234 THE BASIN OF EASTERN PERSIA AND SISTAN. 
average breadth of 40 or 50 miles, extends for 350 miles to the Afghan frontier. 
My own knowledge of the range is based on three caravan jonnieys — one into tlie 
high mountains south of Askhabad ; anotlier around the eastern end of the range 
from Uushak, where the railroad turns away from the mountains, to Scrakhs and 
up the Heri Rud ; and a third from Meshed, via Kuchan, to Askhabad. 
Kopet Dagh appears to be a fairly mature mountain mass which has recently 
been faulted and strongly uplifted, and thus rejuvenated. The highest portion, 
near Askhabad, has been described by Professor Davis (ante, p. 46). Farther to 
the east the mountains present the same flat-topped appearance, with young \alleys 
cut sharply into structural slopes which must have assumed their present smooth 
character during Tertiary times, when the mountains stood lower. This is well 
illustrated in the back slope of the Gaoudan block, which is without difficulty 
reached from Anau, 6 miles east of Askhabad. The faulted face of this block, 
as seen from the Meshed road, is a precipitous escarpment of naked rock. The 
back slope, on the contrary, is a long, smooth descent, covered with soil, and closely 
corresponding to the dip of the limestone strata. In this are cut five or six black 
gashes, the parallel gorges of young consequent streams which have cut .so deeply 
into the uplifted mountain mass that their sides appear from a distance to be perpen- 
dicular. East of Dushak, where the railroad leaves the ba.se of the mountains, the 
strata of Kopet Dagh become softer and are more thoroughly dissected, but the 
hilltops still retain a flat aspect and the vallejs are steep-sided and narrow. 
On the southern side of the mountains there is clearer evidence of recent 
uplift. Looking northward from Meshed toward Kopet Dagh, the plain is bounded 
by a line of steep bluffs, which rise a thousand feet in one or two great jumps, and 
continue northwestward scores of miles. They are cut in strata, apparently Cretaceous 
limestone, which lie nearly horizontal, with a slight roll from northwest to .soiith- 
east. The steepness and straightness of the mountain front, its slight dissection, 
and the absence of a stream competent to produce such effects suggest that the 
escarpment is the result of recent faulting by which the mountains were uplifted 
and subjected to renewed dissection. Between the top of the bluffs and the remark- 
ably smooth crest of the range the uplands are rounded and mature in form. These 
same features continue far to the northwest, but in the neighborhood of Kuchan 
the bluflfs decrease in height and the escarpment comes to an end. Apparentl}' the 
fault gradually decreases in amplitude, and near Kuchan, after a course of about a 
hundred miles, is transformed into a simple fle.xure where the strata of the moun- 
tains dip south westward and pass under the plain. In the neighborhood of the 
fle.xure the aspect of the mountains is more mature than in the regions which have 
been uplifted by faulting. This g^eat displacement along the southern border of 
the mountains is parallel to the smaller displacements on the north side near 
Askhabad and seems to be of about the same age. 
The }'outliful character of the vallej-s in the uplifted block of Kopet Dagh 
agrees with the steep fault face in indicating that the uplift is of ver>' recent date. 
For instance, in the mountains north and northwest of Meshed, Curzon (I, pp. 122, 
123, 141) describes frequent instances of magnificent gorges from 1,000 to 1,500 feet 
