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Coastal Landscapes in the UK 1 (Erosion (Hydralic action (This is the…
Coastal Landscapes in the UK 1
Process of mass movement and slumping
Mass movement
: the downhill movement of sediment that moves because of gravity. There are four different types of mass movement:
Rock fall
Landslide
Mudflow
Rotational slip
Slumping
: with rotational slumping, heavy rain is absorbed by unconsolidated material making up the cliff. The cliff face becomes heavier and eventually it separates from the material behind at a rain-lubricated slip plane.
Coast
The Coast in a part of the land that ajoins or is near the sea
Pembrokeshire Coastline
Erosion
Hydralic action
This is the sheer power of the waves as they smash against the cliff. Air becomes trapped in the cracks in the rock and causes the rock to break apart.
Abrasion
This is when pebbles grind along a rock platform, much like sandpaper. Over time the rock becomes smooth.
Attrition
This is when rocks that the sea is carrying knock against each other. They break apart to become smaller and more rounded.
Solution
This is when sea water dissolves certain types of rocks. In the UK, chalk and limestone cliffs are prone to this type of erosion.
Weathering
Mechanical weathering is the breakdown of rock without changing its chemical composition.
There's one main type of mechanical weathering that affects coasts - free-thaw weathering.
Chemical weathering is the breakdown of rock by changing its chemical composition.
There is one main type of chemical weathering that affects coast - carbonation weathering.
Erosional Landforms
Caves, arches, stacks and stumps
Cracks are widened in the headland through the erosional processes of hydraulic action and abrasion.
As the waves continue to grind away at the crack, it begins to open up to form a cave.
The cave becomes larger and eventually breaks through the headland to form an arch.
The base of the arch continually becomes wider through further erosion, until its roof becomes too heavy and collapses into the sea. This leaves a stack (an isolated column of rock).
The stack is undercut at the base until it collapses to form a stump.
Headlands and bays
Cliffs and wave-cut platforms
Mass Movement
Mass movement is the shifting of rocks and loose material down a slope, e.g. cliffs. It happends when the force of gravity acting on a slope is greater than the force supporting it.
This causes coasts to retreat rapidly.
They are more likely ro happend when the material is full of water - it acts as a lubricant, and makes the material heavier.
Erosion and deposition
Deposition
: When the sea loses energy, it drops the material it has been carrying. This can occur on coastlines that have constructive waves.
Erosion
: the wearing away of rock along the coastline. Destructive waves are responsible for erosion on the coastline.
These can effect people living on the coast. for example people that have houses on cliffs will have to move as the cliff will slowly retreat. However nobody will want to buy the house as it will soon be destroyed.
Waves
Constructive waves
Their swash is stronger than their backwash
small and low
They have a low frequency
Destructive waves
They have a high frequency
Steep and high
Their backwash is more powerfull than there swash.
