Parallel to the Atlantic coast, Trail Ridge is an elongated mound of sand extending through Florida and Georgia. Ocean surf deposited this sand during higher sea levels of the Pleistocene. Trail Ridge sands contain commercially valuable placer sands, heavy minerals such as rutile concentrated by wave and current as the ridge formed. DuPont Corporation planned to mine Trail Ridge adjacent to the Okefenokee Swamp, but abandoned the idea -- for now -- under public protest.
Some authors describe Trail Ridge as a dam that retains waters of the Okefenokee Swamp, but water level within Trail Ridge is actually higher than the swamp. Although Trail Ridge is not nearly as prominent on the ground as on the map, it marks the lowest major scarp above today's coastal lowlands. Its presence directs the Saint Mary's River south and the Satilla River north.