Glaciers Flashcards
What is the cryosphere?
All frozen water on the earth
What is albedo?
The percentage of light reflected back off the ice
Define normal fluids
They deform instantly when a shear is applied upon them
Define non-newtonian fluids
Their viscosities and rate of deformation decrease as shear stress is increased
What are the two conditions needed for glaciation?
- precipitation
2. Temperatures that will preserve the ice over the summer
What kind of competence do glaciers have?
Very high
A poorly sorted mixture of mud, sand and gravel is called…
diamicton
What is till?
Diamicton lain down from glacier ice, has not been disturbed since.
What is an esker
An elongated ridge of sand and gravel generated by meltwater flowing from to the front of the glacier under pressure and depositing the sediment
True or false: water is the only chemical on earth to occur naturally in all three phases
True
Define permafrost
Ground that is constantly at a temperature below 0 degrees Celsius
When sea ice forms, what two things occur?`
Dense, cold water that plunges to the ocean bottom
Salt is rejected when the ice forms, therefore the ice is primarily fresh.
What is the thickness of sea ice
Never more than several meters
What is another name for normal fluids, and please define them
- Newtonian fluids
2. They deform instantaneously with applied shear, and viscosity increases linearly when shear stress is increased
some fluids are non-newtonian. what does this mean?
Their viscosities decrease as shear stress is increased.
OR
They exhibit shear thickening behaviour, where viscosity increases as shear stress increases
Because ice can behave as both a solid and a fluid, what is ti said to be? (2 things)
- viscoelastic
2. exhibits considerable shear thinning behaviour (shear stress needs to be really high before it flows)
The two main types of glaciers
ice sheets and alpine glaciers
where are the two main ice sheets?
over Antarctica and greenland
What are ice domes?
elevated areas of ice from which ice flows radially.
What is an ice stream?
areas on the extremities of ice sheets, where ice will flow several magnitudes faster than the ice around it.
Define calving
Occurs when an ice stream meets the ocean. It starts to float, thin considerable, form an ice shelf, which then breaks off into icebergs.
What two places allow for the formation of ice sheets and glaciers?
High altitude and latitude
What is firn?
Snow that has survived the summer melt season
Why can glacier formation be equated to metamorphic rock?
Glaciers form by recrystallization of
snow flake crystals, just like a metamorphic rock forms by recrystallization of
an igneous, sedimentary or metamorphic rock precursor.
What is an accumulation zone?
an inner zone of mass gain on an ice sheet
What is an ablation zone?
An outer zone on an ice sheet of mass loss
What is the equilibrium line on an ice sheet?
Where accumulation = ablation
What is meant by positive mass balance?
to get a glacier, and to maintain it, accumulation must exceed ablation
Three mechanisms by which a glacier moves
a) ice deformation,
b) basal sliding, and
c) subsole deformation
Define ice deformation
base of glacier below pressure melting point, so glacier frozen to the ground. Therefore, the only way the glacier moves is by deformation
Define basal sliding
If the base of glacier is above the pressure melting point of ice, movement can occur by all three processes of movement.
