Coasts, Weathering and Erosion, Coastal Land forms of erosion, Transportation and Land forms of deposition.

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  • Created by: Tharv
  • Created on: 11-11-18 15:31

Weathering

-Breaks rocks down into one place.

-Mechanical

-Chemical

-Biological

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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.

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Chemical Weathering

Carbonic Acid > rock containing calcium carbonate (limestone & chalk) 

Carbonic Acid > Dissolves these these rocks.

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Biological Weather

Plants grow/break through a rock, splitting it in half.

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Erosion

Washes the material away.

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Attrition

Rocks hit against eachother > Smaller pieces

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Abrasion

Rocks scrape against eachother, into smaller faces.

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Solution

Weak Carbonic Acid in sea water dissolves rock e.g chalk & limestone.

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Hydraulic Power

Waves crash into rocks, compress air into cracks.

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Destructive Waves

-Erodes

-High Freq. (10-14 waves pm)

- High

-Steep

Backwash= more powerful than swash- material is removed from coast.

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Constructive Waves

- Deposit Material

- Low

-Long

-Low frequency (7-11 wpm)

-Backwash= Less powerful- Material is deposited 

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Land forms of erosion.

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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

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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.

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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.

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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. 

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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.

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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.

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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.

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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.

 

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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.

 

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Coastal Management Strategies~ Sea wall

-Hard engineering

- Usually thick concrete

- Deflects waves back into sea

- Prevents erosion- coast

- Very Expensive

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Coastal Management Strategies~ Rock Armour

Boulders are piled up parellel on coast

- Cheap defence.

- Moves around- strong waves.

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Coastal Management Strategies~ Beach Nourishment

- Soft Engineering

-  Sand and shingle from elsewhere is added to the beach from elsewhere.

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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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