re generally
arranged in more or less regular chains. But he strangely assumes that
the constituents of granite, _i.e._, felspar, quartz, and mica, did not
exist before vegetables, and that these minerals and their aggregation
into granite were the result of slow deposition in the ocean.[80] He
goes so far as to assert that the porphyritic rocks were not thus formed
in the sea, but that they are the result of deposits carried down by
streams, especially torrents flowing down from mountains. Gneiss, he
thinks, resulted from the detritus of granitic rocks, by means of an
inappreciable cement, and formed in a way analogous to that of the
porphyries.

Then he attacks the notion of Leibnitz of a liquid globe, in which all
mineral substances were precipitated tumultuously, replacing this idea
by his chemical notion of the origin of the crystalline and volcanic
rocks.

He is on firmer ground in explaining the origin of chalk and clay, for
the rocks of the region about Paris, with which he was familiar, are
sedimentary and largely of organic origin.

In the "Addition" (pp. 173-188) following the fourth chapter Lamarck
states that, allowing for the variations in the intensity of the cause
of elevation of the land as the result of the accumulations of organic
matter, he thinks he can, without great error, consider the mean rate as
324 mm. (1 foot) a century. As a concrete example it has been observed,
he says, that one river valley has risen a foot higher in the space of
eleven years.

Passing by his speculations on the displacement of the poles of the
earth, and on the elevations of the equatorial regions, which will
dispense with the necessity of considering the earth as originally in a
liquid condition, he allows that "the terrestrial globe is not at all a
body entirely and truly solid, but that it is a combination (_reunion_)
of bodies more or less solid, displaceable in their mass or in their
separate parts, and among which there is a great number which undergo
continual changes in condition."

It was, of course, too early in the history of geology for Lamarck to
seize hold of the fact, now so well known, that the highest mountain
ranges, as the Alps, Pyrenees, the Caucasus, Atlas ranges, and the
Mountains of the Moon (he does not mention the Himalayas) are the
youngest, and that the lowest mountains, especially those in the more
northern parts of the continents, are but the roots or remains of what
were originally lo