coasts lesson 3 (erosion)
DESCRIPTION
Lesson 3 worksheetTRANSCRIPT
CoastsCoastsAim: To be able to draw and describe Aim: To be able to draw and describe some landforms of coastal erosion.some landforms of coastal erosion.
Key WordsKey Words
•Cave
•Arch
•Stack
•Wave Cut Platform
What factors affect rate of
coastal erosion?
Beaches
Absorb wave energy which slows down erosion by protecting cliffs
Rock structure
Cliffs with weaknesses (joints) and cracks are more easily eroded
Rock type
Resistant rocks eg. granite erode very slowly. Less resistant eg. clay erode quickly
Wave energy
Erosion greatest when waves and big and frequent
Weathering
Sub-aerial attack on cliffs speed up erosion (wind & rain)
and don’t forget …… PEOPLE
Headlands and BaysHeadlands and BaysThey form along coasts that have alternating bands of hard and soft rock
Lulworth CoveLulworth Cove
Click on picture above for a Click on picture above for a short video on how bays are short video on how bays are formed 2.03formed 2.03
Cliff ErosionCliff Erosion
Click diagram above for a short video about cliff collapse in Beachy Head 1.45Click diagram above for a short video about cliff collapse in Beachy Head 1.45
What happens at the cliff face?
•Is affected by sub-aerial weathering (impact of wind, rain, frost, temperature changes)
•This may lead to mass movement ~ face of cliff slips/slides downwards
•This often happens after prolonged or heavy rain – reduces frictional surfaces and makes rocks unstable
Wave Cut PlatformsWave Cut Platforms
The sea cliff is the most widespread landform of coastal erosion.
Caves, Arches and StacksCaves, Arches and Stacks
ArchArch
StacksStacks
Caves, Arches and StacksCaves, Arches and Stacks
Waves erode weaknessesin the rock.Cave eroded
into cliff at line of weakness
Size of caveis increased by
erosion untilheadland
is opened outat both sides
Wave erosioncauses roof of
cave to collapse leaving
the stack
Transport and DepositionTransport and DepositionLongshore DriftLongshore Drift
Click on diagram to Click on diagram to start short video on start short video on longshore drift 2.06longshore drift 2.06
Longshore Drift in actionLongshore Drift in action