Coasts Flashcards
LEARN UPLANDS AND LOWLANDS
LEARN UPLANDS AND LOWlANDS
what are the characteristics of a constructive wave?
- sheltered bays
- common in summer
- strong swash, weak backwash
- build up beaches
what are the characteristics of a destructive wave?
- exposed bays
- build up pebble beaches
- common in winter
- weak swash stronger backwash
how does mechanical weathering method of free-thaw weathering break down rock?
- bellow freezing
- water in rocks and cracks
- water freezes, pressure
- melts, release pressure
- repeated breaks rock
how does the chemical weathering method of carbonation weathering break down rock?
- rainwater- carbon dioxide
- which has weak carbonic acid
- reacts with calcium carbonate in rock
- i.e limstone dissolves
what is the definition of mass movements and when is it more likely to occur?
- shifting of rock and loose material down a slope
- full of water, heavier
what are the 3 main mass movements and what is the difference?
- sildes- shifts in straight line
- slumps- shifts with rotation
- rockfalls- material breaks up
what are the 3 processes of erosion?
- hydraulic power
- abrasion
- attrition
how does hydraulic power work?
- waves crash against rock
- compress air in cracks
- pressure on rock
- repeated compressing breaks rock
how does abrasion work?
-eroded particles I water scrap and scrap rock removing small pieces
how does attrition work?
- erodes particles smash into each other
- turn into small fragments
- edges round off
how does the transportation process of longshore drift work?
- waves follow prevailing wind
- hit coast at oblique angle
- swash carries material up beach
- backwash material back at RIGHT ANGLES
- zig zags along coast
what are the 4 processes of transportation? and what are they?
- traction- large particles, force of water
- saltation- pebble sized bounce along
- suspension- small particles carried in water
- solution- soluble material
why is sediment deposited in coastal areas?
- erosion elsewhere
- lots of transport into area
- sediment slowing down
- low energy waves
what are the landforms formed from erosion?
- wave-cut platforms
- headlands and bays
- caves, arch, stacks, stumps
‘waves erode cliffs to form was cut platforms’
how are wave cut platforms formed?
- most erosion at base of cliff
- forming wave cut notch
- rock above becomes unstable, falls
- material washed away
- repeated process
- wave cut plate form left behind as cliff retreats
how are headlands and bays formed?
- form different rock types, soft and hard rock
- soft rock erode quickly, bays
- hard rock slowly, jutting out, headlands, steep sides
‘headlands erode to form caves, arches and stacks’ how are cave, arches and stacks formed?
- wash crash enlarge cracks, hydraulic power, abrasion
- repeated erosion, caves
- repeated erosion, breaks through arch
- freeze thaw break roof, collapses
- stack formed
what are the land forms caused by deposition?
- beaches
- sand dunes
- spits and bars
how are beaches formed?
- constructive waves
- depositing sand and shingle
what are the characteristics of a sand beach?
- flat, wide
- small particles
- long gentle slope
what are the characteristics of a shingle beach?
- steep, narrow
- large shingle particles
- steep slope
how are spits formed?
- sharp bend in coastline
- longshore drift transports past bend, deposits in sea
- strong winds cure end. (recurved end)
- sheltered area behind protected
- forms out flat/ salt marsh
how are bars formed?
- spit joins two headlands
- cute headlands from sea
- lagoon formed
how are sand dunes formed?
- sand deposited by longshore drift moves up beach by wind
- obstacles (driftwood), sand deposited
- colonised by pants forcing more sand to settle
- forming small dunes.
- over time get larger and migrate, unto 10m
what examples of coastal landforms are found at Dorset coast?
- Durdle door- arch
- Lulworth Cove- bay
- Chesil Beach- bar
- Swanage bay- 2 bays
what are the 4 main hard engineering coastal defences?
- sea wall
- rock armour
- gabions
- groynes
what are the 4 main soft engineering coastal defences?
- beach nourishment
- beach reprofiling
- dune regeneration
what are the benefits and costs of a sea wall?
B- prevents flooding, prevents erosion
C- strong backwash, erode under wall, expensive
what are the benefits and costs of rock armour?
B- absorb wave energy, cheap
C- borders moved by strong waves, replacing
what are the benefits and costs of gabions?
B- absorb wave energy, easy to build, cheap
C- ugly, corrode over time
what are the benefits and costs of groynes?
B- wider beaches, slow waves, flooding protection, cheap
C- stave beaches further down
what are the benefits and costs of beach nourishment and reprofiling?
B- wider beach, slow waves, no flooding, erosion
C- repeated, expensive, kill habitats from where your’e taking it
what are the benefits and costs of dune regeneration?
B- barrier, wave energy absorbed, flooding, stabilisation is cheap
C- limited protection to small area, nourishment is expensive
what is managed retreat?
removing coastal defences, allow sea to flood land
what are the benefits and costs of managed retreat?
B- cheap, easy, no maintenance, new habitats
C- conflicts, flooding farmland
what is an example of coastal management In the UK?
Holderness Coast
North East England
what are the reasons for management at Holderness Coast?
- prevailing winds moving sediments south
- 10m per year lost
- farms, homes and business threatened
- population over 14000 in local area
- local gas terminal supplies UK 25%
what is the management’s strategy at Holderness Coast?
- at Mappleton
- 2 million
- 61000 tonnes of rock
- rock armour at base of cliff
- two rock groynes to trap sand and creat beach
‘The defects saves Mappleton… but still used conflict’ what are the resulting conflicts and effects?
- loss of land to sut, Great Cowden’s farm
- loss of wildlife at Spurn Head
- maintaining defences will be expensive
