The Ecoregions of Georgia
This took a little longer than expected to complete, but most future posts will include media and interactive elements. The only heavy lifting I did here was presenting EPA ecoregion data on a single page. First, I created the map above by simplifying the EPA’s level III ecoregion GIS data for Georgia. Below, I’ve compiled Georgia’s Level III and Level IV ecoregions with brief descriptions. Because each ecoregion’s environmental factors and resources differ, they give rise to distinct habitats and biological communities.
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Blue Ridge
Steep mountain slopes, high ridges, cool clear streams, and some of the highest biodiversity in the eastern United States define Georgia’s Blue Ridge. The region includes rugged crystalline mountains, metasedimentary highlands, and lower, drier basins.
Level IV subregions
- Southern Crystalline Ridges and Mountains (66d)
- Southern Metasedimentary Mountains (66g)
- Broad Basins (66j)
Detailed EPA description
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.
- 66d Southern Crystalline Ridges and Mountains: Highest and wettest mountains in Georgia, underlain largely by gneiss, schist, and quartzite, with Brasstown Bald reaching 4,784 feet.
- 66g Southern Metasedimentary Mountains: Rugged but generally somewhat lower than 66d, with slate, conglomerate, phyllite, metagraywacke, and quartzite, including parts of the Cohutta, Rich, and Fort Mountain areas.
- 66j Broad Basins: Lower, drier, and less rugged foothill basins with more saprolite, more pasture, and localized crop production than the adjacent mountain subregions.
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Ridge and Valley
Northwest Georgia’s Ridge and Valley is a folded landscape of long ridges, broad valleys, springs, caves, and mixed agricultural land. Limestone, shale, sandstone, and related rocks produce a varied terrain and a wide range of habitats.
Level IV subregions
- Southern Limestone/Dolomite Valleys and Low Rolling Hills (67f)
- Southern Shale Valleys (67g)
- Southern Sandstone Ridges (67h)
- Southern Dissected Ridges and Knobs (67i)
Detailed EPA description
Sometimes called the Great Valley in Georgia, this relatively low-lying region sits between the Blue Ridge and the Southwestern Appalachians. Extreme folding and faulting created the roughly parallel ridges and valleys, and forests cover about half of the region today.
- 67f Southern Limestone/Dolomite Valleys and Low Rolling Hills: Undulating valleys and rounded hills with caves, springs, mixed forest, pasture, agriculture, and urban/industrial land.
- 67g Southern Shale Valleys: Rolling valleys and low knobs dominated by shale-derived soils, with pasture, hay, corn, soybeans, tobacco, and garden crops.
- 67h Southern Sandstone Ridges: Steep, forested ridges with narrow crests, stony low-fertility soils, and oak-hickory-pine cover.
- 67i Southern Dissected Ridges and Knobs: More crenulated and broken ridges, with mixed geologic materials and a blend of oak, pine, and more mesic forest species.
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Southwestern Appalachians
Georgia’s northwestern plateaus and escarpments form a distinct upland of forest, ravines, steep slopes, and tablelands. Compared with the adjacent Ridge and Valley, this region has more plateau-like landforms and more abrupt relief.
Level IV subregions
- Plateau Escarpment (68c)
- Southern Table Plateaus (68d)
Detailed EPA description
Stretching from Kentucky to Alabama, the Southwestern Appalachians contain low mountains with a mosaic of forest, woodland, pasture, and some cropland. In Georgia, the two Level IV units highlight the difference between steep escarpments and the flatter plateau surfaces of Sand Mountain and Lookout Mountain.
- 68c Plateau Escarpment: Steep forested slopes, deeply incised streams, great local relief, and ravine forests with mixed oak and more mesic species.
- 68d Southern Table Plateaus: Lower, somewhat warmer, and more agricultural than the Cumberland Plateau farther north, with sandstone caprock and mixed oak or oak-hickory communities.
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Piedmont
The Piedmont is Georgia’s broad transitional upland between the Appalachians and the coastal plain, with rolling hills, dissected plains, mixed forests, farms, and growing suburban development. Its varied rocks and soils support several distinct subregions.
Level IV subregions
- Southern Inner Piedmont (45a)
- Southern Outer Piedmont (45b)
- Carolina Slate Belt (45c)
- Talladega Upland (45d)
- Pine Mountain Ridges (45h)
Detailed EPA description
Considered the nonmountainous portion of the old Appalachian Highlands by physiographers, the Piedmont is a complex mosaic of metamorphic and igneous rocks with moderately dissected irregular plains and hills. Much of the region was once cultivated but has reverted to woodlands or been reshaped by urban and suburban growth.
- 45a Southern Inner Piedmont: Higher and more dissected than 45b, with schist, gneiss, granite, pasture, oak-pine and oak-hickory forest, and rapid suburban expansion in Georgia.
- 45b Southern Outer Piedmont: Lower, less rugged, and slightly drier, with loblolly-shortleaf pine, red clayey subsoils, and the Fall Line marking its southern edge.
- 45c Carolina Slate Belt: A smaller Georgia extension of a wider Carolina region, with finer-grained metavolcanic and metasedimentary rocks and broader valleys.
- 45d Talladega Upland: Higher, cooler, and somewhat wetter, with phyllite, quartzite, slate, and generally forested dissected hills and tablelands.
- 45h Pine Mountain Ridges: A narrow belt of quartzite-capped ridges and steep gorges in southwest Georgia with more rocky stream systems and a distinctly mountainous appearance.
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Southeastern Plains
The Southeastern Plains form Georgia’s largest interior lowland region, a broad mosaic of cropland, pasture, woodland, and low-gradient sandy-bottomed streams. Relief is generally lower than the Piedmont but greater than the Southern Coastal Plain.
Level IV subregions
- Sand Hills (65c)
- Southern Hilly Gulf Coastal Plain (65d)
- Dougherty Plain (65g)
- Tifton Upland (65h)
- Coastal Plain Red Uplands (65k)
- Atlantic Southern Loam Plains (65l)
- Tallahassee Hills/Valdosta Limesink (65o)
- Southeastern Floodplains and Low Terraces (65p)
Detailed EPA description
These irregular plains have broad interstream areas and a mixed land cover of agriculture, forest, and pasture. They are developed mostly on sands, silts, and clays of Cretaceous or Tertiary age and include a diverse set of uplands, plains, karst landscapes, and floodplain systems.
- 65c Sand Hills: A narrow rolling belt of sandy, droughty, low-nutrient soils stretching from Augusta to Columbus.
- 65d Southern Hilly Gulf Coastal Plain: More rolling, elevated, and dissected than some neighboring plains, with mixed forest, woodland, and pine plantations.
- 65g Dougherty Plain: Flat to gently rolling karst terrain with sinkholes, springs, cropland, pasture, and limesink wetlands.
- 65h Tifton Upland: A more rolling agricultural upland with well-drained loamy soils and bluff-lined sections near the Pelham Escarpment.
- 65k Coastal Plain Red Uplands: Reddish Eocene-derived uplands that are more agricultural and less forested than the Sand Hills.
- 65l Atlantic Southern Loam Plains: Flatter, lower, and finer-textured than 65k, with agriculture mixed with forest and xeric sand ridges.
- 65o Tallahassee Hills/Valdosta Limesink: Limestone-influenced hills and sink areas with variable relief, intermittent streams, ponds, and mixed hardwood-pine vegetation.
- 65p Southeastern Floodplains and Low Terraces: Riverine corridors of sluggish rivers, swamps, oxbows, and bottomland hardwood forests along Georgia’s major river systems.
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Southern Coastal Plain
Lower, wetter, and flatter than the Southeastern Plains, the Southern Coastal Plain includes terraces, flatwoods, swamps, marshes, barrier islands, and low coastal landscapes. It is one of the most hydrologically distinctive parts of Georgia.
Level IV subregions
- Okefenokee Plains (75e)
- Sea Island Flatwoods (75f)
- Okefenokee Swamp (75g)
- Bacon Terraces (75h)
- Floodplains and Low Terraces (75i)
- Sea Islands/Coastal Marsh (75j)
Detailed EPA description
The Southern Coastal Plain stretches across southeastern Georgia and beyond, containing flat plains, coastal lagoons, marshes, swampy lowlands, and barrier island systems. Historically it supported a variety of forest communities, but today much of the region is in pine cover, wetlands, pasture, and developed areas.
- 75e Okefenokee Plains: Flat plains and low terraces with numerous swamps, bays, acidic lakes, and poorly drained soils.
- 75f Sea Island Flatwoods: Poorly-drained flat plains shaped by changing Pleistocene sea levels and widely covered by loblolly and slash pine plantations.
- 75g Okefenokee Swamp: A peat-rich forested swamp and freshwater marsh system with islands, lakes, tea-colored water, and major wildlife habitat.
- 75h Bacon Terraces: Moderately dissected terraces with subtle scarps, agricultural ridges, pine-covered flats, and narrow floodplains.
- 75i Floodplains and Low Terraces: Broad alluvial river corridors with backwaters, swamps, and bottomland hardwood habitat along major rivers.
- 75j Sea Islands/Coastal Marsh: Barrier islands, estuaries, tidal creeks, marshes, and maritime forests in Georgia’s lowest and most dynamic coastal zone.
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