Beneath the whole series of stratified rocks
that appear on the surface of the globe (see
section PI. 1), there probably exists a foundation
of unstratified crystalline rocks; bearing
an irregular surface, from the detritus of which
the materials of stratified rocks have m great
measure been derived,* amounting, as we have
stated, to a thickness of many miles. This is
indeed but a small depth, in comparison with
the diameter of the globe; but small as it is, it
affords certain evidence of a long series ol
changes and revolutions; affecting not only the
mineral condition of the nascent surface of the
earth, but attended also by important alterations
in animal and vegetable life.
The detritus of the first dry lands, being
drifted into the sea, and there spread out into
extensive beds of mud and sand and gravel,
would for ever have remained beneath the surface
of the water, had not other forces been
subsequently employed to raise them into dry
land : these forces appear to have been the same
expansive powers of heat and vapour which
having caused the elevation of the first raised
portions of the fundamental crystalline rocks,
* Either directly, by the accumulation of the ingredients o
disintegrated granitic rocks; or indirectly, by the repeated destruction
of different classes of stratified rocks, the materials o
which had. by prior operations, been derived from unstratified
formations.
continued their energies through all succeeding
geological epochs, and still exert them in producing
the phenomena of active volcanoes;
phenomena incomparably the most violent that
now appear upon the surface of our planet.*
The evidence of design in the employment of
forces, which have thus effected a grand general
purpose, viz. that of forming dry land, by elevating
strata from beneath the waters in which
they were deposited, stands independent of the
truth or error of contending theories, respecting
the origin of that most ancient class of stratified
rocks, which are destitute of organic remains
(see pi. 1 .— section 1 , 2 , 3 ,4 ,5 ,6 , 7). It is
* 4 The fact of great and frequent alteration in the relative level
of the sea and land is so well established, that the only remaining
questions regard the mode in which these alterations have
been effected, whether by elevation of the land itself, or subsidence
in the level of the sea? And the nature of the force
which has produced them ? The evidence in proof of great and
frequent movements of the land itself, both by protrusion and
subsidence, and of the connection of these movements with the
operations of volcanos, is so various and so strong, derived from
so many different quarters on the surface of the globe, and every
day so much extended by recent enquiry, as almost to demonstrate
that these have been the causes by which those great revolutions
were effected ; and that although the action of the inward
forces which protrude the land has varied greatly in different
countries, and at different periods, they are now and ever
have been incessantly at work in operating present change and
preparing the way for future alteration in the exterior of the
globe.’’—Geological Sketch of the Vicinity of Hastings, by Dr.
Fitton, pp. 85, 86.