MEMOIRS 



OF THE 



GEOLOGICAL SURVEY OF INDIA. 



The Gneiss and Transition Rocks, and other Formations of the 

 Nellore portion of the Carnatic, by William King, B.A., 

 Deputy Superintendent {Madras), Geological Survey of India. 



PART I. 



CHAPTER I.— GENERAL DESCRIPTION. 



The selection of a fitting title for this memoir has been beset with 



much difficulty, for the country, the geology of which is about to be 



described, is not defined by any political or natural boundaries, except on 



two sides, while it includes portions of three districts in the Madras 



Presidency ; neither is there any special formation or series typically 



displayed in the area, sufficiently so at least to be thoroughly worthy of 



separate treatment. Still, as the most prevalent 

 Introductory. 



and conspicuous rocks are of the crystalline series, 



and the relations between this and the transition series are more fre- 

 quently displayed within this part of the Nellore District than in any 

 other portion of the Carnatic, these formations are selected as the more 

 particular theme of this work. The modus operandi of the Geological 

 Survey is likewise largely accountable for the presentation of such an 

 undefined area, for at the time when it was examined, the grouping of 

 the various rock systems of India was still in abeyance, and the areas for 

 survey were chosen partly according to the sheets of the Indian Atlas. 

 It is in this way that other portions of the Carnatic have been already 



( 109 ) 

 Memoirs of the Geological Survey of India, Vol, XVI, Art. 2. 



