DESERTS. 261 
ately so, and become of great interest as a demonstration of the origin of such 
nuclei in greater basins. Its wide gravel-plains sloping from the Trans-Alai are 
strewn here and there with dunes and other areas of loess, while in the lower half 
of the valley there are sand nuclei several miles in length. Several feet of loess 
have accumulated over its old moraines and along the lower slopes of its border 
ranges. 
GLACIOLOGY AND EVIDENCES OF MOUNTAIN MOVEMENT. 
The glaciology was described in my first report. The same oscillations and 
the same greater advances and recessions took place here as in the Kara Kul basin. 
During the two first epochs much of the valley steppe was occupied by wide pied- 
mont ice-flows extending all the way across it from the Trans-Alai. Moraines 
laid down during the first have lost all topographical characteristics and their 
worn-down surfaces now form broad, low, transverse undulations of the valley 
floor and massive foothills of the Trans-Alai. Those laid down during the second 

Fig. 439.—Kirghiz making Felt in the Alai Valley 
epoch are now spread in the form of broad lobes covering immense areas and made 
up of vast numbers of conical mounds. In one remarkable instance, a second- 
epoch glacier spread all the way across the valley, piling up the slope of its northern 
side, just west of the Kashka Su. Through this moraine the Kizil Su has cut a 
channel, exposing a section of till resting on alluvium barely above the level of 
the stream. This section is of especial importance, for it is clear proof that the 
Kizil Su flood-plain was at about the same level there during the second glacial 
epoch as it is to-day, and that terraces, which leave the flood-plain about half- 
way down the valley and attain a height of 300 feet near its outlet, belong to 
some earlier age. 
On a visit to the glacier of the Tokuz Kungei, one of the greater Trans-Alai 
tributaries to this valley, some ideas were formed about the third and fourth 
epochs and their relations to the older. This glacier still terminates piedmont 
fashion, deploying—over a massive accumulation of moraine filling the mouth 
