MID-ATLANTIC COASTAL PLAIN PHYSIOGRAPHIC AREA: Area Description

The mid-Atlantic Coastal Plain currently covers approximately 56,220 sq km. The areal extent of the region has changed dramatically on a geological time scale with shifts in global climate and sea level. The boundaries of the region are formed by the Atlantic Ocean to the east and the fall line to the west (Figure 1). Between these two boundaries the land slopes gently toward the fall line where it generally reaches an elevation of less than 80 m. A number of terraces and scarps have been recognized within the region that have been considered "high-water marks" formed by shifts in sea level during the Pleistocene. The surface of the land has been reworked considerably by fluvial processes over the past 2-3 million years. Rivers originating within the mountains and piedmont slow and release sediment as they move out across an increasingly flat landscape. As a result, topographic relief declines from the fall line to the Atlantic Ocean. Soils of the region are primarily derived from sediments washed from the Appalachian Mountains and from marine sources deposited during periods of high water.

Water is one of the most dominant features within the physiographic region accounting for nearly 20% of the total area. Water and water-associated habitats are essential to the character of the regional avifauna. Over much of the region, subsidence of the basement rock has "drowned" the mouths of major rivers and lead to the formation of shallow bays. Approximately 1,000 permanently flooded rivers and streams come in close contact with virtually the entire upland surface area. Slowly draining soils have lead to the development of extensive wetlands of numerous types. Nearly 1,000,000 ha of wetlands occur within the region with dominant types including forested wetlands (58%) and salt marshes (28%).

Vegetation within the mid-Atlantic Coastal Plain is most closely associated with that of the southeastern Coastal Plain. More than 100 plant species that are centered in the southeast reach their northern range limit in coastal New Jersey. Many more species reach their limit further south within the region. Upland forests remain an important component of the regional landscape. Forests form a natural gradient in composition from pine-dominated forests on the outer Coastal Plain to hardwood-dominated forests on the inner Coastal Plain.

The mid-Atlantic Coastal Plain was the site of the first successful European settlement in North America. The natural landscape has been altered by European culture for nearly four centuries. By 1790, the region supported more than 600,000 people. In the intervening 200 years, the human population has grown to more than 10.5 million. Currently, the urban crescent from Baltimore south to Richmond and east to Norfolk is one of the fastest growing regions in North America. Growth is expected to continue into the foreseeable future, placing increasing demands on the regions natural resources.