3.1.4.3 Geomorphological Processes 2 Flashcards
Define erosion
The wearing away of the lands surface; including the breakdown of rock + its removal by wind,water and ice
Define weathering
The breakdown of rocks in situ, producing finer particles that can be moved by erosion
What’s is situ
In original location without being moved
What does weathering produce used by glaciers for erosion
Debris
What’s the main type of weathering cold environments
Most important process
Physical weathering Frost shattering (freeze thaw action)
3 ways material is transported in a glacier
Supraglacial (surface) debris
Englacial (inside) debris
Subglacial (under) debris -> rolled and carried on bed
What’s moraine
4 types
Material left behind once a glacier melts, creating a landform
Lateral moraine (sides) Medial moraine Terminal moraine (at snout) Englacial moraine (in)
What makes up the medial moraine
2 lateral moraine tributaries meeting
Where does glacial erosion occur
Ice-rock interface (meeting point)
What type of ice has more of an erosive effect (2)
Ice moving
Ice carrying loose debris
4 processes of glacial erosion
Abrasion
Plucking
Rotational Movement
Extending - compressing flow
What’s abrasion also known as
The sandpaper effect
When does plucking occur
During regelation slip when ice freezes
Where does maximum erosion occur (3)
Where temps fluctuate around 0* allowing freeze-thaw
In areas of jointed rocks
Where 2 tributary glaciers join/valley narrows giving increased ice depth
In steep mountainous regions where velocity is greatest (temperate)
What’s abrasion
Sandpaper effect as ice grinds over + scours a landscape
What will form from erosion on bedrock
Striations
What happens to the large rocks under ice over time due to erosion
They get pulverised by the weight and form fine rock flour
What does fine rock flour do to the bedrock
Smooth + polish it
Describe plucking
When meltwater freezes part of the underlying bedrock to the glaciers base and any loosened fragments will be ‘plucked’ away as the glacier slips forward
Where is plucking particularly common
Where a reduction in pressure under ice has led to regelation (refreezing of meltwater in regelation slip)
Eg of an extending flow crevasse
Bergschrund crevasse
Describe frost shattering (freeze thaw)
Water enters joints and freezes during cold nights
Ice occupies around 9% more volume than water + exerts pressure within the joint. This alternating freeze-thaw process slowly widens the joints
bits to break off from the main rock body
