Glacial Processes Flashcards
Contains - Warm and cold glaciers - Glacial processes - Geomorphological processes
What are warm based glaciers?
Typically associated with a temperate environment, e.g., the European Alps
What are cold based glaciers?
Typically associated with polar environments, such as Antarctica or Greenland, where the ice is much colder
How do warm based glaciers move?
Due to the temperate climate there is an increase of meltwater, which acts as a lubricant promoting basal sliding
How do cold based glaciers move?
Cold based glaciers move much less, but when they do, its due to internal deformation
What is internal Deformation?
When the weight of the ice causes deformation of ice crystals
What are the two mechanisms of internal deformation?
Intergranular movement and Intragranular movement
What is intergranular movement?
When individual ice crystals slip and slide over each other. Ice crystals within the glacier tend to orientate themselves in the direction of the ice movement.
What is intragranular movement?
When ice crystals become deformed or fractured due to the intense mass of ice. Gradually, the ice deforms and moves downhill due to gravity
What is extensional flow?
Ice flows faster due to gravitational pull and will become ‘stretched’ and thin
What is compressional flow?
A reduction in gradient will cause glacier to slow down and pile up, becoming thicker and fracture into layers
What is frost shattering?
When rain gets trapped inside rocks, freezes and expands by 9%, exerting stress on the rock
What are some properties of frost-shattered rocks?
Very sharp, angular. Abrasive against other rocks, eroding other rocks.
What is carbonation?
Carbonic acid reacts with calcium carbonate in some rocks, eroding and dissolving parts of the rock over long periods of time,
What are the variations in the rate of ice movement?
A change in gradient. There are two main variations: extensional flow and compressional flow
What are the two main types of glacial erosion?
Abrasion and plucking
What is glacial abrasion?
A sandpapering effect of ice as it grinds over angular, frost-shattered material
What is glacial plucking?
When meltwater freezes bedrock to the base of a glacier. Loosened rock fragments will by plucked away as the glacier slips forward.
What are the main 3 glacial processes?
Glacial erosion, Glacial Transportation and Glacial Deposition
What are the 3 types of Glacial Transportion?
Supraglacial, Englacial and Subglacial
What is abrasion?
Debris carried along by the glacier can scrape material off the valley walls and floor.
What is plucking?
Ice in contact with rock surfaces can thaw slightly then refreeze around rocks protruding from valley sides and floor. When the glacier moves forward it plucks the rocks away.
What is niviation?
Niviation makes hollows deeper by freeze thaw weathering.
- When snow gets into a hollow, it can increase the size of the hollow
- Every time the ice freezes, it expands, so bits at the bottom of the rock are eventually broken off
- Slopes then collapse because they’ve been waterlogged and eroded
