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 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 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 geography 

 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 



