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OCR A level Geography > Coasts KQ2- formation of landforms > Flashcards

Coasts KQ2- formation of landforms Flashcards

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1
Q

Describe what a wave cut platform is

A

A flat, gently sloping horizontal areas of rock found at the base of cliffs

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2
Q

Describe what a cliff is

A

Near vertical faces of exposed rock, where the sea meets the land

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3
Q

Give an example of an area where cliffs and wave cut platforms are found

A

Broad bench, Kimmeridge, Dorset

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4
Q

Outline how wave cut platforms are formed

A
  • waves erode the base of a cliff by abrasion, hydraulic action, pounding
  • This leads to undercuttin and formation of a wave-cut notch
  • Eventually unsupported rock collapses
  • The collapsed cliff material is washed away by waves
  • Cliffs retreat as this occurs repeatedly
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5
Q

Describe what a wave-cut notch is

A

A small indent at the base of a cliff

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6
Q

Describe what bays are

A

bodies of water which are surrounded by land on three sides

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7
Q

Define weathering

A

The in-situ disintegration of rock by chemical, biological, and physical processes

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8
Q

How does physical weathering allow other weathering to take place?

A

Physical weathering breals rock into smaller pieces, which increases the surface area for other weathering to take place

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9
Q

Give 4 examples of physical weathering

A
  • Freeze-thaw weathering
  • Pressure release
  • Thermal expansion
  • Salt crystalisation
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10
Q

Describe the process of freeze-thaw weathering

A
  • water enters cracks and freezes
  • when water freezes it expands
  • expansion of water causes pressure on rocks
  • this can split even resistant rock and cause pieces to break off
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11
Q

Describe the process of pressure release weathering

A
  • Overlying rocks are removed by weathering and erosion releasing pressure on rock
  • Underlying rock expands and fractures
  • Causing parallel fractures to form
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12
Q

Describe the process of thermal expansion weathering

A
  • Rocks experience repeated cycles of temperature change
  • When rock is heated it expands, and when it is cooled it contracts
  • This causes the outer layers of rock to crack and flake off
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13
Q

Describe the process of salt crystallisation

A
  • Salts precipitate and form crystals in pore spaces in rocks
  • This causes pressure within the rock
  • Causing rock to disintegrate
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14
Q

Which salts are particuarly effective at salt crystallisation weathering?

A

Sodium sulfate and sodium carbonate

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15
Q

What is chemical weathering?

A

Weathering which involves reactions between moisture and some minerals within the rock

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16
Q

Name 5 examples of chemical weathering

A
  • Oxidation
  • Carbonation
  • Solution
  • Hydrolysis
  • Hydration
17
Q

Describe the process of oxidation weathering

A
  • Minerals in rock react with oxygen from air or water
  • The original structure of the rock is destroyed and disintegrated
18
Q

Which type of rock is particularly susceptible to oxidation?

A

Sandstone- as it contains a high % of Iron

19
Q

Describe the process of carbonation

A
  • Rainwater reacts with dissolved carbon dioxide to produce weak carbonic acid
  • The carbonic acid reacts with calcium carbonate to produce calcium bicarbonate
  • Calcium bicarbonate is soluble in water
  • Rocks containing calcium carbonate are dissolved
20
Q

Describe the process of solution (as a weathering process)

A
  • Some salts are soluble in water or in specific conditions
  • Rock minerals dissolve, reducing the size of rocks
  • The structural integrity of the rock can be undermined
21
Q

Describe the process of hydrolysis (weathering)

A
  • Silicates combine with water, reacting chemically to produce clays
  • The secondary minerals that are produced are much softer than the original rock
  • The rock can be eroded more easily
22
Q

Describe the process of hydration (weathering)

A
  • When water reacts with rocks new minerals are created
  • The new minerals have a larger volume than the original rocks
  • This causes pressure to be exerted
  • Surface flaking of rock occurs
23
Q

What is biological weathering?

A

Weathering which may consist of physical or chemical processes but these are crucially as a result of the action of living organisms

24
Q

Give 2 examples of biological weathering

A
  • Tree root weathering
  • Organic acids/chelation
25
Q

Describe the process of tree root weathering

A
  • Tree roots grow into cracks and exert pressure
  • If these trees topple they act as a lever
  • Pressure exerted on cracks can expand fissures in the rock
  • Trees toppling bring soils and rock to the surface allowing them to be weathered further
26
Q

Describe the process of chelation (weathering)

A
  • Molluscs secrete acids
  • Decomposition of plant and animal litter can cause soil water to become acidic
  • Acidic soil reacts with some minerals
  • Molluscs cause small surface hollows in rock
27
Q

Define mass movement

A

The downslope transportation of material under gravity

28
Q

What are the factors that affect mass movement?

A
  • amount of water
  • vegetation
  • marine processes/wave action
29
Q

What are the 3 categories that mass movements can be split into?

A
  • Fast
  • Slow
  • Flow
30
Q

Give an example of flow mass movement

A

Mudflow

31
Q

Give 3 examples of fast mass movement

A
  • Rock slide
  • Rock fall
  • Slumping
32
Q

Give 2 examples of slow mass movement

A
  • Soil creep
  • Rain splash
33
Q

Describe the process of soil creep

A
  • Individual soil particles are pushed down or heaved to the surface by wetting, heating, or freezing
  • Soil particles move at right angles to the surface
  • When dry soil particles move under the influence of gravity
34
Q

Describe the process of rain splash (mass movement)

A

When a raindrop falls on soil it dislodges soil particles

35
Q

Describe the process of mudflow

A
  • Material on a slope becomes saturated with water, making it much heavier
  • Material moves down a slope in the form of a fluid
  • Most likely to occur after intense rainfall
36
Q

What geology makes a slope vulnerable to mudflow?

A

Thin soils overlying impermeable rock

37
Q

Describe the process of rock slides

A
  • Rocks have jointing or bedding planes roughly parallel to the angle of the slope
  • Once weathered, large blocks of rock can slide downhill
38
Q

Describe the process of rockfalls

A
  • Occur on slopes in excess of 40°
  • Can result from extreme physical or chemical weathering, storm action, or earthquakes
  • Bits of rock fall off the cliff face
  • Material that accumulates at the base is called tallus/scree
39
Q

Describe the process of rotational slumping

A
  • Saturated soil slumps down a curved surface
  • Occur where weaker rocks/clays overlay more resistant or impermeable rock
  • Creates curved slip planes

OCR A level Geography (31 decks)

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