Marine Erosion: Processes, Rates and Transportation

Question 1

What are the 6 marine erosional processes?

Answer 1

Hydraulic action
Wave pounding
Wave quarrying
Attrition
Solution (corrosion)
Abrasion (corrasion)

Question 2

What is hydraulic action?

Answer 2

This is essentially wave pounding: the force of the water on the rocks.

Question 3

What is wave pounding?

Answer 3

This is the sledgehammer effect of the water on the rocks which weakens the cliff.

Question 4

What is wave quarrying?

Answer 4

This is where water traps and compresses air which exerts pressure on the rock. As the wave pulls back, there is an explosive effect as air is released which weakens the rock.

Question 5

What is abrasion/ corrasion?

Answer 5

This is were sand, shingle and boulders are picked up by the sea and hurled at the cliff.

Question 6

What is attrition?

Answer 6

This is the wearing down of rocks and pebbles as they rub against each other, making them smaller and rounder.

Question 7

What is solution/ corrosion?

Answer 7

This is where fresh water mixes with salt water, potentially causing it to increase its acidity and therefore wear down carbon based rocks.

Question 8

What are the 6 factors that affect the rate of marine erosion?

Answer 8

Wave steepness and breaking point
Fetch
Sea depth
Human activity
Beach presence
Coastal configuration

Question 9

How does wave steepness affect the rate of marine erosion?

Answer 9

The steeper the wave, the more energy it has and the more erosive power that it has.

Question 10

How does the breaking point of the wave affect the rate of marine erosion?

Answer 10

Waves that break at the foot of the cliff release more energy than those that break some distance from the shore.

Question 11

What is fetch?

Answer 11

Fetch is how far the wave has travelled, this determines how much energy is generated. The further the distance, the more energy that is generated due to the wind and so the more erosive power.

Question 12

How does sea depth affect the rate of marine erosion?

Answer 12

A steeply shelving seabed will create higher and steeper waves.

Question 13

How does coastal configuration affect the rate of marine erosion?

Answer 13

Headlands attract wave energy by refraction.

Question 14

What two human activities affect the rate of marine erosion?

Answer 14

Building sea defences

Removing beach material

Question 15

What type of beach dissipates energy from flatter waves?

Answer 15

Steep, narrow beaches dissipate energy from flatter waves.

Question 16

How do shingle beaches dissipate wave energy?

Answer 16

They do this by percolation and friction.

Question 17

What do flat, wide beaches do to wave energy?

Answer 17

Flat, wide beaches spread out wave energy, especially from rapid, high energy waves.

Question 18

What are the five processes of marine transportation?

Answer 18

Traction
Saltation
Suspension
Solution
Long shore drift

Question 19

What is traction?

Answer 19

This is where large stones and boulders are rolled and slid along the seabed and beach by moving sea water.

Question 20

Where does traction occur?

Answer 20

It occurs in high energy environments.

Question 21

What is saltation?

Answer 21

This is where small stones bounce along the seabed and beach. When they land they dislodge other particles.

Question 22

Where does saltation occur?

Answer 22

It occurs in high energy environments.

Question 23

What is suspension?

Answer 23

This is where very small sand and silt particles are picked up and carried by the moving water, causing the sea to look milky or murky.

Question 24

What is solution?

Answer 24

This is where dissolved materials are transported within the mass of the moving water.

Question 25

What does long shore drift combine?

Answer 25

It combines the 4 main processes of marine transportation.

Question 26

How does long shore drift work?

Answer 26

Waves approach the shore at an angle.
Swash pushes material up the beach at the same angle as the wave and prevailing wind.
The backwash drags sediment back down the beach at the steepest gradient which is usually perpendicular.
The following incoming wave picks up the sediment and the process repeats itself.

Question 27

When does marine deposition occur?

Answer 27

This occurs when sand and shingle accumulate faster than they are removed.
Waves slow following breaking.
Water pauses at the top of the swash before the backwash begins.
When water percolates into the beach material as backwash takes it back down the beach.