THE ARALO-CASPIAN SEA IN THE KARA-KUM. 37 
The plains of southern Turkestan are described by Mushketof and others as 
occupjing an extensive area of depression which has received the waste washed 
into it from the surrounding higher lands. These higher lands are as follows : The 
Ust-urt plateau on the west is an uplift of late Tertiary- strata, being covered in its 
western part at least by the Akchlag\l formation of Andrussof (1902). Krasno\-odsk 
lies southwest of this upland, and the sections already given in fig. 20, as well as the 
escarpment of the Ust-urt farther east, suggests that the upland is bordered by a 
fault along its southern and southeastern margin. The Kopet Dagh, on the south, 
has been described by Bogdanovich (1887). The range is largely composed of 
Mesozoic and Tertian.- limestones, folded in a .somewhat orderly fashion, with axes 
trending west-northwest. The northwestern part of this line of disturbance is 
known as the Kurian Dagh, the Small and Great Balkhans, and the Kuba Dagh (the 
last rising back of Krasnovodsk). The farther extension of the same line leads to 
the Caucasus range. The plains are bounded on the east by the out-reaching 
members of the great mountain systems of Central Asia, well known to in\-ol\e 
late Tertiar>' and post-Tertiar)- uplifts, as will further appear in Mr. Huntington's 
report. To the north the plains continue far beyond the region here considered. 
The depressed area between these higher lands, the southern Turkestan depres- 
sion, is called a grnbcn by Mushketof, at least that part between the I'st-urt and the 
Kopet Dagh. It seems to have been kept below the surrounding highlands b}- 
repeated differential mo\ements, and it has therefore long been receiving their waste. 
It slopes away from the higher borders after the fashion of piedmont fluviatile plains, 
of which it seems to be in large part an excellent example. Its surface materials 
are coarse near the margin, but become finer farther forward. Many of the streams 
that descend from the mountains wither away on the plains; only the largest rivers, 
the Amu and the Syr, succeed in reaching the Aral. The Tejen and the Murg-ab 
disappear on the southern plains ; the Zerafshan, greatly reduced by use in irriga- 
tion in Bokhara, approaches but fails to reach the Amu ; and the Clui wastes away 
on the plains farther north. 
It is the district south of the Amu with which we are at present concerned. 
This part of the plains is chiefly a barren waste, the Desert of the Black Sands, the 
Kara-Kum. 
THE QUATERNARY ARALO-CASPIAN IX THE KARA-KUM. 
The deposits of the Pliocene Aralo-Caspian are described by some WTiters as 
underlying all the Kara-Kum, but there does not seem to be entire agreement on 
this point. The Ouaternar].- Aralo-Caspian is belie\ed to have been of less extent, 
but it has not been well defined in Turkestan (cf Mushketof, 1886, I, 696), probably 
because of the difficulty of exploration in the desert. Jakalof (1882) speaks of the 
general belief that the Kara-Kum is the bed of the expanded Aralo-Caspian Sea, 
but notes that sea shells are not found in the desert. Sjogren (1S8S) briefly states 
that the last rise of the Caspian covered the Kara-Kum. Konshin ( 1 896) gives a 
sketch-map of the sea, showing its area at the beginning and at the middle of the 
Quatemar}- period and at the opening of the present or historic period, and thus 
^o )4 6 
