r element, have been left to
perish from drought.

Even ancient rocks formed or deposited before the appearance of life on
the earth show signs of terrific violence.

It has been maintained by some that the causes now at work altering the
face of the world are sufficient to account for all the changes through
which it has passed: but that is not so. None of the agents Nature now
employs--rain, thaw, rivers, seas, volcanoes--would have been adequate
to produce her ancient works.

To explain the external crust of the world, we require causes other than
those present in operation, and a thousand extraordinary theories have
been advanced. Thus, according to one philosopher, the earth has
received in the beginning a uniform light crust which caused the abysses
of the ocean, and was broken to produce the Deluge. Another supposed the
Deluge to be caused by the momentary suspension of the cohesion of
minerals.

Even accomplished scientists and philosophers have advanced impossible
and contradictory theories.

All attempts at explanation have been stultified by an ignorance of the
facts to be explained, or by a partial survey of them, and especially by
a neglect of the evidence afforded by fossils. How was it possible not
to perceive that the theory of the earth owes its origin to fossils
alone? They alone, in truth, inform us with any certainty that the earth
has not always had the same covering, since they certainly must have
lived upon its surface before they were buried in its depths. If there
were only strata without fossils, one might maintain that the strata had
all been formed together. Hitherto, in fact, philosophers have been at
variance on every point save one, and that is that the sea has changed
its bed; and how could this have been known except for fossils?

From this consideration I was led to study fossils; and since the field
was immense I was obliged to specialise in one department of fossils,
and selected for study the fossil bones of quadrupeds. I made this
selection because only from a study of fossil quadrupeds can one hope to
ascertain the number and periods and contents of irruptions of the sea;
and because, since the number of quadrupeds is limited, and most
quadrupeds known, we have better means of assuring ourselves if the
fossil remains are remains of extinct or extant animals. Animals such as
the griffin, the cartazonon, the unicorn, never lived, and there are
probably very few quadrupeds now