Having discussed those vague analogies and fanciful pedigrees by which
it has been attempted to drag the science of Biology into the service
of Agnostic Evolution, we may now turn to another science--that of the
earth--and inquire how far it justifies us in affirming the
spontaneous evolution of plants and animals in the progress of
geological time. This subject is one which would require a lengthy
treatise for its full development, and it cannot be pursued in the
most satisfactory way without much previous knowledge of geological
facts and principles, and of the classification of animals and plants.
On the present occasion it must therefore be treated in the most
general possible manner, and with reference merely to the results
which have been reached. There is the more excuse for this mode of
treatment that, in works already published and widely circulated,[7]
I have endeavored to present its details in a popular form to general
readers.
Geological investigation has disclosed a great series of stratified
rocks composing the crust of the earth, and formed at successive
times, chiefly by the agency of water. These can be arranged in
chronological order; and, so arranged, they constitute the physical
monuments of the earth's history. We must here take for granted, on
the testimony of geology, that the accumulation of this series of
deposits has extended over a vast lapse of time, and that the
successive formations contain remains of animals and plants from which
we can learn much as to the succession of life on the earth. Without
entering into geological details, it may be sufficient to present in
tabular form (see p. 107) the grand series of formations, with the
general history of life as ascertained from them.