208 EXPLORATIONS IN TURKESTAN. 
One of the most important points in a further stndy of the climatic changes 
of Turkestan is to establish the correlation between individual moraines of known 
epoch and individual terraces. This seems to be possible, for in man)- cases the 
moraines themselves are terraced, while elsewhere, as in the valleys of the Kara 
Kul Su and Mudinim Su, moraines have been deposited upon terraces. One of 
the most promisin<j places to study this relation is in the Alai basin ; another, equally 
good, though less accessible and less beautiful in sceuer)-, is the headwaters of the 
Narin River. 
LAKES. 
Evidence of climatic change has also been found about the lakes of Turkestan. 
One of these, Issik Kul, has been described by Professor Davis in his report on the 
first month of our joxiruey in Turkestan. Another, Chadir Kul, has been consid- 
ered in a preceding section on the Tian Shan. Both of these are now without outlets, 
although a slight rise of the water would cause them to overflow as they have done 
in the past. A study of their old outlets shows that they have overflowed once or 
twice at least, probably under conditions of greater rainfall than to-day. 
Two other lakes were seen, of which only one, Kaplan Kul, has an outlet. 
This is an insignificant little sheet of water about a mile long, lying at an elevation 
of 5,500 feet on the northern slope of the Alai JMountains, 30 miles southeast of 
Osh. All along the lake margin, especially on the southern side, there is a broad 
belt of dense reeds, 12 or 15 feet high ; the open water in the middle seems to be 
only a foot or two deep, as herons wade about in all parts of it. The natives say 
that twenty years ago the lake was much more extensive than now and reached 
beyond the area where the reeds at present grow — a statement which the appear- 
ance of the shores amply supports. At the outlet a fair-sized brook cascades over 
3 or 4 feet of hard blue clay, the lake's own deposit, and flows away in a little 
channel 10 or 15 feet deep, cut in fine gravel and clay. The lake basin is merely 
a broadening of a stream valley due to the softness of certain red sandstones. 
Below what is now the outlet of the lake the soft strata are interrupted by a harder 
band of limestone which has prevented the stream from cutting rapidly downward, 
and thus gave it an opportunity to widen the valley upstream, while downstream 
there is a steep descent to another series of soft beds. Where the valley crosses the 
limestone, and consequently is narrowest, gravel was at some time washed in from 
the valley sides in such quantities that the slow-moving stream could not carry it 
all away, and thus a dam was fonned, behind which rose the lake. The formation 
of the dam indicates a time of more intense weathering, and therefore probably 
corresponds to the last glacial epoch. The barrier which confines the lake has now 
been almost ciit through, and in a few years the basin will again be empty. 
Shor Kul. — The fourth lake (fig. 145), is the most important as an indicator 
of climatic change, as it is completely inclosed by mountains and has never had an 
outlet. It lies at an altitude of 5,000 feet, 80 miles northeast of Kashgar, in one 
of the subsidiar)' basins in the borderland between the Tian Shan plateau and the 
Kashgar basin. Shor Kul, as it is called, means " Salt Lake," and the name is 
well deserv^ed, for the lake is a sheet of salt rather than of water. When I saw it 
