2.8 - Does Mass Movement Change Coastlines Flashcards
Highcliffe/Baron
Christchurch Bay
Concordant Coastline
Stresses
Angle of slope
Weight of buildings
Marine erosion
Rain from clouds
Earthquakes
Vibrations e.g. cars
Strengths
Landward dip
Vegetation
Lubricated layers –> water can’t percolate
Porosity of soil
Faults/Joints
Small cracks get into the rock
Water gets into the crack
Joints expand and contract
Stresses increase on cliff
Rock begins to slide downwards
Faults/Joints
Small creates get into the rock
Water gets into the crack
Joints expand and contract
Stresses increase on cliff
Rock begins to slide downwards
Blockfall
Starts by weathering/marine erosion. Marine erosion then undercuts into a wave cut notch causing detachment of single sections of the cliff.
Rotational Slumping
Rock failure and movement along a curved rock plane, this usually moves as a single slump without decomposing material, it happens when rock is saturated, uncosnoldiated and weak.
Topple
Where rock strata have a very steep seaward dip, undercutting by erosion will quickly lead to instability and blocks of material sliding down the dipslope towards the sea.
Flow
Flows are common in weak rocks, these materials become saturated, lose cohesion and flow downslope
Mass Movement Can Be Managed
To reduced water percolation, slopes can be covered by concrete and walls can be built to increase stabilisation.
Rock armour can prevent topple
Pipes can help drain water and prevent saturation.
Vegetation can be implanted to prevent saturation and stabilise the cliff.
Mass Movement Can’t Be Managed
The angle and direction of the dip can’t be altered, seaward dips are more damaging.
It’s expensive to prevent erosion in all areas and prevent stress from being induced on land meaning it can’t be done everywhere.
