The natural belief on this subject doubtless is, that the world,
such as we now see it, possessed its present form and configuration
from the beginning. Nothing can be more natural than the belief
that the present continents and oceans have always been where
they are now; that we have always had the same mountains and
plains; that our rivers have always had their present courses,
and our lakes their present positions; that our climate has always
been the same; and that our animals and plants have always been
identical with those now familiar to us. Nothing could be more
natural than such a belief, and nothing could be further removed
from the actual truth. On the contrary, a very slight acquaintance
with geology shows us, in the words of Sir John Herschel, that
"the actual configuration of our continents and islands, the
coast-lines of our maps, the direction and elevation of our
mountain-chains, the courses of our rivers, and the soundings
of our oceans, are not things primordially arranged in the
construction of our globe, but results of successive and complex
actions on a former state of things; _that_, again, of similar
actions on another still more remote; and so on, till the original
and really permanent state is pushed altogether out of sight
and beyond the reach even of imagination; while on the other
hand, a similar, and, as far as we can see, interminable vista
is opened out for the future, by which the habitability of our
planet is secured amid the total abolition on it of the present
theatres of terrestrial life."

Geology, then, teaches us that the physical features which now
distinguish the earth's surface have been produced as the ultimate
result of an almost endless succession of precedent changes.