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coasts EQ2 - Coggle Diagram
coasts EQ2
depositional landfordms
spit
beach extends off a headland. caused by LSD. buildup of sedument over time at end of coastline, into a bay. Equilibrium is reached so therefore the build of of sand protrudes from under the ocean water.
durlston head, SW England
bayhead beach
beaches found in bays. Produced by material deposited from constructive waves. swash has strength to wash them up the beach, but has a weak backwash. so deposits the material. wave refraction takes place here
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tombolo
these are bats that connect two landscapes together - for example, a mainland area to an island area that are not already joined.
portland bill, SW england
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hooked/ curved spit
this is a spit (formed by the same process as above) that has a curved end landwards, into a bay. the hook forms due to wave refraction, or because the prevailing wind changes direction over time
calshot spit, southampton
cuspate foreland
low lying, triangular shaped headlands, extending out from a shoreline, formed from deposited material. caused by LSD occuring in two opposite directions either side of the cuspate foreland, creating a triangular shape.
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sediment cells
a sediment cell is a linked system of sources of material, transfers of that material, and the sink of it along a coast.
the sediment cell system is an example of a dynamic equilibrium system - a balance between the material in the cell being added, moving, and being removed
examples of inputs - cliff erosion, onshore currents, river transport, wind blown sediment, subaerial processes, marine organisms.
examples of transfers - longshore drift, swash, backwash, tidal currents, ocean currents, wind
examples of sink - backshore landforms (e.g. sand dunes), foreshore landforms (e.g. beaches), nearshore landforms (e.g. bars), offshore landforms (e.g. barrier islands)
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processes of weathering.
weathering is the breakdown of rock in situ (one position, without movement).
physical (mechanical)
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e.g. Freeze thaw (water in crack of rock, freezes and expands, further cracking rock etc.)
e.g. salt crystal growth (salty sea coasts, water gets into porous cracks in rock, pit pressure on its structure and slowly break it down).
e.g. wetting and drying processes (clay) repeatedly expands and contracts the rock leading to crumbling effect.
chemical weathering
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carbonation: carbon in limestone is affected. When reacting with rainwater, the rock dissolves.
hydrolysis: breakdown of minerals to form new minerals (e.g. carbon dioxide attacking feldspar (pinky) minerals in granite.
oxidation: the addition of oxygen to minerals, increasing rock volume, causing rock breakdown. sandstones and shales are particularly vulnerable.
biological weathering
tree root weathering: seeds falling into cracks in rock, germinating, and forcing the rock apart.
rock boring: some animal species can bore into rock, particularly softer rock.
rockfall
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freeze thaw weather, salt crystals, hydraulic action, abrasion etc. all weaken rock material and can cause rock fall
cliffs more prone to rockfall generally have: a structure that has many joints and faults. steep cliffs. are in earthquake prone areas.
landslides
a landslide is the downslope movement of blocks of rock down a relatively flat slip plane, maintaining contact with the cliff surface throughout.
chemical weathering causes well jointed rock such as limestone to weaken. gravity then pulls to loosen tock downward.
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rainstorms can encourage landslides, adding weight and moisture to the land
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mass movement
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it includes landslides, rotational slumping and rockfall
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cave arches stacks and stumps - old harry, swanage