12 



The type name results from combining the class name of the sur- 

 face material with the series name (Fargo, Carrington, etc.). The 

 class (loam, silt loam, clay, etc.) is determined by the texture of the 

 surface soil, the portion encountered by tillage implements, as decided 

 upon in the field by the experienced surveyor and later confinned in the 

 laboratory by mechanical analysis of typical samples. The series name 

 as it serves as a key to all the important properties of the type except 

 the texture of the surface stratum, is based upon the color and content 

 of organic matter in both surface soil and subsoil, the subsoil profile, 

 the topography, the origin and the mode of formation as well as any 

 prominent chemical dififerences- insofar as they are likely to affect 

 agricultural practice. A series includes all the types that differ from 

 one another only in the texture of the surface stratum. The total 

 nimiber of series in the United States so far recognized by the Bureau 

 of Soils amounts to abouli 600 and the tvpes to a little in excess of 

 1.650. 



The soils of the Carrington series are derived from the weather- 

 ing of the glacial drift. (I^arrington loam occupies the rolling up- 

 lands, is generally well drained and originally was nearly all covered 

 with deciduous forest — the Big Woods. Carrington silt loam is con- 

 fined almost entirely to those higher-lying portions of the county which 

 were originally covered by prairie. On the Wisconsin the drainage is 

 good, while on the Kansan it is much poorer than that of the Carring- 

 ton loam. Boulders, some very large, occur in small numbers on both. 



The Carrington loam is described (11, p. 22-23) as "a brownish 

 black or yellowish brown silty loam, 12 to 24 inches deep, grading 

 into a heavy yellow clay, which usually exceeds a depth of 15 feet. 

 The texture of the surface soil is for the most part uniform, but the 

 color and depth are variable. A depth of 15 inches is more typical than 

 either of the extremes. There are few stone fragments in the material 

 to a depth of three feet, though these increase in quantity with depth." 



The Carrington silt loam (11, p. 26) is "a. grayish-black or black 

 heavy silty loam, with a depth of 15 inches, grading into a drab or 

 brownish silty clay which at about 24 inches is underlain by dark yel- 

 low clay. The soil is generally unifomi in texture and has a high 

 content of organic matter." 



The Fargo silt loam is described (11, p. 32) as "a black clay or 

 silty clay loam from 10 to 15 inches deep, grading into a dull colored 

 clay which at 20 to 30 inches changes to a yellow and gray plastic clay. 

 Beneath this there usually occurs a thin layer of sand, sandy clay or 

 gravel. In the southeast corner of the county the Fargo silt loam occu- 

 pies a part of the original plain of the Kansan drift, but elsewhere it is 

 a bottom-land type. The topography is generally level but is character- 

 ized by very gentle slopes as it approaches sloughs and streams. The 

 areas are generally poorly drained and water is often found within 

 the 3-foot section in the bottoms." 



"The soil material along the sloughs has been washed from the 



