A beach is a landform that consists of sediment (rock fragments, gravel, sand, and mud) that has been deposited along the shoreline of a body of water such as an ocean, sea, gulf, bay, lagoon, estuary, river or lake. It is typically found in places where relatively strong wave action wears down rock and other material, reducing it to the size of grains of sand, and there is usually a lack of strong currents to carry the material away.
Beaches often have a gradual slope to the water, but high energy beaches may have distinct rip troughs and breakers with a distinctive rhythm. The sand on such beaches is frequently coarse, but can also be fine or even clay-like. Beach sediments are often biologically derived, from the breakdown of coral skeletons, shells and other marine organisms, and can therefore have a very different look from a geologically formed beach.
The beach is a very important habitat for a variety of animal species, including birds and marine mammals, as well as for plants. Beaches are also a place where many people relax and enjoy the sun and surf. Beaches also serve as an economic resource for many towns and cities, as they provide opportunities for recreation and tourism.
There are many ways that you can help to protect a beach and its environment. The most important thing is to reduce pollution, especially plastics. Littering can prevent sea animals from finding food and can choke or tangle birds, as well as cause environmental damage by blocking the flow of nutrients that are carried to beaches by longshore drift.
Another way to help protect beaches is to be mindful of their conditions when visiting. This includes respecting the rules of the sandbar, which may be a private property, or the regulations of the state or local government, and leaving wildlife alone, as well as not taking anything from the beach, such as shells or live sea creatures. This will help to keep the beaches clean and healthy, so they can continue to provide a great habitat for wildlife and be used by tourists.
The beach is a dynamic, continually changing natural feature, and changes to the shape of a coastline are caused by a variety of factors, both geological and human. The most significant influences are sea level change and erosion, but also weathering and glaciation, which can significantly alter a beach in just a few years. This process can be sped up by freak wave events such as tsunami, tidal waves and storm surges. The longshore drift of beach sediment is also a major influence, as it can transport sand across a coastline in an offshore direction, but it can be deflected by features such as headlands at either end of a pocket beach, offshore islands and streams over the beach. Longshore drift is essential for the continued existence of a beach, as it keeps it supplied with new sediment, but it can be disrupted by human activity such as building on the coast or using the beach for fishing or boating.