GEOLOGICAL SURVEY OF INDIA. 241 



reliable group of these at Manegaon gave, below the depth of 

 60 feet (throughout which a constant temperature of 81° prevails) 

 a very steady rate of increase of 1° Fahrenheit for every 66 feet 

 in depth. 



Mr. Wynne was fully occupied in mapping the structural features 

 of the tertiary basin between the Salt Range and the mountains 

 to the north, which is often spoken of as the Potwar or Rawalpindi 

 plateau. It is on the whole a broad synclinal with many sub- 

 ordinate axes of flexure, and the disturbed character of the deposits 

 mates their study a matter of great difficulty. The post tertiary 

 deposits here are of much interest. They are found resting upon 

 tilted Siwalik strata at very high levels over the actual river courses, 

 so that prodigious denudation must have taken place since they 

 were laid down. There is much evidence to suggest that glacial 

 action took a direct part in the accumulation of some of these 

 deposits. 



During the working season of 1876-77 Mr. Blanford and 

 Mr. Fedden completed the mapping of Sind west of the Indus. 

 The former re-examined the Khirthar range from its northern 

 termination west of Jacobabad to the neighbourhood of Sehwan ; 

 he then re-mapped the cretaceous rocks in the Laki range south 

 of Sehwan, and after completing the geological lines in the Habb 

 valley, and marching westward along the coast as far as Sonmiani, 

 returned to Calcutta. Mr. Fedden, starting from Karachi, mapped 

 the large tract of country west of the Laki range from the neigh- 

 bourhood of Sehwan to the sea, an area of nearly 5,000 square 

 miles. Large additions were also made to the fossil collections 

 previously obtained. So much of the geology of Sind had been 

 determined in the two previous seasons that no very important 

 addition could be expected. It was, however, clearly ascertained 

 that a band of contemporaneous volcanic rock, from 40 to 90 feet 

 thick, intervenes between the base of the Ranikot group (lower 

 eocene) and the cretaceous beds, and there can be little doubt that 

 this thin lava-flow represents the great mass of the Deccan traps. 



Mr. W. T. Blanford's memoir (Vol. XVIL, Art. 1) on the 

 geology of "Western Sind* deals with that portion of the province 



* The names of the province of Sind and of the river called the Indus by Europeans 

 are really identical, and Hindu, Hindustan, and India are all derived from the same 

 source, the letters S. and H. being interchangeable. The old name of the Indus is 

 SindUn. There is a Muhammadan story about the name of Sind being derived from 

 Sindh, the brother of Hindh and son of Noah, 

 i Y 20321. Q 



