Coasts Flashcards

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1
Q

When backwash > swash = _____

A

Destructive wave

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2
Q

When swash > backwash = _________

A

Constructive wave

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3
Q

What is a destructive wave

A

Formed by strong winds, high energy levels. Erodes beach material

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4
Q

What is a constructive wave

A

Calmer weather, less powerful, don’t break as violently.

More material carried up beach than down

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5
Q

What causes a tidal bulge

A

When the sun and moons gravity pull on earths ocean waters

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6
Q

Abrasion

A

Waves pick up material and hurl them at base of cliff

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7
Q

Hydraulic action

A

Air trapped, compresses, pressure of water weakens rock and breaks

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8
Q

Solution/ corrosion

A

Acids in sea dissolve rocks e.g. - chalk and limestone

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9
Q

Attrition

A

Waves smash rocks and pebbles on shore into each other - they break and gradually get smaller

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10
Q

Fetch

A

Length of water waves travel

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11
Q

What are sub aerial processes

A

Land based which alter shape of coastline. Combo of weathering and mass movement

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12
Q

Different types of weathering

A

Freeze thaw action
Exfoliation
Biological weathering
Chemical weathering

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13
Q

Exfoliation.

A

Respected action of heating and cooling rocks causing them to shed off layers

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14
Q

Biological weathering

A

Plant seeds get into cracks and begin growing, put pressure on rocks causing them to fracture

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15
Q

Chemical weathering

A

Hydrolysis - splitting of materials due to reactivity with water
Oxidation - Rusting

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16
Q

What are the different types of mass movement (5)

A
Rockfalls 
Soil creep 
Landslides
Rotational slumping 
Mudflow
17
Q

Rockfalls

A

FTW breaks rock into smaller pieces and this can free fall

18
Q

Soil creep

A

Damp soil moves slowly downhill due to increase in mass OR as a result of freezing and thawing

19
Q

Landslides

A

After being soaked with water, cliffs made from soft rock will start to slip due to rock being lubricated

20
Q

Rotational slumping

A

Heavy rainfall makes rock heavier due to absorbing water and lubrication

21
Q

Mudflow

A

Steep slopes, saturated soil and little vegetation - rapid movement of mud downhill

22
Q

Formation of a cave, arch, stack, needle and stump

A

Cave:
Weaknesses in the rock gets eroded by hydraulic action and abrasion
Arch:
More hydraulic action and abrasion also sub serial
Stack:
Arch collapses bc too heavy - detached stack
Needle:
Thinner stack
Stump:
Eroded needle

23
Q

Formation of wave cut platform

A

Starts as wave cut notch, waves erode notch by high water mark erosion (hydraulic action + abrasion) + sub aerial (FTW) + mass movement (rockfalls)

*Explain how hydraulic action, abrasion, FTW and rockfalls occur.

Cliff retreats, wave cut platform develops and build up in beach material - sand.

24
Q

What is a blow hole

A

Roof of cave collapses, incoming waves force air to rush vertically or water to spout intermittently

25
Q

What is a geo

A

Inlet in face of cliff - created by the wave driven erosion of cliffs along faults and bedding planes in rock

26
Q

Long shore drift

A

Sediment is carried up beach by awash and backwash

27
Q

Solution

A

Minerals dissolved in sea water

28
Q

Suspension

A

Small particles carried in water

29
Q

Saltation

A

Load bounced along sea bed - small pieces of shingle

30
Q

Traction

A

Pebbles/ larger sediments rolled along sea bed

31
Q

Formation of spit

A

Spit is stretch of land that joins the main beach at one end

Long shore drift and direction of prevailing wind, sediments carried up beach by smash and backwash. Deposited above the high water mark and becomes short extension of beach material connected to main beach.

Longer spit created, second most dominant wind creates hook. Fastest river current helps prevent spit from expanding to form a bar. Behind spit - mud flat forms. When conditions become possible for algae and vegetation to grow, salt marshes form.

Salt marshes can act as a natural coastline defence, trapping sediments and creating shallows near coast - slow down and remove energy from storm waves.

32
Q

Coastal management (7)

A

Sea wall - Built along front of cliff to protect settlement
Groynes - To help prevent longshore drift
Offshore rock groynes - Change direction of waves and reduce longshoremen drift
Rip rap/ rock armour - Big boulders Placed along base of cliff to absorb energy from waves
Revetments - Wooden slatted barrier absorbs energy from waves
Gabbions - Rocks and boulders invaded in wired mesh to absorb energy from waves
Beach replenishment - Making beaches higher and wider by bringing sand in from somewhere else