Strip of land bordering the sea, normally consisting of boulders and pebbles on exposed coasts, or sand on sheltered coasts. Beaches lie between the high- and low-water marks (high and low tides). A berm, a ridge of sand and pebbles, may be found at the farthest point that the water reaches, generally at high tide.
The material of the beach consists of a rocky debris eroded from exposed rocks and headlands by the processes of coastal erosion, or material carried in by rivers. The material is transported to the beach, and along the beach, by longshore drift.
When the energy of the waves decreases, more sand is deposited than is transported, building depositional features such as spits, bars, and tombolos.
Concern for the condition of bathing beaches led in the 1980s to a directive from the European Union on water quality. In the UK, beaches free of industrial pollution, litter, and sewage, and with water of the highest quality, have the right (since 1988) to fly a blue flag.
In 1991 the English Tourist Board and Tidy Britain Group decided jointly to award a Golden Starfish prize to smaller beaches that were clean and had safe access, but whose local authorities had not the funds to finance the public telephones, beach guards, and daily cleaning stipulated for the blue flag award.
Artificial barriers In some places attempts are made to artificially halt longshore drift and increase deposition on a beach by placing barriers (groynes) at right angles to the beach. These barriers cause sand to build up on their upstream side but remove the beach on the downstream side, causing beach erosion. The finer sand can also be moved about by the wind, forming sand dunes.
The beach cycle Beach erosion also occurs due to the natural seasonal beach cycle. Spring high tides and the high waves of winter storms tend to carry sand away from the beach and deposit it offshore (as an offshore bar). In the summer, calmer waves and neap (low) tides cause increased deposition of sand on the beach.
Commercial threats to beaches Apart from the natural process of longshore drift, a beach may be threatened by the commercial use of sand and pebbles by the mineral industry, and by pollution (for example, by oil spilled or dumped at sea).
Beach replenishment Although it is expensive, the high value of tourism, industry, and residential property can make beach replenishment a feasible solution. Miami Beach, Florida, is an excellent example. Between 1976 and 1982 an 18 km/11 mi long, 200 m/656 ft wide beach was constructed using 18 million cubic metres/24 million cubic yards of material dredged from a zone offshore. It replicated a natural beach as far as possible.
Formation of beaches
Coastal features resulting from erosion and deposition
Effects of changing seal level on coastline
Seven Mile Beach, Negril
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