PHYSIOGRAPHY OF CENTRAL-ASIAN DESERTS AND OASES. 
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THIRD EROSION CYCLE. 
To us the third cycle is most interesting, as it overlaps the second glacial 
epoch and less time has elapsed to obliterate its records. As a result of its uplift, 
apparently warped, the river cut down through the alluvial fillings of the second 

Fig. 455.—Ice-cave of the Zerafshan, Looking from within. 

Fig. 456.—Terraces of the Zerafshan. 
cycle and into the old rock bottom to a depth of from 50 feet in the lower to 300 
feet in the mid-warp part of the valley with a canyon about as wide as the present 
and reaching about the same depth. Then the uplift appears to have stopped 
