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Coasts (Erosional Landforms (Arch- overtime erosion may lead to 2 back to…
Coasts
Erosional Landforms
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Stack- gradually the Arch is enlarged by erosion, at the base and by weathering processes acting on the roof. Eventually The roof will be worn away and collapse to form an isolated pillar of rock known as a stack.
headland- The tougher, More resistant bands of rock are eroded much more slowly. They stick out into the seat for headlands. Most erosional landforms are found here.
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bay- different types of rock at the coastline will be eroded at different rates. Weaker bands of rock erode more easily to form bays.
wave cut platform- through a continual sequence of wave cut notch formation and cliff collapse, The cliff will gradually retreat. In its place will be A gently sloping rocky platform called a wave cut platform .
Depositional landforms
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Sand dunes
Sand dunes are formed when sand is blown inland by onshore winds, which over time builds up to create sand dunes.
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Bars
And off shore bar forms further out to sea, waves approaching a gently sloping coast deposit sediment due to friction with the seabed. The buildup of sediment offshore causes waves to break at some distance from the coast
Waves
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Erosion
hydraulic action-This is the power of the waves as they smash onto a cliff. Trapped air is forced into holes and cracks in the rock eventually causing the rock to break apart. The explosive force of trapped air operating in a crack is called cavitation.
Solution-The dissolving of soluble chemicals in rocks, e.g. limestone,
abrasion-This is the 'sandpapering' effect of pebbles grinding owr a rocky platform often causing it to become smooth
attrition-Rock fragments carried by the sea knock against one another causing them to become smaller and more rounded.
Transport
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process
long shore drift- If waves approach at an angle the sediment will be moved along the beach in a zigzag pattern
The movement of sediment on the beach depends on the direction that waves approach the coast. Where waves approach head-on, sediment is simply moved up and down the beach
Subaerial Processes
weathering
Mechanical (physical) weathering- the disintegration (break up) of rocks. Where this happens, piles of rock fragments called scree can be found at the foot of cliffs.
Biological weathering- due to the actions of flora and fauna. Plant roots grow in cracks in the rocks. Animals such as rabbits burrow into weak rocks such as sands.
Chemical weathering- caused by chemical changes. Rainwater, which is slightly acidic, very slowly dissolves certain types of rocks and minerals.
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