

322 VALLEY OF TIIE EIO DEL NORTE. 



knot, or widening of the Cordilleras, is that the grouping of 

 the summits is independent of the general direction of the 

 axis. The backs of the mountains in New Spain form very 

 elevated plains, along which carriages can roll for an extent 

 of 400 leagues, from the capital to Santa-Fe and Taos, near 

 the sources of Rio del ISTorte. This immense table-land, in 

 19 and 24-i- is constantly at the height of from 950 to 

 1200 toises, that is, at the elevation of the passes of the 

 Great Saint Bernard and the Spliigen. "We find on the 

 back of the Cordilleras of Anahuac, which lower progressively 

 from the city oi Mexico towards Taos, a succession of basins: 

 they are separated by hills little striking to the eye of the 

 traveller because they rise only from 250 to 400 toises above 

 the surrounding plains. The basins are sometimes closed, 

 like the valley of Tenochtitlan, where lie the great Alpine 

 lakes, and sometimes they exhibit traces of ancient ejections, 

 destitute of water. 



Between lat. 33 and 38, the Eio del Norte forms, in its 

 upper course, a great longitudinal valley; and the central 

 chain seems here to be divided into several parallel ranges. 

 This distribution continues northward, in the Eocky Moun- 

 tains,* where, between the parallels of 37 and 41, several 

 summits covered with eternal snow (Spanish Peak, James 

 Peak, and Big Horn), are from 1600 to 1870 toises of abso- 

 lute height. Towards lat. 40 south of the sources of the 

 Paduca, a tributary of the Eio de la Plata, a branch known 

 by the name of the Black Hills, detaches itself towards the 

 north-east from the central chain. The Eocky Mountains 

 at first seem to lower considerably in 46 and 48 ; and then 

 rise to 48 and 49, where their tops are from 1200 to 1300 

 toises, and their ridge near 950 toises. Between the sources 

 of the Missouri and the Eiver Lewis, one of the tributaries 

 of the Oregon or Columbia, the Cordilleras form in widening, 

 an elbow resembling the knot of Cuzco. There, also, on the 

 eastern declivity of the Eocky Mountains, is the partition of 

 water between the Caribbean Sea and the Polar Sea. This 

 point corresponds with those in the Andes of South America, 

 at the spur of Cochabamba, on the east, lat. 19 20' south ; 



* The Rocky Mountains have been at different periods designated by 

 the names of Chypewyan, Missouri, Columbian, Caous, Stony, Shining, 

 and Sandy Mountains. 



