as advocated hy M. Elie de Beaumont, 1 27 



number of elevations that we differ, and I confess I have less 

 faith in the present state of our knowledge. To those philoso- 

 phers who, on the other hand, suppose an unlimited number of 

 epochs of elevation, we would, with M. de Beaumont, oppose 

 the logical deduction of Saussure and M. Brochant, viz. that 

 " La Constance de direction des couches redressdes dans un cer- 

 tain ensemble de montagne ou de terrain doit probablement re- 

 sulter de ce que toutes ces masses ont ete deplacees, en meme 

 temps par la meme operation naturelle." — (Btdlet, Univ. de Sc. 

 Nat. vol. xxi. p. 344.) Now, as these groups of deposits are 

 limited in number, in proportion to the small surface of our 

 planet, the opinion of an unlimited number of very great ele- 

 vations would seem to be excluded. 



M. de Beaumont believes that, in his system, he has given 

 more than des apercus generaux et vugues, in regard to the mu- 

 tual relations of elevations and geological formations (p. 621); 

 but I believe with my excellent friend Mr Lyell, that he exag- 

 gerates the results of his views ; for, speaking only of Europe, 

 he considers merely the chains of mountains, and what he calls 

 boutonnieres. He has not yet ventured to trace, upon a map 

 of Europe, his twelve systems of elevations, although the facts 

 for such a generalization are not wanting. But, as such a map 

 is more striking than long descriptions, errors are more easily 

 perceived even by those who are not initiated in all the details of 

 geological geography, and in such a case retractations are more 

 painful. 



In order to have given something more than limited views, 

 M. de Beaumont should have added to his ideas on the forma- 

 tions of mountain chains, and their directions, some considera- 

 tions on the formation of table-lands and plains or flat countries, 

 and also a greater number of geological and geogenical exposi- 

 tions, similar to those I offered on the nature and origin of the 

 European formations, (Memoires Geolog. et, Paleontol. 1832). 

 By followingthis plan, his essay would have been complete, while, 

 as it is, it cannot be considered as more than "des apercus generaux 

 et vagues ;" for the respective geographical limits of his systems 

 are not all traced ; whereas, according to my way of considering 

 and describing the geogeny of the crust of the earth, that of 

 taking formation after formation, every tolerably accurate map 



