n8 SCIENCE AND SOIL 



of about 200 miles in North Carolina. The Gulf Plain extends up the Missis- 

 sippi to the mouth of the Ohio, its inner boundary line passing through or near 

 Montgomery, luka, Cairo, Little Rock, Texarkana, Austin, and San Antonio. 



The surface is that of a more or less deserted plain marked by few hills, 

 slightly terraced with bluffs along streams. The inner margin of the Coastal 

 Plain is usually from 200 to 300 feet above tide water, but sometimes rises to 500 

 feet. The drainage here is usually well established, and the surface is rolling 

 to hilly, and consequently carved and eroded. There is a wide belt border- 

 ing the coast where the elevations are mostly under 100 feet. North of the 

 James River, where the Coastal Plain is narrow and deeply indented with 

 tidal estuaries, drainage is usually well established and the surface is rolling, 

 but in the broad southern extension, where the seaward slope is hardly more 

 than i foot to the mile, drainage is apt to be deficient. Here rain water often 

 remains upon the surface for a considerable time, although the conditions 

 are not comparable with those of a true swamp. The soils in this level section, 

 while composed largely of sand, are compact, usually deficient in organic 

 matter, and not very productive. Many of the flat interstream areas possess 

 such poor drainage that true swamps, such as the Dismal and Okefenokee, 

 have .been formed. Near the coast and along the tidal estuaries, extensive 

 marshes, separated from the ocean by sand barriers, are found. 



The Coastal Plain is made up of unconsolidated gravels, sands, and sandy 

 clays, with less frequent beds of silts and heavy clays. The desposits on the 

 Atlantic coast have been derived mainly from the erosion of the Piedmont 

 Plateau and other inland areas, while the deposits on the Gulf coast have been 

 derived mainly from transported glacial material and from western plains. 

 The materials have been transported and deposited beneath the sea and 

 subsequently exposed by the uplift of the ocean floor. In the more northern 

 parts of the Coastal Plain, and even as far south as Virginia, the character 

 of the deposits has been modified by glacial action and the flooded condition 

 of the streams resulting from the melting of the ice. 



The Coastal Plain deposits range in age from Cretaceous to Recent. Al- 

 though extensive areas of the older sediment are exposed at the surface to 

 form soils, still by far the greater part of the materials is Quarternary or Recent 

 in age. 



The soils are for the most part composed of sands and light sandy loams, 

 with occasional deposits of silts and heavy clays. The heavy clays are found 

 principally near the inner margin of the Coastal Plain. The silts, silty clays, 

 and black calcareous soils, upon which the rice and sugar-cane industries of 

 southern Louisiana and Texas are being so extensively developed, have no 

 equivalents in the Atlantic division. 



Bastrop series. Brown soils with reddish brown to red subsoils occurring 

 as nonoverflow terraces. Cotton, corn, sorghum, alfalfa, melons, and potatoes 

 are successfully produced. 



Crockett series. Dark gray prairie soils underlain by mottled red sub- 

 soils. Derived from slightly calcareous material, the soils of this series are 



