140 EXPLORATIONS IN TURKESTAN. 
these bluffs showed a peculiar distortiou, being, in most cases, bent into an arch, to 
which tlie mound surface is concentric and confonnable in vertical section (fig. 102). 
While wandering among these iiillocks we suddenly came upon an elliptical 
lake about i ,000 feet by 700 feet, with its long axis pointing directly toward Kara 
Kul. Its surface was 10 to 30 feet below the level of the plain, the walls every- 
where extending vertically down into clear, deep water. At first there seemed to 
be no reason for its existence, there being no hydrographic relation with the 
surrounding topography. Professor Pumpelly suggested tliat " lol)cs of ice liad 
been buried by the sediments ; the slow melting had deprived the sediments of 
their support, and the roof tumbled in, probably recentU', leaving the deep pool." 
Perhaps a more gradual sinking of the surface, occurring as the buried ice melted, 
is what has gixcn these areas tlieir hillock topography and distorted stratification. 
Professor Davis suggested that the solution of tlie underlying .salt deposits could 
ha\e resulted in the same conditions. 
Some versts north of this region there is a moraine sloping under the Kara 
Kul sediments ; this could have pushed its way imder water, weighing dowu the 
glacial ice that carried it, while the lake depositions covered it with clay .sediments. 
In this way large masses of ice could be buried beneath the sediments. 
Fig. 103. — Moraine of the Kara Kul Basin, looking northwest on the Older Moraine. An overriding Moraine seen in 
the distance on the right. 
OBSERVATIONS ON THE GLACIAL GEOLOGV OF THE GREAT KARA KUL BASIN. 
The data obtained on the glacial .geology- of this basin conform very well with 
the glacial history in the Alai Valley. Here, also, we find evidence of two long- 
separated glacial epochs and indefinite indications of a third advance of little extent. 
The Kara Kul sediments seem to have been largely deposited between the first 
two epochs established. The older moraines, as seen north of the lake, are in the 
fonn of smoothed-ofF masses rising out of the stratified lake clays, and made up of 
semi-angular bowlders of crjstalline limestone, black slates, red sandstone, gypsum, 
granite, and greenstone. Where observed the\- were below the 200-foot level and 
had clearl)- been worked over by the lake, which has left numerous bars and beaches 
of cobbles (fig. 103). A distributary of the Kok-sai darya has cut a very broad, flat- 
bottomed channel through one of these old moraines. 
