LETTER XX. NEW FORMATION OR ADJUSTMENT OF THE SURFACE, AFTER MY DEAR SYDNEY, XX. THAT the present surface of the earth on which we LETTER are living, was not, in all its regions, that primeval surface on which the first plants vegetated, the organic remains in several of the subterraneous rocks satisfactorily evince. The exterior masses of our globe, to the lowest depth that we have been able to explore, appear to consist of a succession of rocks, which have been traced and named, and of which you had a summary notice in the 7th and 18th of my former Letters, with a brief intimation of the vegetable and animal fossils which had been found among them. It would be too great a digression from the main and chosen subject of the present correspondence to enter into a review of the geological construction of our earth, altho it is an important compartment of its sacred history. But my other topics, and the limits which I have fixed for these pages, compel me to abstain from it, and only to desire you to bear in mind that the rocks and strata which we have attained to know, are distinguishable by a natural separation into two great divisions. Those which, containing no organic remains, give thereby evidence, that they were formed and laid down before plants and animals were created; and those which, XX. LETTER containing in several of their series and localities, fossil remains of organic life, must have been made and deposited at a subsequent period. The first are called the primordial or primary rocks, of which the chief members are granite, gneiss and mica slate; to which some minor and subordinate ones are in several places attached. These primordial rocks constitute the greatest bulk of our surface masses. The Granite formation appearing every where, and often uncovered by others, presents to us many indications that it is the foundation rock, on which all the others have been placed; and that it encompasses the whole circuit of the globe. Not so universal as this, but the next to it in extent and lying upon it, are the Gneiss rocks, which, in several countries predominate on the visible surface; and still less general, yet more so than any other, the Mica slate formation appears resting upon the gneiss, where that has preceded it, or on the granite, where no gneiss has been deposited. Upon these have been placed those which have been called transition, and intermediate, in their lower masses; and secondary in the upper ones; but to all of which we may apply the term Secondary, to distinguish them from a later series, which have been termed tertiary and diluvial. They comprise principally the slate formations, the grauwacke, and old and new red sandstones; the mountain and magnesian limestones; the oolites and lias, up to the great chalk beds, with some others less remarkable. On these, the tertiary and diluvial strata have been deposited, which are more immediately connected with the Deluge, as it is in some of these, always nearest the present surface, that the fossil XX. remains of quadrupeds and land animals have been LETTER found; which may be presumed to have been those who perished in that overwhelming catastrophe, which we have been recently considering. These recollections will be sufficient for my present subject, which is to lead your attention to the fact, that one great operation, and intended result, of the Deluge was, to lay a new surface on many parts of the antediluvian one, and to form that peculiar configuration and kind of habitable ground, which the human race, and our accompanying plants and animals, have ever since been occupying and subsisting on. In forming the new surface of the earth, it was peculiarly important to the future subsistence of the renewed human race, that the convulsions and agitations of the Deluge should be so directed, as that such earthy masses should be on the uppermost superficies, and in such a fragmentary and comminuted state, as would afterwards suit and produce that vegetation, those herbs, shrubs, roots and trees, from which our subsistence, conveniences and comforts were afterwards to arise. This event never could be a matter of course, because any rock, any sort of ground will not do. The sterile granite, the sandy desert, the flinty rock, the watery marsh, the hard limestone, the mere clay, the gravel, the unbroken lava, or the stony ground, will not furnish mankind with what they need for their food and welfare. The earth is suffered in many parts to exhibit all these appearances, in some portions, as if to show us, that undirected sequences of things, and what is called chance-formations, would not have provided for the human race those supplies, without which they could not have increased their numbers, or would have done so, but to LETTER drag on a miserable life, and to remain in a destitution like that of the Australian savages.' XX. Nor will every species of soil produce every kind of vegetation. Animals may need only grass; but it was intended that man should feed on corn, rice, and many other nutritious plants and roots, which will only grow or flourish on the soil which is adapted respectively to them. The trees also that were to exist for his benefit, and for that of the bird classes, and of the brute animals that live in the shade and forests, equally require suitable ground. It was therefore expedient that the plan should be settled, what the subsistence of man, after the Deluge, should consist of, and that the preceding surface should be so broken up or adapted, and its ruins so modified and intermingled, as that the new deposits from those commotions and changes should be such, as would every where nourish and yield to the human race those species and diversities of plants of all sorts, which their intended subsistence would require.3 1 Dr. Prout very appositely says, that it is the business of the geologist to point out the changes which our earth has evidently undergone, before it arrived at its present condition:-and to show that all these changes have not resulted from chance; but from the agency of an intelligent Being, operating with some ulterior purpose, and according to certain laws, to which He had chosen to restrict Himself.' Dr. Prout's Brid. Treat. P. 178-9. 2 Plants and trees, the roots of which are fibrous and hard, and capable of penetrating deep into the earth, will vegetate to advantage in almost all common soils that are moderately dry, and which do not contain a very great excess of vegetable matter. I found the soil taken from a field at Sheffield-place, in Sussex, remarkable for producing flourishing oaks, to consist of six parts of sand and one part of clay and finely divided matter-100 parts of the whole sort produced, silex 54, alumine 28, carbonate of lime 3, oxide of iron 5, water 3, decomposing vegetable matter 4.' Sir H. Davy's Analysis of Soils, p. 15. Dr. Prout adds, that the geologist should also demonstrate that to these very convulsions and changes we owe all that boundless variety of Let us see, from a few facts, what was necessary LETTER to be done and provided for in this respect. The antediluvian vegetation was very different from the present. This is the statement of the most eminent of the modern geologists: and the phenomena in the fossil matters of the earth have suggested, and justify the supposition. The difference was of two kinds; it was that of a tropical character, implying a temperature like that of the torrid zone, or equatorial regions, and displaying that largeness of size, which is only now found in regions where that degree of heat prevails; and it was also not of the leguminous species; not the corn plants, or the vegetables which now constitute the food of man, but it was of the reedy, fern-like, grassy, more aquatic and puny kinds, such as are adapted for the nutrition of brute animals; and obviously by its nature indicating that these were then living or predominating in those regions, where the embedded remains of this character appear.5 Mankind were then in some small parts of the globe, which have not yet been explored: and the rest of its surface was occupied by seas, lakes, vegetation, and the various orders of the animated creation, among whom the human race had not spread. This being the state of the antediluvian superficies of sea and land, of mountain and plain, of hill and valley; all that See the first vol. of this History, p. 236 9. XX. |