Coastal processes

Question 1

What are sub-aerial processes

Answer 1

Land-based processes which alter the shape of a coastline.

Question 2

What is weathering

Answer 2

Breakdown of rock in situ

Question 3

What is Physical weathering

Answer 3

Disintegration, eg the break up of rock first into larger blocks and eventually into smaller grains, with no chemical change.

Question 4

What is chemical weathering

Answer 4

Decomposition of rocks, eg the separating of the minerals found in the rock.

Question 5

What is salt crystal growth

Answer 5

Occurs when saline solutions enter the rock pores or cracks and evaporate which leaves behind salt crystals. When this happens repeatedly, the salt builds up and the crystal expands. As they expand, they exert pressure on the rocks which eventually causes the rock to disintegrate.

Question 6

What is Carbonation

Answer 6

The process by which rocks that contain calcium carbonate are broken down. Co2 dissolves into rainwater to produce a weak carbonic acid rain which reacts with the calcium carbonate causing the formation of calcium bicarbonate. This dissolves in water.

Question 7

What is oxidation

Answer 7

Rusting, whereby the rock minerals lose one or more ions in the presence of oxygen, when they oxidise they break down.

Question 8

What is Chelation

Answer 8

Organic acids are released when organic matter decomposes, these acids cause the removal of metallic cations from minerals in rocks, causing them to break down.

Question 9

What is frost wedging

Answer 9

Occurs when water enters cracks in the rocks, when it freezes it expands by 9% which forces the cracks to widen, eventually rock shatters.

Question 10

What is mass movement

Answer 10

The downslope movement of regolith ( weathered material) under the influence of gravity

Question 11

What is the shear strength

Answer 11

Forces holding a slope in place

Question 12

What is shear stress

Answer 12

Forces drawing materials downslope eg gravity or mass

Question 13

Causes of mass movement

Answer 13

Removal of vegetation- Less interception so more water in soil, heavier mass, so increased shear stress. Less friction so less sheer strength.
Weathering- Breakdown of rock, changing the binding, reducing cohesion between particles, so sheer strength decreases.

Question 14

What is rockfall

Answer 14

Material breaks up and falls in pieces usually associated with nearly vertical slopes. Only more resistant rock can sustain these angles

Question 15

What is slumping

Answer 15

Downward movement of unconsolidated rock debris that’s usually caused by the removal of the earth at the foot of a slope.

Question 16

What is soil creep

Answer 16

1-2cm per year, occurring on very gentle slopes. soil particles repeatedly expand and contract in wet and dry periods. When wet, soil particles increase in size and weight, and expand at right angles to the slope. When the soil dries out, it contracts vertically and is drawn downslope.

Question 17

What is rock type

Answer 17

Refers to the characteristics of the rocks in particular the resistance and permeability.

Question 18

What is presentation

Answer 18

How the rocks present themselves to the coast, concordant or discordant

Question 19

Factors affecting marine erosion

Answer 19

-Sub-aerial processes, e.g weathering.
-Wind fetch
-Geology of rock
-Beach pressure and character.

Question 20

What is abrasion

Answer 20

Abrasion is when rocks and other materials carried by the sea are picked up and hurled by strong waves against the coastline, causing material to be broken off and carried away by the sea.

Question 21

What is hydraulic action

Answer 21

The sheer force of water crashing against the coastline, causing material to be dislodged and carried away by the sea.

Question 22

What is cavitation

Answer 22

Air bubbles trapped in the water get compressed into small spaces like cracks in the cliff. These bubbles implode as waves break, creating a small shockwave that weakens the rock.

Question 23

What is attrition

Answer 23

Individual sediment particles collide with each other

Question 24

What is wave quarrying

Answer 24

When high energy, tall waves hit cliff with power to enlarge joints and remove sediment.