with new and peculiar species. Traces of life have been detected in the
Longmynd beds beneath Barrande s so-called primordial zone. The
presence of phosphatic nodules and bituminous matter in some of the
lowest azoic rocks, probably indicates the former existence of life at
these periods. But the difficulty of understanding the absence of vast
piles of fossiliferous strata, which on my theory no doubt were
somewhere accumulated before the Silurian epoch, is very great. If
these most ancient beds had been wholly worn away by denudation, or
obliterated by metamorphic action, we ought to find only small remnants
of the formations next succeeding them in age, and these ought to be
very generally in
a metamorphosed condition. But the descriptions which we now possess of
the Silurian deposits over immense territories in Russia and in North
America, do not support the view, that the older a formation is, the
more it has suffered the extremity of denudation and metamorphism.
The case at present must remain inexplicable; and may be truly urged as
a valid argument against the views here entertained. To show that it
may hereafter receive some explanation, I will give the following
hypothesis. From the nature of the organic remains, which do not appear
to have inhabited profound depths, in the several formations of Europe
and of the United States; and from the amount of sediment, miles in
thickness, of which the formations are composed, we may infer that from
first to last large islands or tracts of land, whence the sediment was
derived, occurred in the neighbourhood of the existing continents of
Europe and North America. But we do not know what was the state of
things in the intervals between the successive formations; whether
Europe and the United States during these intervals existed as dry
land, or as a submarine surface near land, on which sediment was not
deposited, or again as the bed of an open and unfathomable sea.
Looking to the existing oceans, which are thrice as extensive as the
land, we see them studded with many islands; but not one oceanic island
is as yet known to afford even a remnant of any pal ozoic or secondary
formation. Hence we may perhaps infer, that during the pal ozoic and
secondary periods, neither continents nor continental islands existed
where our oceans now extend; for had they existed there, pal ozoic and
secondary formations would in all probability have been accumulated
from sediment derived from their wear and
tear; and would have been at least partially upheaved by the
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