212 
EXPLORATIONS IN TURKESTAN. 
thickness toward the inouiitains. The gravel extends down the slopes of the 
terraces (fig. 146), but at the bottom it is abruptly covered by another deposit of 
lacustrine silt. On the latter there is nowhere any gravel except in places where 
it is now creeping down from the terraces, or where a stream comes out from the 
mountains and is now covering its broad flood-plain with a thin coating of pebbles. 
A=bed-rock. B=lake silt of 350-foot level. C=first terrace and layer of gravel coveriug silt. 
D=second terrace. E=third terrace. F=liill with springs. G=lake silt of 100-foot level. 
H^lake. I=edge of mountains. 
Fig. 146. — North and south section of the plain of Shor Kul from the lake lo the mountains at Dungsugot, 
In the valleys the lower terraces are not cut in silt, as is the case on the fronts of the 
spurs toward the lake, but in gravel deposited in the valley after it had been cut 
below its present depth (fig. 147). The reader will at once perceive that fig. 147 
is almost identical with the cross-section of the Ispairan Valley (fig. 144), and will 
doubtless infer, as the writer does, that both are the effect of a similar series of 
climatic changes. 
Fig. 147. — Cross-section of a Valley cut in the silt at Dungsugot. For explanation see fig. 146. 
mh All the phenomena of Shor Kul are satisfactorily accounted for by the same 
theory- which explains the old moraines and the terraces. The earliest record of the 
lake was at the stage of greatest expansion ; the silts of the 350-foot level were 
then laid down. Later the climatic conditions changed, so that the lake shrunk 
almost, if not quite, to its present size. Gravel at once began to creep forward 
over the silt, and, as the surface was very smooth, the streams wandered widely and 
covered the whole lacustrine plain with a layer of pebbles. In time, however, the 
amount of waste from the mountains grew less under the influence of the changed 
