Georgia Ecoregions

 

The classification of Georgia’s geological and ecological regions varies somewhat between sources; the vast majority of writings on this topic, however, list six such regions in the state. FOr the purposes of this article, these are, moving northwest and inland: Lower Coastal Plain, Upper Coastal Plain, Piedmont, Blue Ridge Mountains, Ridge and Valley, and Plateau.


The Lower Coastal Plain extends from the shore to approximately 65 miles inland. Georgia's Atlantic coastline stretches for approximately 100 miles[1] and is dotted with hundreds of barrier islands, or sandbars, six of which are composite barriers with cores of beach or dune deposits[2]. The largest of these sandbars is Cumberland Island, at approximately 18 miles in length and up to 8 miles in width [3]. Deposits left over from shorelines of the Late Pleistocene era can be found throughout[2].  Seasonal spring tides are higher in this region of the Atlantic coast of North America than in any other, ranging as much as ten feet [2].


The Upper Coastal Plain covers the bulk of the southern and southwestern parts of Georgia. It is defined on its eastern edge by the Okefenokee Swamp National Wildlife Refuge, and on the north by the Fall Line, the point delineating the Piedmont plateau and north of which rivers become difficult to navigate [2]. Thin, sandy soils dominate the region, remnants of an ocean channel that once connected the Atlantic Ocean and the Gulf of Mexico[4]. This region has more precipitation, and thus wetter soils, than the Lower Coastal Plain[5].


The Piedmont region is named after the Piedmont plateau, which extends south and east from the foot of the Appalachian mountains and stretches roughly from Alabama to Virginia. In Georgia, the Piedmont ranges in elevation from 500’ to 1,700 above sea level[6]. Its soil, the red clay characteristically associated with Georgia, is very years; though arable, it is not nearly as fertile as the darker, more nutrient-rich soils in the Plains region, due to hot temperatures and heavy rainfall over long periods having leached it of most minerals save for iron, silica and aluminum[7]. Granite is abundant in several areas of the region[8].


The Blue Ridge Mountains region is part of the southern Appalachian mountain range, and is centered around the far northeastern portion of the state, along its borders with the Carolinas and Tennessee[9]. Its peaks can exceed 4.000’ above sea level, and include the highest peak in Georgia at 4,784’, Brasstown Bald[9]. Higher elevations in this region can experience more than 70” of rain annually; some of this terrain is home to a diverse array of wildlife, including several salamander species, unique to the area[10]. Many cave formations have been facilitated over the eons by an abundance of limestone[11].



The Ridge and Valley region is located in northwest Georgia, featuring symmetrical folds of rock underlying ridge formations oriented northeast-to-southwest[12]. These ridges are composed of either sandstone or chert, with shale or limestone forming the valley floor[13]. Elevations typically range from 700’ above sea level at the valley floor to 1,600’ at the highest peaks[6]. Over roughly the last 250 million years, swaths of Cambrian rock strata have been exposed by erosion of convex rock folds[12].


The Plateau region, farthest inland at the far northwest corner of Georgia bordering Alabama and Tennessee, is by far the smallest in Georgia; it is composed of Georgia's portion of the  Cumberland Plateau, totaling 300 square miles[6]. The region features three major mountains: Lookout, Pigeon and Sand[14]. Local deposits of iron ore were once mined here, similar in composition to those found elsewhere in the Cumberland Plateau, but have since been depleted[14]. This region also contains the only known coal deposits in Georgia[6].



Bibliography



1. Jackson, E. and Stakes, M. (2004). Georgia Coast. In GeorgiaInfo. Retrieved May 22, 2016. from http://georgiainfo.galileo.usg.edu/topics/geography/article/georgia-coast

2. Henry, V. J. (2005). Geology of the Georgia Coast. In New Georgia Encyclopedia. Retrieved May 22, 2016 from http://www.georgiaencyclopedia.org/articles/science-medicine/geology-georgia-coast

3. Geography. Retrieved from http://cumberlandisland.com/the-island/geography

4. Kirkman, L. K. (2004). Upper Coastal Plain. In New Georgia Encyclopedia. Retrieved May 22, 2016 from http://www.georgiaencyclopedia.org/articles/geography-environment/upper-coastal-plain

5. Griffin, G. E., Omernik, J. M., Comstock, J. A., Lawrence, S., Martin, G., Goddard, A, Hulcher, V. J., and Foster, V. (2001). Ecoregions of Alabama and Georgia [poster]. Reston, Virginia, U.S. Geological Survey.  Retreived May 22, 2016 from ftp://ftp.epa.gov/wed/ecoregions/al/alga_front.pdf

6. Geographical Regions of Georgia. Retrieved from http://georgiainfo.galileo.usg.edu/topics/geography/article/geographic-regions-of-georgia

7. Georgia Red Clay: Why are Georgia Soils Red? Retrieved from http://www.nrcs.usda.gov/wps/portal/nrcs/detail/ga/soils/?cid=nrcs144p2_021871

8. Ouzts, C. (2004). Granite. In New Georgia Encyclopedia. Retrieved May 22, 2016 from http://www.georgiaencyclopedia.org/articles/science-medicine/granite

9. Seabrook, C. (2006). Blue Ridge Mountains. In New Georgia Encyclopedia. Retrieved May 22, 2016 fromhttp://www.georgiaencyclopedia.org/articles/geography-environment/blue-ridge-mountains

10. Blue Ridge Province. Retrieved from http://www.georgiawildlife.com/node/1057

11. Loucks, C., Olson, D., Dinerstein, E., Weakley, A., Noss, R., Stritholt, J., and Wolfe, K. Appalachian-Blue Ridge forests. Retrieved from http://www.worldwildlife.org/ecoregions/na0403

12. Ridge and Valley Province. Retrieved from http://www.georgiawildlife.com/node/1056

13. Chowns, T. (2006). Valley and Ridge Geologic Province . In New Georgia Encyclopedia. Retrieved May 22, 2016 from http://www.georgiaencyclopedia.org/articles/science-medicine/valley-and-ridge-geologic-province

14. Chowns, T. (2006). Appalachian Plateau Geologic Province. In New Georgia Encyclopedia. Retrieved May 22, 2016 from http://www.georgiaencyclopedia.org/articles/science-medicine/appalacian-plateau-geologic-province

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