Marine Erosion: Processes, Rates and Transportation Flashcards
What are the 6 marine erosional processes?
Hydraulic action Wave pounding Wave quarrying Attrition Solution (corrosion) Abrasion (corrasion)
What is hydraulic action?
This is essentially wave pounding: the force of the water on the rocks.
What is wave pounding?
This is the sledgehammer effect of the water on the rocks which weakens the cliff.
What is wave quarrying?
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.
What is abrasion/ corrasion?
This is were sand, shingle and boulders are picked up by the sea and hurled at the cliff.
What is attrition?
This is the wearing down of rocks and pebbles as they rub against each other, making them smaller and rounder.
What is solution/ corrosion?
This is where fresh water mixes with salt water, potentially causing it to increase its acidity and therefore wear down carbon based rocks.
What are the 6 factors that affect the rate of marine erosion?
Wave steepness and breaking point Fetch Sea depth Human activity Beach presence Coastal configuration
How does wave steepness affect the rate of marine erosion?
The steeper the wave, the more energy it has and the more erosive power that it has.
How does the breaking point of the wave affect the rate of marine erosion?
Waves that break at the foot of the cliff release more energy than those that break some distance from the shore.
What is fetch?
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.
How does sea depth affect the rate of marine erosion?
A steeply shelving seabed will create higher and steeper waves.
How does coastal configuration affect the rate of marine erosion?
Headlands attract wave energy by refraction.
What two human activities affect the rate of marine erosion?
Building sea defences
Removing beach material
What type of beach dissipates energy from flatter waves?
Steep, narrow beaches dissipate energy from flatter waves.
How do shingle beaches dissipate wave energy?
They do this by percolation and friction.
What do flat, wide beaches do to wave energy?
Flat, wide beaches spread out wave energy, especially from rapid, high energy waves.
What are the five processes of marine transportation?
Traction Saltation Suspension Solution Long shore drift
What is traction?
This is where large stones and boulders are rolled and slid along the seabed and beach by moving sea water.
Where does traction occur?
It occurs in high energy environments.
What is saltation?
This is where small stones bounce along the seabed and beach. When they land they dislodge other particles.
Where does saltation occur?
It occurs in high energy environments.
What is suspension?
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.
What is solution?
This is where dissolved materials are transported within the mass of the moving water.
What does long shore drift combine?
It combines the 4 main processes of marine transportation.
How does long shore drift work?
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.
When does marine deposition occur?
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.
