Coastal erosion

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Coastal erosion
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Coastal erosion

• How does a headland erode?

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Coastal erosion
Headlands form along coastlines in which bands of
soft and hard rock outcrop at right angles to the
coastline. Less resistant rock (e.g. boulder
clay) erodes more rapidly than less resistant
rock (e.g. chalk).
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Coastal erosion
The following slides show the sequence that takes
place when a headland is attacked by wave action.
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Wave-cut notch Waves erode the base of the cliff
by hydraulic action and abrasion. In the case of
this chalk cliff at Étretat in Normandy, the
chalk rock is also dissolved by corrosion.
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Cave Lines or zones of weakness along the cliff
erode more quickly than the rest of the headland
and form caves. Such wearing away at different
rates is known as differential erosion.
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Arch Over a long period of time, the cave erodes
deeper into the headland. Another cave forms on
the other side of the headland along the same
line of weakness. Gravity causes loose rock to
fall from the roof of the cave. The two caves
finally join to form an arch.
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Stack Agents of erosion continue to work on the
rock forming the arch. Eventually, the roof
collapses due to gravity, forming a stack.
Weathering of the rock also takes place. This
stack erodes and weathers further to form a
low-lying stump before eventually eroding to sea
level.
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Wave-cut platform As the cliff slowly retreats, a
gently sloping area of rock is left behind at sea
level. This is a wave-cut platform.