GEOLOGY. 29 
Liian Shan must have greatly subsided, and the wider the valleys, the more effectively 
\ as t to extent of subsidence felt. To support this idea by an observation, I may notice 
u- north of Chung-terek, at the base of the Koktan range, the Artysh beds have entirely 
T^appeared in the depth, and the gravel beds overlying them dip partially under the 
nas imestone, — a state of things wdiich cannot he explained by denudation, hut only by 
subsidence and consequent overturning of the older beds above the younger ones. A similar 
a e °* things is to be observed on the Terek range, where the young tertiary limestone 
cong omerate is in some places of contact overlain by the much older dolomite. Now, if the 
d !’ ( j a TaIle y °f the Kashghar plain sank first, and gradually lowest, as it in all probability 
lc > w o find a more ready explanation of the large quantities of loose gravel pouring into 
and accumulating at the base of the Artysh range. 
he sinking in of the volcanic centre north-west of Chakmak first appears to have 
l anied off the former head of the Aksai river, making it the head of the Toyanda instead ; 
oT t° the north of the Terek ridge it was most probably the cause of the origin of the 
iadyr-kul. The subsidence of the country followed in the south, making it possible for the 
ai aited Suyok and Toyanda rivers to force their passage right across the Koktan range, 
^U'ngthen the Artysh river, cut with facility through the Artysh range, and join the Kashghar 
^ ana. ‘While thus indicating the course of the comparatively recent geological history of 
® ground, it must be, however, kept in mind that this change in the system of drainage 
t j no essential effect upon the direction of the hill ranges. This, dating from much older 
? les ’ was mainly an east- westerly one, following the strike of the rocks which compose the 
10 6 mountain system. 
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