MEMOIRS 



GEOLOGICAL SURVEY OF INDIA. 



0)1 the Geological Structure of jjortions of the districts of Trichinopoly, 

 Salem, and South Arcot, Madras, included in sheet No. 1^ of the 

 Indian Atlas, by William King, Junr., and Robert Bruce Foote, 

 EsQRS., Geological Surveij of India, 



Chapter I. — General Sketch of Area, &,'c. . 



The country referred to in the following pages may be described 



as a great rectangular area, bounded on the 

 Area reported on. 



east by the Bay of Bengal ; on the west by 



an imaginary line coinciding with the longitude 78° 8' east of 

 Greenwich ; on the north and south by lines coinciding respect- 

 ively with 1"2° 10' and 10' 40' north latitude. This tract of coun- 

 try, which is included in sheet 79 of the Indian Atlas, has an area 

 of about 11,500 square miles, and, as might be expected, offers very con- 

 siderable diversity of aspect and structure. 



Physically, we must distinguish two great divisions of this area : — ■ 

 1st. — The flat region occupying the eastern and southern parts 

 of the rectangle; and 2ndly, the hilly region eml)racing the north- 

 western portion. The former is part of what is known as the Payen 

 Ghat, the true low country of the Carnatic; the latter forms geo- 

 graphically a great outlier of the Coromandel, or Eastern, Ghats, 



( 2^3 ) 



