Sub-aerial processes Flashcards
What are Sub-aerial processes?
Sub-aerial processes occur on land and include weathering and mass movement speeding up coastal recession by destabilising cliffs
What is weathering?
The gradual breakdown of rock in situ
What are the 3 types of weathering?
- Mechanical weathering
- Biological weathering
- Chemical weathering
What is the process of freeze-thaw weathering?
- Rainwater collects in a crack in the cliff
- The temperature drops below 0 degrees and the water freezes and expands making the crack bigger
- Eventually after repeated freezing and thawing the rock breaks off
What are two examples of biological weathering?
Root wedging and puffins making burrows in soft cliffs
What is mass movement?
The downslope movement of large bodies of rock or soil that varies in speed from sudden to soil creep which can be less than 1cm/y
Where is mass movement common?
It is common at the UK coast when weathered cliffs are undercut by waves and rainwater which adds weight to the rock or soil and lubricates the slide planes
Where do you see terracettes?
In an area of soil creep and solifluction
What does slumping create?
A rotational scar and terraced cliff profile
Where do slumps often occur?
They are common where softer materials overlie more resistant rock on moderate to steep slopes often in saturated conditions
What is the process of salt weathering?
Evaporating salt water leaves a residue of salt crystals and these grow over time and exert stress on cracks in the rock
What is pressure release weathering?
As the weight of overlying rocks is removed by erosion, underlying rocks expand and fracture near the new ground surface
What is solution weathering?
Rainwater absorbs carbon dioxide as it falls through the air forming a weak carbonic acid which corrodes the alkaline calcium carbonate found in some rocks
