An accumulation of sand and gravel found at the landward margin of the sea or a lake. Along sea coasts, beaches comprise the backshore zone (above mean high water) and the foreshore zone (between mean high and low tide levels). The angle of slope and the sedimentary structures of a beach are related to the grain size of the beach materials, and to the nature of wave activity and other sedimentary processes active in the area.
An accumulation of sediment deposited by waves and longshore drift along the coast. The upper limit is roughly the limit of high tides; the lower, of low tides. The beach classifications dissipative and reflective seem to have fallen out of favour, but see Sherman and Bauer (1993) PPG 17 if necessary. See also drift-aligned beach. Almeida et al. (2011 ESPL 36, 4, 523) show a clear relationship between offshore wave height, and the beach profile. They reveal three thresholds for morphological change: waves higher than 2.3 m are responsible for important changes to the berm and beach face; waves higher than 3.2 m are responsible for important changes to the sub-tidal terrace and long-shore bar; and waves over 4.1 m are needed to effect morphological change further seaward, near the depth of beach closure.
Beach
- focal area
- focal distance
- focal length
- focal mechanism, earthquake
- focal plane
- focal point
- focal ratio
- focal reducer
- focal surface
- Foch, Ferdinand (1851–1929)
- Fock degeneracy
- Fock, Vladimir Alexandrovich
- focus
- focusing
- focusing((in animal physiology))
- focus, optical
- focus, orbital
- fodinichnia
- Fodor, Jerry Alan (1935–2017)
- foehn wall
- foehn wind
- foetus
- fog
- foid
- foidolite