SOILS OF THE EASTERN UNITED STATES AND THEIR USE XVII. 



GEOGRAPHICAL DISTRIBUTION. 



The Porters loam and Porters black loam are two intimately asso- 

 ciated types of soil which occur only at the higher elevations in the 

 eastern ranges of the Appalachian system from Virginia southward 

 through North Carolina into the extreme western portion of South 

 Carolina. Although of limited geographical extent, these soils pos- 

 sess probably the greatest range in altitude of any types occurring 

 east of the Rocky Mountains, since they extend from the low foot- 

 hills along the eastern slope of the Blue Ridge Mountains to the ex- 

 treme summits of the highest Appalachian peaks, covering the slopes 

 and even the top of Mount Mitchell, at an altitude in excess of 6,700 

 feet. The Porters loam has been mapped in four different soil survey 

 areas in the States of North Carolina and South Carolina to the total 

 extent of 436,160 acres, while the Porters black loam has been encoun- 

 tered in seven areas in Virginia and North Carolina, and a total 

 area of 193,550 acres has been included in these surveys. 



CHARACTERISTIC OF SOIL AND SUBSOIL. 



The surface soil of the Porters loam to a depth ranging from 6 

 to 15 inches is a dark-brown, reddish-brown, or sometimes gray loam. 

 The subsoil to a depth of 3 feet or more is a reddish-brown clay loam, 

 immediately beneath the soil, but grades down into a heavier red 

 clay at greater depths. Small fragments and masses of the parent 

 rock are numerous in the subsoil, and are frequently found in the 

 surface soil, although they only accumulate sufficiently to interfere 

 with cultivation over small local areas. The Porters loam is readily 

 distinguishable from all other soils of the eastern United States 

 through the fact that it is the characteristic soil type of the moun- 

 tain slopes of the western portions of both North Carolina and 

 South Carolina. It lies at the higher altitudes over the foothills 

 and flanks of the mountains and occupies even the crests of the foot- 

 hills and lower ridges. It is distinguished from the mountain soils 



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