| • Science | • People | • Locations | • Timeline |
| Contents | ||
Some geologists consider a beach to be just this shoreline feature of deposited material, but William Bascom (1980) has argued that a beach is the entire system of sand set in motion by waves to a depth of ten meters (30+ feet) or more off ocean coasts. Submerged, longshore bars are therefore also part of the beach. In the Bascom approach, beaches can be viewed as either
The former are described in detail below; the larger geological units are discussed elsewhere in Wikipedia under bars. Both types can be viewed as "beaches."
There are several conspicuous parts to a beach, all of which relate to the processes that form and shape it. That part mostly above water (depending upon tide), and more or less actively influenced by the waves at some point in the tide, is termed the beach berm. The berm is the deposit of material comprising the active shoreline. The berm has a crest (top) and a face — the latter being the slope leading down towards the water from the crest. At the very bottom of the face, there may be a trough, and further seaward one or more longshore bars: slightly raised, underwater embankments formed where the waves first start to break.
The sand deposit may extend well inland from the berm crest, where there may be evidence of one or more older crests (the storm beach) resulting from very large storm waves and beyond the influence of the normal waves. At some point the influence of the waves (even storm waves) on the material comprising the beach stops, and if the particles are small enough (that is, are sand), winds shape the feature. Where wind is the force distributing the grains inland, the deposit behind the beach becomes a dune.
The line between beach and dune is difficult to define in the field. Over any significant period of time, sand is always being exchanged between them. The drift line (the high point of material deposited by waves) is one potential demarcation. This would be the point at which significant wind movement of sand could occur, since the normal waves do not wet the sand beyond this area. However, the drift line is likely to move inland under assault by storm waves.
Beaches are deposition landforms, and are the result of waves or currents moving the sand or other loose material of which the beach is made as these particles are held in suspension or moved by saltation (a bouncing movement of large particles). Beach materials come from erosion of rocks offshore, as well as from headland erosion and slumping producing deposits of scree. A coral reefIn nautical parlance, a reef is a rock, sandbar, or other feature beneath the surface of the water, but shallow enough to be a hazard to ships; see also shoal''. Many reefs result from abiotic processes—deposition of sands, wave erosion planning down rock offshore is a significant source of sand particles.
The shape of a beach depends on whether the waves are constructive or destructive, and whether the material is sand or shingle. Constructive waves move material up the beach while destructive waves move the material down the beach. On sandy beaches, the backwash of the waves removes material forming a gently sloping beach. On shingle beaches the swash is dissipated because the large particle size allows percolation, so the backwash is not very powerful, and the beach remains steep.
Cusps and horns form where incoming waves divide, depositing sand as horns and scouring out sand to form cusps. This forms the uneven edge of a sandy beach.
Some beaches are artificial; they are either permanent or temporary (For examples see MonacoThe Principality of Monaco known as Munegu in the local dialect, is a city state and the second-smallest country in the world, wedged in between the Mediterranean Sea and France along the French Riviera or Cote d'Azur (The Blue Coast). Consisting mostly o, ParisEiffel Tower has become the symbol of Paris throughout the world. Paris is the capital and largest city of France. The city is built on an arc of the River Seine, and is thus divided into two parts: the Right Bank to the north and the smaller Left Bank to, RotterdamRotterdam is the second largest city in the Netherlands (after Amsterdam), located in the province of South Holland. The city is situated on the banks of the Nieuwe Maas River. The name "Rotterdam" is derived from a dam in a small river, the Rotte, which and Hong KongHong Kong has a long coastline which is full of twists and turns with many bays and beaches. Many of them are well sheltered by mountains nearby, as Hong Kong is a place where there is much more mountain area than plain land. As a result, huge waves seldo).
There are several beaches which are claimed to be the "world's longest", including Cox's BazarCox's Bazar in Bangladesh is the world's longest natural beach (120 km). It is located 152 km south of Chittagong. Cox's Bazar ( Sunset in Cox's Bazar ( ., Fraiser Island beach, 90 Mile Beaches in Australia and New Zealand and Long Beach, WashingtonLong Beach is a city located in Pacific County, Washington. As of the 2000 census, the city had a total population of 1,283. History Long Beach was officially incorporated on January 18, 1922. Geography Long Beach is located at 46°21'3" North, 124°3'13" W (which is about 30km). Wasaga Beach, Ontario on Georgian Bay claims to have the world's longest freshwater beach.