202 GR1ESBACH : GEOLOGY OF THE CENTRAL HIMALAYAS. 



we have the first clear indication of the lower Silurians, which are 

 seen in full force on the top of the Tsang Chok La* (pass) itself. 



Near Mendi camping-ground the rock is lower 



Silurians near Mendi. ..... j j i • i_ i i a. 



3 silunan limestone, and dark greenish clay-slate, 



but I have no fossils out of it, with the exception of fragments of 



Corals. But the position immediately above the red-quartz shales (3) 



make its age apparent. Between Mendi and the top of the Tsang 



Chok La the prevailing rock is dirty pink quartzite, with greenish 



orev shales, the well-known upper silurian division. Enormous 



masses of debris cover up the last ascent to the pass, nothing of the 



rock in situ is seen there ; but the cliffs overhanging the saddle of 



f the pass itself are composed of white carbonifer- 



Carboniferous 01 r r 



Tsang Chok La. ous quartzite (8) . The descent of the pass to 



north-east into the Hop Gadh (see pi. 11) leads over an entire section 

 of palaeozoic rocks ; the Hop G4dh itself corresponds more or less 

 with a line of dislocations and the high cliffs which form the right side 

 of the Hop G£dh are formed of sections of the trias and rhaetic. 



The season was already too far advanced when I reached the top 

 of the Tsang Chok Ld in 1882 to do more than reconnoitre Hundes 

 from there ; the thermometer at Mendi during the day rarely rose 

 above 8° Fahr. in the shade, and of course all springs and streams 

 were frozen, so that I had to retrace my steps rapidly not to become 

 snowbound. I again visited the Nilang area the following year, and 

 ^ f Mo«o *n this time, instead of ascending the Jadh Ganga, I 



Cross from Naga to ' ° " ° » 



the Changanmu Gadh. branched off to east. From the Naga camp I 

 crossed the range to eastwards into the Changanmu Gatdh, a tribu- 

 tary of the M£na Gadh, by a pass which is over 19,000 feet above 

 the sea, and gradually ascending the Changanmu stream, crossed a 

 very high but easy pass into the upper Hop Gadh. It is a route 

 which, according to the natives of Nilang, used to be much frequented 

 by shepherds some thirty years ago, but is absolutely never traversed 

 now. Certainly it is a particularly difficult one, and the country for 

 many marches is absolutely a wilderness, and mostly covered with 

 snow. I found it much more instructive, however, than the regular 

 ( 202 ) 



