COASTS: Coastal Processes

Question 1

What are the processes of erosion?

Answer 1

1. Abrasion (corrasion)
2. Hydraulic action
3. Cavitation
4. Wave quarrying
5. Solution (corrosion)
6. Attrition

Question 2

Abrasion (corrasion)

Answer 2

Rock and sediment transported by the waves smash against he rocks and cliffs, breaking bits off and smoothing the surfaces.

Question 3

Hydraulic action

Answer 3

Air in cracks in cliffs is compressed when waves crash in.

Pressure exerted by the compressed air breaks off rock pieces.

Question 4

Cavitation

Answer 4

As waves recede, the compressed air expands violently, again exerting pressure on the rock and causing pieces to break off.

Question 5

Wave quarrying

Answer 5

The energy of a wave as it breaks against a cliff is enough to detach rock.

Question 6

Solution (corrosion)

Answer 6

Soluble rocks get gradually dissolved by the seawater.

Question 7

Attrition

Answer 7

Rock and sediment in the water smash against each other and breaks into smaller pieces.

Question 8

Rock and sediment transported by the waves smash against he rocks and cliffs, breaking bits off and smoothing the surfaces.

Answer 8

Abrasion (corrasion)

Question 9

Air in cracks in cliffs is compressed when waves crash in.

Pressure exerted by the compressed air breaks off rock pieces.

Answer 9

Hydraulic action

Question 10

As waves recede, the compressed air expands violently, again exerting pressure on the rock and causing pieces to break off.

Answer 10

Cavitation

Question 11

The energy of a wave as it breaks against a cliff is enough to detach rock.

Answer 11

Wave quarrying

Question 12

Soluble rocks get gradually dissolved by the seawater.

Answer 12

Solution (corrosion)

Question 13

Rock and sediment in the water smash against each other and breaks into smaller pieces.

Answer 13

Attrition

Question 14

What are the processes of transportation?

Answer 14

1. Solution
2. Saltation
3. Suspension
4. Traction

Question 15

Solution

Answer 15

Substances dissolve and are carried along in the water.

Eg. limestone dissolved in acidic water.

Question 16

Saltation

Answer 16

The force of the water causes larger particles to bounce along the sea bed.

Question 17

Suspension

Answer 17

Very fine material is whipped by turbulence and carried in the water.

Most common transportation in coastal systems.

Question 18

Traction

Answer 18

Large particles are pushed along the sea bed by the force of water.

Question 19

Substances dissolve and are carried along in the water.

Eg. limestone dissolved in acidic water.

Answer 19

Solution

Question 20

The force of the water causes larger particles to bounce along the sea bed.

Answer 20

Saltation

Question 21

Very fine material is whipped by turbulence and carried in the water.

Most common transportation in coastal systems.

Answer 21

Suspension

Question 22

Large particles are pushed along the sea bed by the force of water.

Answer 22

Traction

Question 23

Marine deposition

Answer 23

Sediment carred by seawater is deposited.

Question 24

Aeolion depostion

Answer 24

Sediment carried by the wind is deposited.

Question 25

Give two reasons why wind or water might slow down:

Answer 25

1. Friction increases 2. Flows becomes turbulent

Question 26

Sub-aerial weathering

Answer 26

The gradual break down or rock by agents such as ice, salt, plants roots and acids.

Question 27

What are the different types of weathering?

Answer 27

Chemical Mechanical Biological

Question 28

What are the different types of chemical weathering?

Answer 28

Carbonation Oxidation

Question 29

What are the different type of mechanical weathering?

Answer 29

Freeze-thaw Salt crystallisation Wetting and drying Exfoliation

Question 30

Biological weathering

Answer 30

Growing plant roots widen cracks.

Question 31

Sub-aerial processes

Answer 31

Land based processes that consist of weathering and mass movement.

Question 32

Carbonation

Answer 32

Sea and rain absorb carbon dioxide forming carbonic acid which then dissolves the calcium carbonate in rocks, such as limestone or chalk, into calcium bicarbonate.

Question 33

Oxidation

Answer 33

Rocks containing iron (ferrous) compounds experience this when turned into a ferric state when oxygen and water are available, leading to disintergration.

Question 34

Salt crystallisation

Answer 34

* Saline (salty) water enters pores or cracks in rocks at high tide. * As the tide goes out the rocks dry and water evaporates. * Salt crystals form and expand. * Puts pressure on the rock causing pieces to break off.

Question 35

Chemical weathering

Answer 35

The breakdown of rock by changing its chemical composition.

Question 36

Freeze-thaw

Answer 36

* Water enters the joints and crevices in rocks. * When temperature drops below 0^oC, this water freezes and expands. * Overtime, repeated freeze-thaw action weakend the rocks and causes pieces to fall off.

Question 37

Wetting and drying

Answer 37

* Clay/shale expands when wet and contracts when dry. * Creates cracks that are vulnerable. * Fragments break off.

Question 38

Exfoliation

Answer 38

* Rock under considerable heat will expand. * Sea cools this rock causing rapid contraction. * This repeated process causes the outer layer to crack and peel off.

Question 39

Mass movement

Answer 39

The shifting of material downhill due to gravity.

Question 40

When is freeze-thaw weathering likely to occur?

Answer 40

In areas where temperatures fluctuate above and below freezing.

Question 41

When is mass movement most likely to occur in coastal areas?

Answer 41

When the cliffs are undercut by wave action causing an unsupported overhang.

Question 42

Give some examples of mass movement:

Answer 42

Soil creep Rotational slumping Rock falls Landslides Mudflows Runoff

Question 43

Soil creep

Answer 43

Slow, gradual movement of material downhill.

Question 44

Rotational slumping

Answer 44

Material shifts down with a rotation.

Question 45

What is rotational slumping caused by?

Answer 45

* Heavy rain infiltrates unconsolidated soil. * Impermeable soil layer traps water - adds weight. * Undercutting causes collapse on slip plane.

Question 46

What type of rocks are prone to collapse? Why?

Answer 46

Unconsolidated rocks. There is little friction between particles to hold them together.