PHYSIOGRAPHIC OP.SERVATIONS. 
149 
The Taldic Valley increases in depth from about 500 feet near the source to about 
3,000 feet just above Gulcha ; a little below Gulcha it emerges into a relatively 
shallow channel on the lowland plain, and finally joins the Kara dar\'a, a branch of 
the Syr. It varies greatlj' in width, according to the hardness of the rock. For 
about 15 versts, part in black silicious limestone, part in granite and hard slate, it 
Fig. ! 13. — Taldic Valley Terraces, looking up the Taldic Valley from Floor B, about 63 versls above Gulcha. 
Floor A is high up on the right. 
narrows to a deep canyon, where the stream is a roaring torrent running partly on 
ledge bottom. Where cut in the gypsum series it broadens out, with sides sloping 
back in successive steps over extensive terraces. Except where in the above-men- 
tioned canyon, the Taldic darya, from about 20 versts below its source to Gulcha, is 
directly contained in a channel of often rectangiilar cro.ss-section, averaging some- 
Fig. 1 14. — Taldic Valley Terraces, looking up the Taldic Valley from Floor C, about 46 versls above Gulcha, 
thing like 500 feet in width and 100 feet in depth, and cut in partially cemented 
alluvial conglomerate. When in high flood the stream covers the whole breadth of 
the bottom ; at other times it is largely split into smaller streams rejoining each 
other on its irregular gra\el flood-plain. The accompanjing profile of the stream 
has been constructed with the aid of Russian leveling notes, and tlie characteristic 
terraces have been projected onto it from my approximate measurements. These 
terraces have been lettered A, B, C (figs. 112-114). 
