COUNTRY BETWEEN KOTAH DUN AND NEPAL. 107 



Gangolia gid (73) is a portion of the upper, limb of the same sigma- 

 flexure, though in a certain sense only, inasmuch asjthe conglomerates 

 there are of much higher horizon in the Siwalik stage than those in the 

 Sara N., and inasmuch as there is no sand-rock below them. Thus 

 the conglomerate of Gangolia gdd unconformably overlies the Nahans 

 with no intermediate sand-rock, which must have been denuded away 

 along what was a rising line of disturbance during an early phase of 

 the same sigmaflexural movements ; which movements continuing later, 

 when the conglomerates of Gangolia gcid were deposited, finally influ- 

 enced them also. 



Herein it may be remarked that the section is very similar to 

 that south of the Dhangari (19) and Sanguri (20) sots; and I woulfl 

 apply to both the same explanation regarding the absence of the lower- 

 most Siwalik conglomerate, and of the sand-rock below the conglo- 

 merate, on the uplift side of the fault. That explanation demands that 

 the line of the reversed fault be mentally represented, not as a sudden 

 break, but as a continuous line of weakness from early in the M. Siwalik 

 age up to late U. Siwalik times. Thus the sand-rock, and the lower 

 beds of the conglomerate, if thinly deposited north of the fault at inter- 

 mittent times, must, owing to the constant rising of that part, have ever 

 been suffering almost contemporaneous denudation ; whilst the beds 

 to the south were preserved by being forced below the reach of denuda- 

 tion. The Gangolia gad conglomerate, therefore, and that of Jirinj^la 

 (section V), are remnants which are on their way to obliteration. 

 Their temporary preservation, however, is a valuable index as to the 

 style of earth-movements along the lines of these reversed faults. 



But we have also another very important deduction to make 

 from this same conglomerate. We see that it overlaps, not only the 

 Nahans, but also the Himalayan traps to the north, and that it trun- 

 cates the main boundary fault in a most absolute and uncompromis- 

 ing manner ; thus shewing that the latter was altogether anterior to 

 the formation of those uppermost Siwalik conglomerates. Lastly, 

 the reversed fault bounding the Gangolia geld conglomerates on the 

 north must be the most recent of all these lines of weakness. 



( 165 ) 



