Effects of Mountain Masses. 119 



of Europe and Siberia, although a small' part, comparatively, of 

 the Siberian plain is good for corn. 



Asia. 



The regularit}^ in the motion of the currents of air and water 

 prevailing in the western hemisphere and the Atlantic ocean is 

 apparently lacking in Asia and the Indian ocean. The moun- 

 tains of America run northward and southward, and have little, 

 if any, effect in originating currents of air, and none at all on 

 the ocean currents. In Asia the largest and highest mass of 

 mountains in the world runs east and Avest, and from their foot- 

 hills the great plains of India and China extend to the Indian 

 ocean and the China sea, bringing a polar climate into close 

 contact with the torrid zone. 



Cold winter winds blow from the Himalayas and the high 

 plateaus of central Asia southwestward into Indian ocean and 

 China sea and drift the waters with them. When the sun turns 

 toward the north in the summer solstice and the plains in India 

 and China become heated by the torrid sun, the wind changes 

 and blows toward the northeast. At the meeting of the winds 

 the monsoon breaks, and the cyclones of India and the typhoons 

 of China follow. They are soon over, and then the monsoon 

 blows over Indian ocean and China sea. All India, Kashmir 

 and western Tibet, Farther India, Annam, and eastern China 

 and Japan are Avell watered, fifty feet of rain falling in a year in 

 some parts of India. 



In these countries there are generally six months of rainy 

 season and six months of dry. In parts of India the water of 

 the rainy season is stored in large reservoirs for irrigation in the 

 dry season, while in China numerous canals between the dif- 

 ferent rivers in like manner irrigate the land. India and China 

 are among the richest countries of the world and have the 

 densest population, though destined to be surpassed in the 

 future by the population of the Amazon and Mississippi valleys. 



We have thus seen the effects of the winds and ocean currents 

 in modifying the climate and in enriching the great valleys of 

 South America and North America, of Europe, India, China 

 and Jajjan. 



Deserts or Basins. 



About one-fifth of the territory in each continent is arid and 

 desert land. With one or two possible exceptions these arid 



