Geomorphological processes

Question 1

What is the main acting agent that leads to cliff collapse?

Answer 1

Weathering

Question 2

What are the three types of weathering?

Answer 2

• Chemical
• Physical
• Biological

Question 3

Define weathering

Answer 3

It’s the wearing away of rocks in situ.

Question 4

Define chemical weathering

Answer 4

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

Question 5

Define physical weathering

Answer 5

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

Question 6

Define biological weathering

Answer 6

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

Question 7

What are the 6 types of erosion?

Answer 7

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

Question 8

Define hydraulic action

Answer 8

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

Question 9

Define quarrying

Answer 9

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 10

Define cavitation

Answer 10

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

Question 11

Define abrasion

Answer 11

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

Question 12

Define solution

Answer 12

Chalk and limestone is dissolved and rock is removed in solution.

Question 13

Define attrition

Answer 13

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

Question 14

Define mass movement

Answer 14

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

Question 15

What 5 factors affect mass movement?

Answer 15

• Rainfall
• Rock type
• Human activity
• Vegetation cover
• Angle of the slope

Question 16

What is cliff slumping?

Answer 16

The rapid movement of a mass of earth or rock sliding along a concave surface.

Question 17

Describe the 3 stages of cliff slumping

Answer 17

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 18

Define traction

Answer 18

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

Question 19

Define suspension

Answer 19

Small particles like silt and clay are carried along in the water

Question 20

Define saltation

Answer 20

Pebble sized particles are bounced along the sea bed by the force of the water

Question 21

Define solution

Answer 21

Soluble materials dissolve in the water and are carried along

Question 22

How does a mudslide occur?

Answer 22

When saturated soil and weak rock flows down a slope.
Typically occurs when cliffs are made up of boulder clay

Question 23

What is a rockfall

Answer 23

Involves fragments of rock breaking away from the cliff face, often due to freeze-thaw weathering.

Question 24

When does a landslide occur?

Answer 24

When waves break at the foot of a cliff - causing erosion. This creates a wave-cut notch and as this increases in size the weight of the cliff becomes too much to support - causing a landslide to occur.