32 BULLETIN 61, U. S. DEPARTMENT OF AGEICT7LTT7BE. 
of the equation is the only one which admits of approximate quantitative statement, 
and figures for this have already been given. 1 
Of the ions, sodium and potassium are of most interest. These constitute 19.4 
per cent of the saline material. Potassium may be taken as 20 per cent of the com- 
bined weight or sodium and potassium. Applying these proportions to the 3,061,138 
tons of salines for the four basins gives 593,860 tons of sodium and potassium, and 
IIS. 772 tons of potassium as the annual :: crop" for approximately 95,000 square miles 
of the basin. 
The figures given in the preceding represent the rate of accumulation under present 
conditions. The humid conditions of the Quaternary must have produced a much 
greater rate of accumulation than at present. The greater area of lake surface during 
Quaternary times would give less land surface for chemical denudation. For the 
Lahontan and Bonneville Basins it has been shown that for one unit of lake area there 
were 3.5 units of basin area. For the 95,000 square miles under consideration this 
ratio would give 74.027 square miles of land and 20,973 square miles of lake surface. 
If we assume that the rate of accumulation equaled the present rate for the Tuolumne 
Biver watershed, the above area of land surface would yield a "crop" of 13,650,000 
tons per annum, or about four times the present rate of accumulation. While these 
results are no doubt crude, they at least give us some idea of the enormous amounts 
of salines that must have been discharged by the rivers of Quaternary times into the 
Quaternary lakes. 
SALINE DEPOSITS. 
To avoid repetition, this subject is presented under the following heads: Nitrates; 
Borates: Alum: Al unite: Crusts and Efflorescences; Playa Deposits: Deposits Besult- 
ing from Desiccation of Lakes: Buried Deposits of Salines; Salines in Present Lakes; 
CalcareDUs Deposits about the Shores of Present Lakes; Potash-rich Minerals; and 
Gypsum. 
NITRATES. 
Gale 2 has summarized the occurrence of nitrates in the Great Basin region. From 
hi- work I give below some of the principal facts. 
Nitrates have been reported in Utah, in the -vicinity of Marysvale, Monroe, and 
Greenwich Canyon, and Grass Valley: in Nevada, in the vicinity of Lovelock, in north- 
western Washoe County near Leadville, and in the canyons bordering the west side 
of Railroad Valley: in California, in the vicinity of the Calico Mountains, in the 
region northeast of Salton, along the Amargosa River near Tecopa, and in the vicinity 
of Death Valley, Searles Lake, and Danby Lake. The compounds reported are 
potassium, sodium, magnesium, and calcium nitrates. Potassium nitrate is the com- 
pound most often found. The deposits are of three types — cave, playa, and as efflo- 
rescences. M 3f : the Nevada deposits are of the cave type. They occur as veins, 
stalactites, and crusts in deposits protected from the action of surface waters. In 
playas. the nitrates are mixed with other salines. Occasional efflorescences of nitrates 
are found. The deposit occurring south of Tecopa, Cal., and along the Amargosa 
is :■: this type. The nitrates of the basin region are either leached from the soils or 
originate from the decaying organic matter accumulating in the caves. Gale is of the 
opinion that probably a majority of the nitrate deposits result from the decomposition 
of bat or similar guano in caves, or crevices in the rocks. 
Nitrates have been reported in small amounts in river and lake waters. Van 
kle and Eaton report the nitrate radical in 18 river waters out of some 30 examined 
in California. The average content for the Owens River is 1.7 parts per million. This 
is equivalent to 0.5 per cent of the anhydrous residue. A more extended search for 
this radical would, no doubt, show it present in small amounts in most of the river 
- : the basin. The origin of nitrate in river water is due to the leaching action 
of rain water on soils. Owens Lake contains 94S parts per million of nitrate radical. 3 
J. G. Smith reports traces of nitrates in all the waters from the southern Oregon lakes 
which he examined. I have no doubt that this radical, in small amounts, 'could be 
found in other basin lakes. In the analysis of the soluble material of basin soils 
1 The mean annual run-off for the basin resion was approximatelv determined to be 1.06 inches of rainfall 
If we assume the saline content to be 62.7 parts per 100,000 (the mean saline content of California rivers for 
semiarid conditions), the saline content in the run-off from 1 square mile is 96.2-51 pounds. This approxi- 
:he figure obtained for the Bonneville basin. On this basis the annual crop of salines for the whole 
basin would be 10,103,200 tons. The playa, silt and lake area is about 30 per cent of the basin area or 63,000 
square miles. The concentration of the annual crop of salines on this area would give 164 tons per square 
mile or a surface crust 0.0012 of an inch thick. 
1 Bui. No. 523. O. S 
1 W ater-Supply Paper No. 237, p. 122. 
