Glacier movement Flashcards
What is a glacier system
It has interrelated components/ characteristics such as inputs/outputs
Define ablation
The output of snow/ice from a glacier by melting, sublimation or evaporation
Inputs of a glacier
Snow, ice
Precipitation, avalanches, wind deposition
Outputs of glacier
Melting, iceberg calving, sublimation, evaporation
What is the equilibrium line
The boundary between the two zones (accumulation and ablation)
How is glacier mass calculated
Year’s total accumulation - total ablation =Glacier mass balance
Factors that increase glacier movement
Ice temp
Pressure melting point is reached
Amount of meltwater
Types of movement for a temperate glacier x4
Basal slip
Creep and regelation
Extending and compressing flow
Surges
Types of movement for a polar glacier
Internal deformation- occurs when weight is ice and gravity cause the ice crystals to deform so glacier moves downhill
Define basal slip
Occurs at base of glacier when PMP is met and meltwater acts as lubricant causing glacier to Slide Over bedrock
Define creep and regelation
Basal slip is enhanced by obstacles
Creep- large obstacle causing increase in pressure. Ice deforms around obstacle
Regelation- smaller obstacle casing melting and more basal slip and re freezes further downslope.
Define extending and compressing flow
Extending flow- steep slopes causes basal slip to increase and the ice will accelerate and become thin
Compressional flow- shallower slopes basal slips slows and ice decelerated and thickens
Define surges
Short lived events where glacier dramatically advances caused by earthquakes or enhanced basal slip due to large amount of meltwater
Factors which accelerate glacier movement x6
Ice thickness- thicker more pressure/movement
Precipitation level- more accumulation/faster movement
Rate of ablation- more meltwater more movement
Bedrock permeability- bedrock permeable able to soak away slowing movement
Ice/slope gradient- steeper angle more movement
Ice temperature- warmer faster
Ñame glacial processes x4
Erosion
Entrainment- rock fragments trapped by basal ice causing them to be dragged
Transport- rock debris transported on ice surface
Deposition- till deposited by glacier ice
