340 



Journal of Agricultural Research 



Vol.X, No. 7 



This shale, so highly impregnated with the sulphates, chlorids, and 

 nitrates of calcium, magnesium, sodium, and potassium, is the sole 

 material out of which many of the soils of the area are made. In certain 

 small areas the sandstone, also rich in soluble salts, contributes to the 

 soil formation, while in still other small areas the river wash from other 

 geological horizons contribute to the soil formation. But the major 

 portion of the land of the area investigated is derived from the Mancos 

 shale of Cretaceous origin. The irrigating canals of the region, run by 

 gravity, are diverted from the rivers high up on the stream and, as a 

 result, cut through the shale strata in many places. The shale, broadly 

 speaking, is nearly horizontal, and the strata lie like the leaves of a book. 

 The irrigation canal cuts this strata in the higher-lying ground, and, as a 

 result, the seepage water from the canal follows the folds of the shale to 

 the point of outcrop where the soluble salts, concentrated from the 

 entire shale area covered, are deposited on evaporation of the water. 

 The result is a good crop of alkali or an alkali bog. In certain isolated 

 basins the problem is intensified by the rise of the ground water, with 

 its solvent action upon the undecomposed shale. This is the sole origin 

 of the alkali of the observed area. 



SOLUBLE SALTS IN THE CRETACEOUS ASH 



As already reported, there appears on the surface of the slight decom- 

 posed shale a mealy mass of white-gray material which has a burnt-ash- 

 like appearance. The material is crystalline when examined with a hand 

 lens. On placing under the microscope for examination, it largely dis- 

 solves on the addition of water. Eight representative samples of this 

 were collected and analyzed. The results are recorded in Table III. 



Field No. 



133- • 

 77... 

 124.. 

 260. . 

 276. . 

 134.- 

 145- • 

 122a. 



Average . 



Table III. — Soluble salts in Cretaceous ash 

 [Results expressed as pounds per 2,000,000 of material] 



Location of sample. 



Emery, Utah 



Grand Junction, Colo, 



Emery, Utah 



Thompson, Utah 



Vernal, Utah 



Emery, Utah 



do 



do 



Cretaceous. 



Calcium 



(Ca). 



11,308 



12, 192 



722 



19, 808 



7, 377 

 Trace. 



6,576 

 1,764 



7,468 



Mag- 

 nesium 



(Mg). 



3.552 

 10, 206 



Trace. 



978 



3, 600 



559 



4, 662 

 Trace . 



2,807 



Carbonic 

 acid 

 (CO3). 



5, 200 



240 

 I, 040 



840 



640 

 9, 600 



880 

 I, 240 



795 



Sulphuric 

 acid 

 (SO3). 



129, 680 

 255,200 



44, 568 

 114, 600 

 127, 960 



14, 416 

 102, 800 



7 1 , 408 



93> 193 



Chlorin 



(Cl). 



5,389 



1,418 



900 



852 



Trace. 



I, 276 



709 



I, 400 



This ash material found on the surface of the shale represent*? the 

 accumulation of salts due to the solvent leaching and evaporation of 

 rain or ground water. 



