PHYSIOGRAPHIC OBSERVATIONS. 
131 
distance. In tlie distance, a silver\' sheet of water reflects and dances on the plain. 
For a moment there seem to be men and animals moving on the shore, but then 
the lake slides away into space, the men and animals disappear, and there, instead, 
is the mocking plain. 
A far-off dust colunni appears on the horizon. At first it seems motionless, 
but soon there is a visible movement as it approaches, growing denser and taller, 
and turning, it rapidly crosses the steppe with an irregular motion. It may fade 
away in the distance ; it may disappear suddenly in some unexpected place. These 
dust storms tell a storj'. During the warm hours of the day there is nearly always 
one, often there are two or more in sight. The desert surface here shows a 
Fig. 90. — Deflated bowlder of granite. 
Fig. 91. — Deflated bowlder o( granite, hollowed side 
facing east. Taken at 10.30 a. m. 
Fig. 92. — A talus-shrouded mass of crystalline limestone. 
Fig. 93. - A glacial bowlder of crystalline limestone cracking 
from the changes of temperature. 
remarkable lack of loose, fine material. But tlie inclosing mountains are largely 
made up of rotten g^-psum and limestone with earthy surface, from which great 
quantities of fine stuff are brought down during cloudbursts and left on the fans, 
always to be carried away by the winds and deposited elsewhere ; probably, according 
to Richthofen's theor}-, as loess in some neighboring zone of vegetation. 
Kara Kul is a lake of bitter salt water. Its sloping shores are white with salt 
accunuilated into low ridges where the brine from each wave-wetting has dried out 
after the recession. Behind some of these natural dams there are lagoons of brine 
collected from the overflow of larger waves, and thus, in places, extending the salt 
belt 100 feet or more from the shore. I could find no shells and saw no fishes. 
