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 laminae 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.

The earliest stratified rocks contain no matters which are not to be
found in the primitive granite. They are the same in material, but
only changed into new forms and combinations; hence they have been
called by Mr. Lyell, metamorphic rocks. But how comes it that some
of them are composed almost exclusively of one of the materials of