How Beaches Are Shaped and Characterized
A beach is a landform alongside a body of water that consists of loose, sedimentary material. This material may be composed of any of the six major size classes of rock, namely clay, silt, sand, pebbles, cobbles and boulders. Sediments settle in different densities and structures, creating a variety of textures and colors along beaches. Beaches are always changing, building up during periods of accretion and eroding during periods of erosion.
The sand grains that make up a beach are often light in color due to the quartz and feldspar minerals that form them. Many beaches are also characterized by an iron-stained (oxidized like rust) color that is caused by brown-stained shells that have broken down and mixed with the quartz sand grains. The sandy coloration of some beaches is given a sparkle by mica, which makes up less than one percent of the beach sand.
Because of their natural beauty, beaches are popular with humans and have been used for recreation and relaxation since ancient times. In the United States, commercial sea bathing grew in popularity during the 19th century. In addition, beachfront properties became desirable as the middle class gained wealth and leisure time. By the end of the 19th century, oceanography and geology were better understood, and beachfront properties were surveyed to assess their suitability for recreational use.
Coastal erosion is the most important factor that influences the shape and character of beaches. Erosion usually occurs on a beach either due to high winds, low tides or storm surges. During periods of calm weather, however, the beach can build up as the result of wave-induced sediment transport. Beaches are also subject to erosion by human activity, especially when the construction of buildings or other developments is done close to the shoreline.
As waves roll over the ocean floor, they push sediment up from the continental shelf and onto beaches. This process is called longshore transport and it can significantly change the shape of a beach in a very short period of time. In addition, wind-driven sand blowing from offshore can also affect the shape and character of a beach by adding or subtracting sand from its shoreline.
A sandbar is a narrow, partially exposed ridge of sand or coarse sediment built up by waves offshore from the beach. Sandbars may serve as shallow habitats for marine organisms, signal changing tides or simply provide a safe place for swimmers to enter the water.
Beaches are always changing, building up or eroding, and the type of sand on the beach is determined by many factors, including the strength of the winds, the depth of the water and the presence of rocks near the beach. The size of the sand particles that make up the beach, and its color, are also influenced by the amount of sun it receives.
In addition to being a beautiful place for recreation, a beach can be an important habitat for birds, marine plants and animals. In order to preserve these species, it is vital that beachgoers respect the wildlife and avoid removing materials from the beach, such as shells, ropes or twine. In addition, reducing beach pollution is also important because it can prevent marine life from finding food or shelter.