PART 4 .] 
McMahon : The Simla Himalayas, 
221 
If this view be correct, may we not suppose that the thickness of the Chor gneiss is 
not as great as it seems to be, but that it is, probably, simply an anticlinal in the gneiss, now 
masked, by the metamorphism which has obliterated all traces of bedding. 
In conclusion, I would venture to express the opinion that the metamorphism of the 
“ central ” gneiss is due to plutouic heat. The manner in which, as before described, the 
direction of the axes of felspar crystals changes, as the metamorphism increases, appears 
to me to indicate a freedom of motion which the constituent minerals could hardly have 
possessed unless the rock had been heated to a point approaching fusion. In the Satlej valley 
the signs of granitic intrusion into the central gneiss region are abundant, and they are not, 
I think, altogether wanting in the Chor. In the bed of the stream below Obaita (on the 
southern flank of the Chor), there is a huge block of the gneiss 67'X 62'X 37'. It is 
penetrated by granite veins which run at various angles ; the principal one, about 4 feet wide, 
has caught up a fragment of the porphyritie granitoid gneiss in its passage, and this shows 
in the middle of the vein. This surely is an intrusive vein and not one due to segregation. 
The presence of granite veins in the central gneiss of the Satlej valley and of the Chor 
seems to me to indicate that the central gneiss was at one time well within the action of 
the more deep-seated plutonic forces, and that its metamorphism is duo to plutonic heat. If 
so, the Krol, the Infra-Krol, and the Blaini rocks cannot be older than the gneiss, and cannot 
really underlie it, whatever the appearances at certain points may be. 
VIII.—Chin i to Jangi. 
My paper has already extended to such length that I must he brief in my remaining 
observations. Following the right hank of the Satlej, from Cbagaon past Chilli, the rocks all 
the way to Pangi are “ central ” gneiss alternating with schists of the mica-schist series. Near 
Cbagaon there is a broad dyke of granite, and the signs of granitic eruption now become 
numerous. At Pangi the “central” gneiss is much twisted about by the rising granite, which 
high up in the cliffs overhanging Pangi is seen bursting through thin-bedded mica-schists. 
The mica-schists are much darkened by the passage of the granite. 
Between Pangi and Earaug there is profuse granitic intrusion, and the rocks are riddled 
with granite veins in all direction. Beyond Pangi there is a broad dyke of whitish granite, 
and as it is neared the felspar in the gneiss is scattered about in its matrix in a most remark¬ 
able way. About f of a mile on the Pangi side of Rarang, a dyke, 300 or 400 feet wide, cuts 
clean through the thin-bedded mica-schists up to the crest of the mountain, sending out 
large lateral dykes into the schists. 
A little beyond Rarang the great eruption has taken place, and it extends from this 
point all the way to Jangi (8 miles by road—see the Trigonometrical Survey Sheet No. 65). 
The schists cling, hero and there, to the face of the granite, aud form subordinate spurs, 
round which the road at times winds; hut the whole core ol the mountain, extending from 
Rarang on the south-west sides of the Gongra peaks to Jangi on the north-east side of those 
peaks, is all granite. How far it extends in a north-westerly direction along the Gongra 
range I cannot say, but it evidently does not extend beyond Jangi along the Lipe road, as 
the natives told me the rocks in that direction were all kaicha (friable). 
I was not able to examine the left bank of the Satlej opposite Rarang, which I longed to 
do, but as far as I could judge by the eye, the granitic eruptions seemed to extend to the 
south, and I should not he surprised if the lofty Kaldang peaks, which rise to the height of 
21,250 feet and tower over the traveller within 6 miles of the road, were formed m whole, 
or in part, of this eruptive granite. That the great mass of granite between Rarang and 
Jangi is a truly eruptive rock I do not doubt. Between Rarang and Jangi I found numerous 
