jS EXPLORATIONS IN TURKESTAN. 
as well as many smaller fans at the base of other ranges, showed no signs of 
faulting. Their radial slopes were smooth and unbroken. The small range or block 
C, fig. 43, appears to be cut off from the larger block, B, b\- the gorge of the Urta- 
takoi (Chu) River. The post-road goes north through the gorge, but we turned 
eastward and followed the aggraded trough between ranges C and D, directly to the 
lake. A drs-stream bed, gathering all the wa.sh from the piedmont gravels of the 
much higher range, D, on the south, was pushed close to the base of the back slope 
of the smaller range, C, on the north, sometimes e\en undercutting the base of its 
spurs. The northern range was, where we saw it, composed of rough conglomerates 
and sandstones, dipping steep to the south, and to all appearance much older than 
the modern conglomerates of the Issik Kul basin. Their strike to the east-northeast 
ran obliquely to the trend of the range. The strata were obliquely truncated b\- the 
general back slope of the range, as in figure 44. The conglomerates and sand 
stones, generalh' dull-red on fresh surfaces, 
were so darkh' weathered with "desert 
varnish " that we at first took them to be 
basaltic lavas ; they were often cut by black 
Fig. 44.— Ideal Secrion from Range C to D, Figure 43, dikcs. The northern face of this range was 
looking east. , , i t^ 
much steeper than the southern. Range 
D, on the south, gave no conclusive evidence of block-faulting, for it was much 
dissected ; but its comparatively straight northern base-line and the great body of 
waste that has accumulated beneath it are suggestive of differential movements, with 
the appropriate consequences of degradation of the uplifted block and aggradation 
of the depressed block. A few knobs of rock rise tlnough the piedmont gravel slope. 
They may be interpreted as remnants of narrow blocks, on Gilbert's theory of 
faulting, or as remnants of a broader mountain mass on Spurr's theory' of compound 
erosion of the Utah-Nevada ranges. 
The Kungei Ala-tau, north of the west end of Issik Kul, is a dissected block- 
like mass with a plateau-like crest. It rises and becomes more and more dissected 
to the east. There is much evidence of subordinate faulting along part of its 
southern base, as will be more fully set forth in the chapter on Issik Kul. North 
of the middle of the lake this range is of well-developed Alpine form, with cirques 
and glaciers that are further described in the chapter on glacial records. 
It may here be noted that earthquakes, of no infrequent occurrence in the Tian 
Shan, are regarded by Mushketof (1890) as due to movement on fault lines along the 
base of certain ranges, the Alexander range being one. The shocks by which 
Vyemyi was destroyed on May 28, 1887 (O. S.), were ascribed by this observer to 
a fault along the northern base of the Trans-Ili Ala-tau. The shocks continued for 
about two years. Wosnessensky (1888) showed that they \-aried with the changes 
of atmospheric pressure, increasing with the occurrence of low pressure. We were 
told that Sazanovka, a Russian settlement on the north side of Issik Kul, was 
destroyed by an earthquake six years ago. 
