2a.Geomorphic Processes Flashcards
1
Q
Weathering - physical
A
- Break down of large rock mainly due to this
- Produce similar smaller fragments of the same rock
- allows for further weathering to take place
- Freeze thaw: Water expands nearly 10% when freezes, exerts pressure on rock causing the crack to largen or even break
- Frost shattering: Water trapped in pores freezes and expands, disintegrating rock
- Pressure release
2
Q
Pressure release
A
- Weight of ice in glacier is lost due to melting, rock expands and fractures parallel to surface
- Exposes sub surface rocks
3
Q
Weathering - chemical
A
- Reduces rock to chemical constituents
- Rate is faster when temp is high
- Different chemical composition of rocks
- Oxidation: Some minerals in rock react with oxygen in air or water
- Carbonation: Co2 dissolves in rain water to produce acid rain, reacts with rocks
- Solution
- Hydrolysis
- Hydration
4
Q
Solution
A
- Some salts are soluble in water
- Minerals like iron dissolves in very acidic water
5
Q
Hydrolysis
A
- Chemical reaction between rock minerals and water
- Silicates combine with water to produce secondary minerals eg: clay
6
Q
Hydration
A
- Water added to rock minerals create new ones of a larger volume
- Some minerals also expand
7
Q
Weathering - Biological
A
-Consist of physical actions
- Tree roots
- Organic acids
8
Q
Tree roots
A
- Grow into cracks in rocks and exert outwards pressure
- Trees also exert leverage on rock / soil when they fall
9
Q
Mass movement
A
-Forces acting on slope exceed forces keeping mass on slope
- Rock fall
- Slides
10
Q
Rock fall
A
- Slopes at 40 degrees or more
- Rocks become detached via physical weathering and fall
- Transport removes rock
11
Q
Slides
A
- Linear with movement along straight line slip plane
- Rotational with movement along curved slip plane (slumps)
