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What is the backshore?
The area between the high water mark (HWM) and the landward limit of marine activity.
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What is the foreshore?
The area between the high and low water marks. (The most important area for marine processes in non-storms).
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What is the inshore?
The area between the low water mark (LWM) and the point where waves stop influencing the land beneath them.
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What is 'offshore'?
The area beyond the inshore limit. (Activity limited to the deposition of sediments.)
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What is fetch?
The distance over open sea that a wind blows to generate waves. the longer the fetch, the greater The potential for large waves.
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What are the inputs to the coastal system?
Energy to drive the system, sediment, changes in sea level, human activities.
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What are the outputs to the coastal system?
Coastal landforms (erosive and depositional), accumulation of sediment above the tidal limit, the loss of wave energy.
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How does a wave form?
Waves are created by wind blowing over the surface of the sea. As the wind blows over the sea, friction is created - producing a swell in the water. The energy of the wind causes water particles to rotate inside the swell, moving the wave forward.
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What is swash?
The rush of water up a beach.
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What is backwash?
The movement of the water back down a beach.
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What are the characteristics of constructive waves?
Created in calm waters. They have a long but low wavelength, and a low frequency - about 6-8 per minute. They break on the shore, and have a strong swash and a weak backwash.This pushes material up the beach.
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What are the characteristics of destructive waves?
Created in storm conditions. Short wave length and are high and steep. They have a high frequency - about 10-14 per minute. Stronger backwash than swash, eroding the beach,
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What are tides?
A periodic rise and fall in sea level, caused by the gravitational pull of the moon. The moon pulls water towards it, creating high tide, and a compensatory bulge at the other end of Earth, The area between the two bulges is the point of lowest tide.
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What is the 'spring tide'?
Twice a lunar month, the moon, sun and Earth are in a straight line. At this point, the tide raising force is strongest, producing the highest monthly tidal range.
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What is the 'neap tide'?
Twice a lunar month, the moon and sun are at 90 degrees to each other in relation to Earth. This gives the lowest monthly tidal range.
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What is a storm surge?
a rising of the sea as a result of wind and atmospheric pressure changes associated with a storm.
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What is a sediment cell?
A distinct area of coastline separated by boundaries, e.g. headlands/deep water. They are, in theory, closed systems. There are 11 in England & Wales.
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What are characteristics of low energy coastlines?
Wave heights are lower, waves spread outward and energy dissipates, leading to the deposition of transported material. They can be estuaries, inlets and sheltered bays.
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What are some landforms produced by coastal deposition?
Beaches, cusps, bars and spits, sand dunes, salt marshes, mudflats.
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What is hydraulic action?
A breaking wave traps air as it hits a cliff. The water compresses into a gap in a rock face, creating enormous pressure. When the water pulls back, the pressure is released. The cracks eventually widen and the cliff's structure is damaged.
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What is abrasion/corrosion?
When material flung at a cliff by waves wears down the rock face.
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What is attrition?
Abrasive rocks worn by contact with each other into smaller, more rounded pieces.
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What is solution?
A form of weathering. The dissolution of calcium based rock by chemicals in sea water, and salt crystals forming and putting stress on rocks.
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What is longshore drift?
Waves approach the beach at an angle, pushing material up and across the beach. Backwash drags it straight back down, creating a right angle.
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What is weathering?
Weathering is the decay and disintegration of rock
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What are forms of biological weathering?
Marine organisms (eg piddock) drilling into rock. Some types of algae secretes chemicals that aid the process of solution.
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What are some more forms of biological weathering?
growing plant roots widen cracks as does the leverage created by bushes and trees swaying in strong winds. Burrowing animals and nesting birds excavate material in partially weathered and eroded cliffs.
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What is physical weathering?
Mechanical or physical weathering is the fracture and breakdown of rocks into fragments.
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What are some examples of physical weathering?
Freeze-thaw occurs when water gets into cracks in rocks and freezes. This then expands by around 10%. The repeated freeze thaw action puts pressure on the rocks until they eventually crack and break the rock.
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What are some more examples of physical weathering?
Salt crystallisation is when salt crystals are deposited in cracks and over time the salt accumulates and applies pressure to the crack.
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What are even more examples of physical weathering?
Wetting and drying is common along coastlines. Clay rich rocks are prone to expand when they are wet and contract when they dry. This results in cracks which are vulnerable to both freeze-thaw and salt crystallisation.
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What are some examples of chemical weathering?
A weak chemical reaction between water and rock. Rainwater mixed with carbon dioxide in the atmosphere forms Carbonic acid. This then reacts with calcium carbonate in limestone to form calcium bicarbonate.
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Chemical weathering continued.
Bicarbonate is soluble in water and the limestone gets weathered when carbonation occurs.
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What is mass movement?
Mass movement is the movement of material downslope as the result of gravity. This can be a slow process in the case of soil creep or fast in the case of rockfalls. Water commonly acts as a lubricant in mass movement.
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What are mudflows?
A mudflow is an earthflow consisting of material that is wet enough to flow rapidly and that contains at least 50 percent sand, silt, and clay-sized particles.
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What is slumping?
Marine processes erode and undermine the base of the cliff. Rainwater infiltrates the cliff through unconsolidated, porous material. This then creates a slip plane. The weight of the saturated clay causes the material to slump along the slip plane.
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Slumping continued.
The face of the cliff moves downwards, creating a concave slide plane, with a rotational movement.
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What is concordant geology?
Rocks roughly parallel to the coastline.
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What is discordant geology?
Rocks roughly perpendicular to the coastline.
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What are the main aims of coastal management?
To provide defence against flooding and to provide protection against coastal erosion. Other aims are to stabilise beaches affected by longshore drift, to stabilise sand dune areas and to protect salt marshes.
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What is hard engineering?
Hard engineering options tend to be expensive, short-term options. They may also have a high impact on the landscape or environment and be unsustainable. They have specific purposes, e.g. protecting a coastal town.
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What are some examples of hard engineering?
Sea walls, rock armour, gabians, cliff fixing, offshore reefs, barrages.
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What is soft engineering?
Often less expensive than hard engineering options. They are usually more long-term and sustainable, with less impact on the environment.
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What are some examples of soft engineering?
Beach nourishment, dune regeneration, managed retreat.
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What are some examples of soft engineering?
Beach nourishment, dune regeneration, managed retreat.
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Other cards in this set

Card 2


What is the foreshore?


The area between the high and low water marks. (The most important area for marine processes in non-storms).

Card 3


What is the inshore?


Preview of the front of card 3

Card 4


What is 'offshore'?


Preview of the front of card 4

Card 5


What is fetch?


Preview of the front of card 5
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