rth's surface has its special history
of elevations, subsidences, periods of rest: and this history in no case
fits chronologically with the history of any other portion. River
deltas are now being thrown down on formations of different ages: some
very ancient, some quite modern. While here there has been deposited a
series of beds many hundreds of feet thick, there has elsewhere been
deposited but a single bed of fine mud. While one region of the Earth's
crust, continuing for a vast epoch above the surface of the ocean, bears
record of no changes save those resulting from denudation; another
region of the Earth's crust gives proof of sundry changes of level, with
their several resulting masses of stratified detritus. If anything is to
be judged from current processes, we must infer, not only that
everywhere the succession of sedimentary formations differs more or less
from the succession elsewhere; but also that in each place, there exist
groups of strata to which many other places have no equivalents.

With respect to the organic bodies imbedded in formations now in
progress, a like truth is equally manifest, if not more manifest. Even
along the same coast, within moderate distances, the forms of life
differ very considerably; and they differ much more on coasts that are
remote from one another. Again, dissimilar creatures which are living
together near the same shore, do not leave their remains in the same
beds of sediment. For instance, at the bottom of the Adriatic, where the
prevailing currents cause the deposits to be here of mud, and there of
calcareous matter, it is proved that different species of co-existing
shells are being buried in these respective formations. On our own
coasts, the marine remains found a few miles from shore, in banks where
fish congregate, are different from those found close to the shore,
where littoral species flourish. A large proportion of aquatic creatures
have structures which do not admit of fossilization; while of the rest,
the great majority are destroyed, when dead, by various kinds of
scavengers. So that no one deposit near our shores can contain anything
like a true representation of the Fauna of the surrounding sea; much
less of the co-existing Faunas of other seas in the same latitude; and
still less of the Faunas of seas in distant latitudes. Were it not that
the assertion seems needful, it would be almost absurd to say, that the
organic remains now being buried in the Dogg