2.3 Coasts Flashcards
Corrasion
Large waves through material at the cliff
Corrosion
Acids and salts slowly dissolve a cliff.
Attrition
Waves cause stones to bounce on each other and break down.
Hydraulic action
Force of waves compresses air in cliffs, causing the rock to weaken.
Explain how longshore drift transports material along the coast.
Waves approach the coast in the direction of the prevailing wind.
Swash moves up the beach at an angle.
Backwash drains straight back down the beach (due to gravity.
Material moves in a zig-zag motion.
Swash
When a wave breaks and washes up the beach.
Backwash
When water drains back to the sea
Characteristics of a constructive wave
Strong swash
Weak backwash
Deposits material
Create a gentle beach gradient.
Characteristics of a destructive wave
Strong backwash
Weak swash
Erodes material
Create a steep beach gradient
Explain how cliffs are eroded and wave-cut platforms created
Erosion is concentrated at the foot of the cliff
A wave-cut platform is created
Cliff is undercut and collapses
This causes the cliff to retreat
How are caves, arches, stack and stumps created?
A crack/weaker rock in the headland is eroded to form a cave.
More erosion produces an arch through the headland.
Eventually the roof is weak and collapses forming a stack.
Further erosion causes the stack to ‘sink’ and forms a stump.
Why are beaches formed in bays?
In bays, waves diverge outwards.
This creates a low energy environment and therefore material is deposited to form beaches.
Why are bays and headlands formed?
Bays are parts of the coast with softer rock that has been eroded faster/more easily.
Headlands are parts of the coast with harder rock that erodes really slowly.
How are spits formed?
The coastline changes direction
Longshore drift keeps carrying material in same direction.
When the material reaches more open sea, it deposits material to form a spit.
End of spit curves due to a change in wind.
How are sand dunes formed?
Onshore winds pick up sand from the beach and carry it landward.
This winds then find an obstacle and deposit the sand.
Eventually a dune is formed.
Plants grow, stabilising the dune and trapping more sand.