resent history of the
earth, had almost completely triumphed over the older catastrophic
views. As Huxley put it, the school of catastrophe put no limit to the
violence of forces which had operated; the uniformitarians put no limit
to the length of time during which forces had operated.

"Catastrophism has insisted upon the existence of a practically
unlimited bank of force, on which the theorist might draw; and it
has cherished the idea of development of the earth from a state
in which its form, and the forces which it exerted, were very
different from those which we now know.

"Uniformitarianism, on the other hand, has with equal justice
insisted upon a practically unlimited bank of time, ready to
discount any quantity of hypothetical paper. It has kept before
our eyes the power of the infinitely little, time being granted,
and has compelled us to exhaust known causes before flying to the
unknown."

But there was a third influence at work in geology, an influence which
may best be described in Huxley's own words:

"I shall not make what I have to say on this head clear unless I
diverge, or seem to diverge, for a while, from the direct path of
my discourse so far as to explain what I take to be the scope of
geology itself. I conceive geology to be the history of the
earth, in precisely the same sense as biology is the history of
living beings; and I trust you will not think that I am
overpowered by the influence of a dominant pursuit if I say that
I trace a close analogy between these two histories.

"If I study a living being, under what heads does the knowledge
I obtain fall? I can learn its structure, or what we call its
Anatomy; and its development, or the series of changes it passes
through to acquire its complete structure. Then I find that the
living being has certain powers resulting from its own
activities, and the interaction of these with the activities of
other things--the knowledge of which is Physiology. Beyond this,
the living being has a position in space and time, which is its
Distribution. All these form the body of ascertainable facts
which constitute the _status quo_ of the living creature. But
these facts have their causes; and the ascertainment of these
causes is the doctrine of AEtiology.

"If we consider what is knowable about t