Georgia Ecoregion Descriptions
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Considered the nonmountainous portion of the old Appalachians Highland
by physiographers, the northeast-southwest trending Piedmont ecoregion
comprises a transitional area between the mostly mountainous ecoregions
of the Appalachians to the northwest and the relatively flat coastal
plain to the southeast. It is a complex mosaic of Precambrian and
Paleozoic metamorphic and igneous rocks with moderately dissected
irregular plains and some hills. The soils tend to be finer-textured
than in coastal plain regions. Once largely cultivated, much of
this region has reverted to pine and hardwood woodlands, and, more
recently, spreading urban- and suburbanization.
45a. The Southern Inner Piedmont is mostly higher
in elevation with more relief than 45b, but is generally lower and
has less relief and contains different rocks and soils than 45d.
The rolling to hilly, well-dissected upland contains mostly schist,
gneiss, and granite bedrock. In the western portion, west of Atlanta
and into Alabama, mica schist and micaceous saprolite are typical.
To the east, biotite gneiss is more common. The region is now mostly
forested, with major forest types of oak-pine and oak-hickory, with
less loblolly-shortleaf pine forest than 45b. Open areas are mostly
in pasture, although there are some small areas of cropland. Hay,
cattle, and poultry are the main agricultural products. In Georgia,
urban/suburban land cover has increased greatly within this ecoregion
over the past twenty years.
45b. The Southern Outer Piedmont ecoregion has
lower elevations, less relief, and less precipitation than 45a.
Loblolly-shortleaf pine is the major forest type, with less oak-hickory
and oak-pine than in 45a. Gneiss, schist and granite are the dominant
rock types, covered with deep saprolite and mostly red, clayey subsoils.
The majority of soils are Kanhapludults. The southern boundary of
the ecoregion occurs at the Fall Line, where unconsolidated coastal
plain sediments are deposited over the Piedmont metamorphic and
45c. The Carolina Slate Belt is found primarily
in the Carolinas, although a small area extends into Georgia. The
mineral-rich metavolcanic and metasedimentary rocks with slatey
cleavage are finer-grained and less metamorphosed than most Piedmont
regions. It tends to be less rugged, less dissected, with wider
valleys than other Piedmont areas, and it generally has more silty
and silty clay soils.
45d. The Talladega Upland of the Georgia Piedmont
contains some dissected hills and tablelands that are mostly forested
and at generally higher elevations than 45a and 45b. The geology
is distinctive, consisting of mostly phyllite, quartzite, slate,
metasiltstone, and metaconglomerate, in contrast to the high-grade
metamorphic and intrusive igneous rocks of 45a and 45b. To the west
in Alabama are more mountainous parts of the region, including Alabama’s
highest peak, 2407-foot Cheaha Mountain. The climate of 45d is slightly
cooler and wetter than the other ecoregions (45a, b, c) of the Georgia
Piedmont. Oak-hickory-pine is the natural vegetation type.
45h. The Pine Mountain Ridges, a small, narrow
region in the southwest portion of the Georgia Piedmont, contains
quartzite-capped, steep-sloped ridges that rise 300-400 feet above
the Piedmont surface to elevations over 1300 feet. Pine Mountain
and Oak Mountain are the primary linear ridges trending southwest
to northeast, and several other smaller ridges and mountains between
these, including Bull Trail Mountain, Indian Grave Mountain, Salter
Mountain, and Huckleberry Pinnacle, add to the region’s more
mountainous appearance. The Flint River has cut some narrow, steep
gorges, 400 feet deep, through the ridges. Streams in this region
are often of higher gradient than surrounding areas of 45b, and
contain more rocky and gravelly substrates.
65. Southeastern Plains
These irregular plains with broad interstream areas have a mosaic
of cropland, pasture, woodland, and forest. Natural vegetation is
mostly oak-hickory-pine and Southern mixed forest. The Cretaceous
or Tertiary-age sands, silts, and clays of the region contrast geologically
with the Paleozoic limestone, shale and sandstone of ecoregions
67 and 68, or with the even older metamorphic and igneous rocks
of the Piedmont (45). Elevations and relief are greater than in
the Southern Coastal Plain (75), but generally less than in much
of the Piedmont. Streams in this area are relatively low-gradient
65c. The Sand Hills of Georgia form a narrow,
rolling to hilly, highly dissected coastal plain belt stretching
across the state from Augusta to Columbus. The region is composed
primarily of Cretaceous and some Eocene-age marine sands and clays
deposited over the crystalline and metamorphic rocks of the Piedmont
(45). Many of the droughty, low-nutrient soils formed in thick beds
of sand, although soils in some areas contain more loamy and clayey
horizons. On the drier sites, turkey oak and longleaf pine are dominant,
while shortleaf-loblolly pine forests and other oak-pine forests
are common throughout the region.
65d. The dissected irregular plains and gently rolling low hills
of the Southern Hilly Gulf Coastal Plain ecoregion
developed over diverse bands of sand, clay, and marl formations.
The heterogeneous region that stretches west across Alabama and
into Mississippi, has a mix of clayey, loamy, and sandy soils. It
has more rolling topography, higher elevations, and more relief
than 65g and 65k, and streams have increased gradient. The natural
vegetation is mostly oak-hickory-pine forest, and to the south begins
a transition into southern mixed forest. Land cover is mostly mixed
forest and woodland, pine plantations, with some small areas of
pasture and cropland.
65g. The Dougherty Plain is mostly flat to gently
rolling and influenced by the near-surface limestone. The karst
topography contains sinkholes, springs, and fewer streams in the
flatter part of the plain. The northwestern boundary is gradational,
as more gentle slopes and lower relief are found towards the center
of the region. On the southeast, the Pelham escarpment marks the
boundary with the Tifton Upland (65h). Landcover is primarily cropland
and pasture, with some small areas of mixed forest. Crops such as
peanuts and pecans are common, and cotton production has increased
dramatically in recent years. Natural forest cover consisted of
pines, including longleaf pine, red oaks, and hickories. Many shallow,
flat-bottomed depressions are scattered throughout the region, caused
by solution of the underlying limestone. The wetter, poorly drained
depressions contain blackgum, sweetgum, water oak, and a few pines
and cypress. Many of the limesink ponds and marshes act as biological
oases in the mostly agricultural landscape.
65h. The Tifton Upland of Georgia has more rolling,
hilly topography compared to 65g and 75e, with a mosaic of agriculture,
pasture, and some mixed pine/hardwood forests. Soils are well-drained,
brownish, and loamy, often with iron-rich or plinthic layers. They
support crops of cotton, peanuts, soybeans, and corn. On the west
side of the region, the Pelham Escarpment has bluffs and deep ravines
with cool microclimates that support several rare plants and animals,
as well as species with more northern affinities.
65k. In contrast to the more forested Sand Hills (65c) that formed
mostly on light-colored Cretaceous sands, the Coastal Plain
Red Uplands formed on reddish Eocene sand and clay formations.
Soils are mostly well-drained with a brown or reddish brown loamy
or sandy surface layer and red subsoils. The majority of the area
is in cropland or pasture, with some woodland on steeper slopes.
The Fort Valley Plateau falls within this ecoregion, a relatively
small agricultural area with less relief, flat-topped interfluves,
and less dissection than other parts of the 65k.
65l. Also called the Vidalia Upland in Georgia, the Atlantic
Southern Loam Plains ecoregion is generally lower, flatter,
and more gently rolling than 65k, and has more cropland and finer-textured
soils than 75f. Similar to 65h, it has an abundance of the agriculturally
important Tifton soils, but the region also contains forested areas
that are more sloping or are low, flat and poorly drained. Parallel
to some of the major stream courses are some excessively-drained,
dunal sand ridges with xeric vegetation such as longleaf pine /
turkey oak forests, and some distinctive evergreen shrubs, such
as rosemary and woody mints.
65o. The Tallahassee Hills/Valdosta Limesink ecoregion
combines two slightly different areas, both influenced by underlying
limestone. The Floridan aquifer is thinly confined in this region,
and streams are often intermittent or in parts flow underground
in the karst landscape. In the west, the Tallahassee Hills portion
has rolling, hilly topography that is more forested than 65h. Clayey
sands weathered to a thick red residual soil are typical. Relief
decreases towards the east, and the Valdosta Limesink area has more
solution basins with ponds, lakes, and swampy depressions, as well
as areas with more cropland. The soils are typically brownish. Mixed
hardwoods and pine are found on the clayhill upland soils, while
longleaf pine/xerophytic oak types occur on the sandy, well-drained
65p. Southeastern Floodplains and Low Terraces
comprise a riverine ecoregion of large sluggish rivers and backwaters
with ponds, swamps, and oxbow lakes. River swamp forests of bald
cypress and water tupelo and oak-dominated bottomland hardwood forests
provide important wildlife corridors and habitat. The Georgia portion
of the region includes the major river systems, such as the Chattahoochee,
Flint, Ocmulgee, Oconee, Ogeechee, and Savannah. All of these alluvial
rivers of 65p either originate in or cross the Piedmont (45).
66. Blue Ridge
The Blue Ridge extends from southern Pennsylvania to northern Georgia,
varying from narrow ridges to hilly plateaus to more massive mountainous
areas with high peaks. The mostly forested slopes, high-gradient,
cool, clear streams, and rugged terrain occur on a mix of igneous,
metamorphic, and sedimentary geology. Annual precipitation of over
80 inches can occur on the well-exposed high peaks. The southern
Blue Ridge is one of the richest centers of biodiversity in the
eastern U.S. It is one of the most floristically diverse ecoregions,
and includes Appalachian oak forests, northern hardwoods, and, at
the highest elevations in Tennessee and North Carolina, Southeastern
spruce-fir forests. Shrub, grass, and heath balds, hemlock, cove
hardwoods, and oak-pine communities are also significant. Black
bear, whitetail deer, wild boar, turkey, grouse, songbirds, many
species of amphibians and reptiles, thousands of species of invertebrates,
and a variety of small mammals are found here.
66d. The Southern Crystalline Ridges and Mountains
contain the highest and wettest mountains in Georgia. These occur
primarily on Precambrian-age igneous and high-grade metamorphic
rocks. The common crystalline rock types include gneiss, schist,
and quartzite, covered by well-drained, acidic, brownish, loamy
soils. Some mafic and ultramafic rocks also occur here, producing
more basic soils. Elevations of this rough, dissected region are
typically 1800-4000 feet, with Brasstown Bald Mountain, the highest
point in Georgia, reaching 4,784 feet. Although there are a few
small areas of pasture and apple orchards, the region is mostly
66g. The Southern Metasedimentary Mountains in
Georgia contain rocks that are generally not as strongly metamorphosed
as the gneisses and schists of 66d. The geologic materials are mostly
late Pre-Cambrian and include slate, conglomerate, phyllite, metagraywacke,
metasiltstone, metasandstone, and quartzite, with some schist and
gneiss. Although the highest peaks are lower than in 66d, and parts
of the region have more open low hills, there are some isolated
masses of rugged mountains, such as the biologically-diverse Cohutta
Mountains, Rich Mountains, and Fort Mountain.
66j. The Broad Basins ecoregion is drier, and
has lower elevations and less relief than the more mountainous Blue
Ridge regions (66g, 66d). It also has less bouldery colluvium than
those two surrounding regions and more saprolite. The soils are
mostly deep, well-drained, loamy to clayey Ultisols. Although this
rolling foothills region is mostly forested, it has more pasture
than adjacent regions, and some narrow areas of row crops and truck
crops on terraces and floodplains. Much of the pasture and corn
crops support local cattle, hog, or poultry operations.
67. Ridge and Valley
Sometimes called the Great Valley in Georgia, this is a relatively
low-lying region between the Blue Ridge (66) to the east and the
Southwestern Appalachians (68) on the west. As a result of extreme
folding and faulting events, the roughly parallel ridges and valleys
come in a variety of widths, heights, and geologic materials, including
limestone, dolomite, shale, siltstone, sandstone, chert, mudstone,
and marble. Springs and caves are relatively numerous. Land cover
is mixed and present-day forests cover about 50% of the region.
Forested ridges, and valleys with pasture and cropland, are typical
in many parts of ecoregion 67. Its diverse habitats contain many
unique species of terrestrial and aquatic flora and fauna.
67f. The Southern Limestone/Dolomite Valleys and Low Rolling
Hills form a heterogeneous region composed predominantly
of limestone and cherty dolomite. Landforms are mostly undulating
valleys and rounded ridges and hills, with many caves and springs.
Soils vary in their productivity, and land cover includes oak-hickory
and oak-pine forests, pasture, intensive agriculture, and urban
and industrial. Along the Coosa River floodplain, biota more typical
of coastal plain regions can be found due to the valley and riverine
connection to ecoregion 65 in Alabama.
67g The Southern Shale Valleys consist of undulating
to rolling valleys and some low, rounded hills and knobs that are
dominated by shale. The soils formed in materials weathered from
shale, shaly limestone, and clayey sediments, and tend to be deep,
acidic, moderately well-drained, and slowly permeable. The steeper
slopes are used for pasture or have reverted to brush and mixed
forest land. Small fields of hay, corn, soybeans, tobacco, and garden
crops are grown on the foot slopes and bottom land.
67h. The Southern Sandstone Ridges region encompasses
the major sandstone ridges, but these ridges also have areas of
shale, siltstone, and conglomerate. The steep, forested ridges tend
to have narrow crests, and the soils are typically stony, sandy,
and of low fertility. The chemistry of streams flowing down the
ridges can vary greatly depending on the geologic material. In Georgia
and Tennessee, most of the sandstone ridges are relatively narrow,
but in Alabama, the region also includes the Coosa and Cahaba ridges
that are broader and of younger Pennsylvanian-age sandstone and
shale. Oak-hickory-pine forests are the dominant land cover.
67i. The Southern Dissected Ridges and Knobs contain
more crenulated, broken, or hummocky ridges, compared to the smoother,
more sharply crested sandstone ridges of 67h. Although shale is
common, there is a mixture and interbedding of geologic materials,
including cherts, siltstone, sandstone, and quartzose limestone.
Oak forests and pine forests are typical for the higher elevations
of the ridges, with oak-hickory and a number of more mesic forest
species on the lower slopes, knobs, and draws.
68. Southwestern Appalachians
Stretching from Kentucky to Alabama, these low mountains contain
a mosaic of forest and woodland with some cropland and pasture.
The eastern boundary of the ecoregion, along the abrupt escarpment
next to the Ridge and Valley (67), is relatively smooth and only
slightly notched by small eastward flowing stream drainages. The
western boundary, next to the Interior Plateau’s Eastern Highland
Rim in Alabama and Tennessee, is more crenulated with a rougher
escarpment that is more deeply incised. The mixed mesophytic forest
is restricted mostly to the deeper ravines and escarpment slopes,
and the summit or tableland forests are dominated by mixed oaks
with shortleaf pine.
68c. The Plateau Escarpment is characterized by
steep, forested slopes and high velocity, high gradient streams.
Local relief is often 1000 feet or more. The geologic strata include
Mississippian-age limestone, sandstone, shale, and siltstone, and
Pennsylvanian-age shale, siltstone, sandstone, and conglomerate.
Streams have cut down into the limestone, but the gorge talus slopes
are composed of colluvium with huge angular, slabby blocks of sandstone.
Vegetation community types in the ravines and gorges include mixed
oak and chestnut oak on the upper slopes, more mesic forests on
the middle and lower slopes (beech-yellow poplar, sugar maple-basswood-ash-buckeye),
with some rare hemlock along rocky streamsides and river birch along
68d. The Southern Table Plateaus include Sand
Mountain and Lookout Mountain in northwest Georgia. While it has
some similarities to the Cumberland Plateau (68a) in Tennessee with
its Pennsylvanian-age sandstone caprock, shale layers, and coal-bearing
strata, this ecoregion is lower in elevation, has a slightly warmer
climate, and has more agriculture. Although the Georgia portion
is mostly forested, primarily with mixed oak and oak-hickory communities,
elevations decrease to the southwest in Alabama and there is more
cropland and pasture. The plateau surface is less dissected with
lower relief compared to the the Plateau Escarpment (68c), and it
is slightly cooler with more precipitation than in the nearby lower
elevations of 67f .
75. Southern Coastal Plain
The Southern Coastal Plain extends from South Carolina and Georgia
through much of central Florida, and along the Gulf coast lowlands
of the Florida Panhandle, Alabama, and Mississippi. From a national
perspective, it appears to be mostly flat plains, but it is a heterogeneous
region also containing barrier islands, coastal lagoons, marshes,
and swampy lowlands along the Gulf and Atlantic coasts. In Florida,
an area of discontinuous highlands contains numerous lakes. This
ecoregion is generally lower in elevation with less relief and wetter
soils than ecoregion 65. Once covered by a variety of forest communities
that included trees of longleaf pine, slash pine, pond pine, beech,
sweetgum, southern magnolia, white oak, and laurel oak, land cover
in the region is now mostly slash and loblolly pine with oak-gum-cypress
forest in some low lying areas, citrus groves, pasture for beef
cattle, and urban.
75e. The Okefenokee Plains consist of flat plains
and low terraces developed on Pleistocene-Pliocene sands and gravels.
These plains have slightly higher elevations and less standing water
than 75g, although there are numereous swamps and bays. There are
some highly acidic softwater lakes, mostly with low clarity, darkly
colored water, but the color is variable depending on rainfall.
Soils in the region are somewhat-poorly to poorly drained. The region
has mostly coniferous forest and young pine plantation land cover,
with areas of forested wetland.
75f. The Sea Island Flatwoods are poorly-drained
flat plains with lower elevations and less dissection than 65l.
Pleistocene sea levels rose and fell several times creating different
terraces and shoreline deposits. Spodosols and other wet soils are
common, although small areas of better-drained soils add some ecological
diversity. Trail Ridge is in this region, forming the boundary with
75g. Loblolly and slash pine plantations cover much of the region.
Water oak, willow oak, sweetgum, blackgum and cypress occur in wet
75g. The Okefenokee Swamp is a mixture of forested
swamp and freshwater marsh with some pine uplands. With Trail Ridge
at its eastern boundary, the swamp drains to the south and southwest
and contains the headwaters for the St. Marys and Suwannee Rivers.
The swamp contains numerous islands, lakes, and thick beds of peat.
The slow-moving waters are tea-colored and acidic. Cypress, blackgum,
and bay forests are common, with scattered areas of prairie, which
are comprised of grasses, sedges, and various aquatic plants. The
Okefenokee Swamp is a rainfall-dependent system, and cycles of drought
and fire affect both its vegetation and wildlife distributions.
Most of this region is within the Okefenokee National Wildlife Refuge.
75h. The Bacon Terraces include several relatively
flat, moderately dissected terraces with subtle east-facing scarps.
The terraces, developed on Pliocene-Pleistocene sands and gravels,
are dissected in a dendritic pattern by much of the upper Satilla
River basin. Cropland is mostly on the well-drained soils on the
long, narrow, flat to gently sloping ridges paralleling many of
the stream courses. The broad flats of the interfluves are often
poorly drained and covered in pine, while bottomland forests are
found in the wet, narrow floodplains.
75i. Floodplains and Low Terraces are a continuation
of the riverine 65p ecoregion across the Southern Coastal Plain.
The broad floodplains and terraces of major rivers, such as the
Savannah, Ogeechee, and Altamaha, comprise the region. Composed
of stream alluvium and terrace deposits of sand, silt, clay, and
gravel, along with some organic muck and swamp deposits, the region
includes large sluggish rivers and backwaters with ponds, swamps,
and oxbow lakes. River swamp forests of bald cypress and water tupelo
and oak-dominated bottomland hardwood forests provide important
75j. The Sea Islands/Coastal Marsh region contains
the lowest elevations in Georgia and is a highly dynamic environment
affected by ocean wave, wind, and river action. Mostly sandy soils
occur on the barrier islands, while organic and clayey soils occur
in the freshwater, brackish, and salt marshes. Maritime forests
of live oak, red cedar, slash pine, and cabbage palmetto grow on
parts of the sea islands, and various species of cordgrass, saltgrass,
and rushes are dominant in the marshes. The coastal marshes, tidal
creeks, and estuaries are important nursery areas for fish, crabs,
shrimp, and other marine species. Parts of the region have a long
history of human alterations. Native Americans cultivated corn,
melons, squash, and beans; a Spanish mission period during the 1500-1600's
included crops of citrus, figs, peaches, olives, artichokes, and
onions; and a plantation agriculture economy in the late 1700's
through the 1800's produced indigo, rice, sugar cane, and sea island