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Geography - Coastal Processes - Coggle Diagram
Geography - Coastal Processes
Mass Movement
shifting of rocks and loose material down a slope
gravity
causes coasts to retreat rapidly
more likely when material is full of water
lubricant
material feels heavier
Landslides
blocks of rock slide downhill along slide plane
Mudflow
saturated soil and weak rock flows down a slope
Rockfalls
fragments of rock break away from cliff face
Rotational Slip
slump of saturated soil and weak rock along curved surface
Waves
Destructive
high frequency
high and steep
backwash more powerful than swash
swash
material is removed
Constructive
low frequency
low and long
swash more powerful than backwash
material deposited (builds beach)
Formed
wind blows over surface of the sea
friction occurs
pushed in direction of wind
waves
stronger wind
greater friction
bigger wave
longer fetch
greater potential wave energy
transfer of energy through water
Why do they break?
energy moves in circular motion
shallow, coastal waters
base of wave makes frictional contact with seabed
slows base of wave
reduce distance between waves
increase wave height
top of wave moves faster than base
Erosion
Hydraulic power
waves crash against rock
compress air in cracks
pressure on rock
reapeated compression widens cracks
bit of rock break off
Abrasion
eroded particles in water scrape and rub against rock
removing small pieces
sandpaper effect
smooth
Attrition
eroded particles collide
smaller and more rounded
Longshore Drift
transport of sediment along coast caused by waves approaching beach at angle
prevailing wind = direction of waves
swash carries material up beach
backwash carries material down at right angles
zigzags
Transportation
Traction
large pebbles pushed along seabed
Suspension
particles carried along water
Saltation
pebble-sized particles bounced along seabed
Solution
dissolved chemicals
e.g. limestone
Coastal Deposition
waves lose energy and slow down
coasts build up when amount of deposition is greater than erosion
amount of material deposited increases when
erosion elsewhere
more material available
lots of material transported into area
Wave Refraction
waves change direction as they approach the coastline
wave energy become concentrated on headlands and spread out in bays
more erosion on headlands
more deposition in bays
Weathering
Mechanical
breakdown of rock without changing chemical composition
freeze-thaw weathering
temperature alternates above and below 0°C
water enters rocks with cracks
when water freezes and expands
pressure on rocks
when water thaws it contracts
releases pressure
repeated process widens cracks
rock breaks up
Chemical
breakdown of rock by changing chemical composition
Carbonation
warm and wet conditions
rainwater has carbon dioxide
weak carbonic acid
reacts with alkaline rock e.g. chalk
rocks dissolved by rainwater
Biological
action of flora and fauna
plant roots grow in cracks
animals burrow into weak rocks and minerals
rabbits