Marshy tracts are areas of land that are wet and marshy, often characterized by SWAMPS, BOGS, swales, and FENS. SWAMPS are low-lying, wet areas that are usually filled with water and vegetation. BOGS are similar to SWAMPS, but they are usually acidic and have a layer of sphagnum moss on the surface. Swales are shallow depressions in the land that are often filled with water. FENS are wetlands that are fed by groundwater and have a high mineral content. All of these areas are considered marshy tracts and are often home to a variety of wildlife.