DETAILED DESCRIPTION OF THE AREA. 163 



East of the anticline a thrust-fault is seen, and what lies east of 

 the latter consists of flysch and the eocene igneous rocks, no older 

 beds than Gieumal sandstone being exposed. The fault appears to 

 have been originally a narrow syncline which was subsequently con- 

 Verted into a thrust-fault with the result that parts of the lower limb of 

 the original syncline were cut out. 



The anticline is of a dome shaped character. At the base it is 

 denuded down to the middle Jurassic limestones, Spiti shales being 

 preserved in one small patch only. The eastern limb, however, includes 

 Spiti shales, Gieumal sandstone and part of the upper flysch. This 

 limb is generally of a simple structure, the dip being low, but in the 

 neighbourhood of the fault, the structure becomes complicated. I 

 have already described the flexure which suddenly sets in at Talla 

 Kiogarh If. E.G., and further east the beds, chiefly Gieumal sandstones 

 with remains of upper flysch, are laid into narrow zigzag folds until 

 the fault is reached. 



We have now to consider the structure of the area to the east of 

 the fault. 



Near Kiogarh Chirchun E.G. a magnificent section is exposed, 

 plainly showing an overfold made up of Gieumal sandstone, upper 

 flysch and the eocene volcanics (see pi. 4). 



Over-fold in Flysch. — The longer limb of the overfold is little dis- 

 turbed and represents from the Gieumal sandstone up to the sandstones 

 (45), a normal sequence of beds. Above the last mentioned sandstones 

 the tuffs (4/) should be found, but they must be wanting as they were 

 nowhere observed, a fact which, as will be shown below, must be ex- 

 plained by denudation having preceded the volcanic eruptions. In 

 the case of the overfold a small reversed fault is seen which traverses 

 the brown sandstones (4^), and the hard shales (qd). 



In the lower limb, which is partly encumbered by debris, the only 

 flysch divisions visible are the red shales (4a) and the sandstones (45). 

 This overfold borders to the west on -the great thrust-fault. Here 



{ 37 ) 



