LAMARCK’S WORK IN GEOLOGY 105 
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 catas- 
trophe, 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 moun- 
tains may have been produced by other causes, and 
especially by causes more natural and less hypotheti- 
cal 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 reéstablish 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 preser- 
vation 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 geograph- 
ical centre, or what he calls the centre de forme. He 
imagined also that the ocean revolved around the 
globe from east to west, and that this movement, by 
