Slopes are long and have low gradients across broad interfluves. Texture of the marine and fluvial sediment parent material is variable. Soils are acidic and have low base saturation. Histosols are common in closed depressions and in large swampy areas. In northern Florida and southern Georgia, MLRA 153A extends inland from the seacoast as much as 175 km, but the width of the remainder of the belt typically ranges from 50 to 75 km.
Natural vegetation is pine-oak forest.
Loblolly pine and upland oaks occur on uplands, and water tupelo, sweetgum, oaks, and swamp blackgum occur in the lowlands. Much of the original timber has been harvested and pine plantations have been established. Various grasses and forbs adopted to poorly drained soils provide understory. Most of the forest holdings are large, being owned by companies such as Weyerhauser. Pulpwood is the main product, but lumber and naval stores are also harvested.