50 



the latter appear to have been successively formed 

 by the agency of its waters. 



The interior structure of the Andes every 

 where exhibits a very different origin, and ap- 

 pears to be coeval with the creation of the w orld. 

 This immense mountain, rising- abruptly, forms 

 but a small angle with its base ; its general shape 

 is that of a pyramid, crowned at intervals with 

 conical, and, as it were, crystallized elavations. 

 It is composed of primitive rocks of quartz of an 

 enormous size and almost uniform contiguration, 

 containing no marine substances, which abound 

 in the secondary mountains. On the top of 

 Descabezado, a very lofty mountain in the midst 

 of the principal chain of the Andes, whose 

 height appears to me not inferior to that of the 

 celebrated Chimboraso of Quito, various shells, 

 evidently the production of the sea, oysters, 

 conchs, periwinkles, &c. are found in a calcii.ed 

 or petrified state, that Nvere doubtless deposited 

 there by the waters of the deluge. 



The summit of this mountain, whose form 

 appears to be owing to some volcanic eruption, 

 is flat, and exhibits a plain of tnore than six 

 miles square ; in the middle is a very deep lake, 

 Mhich, from every appearance, was formerly the 

 crater (;f a volcano. 



The [iriiicipal chain of the Andes is situated 

 between two of less height that are parallel to 

 it. These lalcrai chains are about twentv-tive 



