A beach is the narrow strip of land along a body of water. While this land is typically made up of sand or pebbles, it can also contain other materials like rocks, mud, and shells. Beaches are found in oceans, lakes, rivers, and even some large ponds. They are very popular places for people to spend their time, and many beaches provide recreational activities such as swimming, sunbathing, building sandcastles, and playing sports. Beaches are always changing and evolving, and their appearance is determined by many factors, including erosion.
While erosion is often seen as a negative force that decreases the size of a beach, it can actually increase its size in some cases. Beaches may grow when waves carry sediment inland and deposit it on the beach. Some beaches can also experience growth if they are located near river deltas where rivers carry eroded material to the ocean. Beaches can also grow if they have protected areas, such as spits, that protect the beach from powerful waves and winds.
Erosion is a constant process that works to move loose materials such as sand and pebbles toward the shoreline. As the movement of these materials is influenced by various weather conditions, beach erosion can happen quickly or slowly over time.
As the movement of these materials continues, erosion can create different beach zones known as the swash zone, beach face, wrack line, and berm zone. The zones are characterized by the type of particles they contain, with coarser materials closer to the water and finer materials farther inland.
Beaches may be created in different ways depending on the area they are in, and they can be made up of any material that erodes easily and is capable of being carried by the waves. These material can include sand, gravel, cobbles, and pebbles. Beaches are often colored white, black, tan, or yellow, but their color can be influenced by the type of rock in the surrounding area.
One of the most common elements of a beach is a sandbar, which is a submerged or partially exposed ridge of sand that is built up offshore from a beach. Sandbars are the result of swirling turbulence in the sand caused by the breaking waves. The turbulence excavates a trough in the sandy bottom, and some of the sand is deposited on the offshore flank of this trough. Sand suspended in the backwash or rip currents adds to this bar, as well as any sand that has been washed ashore from deeper waters.
As the wave erodes the bar, it can become gradually larger until eventually it covers the entire width of the beach. This is the classic beach profile, which can be observed at many southern California and European beaches. This profile changes seasonally due to the difference in the amount of wave energy during the summer and winter in these areas. The higher wave energy of the summer season tends to bury more sand near the beach berm and dune, while the lower wave energy of the winter causes less sand to get deposited.