HYPSOMETRIC ADDENDA. 223 



or 5330 and 7460 English feet above the level of the sea) to the 

 highland of which I have just given the levelling, and yet over which 

 four-wheeled wagons can travel as they do from Mexico to Santa FC*. 

 It is formed by the broad, undulating, flattened crest of the chain of 

 the Mexican Andes, and is not the swelling of a valley between two 

 mountain chains, as is the case in some other remarkable elevations 

 of plain or undulating surface in the Northern Hemisphere, in the 

 " Great Basin" between the Kocky Mountains and the Sierra Nevada 

 of California, in the Southern Hemisphere, in the high plain of 

 the Lake of Titicaca, between the eastern and western chains of the 

 Andes of Bolivia, and in Asia, in the highlands of Thibet, between 

 the Himalaya and the Kuen-liin. 





