upon our own bodies; when, of course, the internal heat rises through each coat in succession, and the third (supposing there is a fourth above it) becomes as warm as perhaps the first originally was. In speaking of sedimentary rocks, we may be said to be anticipating. It is necessary, first, to shew how such rocks were formed, or how stratification commenced. Geology tells us as plainly as possible, that the original crystalline mass was not a perfectly smooth ball, with air and water playing round it. There were vast irregularities in the surface,—irregularities trifling, perhaps, compared with the whole bulk of the globe, but assuredly vast in comparison with any which now exist upon it. These irregularities might be occasioned by inequalities in the cooling of the substance, or by accidental and local sluggishness of the materials, or by local effects of the concentrated internal heat. From whatever cause they arose, there they were—enormous granitic mountains, interspersed with seas which sunk to a depth equally profound, and by which, perhaps, the mountains were wholly or partially covered. Now, it is a fact of which the very first principles of geology assure us, that the solids of the globe cannot for a moment be exposed to water, or to the atmosphere, without becoming liable to change. They instantly begin to wear down. This operation, we may be assured, proceeded with as much certainty in the earliest ages of our earth’s history, as it does now, but upon a much more magnificent scale. There is the clearest evidence that the seas of those days were not in some instances less than a hundred miles in depth, however much more. The sub-aqueous mountains must necessarily have been of at least equal magnitude. The system of disintegration consequent upon such conditions would be enormous. The matters worn off, being carried into the neighbouring depths, and there deposited, became the components of the earliest stratified rocks, the first series of which is the _Gneiss and Mica Slate System_, or series, examples of which are exposed to view in the Highlands of Scotland and in the West of England. The vast thickness of these beds, in some instances, is what attests the profoundness of the primeval oceans in which they were formed; the Pensylvanian grawacke, a member of the next highest series, is not less than a hundred miles in direct thickness. We have also evidence that the earliest strata were formed in the presence of a stronger degree of heat than what operated in subsequent stages of the world, for the laminæ of the gneiss and of the mica and chlorite schists are contorted in a way which could only be the result of a very high temperature. It appears as if the seas in which these deposits were formed, had been in the troubled state of a caldron of water nearly at boiling heat. Such a condition would probably add not a little to the disintegrating power of the ocean.