What Is a Beach?
A beach is a landform alongside a body of water that is comprised of loose rock particles (sand, gravel, shingle and pebbles) which have accumulated from wind-driven waves or currents. These loose materials may come from eroded rock offshore or from coastal erosion resulting from slumping headlands or natural processes such as coral reef accretion. The types of sand at a beach depend on local geologic conditions, especially the type of rocks that are exposed in the shoreline. In addition, the color of sand at a beach is dependent on its source. For instance, quartz and feldspar create light brown sand while sedimentary rock with high amounts of iron oxide such as metamorphic or igneous rock produces reddish-brown sand.
Over long periods of time, well-stabilized foreshore areas tend to accrete, while unstabilized areas will erode. However, freak wave events such as tsunami, tidal waves and storm surges can substantially alter the shape, profile and location of a beach within hours.
Beaches are influenced by human activities as well. Clearing vegetation for farming and residential development changes surface wind patterns, increasing the rates of erosion and changing the character of underwater flora and fauna in coastal shallows. Beaches are also impacted by pollutants from runoff and storm debris.
Sandy beaches occupy about one third of the world’s coastline and are very popular for recreation such as swimming, fishing, surfing and diving. They often have facilities such as lifeguard posts, sand volleyball courts and showers. In many cases, these recreational beaches are vital to the economies and cultures of the communities they serve.
A beach bar is an isolated sand ridge in deeper waters off a beach formed by the swirling turbulence of wave breaking over the top of a sandy beach. Sand from a nearby beach is deposited into the trough, while sand suspended in backwash and rip currents adds to the bar. A sandbar in deeper water may be connected to a beach by a reef or rocky platform.
Beaches can be extremely polluted from a number of sources. Wastewater from cities and towns often washes ashore, as do plastic bags, cans and other containers used at picnics. In addition, toxic chemicals and sewage can wash up from inland rivers that flow to the ocean. This pollution has led to the closure of some beaches after strong storms.