86 SOIL PHYSICS AND MANAGEMENT 



occur, rendering the use of farm machinery somewhat difficult. 

 They give fair yields of corn, potatoes, oats, hay, and fruit. 



Holyoke Series. The soils are brown to dark yellow in color. 

 The subsoils are yellow and somewhat heavier than the soils. They 

 are of glacial origin and derived from metamorphie, diabase and 

 crystalline rocks. The topography is rough and the soils are mod- 

 erately productive. 



I Kewaunee Series. This series is characterized by grayish to 

 reddish brown or pinkish soils overlying pinkish red silty clay and 

 rather calcareous subsoils. They are derived from till and contain 

 more or less angular pebbles. The topography varies from undu- 

 lating to hilly, but the underdrainage is generally poor. 



-' Knox Series. These soils are light brown and are derived from 

 loessial or other wind blown deposits. The topography is gently 

 undulating to rolling. Grain crops constitute the chief agricultural 

 products. About three million acres have been mapped. 



Lackawanna Series. These soils are derived from glacial drift 

 that forms a relatively thin mantle overlying the red shales and 

 limestones. The topography is slightly rolling to hilly and moun- 

 tainous. 



Lexington Series. Lexington soils are gray to yellowish gray 

 in color and mellow in structure. The subsoil is yellow to brown, 

 with a tinge of red in places, and is often somewhat heavier than 

 the soil. Drainage is good and the topography is moderately rolling 

 to hilly. The types are derived from loess with orange sand a few 

 feet below the surface. These soils are adapted to corn, cotton, 

 forage crops, vegetables, and strawberries. 



Marion Series. These soils are gray, white or ash colored. 

 The subsoils are white at the top, the white layer varying in thick- 

 ness from 2 to 12 inches and averaging about five inches. This 

 layer is compact, impervious, whitish silt or very fine sand, often 

 containing iron concretions and locally known as "hard-pan." Be- 

 neath this the true subsoil is a gray, light yellow to reddish yellow or 

 mottled brownish yellow, hard, impervious clay containing occa- 

 sional concretions of iron and lime. The topography is flat to un- 

 dulating. Drainage is poor. They are derived from modified loess. 



Marshall Series. The Marshall series includes the dark col- 

 ored upland loessial soils which predominate in the great prairie 

 region of the central west. The surface soils have a dark brown 

 to. black color. The topography is level to rolling and artificial 

 drainage is usually necessary to "secure best results. They aje very 



