Outlines of Creation

by Elisha Noyce

Upon a close examination of the various strata which form the crust of the earth, it is found that each has its own peculiar character; some have resulted from the accumulation of matters deposited at the bottom of ancient seas, others in the beds of rivers or fresh-water lakes, or again others (as the coal formation) from the accumulation of vegetable matters; further, these strata do not only differ in structure and composition, but also in the remains of animals and plants found in them; for there is scarcely any kind of soil (above the primary rocks) in which abundant remains of these have not been found. It will now be proper to give a description of them in succession, beginning at the lowest or primary, granite.

FIG. 7.

This appears to be the result of the cooling and crystallisation of that molten mass which many circumstances (hereafter to be mentioned) point out as making up the great body of the earth. Granite differs, in various places, in colour and quality (the varieties are known as "sienite," "porphyry," "greenstone," &c.), but still retains its own distinctive characters; it is a hard, crystalline rock, consisting of "felspar," "mica," and "quartz," in separate crystals, but mechanically blended; its chemical composition as a whole is silica, alumina, and potassa, with small quantities of lime and oxide of iron. This granite is met with everywhere, if the outer crust of the earth be penetrated to a sufficient depth; it however frequently exists on the surface, having no strata below it, and in some places overlies other strata—this, and the fact that cracks and crevices of some of the lower strata are filled up with granite, which could only have taken place while it was in a liquid state, as in fig. 8, together with evidences of the effects of calcination, and other changes producible only by extreme heat, all around those parts and in the strata immediately overlaying the granite, point out that it was once in a state of fusion.

Above the granite formation, in many places, especially in Norway and Sweden, there is a stratum of rock called gneiss, which consists of the same ingredients as granite in a slightly altered form. Granite will often pass into gneiss gradually, and this again into those slaty formations which rest upon it and come next in the series. These consist of mica-slate, hornblend-slate, and chlorite-slate or schist, a name given to all those rocks of a slaty structure which have a cleavage or capability of being cleft into thin laminæ or slices (hence their applicability to the purposes of building, forming excellent roofing materials, &c.).

FIG. 8.

All these rocks have received the name of "primary," they have no appearance of being stratified or deposited in layers, which appearance seems to be in all cases the result of having at some time been suspended in water and thence deposited gradually as mud, sand, &c., time, pressure, and heat having afterwards altered their consistence. All these consist of the earths described as composing granite, but combined in different proportions. Above these rocks there is a formation of a totally different composition, namely crystalline limestone, commonly known as marble; this consists wholly of carbonate of lime or lime in union with carbonic acid, and its crystalline state appears to have been produced by long-continued heat and pressure. This limestone is by many ranked amongst the primary rocks, although it differs so entirely in its composition which exactly resembles a formation presently to be described (the chalk); however, if this be classed with the primary rocks, then it may be fairly said that all above have resulted from their disintegration and reunion in different forms, by the action of water and vital forces of different kinds. The state of the earth at the close of this the "primary period" may now be considered.

The early history of our globe forms one of the great problems of geology, but there is evidence enough upon which to form conclusions and show that the earth had undergone some great and varied changes embracing immense periods of time, and if the sciences of astronomy, chemistry, mathematics, &c., be brought in to assist the inquiry, some plain facts become evident. Astronomy shows us orbs circulating round the sun (the planets), strictly analogous to our earth, and furnishes us with their densities; these are found to be various, ranging from about six times the density of water to half its density. The planets appear to be at different stages of condensation, and it is not unreasonable to suppose that our earth was once of no greater density than the lightest of them. The inner ring of Saturn is probably in a liquid state, for it is transparent. The substance of which comets are composed is a vapour, so rare and thin that it cannot be compared in density to our atmosphere even, and yet these comets preserve their identity, circulating through immense realms of space with prodigious rapidity. Thus astronomy presents analogies in favour of the supposition that the earth was once gaseous, or at all events of much less density than at present; but mathematical inquiries go much further, and furnish almost proof that the earth was once (if not now) in a liquid state, for the exact form which a liquid ball would assume upon rotating at the rate which the earth does, is exactly that which the globe is found by measurement to possess.

Chemistry has ascertained that the heat of the earth is far greater than any tract of the heavens through which it passes; that this heat could not have been communicated by the sun's rays, for had it been so the surface would be hotter than the interior, the very reverse of which is found to be the fact, and the deeper we go down the higher the temperature is. Chemistry shows further that this heat can be completely accounted for by the condensation and solidification of the earth itself; for the condensation of all gases into liquids, and of liquids into solids, causes a very large portion of latent caloric to become sensible, for example, any quantity of a gas at 60 deg. suddenly reduced to a smaller bulk, would have a temperature higher than 60 deg. A little contrivance has long been in use for obtaining fire by this process, consisting of a cylinder and piston, the rod of which if struck down sets fire to a piece of German-tinder. It is probable that all fire, and every alteration of temperature, are due to this one cause alone.