Missouri, etc.

He then distinguishes between granitic or crystalline mountains, and
those composed of stratified rocks and volcanic mountains.

The erosive action of rivers is thus discussed; they tend first, he
says, to fill up the ocean basins, and second, to make the surface of
the land broken and mountainous, by excavating and furrowing the plains.

Our author did not at all understand the causes of the inclination or
tilting up of strata. Little close observation or field work had yet
been done, and the rocks about Paris are but slightly if at all
disturbed. He attributes the dipping down of strata to the inclination
of the shores of the sea, though he adds that nevertheless it is often
due to local subsidences. And then he remarks that "indeed in many
mountains, and especially in the Pyrenees, in the very centre of these
mountains, we observe that the strata are for the most part either
vertical or so inclined that they more or less approach this direction."

"But," he asks, "should we conclude from this that there has
necessarily occurred a universal catastrophe, a general overturning?
This assumption, so convenient for those naturalists who would
explain all the facts of this kind without taking the trouble to
observe and study the course which nature follows, is not at all
necessary here; for it is easy to conceive that the inclined
direction of the beds in the mountains may have been produced by
other causes, and especially by causes more natural and less
hypothetical than a general overturning of strata."

While streams of fresh water tend to fill up and destroy the ocean
basins, he also insists that the movements of the sea, such as the
tides, currents, storms, submarine volcanoes, etc., on the contrary,
tend to unceasingly excavate and reestablish these basins. Of course we
now know that tides and currents have no effect in the ocean depths,
though their scouring effects near shore in shallow waters have locally
had a marked effect in changing the relations of land and sea. Lamarck
went so far as to insist that the ocean basin owes its existence and its
preservation to the scouring action of the tides and currents.

The earth's interior was, in Lamarck's opinion, solid, formed of
quartzose and silicious rocks, and its centre of gravity did not
coincide with its geographical centre, or what he calls the _centre de
forme_. He imagined also that the ocean revolved around the globe from