The Georgia Piedmont is an elevated area that runs in a northeast to southwest direction in the northern part of the state. It is a part of the larger Southern Piedmont area, which extends from Virginia to Alabama. The Piedmont is the remnant of an ancient weathered mountain chain. In Georgia, the region is characterized by rolling hills, stony outcrops and predominantly red clay soils.
Soil History
Originally the Georgia Piedmont was covered with forests and a sandy surface soil that was sandy-beige or brownish in color. This soil type remains in areas that have never been cleared for agricultural use. This soil overlaid a clay loam and clay subsoil. These are called the Cecil soils and they covered two-thirds of the Georgia Piedmont before farming began. A drastic change in soil type resulted from erosion when forests were cleared and cotton and other row crops were planted.
Effects of Erosion
From 1770 through the 1920s, more and more of the Piedmont was converted to agriculture. R. Daniels, in "Land Transformation in Agriculture," which chronicles the amount of erosion taking place in the Georgia Piedmont from 1700 to 1967. The steep slopes of formerly wooded hillsides were exposed and no longer held in place by vegetation, and the sandy topsoils began washing away, revealing the underlying red clay layers. The washed-away soils clogged rivers and streams, silting them up and filling in millponds.
Red Clay Soils
Since the mid-1800s, the red soils revealed by erosion have been the predominant soil type in the Georgia Piedmont. They consist of kaolinite and halloysite, which are 1:1 aluminosilicate clay minerals and iron oxides. The clays came from the weathering of igneous and metamorphic rocks that are rich in feldspar. The red color is due to the iron oxides. P. W. Mayne and D. A. Brown characterized Georgia Piedmont soil in 2003 as being hard to categorize by the Unified Soil Classification System. They regarded the Piedmont residuum as a dual soil type that shows characteristics of both fine-grained and coarse-grained soils.
Other Soil Types
The U.S. Bureau of Soils in its 1913 bulletin listed the Cecil series as the most important soil, followed by the Louisa series of red and gray soils with underlying red clay. Present in lesser quantities are Iredell soils, which are derived from diorite and have yellow-brown to gray-yellow heavy clay subsoils, and Appling series soils derived from schist and gneiss. They are gray to pale yellow with subsoils mottled or streaked red and yellow. The related less frequently occurring Durham soils have yellow, sandy clay subsoils. Still rarer are the Edgemont series, found on high ridges and hills, which are derived from quartz-schist and quartzite. Molena sand soils are gray to reddish brown with red subsoils. Small areas of the Georgia Piedmont contain Worsham coarse sandy loam of light gray surface soil and yellowish or mottled clay subsoils.
Tags: Georgia Piedmont, soil type, clay subsoils, derived from, iron oxides, Soil Types
