Historical Features are physical or cultural features that are no longer visible on the landscape. Examples: a dried up lake, a destroyed building, a hill leveled by mining. The term makes no reference to the age, use, or any other aspect of the feature. A ghost town, for example, is not a historical feature if it is still visible.
Swamp - Poorly drained wetland, fresh or saltwater, wooded or grassy, possibly covered with open water
(bog, cienega, everglades, fen, marais, marsh, pocosin, slough).