THE SOIL AND ITS MANAGEMENT 55 



57. ^olian soils. ^Eolian soils are deposited by wind action. 

 Soil may be drifted by the wind, just as snow is drifted. Most 

 of the prairie soils in the Western states have been more or 

 less affected in their formation by the action of the wind. In 

 a few localities a sedentary soil has been covered to a depth of 

 several feet by fine sand which the wind has carried. There 

 is an important type of aeolian soil known as loess soil, which 

 is believed to have been formed in part by wind and in part by 

 water. An interesting example of loess may be seen along the 

 Mississippi and Missouri rivers and is frequently called " bluff " 

 soil. It is yellowish brown in color, well aerated, very deep and 

 fertile, and therefore particularly favorable for growing all kinds 

 of fruit. The greatest areas of it occur in western Missouri, 

 western Iowa, and eastern Nebraska. A very important area of 

 loess soil is found in China. 



58. Colluvial soils. Colluvial soils are those which have 

 been moved but a short distance. They occur principally at the 

 foot of mountain slopes, where they have been formed by the 

 soil sliding or washing down the mountain side. This soil is 

 so small in area as to be of little agricultural importance in 

 North America, but some of the important vineyards of Europe 

 are of this type. 



59. Significance of soil type. The glaciers rendered a splen- 

 did service to civilization not only in grinding the rocks into 

 powder and leveling the earth's surface, but also in transport- 

 ing the fine soil material from the frozen North and spreading 

 it over the wheat and corn belts. Of the sedentary soils the lime- 

 stone supports the highest type of agriculture. Sandy soils are 

 generous, but do not have the lasting powers of the limestone 

 soils. Granite soils are stingy, and on account of this they wear 

 well. Alluvial soils are the most productive of the transported 

 soils, and indeed of all soils, but they, are more or less subject 

 to flood and frequently require drainage. As a rule the bottom 

 lands are not as satisfactory places in which to live as are the 

 uplands. 



