User:Donald Albury/Coastal barriers

Coastal barriers are landforms along coasts consisting of unconsolidated sediments, primarily sand and gravel. They are generally separated from the mainland by open water, tidal creeks, or marshes. They often shield the mainland coast from the full brunt of storms.

Needed for formation:

• Supply of sediment
• Low slope
• Moderate wave energy
• Low to moderate tide range

Types of coastal barriers:

• Barrier islands
• Barrier spits or peninsulas
• Bay barriers

Barriers are land forms consisting of unconsolidated sediments (sand or gravel) abutting or just off-shore of land masses. Coastal barriers are shaped by waves, wind, tide and currents,

Structure

Coastal barriers are usually linear and parallel to the main shoreline, in most cases forming chains. They are shaped by waves, wind, tides, and longshore drift. Barriers typically consist of the following elements:

• Facing the open-water is the beach, the area that is regularly covered and uncovered by waves and tides. Normal wave action usually adds sediment to the beach, while storms often move sediment off of the beach into deeper water, or across the barrier to beyond the landward edge of the barrier.
• On barriers composed primarily of sand, a frontal dune ridge runs most of the length of the barrier just behind the beach. The dune ridge often protects the area behind the barrier from high water levels and waves during storms, but severe storm surges may overwash the dune ridge, carrying sand to behind the barrier.
• There may be one or more secondary dune ridges behind the frontal dune ridge. Swales lie between such dune ridges, often holding fresh or brackish marshes and ponds.
• The backside or landward margin of a barrier may border on a body of water, such as a lagoon, bay, tidal creek, or lake. In other cases the backside borders a tidal mudflat or tidal marsh.

Distribution

Coastal barriers are found on the coasts of every continent, except Antarctica, and on some larger islands. They are also found on inland seas and large lakes. The largest system of coastal barriers is on the Atlantic coast of North America, stretching 3,100 kilometres (1,900 mi) from Labrador to southern Florida.

Location	Type	Length
Atlantic coast of North America	Low-slope trailing	3,100 kilometres (1,900 mi)
Gulf of Mexico	Low-slope trailing/Marginal	1,600 kilometres (990 mi)
Atlantic coast of South America	Low-slope trailing	960 kilometres (600 mi)
North and west coast of Alaska	Low-slope trailing	900 kilometres (560 mi)
South coast of North Sea	Low-slope trailing	560 kilometres (350 mi)
South coast of Baltic Sea	Low-slope trailing	680 kilometres (420 mi)
East coast of India	Low-slope trailing	680 kilometres (420 mi)
Northeast coast of Siberia	Low-slope trailing	300 kilometres (190 mi)
Ivory Coast, Africa	Medium-slope trailing	300 kilometres (190 mi)
West coast of Australia	Medium-slope trailing	650 kilometres (400 mi)
Southeast coast of Australia	Medium-slope trailing	600 kilometres (370 mi)
Central Pacific coast of Mexico	Steep-slope trailing	500 kilometres (310 mi)
Caribbean coast of Honduras and Nicaragua	Marginal	500 kilometres (310 mi)
Northern Black Sea and Sea of Azov	Inland sea	840 kilometres (520 mi)
Southern Pacific coast of Mexico	Collision	150 kilometres (93 mi)
Southern Pacific coast of State of Washington	Collision	120 kilometres (75 mi)
Copper River delta, Alaska	Collision	80 kilometres (50 mi)

Sources

• "Coastal Barriers Resources System". U.S. Fish and Wildlife Service Ecological Services. April 16, 2018. Retrieved February 13, 2021.{{cite web}}: CS1 maint: url-status (link)
• FitzGerald, D. M.; Buynevich, I. V. (2009). "Coastal Barriers". In Isla, Frederico Ignacio; Iribarne, Oscar (eds.). Coastal Zone and Estuaries (PDF). Encyclopedia of Life Support Systems. UNESCO. Retrieved February 13, 2021.{{cite encyclopedia}}: CS1 maint: url-status (link)
• "Coastal Barriers" (PDF). Environmental Desk Reference for Airport Actions. Retrieved February 13, 2021.{{cite web}}: CS1 maint: url-status (link)
• Otvos, Ervin G. (15 February 2012). "Coastal barriers - Nomenclature, processes, and classification issues". Geomorphology. 139–140: 39–52 – via ScienceDirect.
• "World of Change: Coastline Change". NASA Earth Observatory. Retrieved February 13, 2021.{{cite web}}: CS1 maint: url-status (link)
• Costas, Susana; Ferriera, Óscar; Plomaritis, Theocharis A.; Leorri, Eduardo (8 December 2018). "Coastal barrier stratigraphy for Holocene high-resolution sea-level reconstruction". Scientific Reports. 6: 38726 – via Nature Open Access.
• Cornell, Sean; et al. "Back to Coastal Zones: Plate Tectonics and Coastal Classification". Coastal Processes, Hazards and Society.{{cite web}}: CS1 maint: url-status (link) and other modules
• Glaeser, J. Douglas (May 1978). "Global Distribution of Barrier Islands in Terms of Tectonic Setting". The Journal of Geology. 86: Abstract. JSTOR 30061983.
• Hequette, Arnaud; Ruz, Marie-Hélène (Summer 1991). "Spit and Barrier Island Migration in the Southeast Canadian Beaufort Sea". Journal of Coastal Research. 7: 677–698. JSTOR 4297885.
• Aubrey, D. G.; Gaines, A. G, Jr. (1982). "Rapid Formation and Degradation of Barrier Spits in Areas with Low Rates of Littoral Drift" (PDF). Marine Geology. 49: 257–278 – via Woods Hole Sea Grant.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• "Barrier Island along Arctic Shores". NASA Earth Observatory. June 16, 2011. Retrieved February 14, 2021.{{cite web}}: CS1 maint: url-status (link)
• "What Will Climate Change and Sea Level Rise Mean for Barrier Islands?". NASA News and Features. June 15, 2011. Retrieved February 14, 2021.{{cite web}}: CS1 maint: url-status (link)