Paleontology and geology
During the first part of the Carboniferous, shallow marine environments, such as tidal flats and channels, were common. By the Late Carboniferous, the Appalachian Mountains were undergoing a third episode of mountain building (the Allegheny Orogeny), as Gondwana slammed into North America. Erosion increased and clastic sediments (mostly sand) were deposited, creating extensive deltas that replaced the previous marine environments. Coal-forming swamps developed in the extreme northwestern part of Georgia. Marine fossils include bryozoans and blastoids, while ferns and lycopod trees are typical fossils found in the coal deposits.