POTASH SALTS AND OTHER SALINES IN THE GREAT BASIN REGION. 49 
Through the kindness of Dennis Searles, E. E. Free obtained the samples from a 
bore put down over 600 feet in the area northwest of the central salt area and near 
the road leading from the plant of the California Trona Co. southeast of the salt area. 
The exact location of this deep bore is not known. The series of samples is not com- 
plete, and the notes accompanying them are also somewhat incomplete. The results 
of analyses upon these samples are given in the accompanying tables. Table XXV 
(Appendix) gives the total sodium and potassium, soluble sodium and potassium, 
and insoluble sodium and potassium. Table XXVI (Appendix) gives the ratios of 
soluble sodium to potassium, of insoluble sodium to potassium, and of total sodium to 
potassium. Tables XXVII (Appendix) and XXVIII (Appendix) show respectively 
the percentage composition of the samples, and of the water-soluble material con- 
tained in the samples. Accompanying is a brief description of a petrographic study 
(Table XXX, Appendix) upon the samples of the deep bore by J. C. Jones. It is 
unfortunate that the record is incomplete, but incomplete as it is, the results of our 
examinations are of sufficient interest to warrant presentation. 
Before discussing the foregoing data, it is necessary to establish certain criteria 
by which we may determine the nature of the events which took place during the 
history of this lake. 
The progressive or fractional crystallization of brines and salt solutions has been 
thoroughly discussed by Turrentine. 1 On account of the similarity of conditions, I 
have deemed it best to take the results which T. M. Chatard obtained in his experi- 
ments upon the waters of Owens and Mono Lakes. These results are shown graphically , 
in figure 6. 2 The waters from both lakes are similar in composition. Mono Lake 
water has a slightly higher percentage of sodium sulphate than Owens. The water 
in both cases contains carbonates, bicarbonates, sulphates, chlorides, and borates; 
also sodium, potassium, and minor amounts of silica, calcium, magnesium, alumina, 
and ferric oxide. The temperature conditions in the evaporations range from 18.3° C. 
to 37.8° C. The two sets of experiments indicate similar results. The following are 
the criteria from these experiments: 
1. At initial stages of evaporation calcium carbonate, mixed with more or less 
ferric oxide, would be precipitated. 
2. Saturation would be indicated by a crystalline deposit in which carbonates 
would predominate. Sulphates would be least and chlorides would be present in 
moderate amount only. Potassium chloride would be less than 1 per cent of the 
saline deposit. The ratio between sodium carbonate and bicarbonate in the deposited 
salines would approach unitv. 
3. Succeeding stages would be marked by decreasing amounts of carbonates and 
increasing amounts of sulphates and chlorides. The ratio between sodium carbonate 
and bicarbonate would rapidly increase. At an intermediate stage sulphates would 
reach a maximum. Sodium chloride would remain in about the same proportion, or 
would be slightly increased. 
4. Approach to final desiccation would be indicated by the separation of a large 
proportion of sodium chloride and a small increase in the proportion of potassium 
chloride. 
5. Final desiccation would yield relatively small amounts of sulphates and a larger 
proportion of chlorides and carbonates. Some borates would be present. The sodium- 
carbonate and bicarbonate ratio would reach a maximum value, and relatively large 
proportions of potassium salts would characterize this state. 
Four terms may be designated to indicate the progressive stages, and in their natural 
order are: 
(1) The trona period — sodium carbonate and bicarbonate in about equal amounts 
preponderate; 
(2) The sulphate period — separation of sodium sulphate; 
(3) The sodium chloride period — maximum proportions of sodium chloride; 
(4) The complete desiccation period — maximum percentage of potassium chloride 
and presence of borates. 
In the case of the uninterrupted desiccation of a saline lake the successive stages 
mentioned above would grade insensibly one into the other. The actual case, would 
be further complicated by temperature variations, seasonal and periodical, by inter- 
ruptions caused by the dilution of lake waters, by rainfall and stream discharge, and 
by silt, mud, and seolian deposition. Wind and wave action would tend to thicken 
the shore deposits. The thinning out of the lake waters at the margin would set up 
there more favorable conditions for crystallization than in the deeper portions. In 
1 The Occurrence of Potassium Salts in the Salines of the United States. Bui. No. 94, Bureau of Soils. 
U.S. Dept. of Agr. 
2 Data for this figure were taken from Bui. No. 60, U. S. Geol. Survey, pp. 59-65. 
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