some 50 to 100 kilometers inland from the ocean. The coastal plain is normally wet, including many rivers, marsh, and swampland. It is composed primarily of sedimentary rock and unlithified sediments and is primarily used for agriculture. The Atlantic Coastal Plain includes the Carolina Sandhills region as well as the Embayed and Sea Island physiographic provinces. The Atlantic Coastal Plain is sometimes subdivided into northern and southern regions, specifically the Mid-Atlantic and South Atlantic coastal plains. Geology The Atlantic Plain is generally gently dipping undeformed Mesozoic and Cenozoic sediments, with the sedimentary wedge thickening toward the sea, reaching a maximum thickness of about 3 kilometers (10,000 ft) in the vicinity of Cape Hatteras, North Carolina. Ecology Flora Despite being previously overlooked in research, the Atlantic Coastal Plain is now identified as a global biodiversity hotspot, with over 1500 endemic plant species, and ~70% habitat loss. This endemism is particularly high in the longleaf pine savannas and woodlands, along with the other herbaceous and fire dependent ecosystems of the ecoregion. Despite intermittent flooding, certain refugia have remained continuously terrestrial since at least the late Cretaceous (85-80mya), contributing to endemism. Generally speaking, despite the high diversity of soils, the soil is nutrient poor. This is primarily due to an abundance of well-drained soils, creating a primarily xeric character to the floral makeup of the Atlantic Plain. However, waterlogged soils are also notable, with wetlands and hammocks being important ecological features. The Eastern woodlands are the original, predominant ecosystem of the Atlantic coastal plain. The Atlantic coastal plain upland longleaf pine woodland is an endemic plant community found in most of the Atlantic coastal plain, ranging from Virginia to northern Florida. These woodland savannas are reliant on sandy soils and are fire dependent, lest hardwoods start to dominate. Alongside longleaf pine, typically associated flora includes turkey oak and wiregrass. The Florida longleaf pine sandhill extends the longleaf pine forests into central Florida, with South Florida slash pine flatwoods, Florida sand pine scrub and Florida dry prairie stretching into southern Florida. Longleaf pine woodlands also stretch further west, to eastern Texas. These comprise of East Gulf & West Gulf longleaf pine flatwoods, bisected by the Mississippi Alluvial Plain. To the north, the Atlantic Coastal Plain also broaches into the mesic hardwood forests of the Middle Atlantic coastal forests, followed by the northern Atlantic coastal pine barrens. The southernmost Atlantic Plain contains the only Neotropical