A beach is a strip of land along an ocean, lake, river, or other body of water that is exposed at low tide. The term typically refers to a sandy shore, but may also describe areas of coral or rock. A beach is a dynamic landscape, changing every day as waves and currents deposit and remove material from the area.
A beach usually contains material ranging from the fine sand composing the bulk of a beach to the larger pebbles and cobbles that occasionally make their way onto the shoreline. In addition to sand, beach materials often include seaweed and marine organisms (such as crabs and sea anemones) that can be found on both tropical and temperate beaches.
In the 19th century, beach culture became a national and international phenomenon. Commercial sea bathing emerged, and seaside resorts opened to attract vacationers from urban centers. At the same time, a new romantic ideal of the picturesque landscape encouraged an appreciation for the natural beauty and serenity of the coastal environment. Beaches were portrayed in paintings and prints, and novels such as Jane Austen’s unfinished novel Sanditon celebrated their serene beauty.
Coastal erosion is the primary mechanism that changes the shape of a beach. As the sea erodes, sediment is carried back out to sea, forming a series of terraces that are commonly called beach terraces. Each of these terraces is further divided into a foredune and a backdune, the foredune being closer to the water and the backdune farther from it. A beach that is stabilized by flora with network root systems (creepers, grasses and palm trees) can resist erosion, allowing it to accrete rather than erode.
Beaches that are not stabilized by flora, or are heavily disturbed by people, tend to erode over long periods of time. Freak wave events, such as tsunami and tidal waves, can substantially alter the profile of a beach within hours.
A sand bar is an offshore ridge of coarse sediment, usually comprising sand and gravel, that extends from the shoreline of a beach. Its formation is the result of swirling turbulence created by the breakage of waves off a beach. This turbulence excavates a trough in the beach’s sandy bottom. The sand deposited in the trough, together with sand suspended in the backwash and in rip currents, forms the bar.
The sand of most beaches in the world’s temperate regions is composed of quartz, although some contain feldspars and a few have heavy minerals. In the tropics, many beaches have a composition characterized by calcium carbonate in the form of the skeletal remains of seashells and small round or oval particles known as oolites. Other sand types, such as clay, silt, shingle and boulders are also encountered.