CLIMATE. 119 



evidence of marine action has been found, so that subsequent 

 deposits must have been formed in fresh water. The Sivaliks 

 running along the foot of the Himalayas are river deposits of 

 sandstone, clay and conglomerates ; similar formations of the 

 same age occur in Assam and in Burma. The alluvial deposits in 

 the plains of the Indus, Ganges and Brahmaputra are of recent 

 origin ; no boulders or pebbles are found in them. They consist 

 chiefly of sandy, micaceous and calcareous clays. The older 

 alluvium is distinguished by the nodular segregations of carbonate 

 of lime known as " kankar." 



It will be easily understood that the nature of the soil differs 

 enormously. Those of alluvial origin are the most extensive, 

 and their consistence ranges from loose drift sands to stiff clays. 

 On the Deccan trap formation the soils are thin and poor on the 

 higher levels, but the well known fertile black cotton soil pre- 

 dominates in the low lands. On the rest of the peninsular area 

 the soils are derived chiefly from crystalline rocks ; they vary 

 very much in appearance, depth and fertility. 



3. Climate. 

 Owing to the great extent of the country and the varying condi- 

 tions prevailing in the several parts, it is not possible to speak of 

 the climate of India ; there are quite a series of climates, but they 

 may be arranged into the following four main groups or types : — 



(1) The climate of Tropical India. 



(2) ,, ,, North-western India. 



(3) ,, „ North-eastern India. 



(4) ,, „ The Himalayas. 



About one-half of the area of India, comprising the greater part 

 of the Peninsula and Burma, is situated south of the tropic. 

 These are the hottest parts of India as far as the average of the 

 whole year is concerned ; but the highest temperature is found 

 further north. The arrival of the south-west monsoon mitigates 

 the summer temperature in tropical India ; on the other hand, 

 this region enjoys little or no cool season, except at high elevation. 

 The second type of climate is found to the north of the tropic 

 in the dry, and in some cases almost rainless, plain of the north- 

 western part of India, comprising the area which is traversed by 

 the river Indus and its feeders. Here the highest summer 



