THE JURASSIC SYSTEM. 
39 
6. The hills between Gyantse and the Karo La appear to be 
composed entirely of Jurassic rocks, chiefly dark 
Gorchl and Salagang. 
shale with some limestone, striking E.-W. and 
dipping mainly to the north. The shales are often concretionary and 
comparatively little affected by the regional metamorphism so conspi- 
cuous in the neighbourhood of Gyantse, and even the occasional 
intrusive masses of diabase show no far-reachinij contact effects, the 
zones of alteration being confined to the immediate neighbourhood 
of the igneous rock. It is quite probable therefore that, under condi- 
tions more favourable to geological work, several fossiiiferous locali- 
ties might be found among fhe hills between the Ralung Chu and 
the Yung La. 
In the valley of the Ralung Chu fossils occur in the shales 
between the villages oi Gupshi and Lungma.* They are especially 
numerous at Gorchi where large numbers of belemnites were collected 
from a band of soft shales. A few miles higher up the valley belemnites 
and brachiopods {Rhynchontlla sp.) were found in the shale at' 
Salagang, and it is probable that the hills on either side of the Nyiru 
Chu between Gupshi and Khangma would also prove fossiiiferous 
for the rocks here appear to be less altered than their more westerly 
representatives in the upper reaches of the Nyang Chu. 
( f ) Between Karo La and Nam Tso. 
In the neighbourhood of the Karo La metamorphism is again 
prevalent and the rocks at the mouth of the gorge leading up to the 
pass are schistose limestones (calc-schistsj overlain by slates, which 
latter form the snowy peak of Nojinkangsang — the most conspi- 
cuous land-mark between Bhutan and Lhasa — and the greater part of 
the neighbouring ranges. The metamorphic character of these rocks 
is due chiefly to the presence of intrusive granite, which occurs in 
the hills to the north of Nojinkangsang, and which, though not 
seen in situ, is represented by numerous boulders in the valleys to. 
the east of the Karo La. 
' Not to be confused with the grazing-ground of the same name near Kampa 
dzong. 
( »6o ) 
