2.5 A+b Flashcards
Explain the similarities in the movement of polar and temperate glaciers (3 points )
Internal deformation
Inter movement when ice crystals slip and slide over each other
Ice crystals become deformed or fractured due to the intense stresses within the ice
Explain the differences in the movement of polar and temperate glaciers
Basal slip - not in polar
Basal slip accounts for 75% of movement
Pmp is reached on temperate
Creep/regelation,surges, extensional and compressional flow all for temperate not polar
How do temperate glaciers move
Move by both slip and internal deformation
How do polar glaciers move ?
Move only by internal deformation
What is basal slippage
This occurs when the base of the glacier is at the pressure melting point, which means that meltwater is present and acts as a lubricant,enabling the glacier to slide more rapidly over the bedrock.
What is enhanced basal creep
Creep a large bedrock obstacle more than a meter causes an increase in pressure. This makes ice plastically deform around the feature ( creep). Smaller obstacles less than a meter will cause pressure melting thus increasing ice movement by basal slip.
What is extensional and compressional flow
Over steep slopes, the rate of basal slip will increase and the ice will accelerate and thin
What is surges in glacial movement
They are triggered by meltwater at the ice rock interface. The subglacial bed deformation is when a glacier moves over unconsolidated rock and the sediment itself can deform under the weight of the glacier moving than the ice
What is the 2 internal deformation ( internal flow ) movements
Ice crystals can fracture along parallel planes and deform downhill due to the intense stresses within the ice also know as intra-granular movement
Ice crystals can also slip and slide over each other also known as inter granular movement
