Beach

Beach is a subject to wave action at the shore of an ocean or lake. Most of the sediment making up a beach is supplied by rivers or by the erosion of highlands adjacent to the coast. Beaches extend from a low waterline landward to a definite change in material or physiographic form, such as the presence of a cliff or dune complex marking a clear demarcation of the edge of a coast . The surf zone is the area between the landward limit of the waves and where the farthest seaward wave breaks. Water motion landward and seaward across the foreshore is called swash and backwash, respectively. The foreshore's slope angle is related to the size of the beach material and the vigor of the waves.

The sand deposit may extend well inland from the berm crest, where there may be evidence of one or more older crests (the storm beach) resulting from very large storm waves and beyond the influence of the normal waves. At some point the influence of the waves (even storm waves) on the material comprising the beach stops, and if the particles are small enough (sand size or smaller), winds shape the feature. Where wind is the force distributing the grains inland, the deposit behind the beach becomes a dune.

These geomorphic features compose what is called the beach profile. The beach profile changes seasonally due to the change in wave energy experienced during summer and winter months. The beach profile is higher during the summer due to the gentle wave action during this season. The lower energy waves deposit sediment on the beach berm and dune, adding to the beach profile. Conversely, the beach profile is lower in the winter due to the increased wave energy associated with storms. Higher energy waves erode sediment from the beach berm and dune, and deposit it off shore, forming long shore bars. The removal of sediment from the beach berm and dune decreases the beach profile.