Coasts Flashcards
Name the processes that happen at the coast
- Weathering
- Transportation
- Erosion
What is Mechanical weathering
The breakdown of rock at without changing it chemical composition
Process of Mechanical weathering
- Water fills a crack or joint
- Water freezes -> crack is widened (pressure)
- Repeated FREEZE-THAW-ACTION increases the size of the rock
- Block of rock falls off, loose blocks are called scree
What is Chemical weathering
The breakdown of rock by changing its chemical composition
- Warm wet conditions
Process of Chemical weathering
- Rainwater has co2 dissolved in it -> weak carbonic acid
2. Reacts with rock that contains calcium carbonate, wears away the rock
Process of Biological weathering
- Roots of vegetation grow in cracks
- Splits the rock apart
- Organic acids released speed up chemical weathering
What is mass movement
When material shifts/ moves down a slope/ surface
Sliding (mass movement)
Large chunks of rock slide down the slope QUICKLY without warning
Slumping (mass movement)
(Clay cliffs)
Clay becomes saturated, during heavy rainfall and OOZES down towards the sea
4 Processes of erosion
- Hydraulic action
- Abrasion
- Attrition
- Solution
Hydraulic action
- Water is force into cracks in the rock
- Compresses air
- Wave retreats -> air blasts out
- Rock breaks apart
Abrasion
- Eroded particles in the water SCRAPE and RUB against the rock, removing small pieces
Attrition
- Sediment collides with each other and breaks into smaller pieces.
- Their edges get rounded off
Solution
- Weak carbonic acid in seawater dissolves material from the rock, like chalk and limestone
Which waves carry erosive power
DESTRUCTIVE waves
Formation of a wave cut notch/platform
- Sea erodes the base of a cliff
- The notch increases in size -> cliff collapses, rock above is unsupported
- Collapsed material is carried by backwash
- New wave cut notch starts to form
- Repeated collapsing results in the cliff retreating