A beach is a strip of loose sediment, typically sand and pebbles, that accumulates along a body of water, such as the sea. The beach is usually located at the edge of a rocky or cliffy coast, and it may also encompass a lagoon, sandbar, or lagoon island.
Beaches form by erosion, which is the wearing away of rocks and other materials by wind and waves. This process can occur over a very long period of time, and it is why beaches have such a variety of appearances and textures. The types of rocks and materials that make up a beach are determined by its geological history, as well as the climate and water conditions.
Although they are often associated with oceans, beaches can actually be found on shores of other bodies of water as well—from rivers to lakes and even large ponds. They are characterized by their flatness and the presence of loose particles such as sand, pebbles, shells, and sometimes rocks.
Most beaches are dominated by fine-grained sand. This material is derived from the weathering of rocks far inland and carried by streams and rivers until it reaches the coastline. As waves break and erode the rocks, they transport and deposit the sand, which eventually builds up into the beach. In addition to sand, beaches can contain other sedimentary materials such as clay and silt, which are derived from weathering and erosion of larger rocks.
Unlike the rest of the coastline, which is primarily made of rock formations, a beach tends to have a soft texture and be gently sloped, especially at low tide. It is a place where people can walk, enjoy the sun, surf or sail, collect shells and other marine debris, and see a great diversity of plants, animals, and birds. Beaches can be found on all continents except Antarctica and are one of the most common landforms in the world, covering about a third of the global coastline.
A beach can be divided into several different segments when viewed from above, depending on the kinds of sediment involved and the configuration of its boundaries. The area nearest the water is called the foredune, or berm, and it is formed by the accumulation of sand from past wave action. The sand in the foredune may be further consolidated by vegetation, and this helps to protect it from erosion. Beyond the foredune is a series of terraces with troughs and ridges that are shaped by sandbars and the movement of sand between them.