44 
EXPLORATIONS IN TURKESTAN. 
can not be foretold. Embankments or dikes are therefore thrown np in oblique 
lines on the ii])-slope from the track, so as to gfiiide the floods toward strong cuh'erts 
under the roadbed. Yet even these safeguards do not alwajs suffice. Not long 
after we left this part of the country the news o\-ertook us of a destmcti\'e flood 
b\' which a jxirt of the track near Kizil-Arvat had been washed away. 
The irregular structure of the piedmont slope, as exposed in cuts along the 
railroad line, is well described by Walther (1900, 104). There is a frequent and 
irregular alteration of stratified or massive loess-like clay, finely stratified sands, and 
coarse gravel, with many local unconfonuities ; all this being the result of the 
variable action of floods that sweep suddenly, unguided by channels, down the 
Fig. 24. — A Barkhan near Bakharden, looking south. 
piedmont slope ; now eroding, now depositing ; here sweeping along coarse blocks, 
there depositing fine silts. Ten miles south of Askhabad, where the railroad station 
is 819 feet altitude, we saw, when returning by the Meshed road from an excursion 
in the Kopet Dagh, more abundant piedmont deposits of moinitain-waste dissected 
to depths of several hundred feet. A great thickness of these deposits has been 
penetrated by the artesian boring in the suburbs of Askhabad, already mentioned, 
2,000 feet deep, and therefore with more than half its depth below sea level, but 
without securing a water supply. The whole depth, as shown in the record quoted 
by Walther (1900, 105), is in variable layers of clay, .sand, and gravel, similar to the 
deposits seen in the borrow-pits near the railroad embankments, or in the natural 
