EXAMPLES OF TERRACES. 257 
from passing trains shows that ahnost universally the " ateck," or " skirt " of the 
mountains, as the Turkomans tenn the piedmont slopes, has been subjected to a 
slight dissection. The numerous coalescent fans are intersected by small dn,- valleys, 
the peculiar feature of which is that they are not fresh, but are everywhere grassed 
over, while the sides are reduced to a very gentle angle and the bottoms appear to 
be half filled with sediment. They are certainly not channels which are now being 
eroded, and they seem to extend farther than the farthest floods of to-day. It is 
possible that they belong to a rather recent time when the streams flowed farther 
out into the desert than they do to-day. The largest stream of the district is at 
Lutfabad, where the railroad crosses the lower waters of the stream whose terraced 
upper portions have been described by Professor Da\ is. Here, where the stream 
spreads out upon its fan shortly before coming to an end, it is bordered by two 
distinct terraces. 
From Dusliak southeastward for 80 miles to Serakhs, at the northeastern corner 
of Persia, on the Heri Rud, or Tejen River, I traveled b}- caravan and was able to 
examine the countr\^ more closely. Few new features were seen, however. Near 
the mountains the fans are naturally more arched and more gravelly than farther out 
toward the plain. Curiously enough, the old stream channels do not take the form 
of depressions, but appear as incipient ridges topped with a belt of cobble stones, 
some of which are 6 or 8 inches in diameter. Apparently at some previous time 
the streams deposited cobbles along the floors of their channels. Since that time 
the fans have been so far degraded that the channels have disappeared and their 
floors have been converted into ridges. The present streams are incised below the 
plain to depths of from 10 to 15 feet, or even more. All that were seen were small 
dry channels, with the exception of the flowing streams at Meana. 
THE MURG-AB RIVER. 
Omitting for the present the Heri Rud (river), which comes from the interior 
of the Iran basin, one more stream must be described, which flows from the northern 
side of the mountains. The Murg-ab, i. e., Murg-water, rises in the Paropamisus 
Mountains in northwestern Afghanistan, and flows northward into the desert of 
Transcaspia, where it finally loses itself in the reed-beds of a swamp after watering 
the flat oasis of Merv. At Merv itself and throughout the oasis the main stream 
flows practically on the surface of the delta, although some of the irrigation canals 
are incised 10 or more feet Upstream, however, the delta is bounded by cliffs of 
silt, which gradually converge and grow higher until at the dam of Hindu Kush, 
30 miles above Merv, the river flows in a well-defined valley. At the dam the sides 
of the river show two terraces, one of them 10 feet above the level of the water in 
June and the other 30 feet above that level. The banks of both terraces appear 
very young and freshly cut, as indeed they ought, since the lower is merely the 
border of the channel and the upper is occasionally undercut by the river when an 
unusually high flood causes the stream to overflow. It is interesting to note that 
the channel seems to be growing deeper at an appreciable rate. The dam is located 
just below the divergence of an old river channel which was abandoned something 
over a hundred years ago, and into which the new dam, completed about 1895, now 
