RIVERS AND VALLEYS OF THE TIAN SHAN. 
95 
We were led to conclude that the crustal movements during the deposition and 
the deformation of the Narin strata should be associated with the movements that 
have given rise to the present relief of the Tian Shan. The red color of the basal 
beds, seen not only on the south side of the Chaar Tash, but in the southern 
distance along the north base of the Kalkagar-tau, is consistent with the reduction 
Fig. 61 . — Four-mile section across the northern border of the Narin formation, looking east. 
of the region to lowland form before the beginning of the deformation by which 
the Narin deposits were initiated ; yet the inclosing ranges to-day have serrate 
crests without indication of having ever been peneplained. Some smaller valley 
deposits, probably of Tertiary- date, will be described in the next section. 
THE RIVERS AND VALLEYS OF THE TIAN SHAN. 
If the theoretical considerations presented in the chapter on the Tian Shan are 
well based, we should expect to find streams of several kinds among the western 
ranges of this mountain system. Those of the first kind would continue from the 
fonner cycle of erosion, but would be revived to renewed activity in consequence of 
a favoring elevation of the region. The \alleys of these revived streams would be 
seen to-day where the relief of the fonner C3-cle remained in greatest strength, or 
where the new uplifts did not defeat the streams. Streams of a second kind would 
persist from the antecedent cycle of erosion in spite of an unfavorable elevation 
of the region. The valleys of these antecedent streams would be expected where 
the streams were largest and where the unfa\'orable uplifts were not too strong. 
Streams of a third kind would be of new establishment, following the slopes 
produced by the movements which introduced the new cycle. They might be 
called new consequents, and they would be expected where the movements were 
strong and the pre-existent streanas were weak. A fourth class of streams would 
include all those developed in the new cycle by headward erosion along belts of 
weak structures exposed in the \-alleys of the other class. Such would be called 
new subsequents. 
Examples of revived streams are probably to be found in the central plateau- 
like region described in Mr. Huntington's report. The gorges cut through some 
of the ranges suggest an antecedent origin. The gorge by which the Narin cuts 
through the eastern end of the Chaar Tash, just below the entrance of the Alabuga, 
the gorge of the Juvan-arik in the Yukok-tau range (fig. 43), and the Buam gorge 
of the Chu northwest of Issik Kul, all may be of this kind ; but the case is not clear. 
New consequents appear to be numerous on the northern face and on the southern 
back slope of the Alexander range, and in the longitudinal depressions between 
the ranges near the west end of Issik Kul. New subsequents of relatively small 
size are probably of common occurrence as branches of all the other kind of streams. 
