Geography A-Level - Physical - Coastal Processes
- Created by: Noah_S
- Created on: 18-06-21 16:58
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- Coastal Processes
- Weathering
- Chemical
- Hydrolysis - Slight acidic rainwater reacts with minerals in the rock, degrading the rock
- Hydration - Water added to materials in the rock, causing it to expand, creating stress
- Carbonation - Carbon dioxide in rainwater reacts with calcium carbonate like in limestone, creating calcium bicarbonate which dissolves
- Oxidation - Causes rocks to disintegrate when oxygen interacts with iron-rich rocks
- Physical
- Freeze-Thaw - Water enters a crack, where it freezes and expands by 9% of it's volume, which widens & deepens the crack, before thawing and repeating
- Wetting & Drying - Rocks such as shale expand greatly when wetted, and contract on drying, causing pressure to be exerted on the rock
- Exfoliation - Rocks may expand due to heat, and when they are cooled rapidly with seawater pressure is exerted on the rock
- Biological
- Combination of Physical and Chemical weathering
- Physical Examples; Marine organisms drilling into rock, Tree roots cracking open joints, Vegetation attaching itself to rocks, causing it to sway in the waves
- Chemical Examples; Algae secreting chemicals capable of promoting solution
- Chemical
- Mass Movement
- Mudflows
- Heavy rain can cause a large amount of fine material to flow downhill
- E.g. Soil becoming saturated and if the water cannot percolate deeper, the ground surface layers become very fluid and flow downhill
- Landslides
- Occurs on cliffs made up from softer rocks or deposited material, which slip because of failure within it or lubricated by rainfall
- Rotational Slump
- Where softer material overlies more resistive material, excessive lubrication causes whole sides of the cliff to move downward with a slide plane
- Rock Falls
- Occurs from cliffs undercut by the sea, or on slopes affected by mechanical weathering
- Mudflows
- Erosion
- Abrasion
- Debris from the cliff being hurled against the cliff by waves
- Attrition
- Debris impacting each other in the sea, making themselves smaller and more rounded
- Wave Quarrying
- Waves compressing air into fissures on the cliff, creating an explosive effect when released
- Solution
- Calcium-based rocks are dissolved by rainwater, which is acidic compared to the alkaline seawater
- Hydraulic Action
- The force of the water itself impacting on the coastline
- Abrasion
- Weathering
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