A beach is a landform consisting of ocean sediment. These particles may be sand, gravel, cobbles, or even boulders. Beaches change every day, with tides and waves bringing in new materials and taking away others. Beaches are also the main habitat for a variety of marine organisms such as crabs and sea anemones.
The term beach applies to a wide range of geological formations, from the sandy beaches common in Europe and North America to rocky or coral-rich shorelines found throughout the world. Each type of beach has its own specific characteristics, but all beaches have one thing in common: They are dominated by the action of waves on exposed coastlines.
Coastal sediments are the primary building blocks of all beaches. They are characterized by their granular size, with coarse sand (>1 mm), gravel (2-4 mm), pebbles (4-64 mm) and cobbles being the most common beach materials. These sediments are deposited by wave-driven currents, and can be either resuspended or depositionally stabilized by structures such as groynes.
Because beaches are highly dynamic, they can experience extreme changes in their shape and composition within hours. Well-stabilized foreshore areas will accrete, while unstabilized areas will erode. Beach nourishment activities such as dumping inlet sand, spreading beach rakes or placing concrete blocks in the water help to stabilize beaches. However, the placement of these materials must be carefully planned to ensure that the resulting sediments have sufficient time to compact and establish vegetation before aggressive wave or wind erosion can occur.
The beach as a place for relaxation and pleasure has long been a popular attraction. During the 19th century, commercial sea bathing spread to the United States and parts of Britain and was made more accessible with the development of railways such as Henry Flagler’s Florida East Coast Railway. Many beaches are today crowded with recreational and leisure activities, from sunbathing to swimming and surfing.
Beaches are home to a variety of wildlife, from insects and crabs to birds and sea turtles. Some species nest in sand dunes, while others lay their eggs on the beach. Some specialized beaches, such as sandbars and barrier islands, are home to endangered plants and animals.
Due to human activity, some beaches are heavily polluted. Waste from cities and towns, including raw sewage and chemicals, wash up on many beaches after storms. Plastic waste and trash from people’s picnics can also be found on beaches. Many beach ecosystems are sensitive to these pollutants and can be greatly affected by their presence. In some cases, beaches are closed after high levels of pollution are detected. As a result, many countries have implemented laws to protect beach ecosystems.