CHAPTER X. 
UP THE ALAI VALLEY 
B efore I proceed with my itinerary, I should like 
to say a few words about the Alai' valley, the huge 
trough-like depression which separates the Alai chain from 
the Pamir plateau. Bounded on the north by the Alai 
Mountains, and on the south by the Trans- Alai, it is 
terminated at its eastern extremity by the massive 
mountain - knot of Mus-tagh-tau. Thence it stretches 
seventy - five miles westwards, and is continued in the 
valley of Kara-teghin. Its breadth varies from three to 
twelve miles ; the altitude sinks from 10,500 feet in the 
east to 8200 feet at Daraut-kurgan in the west. It is 
drained by the Kizil-su, which traverses it throughout its 
entire length, gathering up on the way the rainfall of the 
surrounding mountains. After quitting the Ala'i valley, 
the river enters the valley of Kara-teghin, winds through 
it under the name of the Surkhab, and finally joins the 
Amu-daria, bearing a third name, the W akhsh, at the point 
of confluence. The volume of the Kizil-su amounted to 
780 cubic feet in the second at Daraut-kurgan. Add to 
this the volume of 175 cubic feet in the second contributed 
by its affluent, the Kara-su, and we get a total volume of 
eighty-two and a half million cubic feet in the twenty-four 
hours. The volume is greatest in the middle of summer, 
when the snows melt at the fastest rate. Indeed for about 
six weeks at midsummer the flood is so powerful that it is 
impossible to ford the river at Daraut-kurgan. During 
that time all communication between the auls on the 
opposite banks is completely interrupted. 
The volume of the stream is very much greater during 
the night than during the daytime. This is owing to the 
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