Geology

Georgia is lucky enough to have some of the most varied geology in the United States. We have a total of 5 geological provinces within this state ranging from the barrier islands in the east coast to the Appalachian and Blue Ridge Mountains. The 5 provinces in the Georgia, from oldest to youngest, are the Piedmont, the Blue Ridge, the Valley and Ridge, the Appalachian Plateau and the coastal plain.

The oldest geological area that we have here in Georgia is the Piedmont. The Piedmont consists of metamorphic and igneous rocks. Rocks such as granite, soapstone and kyanite have all been, and some continue to be, mined by the humans. Because of the large quantities of granite found in this area there is an increased risk of radon exposure. Landscape wise the Piedmont consists mainly of rolling hills with a couple of faults. Atlanta and Athens both sit right on the Piedmont.

The next oldest rock formation in Georgia is the Blue Ridge. The Blue Ridge province forms the southern Appalachian Mountains and is made up of metamorphic rocks. The minerals mined from the Blue Ridge include marble, talc and gold. Georgia is on the Southwest end of this geological province, but its boundary is not clear. Some people place the boundary at the Georgia-Tennessee border, others place it a few ridges Southwest of North Carolina, but the most accepted boundary is at the Brevard fault.

To the West of the Blue Ridge is the Valley and Ridge formation. This area of the state consists of sedimentary rocks that have been folded and faulted resulting in the valleys and ridges found there today. The faults along this area are thrust faults which push sheets of sandstone, limestone and shale up on top of each other. Construction grade limestone, barite and ochre are among some of the items mined in this part of the state. The Valley and Ridge formation can be found at the North-western point of the state. Both Cartersville and Chatsworth are located on this geologic formation.
The Appalachian Plateau consists mainly of sedimentary layers that are still horizontal. It is made up of limestone and dolostones at lower elevations, but at higher elevations you can find sandstones, shale and coal beds. This part of the geologic formation is fossiliferous. They contain preserved fossils of land-dwelling animals and plants that lived in coastal forests, marshes and river floodplains.

The youngest of all the formations that makes up a fair amount of our state is the Coastal Plain. The Coastal Plain starts just south of the fall line which cuts through the center of the state from Columbus to Macon and then finally Augusta. The sedimentary rocks that make up the Coastal Plain are a result of sediment eroded from the Piedmont over the last 100 million years. Kaolite and limestone can both be mined from the Coastal Plain. However, the limestone from this area is of a lesser quality than that of the North’s. Because of the limestone bedrock sink holes are common in the southern portion of the state. The permeability and solubility of the stones put this area at a greater risk. As a result a major geologic resource for the area is groundwater. The permeability of the soils in the area allows more water to infiltrate the ground in this part of the state more than any other. Not surprisingly this area of the state tends to rely heavily on ground water as a source of drinking water.

With this wide range of geologic formations and varying climates that go along with them, it’s no wonder Georgia has a fast growing population. We have everything from mountain getaways to wonderful weekends on some of the nicest barrier islands. The beautiful landscapes that be found throughout the state are a result of plate tectonics and the changes that occurred in ocean levels in the past 200 to 300 million years ago.

Frazier, W. F. (2006, January 01). Geologic Regions of Georgia. Retrieved from

http://www.georgiaencyclopedia.com/nge/Article.jsp?id=h-1159

Railsback, B. (n.d.). The Geology of Georgia. Retrieved from

http://www.gly.uga.edu/railsback/GAGeology.html

Posts by Topic