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,
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 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 Cambrian period. The coloured map appended to my volume
on Coral Reefs, led me to conclude that the great oceans are still mainly
areas of subsidence, the great archipelagoes still areas of oscillations of
level, and the continents areas of elevation. But we have no reason to
assume that things have thus remained from the beginning of the world. Our
continents seem to have been formed by a preponderance, during many
oscillations of level, of the force of elevation. But may not the areas of
preponderant movement have changed in the lapse of ages? At a period long
antecedent to the Cambrian epoch, continents may have existed where oceans
are now spread out, and clear and open oceans may have existed where our
continents now stand.
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