io8 
EXPLORATIONS IN TURKESTAN. 
a change from a glacial to a tionglacial epoch. It would be an aid in the elucida- 
tion of these changes if soundings could be made to determine how far the pied- 
mont slopes continue their present declivity under the lake, and how far forward the 
valle\s may be traced. This would be of especial importance in connection with 
the ruins that are found submerged in the lake, as mentioned below. 
The onl)' suggestion that we can make as to the date when the piedmont waste 
slopes were formed is based on the occurrence of the moraine, already described as 
standing a little forward from the mouth of a valley in the Kiuigei Ala-tau, north 
of Choktal post station, about 1,500 feet over the lake. If one may judge by the 
relation of moraines and aggraded waste slopes elsewhere in the world, it is probable 
Fig. 73.- -A Drowned Valley in the Plain al the east end ol Issik Kul, looking northeast. 
that the formation of this moraine and the aggradation of the piedmont slopes 
were contemporaneous ; hence the erosion of the valleys is of later date than the 
glacial epoch in which the moraine was found. Inasmuch as the moraine here 
referred to was the lowest one that may have been fonned in its valley, it apparently 
belongs to the earliest of the glacial epochs established in Mr. Huntington's report. 
It appears from the foregoing that the Issik Kul basin has long been suffering 
disturbance and receiving waste from the surrounding mountains, and that the 
latest disturbances of level have been greater at its eastern than at its western end. 
We have next to consider the more modern history of the lake itself. 
