physical structure of the earth’s surface will be accompanied with other changes in the organic productions of extensive areas? Species, it is well known, both of plants and animals, are limited to particular localities of variable, and often of no great, extent. If marine, an alteration in the sea bottom will prove fatal to many. If terrestrial, an increase of altitude, the conversion of dry land into marshes and lakes, or of lakes and marshes into meadow and arid loamy soil, will completely alter the flora and fauna of the district in question. Look into any estuary or rocky pool along the shore of the ocean, swarming with testacea, and crustacea; every bowlder incrusted with corallines; the rocks carpeted all over with fuci, waving with every ripple their long graceful branches, or smoothing and polishing their sides in the violent currents; creeping things, too, innumerable shy stealthy creatures, darting amid the shingle, or burrowing in the sands; and the finny tribes, of all forms, glancing and sparkling like living gems in the dark green thickets. This is one description only of tens of thousands of such phenomena around the islands of Great Britain. An elevation of a few feet, and what myriads of animals, whose only habitat are these ocean caves, would perish, and their races be forever blotted from the things that were! These shores have witnessed many such upheavals. Not a plain, hill, or rock, in the whole continent of Europe, but once formed the bed of the sea. Even now, what a vast influence does mineralogical structure alone exercise over the economy of life, both as to the number of individuals and the character of species frequenting particular localities. Trees as well as plants have an adaptation to certain kinds of soil, and once firmly rooted, birds, insects, and creeping things, will also resort thither in quest of shelter or of food. Aquatic fowl, the waders and swimmers of our sea-shores, have their favorite haunt among the breakers or calm bays, whose submarine rocks furnish pasturage and shelter to molluscs, crustaceans, and fishes; while, again, over the marshy, the oozy, the sandy, the gravelly, or the rocky beach, other families, both terrestrial and marine, maintain their respective ascendency.

M. Agassiz is just now pursuing his favorite researches in exploring the lakes and rivers of America, where he has already detected many things new and old to enlighten the western savans in the boundless riches of their mighty dominions. He has succeeded in capturing, on Lake Superior, species of fishes hitherto unnamed. He has likewise been able to dredge up from the same deep waters, specimens of the garpike (Lepidosteus), whose representatives have been found in the oldest palæozoic deposits, and in the deposits of all succeeding times. Suppose these lakes to be suddenly drained of their waters—and which, according to the chronometrical details of Niagara, must one day come to pass—and many species of animals and plants would cease to exist, not merely by the violence of the action, but by the simple alteration of the aqueous character of the districts. Many animals, indeed, will be able to escape, and to betake themselves to other localities amidst slow or even rapid superficial changes. The camels and antelopes of the desert may sink under the sirocco and be buried in the sand; but, in other circumstances, they will be able to bear up and carry themselves to fertile lands, as the steady, irresistible march of the sand-flood invades their former pastures. The Sahara of Africa has been gradually extending and widening in its desolating sterility, until it now covers a region of about 582,000 square miles; how many, in consequence, of the vegetable and animal races, have thus been deprived of their appropriate nutriment, and become extinct? How many examples of similar devastations, but upon a far greater scale, does almost every one of the geological epochs furnish? The central region of France abounded with lakes, attracting to their arborescent banks the huge pachyderms of the tertiary age, when the Auvergne cones blazed out, pouring floods of lava over lake, marsh, and plain; and thus obliterating and silting up entire races, the great and the small, terrestrial and lacustrine, and now constituting the pictorial wonders of the age that produced, and the convulsions that destroyed them.

There is reason to believe that species in the ancient world were possessed of a wider geographical range than in after periods. But the causes of extirpation were also of wider operation. The old formations are all greater than the new, receding in extent as they descend in time. And if we are to regard alterations of climate, changes in the constituents of the atmosphere, subsidence of land and elevation of sea-bottom, intrusion of igneous rocks, the escape and circulation of noxious gaseous matter, as among the causes which have led to the extinction of the successive organic tribes in the several geological epochs, so do we find the effects approximating to a scale of corresponding magnitude. But the real terms and boundaries of all are in the hands of Him who made them. We see but a part, and know only in part, of the secondary means of destruction.

CHAPTER V.
TIME, AND THE GEOLOGICAL EPOCHS.

The speculations of geology respecting the arrangement and position of the mineral masses of the earth are matters of direct observation, falling immediately under the cognizance of the senses, and whose verifications are both numerous and conclusive. But a question thereupon arises which is not so easily dealt with, namely, as to the periods of time that have elapsed during the various successive epochs or formations described. Looking at the current operations of the laws of nature, and supposing their uniformity in past ages, a scale of increment is laid down for the several deposits of which the earth’s crust is composed. An approximation is made as to the number of years required for each, and the result is, that the geological estimate embraces an inconceivably lengthened and bewildering series. The calculation proceeds not by hundreds, or thousands, but by millions of the terms of our numerical notation: and, as the fossiliferous strata alone are reckoned at about seven or eight miles in thickness, the time that has elapsed since the first appearance of life upon the planet, has also been made a matter of measurement. Accuracy as to any precise definite amount, is not, indeed, pretended; but no estimate, it is said, made upon purely geological data, falls short of vast enormous periods, which will only bear to be compared with the cycles of astronomical phenomena, and not with the brief fleeting days of man’s existence.

What account, then, is to be made of this reckoning according to the popular opinions respecting the origin of the world? Will it be accepted by the Christian, who confides in the Mosaic chronology of the work of creation? What is that chronology? Can the geological and the sacred be compared or reconciled with one another?