Coasts Flashcards
what is the crest of a wave?
the top of the wave
what is backwash?
the movement of water and load back down the beach.
what is velocity?
the speed the wave is traveling at.
what is velocity influenced by?
wind, fetch and depth of water
what is the trough of a wave?
the low are between two waves.
what is the wave height?
the distance between two crests or two troughs
what is the wave frequency
the number of waver per minute
how are waves caused?
by wind blowing over the sea
what is wind strength?
the stronger the wind, the greater the friction, the larger the wave.
what is wind duration?
the amount of time the wind has been blowing
what is fetch?
the distance of open water over which the wind has been blowing. the longer the fetch the more powerful the wave.
what are constructive waves?
less energy and encourage deposition. Low in height ad widely spaced. Swash is stronger than the backwash. calm weather
what are destructive waves?
strong winds blown over large fetch areas. powerful ad lead to coastal erosion.
example of mechanical (physical) weathering?
freeze thaw
what is freeze thaw weathering?
the repeated freezing and thawing of water in joints in a rock. wen water freezes it expands by about 10% putting pressure on the rock. when the ice melts it seeps deeper into the rock. after repeated cycles fragments of rock start to break off.
example of chemical weathering?
acid rain
how does acid rain weather rocks?
when rain falls on rocks such as limestone a weak chemist reaction takes place causing the rocks to weaken and breakdown.
what is biological weathering?
when roots, burrowing animals and nesting birds get into the cracks they widen them causing the rock to weaken and decay.
what is mass movement?
the downslope movement of rocks and soil from the cliff top under the influence of gravity.