102 LAMARCK, HIS LIFE AND WORK 



part of it ; hence what in this case are the summits 

 of the mountains are only the remains of the former 

 level of the plain unless the process of washing away 

 and other means of degradation have not since re- 

 duced its height." 



Now this will apply perfectly well to our table- 

 lands, mesas, the mountains of our bad-lands, even 

 to our Catskills and to many elevations of this nature 

 in France and in northern Africa. But Lamarck un- 

 fortunately does not stop here, but with the zeal of 

 an innovator, by no means confined to his time alone, 

 claims that the mountain masses of the Alps and the 

 Andes were carved out of plains which had been 

 raised above the sea-level to the present heights of 

 those mountains. 



Two causes, he says, have concurred in forming 

 these elevated plains. 



" One consists in the continual accumulation of 

 material filling the portion of the ocean-basin from 

 which the same seas slowly retreat ; for it does not 

 abandon those parts of the ocean-basin which are sit- 

 uated nearer and nearer to the shores that it tends to 

 leave, until after having filled its bottom and having 

 gradually raised it. It follows that the coasts which 

 the sea is abandoning are never made by a very deep- 

 lying formation, however often it appears to be such, 

 for they are continually elevated as the result of the 

 perpetual balancing of the sea, which casts off from 

 its shores all the sediments brought down by the riv- 

 ers ; in such a way that the great depths of the ocean 

 are not near the shore from which the sea retreats, 

 but out in the middle of the ocean and near the op- 

 posite shores which the sea tends to invade. 



" The other cause, as we shall see, is found in the 



