86 MIDDLEMISS: PHYSICAL GEOLOGY OF SUB-HIMALAYA. 



and the Chokamb dun. There are no good exposures of the rock in 

 this very shut-in and winding stream. Such as there are merely 

 shew sand-rock the whole way, dipping at high angles (8o° and 90 ) 

 N.E. or N.N.E. A forest fire-line leading from Chokamb up to the 

 Deolbdri d£nda (46) shews a fairly contrasting junction between the 

 sand-rock and the third Nahan zone, indicating the presence of a 

 reversed fault ; but reliable dips cannot be obtained. The Nahans on 

 the ridge are dipping N.E. 40 . The southern boundary of the Ma'ndalti 

 sand-rock band is simply one of passage from the Nahans into the 

 former. The structure here, therefore, is merely a continuation of 

 what we have seen in the PeUni R. above Gutua g£dh. The third 

 Nahan zone to the north of this is also simply a continuation of the 

 same zone in the Peldni R. above Halduwdla ; whilst there is no 

 reason to doubt that the main boundary to the north of it is in any 

 way different to the same divisional line in the Pelani R. 



As we stand on the flat little chaor of Chokamb, where there is a 

 forest bungalow, we look west towards the Kho 



Westward extinction 



of these duns and longi- R. and observe that the low country which forms 



tudinal valleys. . ' 



the Sona N. and the Kotri dun on the one hand > 

 and the Mandalti R. and the Chokamb dun on the other hand, gives 

 way gradually, so that the east boundary of the Kho R. is a continuous 

 transverse ridge running N.E. and S.W. This expresses the fact 

 that the two sand-rock zones, which give rise to those longitudinal 

 valleys and duns, have come to an end. After describing the section 

 up the Kho R., we will consider this extinction of the sand-rock 

 zones in its physical bearings. 



Country between Kotdwar and the Mitawala 

 (Mithi) S6t. 



The Sub-Himalayan zone between these two places is of narrower 

 width than we have yet seen it to be. Having 



Orographical features. .,.,., , «.. " i«« 1 11 



left behind us the Siwalik conglomerate and the 

 sand-rock, the former of which practically dies out at the Ramganga, 



( H4 ) 



