Deposition Landforms
Characteristics and formation of
beaches, spits and bars. If rocks and cliffs are being continually weathered, eroded and moved then it stands to reason that this will generate a lot of material that will need to be deposited (or laid down) somewhere else along the coastline. The major deposition landforms are beaches, spits and bars. Deposition occurs when wave velocities slow, or when ocean currents slow due to encountering frictional forces such as the sea bed, other counter currents and vegetation.
Beaches are areas of sand, pebbles and shingle that
are formed by deposition produced by wave processes.
Gently sloping beaches are formed by strong destructive waves that backwash more
material away from the beach that they swash up the beach.
Steeply sloping beaches occur by constructive waves that swash more material up
the beach than they backwash away, building up a steep beach gradient.
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Think about it! 1) Try this landforms identification exercise 2) Try these quizzes from Fife education 3) Try this nice coastal features quiz 4) Coasts questions from s-cool.co.uk 5) Have a go at my Hot Potatoes crossword 6) Half a minute coasts quiz from juicy Geography 7) Coasts penalty shoot out game from juicy Geography 8) Have a try at finishing this passage on Coastal Deposition |
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Above is
Spurn head,
one of the many famous spits found around the UK coastline.
Spits are created by the process of Long shore drift. Some eroded material
ends up caught up within the waves and is carried by the sea along the coastline
in cells known as littoral cells. Material is carried along the shore in a
zigzag fashion by waves as they swash material up the beach at an angle and
backwash material down the beach at a right angle.
Wherever there is a break in the coastline (e.g. across a river or a change in
coastline direction) then material is deposited closest to the shore.
Eventually this material builds up
out into sea to form a spit. As seen in the picture opposite of Spurn Head Spits often have salt marshes build up behind them because the spit offers protection from the stronger waves and the wind, allowing salt tolerant plants to grow. If a spit extends from headland to headland then a bar will be created. You can see this process on an animation at this link. |
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