A beach is a strip of sediment that forms along the edge of a body of water, usually made up of sand, pebbles, cobbles, rocks or seashell fragments. Beach material accumulates during periods of accretion and moves away from beaches during periods of erosion. A beach is also called a strand, shoreline, or littoral zone. Beaches are formed by a variety of natural and human forces. The shape and configuration of beaches are constantly changing — each tidal cycle reveals a new set of features.
The beach is often a popular place for recreation and relaxation. The beach can also be a habitat for marine plants and animals. Some beach wildlife includes sea anemones, crabs, fish and birds. In many countries, people visit the beach to swim, sunbathe, and play sports. Some people also collect shells or hunt for sea glass. In addition to recreational activities, a beach can serve as a barrier against erosion, preserving other habitats on the coast.
Beaches are formed by erosion of rock and sediment by the action of waves, wind, and tides. Erosion is a slow, continuous process that may take years to produce noticeable changes at the beach. Beach erosion is most active in the surf zone, where the turbulence of breaking waves excavates troughs in the beach’s sand bottom.
Over time, sand from these troughs is transported by the surf to other parts of the beach and sometimes deposited offshore as a sandbar. The sandbar’s size depends on the amount of sand available to be moved, the strength of waves and currents, and its location along the coast. Some sandbars are crescent-shaped elements with a concave surface at the beach margin; these are called beach cusps.
Other types of sandbars are crescent-shaped formations with a protruding face at the beach margin, called a promontory or headland. These sandbars are formed by erosion of rock and sediment at the point where a continental shelf meets the shoreline. Some promontory heads are covered by thick coral reefs, while others are bare and undeveloped.
Some of the processes that change beaches include attrition (which occurs when rocks rub together), abrasion, hydraulic action, and corrosion. Chemical action can also cause changes in beaches. Some chemicals, such as detergents and pesticides, can destroy coral or other marine life when washed ashore.
Beach pollution is a problem in many places. Plastic debris can choke or entangle marine mammals and birds, and it can prevent algae and sea plants from growing. Pollution can also harm people, especially in areas with poor water quality.
The best way to protect beaches is to reduce the amount of trash that is discarded on them. People can help by not leaving any litter, recycling plastics, and avoiding using chemicals near beaches. In addition, visitors should leave wildlife alone and not remove seashells or other live sea life from beaches. They should also not pick up any tangled ropes or twine on the beach, and should not disturb seaweed or other coastal vegetation.