The area of land where the ocean meets the shore is called a beach. The shape and size of a beach is determined by the forces that continuously deposit and erode sediments from the sea. Beaches vary from rocky coastlines to flat sandy areas. A beach can be a place to swim, sunbathe, or walk. Beaches are also important habitats for birds, marine mammals, and plants.
The sands on many beaches are created by erosion from wave action and deposition by wind. The sands on beaches are usually composed of fine to medium-sized grains. They can range in color from pure white to dark green, depending on the source of the sand. Beaches formed from olivine-rich lavas (such as those on the Isle of Wight or in Kent) tend to be green due to the presence of this iron magnesium silicate mineral. Beaches made from other sources, such as basalt lava flows or carbonate rock formations, tend to be multi-colored and typically have quartz or quartzite compositions.
One of the most common and well-known kinds of beach is a free beach. A free beach is a broad expanse of sand that has been deposited by waves and currents. The sand is often soft, and is usually not crowded with people.
In addition to sand, the beach is composed of other materials such as rocks and tidal debris. The most visible parts of the beach are the sand trough and the dune system. A trough is a depression that forms where the wave breaks on the beach. A dune is a raised system of sand that extends above the water line on the beach. These are often protected by vegetation.
Other noticeable features of a beach are the oscillation ripples, swash or rill furrows and the well-known beach cusps (convex seaward) near the beach margin. Beaches may also be characterized by the existence of linear rip currents, which are powerful channels of tidal flow in the surf.
Beaches are also characterized by swash zones, which are the areas between the trough and the edge of the breaking wave. Finally, a beach may have a submerged barrier reef that is anchored by sediments such as coral, rock or compact clay and which protects lagoons from the open ocean.
A beach is a very complex and dynamic landscape that constantly changes. The shape, width and size of a beach depends on the strength and type of waves that wash onto it, as well as how much erosion takes place along the coast. A beach can also be impacted by human activities, such as littering or fishing. This kind of pollution can prevent wildlife from finding food, or it can prevent sea plants and algae from developing. It can also clog drains and sewage systems. Finally, taking shells from the beach can be harmful to animals that depend on them for shelter or nutrients. All beachgoers should reduce their impact on beaches by respecting the environment and avoiding littering.