137—Carolina and Georgia Sand Hills

This MLRA (shown in orange in the figure above) is in South Carolina (44 percent), Georgia (34 percent), North Carolina (21 percent), and Alabama (1 percent). It makes up about 8,665 square miles (22,450 square kilometers). It includes the towns of Sanford, Pinehurst, and Fort Bragg, North Carolina; Columbia and Aiken, South Carolina; Augusta and Columbus, Georgia; and Phenix City, Alabama. Interstates 185, 75, 20, 26, and 77 cross this area. Interstate 26 transects a major portion of the area from east of Columbia, South Carolina, to west of Augusta, Georgia. Forts Benning, Gordon, Jackson, and Bragg are in this MLRA. The southeastern edge of the Uwharrie National Forest and the Department of Energy’s nuclear materials production plant, Savannah River Site, are in this area. The Ocmulgee National Monument, just south of Macon, Georgia, is in the MLRA.

Physiography

This area is in a transitional zone between the true Piedmont and the Coastal Plain. Most of the area is in the Sea Island Section of the Coastal Plain Province of the Atlantic Plain. Part of the area in Alabama and the western half of the area in Georgia are in the East Gulf Coastal Plain Section of the same province and division. Parts of the inland edge and half of the northern end of the area are in the Piedmont Upland Section of the Piedmont Province of the Appalachian Highlands. This MLRA is a dissected, rolling to hilly upland. Many of the more dissected areas have stabilized dunes, resulting in very irregular slopes. Elevation ranges from 165 to 660 feet (50 to 200 meters), increasing gradually from south to north. Local relief is mainly 10 to 20 feet (3 to 6 meters), but a few hills are 80 to 165 feet (25 to 50 meters) above the adjacent areas.

The extent of the major Hydrologic Unit Areas (identified by four-digit numbers) that make up this MLRA is as follows: Edisto-Santee (0305), 24 percent; Pee Dee (0304), 23 percent; Apalachicola (0313), 16 percent; Ogeechee-Savannah (0306), 15 percent; Altamaha-St. Marys (0307), 11 percent; and Cape Fear (0303), 11 percent. From North Carolina to Alabama, the major rivers crossing this area are the Lumber, Pee Dee, Little Lynches, Wateree, Congaree, North and South Forks of the Edisto, Savannah, Brier, Ogeechee, Oconee, Ocmulgee, Flint, and Chattahoochee Rivers.

Geology

The Sand Hills area is just below the “fall line,” which marks the boundary between the older crystalline rocks in the Piedmont and the younger, unconsolidated sediments of the Coastal Plain. Deep Cretaceous sands deposited in this ancient shoreline area were reworked during periods of submergence of the Coastal Plain in Pleistocene time. Several areas have deposits of kaolin and high-silica sands that are mined. Stabilized sand dunes are common in the area. Deposits of siltstone, shale, and marl generally lie beneath the coastal plain side of this area, and the crystalline rocks of the Piedmont lie beneath the sands on the inland side.

Climate

The average annual precipitation in this area is 41 to 53 inches (1,040 to 1,345 millimeters). The maximum precipitation occurs in midsummer, and the minimum occurs in autumn. Rainfall occurs during high-intensity, convective thunderstorms in summer. Snowfall is light if it occurs at all. The average annual temperature is 59 to 65 degrees F (15 to 18 degrees C). The freeze-free period averages 250 days and ranges from 220 to 280 days, increasing in length to the south.

Water

Following are the estimated withdrawals of freshwater by use in this MLRA:

Public supply—surface water, 5.7%; ground water, 6.5%
Livestock—surface water, 0.4%; ground water, 0.3%
Irrigation—surface water, 0.3%; ground water, 0.5%
Other—surface water, 78.2%; ground water, 8.1%

The total withdrawals average 2,070 million gallons per day (7,835 million liters per day). About 15 percent is from ground water sources, and 85 percent is from surface water sources. Precipitation, perennial streams, and aquifers provide an abundance of water. The kind and amount of plant growth are severely limited by low moisture in the rapidly permeable, sandy soils that are dominant in this area. The surface water in the area is suitable for all uses. Most of it is used for industry and for cooling thermoelectric power plants.

Ground water is available in both the crystalline igneous and metamorphic rocks aquifer and the Cretaceous sediments aquifer in this area. Both of these aquifers have soft water that is very low in total dissolved solids, having median concentrations of less than 100 parts per million (milligrams per liter). Water in the Cretaceous aquifer is a sodium bicarbonate type and is typically used for industry and public supply. It also is used for irrigating the many golf courses in this area. In North Carolina, the Cretaceous aquifer is actually called the surficial aquifer. Water from this aquifer in North Carolina has low pH, so it can be corrosive. The Middendorf sands are the primary sources of ground water in the part of this area in Georgia. The water in these sands is similar in quality to the water in the surficial aquifer in North Carolina. The crystalline rocks aquifer has a calcium bicarbonate type of water and supplies mostly domestic water in the area. The water in some wells in the crystalline rocks exceeds the secondary drinking water standard for iron.

Soils

The dominant soil orders in this MLRA are Ultisols and Entisols. The soils dominantly have a thermic soil temperature regime, a udic soil moisture regime, and kaolinitic or siliceous mineralogy. They generally are very deep, well drained to excessively drained, and loamy or sandy. Hapludults (Blaney series) and Kanhapludults (Ailey, Pelion, and Vaucluse series) formed in marine sediments on flats, hills, and ridges. Kandiudults formed in marine sediments (Fuquay series) and mixed marine and alluvial sediments (Troup series) on uplands. Paleudults formed in marine sediments (Candor series) and mixed marine and eolian deposits (Blanton series) on uplands and stream terraces. Quartzipsamments (Lakeland series) formed in mixed marine and eolian deposits on uplands.

Biological Resources

This area supports pine-oak vegetation. Longleaf pine is the dominant species. Turkey oak, blackjack oak, bluejack oak, and sand live oak also occur. Little bluestem, panicums, pineland threeawn, and associated grasses and forbs make up the ground cover.

Some of the major wildlife species in this area are white-tailed deer, red fox, gray fox, beaver, raccoon, opossum, cottontail, gray squirrel, turkey vulture, black vulture, crow, screech owl, barred owl, mallard, wood duck, bobwhite quail, Carolina wren, and mourning dove. The large stands of longleaf pine provide critical nesting areas for the red-cockaded woodpecker, an endangered species.

Land Use

Following are the various kinds of land use in this MLRA:

Cropland—private, 12%
Grassland—private, 4%
Forest—private, 58%; Federal, 10%
Urban development—private, 13%
Water—private, 1%
Other—private, 2%

Most of this area is in farms, most of which are part-time or subsistence farms. About one-tenth of the area is federally owned and used for military posts and training areas. The forested areas support pine and scrub oaks. Pulpwood and some lumber are the principal forest products. The cropland in the area is used mainly for corn or cotton. A substantial acreage in the area is used for urban development.

The major resource concerns are controlling water erosion and enhancing the available water capacity of the soils. Conservation practices on cropland generally include systems of crop residue management, diversions, and grassed waterways. Field borders provide cover for bobwhite quail and cottontail. Conversion to a permanent cover of vegetation has been a continuing recommendation for the soils that are low in natural productivity.

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