GEOLOGY. 15 



PART II. 



THE HILL RANGES BETWEEN THE INDUS VALLEY IN LADAK AND SHAH-I-DULA ON THE 



FRONTIER OP YARKAND TERRITORY. 



[This section is copied, with a few verbal alterations, from the Records of the Geological Survey of India, VI. VII, p. 12.] 



THE following brief notes on the general geological structure of the hill ranges alluded 

 to are based upon observations made on a tour from Leh, via Changchenmo, the high plains 

 of Lingzi-thung, Karatagh, Aktagh to Shah-i-dula, and upon corresponding observations 

 made by Dr. H. W. Bellew, accompanying His Excellency Mr. Forsyth's camp along the 

 Karakoram route to this place. 



Before proceeding with my account, I will only notice that our journey from Leh (or 

 Ladak) was undertaken during the second half of September and in October, and that we 

 found the greater portion of the country north of the Changchenmo valley covered with 

 snow the greatest obstacle a geologist can meet on his survey. While on our journey the 

 thermometer very rarely rose during the day above the freezing point, and hammer operations 

 were not easily carried out. At night the thermometer sank, as a rule, to zero, or even to 8 

 below zero, in our tents, and to 26 below zero in the open air. Adding to this the natural 

 difficulties of the ground we had to pass through, it was occasionally not an easy matter to 

 keep the health up to the required standard of working power. 



Near Leh, and for a few miles east and west of it, the Indus flows on the boundary 

 between crystalline rocks on the north and eocene rocks on the south. The latter consist 

 chiefly of grey and reddish sandstones and shales, and more or less coarse conglomerates, 

 containing an occasional N-ummulite and casts of Pelecypoda. These tertiary rocks extend 

 from eastward south of the Pankong lake, following the Indus either along one or both 

 banks of the river, as far west as Kargil, where they terminate with a kind of brackish and 

 fresh-water deposit, containing Melanice. 



Nearly the entire ridge north of the Indus, separating this river from the Shayok, and 

 continuing in a south-easterly direction to the mouth of the Hanle river (and crossing here 

 the Indus, extending to my knowledge as far as Demchok), consists of syenitic gneiss, an 

 extremely variable rock as regards its mineralogical composition. The typical rock is a 

 moderately fine-grained syenite, crossed by veins which are somewhat richer in hornblende, 

 while other portions contain a large quantity of schorl. Both about Leh and further 

 eastward extensive beds of dark, almost black, fine-grained syenite occur in the other rock. 

 The felspar often almost entirely disappears from this fine-grained variety, and quartz remains 

 very sparingly disseminated, so that gradually the rock passes into a hornblendic schist ; and 

 when schorl replaces hornblende, the same rock changes into layers which are almost entirely 

 composed of needles of schorl. Again, the syenite loses in places all its hornblende, the 

 crystals of felspar increase in size, biotite (or sometimes chlorite) becomes more or less abund- 

 ant, and with the addition of quartz we have before us a typical gneiss (or protogine gneiss), 

 without being able to draw a boundary between it and typical syenite. However, the gneissic 

 portions, many of which appear to be regularly bedded, are decidedly subordinate to the 



