This concludes the general argument for organic creation by law, as preferable to that which, equally on hypothetic grounds, presumes a special exertion of divine power for each detached portion of that series of phenomena. We are now to inquire what organic nature herself says with respect to her origin; that is to say, whether she declares most loudly for the special or the general exercise of divine power in the production of her many tribes.

At the very first it may be frankly admitted, that there is no proof which has been satisfactory to the philosophical world, either of the origination of life from inorganic matter, or of the commencement of a new species, having ever once taken place since man first breathed on earth. It is not indeed strictly disproved that life is occasionally originated at the present time otherwise than by parentage; but neither has it been proved to the satisfaction of men of science that any such phenomenon ever did take place. There is here an appearance of strong presumption against the hypothesis of organic creation by law, and yet why should it be so considered? The great work of the peopling of this globe with living species is mainly a fact accomplished: the highest known species came as a crowning effect thousands of years ago. The work being thus, to all appearance, finished, we are not necessarily to expect that the origination of life and of species should be conspicuously exemplified in the present day.

The next volume of the rock series refers to an era distinguished by an event of no less importance than the abundant appearance of land animals. The New Red Sandstone System is subdivided into groups, some of which are wanting in some places. The lowest beds are those alluded to in the preceding chapter as presenting indications of disturbance. Next occur the strata of the Magnesian Limestone, denoting from their composition a recurrence of circumstances favourable to animal life. Beds usually called the Upper New Red Sandstone, followed in Germany by the Muschelkalk, or Shell Limestone, are next in the series; they are crowned by a group of Variegated Marls. This section of rocks forms, in whole, a sort of transitionary series, from the Carboniferous to the Oolitic; and, though peculiar in mineral constitution, might, as far as fossils are concerned, be very properly divided between the preceding and succeeding formations.

The plants of this era are few and unobtrusive. Equiseta, calamites, ferns, Voltzia, and a few of the other families, found so abundantly in the carboniferous series, here present themselves, but in diminished size and quantity.

The types of animal being which existed before—zoophytes, conchifers, mollusks, Crustacea, and fishes—continue to appear in the New Red Sandstone Rocks, being most numerous in the limestone beds, but particularly in the German sub-group of the Muschelkalk. All of these great classes are aquatic.

The Secondary Rocks, in which our further researches are to be prosecuted, consist of a great and varied series, resting, generally unconformably, against flanks of the upturned primary rocks, sometimes themselves considerably inclined, at others, forming extensive basin-like beds, nearly horizontal; in many places much broken up and shifted by disturbances from below. They have all been formed out of the materials of the older rocks, by virtue of the wearing power of air and water, which is still every day carrying down vast quantities of the elevated matter of the globe into the sea. But the separate strata are each much more distinct in the matter of its composition than might be expected. Some are siliceous or arenaceous, (sandstones,) composed mainly of fine grains from the quartz rocks — the most abundant of the primary strata. Others are argillaceous—clays, shales, &c, chiefly derived, probably, from the slate beds of the primary series. Others are calcareous, derived partly from the limestones, and partly eliminated from the waters of the ocean by organic life. As a general feature, they are softer and less crystalline than the primary rocks, as if they had endured less of both heat and pressure than the senior formation. There are beds (coal) formed solely of vegetable matter, and some others in which the conspicuous ingredient is a carbonate of iron, (the black band.) The secondary rocks are quite as communicative with regard to their portion of the earth's history as the primitive were.

Plaints and animals are classed into families, orders, classes, and sub-kingdoms, according as they agree in a smaller or greater number of characters, and take rank in compositeness or complexity of organization. The first difficulty of naturalists is to attain to a natural mode of classification, for there ever is a tendency to proceed upon certain formal, artificial ideas of our own, as presuming that the Divine Author of nature has acted upon some plan involving merely human ideas of regularity. Other difficulties arise when we inquire by what properties various organisms should be classed, many of these being identical or parallel in plants or animals, which in other respects are very different. It cannot be said that, in either kingdom, a satisfactorily natural system has been attained, nor, I venture to say, will any such system ever be formed, until there shall be a general consent to take a natural origin of organisms as partly our guide.

It is in the meantime seen with sufficient clearness, that the families of the vegetable and animal kingdoms can be arranged in grades from the highest forms in both instances to certain humble and simple types, amongst which it is hardly possible to discern any difference. In other words, both kingdoms start from certain humble and almost common forms, and advance to types of high organization in their respective departments.

Although the earth has not been actually penetrated to a greater depth than three thousand feet, the nature of its material can, in many instances, be inferred for the depth of many miles by other means of observation. We see a mountain composed of a particular substance, with strata, or beds of other rock, lying against its sloped sides; we, of course, infer that the substance of the mountain dips away under the strata which we see lying against it. Suppose that we walk away from the mountain across the turned up edges of the stratified rocks, and that for many miles we continue to pass over other stratified rocks, all disposed in the same way, till we at length come to a place where we begin to cross the opposite edges of the same beds. We then pass over these rocks, all in reverse order, till we come to another extensive mountain composed of similar material to the first, and shelving away under the strata in the same way. We should then infer that the stratified rocks occupied a basin formed by the material of these two mountains, and by calculating the thickness right through these strata, could say to what depth the rock of the mountain extended below. By such means, the kind of rock existing many miles below the surface can often be inferred with considerable confidence.

The record of this period consists of a series of strata, in which chalk beds make a conspicuous appearance, and which is therefore called the cretaceous system or formation. In England, a long stripe, extending from Yorkshire to Kent, presents the cretaceous beds upon the surface, generally lying conformably upon the oolite, and in many instances rising into bold escarpments towards the west. The celebrated cliffs of Dover are of this formation. It extends into Northern France, and thence north-westward into Germany, whence it is traced into Scandinavia and Russia. The same system exists in North America, and probably in other parts of the earth not yet geologically investigated. Being a marine deposit, it establishes that seas existed at the time of its formation on the tracts occupied by it, while some of its organic remains prove that, in the neighbourhood of those seas, there were tracts of dry land.

The cretaceous formation in England presents beds chiefly sandy in the lowest part, chiefly clayey in the middle, and chiefly of chalk in the upper part, the chalk beds being never absent, which some of the lower are in several places. In the vale of the Mississippi, again, the true chalk is wholly, or all but wholly absent. In the south of England, the lower beds are (reckoning from the lowest upwards), 1. Shankland or greensand, “a triple alternation of sands and sandstones with clay;” 2. Galt, “a stiff blue or black clay, abounding in shells, which frequently possess a pearly lustre;” 3. Hard chalk; 4. Chalk with flints; these two last being generally white, but in some districts red, and in others yellow.

We have now completed our survey of the series of stratified rocks, and traced in their fossils the progress of organic creation down to a time which seems not long antecedent to the appearance of man. There are, nevertheless, memorials of still another era or space of time which it is all but certain did also precede that event.

The first that calls for notice is the phenomenon to which geologists have applied the term denudation. Great hitches and slips are detected in superficial strata,—such as, if left in their original state, must have caused considerable inequalities on the face of the country; yet all is found as smooth—the joinings are all as much reduced to a common level—as if some gigantic artificial force had been used for the purpose. Again, a great valley has been scooped out in the midst of sedimentary strata, leaving the edges of these facing each other from the opposite sides, with perhaps here and there an isolated mass starting up to the height of the two sides, being composed of matter which has resisted the agency by which the adjoining matter was removed. Here, it is thought, we see incontestable traces of the operation of moving water.