68 BULLETIN" 61, TJ. S. DEPARTMENT OF AGRICULTURE. 
Group II. — Basins in which there are no evidences of Quaternary lakes. 
Square miles. 
A. Death Valley, includes Amargosa drainage and basin 23, 160 
B. Silver Peak 550 
Rhodes Marsh 540 
Teels 320 
All other basins in which the playa contains notable quantities of brine 
and in which the brines are close to, or at, the surface. 
C. All other desert basins and playas not included in the above groups. 
The order given in each main group is the order of relative importance. In each 
subgroup the order given is the order of area! importance. Groups A and B of each 
main group are believed to be the most favorable areas for exploration work. Group 
II is of very much less importance than Group I. 
Of the basins enumerated above, Searles is the only one in which the investigation 
has shown sufficient concentration of potassium salts in the residual brines to be of 
probable commercial importance. The salines associated with the potassium salts and 
the possibility of producing several products predict success in the exploitation of this 
area. The chemical problem of separating the several salines is a difficult one, and 
upon its solution hinges the success of the enterprise. The presence of brines of mod- 
erate concentration is shown in Death Valley and Silver Peak. 1 It is a matter of 
some doubt whether these brines can be worked. The investigation of the Carson 
Sink, Railroad Valley, and Columbus Marsh is inconclusive. Until the possibilities 
of the areas considered most favorable have been exhaustively studied, it is inadvisable 
to attempt exploration of the other areas. 
1 The potassium in the surface brines of the smooth salt area of Death Valley is equivalent to 1.72 per cent 
potassium chloride; in the brines from the Survey's bores in Death Valley it is equivalent to 0.94 per cent 
and in the brines of Silver Peak Marsh 1.50 per cent. But comparatively little concentration would be 
required in these brines to produce a brine of the same content of potassium chloride as the Searles brine. 
The Death Valley surface brine would have to be concentrated one-half, the deeper brines one-fourth, and 
the Silver Peak brine somewhat less than one-half. In Death Valley the summer evaporation rate for a 
brine is said to be from 24 to 30 inches per month. The cost of evaporating a brine under such conditions 
would be almost nothing. The amount of brine available for pumping and the practicability of construct- 
ing vats upon the smooth salt area would have to be determined by detailed examination and experimenta- 
tion. In my opinion the experiment of producing potassium salts by evaporating the Death Valley brine 
is well worth carrying out, presupposing that the detailed examination shows a sufficient quantity of 
brine. 
