GEOLOGY. 21 



PART III. 

 FROM SnAH-i-DULA TO YARKAND AND KASHGHAR. 



[ From Records of the Geological Survey of India, Vol. VII, p. 49 ; and Qnart. Jonr. Geol. Soo., 1874, Vol. XXX, p. 571. ] 



IN a former communication I had already occasion to notice, that the rocks composing 

 the Kuenluen range near Shah-i-dula chiefly consist of syenitic gneiss, often interbedded, and 

 alternating with various metamorphic and quartzose schists. Similar rocks continue the 

 whole way down the Karakash river for about 24 miles. After this the road follows, 

 in a somewhat north-westerly direction, a small stream leading to the Sanju (or Grim) pass. 

 Here the rocks are chiefly true mica schist, in places full of garnets. Near the summit, and 

 on the pass itself, chloritic and quartzose schists prevail, in which veins of pale-green jade 

 occur, numerous blocks containing this mineral having been observed near the top of the pass. 

 All the strata are very highly inclined, often vertical, the slopes of the hills, and in fact of 

 the entire range, being on that account rather precipitous, and the crests of the ridges them- 

 selves very narrow. 



Sanja pan. 



la 



I. Metamorphic rocks. la. Submetamorphic schists. 9. Slates. 3. Sandstones and conglomerates. 



Section from the Sanju Pass to Kiwdz. 



To the north of the Sanju pass we again meet with metamorphic, mostly chloritic schists, 

 until we approach the camping place Tarn, where distinctly bedded sedimentary rocks cap 

 the hills of both sides of the valley. They are dark, almost black, silky slates, resting 

 unconformably on the schists, and are overlain by a grey, partly quartzitic sandstone, passing 

 into conglomerate. The last rock contains particles of the black slates, and is, therefore, 

 clearly of younger age. Some of the conglomeratic beds have a remarkably recent aspect, 

 but others are almost metamorphic. In none of the groups, the slates or sandstones or 

 conglomerates, have any fossils been observed ; but they appear to belong to some palaeozoic 

 formation. They all dip at from 40 to 50 towards north-east, extending for about 1^ 

 miles down the Sanju valley. Here they are suddenly cut off by metamorphic schists, 

 but the exact place of contact on the slopes of the hills is entirely concealed by debris. The 

 schists are only in one or two places interrupted by massive beds of a beautiful porphyritic 

 gneiss, containing splendid crystals of orthoclase and biotite ; they continue for about 18 

 miles to the camp Kiwaz. On the road, which often passes through very narrow portions 

 of the valley, we frequently met with old river deposits, consisting of beds of gravel and very 

 fine clay, which is easily carried off by only a moderate breeze, and fills the atmosphere with 

 clouds of dust. These old river deposits reach in many places up to about 150 feet 



