GEOLOGY. 31 



From a geological point of view the trip proved in many respects to be of considerable 

 interest, particularly as supplementing some former observations made more to the west. 

 Although there is not much variety in the rock formations, we may distinguish three successive 

 series. 



1. The most southern part of the province, along the foot of the hills, is formed of 

 alluvial gravels and sand, in whose unfathomable depths are swallowed both the Artysh and 

 Sogon rivers before they can reach the Kashghar Daria. 



tibi M,r,am. Kngitdr. 



i. Gravel. 23. Gravels and conglomerates in Artysh beds. 



3. Artysh beds. 3. Shales and limestone. J 



4. Carboniferous, crinoidal, dolomitic limestone. 



Section from the Kashghar plain to Tongitar, about 25 miles. 



2. The second series includes the low hills which extend diametrically from north to south 

 over about 30 miles, while the prevalent strike is from north-east by east to south-west bv 

 west. All these lower hills are occupied by Artysh beds, of which I spoke in a former com- 

 munication. 2 They are separated into two groups. The lower beds consist of greenish or 

 reddish clays or sandstones, and the upper of coarse conglomerates, which on a hill south 

 of Tongitar have a thickness of about 1,000 feet. At their contact both groups 

 generally alternate in several layers. An anticlinal runs almost through the middle of their 

 superficial extent. At the fort Ayok-sogon it is caused by a low ridge of old dolomitic lime- 

 stones on which the Artysh clays and sandstones found a firm support. To the south of it 

 the beds dip at angles of about 40 and 50 towards the Kashghar plain, in remarkably regular 

 and successive layers. North of the ridge, which has no doubt a considerable subterranean 

 extent in an east to west direction, all the beds dip towards north by west at a similar angle. 

 Approaching the higher range, more recent diluvial gravels cover most of the slopes. The 

 geological puzzle of finding strata of young beds as a rule dipping towards a higher range 

 composed of comparatively much older rocks seems to me to be due, at least in this special 

 case, to the phenomenon that the atmospheric waters which, descending on the crest, flow 

 down the slopes of the high ridge, gradually soften them, and if a subterranean outlet 

 facilitate it, the softened beds are worn away. While this process is going on, the more 

 distant beds simply subside in order to fill the vacant spaces. In some cases a sinking or 

 rising of the main range, or even an overturn of high and precipitous cliffs, seem to go hand 

 in hand with the action of erosion, but it is not always the case. I hope to illustrate this 

 idea by a few diagrams, partly derived from actual observations, on some future occasion. 



3. A third series of entirely different rocks forms the main range of hills, which are a 

 continuation of the Koktan range, and in which, more to the westward, are situated the 

 Terek and Chakmak forts. The average height of the range above the plain of Kashghar is here 

 between 1,200 and 1,300 feet, single peaks rising to about 1,500 feet. The whole of the southern 

 portion consists, as far as I could see, of carboniferous rocks, in which, however, there is a 

 great variety of structure. The lowest beds are very often a peculiar breccia-limestone passing 



1 In his field books Dr. Stoliczka speaks of these as probably triassic, but he may have changed his opinion subsequently, 

 for in his published uotes he classes them with the dolomitic limestone, and refers all to the carboniferous period. 

 - Ante, p. 24. 



