338 Journal of Agricultural Research voi.x, no. 7 



so vital in the sandy soils of the area, but the fact that the salts in the 



sandstone are largely the salts of calcium and magnesium is one important 



reason. 



SOLUBLE SALTS IN CRETACEOUS SHALE 



3/ if ty_seven samples of Cretaceous shale were collected and analyzed for 

 soluble salts. The icaults are recorded in Table II as pounds per 2,000,000 

 of shale. 



As an average, the Cretaceous shale is much richer in sulphates and 

 chlorids than is the sandstone. Again, the sulphates are the predomi- 

 nating salts. There is little less calcium in the shale than in the sand- 

 stone, while the latter contains over twice as much magnesium as the 

 former. The increase in sulphates and chlorids is due to the presence 

 of the salts of sodium. 



As an average, there are present in this shale 993 pounds of calcium 

 bicarbonate, 15,738 pounds of gypsum, or calcium sulphate, 10,780 

 pounds of magnesium sulphate, 13,036 pounds of sodium sulphate, 

 1,148 pounds of sodium chlorid, and 2,079 pounds of sodium nitrate — 

 that is, at least 2.19 per cent of this shale material consist of water- 

 soluble salts. Some samples are markedly rich in the soluble salts, while 

 others are not so rich. But all the samples contain some soluble salts, 

 and, unlike the sandstone, the shale contains large quantities of the more 

 harmful sulphate and chlorid of sodium. 



There is, of course, a marked variation in the composition of the 

 soluble salts. In some samples there is no soluble calcium, while in 

 others there is no soluble magnesium. In one sample there are no 

 soluble carbonates, but the solution is really acid. Many samples con- 

 tain no chlorin, or at least only traces of this acid ion. 



There is no definite ratio between the various acidic or basic elements 

 in the several samples. The sample which is richest in chlorids. No. 84 

 from Green River, contains only moderate amounts of sulphates. It is 

 much richer in calcium than the average, but is not the richest in calcium. 

 It contains less than the average amount of magnesium and nearly the 

 average amount of carbonic acid. It contains nearly the maximum 

 amount of nitric nitrogen, yet there are other samples of shale which are 

 richer in nitric nitrogen but which contain only traces of chlorin. The 

 sample which is richest in sulphate. No. 8126 from Emery, Utah, con- 

 tains only traces of chlorin, no carbonic acid, moderate amounts of 

 calcium and magnesium. The 12 per cent of soluble sulphates consist 

 largely of the compounds of magnesium and sodium. This sample is a 

 coal-bearing shale, the definite strata of coal being seen with the naked 

 eye. It was obtained just below an economic supply of undeveloped 

 coal near Emery, Utah. Its aqueous solution was highly colored a dark 

 brown. This lack of any definite ratio is exactly what one would expect. 

 The salts were deposited from the saline water of the old inland seas, 

 and isolated playas would undoubtedly become more concentrated in 

 some salts than others 



