I50 
EXPLORATIONS IN TURKESTAN. 
The first traces of floor A are found as long sloping spurs, projecting trans- 
versely into the valley below Taldic pass. Extending down the \alley, it rapidly 
broadens out on alluvium-covered terraces, and appears to ha\e emerged on to a waste- 
covered piedmont plain, reach- 
ing to witliin 25 versts north 
of the present Alai range axis. 
This plain has now been exten- 
sively dissected, and remains 
only in frequent flat-topped hills 
capped with horizontally hing 
conglomerate and in the sharper 
tops of other hills and spurs 
reaching to the proper height. 
It will be seen by the profile 
that it spreads horizontally to 
the north from the range axis 
and remains in terraces and al- 
luvium 3,500 feet above stream 
at Gulcha. There were higher 
hills that rose as residuals from 
the alluvium covering portions 
of the level of floor A (fig. 112). 
Reaching a point about 3 
versts down the valle>- from 
Taldic pass, the stream emerges 
abruptly from its torrent gorge 
into the wide valley at Ak-Busa- 
Ga. The accompanying sketch 
map (fig. 115) gives a rough 
idea of the dimensions of the 
plain of the valley floor and posi- 
tions of the main stream and 
tributarj' channels at Ak-Busa- 
Ga. Here we find a transitional 
state. The trunk stream has 
sunk a channel 15 feet deep 
through the grass plain and into 
alluvial conglomerates, while the 
side tributaries pass over falls 
into their gullies leading to it. 
Since these falls are some dis- 
Fig. 1 15. — Map of the Ak-Busa-Ga grass plain and stream channels. 
tance from the plain border, it is evident that these streaiTis ha\-e not had time to 
cut back into their respective vallej's since the trunk channel was sunk. Passing 
down through Ak-Busa-Ga outlet, we find that the grass plain is there higher above 
