48 EXPLORATIONS IN TURKESTAN. 
floor, as one goes iip-stream, is evidently snggesti\e of uplift. From the highest 
hill, a nionoclinal ridge of brownish sandstones, 835 feet over Firuza, we could see 
the modern flood plain, about a quarter mile wide, etched below the dissected gravel 
bench, which must in its prime have been from half a mile to a mile in width. 
It may be noted that about 10 miles southeast of the gorge the monocline of the 
outer(Markou) limestone range narrows, becomes lower, and ends, and further on the 
flanks of the main anticline descend to the plains. Northwest of the gorge the 
front monocline rapidly increases in height for several miles, and its southwest slope 
exposes great, bare sheets of heav>-, steep-dipping limestones. This range is believed 
to be faulted iip along its front, because the strata in the neighborhood of the gorge 
either dip southwest into the range or lie nearly horizontal. The scarp of the 
range, much ravined, looks directly upon the open plains. General subaerial erosion 
can not have removed the forward extension of the strata to any great extent, for 
erosion has as yet only succeeded in battering back somewhat the steep walls of the 
o-orge ; hence the absence of the strata in front of the range can only be explained 
by faulting. It should be noted that we caught a glimpse, while we were still on 
the plains, of what .seemed to be steep northea.st dips in the strata of the front scarp 
a few miles northwest of the gorge ; hence the faulted monocline may there assmne 
the character of a toin anticline. 
The treeless hills of the Firuza syncline revealed their structure most clearly. 
The dip of the .strata was distinctly steeper on the northeast than on the southwest 
side ; the lower beds were grav .shales, on which subsequent vallejs were opened ; 
the upper ones brownish sandstones, which rose in ridges. The total thickness was 
probabl)' i , 500 or 2,000 feet. The limestone flanks of the main range exhibited many 
smooth stnictural slopes of moderate dip, green with vegetation, and deeply gashed 
by con.sequent streams. The upper Firuza gorge was seen as a deep chasm, which 
we followed through the next day. Its stream was only 10 or 15 feet wide, but 
about a month after our visit we heard that it rose in a destructive flood and swept 
through the village, doing much damage to the houses and gardens. 
The upper gorge is as fine an example of a transverse through-going defile as 
I have seen. It is 10 miles long, and in that distance the valley floor rises about 
2,500 feet. For the first half of the way there is a narrow flood plain between pre- 
cipitous walls, hundreds of feet in height ; then after passing a strong fault, 
expressed by local defonnation and a change in the character of the limestones, the 
walls are less steep and the floor is more encroached upon b}- talus and fans. The 
mountain tops, 4,000 or 5,000 feet above the stream, could not be seen. As the 
wagon road ended at Firuza, our further progress was on horseback with pack train, 
and thus we crossed the boundary into Persia. We met a few men in the gorge 
driving donkeys laden with fagots, but came upon no habitations till we reached 
the open longitudinal consequent valle>- where the little Persian ^•illage of Serani 
is situated amid green irrigated fields, at an altitude of about 4,700 feet. The irri- 
gating stream is chiefly supplied from a large spring at the base of the limestone 
range on the soiithwest side of the valley. The stream is used to drive a primitive 
mill near its source. 
