THE USBOI CHANNEL. 39 
the two. So, in 1881, wlicii Koiisliiii first saw the Usboi, he also took it for the 
old path of the Amu (18S6, 380), l)ut on further examination he concluded that 
while the depression in which the Usboi is eroded had served as a strait to unite 
the expanded Aral and Caspian seas, it had never sen-ed as the path of o\-erflow 
from the Aral to the Caspian, and that the river-like channel along the axis of the 
depression was the work of local wet-weather streams (1886, 427-431) ; but it should 
be noted that one reason for this conclusion was the deductive belief that the Aral 
could not have had a water supply sufficient for overflow after the climate had 
become so dv}- as to cause the Caspian to shrink below the Aral level (1886, 428). 
Some ten years later (1895) Konshin reversed this earlier opinion, and treated 
the Usboi as the channel carv-ed by the Aral overflow outlet. He still maintained, 
however, that the Amu had never flowed directly into the Usboi, and in evidence 
of this he pointed out that there was no channel leading from the Amu to the head 
of the Usboi ; that the Sary-Kamish depression lay between the two, and that the 
Usboi channel was decided!}- smaller than that of the Amu to-da)-. More than one 
writer notes the absence of canals and ruins along the Usboi, and concludes that the 
river which eroded the channel must therefore have been salt and unattracti\'e to 
settlement. This conclusion mifortunately begs the important question of the 
existence of a house-building and canal-cutting human population at the time the 
Usboi was formed. No independent proof of man's existence at that time and in 
that place has yet been found. In this connection the levels at some critical points 
may be introduced. Bala Isliem, 336 feet (72 meters) above the Caspian, is at 
the divide between the Aral and the Caspian districts ; the Usboi is eroded on the 
gentle slope southwest from the divide ; no channel occurs on the northeast slope. 
Sary-Kamish is the name of some .salt lakes in the bottom of a depression north of 
Bala Ishem, 50 feet (15 meters) below the Caspian, whose separation from tiie Aral of 
to-day may be due to the growth of the great Amu delta between the two basins. 
Walther quotes various other altitudes (1898,212). As the Amu now enters the Aral 
alone, the fonner waters of the Sary-Kamish depression have been e%-aporated almost 
to dryness, thus repeating the case of the Colorado River at the head of the Cnilf of 
California. The I'sboi channel nuist have lengthened southwestward as the Caspian 
retreated, thus producing features similar to those well known in the Bonneville 
basin of Utah. It is pertinent to quote in this connection Semenofs obser\-ation 
that the plain bordering the Caspian southeast of Krasno\odsk appears to be the 
remains of spacious deltas fonned by large rivers which for man}- centiiries here 
entered the sea from the east (1888, 292). Konshin (1887, 237) notes that Caspian 
shells are abundant on the desert plain for 125 miles (200 km.) east of the present 
shore and up to nearl}- 200 feet (60 meters) above the present level; but the}- are not 
mentioned in association with the .shorelines of the Ungus. Obmchef gives similar 
statements (1890, 246). 
Tliere seems to have been comparatively little discussion of the relation of the 
Quaternary Aralo-Caspian in Turkestan to the climatic changes of the glacial 
period. .Sjogren (1888) cxjilains the ex]>ansion of the sea b\- the greater volume of 
water received from the glaciated area of northern Russia, and suggests that as far as 
