302 On the relative Age of' the 



same circle, have probably perforated the crust of the globe at 

 the same time as Mont Blanc. 



For the fourth and last system of which M. de Beaumont 

 has spoken, the great circle of comparison passes through the 

 Empire of Morocco and the eastern extremity of the Himalayan 

 mountains. The parallelism has been verified on the Ventoux 

 and Leberon mountains near Avignon ; the Saintc-Baume and 

 many other chains in Provence ; and, lastly, the central chain of 

 the Alps, from the Valais to Styria. If parallehsm be here also 

 an indication of the date, as there is every reason to believe, we 

 might refer to this comporativcly modern system of mountain.s 

 the Balkan, the great porphyritic central chain of the Caucasus, 

 the Himalayan mountains and the Atlas I'ange. 



There is an immense chain of mountains, the most extensive 

 in the world, which, from its direction, cannot be referred to 

 any of the systems above described. This chain is the great 

 American Cordillera. In the deficiency of satisfactory geologi- 

 cal observations, M. de Beaumont has indulged in conjectures 

 from which it would seem, with some degree of probability, to 

 result, that this great chain is newer than the fourth of these 

 systems. These conjectures, however ingenious they may be, 

 are too much out of the limit within which I would confine my- 

 self, to be given here. Besides, I should apprehend that inat- 

 tentive persons might confound them with the strict inductions 

 of which I have presented an account, and thus fall into error. 

 I therefore hasten to conclude this article, which, however, I 

 cannot do without remarking how much the purely geographi- 

 cal study of the chains of mountains will be simplified, when 

 the parallelism supposed by M. de Beaumont as a distinctive 

 character of contemporaneous mountains, having been directly 

 verified in the most distant points in the Himalayan range, for 

 example, compared with Mont Ventoux, will take its place 

 among the principles of science. Simple classifications, capable 

 of being retained by the most treacherous memories, and free 

 of every thing arbitrary, as the order of antiquity will be that 

 followed, will then guide us through the inextricable labyrinth 

 of intersecting chains, of which no geographer has as yet been 

 able to present a perfectly satisfactory picture. 



Since the results obtained by M. de Beaumont have been 



