28 SECOND YARKAND MISSION. 



which appear to have taken place at the close of the caenozoic epoch within the southern 

 offshoots of the Thian Shan which we visited. 



Short as our sojourn in the mountains was, it proved to be very interesting and equally 

 instructive. Humholdt's account of the volcanicity of the Thian Shan, chiefly taken from 

 Chinese sources, receives great support ; but we must not speculate further beyond confid- 

 ing in the expectation that both meso- and csenozoic rocks will be found amply represented 

 in it. 



As far as our present researches on the physical aspect of the country extend, we may 

 speak of three geologically different ranges : the Terek range, which is the northernmost, the 

 Koktan in the middle, followed by the Artysh range, below which begins the Kashghar plain. 

 All three decrease in the same order in their absolute height, the last very much more so than 

 the middle one. The first consists of old sedimentary rocks, the second of similar rocks in 

 its southern parts, while younger tertiary and basaltic rocks occupy the northern portions ; 

 the third is entirely composed of young tertiary deposits. The general direction of all 

 the ranges is from west to east, or nearly so : this direction evidently dating from the 

 time when the whole of the Thian Shan chain was elevated. The undulating high plateau 

 between the Terek and the Koktan is, near Turgat-bela, about 8 miles wide, the 

 distance between the two ranges diminishing westward, while in the opposite direction it 

 must soon more than double. Judging from the arrangement of the pebbles, which, as 

 already noticed, are half derived from limestone, the direction of the old drainage must have 

 been from west to east, and must have formed the head- waters of the Aksai river, which on 

 the maps is recorded as rising a short distance east of the Chadyr-kul. Similarly, the gravel 

 valley between the Koktan and Artysh ranges indicates a west to east drainage, and its width 

 appears to have approximately averaged 20 miles. About 3 miles north of Chung-terek 

 a secondary old valley exists, also extending from west to east, and is diametrically cut 

 across by the Toyanda river. In this valley, which was formerly tributary to the one lying 

 more southward, the gravel beds accumulated to a thickness of fully 100 feet. As the 

 Artysh range did not offer a sufficiently high barrier, masses of the gravel passed locally 

 over it or through its gaps into the Kashghar plain, which itself at that time formed a third 

 large broad valley. 



Thus, at the close of the volcanic eruptions in the hills north of Chakmak, we find 

 three river systems all flowing eastward, and made more or less independent of each other 

 by mountain ranges, about which it would, however, not be fair to theorise (in the present 

 state of our knowledge) on the causes of their assumed relative position. It must have been 

 at that time that the pebbles of protogine were brought down from some portion of the hills 

 lying to the west ; and it would be interesting to ascertain whether or not this rock is any- 

 where in that direction to be met with in situ. 1 When the turbulent times of Vulcan's reign 

 became exhausted and tranquillity was restored, the whole country south of the axis of the 



1 In Severtzof 's journey to the western portion of the Thian Shan (Jour. Roy. Geogl. Soc., 1870, pp. 352, &c.) metamorphic rocks 

 are stated to be largely developed in the ranges further to the north-west. A large tract of geologically unexplored mountains 

 intervenes, however, between the southern limits of Severtzof 's examination and the Chadyr-kul. Baron Osten-Sacken's journey 

 vid the Chadyr-kul, from Vernoye to the neighbourhood of Kashghar (Jour. Roy. Geogl. Soc., 1870, p. 250), contains scarcely any 

 infprmation as to the geology of the countries traversed. He does not even notice the volcanic rocks south of the Chadyr-kul. 

 See remarks at the end of Part V, p. 33. 



It is perhaps as well to point out here, what will probably have occurred to many geologists who have read thus far. The 

 geological school to which Dr. Stoliczka belonged has not, I believe, accepted the views prevalent amongst most English geologists as 

 to the extent of subaerial denudation. It is far from improbable that some of the geological phenomena attributed by Dr. Stoliczka 

 to subsidence might by other observers be considered as a simple effect of disintegration and removal by rain-water. 



