indebted for the idea of the immensity of
the duration of time. He was the forerunner of Lyell and of the
uniformitarian school of geologists.

Hutton observed that fossils characterized certain strata, but the value
of fossils as time-marks and the principle of the superposition of
stratified fossiliferous rocks were still more clearly established by
William Smith, an English surveyor, in 1790. Meanwhile the Abbe Hauey,
the founder of crystallography, was in 1802 Professor of Mineralogy in
the Jardin des Plantes.

_Lamarck's Contributions to Physical Geology; his Theory of the Earth._

Such were the amount and kind of knowledge regarding the origin and
structure of our earth which existed at the close of the eighteenth
century, while Lamarck was meditating his _Hydrogeologie_, and had begun
to study the invertebrate fossils of the Paris tertiary basin.

His object, he says in his work, is to present certain considerations
which he believed to be new and of the first order, which had escaped
the notice of physicists, and which seemed to him should serve as the
foundations for a good theory of the earth. His theses are:

1. What are the natural consequences of the influence and the
movements of the waters on the surface of the globe?

2. Why does the sea constantly occupy a basin within the limits
which contain it, and there separate the dry parts of the surface of
the globe always projecting above it?

3. Has the ocean basin always existed where we actually see it, and
if we find proofs of the sojourn of the sea in places where it no
longer remains, by what cause was it found there, and why is it no
longer there?

4. What influence have living bodies exerted on the substances found
on the surface of the earth and which compose the crust which
invests it, and what are the general results of this influence?

Lamarck then disclaims any intentions of framing brilliant hypotheses
based on supposititious principles, but nevertheless, as we shall see,
he falls into this same error, and like others of his period makes some
preposterous hypotheses, though these are far less so than those of
Cuvier's _Discours_. He distinguishes between the action of rivers or of
fresh-water currents, torrents, storms, the melting of snow, and the
work of the ocean. The rivers wear away and bear materials from the
highlands to the lowlands, so that the plains are gradually elevated;
ravines form and become imme