Lake Otero, X. Mex.—Heniek. 183 
Other portions of the valleys become incrusted to the depth of 
several inches with alkaline salts which rise to the surface as 
an efflorescence and give the appearance of drifted snow. The 
dry surface material of the deserts is sometimes blown about 
by the winds, saturating the air, or is caught up by whirl- 
winds and carried to a great hight, forming great hollow 
columns of dust. These swaying and bending columns, often 
two or three thousand feet high, rising from the plains like 
pillars of smoke, arc a characteristic feature." 
The above might almost have been written of the Otero 
basin, which, nevertheless, has peculiar features of its own. 
Prominent among these are the great dunes of gypsum sand 
occupying fully 300 square miles lying immediately east of 
the largest playas. These "white sand=" have no counterpart 
elsewhere and have frequently been described.* It must not 
be supposed that the area of the white sands is absolutely bar- 
ren. On the contrary, it forms the only part of the basin 
which supports a thrifty growth of vegetation. This con- 
sists of occasional clumps of cottonwood trees and clusters 
of bushes of various species as well as of Artemisia and 
grasses. There are even small flats covered with Grama 
grass forming excellent feed. The suneriority of the vegeta- 
tion over other part^ of the basin is chiefly to be attributed to 
the hygroscopic nature of the gypsum. We found, for ex- 
ample, in the midst of a very dry time when the surface of the 
dunes was so hot that one could with difficulty endure the 
beat upon the bare hand, that a few inches below the surface 
there was a layer of damp sand several inches thick. Below 
this layer the sand was perfectly drv. Even in very hot 
weather this area is very cool at night nnd this is the result of 
precipitation, evaporation and reprecipitation upon the sands. 
Experiments made at the Agricultural College of Las Cruces 
show that the gf}^psuni is of value in increasing the growth 
of wheat and other crops upon soil with which it is mixed. 
This appears to be wholly due to the hygroscopic action of 
the gypsum. It is probable that, when properly understood 
and utilized, this property will be made greatly to benefit ag- 
riculture m the arid belt. A sufficient covering or admixture 
• Cf. Bui. Univ. New. Mex., vol. ii. 
