Coastal Zone: Coastal Weathering Flashcards
What is erosion?
Erosion is when the rocks are broken down and CARRIED AWAY by something such as sea water.
What is weathering?
Weathering is the breakdown of rocks where they are.
What is mechanical weathering?
Mechanical weathering is the breakdown of rock without changing its chemical composition. eg- freeze thaw weathering.
What are the conditions for freeze-thaw weathering?
- Temperature alternates above and below 0 degrees.
- Water gets into cracks. Eg granite.
- When the water freezes it expands which puts pressure on the rock.
- When the water thaws it contracts which releases the pressure.
- Repeated freezing and thawing widens the cracks and causes the rocks to break up.
What is chemical weathering?
Chemical weathering is the breakdown of rock AND changing its chemical composition. Eg- carbonation.
What is carbonation?
Carbonation is when rainwater had carbon dioxide dissolved into it which makes a weak carbonic acid.
Carbonic acid reacts with rock that contains calcium carbonate. Eg- limestone so the rocks are dissolved by the rainwater
What is mass movement?
Mass movement is when material shifts down a slope as one.
What are the steps involved in mass movement?
- Mass movement is the shifting of lose material down a slope when then force of gravity is greater than the force supporting it.
- Mass movement causes coasts to retreat rapidly
- It’s more likely to occur if the material is full of water as it acts as a lubricant.
- There is two types of mass movement: slides and slumps
What are the two types of mass movement?
Slides- when material shifts in a straight line.
Slumps- when material shifts with a rotation.
What are the four processes of erosion?
- Hydraulic power
- Abrasion
- Attrition
- Solution
What happens in hydraulic power?
Waves crash against rock and compress the air in the cracks. This puts pressure on the rocks. Repeated compressions widen the cracks and make bits fall of.
What happens in abrasion?
Eroded particles in the water scrape and rub against the rock removing small pieces.
What happens in attrition?
Eroded particles in the water smash into each other and break into smaller fragments. Their edges get rounder off as they rub together.
What happens in solution?
Weak carbonic acid in seawater dissolves rock like chalk and limestone.
What are waves that carry out erosion processes?
Destructive waves
