CHOKAMB AND KOTRI DUNS, 85 



increases to 70 and 8o° where the Siwalik conglomerate, the continua- 

 tion of the thin band of the SonaN., is met with. It is very thin here, 

 a mere relic, and after turning over to 8o° W.S.W., there is a small 

 interval of unseen ground where it may be inverted, and then we 

 have the reversed fault separating it from the Nahans, which rise in 

 a steep scarp and display very markedly their characteristic basal 

 brownish and purple shales. The river-bed is now a gorge again, 

 cutting through the Nahan ridge. The dips are at first due east at 

 6o°, but this gradually changes to E.N.E. and then to N.E. at angles of 

 6o° and 50 . This ascending series across the middle band of Nahans 

 insensibly merges into the sand-rock at the junction with the Dimkeh 

 sot (43), at which place the dip is 55 N.N.E. So far then there is a 

 great resemblance between this section and the Ramganga-Pelini 

 section ; and the rest of the way to the main boundary across the 

 Chokamb dun is also very similar. 



The Chokamb dun, which we now enter, is essentially low coun- 

 try, but, like the Kotri dun, lacking- the real 



Chokamb dun. . 



characteristic of a true dun, namely, the Siwa- 

 lik conglomerate. It is entirely carved out of the sand-rock series, a 

 continuation and expansion of the second sand-rock band through 

 which the Manddlti R. runs. The expansion is due to the twisting 

 of the strike, whereby the southern boundary of the sand-rock is 

 thrown more towards the plains, following in an indirect and imper- 

 fect way the southward bulging of the middle Nahan zone in the direc- 

 tion of the Thakal gddh da*nda. The dip in the sand-rock of this 

 zone is N.N.E. along the Dimki and Debineh sots, first at angles of 

 50 and 40 , which increases to 90 at Debineh parao (44). It is not 

 clear whether there is an inversion, or not, towards the next Nahan 

 zone. If there be one, it must be slight ; for the great disparity between 

 the two rocks at their junction shews that the junction is far ftom 

 being normal and conformable. Up the Bhirgadi (45), where it joins 

 the Dimki, the dips are 40 and 30 E N.E. 



The Mandcilti R., which is parallel with the Sona N., and analogous 



Mandalti (Mundaltee) to Lt in eve, T aspect, takes its rise near 

 R - Chokamb in a low flat divide between its bed 



( '43 ) 



