Chap. I.] general description of area. 3 



second volume of the "Memoirs of the Geological Survey of India." In 

 the following seasons it was intended to carry on this work towards 

 Delhi, and through the country to the south and west of that city, 

 but in 1857 the mutiny broke out, and for two successive seasons it was 

 impossible to visit that part of the North- Western Provinces for the 

 peaceful purposes of field geology. The hills, however, were compara- 

 tively secure, and to them accordingly the attention of the Survey was 

 temporarily directed. The great series of tertiary strata, of which the 

 Subathu beds form the base and the Sivaliks the top, was chosen as the 

 special object of investigation, because these rocks had already excited so 

 much public interest ; and the excellent map of a large section of the 

 North- Western Himalayas, which had just been published by the Sur- 

 veyor General, offered rare facilities for pursuing successfully the geology 

 of this portion of the hills. 



In endeavouring to add to the valuable knowledge of the geological 

 relations of the Sub-Himalayan regions, with which palaeontologists have 

 supplied us, I have almost exclusively attended to the questions of 

 lithology and stratigraphy, because up till this time little or nothing had 

 been known of the nature of these relations, though some of the rocks 

 have been so well known from the fossils which they have yielded. 



The area included in the accompanying map, and to the description of 



which this memoir is more particularly devoted, is contained between 



the Ganges on the south-east and the Ravee on the north-west. The 



direct length of this tract of country is about 230 miles ; its width varies 



from twenty to sixty miles, the average being at least 



A vpfl described 



thirty ; so that the entire area is about 7,000 square 

 miles. Although equal in length to that of the base of the Pyrenees on 

 the French side, this area does not represent more than a sixth part of 

 the entire range of the Himalayas. In addition to the description of the 

 Sub-Himalayan zone, included in the accompanying map, I shall have 

 some observations to record upon the rocks that bound this great tertiary 



