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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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