Coastal processes

Question 1

What is the difference between weathering and erosion?

Answer 1

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

Question 2

What are the 3 main types of weathering?

Answer 2

Physical/mechanical
Chemical
Biological

Question 3

What is physical/mechanical weathering?

Answer 3

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

Question 4

What is chemical weathering?

Answer 4

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

Question 5

What is biological weathering?

Answer 5

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

Question 6

What are the types of physical/mechanical weathering?

Answer 6

Wetting and drying
Exfoliation
Crystallisation
Freeze thaw

Question 7

What are the types of chemical weathering?

Answer 7

Carbonation
Oxidation

Question 8

What are the types of biological weathering?

Answer 8

Plant roots
Animals

Question 9

What are the types of erosion?

Answer 9

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

Question 10

What is hydraulic action?

Answer 10

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

Question 11

What is quarrying?

Answer 11

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

Question 12

What is cavitation?

Answer 12

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

Question 13

What is abrasion/corrasion?

Answer 13

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

Question 14

What is solution/corrosion?

Answer 14

Chalk and limestone is dissolved and rock is removed in solution

Question 15

What is attrition?

Answer 15

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

Question 16

What is mass movement?

Answer 16

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

Question 17

What are the factors that affect mass movement?

Answer 17

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

Question 18

What is cliff slumping?

Answer 18

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

Question 19

What cliffs are prone to erosion?

Answer 19

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

Question 20

Why is boulder clay and soft materials prone to erosion?

Answer 20

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

Question 21

How is the soft boulder eroded?

Answer 21

At the base by hydraulic action and corrosion

Question 22

How does weathering cause cliff slumping?

Answer 22

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

Question 23

What are the stages of cliff slumping?

Answer 23

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

Question 24

What is a wave cut notch?

Answer 24

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

Question 25

When does a landslide occur in coastal environments?

Answer 25

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

Question 26

How can a coastal landslide be a temporary benefit?

Answer 26

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.

Question 27

How are wave cut platforms created?

Answer 27

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

Question 28

What is rockfall?

Answer 28

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

Question 29

What is a mudslide?

Answer 29

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

Question 30

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

Answer 30

Waves Tides Currents Winds

Question 31

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

Answer 31

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

Question 32

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

Answer 32

Offshore topography Orientation of coast Direction of fetch