20 MIDDLEMISS: PHYSICAL GEOLOGY OF SUB-HIMALAYA. 



is a certain sequence in these Upper Tertiary strata, never departed 



from, without a fault, or thrust-plane, being evident. But the several 



members of the sequence, though of minor interest in themselves, 



become absorbing when regarded as the parts of a puzzle; which, if 



put together rightly, will initiate us in the mysterious workings of 



those elevatory powers, whereby band after band of rocks have been 



won from the oblivion of the plains and added to the achievements 



of the Himalaya; or they may be looked upon as an alphabet, or key, 



that will enable us to read this last volume of geological history, 



which, written in a strange language, now lies open before us. 



The superficial deposits of Recent age may be disposed of in a 



word or two. They consist of banks of coarse 

 Recent formations. , 



gravel and torrent-boulders, generally mixed 



with ferruginous sand or clay, which line the margins of many of the 



larger streams and rivers, and cover great portions of the duns and 



level chaors. In one or two localities about Chuna KMn and Madan 



Bhil, and in the more eastern portions of the Kotah dun, where the 



streams carry much lime in solution, there are some beds of very pure 



calcareous tufa, interstratified with gravel banks and sandy clays. 



The streams which emerge from the Kotah dun, at its eastern limit, cut 



through escarpments of the Siwalik conglomerate, often by a series 



of falls, or steps of calcareous tufa, one of which at Madan Bhil is 



about 50 feet high. The stream-beds are sometimes filled with huge 



weathered blocks of this tufa, of pale grey or dirty-white colour, and 



of an appearance akin to that of scoriaceous lava. Impressions of 



land-shells and plants are frequently found in them. In the Nehil 



Nadi, 1 south of Nairn Ta*l, there are also superficial deposits of gypsum 2 



of considerable extent. Re-made beds of the Nahan shales, sloping 



down the sides of the gorge a little south of the old Nehdlpur bridge 



(now gone), contain three or four beds of gypsum in irregular lumpy 



1 Nadi = small stream, in size between a river and a mountain-torrent. In future 

 " Nadi " will be written " N." 



2 Briefly mentioned in the Manual of the Geology of India, Part III, p. 454. See 

 also a paper by myself (Records G. S. I, Vol. XXII, p. 137) in which I estimate the avail- 

 able amount at 37,400 tens. 



( 78 ) 



