A beach is a landform along the edge of a body of water, usually an ocean. It consists of loose sediments, including sand, pebbles, shells and sometimes cobblestones. Beaches are continuously reworked and shaped by waves, currents, tides and the sea’s rise. This makes them dynamic and interesting places.
Beaches are popular destinations for recreation and relaxation. There are many different types of beaches around the world, from long stretches of sandy shores to smaller coves and rocky cliffs. Beaches are also home to a variety of marine life, from tiny hermit crabs scurrying in the sand to colorful fish swimming in the sea.
Most beaches are found on the coast, where wave action, currents and tides continuously rework and shape the sediments that make up the beach. The type of sediment that a beach is made up of determines its overall appearance and characteristics. For example, beaches containing mainly silica (SiO2) in the form of quartz are white in color, while those containing mostly feldspars and other minerals are gray, gold-yellow, brown or red in color.
The shape of a beach is determined by the nature of the sediments that it is made up of and whether the waves that move through them are constructive or destructive. Constructive waves tend to deposit and compact the fine sediments on a beach, whereas destructive waves allow the sediment to remain in suspension in turbid water for too long and may cause it to be carried a short distance away by longshore currents and receding tides.
A beach’s slope and shape depends on how the waves break on it, with gentler slopes being favored by constructive waves and steeper slopes by destructive ones. A beach may also contain a trough, which is the area that drains into the sea, and one or more long shore bars, which are slightly raised embankments formed where waves first start to break on a beach.
Beaches can be created and destroyed in very quick succession, with the size and shape of a beach changing hour by hour. The amount of sand on a beach may also vary greatly from season to season, with more sand being added when the weather is warm and dry and less sand being added when conditions are cold and rainy.
Human forces can also influence a beach’s formation, with some beaches being directly affected by bad construction practices on dunes and coastlines and others being indirectly impacted by water pollution, plastic waste and coastal erosion from climate change. Some beaches are actively restored through practices such as beach nourishment, where sand and other sediments are imported and deposited on a beach to help it withstand erosion and retain its features. For more information about beach nourishment, please click here.