4 SOILS OF THE EASTERN UNITED STATES. 



soils overlying the plastic clay and the marl at greater depths are 

 sometimes thin remnants of these latter formations. 



The Houston clay, together with other members of the Houston 

 series, is easily distinguished from all other soil types of the Coastal 

 Plain region through its derivation from the underlying marls, the 

 existence of a white or gray chalky material at depths ranging from 

 20 inches to 3 or 4 feet, the existence of calcareous nodules and 

 fragments of shell in both soil and subsoil, and the prevalent brown, 

 drab or black color of the surface soil itself. It can not be confused 

 with the other dark-colored soils of the region, since these are prev- 

 alently alluvial, while the Houston clay occurs only upon the upland 

 prairies. 



SURFACE FEATURES AND DRAINAGE. 



The greater portion of the Houston clay possesses a level to gently 

 rolling surface. Large tracts are almost absolutely level or broken 

 by low ridges from 15 to 30 feet above the general level of the country. 



The surface of the Houston clay lies at elevations ranging from 

 about 125 feet to 500 or 600 feet above sea level. In general the 

 type is fairly well drained, so far as surface run-off is concerned. In 

 fact, erosion occurs over extensive areas of its surface. The inter- 

 nal and subsoil drainage of the type, owing to its stiff, waxy nature, 

 is not particularly good, although the tendency toward granulation 

 in the surface soil somewhat assists in this respect. 



LIMITATIONS IN USE. 



The Houston clay is one of the more plastic clay soils of the upland 

 portion of the Gulf Coastal Plain. In common with other soils of 

 similar texture it is not so well suited to the production of special 

 crops as to the growing of the great staples, including corn, cotton, 

 oats, and hay. In fact very few vegetables, fruits, or other special 

 crops may be grown to advantage upon the type because of its stiff, 

 plastic nature, the large amount of moisture which is retained under 

 normal conditions of rainfall and the difficulty of maintaining perfect 

 tillage during the growing season. The same characteristics which 

 prevent its general use for special crops render it particularly favor- 

 able to the production of the staples. 



The Houston clay is a highly calcareous soil. Numerous analyses 

 of the lime content of the subsoil have shown it to contain from 1\ 

 to 35 per cent of calcium carbonate, while the percentage of lime in 

 the gray chalky material at greater depths is even higher than this. 

 In consequence, wherever drainage conditions are at all favorable, 

 this type constitutes one of the best alfalfa soils to be found in the 

 upland portion of the Gulf States. It also produces other leguminous 



