GEOLOGICAL HISTORY OF NORTHEASTERN PERSIA. 235 
deep and so narrow that there is only room for a single horseman to pass between 
the walls. Northeast of Radkan his party "plunged into a deep and narrow gorge 
that cut straight into the heart of the rock wall as though some Titan's axe had 
slashed a savage gash in the solid stone. Its walls were absolutely perpendicular 
and shaped in parts by the stonns of centuries into windy buttresses and towers, 
while at the bottom brawled a stream which had hollowed pools in the rocks, and 
up and across the bed of which it was with difficult}- that our horses could be 
persuaded to climb. The formation and scener}' of this magnificent gorge, whose 
walls are in receding terraces, are a precise reproduction on a miniature scale of the 
unequaled canyon of the Colorado in Utah." This comparison is ver\- appropriate, 
for just as the horizontal strata of the Colorado plateau were uplifted at the time 
of the formation of the Grand Wash fault and have for a short time been exposed 
to dissection, so, at a correspondingly recent date, the slightly tilted strata of Kopet 
Dagh were uplifted at the time of the formation of the Meshed fault and are now in 
process of rapid dissection. 
The drainage of Kopet Dagh appears complex. In part, as at Anau, it is 
clearly consequent, depending entirely on the attitude assumed by the moimtains 
in consequence of recent earth movements. The streams follow relatively straight 
courses in steep-sided young gorges, and the crests of the ridges form the main 
divides. Oftener, however, as Curzon (I, p. 144) points out, the streams flow along 
the main valleys parallel to the axis of the mountains for a certain distance, and 
then, without warning, turn suddenly at right angles and pierce the mountain ranges 
at almost their highest points, cutting gorges of almost incredible depth and grandeur. 
"The base of these defiles seldom admits more than a torrent bed blocked with 
enormous bowlders, and the walls are frequently vertical to a height of from 500 
to 1,000 feet. The main divides are seldom the highest ranges or crests. The 
streams start on one side of the main ranges, and after running parallel to them 
for a while, break through to the other side, and perhaps run in an opposite 
direction for a time." Apparently, though the data are ver>' scanty, the drainage 
of Kopet Dagh was originally like that of the Appalachians, subsequent for the 
most part, but with antecedent remnants of a former consequent drainage. This 
has been further complicated by the recent uplifts, which in some places have 
caused the previous drainage channels to become more deeply intrenched, while 
elsewhere the}' have given rise to a new consequent drainage. 
THE MESHED BASIN. 
The so-called Meshed Valley south of Kopet Dagh is in realit}- a narrow, 
cigar-shaped basin or depression, 10 or 15 miles wide, and at least 150 miles long 
from northwest to southeast. On the north it is bounded by the Meshed fault ; 
on the south it seems to be separated from the mountains of Binalud by a simple 
flexure. At Kuchan, in the western half of the basin, its floor is arched where the 
Meshed fault becomes a flexure. As a result, the basin is occupied b\- two streams, 
probably consequent, one of which, the Atrek, flows northwest to the Caspian Sea, 
while the other, the Meshed River, or Keshef Rud, flows southeast to the Heri Rud ; 
