SOILS OF THE EASTERN UNITED STATES. 



ftd^sfudlly of a more productive development of the 



type, :./....*.."..; 



* Ihr rtisufyf Sufefcfi .-there' ark found, scattered throughout both soil and 

 subsoil, many small* fragments of sandstone and of sandy shale, neither 

 large enough nor sufficiently numerous to impede cultivation. These 

 are fragments of the parent rock from which the soil type has been 

 derived. Larger fragments are locally found upon steeper slopes 

 within and bordering the Dekalb silt loam, but where the accumula- 

 tions of stony material are important, either in number or in extent, 

 the resulting soil has usually been separated as the Dekalb stony 

 loam. 



The Dekalb silt loam is chiefly derived from fine-grained sand- 

 stones and from sandy shales, principally of Carboniferous age, 

 though other shales and sandstones of the same general nature and 

 of the same region have given rise to certain areas of the type. In 

 a few instances only have narrow bands of limestone contributed to 

 the materials composing the Dekalb silt loam. 



The Dekalb silt loam and its associated soils of the same series 

 may easily be distinguished from the majority of the other soils of 

 the regions where they occur through the fact that they are prevail- 

 ingly gray or brown at the surface and at greater depths are char- 

 acteristically yellow. They thus differ from practically all of the 

 other soils of the region which are also derived from sandstones and 

 shales, since the latter possess prevailingly red or reddish-brown 

 subsoils. The red color is only found in the deepest portions of the 

 subsoil of the Dekalb silt loam over areas of rather limited extent. 



SURFACE FEATURES AND DRAINAGE. 



Normally the surface of the Dekalb silt loam is gently rolling to 

 nearly level. It is found as the surface of broad plateau areas and 

 of the level tops of ridges and broad mountains. There are certain 

 areas of the type, to be found chiefly where erosion has deeply dis- 

 sected the Appalachian Plateau Region, which consist of knobs and 

 flat-topped hills with their adjoining slopes. These areas are more 

 rolling or even hilly and sloping, but their extent is limited when 

 compared with the total area of the type. There are also some 

 regions where the type is developed upon sandstone ledges or benches, 

 somewhat below the elevation of the upland but well above the bot- 

 toms of the adjoining valleys. Only in a few areas does the Dekalb 

 silt loam occupy valley positions and these are not typical of this 

 soil either in coloration, drainage, or principal crop adaptations. 

 The materials from which such areas are derived are, however, char- 

 acteristic of the type and the difference in topography and drainage 

 is chiefly responsible for these departures from the normal condition. 



