two indefinite points has
been regarded as liable to constant interruption by revolutions
and catastrophes of different kinds, in many cases emanating from
supernatural sources. Few of the more ancient theological creeds,
and still fewer of the ancient philosophies, attained body and
shape without containing, in some form or another, the belief
in the existence of periodical convulsions, and of alternating
cycles of destruction and repair.

That geology, in its early infancy, should have become imbued
with the spirit of this belief, is no more than might have been
expected; and hence arose the at one time powerful and
generally-accepted doctrine of "Catastrophism." That the succession
of phenomena upon the globe, whereby the earth's crust had assumed
the configuration and composition which we find it to possess,
had been a discontinuous and broken succession, was the almost
inevitable conclusion of the older geologists. Everywhere in
their study of the rocks they met with apparently impassable
gaps, and breaches of continuity that could not be bridged over.
Everywhere they found themselves conducted abruptly from one system
of deposits to others totally different in mineral character or
in stratigraphical position. Everywhere they discovered that
well-marked and easily recognisable groups of animals and plants
were succeeded, without the intermediation of any obvious lapse
of time, by other assemblages of organic beings of a different
character. Everywhere they found evidence that the earth's crust
had undergone changes of such magnitude as to render it seemingly
irrational to suppose that they could have been produced by any
process now in existence. If we add to the above the prevalent
belief of the time as to the comparative brevity of the period
which had elapsed since the birth of the globe, we can readily
understand the general acceptance of some form of catastrophism
amongst the earlier geologists.

As regards its general sense and substance, the doctrine of
catastrophism held that the history of the earth, since first
it emerged from the primitive chaos, had been one of periods
of repose, alternating with catastrophes and cataclysms of a
more or less violent character. The periods of tranquillity were
supposed to have been long and protracted; and during each of them
it was thought that one of the great geological "formations" was
deposited. In each of these periods, therefore, the condition of
the earth wa