INTRODUCTORY. 7 



east monsoon than does Madura. Except along a narrow tract close in to 

 the foot of the ghats and in certain places opposite to deep gaps in the moun- 

 tain range, the south-west monsoon rains benefit neither district to any ap- 

 preciable extent, except it be by giving rise to the formation in some seasons 

 of severe local thunderstorms which are accompanied by very heavy rains. 



According to the rainfall map of India given by Dr. Brandis,^ the 

 eastern part of Tinnevelly District is very dry, having an annual average 

 of less than 30 inches ; but in the western part of the district the narrow 

 tract above referred which gets the benefit of the south-west monsoon rain, 

 enjoys a considerably moister climate with over 30 inches of annual rainfall. 



In Madura the dry part of the district lies in the centre (including 

 the Tirumangalam, Madura and Melur Taluqs) and has a moister tract 

 both on the west and the east ; the former being a continuation of the 

 moister zone along the foot of the mountains^ the latter a tract of country 

 running along the sea-board. 



In neither district are the north-east monsoon or winter raina abso- 

 lutely reliable, and if they fail, the most important dry crops and the 

 wet crops under the rain-fed tanks cannot be raised and much distress 

 ensues. The failure of the monsoon rains in one season is often followed 

 by excessive rains and consequent extensive and destructive floods. 



On the whole both districts are very badly clothed with wood. The 

 formerly extensive forests have been recklessly felled, and it will require 

 many years of very earnest conservancy to see the country properly 

 tree-clad once again. 



The rocks recognised during the progress of the survey may for con- 

 Schedule of geological venience of description be arranged as in the 

 formations. subjoined tabular statement :— 



8. Soils and subaerial deposits. 



7. Blown sands, red (teris) ; white (coast dunes). 



6. Fluviatile and marine alluvia, Kankar deposits. 



5. Sub-recent marine beds, limestones and grits. Upraised coal reefs. 



' On the distribution of forests in India, by Dietrich Brandis, Ph. D., Inspector-General 

 of Forests, Calcutta. Keprinted from the Transactions of the Scottish Arboricultural 

 Society, 1873. Edinburgh. M, Farlane and Erskine. 



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