RECONNAISSANCE IN TURKESTAN 275 



nomads. Water can be distributed on about 2 per cent of the entire 

 area, on land free from drifted sands. Along the base of the south- 

 ern mountains stretches a chain of narrow oases at the mouths of 

 the mountain vallej^s ; there are other very narrow strips along the 

 larger river courses, and more extensive areas inclosed between the 

 projecting spurs of the eastern mountains ; all the rest of the basin 

 has become the prey of the moving sands, which are still very slowly 

 but surely invading the oases. The boundary is sharply defined ; 

 within it is high cultivation ; beyond is a sea of waves of sand. 



As they extend eastward the southern mountains increase in 

 height, till both they and the great spurs of the Tienshan — giant 

 snow and ice covered crests and peaks — dominate the oases which 

 are the offspring of their waters. It is on this mountain snow and 

 ice that the life of the whole region is and has been from a remote 

 period absolutely dependent. 



This life is also limited by another factor — itself a result of the 

 desiccation — the moving sands. For, other things remaining equal, 

 while the shrinkage of the water areas can continue only till equilib- 

 rium between supply and evaporation is reached, and while there 

 might be also cyclical periods of revivifying afflux, these compensa- 

 tions are offset in the oases by the steadily overwhelming progress 

 of the sands. 



The progressive desiccation of Turkestan is shown by direct 

 observations during the past century, by artificial landmarks, by 

 historical statements, and by natural records. The Aibughir gulf 

 of the Aral was 133 kilometers long and 3,500 square kilometers in 

 area in 1842, and dry land in 1872. 



The volume of the Sirdaria has diminished greatly, as shown by 

 the remains of old irrigating canals along its whole lower course, 

 which are now too high to receive water. The statements of Ara- 

 bian writers show that, within recent historical times, there was a 

 far more numerous population than the country could support now, 

 when all available water is utilized. Old water level lines occur at 

 various heights up to 225 feet above the Aral. 



The progress is not uniform, but is broken by periods of tempo- 

 rarily increased precipitation. Dorandt measured in 1874-75 a fall 

 of 70 millimeters in the year in the Aral sea. Schultz, in compar- 

 ing his surveys of 1880 with earlier maps, found a lowering of the 

 level of 38 centimeters in nine years. On the other hand, Berg in 

 1901, comparing the gage established by Tillo, found the level 121 



