153A—Atlantic Coast Flatwoods

This MLRA (shown in red in the figure above) is in South Carolina (30 percent), North Carolina (29 percent), Georgia (28 percent), Florida (10 percent), and Virginia (3 percent). It makes up about 28,720 square miles (74,420 square kilometers). It includes Suffolk and Franklin, Virginia; Greenville, Kinston, New Bern, Jacksonville, and Wilmington, North Carolina; Florence, Summerville, and Orangeburg, South Carolina; Fort Stewart, Hinesville, and Waycross, Georgia; and Lakeside and Jacksonville, Florida. Interstates 10, 16, 26, and 40 cross this area. The Green Swamp Private Preserve, the Croatan National Forest, Moores Creek National Military Park, and Camp Lejeune Marine Corps Military Reservation are in the part of this area in North Carolina. The Francis Marion National Forest is in the part in South Carolina. The Osceola National Forest and Camp Blanding, Cecil Field, and Jacksonville Naval Air Stations are in the part in Florida. The west edge of the Great Dismal Swamp in southeast Virginia and northeast North Carolina and parts of the Okefenokee Swamp in Georgia and Florida are in this MLRA.

Physiography

This area is in the Coastal Plain Province of the Atlantic Plain. Almost three-fourths of the area is in the Sea Island Section of the province, the northern end is in the Embayed Section, the extreme southern end is in the Floridian Section, and part of the southwest corner is in the East Gulf Coastal Plain Section. This area is a relatively flat coastal plain crossed by many broad, shallow valleys that have widely meandering of stream channels. Some short, steep slopes border the stream valleys. Elevation ranges from 25 to 165 feet (8 to 50 meters). Local relief is mainly less than 35 feet (10 meters).

The extent of the major Hydrologic Unit Areas (identified by four-digit numbers) that make up this MLRA is as follows: Altamaha-St. Marys (0307), 18 percent; Pee Dee (0304), 17 percent; Edisto-Santee (0305), 16 percent; Suwannee (0311), 12 percent; Neuse-Pamlico (0302), 9 percent; Chowan-Roanoke (0301), 9 percent; Cape Fear (0303), 9 percent; Ogeechee-Savannah (0306), 6 percent; St. Johns (0308), 3 percent; and Lower Chesapeake (0208), 1 percent. Some of the major rivers that cross this area on their way to the Atlantic Ocean are, from north to south, the Blackwater, Nottoway, Chowan, Roanoke, Tar, Pamlico, Neuse, Cape Fear, Little Pee Dee, Pee Dee, Lynches, Black, Santee, Cooper, Edisto, Combahee, Coosawhatchie, Savannah, Ogeechee, Altamaha, Big Satilla, Satilla, and Suwanee Rivers.

Geology

Mostly unconsolidated Coastal Plain sediments occur at the surface throughout this area. These sediments are primarily Tertiary to Quaternary in age. They are a mixture of river-laid sediments in old riverbeds and on terraces, flood plains, and deltas. These young sediments are made up of combinations of clay, silt, sand, and gravel. From central North Carolina to Florida, Cretaceous marine, near-shore shale, sandstone, and limestone deposits occur beneath the surface. Swamps were common in this area prior to agricultural development. The present-day river valleys are extensive and are flat near the coast. The water table typically is close to the surface in these river valleys. Soils having restricted drainage are common throughout the area.

Climate

The average annual precipitation in this area is 44 to 57 inches (1,120 to 1,450 millimeters). The maximum precipitation occurs in summer. Rainfall usually occurs as moderate-intensity, tropical storms that can produce large amounts of rain during fall and winter. Snowfall may occur in the northern third of the area. The average annual temperature is 58 to 69 degrees F (15 to 21 degrees C), increasing to the south. The freeze-free period averages 290 days and ranges from 210 to 365 days, increasing in length to the south.

Water

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

Public supply—surface water, 3.7%; ground water, 7.6%
Livestock—surface water, 1.5%; ground water, 0.4%
Irrigation—surface water, 2.4%; ground water, 2.2%
Other—surface water, 68.5%; ground water, 13.6%

The total withdrawals average 2,695 million gallons per day (10,200 million liters per day). About 24 percent is from ground water sources, and 76 percent is from surface water sources. Rainfall, perennial streams, and aquifers provide an abundance of water. Many of the soils require artificial drainage before they can be used for crops, and some of the sandy soils require irrigation during droughty periods. Most of the surface water used in this area is for cooling thermoelectric power plants. The numerous rivers that flow across the area have good-quality water that is suitable for most uses with minimal treatment.

Water for domestic and some municipal and industrial uses is obtained primarily from wells in the unconsolidated sediments of the Coastal Plain aquifer system in the northern end of this area. This water is moderately hard or hard but is suitable for all uses. The median level of total dissolved solids is generally less than 250 parts per million (milligrams per liter). From central North Carolina to Florida, the principal source of ground water is Cretaceous marine sediments. Water from shale and sandstone aquifers is typically soft, and water from limestone aquifers (Castle Haynes in South Carolina and Floridan in South Carolina, Georgia, and Florida) is hard or very hard. The median level of total dissolved solids is higher than that in the water in the northern part of the area but is still well below the national standard for drinking water. Since the water in all of these aquifers is typically near the surface, nitrate contamination is a problem in some areas. Naturally high levels of fluoride and iron occur in some of the ground water throughout the MLRA.

Soils

The dominant soil orders in this MLRA are Spodosols and Ultisols. The soils in the area dominantly have a thermic soil temperature regime, an aquic or udic soil moisture regime, and siliceous or kaolinitic mineralogy. They generally are very deep, well drained to very poorly drained, and loamy or clayey. Paleaquults formed in marine sediments on flats and in depressions on the coastal plain (Coxville, Lynchburg, Pantego, and Pelham series) and on marine terraces (Rains series). Paleudults (Goldsboro series) and Kandiudults (Norfolk series) formed in marine sediments on uplands. Albaquults (Leaf series) formed in mixed alluvium and marine sediments on flats and terraces. Alaquods (Leon and Mascotte series) formed in marine sediments on flats and terraces and in depressions. Haplosaprists (Croatan series) formed in organic deposits over mixed marine and fluvial deposits on the coastal plain.

Biological Resources

This area supports pine-oak forest vegetation. Loblolly pine, sweetgum, red maple, blackgum, and oaks are dominant in the uplands. Water tupelo, swamp blackgum, bald cypress, sweetgum, and red maple are dominant on the bottom land.

Longleaf uniola, cutover muhly, toothachegrass, panicums, little bluestem, and associated grasses and forbs characterize the understory vegetation.

Some of the major wildlife species in this area are white-tailed deer, feral hog, gray fox, red fox, bobcat, raccoon, skunk, opossum, otter, rabbit, armadillo, squirrel, turkey, and bobwhite quail. The species of fish in the area include largemouth bass, channel catfish, bullhead catfish, bluegill, redear sunfish, spotted sunfish, warmouth, black crappie, chain pickerel, gar, bowfin, and sucker.

Land Use

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

Cropland—private, 15%
Grassland—private, 2%
Forest—private, 61%; Federal, 6%
Urban development—private, 8%
Water—private, 4%
Other—private, 4%

Most of this area is in farms, but some is in national forests or is used for game refuges or related purposes. Some of the forests are farm woodlots, but most are large holdings. Pulpwood is the main wood product. Lumber and naval stores are other wood products. The acreage of cropland is somewhat higher in the northern part of the area than in the southern part and is considerably lower in Florida. Vegetable crops, fruits, melons, sweet potatoes, and Irish potatoes are important crops. Large acreages are used for corn, soybeans, wheat, and tobacco. Some peanuts are grown on the sandy soils in Virginia, North Carolina, and Georgia. Poultry farming is an important enterprise in the northern part of the area and in some parts of Florida. Swine operations are of major importance in North Carolina and Virginia.

The major soil resource concerns are wind erosion and a low soil conditioning index resulting from surface compaction and a low content of organic matter in cultivated areas. Many areas of poorly drained and very poorly drained soils on uplands have been restored to wetland conditions. Wetland restoration improves water quality and provides wildlife habitat.

Conservation practices on forestland generally include forest stand improvement, forest trails and landings, prescribed burning, riparian forest buffers, forest site preparation, bedding, establishment of trees and shrubs, and management of upland wildlife habitat. Conservation practices on cropland generally include crop residue management, establishment of field borders, vegetative wind barriers, and nutrient and pest management.

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