Coastal Erosion - Landforms Flashcards
What factors affect the rate of erosion?
Rock Type – A more resistant rock, such as granite, will be eroded slowly, whilst a less resistant rock, such as clay or mud, can be eroded very quickly.
Jointing / Faulting – The more faults and joints a rock has the more susceptible it is to erosion, both from coastal and sub-aerial processes.
Coastal rock Arrangement – a coastline with rocks that run parallel to the coast is called a concordant coastline. One that has rocks running at right angles to the coast is called a discordant coastline.
Rock angle – The angle that the coastal rocks dip can also cause erosion to occur at different rates. Many rocks around the coasts of Britain are sedimentary, meaning they are layered.
How are cliffs shaped?
Cliffs are shaped through erosion and weathering. Soft rock erodes quickly and forms gentle sloping cliffs, whereas hard rock is more resistant and forms steep cliffs.
What is a wave-cut platform?
A wave-cut platform is a wide gently sloping surface found at the foot of a cliff.
How is a wave-cut platform formed?
The sea attacks the base of the cliff between the high and low water mark.
A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action – this is a dent in the cliff usually at the level of high tide.
As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
The backwash carries away the eroded material, leaving a wave-cut platform.
The process repeats. The cliff continues to retreat.
What is CASS and where is it seen?
Cave, Arch, Stack, and Stump is mainly seen on headlands.
How is CASS formed?
Waves start by attacking the main points of weakness in the rock: the joints and the faults.
A point of weakness is increased in size until it becomes a cave.
The waves continue to attack the cave, which finally results in an arch being formed through the headland.
The arch is attacked both by coastal erosion and sub-aerial erosion and finally the roof of the arch falls into the sea
This leaves behind a stack, which is then slowly eroded down to become a stump.
What is Durdledoor?
Durdledoor is an arch which has formed on a hard limestone headland. It is unusual as it has formed parallel to the coastline. Erosion by waves opened a crack in the headland, which then became a cave and eventually an arch. The arch is gradually being worn away by physical, chemical, and biological weathering.
What is Lulworth Cove?
Lulworth Cove is a cove formed when a gap was eroded in a band of limestone. Behind the limestone is layer of clay which is softer so more easily eroded. The limestone cliffs forming the back wall of the cove are vulnerable to mass movement and sometimes experience small slide and slumps.
What is Chesil Beach?
Chesil Beach is a tombolo (spit chich connects mainland to an island). It connects the Isle of Portland to the mainland. It has been created by longshore drift. Behind Chesil Beach is a lagoon called The Fleet Lagoon.
