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Costal environments - year 2 geog > Coastal processes > Flashcards

Coastal processes Flashcards

1
Q

What is the difference between weathering and erosion?

A

Weathering is the wearing away of rocks, whereas erosion is the breakdown and subsequent removal and transportation of material. It is usually caused by the direct action of the sea on the shore

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2
Q

What are the 3 main types of weathering?

A

Physical/mechanical
Chemical
Biological

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3
Q

What is physical/mechanical weathering?

A

Internal pressures are exerted on rock as a result of changes in the physical structure within its mass

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4
Q

What is chemical weathering?

A

Both rain and seawater contain chemicals that can react with chemical compounds in the rock, altering its structure

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5
Q

What is biological weathering?

A

Living organisms can contribute to the weathering of coastal rocks through the activity of plants and animals

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6
Q

What are the types of physical/mechanical weathering?

A

Wetting and drying
Exfoliation
Crystallisation
Freeze thaw

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7
Q

What are the types of chemical weathering?

A

Carbonation
Oxidation

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8
Q

What are the types of biological weathering?

A

Plant roots
Animals

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9
Q

What are the types of erosion?

A

Hydraulic action, quarrying, cavitation, abrasion, solution and attrition

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10
Q

What is hydraulic action?

A

Waves break against a cliff face and water forces itself into cracks - compressing the air inside. Sheer force of the water

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11
Q

What is quarrying?

A

Destructive waves in storm conditions plunge heavy hydraulic pressure on cliff faces. The vibration of the cliff can dislodge bits of rock and undercuts the base of the cliff

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12
Q

What is cavitation?

A

The opening up of cavities within cliffs due to changes in pressure as waves crash into and out of cracks in the rock

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13
Q

What is abrasion/corrasion?

A

The launching of rock fragments and pebbles against cliffs by waves can break off pieces of solid cliff and weaken rock structure

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14
Q

What is solution/corrosion?

A

Chalk and limestone is dissolved and rock is removed in solution

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15
Q

What is attrition?

A

The smoothing and reducing of angular rock fragments into pebbles, shingle and eventually sand particles

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16
Q

What is mass movement?

A

The movement of consolidated material (solid rock) and unconsolidated material (clay and soil) due to gravity

17
Q

What are the factors that affect mass movement?

A

Rainfall
The nature of the material
The angle of the slope
Vegetation cover
Human activity

18
Q

What is cliff slumping?

A

Cliffs are shaped through a combination of erosion and weathering - the breakdown of rocks caused by weather conditions

19
Q

What cliffs are prone to erosion?

A

Cliffs formed from soft material (e.g. boulder clay)

20
Q

Why is boulder clay and soft materials prone to erosion?

A

During dry weather clay cracks and contracts; when it rains water is absorbed into the cracks until it becomes saturated - this weakens the rock and causes it to slip down the slope on its slip plane

21
Q

How is the soft boulder eroded?

A

At the base by hydraulic action and corrosion

22
Q

How does weathering cause cliff slumping?

A

Rainfall. This often happens where layers of boulder clay become saturated and cause the cliff to slump

23
Q

What are the stages of cliff slumping?

A

Stage 1 - The soft boulder clay holds rainwater
Stage 2 - Waves erode the base of the cliff creating a wave cut notch
The clay becomes saturated and forms a slip plane
Stage 3 - The weight of the saturated cliff causes it to slump

24
Q

What is a wave cut notch?

A

When erosion occurs at the base of a cliff, due to cliff material being more resistant as erosion is greatest when waves break at the foot of a cliff

25
Q

When does a landslide occur in coastal environments?

A

As a wave cut notch increases in size, the weight of the cliff above becomes too much to support - this leads to a landslide

26
Q

How can a coastal landslide be a temporary benefit?

A

The material from the landslide will provide temporary protection for the cliff behind. However, once it has been removed by the sea this process will occur again.

27
Q

How are wave cut platforms created?

A

After a landslide has occurred, the backwash carries away the eroded material, leaving a wave cut platform

28
Q

What is rockfall?

A

A rockfall involves fragments of rock breaking away from the cliff face, often due to freeze thaw weathering

29
Q

What is a mudslide?

A

Mudslides occur when saturated soil and weak rock flows down a slope. These typically occur where cliffs are made up of boulder clay

30
Q

What are the energy factors that affect the rate of erosion?

A

Waves
Tides
Currents
Winds

31
Q

What are the material factors that affect the rate of erosion?

A

Sediment supply
Beach/rock platform width
Rock resistance
Rock structure and dip

32
Q

What are the shore geometry factors affecting the rate of erosion?

A

Offshore topography
Orientation of coast
Direction of fetch

Costal environments - year 2 geog (10 decks)

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