20 



PHYSICAL CONSTITUTION OF SOIL 



its constituents having almost the same hydraulic value. 

 This deposition in one place of particles of a similar size is 

 characteristic of the soils formed by rivers. 



The sandy soil is from the uplands of Mississippi. It is of 

 considerable fertility, but possesses so little cohesion that it 

 loses its finer constituents in a high wind when left unpro- 

 tected. Unlike the soils previously noticed, it is mainly 

 composed of coarse sand. 



A further very instructive example of the results obtained 

 by a detailed mechanical analysis of soil is furnished by the 

 analyses of certain typical subsoil's in Maryland, published by 

 Whitney (U.S. Weather Bureau, Bulletin 4 ; Wiley, op. cit., 

 249). The separation in this case is into fewer groups than 

 those in Hilgard's analyses. 



TABLE II 



PHYSICAL ANALYSES OF MARYLAND SUBSOILS (WHITNEY) 



The early market-garden soil 1 is a light yellow sand, 



1 In American writings, market-garden soils are spoken of as ' truck land.' 



