198 



GR1ESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



Nilang. Granite. 



the Nanda Devi, and which I have separated for the present from the 

 rest of the metamorphics as the vaikrita system. How far this may 

 be the case must be left to future researches. I found the region 

 north-west of Nilang inaccessible with the means I had at my com- 

 mand, and had to content myself with including these semi-metamor- 

 phic beds in the haimantas which play a great role in the Nilang 

 area. The boundary of these rocks with the granite as drawn west 

 of Nilang is purely diagramatic ; not anywhere is the boundary well 

 defined, — in fact the granite seems to pass through a gneissic stage 

 into the felsites and quartzites of the vaikritas or haimantas of that 

 area. 



Arrived at Nilang, I observed the following : the valley widens 



there and several smaller side ravines, filled 

 with glaciers, send down large accumulations of 

 moraine matter which spread themselves into the Nilang valley 

 itself. There part of these clays and boulders have been re-deposited, 

 and form a fairly extensive undulating patch of land, which is culti- 

 vated by the Nilang people. Granite forms the surrounding hills of 

 the Nilang valley itself, but the semi-crystalline slates of the vaikritas 

 and haimantas are seen to form the upper part of the hill range which 

 extends on the right side of the Jadh Ganga to near the village of 

 Nilang. The beds of this formation dip to north-east, though much 

 disturbed, and the contact of the granite with the former is distinctly 

 that of an intrusive rock. Veins and dykes of granite penetrate the 

 slates in all directions near the contact, which is well seen just west of 

 the village of Nilang The slates are evidently much changed near 

 the contact with the granite ; in parts quite crystalline, and generally 

 showing a bright red belt of some fifty feet or more near the bound- 

 ary. 



The same granite is found in situ some distance up the valley; it 

 constitutes the lower part of the ranges which form the narrow valley 

 of the Mana Gddh, as far as about two miles east of Naga encamp- 

 in<r-oround, near the junction of the Jidhang with the Jddh Ganga. 

 I also found it some two miles north of Naga and close to Jadliang 

 ( 198 ) 



