Coasts, Weathering and Erosion, Coastal Land forms of erosion, Transportation and Land forms of deposition.
- Created by: Tharv
- Created on: 11-11-18 15:31
Weathering
-Breaks rocks down into one place.
-Mechanical
-Chemical
-Biological
Freeze Thaw Weathering
1. Cracks fill up with water.
2. Water freezes, expands 9%
3. Pulls rock apart, Larger Crack
Happens with alternating temperatues (just above or below 0'c, when the water thaws, it contracts to release pressure.
Chemical Weathering
Carbonic Acid > rock containing calcium carbonate (limestone & chalk)
Carbonic Acid > Dissolves these these rocks.
Biological Weather
Plants grow/break through a rock, splitting it in half.
Erosion
Washes the material away.
Attrition
Rocks hit against eachother > Smaller pieces
Abrasion
Rocks scrape against eachother, into smaller faces.
Solution
Weak Carbonic Acid in sea water dissolves rock e.g chalk & limestone.
Hydraulic Power
Waves crash into rocks, compress air into cracks.
Destructive Waves
-Erodes
-High Freq. (10-14 waves pm)
- High
-Steep
Backwash= more powerful than swash- material is removed from coast.
Constructive Waves
- Deposit Material
- Low
-Long
-Low frequency (7-11 wpm)
-Backwash= Less powerful- Material is deposited
Land forms of erosion.
Headlands and Bays
-Layer of hard and soft rock
-Softer rock breaks > headland bay
- Tougher, more resistant rock (limestone or sandstone) eroded much slower > stick out into sea forming headland
Caves, Arches and Stacks
-A joint or fault in resistant rock
-Abrasion & hydraghlic widens joint
-Waves make cave larger until it cuts through headland to make arch.
-Arch is eroded and roof becomes too heavy and collapes.
-Leaves a tall stack
-Stack is eroded, collapses > Stump.
Mass Movements
-Material shifting down slope as one.
-Rocks and loose material
-Slope (cliff for e.g)
-Happens because of gravity
-Coast retreats more rapidly.
- Most likely to happen after heavy rain.
- Water acts as a lubricant.
Holderness.
-Fastest eroding coastline in Europe.
-Approx. 1.8m of land lost/year.
-Some places 10m
Eroding because:
> Boulder Clay (soft) slumps when wet- eroded easily
> Powerful waves > Arctic > Powerful, batter sea coast.
Sand Beaches (Land forms of deposition)
-Flat and Wide
-Sand particles are small.
-Weak back wash can move then down coast, creating a long gentle slope.
Shingle Beaches (Land forms of deposition)
-Steep and Narrow
-Shingle particles are large.
-Backwash can't move them back down beach.
-Shingle builds > Steep slope.
Spits
- Form at sharp ends in coatline (e.g River Mouth)
-Longshore drift transports sand and shingle past the bend and deposits it in the sea.
Transportation
- Prevailing winds > Sea > Zig zag direction
- Backwash and swash move material along beach.
- LONGSHORE DRIFT.
Traction: large rocks rolling
Saltation: Pebble sized particles > bounced along sea bed > force of the water.
Solution: Soluable materials are dissolved in sea > Carried along.
Suspension: Small material e.g Clay > carried along in sea.
Transportation
- Prevailing winds > Sea > Zig zag direction
- Backwash and swash move material along beach.
- LONGSHORE DRIFT.
Traction: large rocks rolling
Saltation: Pebble sized particles > bounced along sea bed > force of the water.
Solution: Soluable materials are dissolved in sea > Carried along.
Suspension: Small material e.g Clay > carried along in sea.
Coastal Management Strategies~ Sea wall
-Hard engineering
- Usually thick concrete
- Deflects waves back into sea
- Prevents erosion- coast
- Very Expensive
Coastal Management Strategies~ Rock Armour
Boulders are piled up parellel on coast
- Cheap defence.
- Moves around- strong waves.
Coastal Management Strategies~ Beach Nourishment
- Soft Engineering
- Sand and shingle from elsewhere is added to the beach from elsewhere.
Coastal Management~ Holderness- Mappleton
- Rock Groynes built- 1991
- Ptotect village- erosion and flooding.
- 3ft cliff lost/year
-Hardly any beach- waves directly hit.
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