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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. jy 



this plain has an abundant rainfall but becomes drier to the south and 

 in Peru is a desert. In Ecuador the chief crops are sugar and cacao. 

 In Peru the agriculture is confined to the valleys that can be irrigated 

 from the mountain streams. Here the crops are sugar, cotton, grain, 

 and alfalfa. The temperature of the coastal plain is modified by the 

 Humboldt current which sweeps up from the cold Antarctic regions 

 and the coastal cities of Peru are much cooler than those of the 

 Atlantic coast in the same latitude. 



The central part of Ecuador and Peru is occupied by the great 

 Andes mountain system, the Cordillera. In a general way the system 



Fir.. 76. — A herd of llamas at Atocha, southern BoHvia. The BoHvian 

 plateau increases in aridity southward. The vegetation of the mountains in 

 the background of the scene is very sparse. The foreground is a river bed 

 that is dry, except after the infrequent hard rains. 



consists of two chains with a plateau between. In Ecuador the plateau 

 is divided into several valleys by cross ridges. In the valleys at alti- 

 tudes from 8,000 to 9,500 feet lie the chief cities, such as Tulcan, 

 Ibarra, Quito, Ambato. Riobamba, and Cuenca. In Peru the plateau is 

 at a greater altitude. South of Cuzco (11,500 feet) it broadens into a 

 wide area embracing all western Bolivia, the plateau being mostly 

 12.000 to 13,000 feet elevation for 400 miles and more than 100 

 miles wide. Most of the region above 12,000 feet is devoid of trees 

 and the plain increases in aridity southward. The southwestern part 

 of Bolivia is a desert. The plains and slopes above tree line in Ecuador 

 are called paramos and the region is called the Sierra. They are 



