310 



GEOLOGICAL SURVEY 



North-Western Mysore have also yielded implements of that 

 type and in some cases in large numbers. 



The interesting points in connection with the alluvia in the 

 Madras country are the evidences of great changes of course 

 of both the Palar and Nagari rivers and the evidences of 

 changes in level of the coast alluvium, the last being by a 

 movement of elevation. Beds of subfossil marine shells of 

 living species at considerable distances inland in and near 

 Madras. 



This is shown by the existence of the chief economical 

 point of interest near Madras is the vast supply of extremely 

 pure clay to be found in the plant beds in the Sripermatur 

 area and also in the eastern part of the Alicoor area. 



The survey of this region was completed in 1864, but it was 

 not till 1873 that the full memoir on it was published. A 

 short sketch of the results had, however, appeared in the 

 Eecords in 1870. 



On the completion of the survey of the Kadapa and 

 Karnul rocks in 1869, the author was deputed to take up the 

 survey of the transition rocks in the South Mahratta country 

 and to make a traverse through Bellary District en route along 

 the line of railway so as to connect the new and old work. 

 These rocks occupy a zone between the southern boundary of 

 the overlying Deccan trap and the underlying gneissic rocks. 

 The zone having very ragged boundaries large tracts both 

 of the trap and gneiss countries had to be traversed in merely 

 mapping the boundary. The transition rocks were found to 

 belong to two series, as well as to occupy two quite distinct 

 basins; the rocks in the eastern basin, to which the name of the 

 Bhima 23 basin was given, corresponding very closely in petro- 



23 This name was chosen as the shortest and most suitable to designate the 

 series crossing the Bhima river. The eastern and larger half of this basin 

 was surveyed by Mr. King, whose views as to the age of the rocks agreed 

 with those formed by the author. 



