Coasts - Weathering and Mass Movement. Flashcards
Mass movement meaning
-the downhill movement of sediment that moves because of gravity.
Rockfall
Bits of rock fall off the cliff face,
-usually due to freeze-thaw weathering.
Mudflow
Saturated soil (soil filled with water) flows down a slope.
Landslide
Large blocks of rock slide downhill.
Rotational slip
Saturated soil slumps down a curved surface.
Coastal slumping
- a cliff is made up of porous material
- cracks appear in the cliff if there has been a long period of dry weather
- Rainwater infiltrates the cliff
- turns the cliff into saturated soil - making it heavy
- puts pressure on the rocks beneath
- a curved slip pane develops
- cliff gives way and slumps (slides) along the slip pane
slip pane
- Rainwater infiltrates the cliff
- due to the porous material
- This then creates a slip plane
Freeze-thaw weathering
- water enters cracks in the rock
- temp decreases = water freezes
- cracks expand
- during the day, temp increases = ice melts
- water seeps deeper into teh cliff
- process repeats itself
- bigger/deeper cracks appear
Biological weathering
- plants grow + roots grow in the cracks of the rock
- expanding cracks
- pieces of rock break off
Chemical weathering
- rainwater/seawater are weak acids
- overtime, coastline becomes dissolved by the acid
- due to the cliff being made up of chalk/limestone
chemical weathering refers to
disintegration of rocks through chemical reactions
salt weathering
-weakens rock structure = cracks
- seawater evaporates and remaining salt crystallises
- salt spray from sea enters cracks
-causes a dramatic increase in volume
mechanical weathering
rocks disintegrated into smaller and smaller pieces
eg of mechanical weathering
freeze thaw weathering
salt weathering
eg chemical weathering
carbonation
hydrolisis
oxidation
