TRUE VOLCANOES. 413 



decreases to a more regular level. Clarke's Fork and Lewis 

 or Snake River unite in forming the great Columbia River, 

 which will one day prove an important channel for com- 

 merce. (Explorations for a railroad from tlie Mississippi 

 River to the Pacific Ocean, made in 1853 1854, vol. i, p. 

 107.) 



As in Bolivia, the eastern chain of the Andes furthest 

 removed from the sea, that of Sorata (21,287 feet) and 

 Illimani (21,148 feet), furnish no volcano now in a state 

 of ignition, so also in the western parts of the United 

 States, the volcanic action on the coast-chain of California 

 and Oregon is at present very limited. The long chain of 

 the Rocky Mountains, at a distance from the shores of the 

 South Sea varying from 480 to 800 geographical miles, 

 without any trace of still existing volcanic action, neverthe- 

 less shows, like the eastern chain of Bolivia in the vale of 

 Yucay, 18 on both of its slopes volcanic rock, extinct craters, 

 and even lavas inclosing obsidian, and beds of scoriae. In 

 the chain of the Rocky Mountains which we have here 

 geographically described in accordance with the admirable 

 observations of Fremont, Emory, Abbot, Wislizenus, Dana, 

 and Jules Marcou, the latter, a distinguished geologist, 

 reckons three groups of old volcanic rock on the two slopes. 

 For the earliest notices of the vulcanicity of this district we 

 are- also indebted to the investigations made by Fremont 

 since the years 1842 and 1843 (Report of the Exploring Ex- 

 pedition to the Rocky Mountains in 1842, and to Oregon and 

 North California in 1843-44, pp. 164, 184-187, and 193). 



On the eastern slope of the Rocky Mountains, on the 

 south-western road from Bent's Fort, on the Arkansas River 

 to Santa Fe del Nuevo Mexico, lie two extinct volcanoes, the 

 Raton Mountains 19 with Fisher's Peak, and the hill of El 

 Cerrito between Galisteo and Pcna Blanca. The lavas of the 

 former cover the whole district between the Upper Arkansas 

 and the Canadian River. The Peperino and the volcanic 

 sconce, which are first met with even in the prairies, on 



18 See above p. 295. 



19 According to the road-map of 1855, attached to the general repor 1 ; 

 of the Secretary of State, Jefferson Davis, the Raton Pass rises to an 

 elevation of as much as 7180 feet above the level of the sea. Compare, 

 also, Marcou, Resume explicatif d'une Carte GcoL, 1855, p. 113. 



