TILLA RIDGE. 125 



Round the termination of the ridge to the eastward is the low 



.„ . , , country and alluvium of the Jhelum, which, follow- 



Alluvium and couglo- '' 



nieratic zone. ing; the course of that river, extends along the 



southern side of the ridge past the wide sandy bed of the Bunh^r river, 

 as far as the neighbourhood of Dharapur. Embracing the low extremity 

 of the ridge, and rising from this alluvium, is a crescent-shaped belt of 

 low pebble-covered hills, derived from the waste of the incoherent 

 Upper Siwalik conglomerate rocks. The pebbles in these consist prin- 

 cipally of quartzose grit with fragments of other metamorphic or crys- 

 talline rocks, and the detritus, apparently of these beds, is found as a 

 re-arranged, unconformable, post-tertiary deposit, resting upon the flanks 

 of the ridge near Rotas. Where such beds as these occur in open ground, 

 it is very difficult to see their relations ; they weather down into beach- 

 like slopes, covering everything else from view, and when occasional cliff 

 or bank sections occur and total discordance can be seen, the re-arranged 

 materials simulate the original structure of the beds so closely that 

 appearances cannot always be trusted.^ The horse-shoe arrangement 

 of the pebbly ground, however, coincides with an anticlinal structure 

 seen at Rot^s gorge in the tertiary sandstones, &e., and conglomerate 

 bands are occasionally found intercalated with the latter beds in the 

 neighbourhood. 



The gorge of the Kahan river, near the old fortress of Rotas, shows 



„ , both these and the unconformable post-tertiary 



Rotas gorge. _ 



conglomerates, as well as the subjacent tertiary 



sandstone and clay beds (see fig. 11, PI. XII). The conglomerates 



are much more frequent over the country beyond the north-east 



bank of the river; while on the opposite side of the stream they 



* Upper Siwalik conglomerates and their debris, formed more largely or exclusively of 

 rounded syenite, quartzite, and other crystalline fragments, are widely distributed along the 

 Indus, beyond which river, on the track from Kalabagh to Shakardara, they are seen to be 

 perfectly conformable to the upper grey tertiary sandstones, &c., — single pebbles and layers 

 of pebbles first appearing, afterwards becoming more numerous, till at last enormous masses 

 of conglomerate supervene. 



( 125 ) 



