42 SOILS: PROPERTIES AND MANAGEMENT 



these soils exist along almost every stream east of the 

 Great Plains Region. Their best and widest develop- 

 ment is found, as the map indicates (See Fig. 4) along 

 the lower Mississippi river, where they may often show 

 a lateral extension of one hundred miles. Extensions of 

 this band are noted along the Missouri, Ohio, and Upper 

 Mississippi rivers. All streams flowing east exhibit 

 areas of such soils, these areas varying with the size and 

 velocity of the stream. 



The soils of the alluvial province may be divided under 

 two heads because of topographic differences (1) the 

 first bottoms, or present flood plains ; and (2) the terraces, 

 or old flood plains. These soils differ in their elevation, 

 drainage, and age, but their general characteristics are 

 similar ; the surface features in both cases vary from a flat 

 to a gently rolling topography (Fig. 6) . Erosion, especially 

 in the terraces, may have obliterated some of the out- 



FIG. 6. Cross-section of typical alluvial soils. (a), bed rock; 

 (r), stream ; (6), present flood plain, a recent alluvial soil ; (c), flood 

 plain terrace ; (d), very old stream terrace, an old alluvial soil. 



standing features. Alluvial soils, being very rich, are 

 particularly adapted to trucking crops, although in most 

 cases they are utilized for more extensive farming. When 

 well drained and protected from overflow, they are the 

 richest and most valuable of soils. 



