The composition of a beach depends on the sediments that lie upstream of it. Waves and wind move these sediments, which are classified according to particle size and level of compaction. Compacted sediments resist erosion, while loose sediments are more likely to be washed away by longshore currents. The composition of a beach is also affected by established vegetation, which slows down the fluid flow at the surface layer.
Sandy beaches occupy approximately one third of the world’s coastline and play a major cultural and recreational role, often driving local tourism industries. Some of these beaches are well-developed, with facilities like lifeguard stations, showers, and changing rooms. They may even include housing and hotels. But they aren’t the only types of beaches.
Beaches can be sandy, muddy, or rocky. Sand and other sediments that make up a beach are formed through erosion of rocks and coral reefs. Typically, a beach is a narrow, gently sloping strip of land. The shoreline is composed of loose rock, sand, and rock fragments. Most of these materials are the result of weathering, a process that takes many years to take place. The forces of waves pounding the coast can wear down massive boulders to tiny sand grains.
Large cyclonic storms can also affect a beach. These storms usually involve strong waves and high tides. During a large storm, the waves can be so strong that they overflow the sand dunes and erode the beach. During such storms, the resulting sand on the beach is often shifted and redistributed. It’s crucial to note that there is no single cause of erosion, and a beach’s history reflects a complex series of forces.
Sand is made up of two types of minerals. In temperate climates, sand is made up mainly of quartz and feldspar. In tropical areas, however, sand is made up of skeletal remains of marine organisms and calcareous sediments. They can also form ridges that parallel the shore and may be broken by wind.
Beaches are also home to many animals and plants. Sea grasses, sea turtles, crabs, and insects all depend on the sand for their sustenance. Some of them also lay their eggs in the sand. The majority of the sand on a beach is made up of small particles of weathered quartz from the Appalachian Mountains.
Beaches can also help keep water clean by filtering coastal runoff. Runoff deposited in rivers and drainage pipes can contain sewage and toxic chemicals. The runoff is then deposited into the sea, where it can cause erosion. The debris that is washed into the ocean may harm animals or birds. This can result in the loss of valuable habitat for marine animals.
Beach nourishment can also be an effective way to combat erosion and improve the habitat for selected species of biota. Beach nourishment can be implemented as a series of small additions of sand every year, or in one major episode.