Processes of glacial transport - Glacial debris transportation Flashcards
How much rock debris can glaciers transport and how far are they able to transport it?
Evidence suggests that glaciers and ice sheets are capable of transporting large amounts of rock debris over considerable distances as throughputs of the glacial system.
How many different positions is rock material that is eroded by a glacier, or weathered debris that has fallen onto a glacier transported?
Rock material eroded by a glacier, or weathered debris that has fallen onto a glacier is transported in three different positions.
Describe the first position which eroded rock material or weathered debris that has fallen onto the glacier is transported?
- At the surface or supraglacial zone as subglacial debris
Rocks frequently fall onto the surface of the ice from the valley sides and are transported on the ice surface.
Is supraglacial debris associated more with with valley glaciers or ice sheets?
Supraglacial debris is associated more with valley glaciers than with ice sheets, as rock surfaces are exposed along the sides of valley glaciers, whereas most rock surfaces are beneath the ice surface of ice sheets.
Supraglacial debris can occur in which form?
Supraglacial debris can occur in bands tens of meters in size as lateral or medial moraine.
What is the second position which eroded rock material or weathered debris that has fallen onto the glacier is transported?
- Within the glacier or englacial zone as englacial debris.
How does rock debris often find its way into the ice?
Rock debris often finds its way into the ice via crevasses.
What is the third position which eroded rock material or weathered debris that has fallen onto the glacier is transported?
- At the base or subglacial zone of the glacier as subglacial or basal debris.
What happens to debris fragments once they work their way under the ice?
Debris fragments work their way under the ice where the fragments themselves become shattered and pulverised by the weight of the ice, turning them into tiny pieces.
How are large boulders transported by the glacier?
Large boulders may be dragged along the glacier base by traction.
Is rock debris able to move between transportation positions?
Rock debris is able to move between transportation positions.
Give an example of how rock debris can move between transportation positions?
Supraglacial debris may once have been englacial material. It is brought to a supraglacial position through lowering of the ice surface as the glacier ablates, revealing material previously stored in the ice.
Subglacial material may be brought to an englacial position by movement along shear planes.
What can be inferred by studying the debris left behind after glacial recession?
By studying the debris left behind after glacial recession, it is possible to determine where it came from and how it was transported.
How does debris left behind after glacial recession differ based upon how it was transported?
If carried supraglacially or englacially, the debris will remain largely unaltered. Subglacial rock is altered significantly by crushing and grinding at the ice-rock interface.
In spatial terms, where is transported rock debris more concentrated?
In spatial terms, transported rock debris is more concentrated in the ablation zone relative to the accumulation zone.
