RECONNAISSANCE IN CENTRAL TURKESTAN. 
187 
moraines grow fresher and yonnger in form from the lowest to the highest; and a 
long interval mnst have elapsed between the formation of No. i and No. 5. From 
the evidence snpplied by other valleys it seems that each moraine represents an 
advance of the ice after a considerable retreat; so far as the Jukuchak \'alley is 
concerned, however, the ice might simply have retreated by successive steps and 
the intervals between tlie steps need not have been of great lengtli. 
(2) Moraines of the eastern Klioja Ishken I 'alley. — Another valle)-, that of the 
Kok Su, or better, the eastern Khoja Ishken, shows the same succession of five 
moraines, which might all have been formed by one glacier in its successive retreats; 
but here erosion has been more active and the difference in age between the suc- 
cessive moraines is more marked. The first moraine lies at an elevation of about 
8,000 feet at the mouth of the Kok Su, where it enters the Kuzzil Su of the Alai 
Valley. Like all the moraines of this earlier age, it has completely lost the original 
glacial topography and is only to be distinguished by the bowlders it contains. These 
consist of slate ranging up to 1 2 or 14 feet in size, which might have been derived 
3, 4, s^nioraiucs of the third, fourth, and fifth glacial epochs. Ill, IV, V=level ot valley floor previous to the third 
fourth, and fifth glacial epochs. C, D, E— gravel deposited at end of third, fourth, and fifth glacial epochs. 
Fig. 131. — Longitudinal section of tfie Khoja tshken or Kok Su Valley. 
from close at hand, and of granite up to 7 feet in diameter, which nuist have been 
transported at least a dozen miles. The moraine is now entirelj' smoothed off and 
cut into four terraces. It lies on a thick deposit of river gravel which was probably 
laid down during the time just preceding the arrival of the ice. The second mo- 
raine is much like the first, except that it occasionally shows some of the original 
relief If this valley were examined without reference to any others, these two 
moraines would be considered parts of one. The third, fourth, and fifth moraines 
are all distinct and are separated l)y spaces where the valley is open and aggraded. 
They lie on rock terraces high alxne the brook, which, as it approaches each 
moraine, plunges into a gorge. In these gorges may be found a good measure of 
the length of time that has elap.sed since the several moraines were formed. 
Before discussing this aspect of the problem, however, it will be well to consider 
the origin of the gorges themselves. This is best explained by means of the 
accompanying diagram (fig. 131). The line III represents the valley bottom at the 
beginning of the third glacial epoch. The advancing glacier came down this slope 
