A beach is a strip of land alongside a body of water, usually an ocean or a lake. It is composed of loose materials, such as sand, gravel, pebbles and shells, that have been moved by the wind and waves. Beaches can be found all over the world and are popular places for recreational activities such as swimming, sunbathing and playing beach sports.
The size and composition of a beach changes over time, as sand is deposited during periods of accretion and is then removed by waves during periods of erosion. As a result, beaches have an infinite variety of patterns and shapes. They can be wide and sandy, or narrow and rocky. Some have high levels of shell content, while others are almost entirely free of shells. Beaches can also be shallow and muddy or deep and sandy, with or without a reef system.
Waves continually beat rocky cliffs and cause rocks to come loose. These huge boulders are then weathered, sometimes down to the size of a grain of sand. This process is called beaching, and it helps to shape a beach.
In general, a beach is made up of sand, but it can be made up of a mix of other materials, including pebbles, cobbles and rock. The type of material in a beach depends on the source and energy of the waves. Beach sediments can also be augmented by human activities such as beach nourishment (dumping of sand or fertilizer).
The sand in a beach is not fixed; it constantly moves, either accumulating on the surface or being eroded by waves and currents. This movement is accelerated by the presence of coralline algae, which create a sand-like matrix. These areas are known as biogenic reefs.
When sand is blown by the sea breeze, it forms small hummocks or ridges, which are known as dunes. When a beach has a large supply of sand, it can develop several rows of dunes. Beaches also form sandbars, which are narrow areas of sand that extend from the beach into deeper waters. The shape of a beach can also be affected by the tides and season. For example, in winter storm winds can erode beaches and create sandbars. Then, in summer, the waves may retrieve sand from these sandbars and rebuild the beach.
Because beaches are always changing, they provide a habitat for many different organisms. From tiny hermit crabs scurrying across the sand to colorful fish swimming in the water, the beach is home to a vast array of fascinating life. Beachgoers can help to protect and sustain these natural ecosystems by reducing beach pollution, such as trash, cigarette butts and plastic. They should also leave wildlife alone and not take anything from the beach, such as sea plants or animal shells. Doing so protects birds from choking on floating litter and prevents animals that live in the tide pools from finding their food.