revision notes on coasts for the aqa specification geography gcse

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Breakdown of rocks where they are, erosion when rocks are broken down and carried away by something
Mechanical weathering ­ breakdown of rock without changing its chemical composition
Freeze thaw weathering ­ when temperatures alternates above and below 0 degrees, water gets into
cracks, when water freezes it expands which puts pressure on rock, when water thaws it contracts which
releases pressure on rock, repeated freezing and thawing widens crack and causes rock to break up
Chemical weathering ­ breakdown of rock by changing chemical composition
Carbonation ­ rainwater has carbon dioxide dissolved in it makes weak carbonic acid, carbonic acid reacts
with rock that contains calcium carbonate- so rocks dissolved
Mass movement ­ shifting of rocks and loose material down a slope ­ happens when the force of gravity
acting on a slope is greater than the forces supporting it
Mass movement causes coasts to retreat rapidly
More likely to happen when soil saturated water acts as a lubricant
Need to know about slides when materials shifts in a straight line
Slumps are when material shifts in a rotation
Rockfall ­ fragments of rock break away from the cliff face often due to freeze-thaw weathering
Landslide ­ blocks of rock slide downhill
Mudflow ­ saturated soil and weak rock flows down a slope
Rotational slip ­ slump of saturated soil and weak rock along a curved surface
Barton on Sea ­ Cliff Collapse Case Study
In Hampshire/Dorset ­ near Christchurch and Limington
Cliff collapse ­ caused by prevailing wind, rock structure of permeable sand on top of impermeable clay
leading to water pooling and heavy saturation of soil so it is very heavy causing more pressure, bunnies-
local streams that go into soil
Waves are formed by wind blowing over sea and causing friction with the water therefore causing ripples
which develop into waves
The longer the fetch the more powerful the waves
Waves can also be formed by earthquakes and volcanic eruptions under the sea

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In open sea not much horizontal transfer of water but as reach the coast making the usual circular motion
of the water increasingly oval.…read more

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Longshore drift ­ the transport of sediment along a stretch of coastline caused by waves
approaching the beach at an angle( waves approach the beach and go up at an angle (swash), then
go back down vertically at right angles to the edge of the shore (back wash) , making a zigzag
motion which moves sediment along it)
Size and quantity transported depends on strength of the waves and tidal currents
In storms quite large pebbles can be flung up out of beach which can…read more

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It has a recurved tip at the end
Material is deposited, at the end of a headland or where the coast changes direction in the direction
of the prevailing wind dramatically, by long shore drift. The tip of the spit is pushed in the direction
of the temporary wind or current
Stretches out in a SE direction
Made of shingle
Salt marshes
1. Deposition and accumulation
2. Mudflats created
3. Pioneer species ( plants that are salt tolerant) begin to emerge
4.…read more

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The area is closely monitored and managed to maintain its biodiversity access is limited and
development is restricted
Hard engineering is artificial structures, sea walls groynes rock armour, expensive, high maintenance,
interfere with natural processes, not that attractive
Soft engineering is trying to fit in and work with natural processes, lower key, beach nourishment dune
regeneration managed retreat (marsh creation, cheaper, low maintenance, more sustainable
Managed retreat allowing controlled flooding of land of relatively low value and allowing it to form a salt
SMP…read more

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County councils have to work together
Funding for sea defence strengthening may come from government…read more


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