384 COSMOS. 



the neighborhood of Albuquerque, and at this bifurcation the 

 western chain still maintains the general title of the Sierra 

 Madre, while the eastern branch has received from lat. 36° 

 10^ forward (a lit-tle to the north of Santa Fe), from Amer- 

 ican and English travelers, the equally ill-chosen, but now 



Mississippi mix cotes de V Or/can Pacijique^ p. 113-116; also in t\ie, Bul- 

 letin de la Socicte Geologique de la France, 2e Serie, t. xii., p. 813. In 

 the elongated valley closed by the Sierra Madre, or Rocky Mountains, 

 lat. 35° 38|-°, the separate groups of which the western chain of the 

 Sierra Madre and the eastern chain of the Rocky Mountains (Sierra 

 de Sandia) consist, bear different names. To the first chain belong, 

 reckoning from south to north, the Sierra de las Grullas, the S. de 

 los Mimbres (Wislizenus, p. 22 and 54), Mount Taylor (lat. 35° 15'), 

 the S. de Jemez, and the S. de San Juan ; in the eastern chain the 

 Moro Peaks, or Sierra de la Sangre de Cristo, are distinguished from 

 the Spanish Peaks (lat. 37° 32') and th& noithwesterly tending White 

 Mountains, which close the elongated valley of Taos and Santa Ee. 

 Professor Julius Frobel, whose examination of the volcanoes of Cen- 

 tral America I have already noticed {Cosmos, above, p. 260), has with 

 much ability elucidated the indefinite geographical appellation of Si- 

 erra Madre on the older maps ; but he has at the same time, in a treat- 

 ise entitled Remarks contributing to the Physical Geography of the North 

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

 1855, p. 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 con- 

 tinuation of the Mexican mountain range in the tropical* zone of Ana- 

 huac. 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 S.S.E. to N.N.W. ; 

 but the immense swelling of the surface of the land, which goes on in- 

 creasing in breadth toward the north and northwest, 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 diffbrent periods. These snper- 

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

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

 like a rampai-t, and rendered visible to a great distance by conical 

 mountains, chiefly trachytic, from 10,000 to 12,000 feet high, produce 

 an impression on the mind of the traveler which is only the more pro- 

 found from the circumstance that the elevated plateau which stretches 

 far and wide aj^ound 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 in- 

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

 expression Las Cordilleras de los Ailftcs refers to such a disposition and 

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

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

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

 other or to the direction of the entire swell of the land. 



