86 



GEOLOGY. 



Fig. 32. 



term lowland is applied to regions that are less than a 

 thousand feet above that level. The great valley of the 

 Mississippi, the plains of the Amazon, and the pampas 

 of La Plata, are examples of the latter. Plateaus some- 

 times extend between ranges. Both plateaus and low- 

 lands may have single mountains or mountain ridges. 

 The term table-land is often applied to plateaus, especial- 

 ly when their surface is little diversified. One of the 

 most elevated plateaus in the world is that of Thibet, ly- 

 ing between the Himalayas and the Kuen-Luen Mount- 

 ains, the height varying from 11,000 to 15,000 feet. The 

 State of New York is a plateau, varying in height from 

 1500 to 2500 feet. The Great Salt Lake lies in a corner 

 of a plateau by the Rocky Mountain range, which has an 

 altitude of from 4000 to 5000 feet. There are some lofty 

 plateaus in South America. The city of Quito is situa- 

 ted on a plateau at an elevation of nearly 10,000 feet, and 

 the city of Potosi on one at an elevation of 13,330 feet, 

 the Lake Titicaca being on the same plateau at the height 

 of 12,830 feet. We often see the same arrangement in 

 a small way among hills of ordinary size. An elevated 

 plain skirts a hill, or lies between hills, making a plateau 

 of small extent. There may be a pond also in such a 

 plain, like the lakes that are sometimes found in the im- 

 mense plateaus. 



