PETROLOGY. 23 



common. 



do. 

 rare, 

 do. 



common, 

 common locally. 

 do. 



! Purple and greenish gritty quartzites 

 Fine conglomerates . . 



Lydian stone .... 

 Decomposed greenstone . 

 Vein quartz .... 

 Well-preserved trap . . . 

 Ditto granite 



r Soft, brown and pepper-and-salt sandstone (Nahan) . common locally. 

 Older Tertiary . \ Greenish-grey shales ...... rather common. 



^ Ochre and dark brown shales .... do. 



The above gives a fairly accurate general idea of the composition 

 of the pebbles. This is all that is necessary here; for to detail the 

 composition of every pebble would be to describe prematurely the 

 petrology of the whole of the higher Himalayan range. 



A very constant character of the conglomerate is the alternations 

 of coarse and fine bands, and of sandy, loamy and clay beds with it. 

 Only in the Kotah dun, and at a few places near Durgapipal, where 

 outliers on the Himalayan rocks occur, is there any rapid, radical 

 change in the nature of the conglomerate. It is there seen to be 

 very angular, and composed of the particular rocks immediately in 

 the vicinity. There is some doubt, however, as to whether all these 

 should be classed with the Siwaliks, or with the superficial Recent 

 accumulations. More probably they represent those intermediate 

 strata which, as already indicated, blend, though in an imperfect way, 

 the Siwalik with the Recent period. 



As a whole, the Siwalik conglomerate may be said to be more 

 ferruginous, and to be composed of larger and coarser material in its 

 upper part, than at lower horizons. In the lower beds, the sandy- 

 clay partings become more frequent, and the material of the conglo- 

 merate finer, though different-sized pebble-beds alternate as before. 

 In numberless sections there is seen to be a petrological passage 

 from the conglomerate down into the stage next to be described. 

 I think this passage to be a real one, indicative of a gradual though 

 decided change of conditions at the time of its deposition ; but, as 

 other observers in the country further north-west have found local un- 

 conformabilities in it, I shall have to refer to the subject again later 



( 81 ) 



