ies in Russia and in North America, do not support the view, that
the older a formation is, the more it has always 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 {309} 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 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 palaeozoic or secondary formation.
Hence we may perhaps infer, that during the palaeozoic and secondary
periods, neither continents nor continental islands existed where our
oceans now extend; for had they existed there, palaeozoic 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 oscillations of level, which we may fairly conclude must
have intervened during these enormously long periods. If then we may infer
anything from these facts, we may infer that where our oceans now extend,
oceans have extended from the remotest period of which we have any record;
and on the other hand, that where continents now exist, large tracts of
land have existed, subjected no doubt to great oscillations of level, since
the earliest silurian period. The coloured map appended to my volume on
Coral Reefs, led me to conclude that the great oceans are still mainly
areas of {310} subsidence, the great archipelagoes still areas of
oscillations of level, and the continents areas of elevation. But have we
any right to assume