AIR WATER SOILS. 



1027 



irrigated lands in the immediate vicinity of Billings, Montana. The 

 Yellowstone Valley at this point is about G miles wide and bordered on 

 either side by high bluffs — on the north the bluff is of sandstone and 

 on the south of blue shale. The sandstone is a gray siliceous stone 

 containing small but perceptible amounts of magnesium and sodium 

 sulphates, which are either dissolved and carried away by the water 

 which percolates through the rocks or accumulate in layers through- 

 out the rocks. Where evaporation has gone on for some time these salts 

 appear as white effloresce uces on the surface. 



"Underlying the sandstone and coming ont from under the sandstone bluff there 

 is a line blue shale or slate which extends to an unknown depth. In an attempt to 

 get artesian water at Billings a well was driven 900 ft. through this shale. No 

 deeper record than this has ever been made at this place. The shale rises up from 

 beneath the sandstone and forms the rough angular blue hills on the south side of 

 the valley. 



"The shale is penetrated with numerous fine cracks and joints running in all 

 directions, and these are rilled with fibrous gypsum. Many cavities also are found 

 filled with gypsum and calcium carbonate. Everywhere throughout the shale large 

 quantities of sodium and magnesium sulphates arc found, which appear as white 

 efflorescence where evaporation has taken place 



"As the rocks weather, a portion of the soluble salts is removed in the springs and 

 seepage waters, but the removal is not nearly so complete as is the case in the humid 

 portions of the United States, because the small raiufall renders the escape of all of 

 the excessive amounts of salts impossible. 



"The two types of rock give rise to two distinct types of soil in the valley — one 

 a' sandy soil, derived from the disintegration of the sandstone rock, giving a soil of 

 open texture, easily worked, in which there is less trouble from alkali on account of 

 the more perfect drainage and less risk of the accumulation of seepage waters; the 

 other type is a stiff clay or gumbo formed from the disintegration of the shales. 

 These shale soils are extremely fertile when in good condition, but are quite difficult 

 to work. They are easily puddled and are rendered almost impervious to water by 

 the excess of the soluble salts which they usually contain, and it is upon these soils, 

 with their poor underdraiuage, that the greatest amount of trouble has arisen from 

 the accumulation of seepage waters and salts in the overirrigatiou of the soils in 

 the valley. 



"Between these two extremes of samly soil and gumbo, in areas where the layer 

 of sandstone has not been completely removed, the soils are blended in all possible 

 combinations, from the pure type of the sandy soil to that of the gumbo. 



"The following table gives the mechanical analyses of a number of soils from 

 Billings, which indicate the difference in the texture of the soils which has been 

 noticed : 



Mechanical analyses of soils near Billings, Montana. 



Locality. 

 (Miles from 



Billings.) 



Description. 



■r. - 



P. 



7 a 





£ in 



t>.S 



5§ 



2| X i Sandstone bluff soil 



11 W Silty type, creek soil... 



5£ W Sandy gumbo 



5iW .do 



5jW ! do 



3 W '< Gumbo 



5 W Heavy gumbo 



P. ct. 



1 . 22 

 2.98 

 1.56 

 1.91 

 2.35 

 3.20 

 3.74 



P. ct. 

 2.66 



4.4H 

 4.06 

 3.30 

 3.72 

 3.30 

 4.22 



P. ct. 



0.00 



.III) 



.00 

 .00 

 .00 

 .01 



.04 



P. ct. 



0.00 

 .00 

 .00 

 .10 

 .02 

 .40 

 .03 



P.ct. 



0.17 

 .16 

 .20 

 .40 

 .32 



1.58 



.10 



P.ct. P.ct. 



29.39 52.34 



7.96 28.79 



11.72 45.0.1 



15.61 39.59 



21.:. 7 38.27 



20. 40 27. 67 



11.05 24.03 



P. ct. 



9.65 

 17.25 

 19.90 

 21.30 

 22. 55 

 27.30 

 35.55 



20770— Xo. 11- 



-3 



