Coastal Geology in our National Parks
Overview
Coastal environments include beaches, estuaries, lagoons, marshes, tidal flats, bluffs, and sea cliffs. Shorelines occur wherever a major body of water, such as a lake, bay, ocean, bayou, or inlet, is in contact with land. At least 97 National Park System units contain coastal and freshwater shorelines.
The water-land interface is a dynamic zone often extending inland to encompass erosion, deposition, landslides (mass wasting), and movement of material (mud, silt, sand, cobbles, and boulders), and extending seaward to encompass tidal flats, mangrove swamps, and other low profile land forms. Within this zone, the shoreline is shaped by meteorologic, hydrologic, and oceanic processes working in concert with surface and bedrock geology. Shoreline processes may occur gradually over time, as with the movement of sandbars, spits, and deltas, or catastrophically, such as during landslides and storm-induced sediment transport.
Like any other geomorphic system, a shoreline habitat responds to and is shaped by physical forces. The repeated movement of water and sediment constructs a shoreline that reaches a dynamic equilibrium between the driving forces of the water body (daily or seasonal wave action, offshore currents, or ice movement) and the resistance of the landmass to erosion. Biota become established on this physically shaped platform through the favorable interaction between prevailing physical forces and biological components of the environment.
Human activity can modify these dynamic processes and habitats. Typical examples of human activities that interfere with natural shoreline processes include dredging and filling, beach nourishment, construction of seawalls and jetties, garbage and sewage disposal, fuel and chemical spills, construction of harbor facilities, housing developments, destruction of estuaries, draining of coastal marshes, and mineral extraction.
Each year people come to the coast to lounge on the beach, build sand castles, and play in the waves. Some people look for solitude, trying to escape the crowds, while others seek the best surf, clearest waters, or whitest sands. Many of America’s favorite beaches are located within coastal National Parks.
The National Park Service has 97 coastal park units including National Seashores, Lakeshores, Recreational Areas, Memorials and Monuments. These coastal parks contain more than 7,300 miles of shoreline, and a wide diversity of geological, biological, and cultural resources.
Increasing pressures and environmental threats such as coastal population growth, pollution, habitat encroachment, and human modifications have dramatically impacted these vital coastal areas. To protect and preserve our national coastal parks, we must have effective and efficient coastal zone management policies.
This website introduces the public and National Park managers to several coastal hot topics including coral reefs, sea-level rise, and the impacts of engineering on coastal environments. In addition, the NPS coastal program is discussed and coastal hazards, monitoring, research, law and policy are explored.