A beach is a wide area of sand or gravel (or sometimes silt) along the shore of a sea or lake. Beaches have many natural and human features that make them interesting places to visit.
The composition of a beach depends on the nature and quantity of sediments upstream of the beach, the speed and turbidity of the water and wind, and the compaction state of the sediment. Sediments that are more densely packed and compacted resist erosion by waves and wind better than looser sediments, and vegetation can also help protect beaches from erosion by slowing the flow of water and reducing the intensity of wave action.
Most of the sand on a beach is moved south by longshore drift, a natural process. This happens as powerful swells and waves hit the shore and, in some cases, break near beaches. In addition, sand can move from beaches into the surf zone before the waves break and even offshore to areas called sandbanks. This ongoing movement of sand is one of the primary reasons that beaches change over time.
Beaches are found around the world, and most have a large variety of natural features. Some are wide and sandy, others narrow and rocky. There are also beaches with a high shell content, and those that have no shells at all. Beaches can be very steep, or they may have a gradual slope. Beaches often have a trough, a dune or a bar that extends from the trough to the sea.
Some beaches are covered in sea water at all times, and some only at certain stages of the tide. The rise and fall of the sea level are controlled by the gravitational pull of the Moon and Sun, and these forces are reflected in the shape of the beaches on our coastlines.
A beach can be made of any type of material, but sand is the most common. It can be white, black, tan or yellow, depending on the geology of the region and the types of rocks that provide the sediments for the beach.
Beaches are formed by a combination of processes, such as attrition, which is when the rocks rub together; abrasion, in which the rocks are broken up into smaller particles by waves; and hydraulic action, in which water is driven into cracks. In order for a beach to form, there needs to be relatively soft rock that erodes faster than the harder rock beside it.
Beaches are often sheltered by dunes, and this protection can help to preserve their habitats. Many species of birds, fish and animals depend on beaches for breeding, feeding and shelter. Beaches are also very important for sea turtles, which lay their eggs there. The loss of a beach could lead to the extinction of these creatures. In addition, the beaches are a great place for people to relax and enjoy nature. Many towns and cities have beaches that are used by local residents and tourists.