FORM AND STRUCTURE OF THE EARTH. 177 



Range of California are the most notable (Fig. 90, a). 

 South America has the Andes on one coast, the Brazilian 

 mountains on the other, and the great interior basin 

 drained by the Amazon, La Plata, and Orinoco Rivers 

 (Fig. 90, ). Similarly) the great basin of Africa is- 

 drained by the Mle, Niger, Congo, and Zambesi Rivers. 



Basin. Plateau. 



Plains. 



East and west section of North American Continent : cr, coast range ; SJ, San Joa- 

 quin plain ; S, Sierra ; w, Wahsatch ; c, Colorado range ; Ap, Appalachian. 



Andes. Brazil 



East and west section across South America. 



East and west section across Australia. 

 FIG. 90. Sections across North and South America and Australia. 



Australia is also a fine example, as shown in Fig. 90, c. 

 Europe and Asia have similar structure, but less perfect. 

 This continent is elongated east and west, and therefore 

 the section must be north and south. 



2. The Greater Range faces the Greater Ocean. 

 In America, the North American Cordilleras and the 

 Andes face the Pacific, while the Appalachian and the 

 Brazilian mountains face the Atlantic. In Africa and 

 Australia, on the contrary, the east range faces the 

 greater ocean, and is the greater. 



3. The greater chains are usually the most complex and 

 crumpled in structure, and give evidence of greatest vol- 

 canic activity in the present or in the past. 



LE CONTE, GEOL. 12 



