i64 The American Geologist. September, ioo4 
falls into the Rio Grande. This little stream has carved out a 
remarkable vallev. It is an illustration of how wonderfully 
effective is even a small, often dry, rivulet in corrading the 
high plains. 
The bolson plains may be considered as sections of an 
upraised peneplain surface in its earliest infancy, at a stage 
in which they are as yet untouched by stream-action. They 
could not exist under present hypsometric conditions except in 
an arid region, which snow-fed perennial rivers do not tra- 
verse. The bolsons are only apparently lake-like basins. They 
have a marked slope in at least one direction, that of their major 
axis, as in the case of the Jornada del Muerto, where the 
slant is 20 feet to the mile and greater than the gradient of the 
parallel Rio Grande. Had the latter stream entered at Santa 
Fe the Estancia-Huerco or Estancia'-Jornanda line of bolsons 
instead of the line to the westward, a vast canyon would have 
occupied these basins. 
The bolson plains of central New Mexico hang high above 
the great channels of the Rio Pecos and Rio Grande on either 
side. Were the rainfall of the region sufficient to produce 
perennial streams these plains would be soon as deeply carved 
out as the great adjoining valleys of the rivers just men- 
tioned. 
Nczv Mexico School of Mines, July i, 1904. 
THE ALKALI DEPOSITS OF WYOMING. 
B}^ Thos. T. Read, Laramie, Wyoming. 
Scattered over the south central part of Wyoming are nu- 
merous undrained depressions containing large amounts of 
salts of sodium and magnesium, chiefly sulphates, which are 
locally known as soda lakes. Of these there are eight groups 
composed of from one to several lakrs varying from a few 
to several hundred acres in extent. In addition there are 
smaller lakes scattered in such profusion that no estimate of 
their number has ever been made. 
Two questions chiefly concern us. their origin and their 
uses. As to the latter, their great future value for the pro- 
duction of carbonate of soda and caustic soda is evident. ]Manv 
