A beach is an area of land that is sloping gently into the ocean. Its material consists of sand, pebbles, rocks, and seashell fragments. These materials are created by weathering over time. Water and wind wear away the land, and waves break up the hard pieces into sand. In some areas, huge boulders are eroded down to tiny grains of sand.
There are three types of beaches. One type is a reflective beach, which is characterized by an upwardly concave nearshore zone and relatively fine sand. It may also feature a steep (4-10 deg) beach face where waves break. In addition, waves may have cusps, which are formed by the interaction of incoming and reflected backwash.
Materials on the beach are often carried long distances by wind and waves. This ocean sediment may be composed of sand, shells, and seaweed. This material is carried many kilometers by ocean currents. This process alters beaches every day. However, the process of erosion can make it difficult for the plants and animals to survive on the beach.
Storms cause the sand on a beach to shift. During winter, storms send sand into the air and erode beaches. These storms also cause sandbars, narrow areas of exposed sand. The waves then retrieve this sand and build up the beach during summer. These seasonal changes lead to changes in the profile of a beach, making it steeper in the winter than in summer.
The composition of a beach is influenced by the type of sediments that lie upstream. Wind and waves cause sediments to move, and the size and compaction of sediments determines how quickly they will erode a beach. If sediment is compacted, it is more resistant to erosion. In contrast, sediment that is in suspension is subject to erosion by longshore currents.
Active beaches have a complex profile. It varies according to wave parameters, sediment composition, and tide height. These active beaches often feature a low-tide terrace or a series of ridges and berms, as well as a steep frontal slope. During periods of high tide, erosion can cause these steep crests and berms to form.
Beach nourishment activities are crucial to maintaining the health of the beach. These activities must ensure that new sediments are compacted before they become exposed to erosion. Otherwise, the new sediments may wash away or be eroded before they have a chance to integrate into the established vegetation. Moreover, these newly-formed sediments may introduce flora and fauna.
A beach ladder or board-and-chain is one way to maintain an accessible beach. These structures have planks laid close together perpendicular to the direction of traffic flow. They are then secured by a cable or chain. These structures are commonly used as light-duty vehicular access ways or pedestrian pathways along the coast.