The course of creation

by John Anderson

III. Universal, and shall we add, synchronous as a formation, there is a very interesting question connected with this subject, namely, is coal now forming? The general opinion among geologists leans to the affirmative side of the question, and that here, as in all the other cosmical arrangements going forward on the earth’s surface, time is the grand requisite. The necessary agencies are all at work, the other conditions are all admitted, and in the course of some future untold ages a new bituminous product will arise, similar in all respects to the old. The subject and the conclusions arrived at are not, however, free of many and great difficulties, to some of which we shall merely advert.

Reverting to all the circumstances connected with the geographical distribution of the coal metals, we are inclined to think that the era which produced them was not only peculiar in the wide geographical distribution of its families of plants, but equally, if not more so, in its limitation of all those physical conditions which were necessary for their conversion into coal. The basins, it will be observed, in which the vegetable matter was deposited, were, as compared with the existing ocean, small and shallow; for most of the plants and trees grew within their area or their immediate neighborhood, and are still found in their erect position, uninjured by roughing or transport in their smallest veinlets and even minute fructifications.

Then it is highly probable, that the great continents were not yet formed, but that a series of islands, barrier reefs, and inland seas, prevailed generally over the earth’s surface, being still chiefly oceanic. Consequently no great rivers could, in such circumstances, be in existence, rolling down like the Ganges, Nile, and Mississippi more stony detritus and mud than arborescent matter, and all to be mixed and confounded in one indiscriminate mass. Atmospheric influences, too, must have been widely different from what they now are; for all the cast-off apparel of a summer’s luxuriance is, we see year after year, speedily dissipated by the droughts, or absorbed back as humus into the earth, and when spring returns the ground is parched and bare. A difference of temperature must also be taken into the list of modifying causes; for the plants, during the coal era, are nearly of a class—a few great types with little variety of structure—one and the same in every region—and approaching the characters, most of them, of the existing tropical flora. The climate, according to Mr. Bunbury, was characterized by excessive moisture, by a mild and steady temperature, and the entire absence of frost; and it has been established by Mr. Darwin’s interesting observations on Chiloe and other islands of the southern temperate zone, that extreme heat is not necessary to the existence of a very luxuriant and quasi-tropical vegetation. Mr. Austen, on the other hand, thinks that the temperature of Great Britain has not much changed since the coal period, because few of the fossil-ferns, found in the coal-measures, present any fructification, while those in more southern latitudes possess it; and, by experiments made by himself, it appears that the existing ferns of tropical climates would not fructify at a low temperature. Still, the great general fact remains unquestioned, that tree-ferns during the carboniferous age grew gigantically and in vast forests, where they do not grow at present over all the zones of the earth; and where now growing, in three out of the four zones, that the whole family are reduced to the size of small herbaceous plants.

Now, is it not a legitimate inference from all this, that, out of so many concurring circumstances, not one of which is similar in all respects now, a determinate effect was intended to be produced, and which cannot, in the altered condition of things, be produced again? The argument is cumulative, and bears the strongest presumptive evidence on its side. The carboniferous series cannot be repeated—not for want of vegetable or animal matter, for there is a hundred times more of both at present on the surface of the earth than perhaps ever existed in any former period—but because there are so many new causes now in operation, so many changes in the relative position of sea and land, to modify its distribution and qualities, and to influence its place in the system generally, that the same conservative arrangements and chemical appliances cannot occur, nor any similar bituminous compound as a geological formation issue from Nature’s laboratory.

Leonard Horner, in enumerating the difficulties connected with the formation of the coal deposit upon the theory of the whole of the matter, vegetable and earthy, being spread over the sea-bottom, says—“That the terrestrial vegetable matter, from which coal has been formed, has in very many instances been deposited in the sea, is unquestionable, from their alternations with limestones containing marine remains.” Such deposits and alternations in an estuary at the mouth of a great river are conceivable; but whether such enormous beds of limestone, with the corals and molluscs which they contain, could be formed in an estuary, may admit of doubt. But it is not so easy to conceive the very distinct separation of the coal and the stony matter, if formed of drifted materials brought into the bay by a river. It has been said that the vegetable matter is brought down at intervals, in freshets, in masses united together, like the rafts in the Mississippi. But there could not be masses of matted vegetable matter of uniform thickness, 14,000 square miles in extent, like the Brownsville bed on the Monongahela and Ohio (the Pittsburgh seam): and freshets bring down gravel, and sand, and mud, as well as plants and trees. They must occur several times a year in every river; but many years must have elapsed during the gradual deposit of the sandstones and shales that separate the seams of coal. Humboldt tells us (“Cosmos,” p. 295),—That in the forest lands of the temperate zone, the carbon contained in the trees on a given surface would not, on an average of a hundred years, form a layer over that surface more than seven lines in thickness. If this be a well-ascertained fact, what an enormous accumulation of vegetable matter must be required to form a coal-seam of even moderate dimensions! It is extremely improbable that the vegetable matter brought down by rivers could fall to the bottom of the sea in clear unmixed layers; it would form a confused mass with stones, sand, and mud. Again, how difficult to conceive, how extremely improbable in such circumstances, is the preservation of delicate plants, spread out with the most perfect arrangement of their parts, uninjured by the rude action of rapid streams and currents, carrying gravel and sand, and branches and trunks of trees?”

Nor, according to Mr. Horner, are the objections to the lacustrine theory, requiring so many oscillations of land and water, of less magnitude. “In the theory,” he says, “which accounts for the formation of beds of coal, by supposing that they are the remains of trees and other plants that grew on the spot where the coal now exists, that the land was submerged to admit of the covering of sandstones or shale being deposited, and again elevated, so that the sandstone or shale might become the subsoil of a new growth, to be again submerged, and this process repeated as often as there are seams of coal in the series—these are demands on our assent of a most startling kind. The materials of each of these seams, however thin (and there are some not an inch thick, lying upon and covered by great depths of sandstones and shales), must, according to this theory, have grown on land, and the covering of each must have been deposited under water.—There must thus have been an equal number of successive upward and downward movements, and these so gentle, such soft heavings, as not to break the continuity, or disturb the parallelism of horizontal lines spread over hundreds of square miles; and the movements must, moreover, have been so nicely adjusted, that they should always be downward when a layer of vegetable matter was to be covered up; and, in the upward movements, the motion must always have ceased so soon as the last layers of sand or shale had reached the surface, to be immediately covered by the fresh vegetable growth; for otherwise we should have found evidence, in the series of successive deposits, of some being furrowed, broken up, or covered with pebbles or other detrital matter of land, long exposed to the waves breaking on a shore, and to meteoric agencies. These conditions, which seem to be inseparable from the theory in question, it would be difficult to find anything analogous to in any other case of changes in the relative level of sea and land with which we are acquainted.”

While these statements show that we are still but imperfectly acquainted with all the conditions and circumstances under which coal was formed, two deductions may be made from them, not only as against the rival theories themselves, of Murchison and Lyell, but still more strongly against the application of either theory to existing causes in the formation of the true bituminous product. In the first place, the vegetable matter brought down by the rivers, and spread over the bottom of the sea, does not amount to an infinitesimal fraction of what constitutes the enormous compound of the carboniferous age; and a different effect, according to the laws of nature of which we have experience, will necessarily result from the causes now in operation. Secondly, whatever, as a question of fact, it may have been with our coal-basins in the times gone by, certain it is that NOW there are no such oscillatory movements, causing the required changes in the relative level of sea and land, in those quarters of the globe the most densely covered with forests and jungle, and out of which the new coal-measures are expected to rise. The thin accumulations of woody residuum, observed by Sir Charles Lyell, in the sections exposed along the banks of rivers, railways, and other passages through American prairies and forests, are all unfavorably circumstanced—firm as the everlasting hills on their rocky foundations.

We may be reminded of the numberless ages required for the production of coal, that man’s experience is but of yesterday, and himself an ephemeral of a moment as compared with the revolutions of time recorded on the fabric of the globe. This record, we have reason to think, should be vastly abridged. But grant it, for the sake of argument, in all its indefinite dimensions, and still the answer is, that a moment in a question of this kind is just as instructive as the lapse of a million of years. Time, while it witnesses change, does not create or of itself produce anything. It is rather a passive than an active agent. Time marks on its horoscope the effects of existing causes, but the causes themselves it neither fashions or eliminates. Geologists enter into minute calculations as to the annual decay of vegetables, and the transporting powers of water, the waste of forests and the uptearing of hurricanes. Grant them all to be correct, and the data in these respects to be unchallengeably sound, we again beg them to consider that the Mississippi bears on its bosom the earthy spoils of half a continent—that the Ganges mixes in its fabled flood the varied wreck of all the Himalaya,—and when all are duly borne onward by these and the mighty rivers elsewhere on the globe, that the arrangement of the mingled composite has yet to be effected—the clays, sands, coals, conglomerates, all in their serial superposition—the separation of the clean from the unclean—and where is the agency thus to dispose and to proportion? The deep says, it is not in me. The rivers show it is not in them. Are there any cosmical affinities in the things themselves to cause each to each, kind to kind, to take their respective places?

When we are told, that we know not what is going on in the depths of ocean, and other hollow places of the earth, our answer is two-fold. For first we reply, there were depths and hollows, lakes, estuaries, and seas, during all the intermediate succeeding epochs to the present age, and no true coal was produced: accumulation after accumulation of detrital alluvia followed, lapidified, and was distributed over extensive areas, and common to every region of the globe; but the real bituminous treasure has not been uniformly an accompaniment. A second answer is, that when and where vegetable matter, in any quantity, did accumulate, the result of the process was not coal. The lignites of the tertiary deposits, and many of the oolites, have been subjected to the first and second stages only in those changes which plants undergo in their transition into the bituminous combustible. Nature in these instances, if we may use the expression, has made the effort, but the same results have not followed; the process is incomplete, and the product is only in patches. If we are reminded of the great oolitic deposit of Richmond, in Virginia, re-examined and pronounced to be so by Sir C. Lyell, some may still say non-content, that the problem is not yet solved as to the true position of the coal there. Many anomalies in geognostic arrangements occur in that vast continent: many of the intermediate series up to the chalk are absent altogether, and the sandstones, discriminating the new from the old red, are not fully determined. Lignite, in considerable quantity, exists among the tertiary deposits of the Alps, and has recently been found in the north-west provinces of India, in the vicinity of Kalibag; but all partaking of the usual qualities—wood, only partially altered by inhumation, and imperfectly adapted for domestic purposes.

One overwhelming consideration with us, in the discussion of this question, is the position which man occupies, and the part he now plays on the theater of creation. The beasts and quadrupeds of the earth do not appear to have been formed so early as the carboniferous epoch. Had they existed at the period it is impossible to say what effects would have resulted from their graminivorous propensities in modifying the amount of the vegetable exuviæ. But man has appeared, modifying, changing, controlling everything—the earth and all its stores under his dominion—and all submissive to his will. He has little influence, indeed, over the more solid departments or structure of the globe—the form of its continents—the direction of its oceanic currents—the rise of islands and depression of land—the movements of the earthquake, and fiery torrents of the volcano; but over all its living products, especially its vegetable and terrestrial animal tribes, his influence is immense—increasingly incalculable. And, the geologist says, had this new denizen left the earth to itself, and nature to her own arrangements—were there no tilling, draining, and reaping—were the jungle and the wilderness to be still uninvaded—the marsh and the lagoon to welter in their dreary desolation—a vast coal deposit would be preparing in all the great lakes and seas of the globe. These postulates and conditions, however, can no longer be granted. Every day and every season they are all curtailed and limited in their influences. Man cuts down the forest, and applies it in its green, woody state to his own use.—The waste is reclaimed. The desert he makes his habitation; a place of beauty and civilization. The moral triumphs over the material, the spiritual over the earthy, and his charter-right is to subdue all things to himself. Thus the geologist cannot, if he would, forget or overlook the remarkable human epoch in which his own lot has been cast. As regards the future, there is a new element to which a due place must be assigned in his speculations; and all the great revolutions, and after-phases of our globe, he must henceforth read and interpret in the revealed destiny of his own race.