A beach is a zone of sand, stone, and gravel along the shore of a body of water. The term is most often associated with the ocean, but beaches can also form on a lake or river shoreline. Beaches are constantly changing, and the materials that make up a beach are transported from one place to another by waves and tides. Beaches are a habitat for many different marine organisms, from tiny hermit crabs scurrying across the sand to sea anemones hiding beneath the surface.
In general, beaches are created by the erosion and transport of sediment from a source area. This process is most active during storms, when waves are larger and have more energy. This can result in the removal and transportation of large amounts of beach material in a very short period of time. Following a significant storm, most beaches go through a period of recovery to regain the cross-sectional profile that they had prior to the event.
The sediment that makes up a beach may be either terrigenous (originating from the underlying rock) or biogenic (originating from the breakage of skeletal parts, such as shells or coral, accumulation of frameworks built by organisms secreting a hard skeleton, or biochemical precipitation of carbonate). Beaches are constantly being formed and eroded, with new materials arriving and old ones being carried away. The composition of a beach can be determined by its color; light-colored sands are terrigenous, while dark-colored sands are biogenic.
Beach erosion is usually caused by a combination of processes, including attrition, which is the grinding of rocks and sediments together; abrasion, which occurs when rocks rub against each other; hydraulic action, which is the pushing of water into cracks; and corrosion, which involves the chemical breakdown of metals and minerals. The sediments that make up a beach are usually subjected to the forces of erosion and transport for long periods of time, resulting in the formation of ridges that slope down to the water’s edge.
In addition to their recreational value, beaches are important natural areas for the conservation of biodiversity. Beaches provide habitat for various animals, from hermit crabs and fish to sea anemones and birds. They also serve as the source of food for a number of marine species, such as shrimp and lobster.
Many people enjoy going to the beach to relax and have fun in the sun. However, there are some things you should be aware of before visiting a beach. For example, beaches can be polluted by garbage and waste washed in from inland. These pollutants can include sewage, oil and other toxic chemicals, and even human waste from landfills. This is why some beaches are closed after heavy storms. In addition, beach pollution is often a problem in urban areas, where waves and drainage pipes can carry toxins from sewage treatment plants to the ocean. Some scientists are working to find ways to reduce urban beach pollution and improve beach water quality.