A beach is an area of land where a body of water meets the sea. It is usually made up of sandy or rocky material, and may contain a wide variety of marine plants and animals. It is a popular recreational destination, and many beaches have facilities for bathing, swimming, sunbathing and other outdoor activities.
The term beach is also used for the stretches of sand and gravel that lie next to bodies of water, such as lakes or oceans. These areas are formed when waves wash sediments such as pebbles, shingle, cobblestones and sand onto the shore. The sand that is carried ashore by the waves is often deposited in a pattern that gives the beach its distinctive appearance.
For example, a beach with a large slope is often known as a ‘horn’ beach, because it has a steep ridge of sand that extends out to sea. A beach that has a smaller slope is often referred to as a ‘cusp’ beach because it forms an arc of sand that curves out to sea. Horns and cusps are ephemeral features that appear and disappear with changing wave conditions. Beach erosion and accretion occur rapidly, resulting in dramatic changes in the shape of a beach in just hours.
The most important characteristic of a beach is the amount and type of sediment that it contains. Most beaches are dominated by fine to medium-grained sand, which is primarily carried ashore by wave action. Occasionally, the beach may be dominated by coarser-grained sands originating from the continental shelf or other distant sources. Beaches also contain a small proportion of shell fragments and other types of material that are dragged up by the surf.
Beach erosion and accretion occur in cycles. Well-stabilized parts of the beach tend to accrete, while un-stabilized areas erode. The balance of accretion and erosion will determine the overall form of the beach. Freak wave events such as tsunamis and tidal waves can change the shape of the beach significantly in very short periods of time.
Another factor that influences the formation of beaches is longshore transport, a process that moves sand from updrift beaches or sand bars across the ocean floor towards the beach. This sand is swept back and forth by the waves, sometimes being temporarily trapped behind a pier or other man-made structure on the beach.
Other natural factors that influence beaches include tidal forces and cyclonic storms. These phenomena can substantially alter the shape and profile of a beach in very short periods of time, often re-configuring the entire face of the beach. In addition to this natural variation, most beaches are impacted by the human activity that takes place on them. Depending on the location of the beach, these activities can range from simple recreational uses to the establishment of hotels, resorts and other hospitality venues. The human activities that take place on a beach will also influence the wildlife of that beach.