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69 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the backshore?
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The area between the HWM and the landward limit of marine activity (changes take place during storm activity)
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What is the foreshore?
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The area lying between the HWM and the LWM (most important zone for marine processes)
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What is the inshore?
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The area between the LWM and the point where the waves cease to have any impact on the land beneath them
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What is the offshore?
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The area beyond where waves cease to impact upon the sea bed and which activity is limited to deposition of sediments
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What is an open system?
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A coastline is regarded as an open system because inputs are received, processes cause changes within the system and outputs are transferred out
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What are the eight main factors that affect the coast?
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Biotic, climatic, marine, human, tectonic, sedimentation, atmospheric and geology
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What is a coast?
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The narrow zone where the sea meets and interacts with the land
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What are tides?
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Tides are the result of two forces pulling the water at the Earth's surface
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What are the two forces pulling the water at the Earth's surface?
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The sun (solar tide) and the moon (lunar tide)
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Why does the moon have a greater gravitational pull than the sun?
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Due to it's proximity (the moon is closer to the Earth than the sun)
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What is an oscillation wave?
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An imaginary particle would move in a clockwise direction between wave crest, trough, then back to the crest of the wave, but would not move forward in the ocean
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What causes a spring tide?
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When the sun and moon are aligned (full moon and new moon) there is a very high tidal range and this causes spring tides
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What is the strata?
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The layer of rock
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What is the bedding plain?
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The separation line between two stratas
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What are the joints?
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Weak, vertical cracks in different stratas
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What type of waves break at the foot of the cliff in the formation of WCP/N?
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Steep and high waves
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What is the simple formation of a wave cut notch?
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High and steep waves break at the foot of the cliff and concentrate erosion to a small area of rock face. The concentrated erosion leads to the cliff becoming undercut forming a wave cut notch
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After a wave cut notch has been formed, how does it make the platform?
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The waves begin to break further out at sea and they travel across the platform before meeting the cliff line. The waves are less forceful and there is a greater dissipation of wave energy, so that erosion rate reduces
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What is an example of a concordant coastline?
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Durdle Door
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What is the proper name for clay?
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Greensand and Wealdon clay
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What is the proper name for limestone?
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Portland and Purbeck limestone
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What are the two fast eroding sediments?
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Sand and clay
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When a wave orthogonal converges...
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Energy is high; fast erosion - forms headlands
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Cliff profiles vary due to...
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Rock type and resistance, weaknesses, geological structures and active/inactive states
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What are the three cliff profile categories?
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Vertical, variable steepness and low-angled
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What is cliff retreat?
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The process in which a cliff is eroded to create a wave-cut notch and platform
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When a wave orthogonal diverges...
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Energy is less; slower erosion; forms coves/bays
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An example of a wave cut platform?
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Flamborough Head, Yorkshire (well developed WCP made of chalk)
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What is a spit?
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A long, narrow piece of land, where one end is joined to the mainland and the other end projects out into the sea or across an estuary
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How is a spit formed?
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South-west prevailing winds and maximum fetch, so material will be carried from west to east by LSD across the coastline; until the coastline chanted to a north-east orientation. There will therefore be a build up of material (sand and shingle) in the lee of the headland. The spit will then begin to project eastwards and storms will build up the sediment, giving it a greater degree of permanence
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Why do some spits have a recurred end?
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Some spits are recurved due to wave refraction carrying material around to more sheltered water
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The formation of a sand dune behind a spit...
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Sand dunes form when dried out sand is blown to the back of a spit where it then accumulates. Stability is achieved if vegetation begins to colonise (such as marram grass) to hold the dunes together
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What is a salt marsh?
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An area of coastal grassland that is regularly flooded by sea water
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How do salt marshes form?
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They form when low-energy, gentle waves enter the sheltered area behind the spit and deposit finer material like silt and mud. It builds up to form a feature which is then colonised by vegetation
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Why is coastal management so important?
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To provide defence against flooding and to provide protection against coastal erosion
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H
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What is hard engineering?
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Building some type of sea defence ugh specific purpose
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What is soft engineering?
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Natural systems for cliff defence
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Examples of hard engineering?
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Sea wall, groynes, rock armour, gabions, revetments, cliff fixing, offshore reefs, barrages
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Examples of hard engineering?
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Sea wall, groynes, rock armour, gabions, revetments, cliff fixing, offshore reefs, barrages
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Examples of soft engineering?
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Beach nourishment, dune regeneration, managed retreat or do nothing
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Examples of soft engineering?
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Beach nourishment, dune regeneration, managed retreat or do nothing
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What is a recurved sea wall?
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A wall made of concrete that aims to absorb wave energy. The recurved structure throws waves backwards
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What is a recurved sea wall?
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A wall made of concrete that aims to absorb wave energy. The recurved structure throws waves backwards
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What is rip-rap (rock armour)?
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Consists of large boulders dumped in front of a cliff/sea wall to take wave force
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What is rip-rap (rock armour)?
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Consists of large boulders dumped in front of a cliff/sea wall to take wave force
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What are revetments?
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Wooden or concrete structures with open structure planks to absorb the full force of wave energy
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What are revetments?
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Wooden or concrete structures with open structure planks to absorb the full force of wave energy
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What is a groyne?
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A wall built at a right angle to the waves to control LSD but also break the waves as they hit the coast
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What is a groyne?
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A wall built at a right angle to the waves to control LSD but also break the waves as they hit the coast
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What is a disadvantage of a groyne?
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It can lead to other areas of coastline not having much sediment and therefore being open to more rapid erosion
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What is a disadvantage of a groyne?
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It can lead to other areas of coastline not having much sediment and therefore being open to more rapid erosion
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What is a gabion?
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Operates the same as rip-rap but is instead concealed in a steel cage
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Barrages...
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Acts as a dam and prevents the incursion (attack) of sea water
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Barrages...
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Acts as a dam and prevents the incursion (attack) of sea water
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What are the cons of barrages?
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They are expensive and can create yeah water lakes where mudflat areas should be and breeding grounds for birds
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An example of a barrage?
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Cardiff Bay barrage
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Hard engineering disadvantages...
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Structures can be expensive to build and maintain, defence in one place can have consequences on another part of the coastline, defence structures may not keep pace with rising sea levels, they can be seen as eyesores as they ruin the land scape
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Failed sea defences at the Isle of Wight...
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Monk's Bay, Castle Cove, Castlehaven and East of Freshwater
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Four coastal defences?
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Hold the line, do nothing but monitor, retreat the line and advance the line
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What does it mean to hold the line?
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To attain existing coastline by maintaining current sea defences and building replacements if need be
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What does it mean to do nothing but monitor?
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Some places aren't viable to undertake defence works and therefore monitoring takes place only
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What does it mean to retreat the line?
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Actively manage the rate and process of cliff retreat and act accordingly
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What does it mean to advance the line?
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Build new defences seaward of the existing line
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What are offshore reefs?
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A reef that forces the wave to break offshore which reduces the impact on the base of cliffs
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What is cliff fixing?
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Often done by driving iron bars into the cliff face, both to stabilise and absorb wave power
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What is beach nourishment?
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The attempt to replace material that has been lost from LSD
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What is dune regeneration?
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Fragile sand dune environment is easily disrupted by human activity (agriculture and tourism remove vegetation and damage occurs). Replanting vulnerable plant areas, choosing selective grazing and providing boardwalks for tourists will prevent dune damage
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What is managed retreat?
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Abandon current line of defence and develop exposed land (salt marshes) to slow force of waves
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Examples of soft engineering?
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Pevensey Bay, East Sussex - beach reprofiling, beach replenishment, beach monitoring
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