EXAMPLES OF TERRACES. 
255 
of Askhabad. In both these regions there were well-marked series of terraces, 
indicating a succession of decreasingly severe impulses toward valley deepening. 
Whether the cause of these terraces was to be found in cnistal movements or in 
changes of climate could not be determined becau.se of the small number of exam- 
ples, either cause seeming to be competent to explain all the phenomena. Farther 
east along the northeni slope of Kopet Dagh the same state of affairs continues 
indefinitely. At Anau, 6 miles east of Askhabad, a small stream breaks through 
a gorge in the front range of Kopet Dagh and debouches upon the piedmont plain, 
where its waters are diverted for irrigation. In its upper course the Anau stream 
flows northwestward through a broad valley of soft strata, which were depressed to 
their present level by the fault which uplifted the small Anau ridge on the northeast 
side of the valley. This Anau ridge appears to be a fault block of the same sort as 
that of Suru-Muzdar, which lies on the southwestern side of the valley and has 
been described b}- Professor Davis. In both of these parallel blocks the south- 
west side presents a precipitous escarpment, the battered successor of the original 
fault scarp, while the northeastern face presents a smoothly-graded slope in which 
are incised the deep trenches of small consequent streams. In the Suni-Muzdar 
Oi 6=course of brook ; c, default ; l^liniestone ; 2=conglomerate ; 3=-red silt ; 4=gravel ; 5— soft 
Tertiary fonnation. 
Fig. 136. — North and south section along the Anau Brook, across the Anau fauh block. Dash lines 
indicate terraces. 
block, so far as could be judged from a distance, the back slope appears to be 
wholly stnictural, following the bedding of the hard Cretaceous limestone. In 
the Anau block, on the other hand, the tipper part of the back slope is determined 
by the structure of the limestone, while the lower part is quite independent of 
structure and truncates the underhing warped Tertiary strata (fig. 156). Where 
the Anau stream turns to the north and passes out of the trough between the two 
fault blocks it has cut a deep gorge in the Anau block. The sides of this gorge 
are steep, but even at the narrowest point the bottom is flat-floored and has a width 
of several hundred feet, so that although the gorge is young there nuist ne\erthe- 
less have been a considerable lapse of time since its cutting was begun, and even 
since it was cut to its present level and the work of broadening the bottom began. 
The Anau gorge is important becau.se of the terraces which it contains. As is 
seen in the cross-section (fig. 156) the stream, on leaving the soft strata south of the 
Anau fault block, first traverses a hard limestone forming the narrowest portion of 
the gorge, and then a coarse conglomerate, and lastly a red silt already described as 
like the silts of Kashgar and Bajistan. Overlying the conglomerate and silt, both 
of whicli ha\'e been warped and dip northward, extends a recent conglomerate or, 
