Weathering and mass movement Flashcards
What is weathering?
The breaking down of rock in situ caused by weather, animals, and plants.
Weathering processes significantly impact coastlines.
What causes biological weathering?
Animals burrowing into cliffs and plant roots expanding cracks.
Biological weathering weakens rocks.
What is chemical weathering?
A process caused by rainfall that creates a chemical reaction with rocks.
It involves reactions like carbonation.
Define carbonation in the context of weathering.
Rainfall containing carbonic acid reacts with calcium carbonate in limestone, forming calcium bicarbonate.
Calcium bicarbonate is soluble and gets dissolved.
What is mechanical (physical) weathering?
Weathering caused by extremes of temperature or changes in moisture leading to rock disintegration.
It does not involve chemical changes.
What is freeze-thaw weathering?
Water enters cracks in rocks, freezes at night, expands, and puts pressure on the rock, causing cracks to grow.
Repetition leads to rock breaking away.
What is mass movement?
The downward movement of rock, soil, or mud due to gravity, often exacerbated by weathering processes.
Heavy rainfall usually triggers mass movement.
What are landslides?
Downhill movement of large volumes of rock, soil, and mud, often triggered by heavy rainfall.
Landslides can occur on steep hillsides and cliff faces.
What occurs during a rock slide?
Large amounts of rock slide down a cliff as a block, ending up as a pile at the cliff base.
This movement can be rapid and destructive.
What are mudflows?
Wet and rapid slides of saturated soil on steep slopes lacking vegetation.
The saturated soil spreads over a large area at the cliff base.
What are rock falls?
Fragments of rock break away from a cliff face, often due to freeze-thaw weathering.
Rock fall material collects at the bottom, forming a fan-shaped scree slope.
What is slumping?
Movement of material down a concave cliff face, often called rotational slip.
The material rotates backwards into the cliff face as it slips down.
