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Fall Line Hills District


Atlantic Plain Major Division

Coastal Plain Province

Sea Island and East Gulf Coastal Plain Section

Fall Line Hills District

The Fall Line is the northern boundary of this district as well as the boundary between the Atlantic Plain and the Appalachian Highlands Major Divisions. Geologically, it is the contact between the Cretaceous and younger sediments of the Coastal Plain and the older, crystalline rocks of the Piedmont. Several stream characteristics change as they flow south through this area: rapids and shoals are common near the geologic contact, floodplains are considerably wider on the younger sediments, and the frequency of stream meanders increases.

The southern boundary of the Fall Line Hills District approximates the 250 foot elevation and separates this district from the Dougherty Plain. Eastward, the southern boundary follows the northern extremity of the Pelham Escarpment separating the Fall Line Hills from the Tifton Upland. The southern boundary then closely follows the northernmost occurrence of the undifferentiated Neogene geologic unit which underlies the Vidalia Upland.

The Fall Line Hills District is highly dissected with little level land except the marshy floodplains and their better drained, narrow stream terraces. Stream valleys lie 50 to 250 feet below the adjacent ridge tops. Stream dissection seems to be greatest in the East Gulf portion of this district. Relief gradually diminishes to the south and east. Maximum elevations are approximately 760 feet between Columbus and Macon and gradually diminish to a minimum elevation of 150 feet south of Augusta.

Source: William Z. Clark, Jr. and Arnold C. Zisa, Physiographic Map of Georgia (Atlanta: Georgia Department of Natural Resources, 1976).