TRUE VOLCANOES. 411 



title of the Sierra Madre, while the eastern branch has re- 

 ceived from lat. 36 10' forward (a little to the north of 

 Santa Fe) from American and English travellers the equally 

 ill-chosen, but now universally accepted title of the Kocky 

 Mountains. The two chains form a lengthened valley, in 

 which Albuquerque, Santa Fe and Taos lie, and through 

 which the Rio Grande del Norte flows. In lat. 38 1 this 

 valley is closed by a chain running east and west for the 

 space of 88 geographical miles, while the rocky mountains 

 extend undivided in a meridional direction as far as lat. 41. 

 In this intermediate space rise somewhat to the east the 

 Spanish Peaks, Pike's Peak (5800 feet), which has been 



ability elucidated the indefinite geographical appellation of Sierra 

 Madre on the older maps, but he has at the same time, in a treatise 

 entitled Remarks contributing to the Physical Geography of the North 

 American Continent (9th Annual Report of the Smithsonian Institution, 

 1855, pp. 272 281), given expression to a conjecture which, after 

 having examined all the materials within my reach, I am unable to 

 assent to, namely, that the Rocky Mountains are not to be regarded as 

 a continuation of the Mexican Mountain range in the tropical zone of 

 Anahuac. Uninterrupted mountain chains, like those of the Apennines, 

 the Swiss Jura, the Pyrenees, and a great part of the German Alps, 

 certainly do not exist from the 19th to the 44th degrees of latitude, 

 from Popocatepetl in Anahuac as far as to the north of Fremont's Peak 

 in the Rocky Mountains, in the direction from SS.E. to NN.W., but the 

 immense swelling of the surface of the land which goes on increasing 

 in breadth towards the north and north-west, is continuous from 

 tropical Mexico to Oregon, and on this swelling (or elevated plain), 

 which is itself the great geognostic phenomenon, separate groups of 

 mountains, running in often varying directions, rise over fissures which 

 have been formed more recently and at different periods. These super- 

 imposed groups of mountains, which, however, in the Rocky Mountains 

 are for an extent of 8 degrees of latitude connected together almost like 

 a rampart, and rendered visible to a great distance by conical moun- 

 tains, chiefly trachytic, from 10,000 to 12,000 feet high, produce an 

 impression on the uiind of the traveller which is only the more profound 

 from the circumstance that the elevated plateau which stretches far 

 and wide around him assumes in his eyes the appearance of a plain of 

 the level country. Though in reference to the Cordilleras of South 

 America, a considerable part of which is known to me by personal 

 inspection, we speak of double and triple ranges (in fact the Spanish 

 expression las Cordilleras de los Andes refers to such a disposition and 

 partition of the chain), we must not forget that even here the direc- 

 tions of the separate ranges of mountain groups, whether in long ridges 

 or in consecutive domes, are by no means parallel, either to one 

 mother, or to the direction of the entire swell of tb land. 



