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Geologic Processes
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Georgia is divided into four geologic provinces – the Valley and Ridge in northwest Georgia, the Blue Ridge Province in north and northeast Georgia, the Piedmont Province in central Georgia, and the Coastal Plain in south Georgia.  The only province that we will not visit during this field study is the Coastal Plain. 

The Valley and Ridge Province is part of the Appalachian Mountain System.  The rocks in this area are mainly marine sandstone, shale, and limestone and terrestrial sandstone and shale with some coal beds.  These rocks were so compacted that there is little porosity and permeability, so what groundwater there is in this area is generally present in fracture systems.  In areas with limestone, the fracture system can be enlarged as the limestone is dissolved.  This can eventually form caverns and sinkholes.  Areas with sandstone and shale are more stable and will not dissolve.  In the valleys, the streams tend to be linear or trellis and parallel the orientation of the valleys and ridges.  This area is quarried for limestone, dolostone, barite, ochre, iron ore, and coal.  No oil has been found in this region in Georgia, but it has been found in Alabama.

The Blue Ridge Province is also part of the Appalachian Mountain System and extends northwest from Georgia through North Carolina, Virginia, and Maryland.  The rocks of this area are mostly phyllites, mica schists, quartzites, and some marble.  Groundwater is typically present in fracture systems and where there is marble there can be solution enlargement of the fracture system.  In this area, the topography is irregular without definable ridges and valleys, but the highest mountains in Georgia are here.  The stream pattern is mostly dendritic.  Gold, talc, and marble are quarried from this province. 

The Piedmont Province includes most of the Atlanta area and runs to the east of the Appalachian Mountains.  In this area the common rocks are mica schists, quartzites, amphibolites, and gneisses as well as igneous granite.  Groundwater is generally present in fracture systems.  The very common red clay of this area is derived from the intense weathering of feldspar-rich crystalline rocks.  Crushed stone, ornamental granite, kyanite, and soapstone are mined in this province.  The Piedmont Province is generally flat with occasional mountains, mostly due to rock being more resistant to erosion than the surrounding area.  Streams generally follow a dendritic pattern.  The Brevard Fault Zone runs through this region through northwest Atlanta, Duluth, Buford, and Gainesville.  The Chattahoochee River follows this fault zone.

There are no major geologic hazards in Georgia since Georgia is located on a rifted, passive margin of a continent where there is a stable transition from the continental crust to the oceanic crust.  Georgia’s main risk of earthquakes is from distant epicenters, though Georgia does have very small earthquakes.