Glacial Systems & Landscapes: Glacial Processes
- Created by: IssyCalderwood
- Created on: 19-12-18 20:17
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- Glacial Processes
- Cold Based Glaciers (CBG)
- Very cold areas - Antarctica
- Very little melting
- Very little movement
- Very little erosion
- Warm Based Glaciers (WBG)
- Milder areas - base is above ice melting point
- Because friction or geothermal heat
- Meltwater = lubricant = lots of downhill movement
- Basal sliding
- Processes
- Rotational flow
- Glaciers = move in arc shape in hollow
- Extensional flow
- Compressio-nal flow
- Low down = ice slow = faster ice pushes down = compression = high pressure = ice fracture in layers = slip forwards
- Head of glacier = strong gravitational force = ice move quickly = more tension = ice fracture in layers = layers slip downwards
- Compressio-nal flow
- Internal deformation
- Ice crystals shift past each other = ice bends and warps like liquid
- Main movement for CBG
- Ice crystals shift past each other = ice bends and warps like liquid
- Basic
- Protruding rock = more pressure = more melting
- Ice will melt below melting point
- Less pressure downstream obstruction= meltwater refreezes
- Flow = fast around obstruction / slow downstream
- Protruding rock = more pressure = more melting
- Rotational flow
- Processes
- Basal sliding
- Lots of erosion
- Milder areas - base is above ice melting point
- Nivation and Frost Action Weathering
- Frost action
- Freeze thaw where moisture and temp fluctuates around freezing
- Water enters cracks in cliff faces
- Temp drops below freezing and water freezes and expands
- Repetition weakens rocks and pieces fall off
- Temp drops below freezing and water freezes and expands
- Water enters cracks in cliff faces
- Freeze thaw where moisture and temp fluctuates around freezing
- Nivation
- Temp fluctuates around freezing (lots of freezing and thawing of ice)
- Ice freezes = expands = frost shattering = rocks break off
- Snow melts carrying away debris
- Waterlogged, eroded slopes collapse
- Snow melts carrying away debris
- Eventually hollow = deeper and wider
- Beginning of a corrie
- Ice freezes = expands = frost shattering = rocks break off
- Temp fluctuates around freezing (lots of freezing and thawing of ice)
- Frost action
- Plucking and Abrasion
- Plucking
- Ice thaw and refreeze around rocks
- Glacier moves forward plucks rock away
- Ice thaw and refreeze around rocks
- Abrasion
- Debris carried by glacier = scrape material off valley floor and walls
- Plucking
- Debris Transport
- Subglacial = moved along the base
- Englacial = within the body of the glacier
- Supraglacial = on top of the glacier
- Till = unsorted deposited sediment
- Lodgement till = spread by moving glaciers
- Ablation till = dropped as melts
- Cold Based Glaciers (CBG)
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