are four main processes which cause coastal erosion. These are
corrasion/abrasion, hydraulic action, attrition and corrosion/solution.
is when waves pick up beach material (e.g. pebbles) and hurl
them at the base of a cliff.
waves hit the base of a cliff air is compressed into cracks.
when the wave retreats the air rushes out of the gap. Often
this causes cliff matrial to break away. This process is known
as hydraulic action.
is when waves cause rocks and pebbles to bump into each other
and break up.
is when certain types of cliff erode as a result of weak acids
in the sea.
is greatest when waves break at the foot of a cliff. This causes
erosion at the base of the cliff. This creates a wave-cut notch
in the base of the cliff. As the notch increases in size the
weight of the cliffs above become too much and the cliff collapses.
This material will provide temporary protection for the cliff
behind. However, once it has been removed by the sea this process
will occur again. Where cliffs are made of more resistant material,
wave cut platforms will be created.
Erosion of a headland
headland is an area of hard rock which sticks out into the sea.
Headlands form in areas of alternating hard and soft rock. Where
the soft rock erodes bays are formed either side of the headland.
As the headland becomes more exposed to the wind and waves the
rate of its erosion increases. When headlands erode they create
distinct features such as caves, arches, stacks and stumps.
The diagram below shows the sequence in the erosion of a headland.
a weakness in the headland.
A cave is
the cave erodes through the headland to form an arch.
The roof of
the arch collapses leaving a column of rock called a
collapses leaving a stump.