282 



The Realm of Nature 



along the low plain, receiving numerous tributaries from 

 the Andes slopes on the west, and the great River Parana 

 from a southern valley of the Brazilian High Plain on the 

 east. The united river swerves eastward and enters the 

 wide shallow estuary termed the Rio de la Plata at 34 S. 

 The undulating grassy plain of its lower track is called the 

 Pampas, and is one of the flattest low plains in the 

 world. South of the La Plata several rivers flow to 

 the Atlantic from the Andes ; all are subject to floods on 

 account of the abrupt change of slope at the base of the 

 mountains, the inclination of the low plain toward the east 

 being too slight to let the water drain away when the 

 torrential track is flooded. Patagonia, the southern ex- 

 tremity of the continent, is for the most part a desert of 

 shingle, and much of it is an area of internal drainage on 

 account of the drying of the brave west winds by the Andes 



(201). 



363. North America presents the typical form and 

 configuration of a continent, but it resembles South America 

 passed through a mangle, being larger, wider, lower, with 

 less contrast between its heights and plains, and a much 

 more broken coast-line. Fig. 58, a section across the 

 continent on the parallel of 36 N., and Fig. 59, on the 



FIG. 58. Section across North America in 36 N. Vertical scale 

 300 times the horizontal. Sea-level marked O. 



meridian of 90 W. along the central low plain, are on 

 the same scale as that of South America. The total length 

 of the continent, nearly on the meridian of 100 W., is 



