1842.] of the Himmalay a Mountains. cxlvii 



endless and complicated ramifications, the ragged and steep acclivities, 

 the total absence of vallies or level ground, the lofty summits and deep 

 ravines there described, we have in the latter an arrangement of two 

 parallel chains or ridges running for a distance of 500 miles, and en- 

 closing between them a broad and elevated table land, constituting one 

 of the finest countries in the world ; again the numerous volcanoes, ex- 

 tinct or igneous of the Andes, the terrible earthquakes, the torrents 

 of mud and water so frequently discharged from openings suddenly 

 occurring, and the uprising of considerable mountains ; all these circum- 

 stances belong to a totally different order of things from that which 

 prevails in the Himmalaya. 



311. The difference in physical features is not greater than that 

 which appears in the geological character of these two rival chains. In 

 the Andes, as we learn from Humboldt, there is an extraordinary deve- 

 lopement of porphyry and trachyte, the more elevated points being 

 composed almost exclusively of the latter rock. Trachyte is confessedly 

 a volcanic production, though the rival schools are at variance with re- 

 gard to porphyry. Yet, M. Humboldt in his latest work, appears to 

 incline to the opinion of its also being of igneous origin.* We may 

 further notice the great deficiency of primary formations. f Granite and 

 gneiss are only found in masses of any extent near the sea coast and at 

 low elevations, while the transition clay slates and secondary sandstones 

 attain a developement and an elevation, of which there are no other 

 authentic instances. 



312. In the Himmalaya again, we have seen that neither trachyte 

 nor porphyry, nor indeed any volcanic or trap rocks are to be found. 

 The whole series, as is evident from the details in Section II., is 

 composed of primary formations, and chiefly if not entirely of gneiss, 



* Or ought we not rather to admit that the domain of volcanic action has been too 

 much limited, and that these porphyries are, with respect to their origin and relative 

 age, connected with trachytes, as the trachytes formerly confounded with trap por- 

 phyries are connected with basalts, and real lava ejected by burning volcanoes? 

 Humboldt Gisement des Roches, English Translation, page 157. Again, " In Equi- 

 noxial America, the limits between transition porphyries and real trachytes known 

 to be volcanic rocks are not easy to fix." Idem, page 155. For other instances of this 

 opinion, see page 156 to 160. 



f In the Cordilleras of the Andes, of Peru, Quito, Grenada and Mexico, among 

 that innumerable variety of porphyritic rocks of which the masses attain from 2,500 

 to 3,000 toises in thickness, I did not see a single porphyry that appeared to me deci- 

 dedly primitive. Humb. Giss des Hoches, English Translation, in p. 121. 



