What is glacial system?
A dynamic open system with inputs, outputs, stores, and transfers of energy and material
What are the main inputs to a glacial system? (Accumulation)
Snowfall, avalanches, wind-blown snow, and solar energy
What are the outputs from a glacial system? (Ablation)
Meltwater, evaporation, sublimation, and calving
What are the stores in a glacial system?
Ice, snow, meltwater, debris
What are the transfers in a glacial system?
Ice movement, meltwater flow, debris transport
What is the glacial mass balance?
The balance between accumulation (input) and ablation (output) over a year
What is the equilibrium line?
The boundary between the accumulation and ablation zones
How do glaciers move?
-Internal Deformation
-Basal Sliding
-Shear stress
-Regelation Creep
International deformation
The weight of the glacier causes crystals to deform so the glacier moves slowly downslope or individual layers of the glacier moves forward
Basal Sliding
Water lubricates the base of the ice, caused by pressure melting when the glacier advances over rocks
Downhill movement increases temperature which can create a feedback
Shear stress
Glaciers accumulate mass in their upper portions, which creates pressure due to the “wedge shape” created
Regelation Creep
Glaciers can melt and freeze depending on pressure build up and surface temperature.
This slowly moves the glacier down hill
What is extensional flow?
Ice stretches and speeds up on steep slopes, causing crevasses
What is compressional flow?
Ice slows down on gentler slopes, thickens, and compresses
Factors of movement
-Ice thickness
-Precipitation levels
-Rates of ablation
-Bedrock permeability
-Ice and slope gradient
-Ice temperature
Polar vs Temperate
Polar- almost only internal deformation, so slow
Temperate- more basal sliding, so faster
What is glacial debris entrainment?
Material incorporated into or onto the glacier
Where in the glacier
Supraglacial- On top of the glacier
Englacial- Worked its way into the glacier
Subglacial- Carried below the ice
Where processes occur
-Subglacial
-Marginal
-Proglacial
-Fluvioglacial
-Periglacial
Subglacial
-Below the glacier or ice sheet -Erosion is common here
-Can form striations, roche moutonnée and eskers
Marginal
-At the sides or end of the glacier
-Weathering and deposition occur here
-Create moraines
Proglacial
-In front of the glacier or ice sheet
-Fluvioglacial processes occur here
-Creates outwash plains & meltwater channels
Periglacial
-At the edges of glaciers, often extensive areas
-Processes associated with snow and melting such as blockfields and pingos.
