28 
SECOND YARKAND MISSION. 
which appear to have taken place at the close of the csenozoic epoch within the southern 
offshoots of the Tliian Shan which we visited. 
Short as our sojourn in the mountains was, it proved to he very interesting and equally 
instructive. Humboldt’s account of the volcanicity of the Thian Shan, chiefly taken from 
Chinese sources, receives great support ; hut we must not speculate further beyond confid- 
ing in the expectation that both meso- and caenozoic rocks will he 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 Chun°*-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 harrier, 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 fan* 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 hill s 
lying to the west; and it would he interesting to ascertain whether or not this rock is any- 
where in that direction to be met with in situ} 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. Hoy. Geogl. Soc., 1870, pp. 352, &c.) tnetamorphie rocks 
are stated to he largely developed in the ranges further to the north-west. A large tract of geologically unexplored mountain* 
intervenes, however, between the southern limits of Severtzof’s examination and the Chadyr-kul. Baron Osten-Sacken’s journey 
vid the Chadyr-kul, from Vemoye to the neighbourhood of Kashghar (Jour. Koy. Geogl. Soc., 1870, p. 250), contains scarcely any 
information 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 poiut 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. 
