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.
what are rock falls?
suddenly when pieces of rock from a weathered cliff fall. This often occurs when the rock at the base of the cliff has been undercut by the waves leaving the rocks above unsupported causing them to fall
what is slumping?
occurs after heavy rainfall The rain seeps into permeable rock. At the junction where the permeable rock meets the impermeable rock the saturated soil and weakened rock slumps and slides along a curved surface.
what is sliding?
large amounts of soil and rock move downslope rapidly. along a flat surface.
what is the land at beach head used for?
farming because the chalk is permeable
what is attrition?
materials carried by the waves bump into each other and so are smoothed and broken down into smaller particles.