4 SOILS OF THE EASTERN UNITED STATES. 



chiefly upon the condition of the subsoil drainage. In the better 

 drained areas it is usually grayish brown or gray or drab, while at 

 greater depths and in localities where the drainage is poor the subsoil 

 is of lighter drab or bluish color. 



It is a marked characteristic of the Fargo clay loam, wherever it 

 has been encountered, that the subsoil is highly calcareous. A large 

 number of determinations of calcium carbonate have been made in 

 connection with the study of this soil type, and in the majority of 

 cases the calcium carbonate content of the subsoil of the Fargo clay 

 loam has ranged from 3 to as high as 24 per cent. This is unusually 

 high when compared with the lime content of other soils and subsoils. 



This characteristically calcareous subsoil distinguishes the Fargo 

 clay loam from the black soils of the Clyde series, while the Fargo 

 clay loam is distinguished from the dark-colored soils of the Wash- 

 burn series, in that the latter contain considerable quantities of stone, 

 while the soils of the Benoit series are underlain by a substratum of 

 gravel. The Fargo clay loam is distinguishable from the Carrington 

 black clay loam through the fact that it occupies the beds of extinct 

 glacial lakes of some size, while the Carrington black clay loam con- 

 sists of an accumulation of dark-colored surface material overlying 

 glacial till which frequently constitutes the subsoil of that type. 



SURFACE FEATURES AND DRAINAGE. 



In all areas where it has been encountered the topography of the 

 Fargo clay loam is marked by the almost level character of the land 

 surface. The slopes w 7 ithin the area of this type are usually not 

 greater than 2 or 3 feet to the mile, while the greater proportion of 

 its area possesses a slope not in excess of 1 foot to the mile. In the 

 areas of- its broadest development, such as the Red River Valley of 

 the North, the surface of the Fargo clay loam and of its associated 

 types in the Fargo series is generally so level that one is reminded of 

 the surface of a vast body of w r ater, like the sea. In traveling across 

 such regions the surface of the plain is visible only for a distance of 

 3 or 4 miles. It is bounded by a straight horizon which seems to rise 

 around the position occupied b}^ the observer like the rim of a saucer. 



High buildings, such as grain elevators, and the tops of houses and 

 of grain stacks are first visible, and finally the entire structure comes 

 gradually into full view as it is approached. In spite of this almost 

 absolutely level appearance of the surface of the Fargo clay loam. 

 there are minor low undulations and swells interspersed with shallow 

 depressions and broad level areas which give a slight diversity to the 

 surface features of the type, and Avhich aid materially in the natural 

 drainage of a portion of its extent. 



The major streams, particularly the Red River of the North, have 

 cut channels into the bed of the extinct glacial lake to a depth of 20 



