SOILS OF SOUTHERN" NEW JERSEY AND THEIR USES. 35 



fare and Woodbury Creek in a low ridge reacliing to 20 or 25 feet 

 above tide level. Southward from Thorofare a gentle slope toward 

 the interior upland begins, carrying the extreme elevation of the 

 tract mapped to an altitude of 40 feet. 



SOILS. 



All of the lower part of the area surveyed lies within the terrace 

 formation which borders the Delaware Eiver and Bay. The basal 

 materials in this vicinity consist of two rather heavy beds; one is a 

 black, micaceous clay of massive structure and greasy appearance, 

 which sometimes carries rather large amounts of greensand, while 

 the other, higher bed, is also dark and micaceous but lacks the green- 

 sand. Both layers affect the underdrainage of the soil types in the 

 area. Upon the lower terrace, slight hollows and depressions remain 

 more moist than the general condition because of the near presence 

 of the clay. Upon the slopes the upper clay bed sometimes comes 

 near enough to the surface to affect subsoil drainage and to con- 

 stitute a rather sticky subsoil material underlying the surface soils 

 at varying depths. 



The actual soil materials of the greater part of the area are to be 

 ascribed to later stages of the deposition of river or estuarine sedi- 

 ments. These sediments give rise to the sandy and sandy loam soils 

 of the upland. These constitute a thin covering over all but the 

 steepest slopes. The soils of the area thus owe their origin primarily 

 to the deposition of tlie older, marine beds and to the later covering 

 of these materials by a thin veneer of later river or bay deposits. 



Four soil types occupy the arable upland portion of the Thorofare 

 area. These are the Sassafras sand. Sassafras sanely loam, Ports- 

 mouth sandy loam, and Collington fine sandy loam. The last covers 

 but a small area. In addition a considerable area of Tidal marsh, 

 some swamp3^ stream bottoms, and the rough, broken land occurring 

 along the slopes from the upland to the streams were necessarily 

 included. 



Sassafras sand. — The surface soil of the Sassafras sand consists 

 of a merely, medium sand of a brown to yellowish-brown color and is 

 6 to 10 inches deep. The surface soil grades into a pale yellowish 

 brown sand, usually rather loose in structure. At a depth ranging 

 from 18 to 24 inches below the surface, the subsoil usually consists 

 of a reddish-yellow to orange fine sand. There is little difference in 

 texture between the surface soil and subsoil. On account of the in- 

 corporation of large amounts of organic manures in the surface soil 

 throughout this region the surface soil frequently seems somewhat 

 more coherent and loamy than the subsoil and its color is somewhat 

 darker than the normal for the type. 



