1.c Types of Glaciers + movement Flashcards
What are the two different types of glaciers?
Temperate ( warm based)
Polar (cold based)
what is the pressure melting point?
The temperature at which the ice is on the verge of melting
Temperature profile/rate of accumulation / ablation of TEMPERATE
T = 0 degrees base
-10 degrees surface
Accumulation =greater in winter
Ablation = rapid in summer
Temperature profile/rate of accumulation / ablation of polar
T = all times well below 0 degrees
accumulation = rates are low
Ablation = rates are low
PMP of temperate glaciers
At or above PMP due to warmer atmospheric pressure so melts at base.
PMP of Polar glaciers
Below PMP so no melting as ice stays cold and stays frozen to bedrock all year
Location of temperate and polar glaciers
Temperate = higher altitudes
Polar - higher latitudes
What is the average rate of ice movement per year?
3m-300m per annum
What are the 6 factors that impact how a glacier moves?
1- gravity
2- gradient - steeper = faster
3- thickness of ice
4- internal temperature
5- glacial budget
6- bedrock geology
What are the two main types of glacial movement ?
Internal deformation and Basal sliding
What movement is for temperate and polar glaciers?
Polar = Internal deformation
Temperate = basal sliding
What is Basal Sliding?
sliding of a temperate glacier over bedrock due to more meltwater lubricating easier movement
What is the basal slip in basal sliding ?
lubricating effect of meltwater,making easier to move
What is the enhanced basal creep in basal sliding ?
obstacle in glacier path increases pressure → begins to behave like a plastic flowing around an obstacle.
What is the regelation flow ?
An obstacle in the way causing the ice to melt to get over the obstacle then refreezes → the latent heat released by refreezing conducts back and leads to this melting earlier.
What is slippage?
circular motion that can cause ice to move away from the back wall of a hollow
What is creep?
slow downward movement of lose rock and soil down a slope
what is bed deformation?
movement of soft sediment beneath a glacier.
What is internal deformation?
In very cold climates cold based glaciers are frozen to bedrock so no friction and no increase in pressure
As a result, Ice crystals in the ice move in direction of the movement
They slide past each other leading to crevasses.
In internal deformation what parts of the glacier moves faster?
The surface of the glacier moves faster than the base. → base frozen to bedrock
The middle of the glacier moves faster than the sides. → as attached on each side / middle furthest away than anything it’s frozen too.
What is inter granular flow ?
individual ice crystals move relative to eachother
What is Laminar flow?
individual ice crystals move along layers within the glacier.
What is a serac?
tower of ice which forms in the middle of a crevasse
What is a crevasse ?
A deep wedge in the glacial ice
