4 FOOTE : GEOLOGY OF MADUIlxi AND TINNEVELLY DISTRICTS. 



of the very heavy rainfall is drained off into the sea or the back- 

 waters of Cochin and Travancore, and forms 



Position of watershed. i • i 



powerful streams rushmg throngn a wide tract 

 of densely- wooded hill country, while on the east side of the mountains 

 the rainfall is very scanty, and the rivers receive only occasional freshes 

 which cannot be steadily depended on. 



Thus the Vaigai, the principal river in Madura district, though it 

 water-supply of the "ses in a valley surrounded by high mountains 

 ^*''^'^^- covered in great part with dense forests, receives 



a very scanty and uncertain south-west monsoon supply, from the fact 

 that the monsoon clouds do not proceed eastward beyond the watershed 

 which coincides with the western and southern sides of the Kambam valley. 

 The Varshanad spur and the lofty Peya Malai or Pemalai^ at its 

 southern end, though attaining an elevation of from 4,000 to 5,570 

 feet, are rainless as compared to the mountains a few miles only to 

 the south-west. Further to the north the Palani mountains, though as 

 nearly as possible equal in their average height to the more westerly 

 mass of the Aiiai Malai (elephant mountains), receive a greatly smaller 

 water-supply from the south-west monsoon. The chief rainfall in the 

 Madura and Tinnevelly plains occurs during the north-east monsoon, 

 and when this fails partially, as it not unfrequently does, the plains 

 suffer from severe drought. The Tambraparni river has from time im- 

 memorial never failed in its water-supply, and two enormous crops of 

 rice are raised every year in its most fertile valley. The Vaigai, 

 though a considerably larger river, reckoning size by the area of drainage, 

 can only ensure one crop per annum, the second crop frequently failing. 

 This untoward state of things would appear to be perfectly reme- 

 diable by a great engineering work known in 

 The Peria-ar project. t-^t ii -r.-_ ' , ^ ^ • i 



Madras as the reria-ar project by which the 



' The Pemalai, or devil mountain, as it is popnl.irly called, should, according to Bishop 

 Ciildwell, the great Dravidian scholar, be rightly called I'eyamalai, or the raiitless mountain, 

 a very suitable name, as it is often visible under a clear sky when PuUivuraugan peak and 

 the main mass of the mountains arc completely hidden by the dense clouds of the south-west 

 monsoon and deluged witli rain. 



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