A beach is a stretch of sand or other granular material along the shore of a body of water. It is most often used to refer to a sandy ocean shoreline, but beaches also occur by lakes and alongside rivers. Beaches consist primarily of sediments, which are fine to coarse sized fragments of rock that have been moved by waves and wind. These sediments may include clay, silt, sand, gravel, cobbles, pebbles, and even boulders.
Beaches are constantly changing as they form, grow, and erode. Over time, erosion is the process by which flowing water wears away rocks and deposits them in a new location. Erosion can happen naturally or through human activities, such as building construction, dumping fill in the sea, or removing vegetation that protects the shoreline from erosion.
The term beach is sometimes used to refer to the entire coastal zone, including dunes, marshes, and other natural features. But more usually, it refers to a narrow strip of land directly where the water meets the land.
Beaches are not just beautiful places to relax, but they are also home to a wide variety of animals and plants. From hermit crabs scurrying across the sand to colorful fish swimming in the surf, the shore is teeming with life. Beaches are important habitats for birds, insects, and marine mammals. They are also the source of sand for erosion, the place where sea turtles lay their eggs, and the site for many plant species such as dune grasses and sea weeds.
The composition of a beach depends on the nature and quantity of the sediments that it is made from, as well as on their particle size, state of compaction, and velocity of flow. The most common sediments found on beaches are sand, silt, and clay. Sand and silt, which are the smallest particles that make up a beach, are carried forward by waves and currents; clay is carried backward by the same forces. The turbulence of breaking waves excavates the troughs that form bars, and the swirling sand in rip currents adds to a bar’s top.
A cusp is a small ridge or hill that forms on a beach between the horns (crests) of wave breaks, and the embayments (troughs). Cusps gain or lose sand by their interaction with changing waves, and they are therefore ephemeral. The sudden appearance and disappearance of cusps is one of the mysteries of a beach.
Beaches are affected by both natural and human forces. Direct human impacts are the result of bad construction practices, while indirect human impacts are caused by water pollution, beach nourishment, climate change, and sea level rise. Beaches are important habitats for wildlife, so it is important that people respect their environment and leave animals alone. Reducing beach pollution is also essential; plastic trash can choke marine creatures, and it prevents algae and sea plants from growing. It’s also important to avoid picking up seaweed or shells; this takes valuable resources out of the ecosystem.