Sandhills are found on the fall line in Georgia and along the northern and eastern banks of large Coastal Plain streams in Georgia, Alabama, Florida, and North and South Carolina. They are distinct both as a landform and in the types of vegetation they support. Visually, the sandhills are often striking soils across the southeastern Coastal Plain are typically sandy, sandhills are characterized by thicker sandy deposits one to twenty-five meters deep. An open, dwarf forest or savannah of longleaf pine (Pinus palustris), turkey oak (Quercus laevis), and wiregrass (Aristida beyrichiana) is the most common vegetation on these dunes. Several species of evergreen oak and woody evergreen shrubs as well as many drought-adapted grasses and herbaceous species complete the sandhill flora. Sandhills also form the prime habitat of Georgia's state reptile, the gopher tortoise (Gopherus polyphemus), and of the endangered eastern indigo snake (Drymarchon corais).
Fall-line sandhills differ in origin from the riverine sandhills of the Coastal Plain. Sandhills of the fall line date from the Miocene Epoch (about 25 million years B.C.), when they formed the ancient coastline of the Atlantic Ocean. Riverine sandhills, smaller in extent and less continuous in occurrence, formed when sand from exposed river bottoms was deposited on the northeast banks of Coastal Plain rivers and streams during the Holocene (8,000 years ago to present) and Pleistocene (1.8 million to 8,000 years ago) eras. Dune soils are 95 percent quartz sand and are nutrient-poor, highly permeable, and extremely low in water-holding capacity.