SURVEYS BY THE UNITED STATES BUREAU 



117 



typical of the area covered by the soil, this soil likewise is thrown out of the 

 series, because we have reason to know, by observation of the growing crops, 

 that this color difference stands for a difference in the chemical changes which 

 go on in the soil and which are necessary for the welfare of certain crops. 



" In the classification of soils, therefore, the texture is used to determine the 

 place in the series; the structure and color to determine what series the soil 

 can be correlated with. " 



The following table gives the name and area of the soil provinces and the 

 proportion of each that has been covered by the soil survey. It is not unlikely 

 that as the work progresses and as our knowledge of the soils increases it will 

 seem advisable to divide some of these provinces into two or more parts. 



SOIL PROVINCES OF THE UNITED STATES 



ATLANTIC AND GULF COASTAL PLAINS 



The Atlantic and Coastal plains together constitute one of the most impor- 

 tant physiographic divisions of the United States. The Atlantic Coastal Plain 

 extends from the New England states southward to the Florida Peninsula, 

 where the Gulf Coastal Plain begins, and extends thence westward to the 

 Mexican boundary line. It is, however, discontinuous, being interrupted by 

 the alluvial bottoms of the Mississippi River. From the coast the Atlantic 

 Plain extends inland to the margin-of the Piedmont Plateau; that is, to a 

 line passing through Trenton, Baltimore, Washington, Richmond, Raleigh, 

 Columbia, Augusta, and Macon. In its northern extension it is represented 

 by a narrow belt, but widens in New Jersey, and attains its maximum breadth 



