480 



Lat. 16° 18°. Mountains of gneiss-granite in 

 the province of Oaxaca. 



Lat. 181°-19i°. Trachytic knot of Anahuac, 

 parallel to the Nevados and the burning vol- 

 canoes of Mexico. 



Lat. 192°-20°. Knot of metaliferous moun- 

 tains of Guanaxuato and Zacatecas. 



Lat. 21|-22'. Division of the Andes of Ana- 

 huac into three chains : 



Eastern chain (of Potosi and Texas), conti- 

 nued by the mountains Ozark and Wiscon- 

 san, as far as Lake Superior. 



Central chain (of Durango, New Mexico, and 

 the Rocky Mountains,) sending, on the 

 north of the source of the river Platte (lat. 

 42°), a branch (the Cotes Noires) towards 

 the N. E., widening greatly between the 

 parallels 46° and 50°, and lowering pro- 

 gressively as it draws near the mouth of 

 Mackenzie river (lat. 68°). 



Western chain (of Cinaloa and Sonora). It 

 is linked by counter-forts to the maritime 

 Alps, or mountains of California. 



We have yet no means of judging with 

 precision the elevation of the Andes on the 

 south of the knot of the mountains of Loxa 

 (south lat. 3° - 5°) ; but we know that on the 

 north of that knot, the Cordilleras rise five 

 times above the majestic height of 2600 toises : 



