On the other hand, as long as the bed of the sea remained
stationary, THICK deposits could not have been accumulated in the
shallow parts, which are the most favourable to life. Still less could
this have happened during the alternate periods of elevation; or, to
speak more accurately, the beds which were then accumulated will have
been destroyed by being upraised and brought within the limits of the
coast-action.
Thus the geological record will almost necessarily be rendered
intermittent. I feel much confidence in the truth of these views, for
they are in strict accordance with the general principles inculcated
by Sir C. Lyell; and E. Forbes independently arrived at a similar
conclusion.
One remark is here worth a passing notice. During periods of elevation
the area of the land and of the adjoining shoal parts of the sea will
be increased, and new stations will often be formed;--all
circumstances most favourable, as previously explained, for the
formation of new varieties and species; but during such periods there
will generally be a blank in the geological record. On the other hand,
during subsidence, the inhabited area and number of inhabitants will
decrease (excepting the productions on the shores of a continent when
first broken up into an archipelago), and consequently during
subsidence, though there will be much extinction, fewer new varieties
or species will be formed; and it is during these very periods of
subsidence, that our great deposits rich in fossils have been
accumulated.
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