PART 3 .] 
Stoliczka : Visit to the Chaderkul. 
85 
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 headwaters of the Aksai liver, which on 
the maps is recorded as rising a short distance east of the Chaderkul. Similarly, the gravel 
valley between the Koktan and Artush ranges indicates a west to east drainage, and its width 
appears to have approximately averaged 20 miles. About three miles north of Chungterek 
a secondary old valley exists, also extending from west to east, and is diametrically cut 
across by the Toyan 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 
Artush range did not offer a sufficiently high barrier, masses of the gravel passed locally 
over it or through its gaps into the Kashgar plain, which itself at that time formed a third 
large broad valley. 
Thus, at the close of the voleayic 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 theorize (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. When the turbulent times of Vulcan’s reign 
became exhausted and tranquillity was restored, the whole country south of the axis of the 
Thian Shan must have greatly subsided, and the wider the valleys have been, the more 
effectively was the extent of subsidence felt. To support this idea by an observation, I may 
notice that north of Chungterek, at the base of the Koktan range, the Artush beds have entirely 
disappeared in the depth, and the gravel beds overlaying them dip partially under the 
Trias limestone, a state of things which cannot be explained by denudation, but only by 
subsidence and consequent overturning of the older beds above the younger ones. A similar 
state of things is to be observed on the Terek range, where the young tertiary limestone 
conglomerate is in some places of contact overlain by the much older dolomite. Now, if the 
broad valley of the Kashgar plain sank first, and gradually lowest, as it in all probability 
did, we find a more ready explanation of the large quantities of loose gravel pouring into 
it and accumulating at the base of the Artush range. 
The sinking in of the volcanic centre north-west of Chakmak first appears to have 
drained off the former head of the Aksai river, making it the head of the Toyan instead; 
and to the north of the Terek ridge it was most probably the cause of the origin of tho 
Chaderkul. The subsidence of the country followed in the south, making it possible for the 
united Suyok and Toyan rivers to force their passage right across the Koktan range, 
strengthen the Artush river, cut with facility through the Artush range, and join the Kashgar- 
daria. While thus indicating the course of the comparatively recent geological history of 
the ground, it must be, however, kept in mind, that this change in the system of drainage 
had no essential effect upon the direction of the hill ranges. This, dating from much older 
times, was mainly an east-westerly one, following the strike of the rocks which compose the 
whole mountain system. 
Kashgar, 
1 ()th January 1874. 
