http://fws.gov/refuge/okefenokee/ - Official Okefenokee National Wildlife Refuge webpage
The Refuge was established in 1937 to preserve the rare and beautiful Okefenokee Swamp.
The Okefenokee Swamp is a vast bog inside a huge, saucer-shaped depression that was once part of the ocean floor. The swamp now lies 103 to 128 feet above mean sea level. Native Americans named the area "Okefenokee" meaning "Land of the Trembling Earth". Peat deposits, up to 15 feet thick, cover much of the swamp floor. These deposits are so unstable in spots that trees and surrounding bushes tremble by stomping the surface.
The slow-moving waters of the Okefenokee are tea-colored due to the tannic acid released from decaying vegetation. The principal outlet of the swamp, the Suwannee River, originates in the heart of the Okefenokee and drains southwest into the Gulf of Mexico. The swamp’s southeastern drainage to the Atlantic Ocean is the St. Mary’s River, which forms the boundary between Georgia and Florida.
The swamp contains numerous islands and lakes, along with vast areas of non-forested habitat. Prairies cover about 60,000 acres of the swamp. Once forested, these expanses of marsh were created during periods of severe drought when fires burned out vegetation and the top layers of peat. The prairies harbor a variety of wading birds: herons, egrets, ibises, cranes, and bitterns.
