extent
of the marine deposits of Italy. These early cultivators of geology soon
perceived the advantage to be gained by the establishment of museums and
the publication of catalogues. The first seems to have been that of John
Kentman, an example that was followed by Calceolarius and Vallisneri.
Subsequently Fontanelle proposed the construction of charts in
accordance with fossil remains; but the principle involved was not
applied on the great scale as a true geological test until introduced by
Smith in connexion with the English strata.

[Sidenote: The pre-organic time.] To Steno, a Dane, is due the
recognition of pre-organic in contradistinction to organic rocks, a
distinction the terms of which necessarily involve the idea of time.
Soon it became generally recognized that the strata in which organic
remains occur are of a later date than those devoid of them, the
pre-organic rocks demonstrating a pre-organic time. Moreover, as facts
were developed, it was plain that there are essential differences in the
relations of fossils, and that, though in Italy the same species of
shells may occur in the mountains that occur in the adjacent seas, this
was very far from being the case uniformly elsewhere. At length the
truth began to emerge, that in proportion as the strata under
examination are of an older date, so are the differences between their
organic remains and existing species more marked. It was also discovered
that the same species often extends superficially over immense
districts, but that in a vertical examination one species after another
rapidly appears in a descending order--an order which could be verified
in spite of the contortions, fractures, and displacements of the strata.
A very important theoretical conclusion was here presented: for the
rapid succession of essentially different organic forms, as the rocks
were older, was clearly altogether inconsistent with one catastrophe, as
the universal deluge, to which it had been generally referred. It was
plain that the thickness of the strata in which they were enveloped, and
the prodigious numbers in which they occurred, answered in some degree
to the period of life of those fossils, since every one of them, large
or small, must have had its time of birth, of maturity, and of death.
[Sidenote: Insufficiency of a single catastrophe.] When, therefore, it
could be no longer doubted that strata many hundreds of feet in
thickness were crowded with such remains, it b