Marine coastal erosion Flashcards
What is hydraulic action?
The impact on rocks from the force of the water itself (without debris), exerting pressure on the rock and thus weakening it.
What is wave quarrying?
When a breaking wake traps air as it hits the cliff face, the water compresses air into gaps and cracks in the rock face. As the water pulls back there is an explosive effect which in turn weakens the cliff face. Storms may also remove large chunks at a time.
What is abrasion/corrasion?
Material from the sea wearing away rocks on the cliff face. Sand, shingle and boulders can be hurled at the cliff from the sea in a sort of sandpaper effect.
What is attrition?
Rocks carried out by sea slowly worn down becoming more rounded and smooth.
What is solution?
Dissolving of calcium-based rocks (e.g limestone). Waters with a pH lower than 7 can corrode rocks due to their slight acidity.
Effects of evaporation on rocks to produce salt crystals can expand when forming and put stress upon rocks .
Name 3 things that affect coastal erosion.
(Any 3 of these 6)
Wave steepness/breaking point
Fetch
Sea depth
Coastal configuration
Beach prescence
Human activity
How does wave steepness/breaking point affect coastal erosion?
Steeper, and higher evergy waves have a greater erosive affect. Waves that break at the foot of a cliff release more energy than those further out to sea.
How does the Fetch affect coastal erosion?
How far the wave travels determined how much energy is generated.
How does sea depth affect coastal eroison?
A steeply shelving sea bed at the coast will create higher and steeper waves.
How does coastal configuration affect coastal erosion?
Headlands attract wave energy through wave refraction.
How does a beach prescence affect coastal erosion?
Beaches absorb wave energy and therfore provide protection.
Steep, narrow beaches easily dissipate energy from flatter waves.
Wider, flatter beaches spread out incoming wave energy and are best for dissipating high and rapid energy inputs.
Shingle beaches rapidly dissipate wave energy through percolation and friction.
How does human activity affect coastal erosion?
People may remove protective materials (sand and shingle) which can increase erosion.
Sea defences can heavily halt or reduce erosion. (May lead to increased coastal erosion elsewhere).
Whats the difference between marine processes and sub-aerial processes?
Marine processes operate upon a coastline and are connected to the sea (e.g longshore drift, waves, and tides).
Sub-aerial processes operate on the land but affect the shape of the coastline (e.g weathering, mass movement, and run-off).
