POTASH SALTS AND OTHER SALINES IN THE GREAT BASIN REGION. 
27 
Depth of accumulations of soluble salts in soils. 
-inch rainfall, Imperial 
ley, Cal. 
Val- 
8-inch rainfall, 
Fresno district. 
12-inch rainfall, 
Yellowstone 
Park. 
15-inch rainfall, 
Ventura County, 
Cal. 
20-inch rainfall, 
Grand Falls, 
N. Dak. 
In virgin soils greater part of 
soluble salts at a depth of 18 
inches. 1 
Sandy loams 3 to 
4 feet; coarse 
sands 4 to 8 
feet.i 
Heavy soils 4 to 
6 feet; sandy 
soils 7 to 11 
feet. 2 
Bulk of soluble Greater part of 
salts at 5 feet. 1 soluble salts 
below 3 feet. 
1 Bui. No. 35, Bureau of Soils, p. 15. 
2 Bui. No. 14, Bureau of Soils, p. 27. 
Two important actions take place in the movement of saline material in soils. 
Rainfall penetrates the surface soil and percolates down to certain depths. In its 
passage downward it dissolves a portion of whatever soluble salts may be present and 
thus leaches the material at the immediate surface. The extent to which this leach- 
ing would take place would be determined by the proportion of gravity water to water 
of capillarity and the penetration of the water. This is determined largely by the 
texture of the soil. With a porous soil this leaching action would be especially notice- 
able. In the leaching of a soil in the manner described above, it is evident that the 
more soluble constituents would be first dissolved and carried to the greatest depths. 
Underground water soon reaches a position of equilibrium which may be within the 
permanent ground-water level or within the zone close to the surface. Capillarity 
begins to act. The ground water moves toward the point at which evaporation takes 
place. It should be noted that when this water reaches its equilibrium position it 
has dissolved a large amount of salt. When the solution is returned by capillarity 
these salts are carried with it and deposited at the point where evaporation takes place. 
Capillarity may not return these salts to the surface, for evaporation may take place 
below the immediate surface, and the capillary water column may terminate at vary- 
ing distances from the surface. The height to which the water is raised by capillarity 
would determine the position of accumulated salts. It has been shown in another 
place that where ground waters are deeper than 10 feet from the surface little or no 
evaporation from them takes place. This would indicate that ground waters at depths 
greater than 10 feet could not be concentrated by evaporation, and consequently there 
would be little or no opportunity for the separation of salines under such conditions. 
NATURE OF SALINES IN SOILS. 
Calcium, magnesium, sodium, and potassium are the bases almost invariably present. 
Sodium in almost every instance is the dominating base, while calcium and magnesium 
are usually the smallest in amount. Potassium is much less than sodium. In the 
Fallon soils sodium is 12.6 times potassium, while in the Utah soils it is 5.6 times. The 
acid radicals of chlorine, sulphur, carbon dioxide, nitrogen, and phosphorus are inva- 
riably present. Chlorides and sulphates usually predominate, although in some soils 
carbonates and bicarbonates are in greater abundance. The Fallon soils contain sul- 
phates in greatest amount, while in the Utah soils chlorides are in greatest amount. 
Bicarbonates are usually present in greater amounts than carbonates. Phosphates 
and nitrates are present in most cases in traces, although in some exceptional cases 
nitrates may be present in appreciable amounts. Two Fallon soils showed over 2 per 
cent nitrate in the total solids. The basin soils would present many variations from 
the examples given. Borates, for instance, are common in many play as. 
COLLECTION OF SALINES BY SURFACE WATERS. 
RIVER AND LAKE WATERS. 
Rivers being the main collecting agents for gathering salines from a given area and 
transferring them to the lakes and lake basins, the content and nature of the salines 
as well as the amount collected can be determined from the analyses of the river 
waters. It should be noted that the rivers receive a certain proportion of seepage 
water and consequently the chemical analysis reflects not only the nature of the salts 
collected from the weathering zone, but also the salts received from underground 
waters. It is to be regretted that analyses of composite samples taken from basin 
rivers over long intervals of time are not available. What analyses are given represent 
single samples. The results must be used with caution. 
The lake waters represent the saline accumulations during present times. It should 
be noted that certain compounds are precipitating out continuously and consequently 
the composition of the waters represents an approach to equilibrium conditions for 
the particular time. Variation in climatic conditions results in the raising and lower- 
ing of lake levels. The fluctuation in lake levels, together with the continual acces- 
