RECONNAISSANCE IN CENTRAL TURKESTAN. 211 
of silt is thinner than elsewhere and has often been broken through by erosion. 
According-ly at these points the water finds a ready exit and bubbles upward because 
it is under pressure. It is, however, possible that the deposits of which the hills 
are the remnants may belong to an earlier time than that mentioned above. This 
point and others had to be left unsettled on account of the short time allowed for 
the writer's journe\- and of the peculiarh- unfavorable conditions of xniseasonable 
rain and mud experienced at Shor Kul. 
Let us now turn to the more direct evidence of the double rise of the lake. 
During the first expansion, when the lake reached its maximum size, the water 
seems to have stood about 350 feet above the present level. On the north side of 
the plain, a little below this height, there is a sudden transition from coarse, angular 
gravel to the finest silt without a trace of pebbles. The gravel is subaerial waste 
of the normal type for an arid mountain region, and is now being slowly pushed 
forward over the silt. The silt could hardly have been deposited an^-where except 
iu a lake, for under almost any conditions of climate some gravel would be included 
in a deposit so close to the base of the mountains, unless it was laid down a little 
offshore in standing water. At the west end of the plain, southwest of Kirk 
Bulak, there is at the same 350-foot level a small bench and cliff, cut for about half 
a mile in the silty grav'el which there cloaks the mountain flanks. At the opposite 
end, near Pchan, a large compound fan of gravel has cloaked the lake silts smoothly 
as high as 130 feet above the present lake level ; but at an ele\ation nearly 400 feet 
from the water the gravel has a different fonn. At the lower le\el the gravel cloak 
is spread smoothh- and the streams wander across it in numerous shallow and e\-er- 
changing channels. Above a height of 400 feet the gravel is well dissected, and 
each stream has a single, definite terraced valley. 
On the south side of the lake the plain rises more rapidly and the old lacustrine 
deposits are considerably dissected, perhaps because of a slight warping. Never- 
theless there are the same lacustrine silts and subaerial gravels as on the north side, 
and the silts end at about the same height, that is, a little over 350 feet above the 
lake. Elsewhere old lake silts are found up to a height of 200 or 300 feet abo\e 
the water, where they begin to be covered with gra\el. It seems quite clear that 
the lake once stood 300 or 400 feet higher than to-day. 
At a place called Dungsugot,* on the .south side of the plain, 4 or 5 miles 
from the western end of the lake, there is good evidence of a second rise of the 
lake separated from the first rise by a period when the water retreated nearly or 
quite to the present level. Here the older lake deposit is considerably dissected 
(fig. 148), probably because the slope of its surface is much stee{)er than elsewhere. 
The valleys car\-ed in the deposits show three terraces which extend out to the 
fronts of the spurs, and even around them, from valley to valley. The spurs are 
flat-topped and for the most part are made of lacustrine silt. On the top, however, 
is a layer of gravel only a few inches thick at first, but gradually increasing in 
*Tlierc is a spring at Dungsugot where a camp could be made from whicli the terraces and lake 
deposits could be minutely studied. Fodder for horses would probably have to be brought from 
one of the villages 6 or 8 miles away. 
