KINDS OF SOIL 63 



show no layers, being of the same nature through- 

 out. The largest deposit of loess soils in the 

 United States is the alluvial loess of the great 

 Mississippi Valley, including thousands of square 

 miles of the "prairie" soil of the central states. 

 They are found in southern Michigan, Ohio, Illinois, 

 Indiana, Iowa, Kansas, Oklahoma, Tennessee, 

 Arkansas, Missouri, Kentucky, Alabama, Mis- 

 sissippi, Louisiana. Smaller areas of alluvial loess 

 soils are found in the valleys of the Connecticut, 

 Ohio, and other rivers; while wind-formed loess 

 soils are found in California, Washington, Oregon 

 and many other western states. There are large 

 deposits in the valley of the Rhine, the famous 

 steppes of Russia and the inland plains of China. 

 Loess soils are noted for their great depth and 

 remarkable fertility. In China they have pro- 

 duced bountiful crops for over three thousand 

 years, with little apparent diminution of fer- 

 tility. The richness of our own loess lands 

 in the central West is well known. There 

 the soil is from 5 to 150 feet deep. Although 

 loess soils may differ very widely chemically, 

 they are all about the same physically a fine 

 silt or clay, possessing great tenacity. Most 

 of the loess soil of the West contains from 

 55 to 75 per cent, of silt and from 6 to 15 per 

 cent, of clay. 



ADOBE SOILS 



These peculiar soils are found only in the arid 

 West, especially in Utah, Arizona, southern 

 California, New Mexico, western Texas, and 

 in the elevated valleys of Colorado and New 

 Mexico. They consist very largely of clay and 

 silt, partly worn down from surrounding high land 



