Geomorphic processes key terms (2) Flashcards
What is weathering?
The breakdown of rocks by chemical, biological and physical processes to form new landforms.
What is chemical weathering?
Reactions occur within a rock causing decay
- oxidation
- carbonation
- solution
What are the 3 types of chemical weathering?
- carbonation (rainwater reacts with CO2 forming weak acids which reacts with calcium carbonate)
- oxidation (minerals react with oxygen = compounds break down)
- solution (minerals dissolved in water)
What is physical weathering?
Process of smaller rock fragments being created without chemical changes.
What is freeze thaw weathering?
- Physical weathering process
- Water entering cracks, freezing then expanding by 10%.
- Increased pressure splits the rock into fragments.
What is frost shattering?
- Rocks disintegrate
- Water in porous geology expands
What is biological weathering?
The process of compound breakdown because of organisms.
eg. tree roots bringing material to surface, decomposition
What is mass movement?
- A fast downslope movement under gravity.
- Rock falls, slide.
- More inputs lead to greater resultant force therefore more movement.
What is ‘slide’ mass movement?
- The movement of rocks, ice along a curved slip plane.
- Usually due to plucking, freeze thaw detaching rocks from back wall of valley.
- Steepen the valley sides.
- Material falls under gravity.
What is plucking?
- Meltwater into cracks in valley sides or floor
- Freezes and attaches to glacier = glacier moves and carries rocks with it.
- More common in warm based because pressure melting point is reached.
What is abrasion?
- Friction based erosion leading to a sandpaper effect.
- More material carried = more abrasion
- Rocks carried sub or en-glacially have largest abrasion force on valley.
- Debris in the ice is broken down into rock flour.
What is nivation?
- A mixture of weathering processes that form a nivation hollow
- Freeze thaw, chemical weathering, solifluction
- Beginning of a corrie.
What does supra glacial mean?
On top of the glacier
What does en-glacial mean?
In the glacier
What does sub-glacial mean?
At the base of the glacier
Interacts most with valley floor.
What is boulder clay aka till?
Material deposited by ice glaciers.
Unsorted, unstratified, angular (no attrition)
What is drift?
All material deposited by a glacier
What are the two types of drift?
Outwash and till.
What is outwash?
Deposit from glacio-fluvial streams and other water bodies.
Sorted, rounded (attrition), stratified
What are the two types of till deposition?
Lodgement (downward pressure causing ice to deposit debris).
Ablation (from melting ice during warm periods)
