GENERAL FEATURES OF THE EARTH. 25 



the Mackenzie, to the northward ; the central area of the plain 

 dividing the three systems being only about 1700 feet above the 

 ocean, — a less elevation than about the head-waters of the Ohio in 

 the State of New York. 



South America, like North America, has its great western range 

 of mountains, and its smaller eastern (fig. 19 ) ; and the Brazilian 



Fig. 19. 



A A 



W a 7; £ 



line (b) is closely parallel to that of the Appalachians. As the 

 Andes (a) face the South Pacific, a wider and probably much 

 deeper ocean than the North Pacific, so they are more than twice 

 the height of the Rocky Mountains, and, moreover, they rise more 

 abruptly from the ocean, with narrow shore-plains. 



Unlike North America, South America has a broad ocean on the 

 north, — the North Atlantic in its longest diameter ; and, accord- 

 ingly, this northern coast has its mountain-chain reaching along 

 through Venezuela and Guiana. 



The drainage of South America, as observed by Professor Gruyot, 

 is closely parallel with that of North America. There are, first, a 

 southern, — the La Plata, — reaching the Atlantic towards the south, 

 between the converging east-and-west chains, like the Mississippi ; 

 second, an eastern system, — that of the Amazon, — corresponding to 

 the St. Lawrence, reaching the same ocean just north of the 

 eastern mountain-border ; and, third, a northern system, — that of the 

 Orinoco, — draining the slopes or mountains north of the Amazon 

 system. The two Americas are thus singularly alike in system of 

 structure : they are built on one model. 



The relation of the oceans to the mountain-borders is so exact 

 that the rule-of-three form of statement cannot be far from the 

 truth. As the size of the Appalachians to the size of the Atlantic, so is the 

 size of the Rocky chain to the size of the Pacific. Also, As the height of the 

 Rocky chain to the extent of the North Pacific, so are the height and boldness 

 of the Andes to the extent of the South Pacific. 



30. (2.) Europe and Asia. — The land covered by Europe and 

 Asia is a single area or continent, only partially double in its 

 nature (§ 19). Unlike either of the Americas, it lies east-and- 

 west, with an extensive ocean facing Asia on the south ; and its 

 great feature-lines are in a large degree east-and-west. The Arctic 

 is on the north ; the North Atlantic is on the west ; the North 



