INTRODUCTION. 121 



Shevaroys, the Nilgiris, the Palnisand the great ridge of high ground 

 forming part of the Western Ghats, stretching southwards as far as 

 Cape Comorin and reappearing above the sea-level in Ceylon. 



In the following year Mr. F. G. Brook-Fox, F.G.S., called my 

 attention to the occurrence of the same rocks in the South Arcot 

 district, and during the succeeding field season Dr, H. Warth made a 

 representative collection of the principal types exposed in that 

 area. 



At about the same time Mr. C. S. Middlemiss commenced survey 

 work in the districts of Salem and Coimbatore, and with the 

 assistance of Mr. F. H. Smith has since added several new localities 

 to those previously known. 



In the summer of 1897 I was able to devote a month towards 

 the examination of some of the interesting features presented by this 

 group in the immediate neighbourhood of Salem, whilst the following 

 field season was devoted to a systematic survey of the little province 

 of Coorg on the Western Ghats, where, with the help of Dr- 

 T. L. Walker, some very interesting facts, bearing especially on the 

 geological relations of these rocks to the older gneisses, were dis- 

 covered. 



All the observations above referred to were made after the real 

 nature of the rocks had been discovered by microscopic examination, 

 and although the petrological features of the same areas have fre- 

 quently been referred to in papers on related subjects published since 

 1892, no systematic description of the group has hitherto been put on 

 record. 



Messrs. F, H. Smith and T. L. Walker have recently found the 

 charnockite series developed over large areas in the districts of 

 Ganjam and Vizagapatam. 



B2 ( 3 ) 



