SOILS OF THE EASTERN UNITED STATES AND THEIR USE XII. 



THE CARRINGTON LOAM. 



GEOGRAPHICAL, DISTRIBUTION. 



The Carrington loam is a widely developed type of soil in the 

 more northern portion of the central prairie States. It has been 

 mapped in 14 different areas in 6 States, covering an aggregate 

 extent of 1,601,088 acres. With the exception of 8 areas located 

 around the southern extremity of Lake Michigan, practically all of 

 the type thus far encountered has been found in regions west of the 

 Mississippi and principally lying between the Mississippi and Mis- 

 souri Rivers north of the northern boundary of Missouri. It is 

 probable that as the number of soil surveys within this general region 

 is increased, other extensive areas will be found throughout the 

 section. 



CHARACTERISTICS OF SOIL AND SUBSOIL. 



The surface soil of the Carrington loam, to a depth of 10 to 14 

 inches, is a very dark brown to black, mellow loam, which in the 

 more western areas not infrequently contains an appreciable quan- 

 tity of medium or fine sand. The subsoil to a depth of nearly 3 feet 

 is ordinarily a brown or yellowish-brown, compact loam which grades 

 downward into a heterogeneous mass of clay, sand, gravel, and 

 bowlders. This latter material constitutes the unweathered glacial 

 till from which the type is directly derived. The thickness of this 

 glacial till is usually considerable, ranging from 5 or 10 feet in the 

 shallowest portions to 80, or even 150, feet over the greater portion of 

 the region where the Carrington loam is developed. 



Owing to the prevalent dark-brown or black color of the surface 

 soil of the Carrington loam, and of other types associated with it in the 

 Carrington series, it is usually easily distinguished from practically 

 all other glacial soils. It is readily distinguished from the black 

 soils of the Marshall series, through the fact that it contains gravel, 

 and in many instances bowlders, in both the surface soil and subsoil, 

 while these are lacking in the case of the Marshall soil types. Like 

 the soils of the Marshall series, the Carrington loam is principally 

 developed in prairie regions, although in southern Michigan and 



3 



98228 11 



