are 
plained by MIDDENDORFF, WALTHER (p. 122) and SOLGER (p. 
149). In contrast to the dunes of western Europe, the barchans 
do not owe their occurrence to the sand having at first found 
shelter behind some obstacle, but they take that form which 
offers least resistance to the wind, hence they must be regarded 
as gigantic wave-lines in the sand. Good pictures of barchans 
may be seen in BESSEY. 
Other forms of sand landscapes are dealt with in the 
chapter on the formation of the sand desert. 
The Aralocaspian formations which originated in the 
post-pliocene Aralocaspian Basin consist of sandy clays de- 
posited on the bottom of the basin. The area of the older 
sea was considerably larger than that of the present lakes; 
thus, its eastern part extended down both sides of the isolated 
mountains Bukan Tau and Sultan Uis Dagh so that these 
occupied a peninsula in the sea. As the sea dried up, many 
smaller lakes were left. 
Loess, as is well known, is a calcareous loam inter- 
sected by innumerable irregular veins which often contain 
roots of plants. “Ein Leichenfeld von unzählbaren Genera- 
tionen von Gräsern”, as RICHTHOFEN puts it (I, p. 71). Loess 
is now generally regarded as an eolian deposit derived from 
dust-drift, since the finest material shifted by the wind — if 
not taken right away — must sooner or later come to rest 
either in water or on a fixed “steppe”, because the wind 
would carry it away again from any other place (RICHTHOFEN 
I, p. 98). In the first case the material will go to form stra- 
tified deposits on the sea-bottom, in the latter it will form 
land-loess which is not stratified. 
In Turkestan Loess may attain a great thickness, accor- 
ding to RomANowsk1 up to 1500 feet. It occurs more especi- 
ally in the south-eastern, southern and eastern parts of the 
territory, but also occurs in patches in other places (Musn- 
KETOW). 
Like all areas without drainage to the sea, the Trans- 
caspian plains are rich in salts, since if the products of 
disintegration and chemical weathering cannot be taken out 
of the country, they must remain. Most of the Russian 
authors known to me are of opinion that the salts origin- 
