The beach provides recreational opportunities to millions of people, including swimming, boating, and fishing. People also enjoy sunbathing and beachcombing. Beaches also protect coastal communities by acting as buffers against high winds. In addition, beaches are an important economic resource. Ocean beach recreation is one of the fastest-growing outdoor activities in the U.S. However, beaches are also plagued by problems like marine debris and pollution.
Beaches are often characterized by different types of sand, depending on where they are located. Coarse sand is typically deposited on a beach along the coast, while fine sand is located farther inland. The composition of fine-grained sand is determined by the energy required by the waves to move the sand. Sand composition is typically coarser during the winter than during the summer.
The profile of an active beach is dependent on several factors, including the sediment composition, wave parameters, and tide height. A typical beach profile has a concave shape and slopes gently toward the body of water. Some beaches also have narrow sediment barriers, separated from the open ocean by tidal inlets.
Besides sand, a beach can also include rock fragments, pebbles, and seashell fragments. These materials are made of sediments that were washed ashore from ocean waves. Generally, these materials are weathered, which means they were eroded by wind and water over many years. For example, huge boulders that once formed the shoreline have been worn down to tiny grains of sand.
The structure of a beach is a complex system of layered surfaces. The top layer is composed of fine sand and is capped by a steep, concave-upshore zone. Below this zone, a layer of sediment with varying grain sizes accumulates as a coarser step. The resulting beach face is often capped by a steep berm or beach cusp.
The sediment that makes up a beach varies greatly from beach to beach. Some are extremely fine, while others are made of medium or coarse sand. In addition to sediment, beaches are also characterized by their size and shape. Some beaches are steep, while others are wide and gentle. They may contain significant amounts of shells or very little. The width of a beach may vary over time, which can reflect the forces of nature. Exploring a beach will also reveal a variety of other features, including rocks, tree stumps, and outcrops of mud layers.
One of the most prominent threats to a beach’s future is natural coastal erosion. This process is accelerated by weather systems, such as the El Nino-Southern Oscillation. This weather system can affect the beaches of many oceanic islands, making them vulnerable to erosion. In Tuvalu, beaches were retreating rapidly in the 1990s, which scientists traced back to the weather system.
Another danger to a beach is rip currents. The best way to avoid a rip current is to swim close to a lifeguard or in an area designated by a lifeguard. These areas are often marked with a yellow or red flag.