RECONNAISSANCE IN CENTRAL TURKESTAN. 
205 
nor does this show the full complexity of the problem. In the valley of the 
Ispairan Su, south of Marghilan, for example, gravels of two and possibly three 
ages can be detected. The oldest is a very coarse deposit three or four hundred 
feet thick, which is cemented into solid conglomerate by calcite from the limestone 
walls. A deep valley was then cut in the conglomerate, so that its remaining 
portions form a terrace several hundred feet above the stream (fig. 144). This valley 
was then filled, though to a much less height than before, with gravel of the same 
sort as the first, except that it is not cemented so firmly into conglomerate. In 
this second conglomerate another valley has been cut ; and there are places where 
the filling and cutting seems to have been repeated a third time on a still smaller 
•-a.'*>S-.»J»'»aA-.v . 
■■s%.-M<>ji.-; - 
Fig. 142. — Terrace wall of the Kan Su, west o( Kashgar, showing horizontal gravel above tilted Mesozoic strata. 
On the left or north side are the coal measures; on the right are the vermilion-red beds. Between the two 
can be detected a slight unconformity, A. 
scale. If all this is due to defonnation it means that there has been an extraordinarily 
complex series of palpitations — now up, now down — and that while the upward 
movements ha\-e been parallel over large areas, the downward mo\-ements have 
occurred erraticall)- here and there in such a way tliat the terraces of valleys close 
beside one another are of different types, or that the upper part of a valley has 
merely been cut again and again, while the lower part has been both cut and filled 
an equal lunnber of times. If, then, the theor}- that the terraces are due to move- 
ments of the crust can not be said to be absolutely untenable by reason of the 
coniplicatious that it involves, it certainly matches the facts only indifferently well. 
