Coastal Landforms
- Cliffs and wave cut platforms
- Beaches
- Caves, arches, stacks and stumps
- Headlands and bays
- Spits
- Summary
Cliffs and wave cut platforms
Sea cliffs are the most common landform of coastal erosion.
Cliffs begin to form when destructive waves attack the base of
the rock face between the high and low water marks.
Processes such as hydraulic action and corrasion undercut
the base of the cliff to form a WAVE CUT NOTCH.
The rock above hangs over the notch and with continued
wave attack the notch begins to widen, until the overhangs
weight becomes so great it collapses.
The waves set about gradually removing all of the waste rock
and then begin to attack the new cliff face again. The process
continues again and again until eventually a WAVE CUT
PLATFORM remains.
A WAVE CUT PLATFORM is a gently sloping rocky area
between the high and low water marks.
Beaches
The beach is a gently sloping area of land between the high and low water
marks.
Beaches differ from place to place as result of the size of the fetch, human
interference and material type.
The most common beach materials are sand, shingle and pebbles. Sandy
beaches are usually gently sloping but coarser materials such as large
shingle allow steeper gradients to develop. Some of the material may be
thrown up into steep ridges by storm waves.
The materials from which a beach are formed are carried by longshore drift
along the coast.
Caves, arches, stacks and stumps
Waves often tend to find any weakness or crack in a
rock and widen it by the process of hydraulic action.
This often results in the formation of caves on a
headland.
Once the cave has formed, the waves are able to enter
and continue eroding back into the headland until they
eventually break through to form an arch (for example
Durdle Door in Dorset).
In time, the base of the arch is attacked by the waves
and this puts increasing pressure on the roof of the
arch. If there is a weakness in the roof of the arch, it
will collapse leaving a tall, isolated stack (for example
Old Harry, Dorset coastline)
The stack is the attacked at the base by the force of
the waves and will eventually collapse to form a stump
(for example Old Harry’s wife, Dorset coastline)
Headlands and bays
Headlands and bays forms where a coastline if made up of alternating resistant
(harder) and less resistant (softer) rock.
At some points along the coastline the rock will be eroded as it is less resistant
and in other areas the rock will remain as it is more resistant.
This results in certain areas of the coastline sticking out to sea to form
HEADLANDS ( for example Flamborough Head, Yorkshire coastline) and other
areas are eroded away to form BAYS (for example Lulworth Cove, Dorset
Coastline)
Spits
A spit is a long, narrow ridge of sand or shingle.
One end of the spit is attached to the land and the other end
extends out into the sea.
The process of longshore drift carries material along the
beach. When the coastline changes direction or where there
is a river estuary, the longshore drift continues to move
material in the same direction. In this way, a ridge of
deposited material gradually builds up in the deeper water. If
the winds sometimes blow from a different direction, this can
cause material to be moved in a different direction and the
spit develops a ‘hooked’ or curved end.
Behind the spit, in the calm water, mud is deposited and salt
marsh will develop. On the spit itself, sand can be piled up by
the wind to form sand dunes.
An example of a spit in the UK is Spurn Point which can be
found along the Yorkshire Coastline
SUMMARY
-A wave cut notch forms when destructive waves undercut a cliff face
- The collapse of the overhang above a wave cut notch and the retreat of the
cliff eventually results in the formation of a wide, rocky wave cut platform
- The beach is a gently sloping area of land between the high and low water
marks and consists of sand, shingle and larger pebbles.
- Caves, arches, stacks and stumps are formed when destructive waves erode
a headland
- Headlands and bays form in areas of alternating resistant and less resistant
rock
-A spit is a long, narrow ridge of sand and shingle extending out into the sea or
across a river estuary.