Sub-aerial Weathering Flashcards
What are the three types of weathering?
Mechanical/ physical
Biological
Chemical
What type of weathering is freeze-thaw?
Physical
What type of weathering is carbonation?
Chemical
What type of weathering is solution?
Chemical
What type of weathering is hydration?
Chemical
What type of weathering is pressure release?
Physical
What type of weathering is hydrolysis?
Chemical
What type of weathering is oxidation?
Chemical
What does physical weathering depend on?
It depends on the nature of the climate.
What is chemical weathering?
This is where chemical processes break down the rocks.
When does chemical weathering occur?
This occurs when rocks are exposed to air and moisture.
What is biological weathering?
This involves processes that lead to the break down of rocks by vegetation and coastal organisms.
What is pressure release?
This is where geomorphological processes remove overlying material from the rock.
What geomorphological processes cause pressure release?
Weathering, mass movement and erosion.
What is freeze-thaw?
This is where water enters cracks in the rocks and then freezes. When water freezes it expands and therefore exerts pressure on the rock. The process repeats causing the crack to widen and then pieces of rock to break off.
What is solution?
This is where water dissolves rocks.
What is oxidation?
This is where oxygen that is dissolved in the water reacts with minerals in the rocks to form oxides and hydroxides which causes the rock to disintegrate.
In what type of rock is oxidation most likely to occur?
Oxidation mainly affects ferrous, iron rich rocks.
What is hydration?
This is where water is added to the rock, causing it to expand by creating stress.
What can hydration cause?
It can cause rocks to disintegrate or cracks and joints to widen.
What is hydrolysis?
This is where mildly acidic water reacts or combines with minerals in the rock to create clays and dissolvable salts which degrades the rock. The clays and salts are likely to be weaker than the parent rock.
What is carbonation?
This occurs when CO2 is dissolved in rainwater to create a weak carbonic acid which reacts with calcium carbonate rocks to make calcium bicarbonate which dissolves easily in water.
Give two examples of calcium carbonate rocks.
Limestone an chalk.
Where is carbonation most effective?
It is mot effective in areas with cool temperatures.
What is acid rain?
This is where slightly acidic rainwater caused when water mixes with certain compounds, dissolves rock.
What type of weathering is acid rain?
Chemical
What does the nature of mass movement depend on?
It depends on the level of cohesion within the sediment.
The height and angle of the slope.
Grain size within the sediment.
Temperature and level of saturation.
What can mass movement either be?
It can either be rapid sudden failures of the slope or the effect of a process that has been ongoing for sometime.
What are rockfalls?
These occur from cliffs that have been undercut by the sea or on slopes affected by mechanical weathering.
What are landslides?
This occurs on cliffs made from soft rock or deposited material which slips as a result of a failure in the rock when lubricated.
What are landslides usually caused by?
Heavy rainfall.
What is rotational slip or slumping?
Excessive lubrication causes whole sections of the cliff face to move downwards with a concave side plane which creates a rotational movement.
What causes rotational slip or slumping?
This occurs when softer material overlies harder, more resistant material.
What are mudflows?
This occurs when heavy rain causes large quantities of material to flow downhill.
What causes mudflows?
When soil becomes saturated, excess water cannot percolate deeper into the ground, the surface layers become very fluid and flow downhill.
What are mudflows referred to as on gentle slopes?
Solifluction
What is soil creep?
This is the very slow but continuous movement of individual soil particles downwards.
Is runoff a type of mass movement?
No
What is run-off?
This is water that runs across the land surface. Sometimes it can take large quantities of load with it.
