l()t SUB-HIMALAYAN ROCKS OF N. W. INDIA. [CHAP. IV. 



intended to distinguish between the Sivaliks on the one hand and the 



Nahun and Subathu group on the^other. The map was published after 



his death. 



Cautley was, no doubt, correct in pointing to the Nahun region as the 



most likely ground in which to establish- the con- 

 Possible occurrence of . ;. A . 

 Nahun beds in Sivalik nection ot the Sivalik rocks with those to the 



north of the duns, not knowing that in identi- 

 fying the Nahun rocks with those at the outer base of the Sivalik hills 

 he had himself welded the first link of the chain. Whether or not this 

 idea be confirmed (I have already (page 15) given my reasons for doubt- 

 ing it), there can be no question that the rest of his section at Nahun 

 is erroneous ; the highly fossiliferous, conglomeritic, soft rocks about 

 Deoni and Jabri, in the valley of the Markunda, south of Nahun, are 

 unquestionably more recent than the Nahun rock, from the debris of 

 which they were principally formed, and against the denuded edge of 

 which they were deposited. So that, should the disputed identification 

 be ultimately established, it will involve the division of the section in 

 the Sivalik hills, and not the union of all these rocks with those at 

 Nahun. The supposition we shall then have to make regarding the 

 process of formation will be but a slight modification of that which must 

 be independently adopted, — a slow and partial upheaval of the Nahun 

 rocks along the edge of the area of deposition, involving their partial 

 denudation and erosion, and the deposition of the upper group in very 

 approximate parallelism of stratification, such as it might be difficult, if 

 not impossible, to detect, when the two became subsequently contorted 

 too-ether. I have given an imaginary section of such a state of things 

 in Fig. 11- Were the strata there represented to become contorted, it 



Fig. 11. 



Possible original relation of Nahun and Sivalik groups. 



