Glaciated Landscapes Unit 2 Flashcards
What is the cryosphere?
The parts of the Earth’s crust and atmosphere that are below 0˚C for at least part of each year.
What are the two main categories of ice masses?
- Constrained ice masses
- Unconstrained ice masses
What factors control the morphology of ice masses?
- Climate
- Topography
Define unconstrained ice masses.
Ice masses with a morphology and flow pattern that is largely independent of underlying topography.
Define constrained ice masses.
Ice masses with a morphology and flow pattern that is strongly dependent on underlying topography.
What is the primary distinction between cold-based and warm-based glaciers?
Cold-based glaciers are frozen to the bedrock, while warm-based glaciers have liquid water at their base.
Where are cold-based glaciers typically found?
High latitude locations such as Antarctica and Greenland.
What is pressure melting?
Melting of ice at temperatures below 0˚C due to the pressure from the weight of overlying glacial ice.
What is regelation?
The process where ice melts under pressure and refreezes when the pressure is reduced.
What are the two specific processes of basal sliding?
- Enhanced Basal Creep
- Regelation Slip
What is internal deformation in glaciers?
The response of individual grains of ice within the glacier to the overlying pressure.
What are the two mechanisms that cause internal deformation?
- Intergranular Flow
- Laminar Flow
What is the typical range of glacial movement in meters per year?
3 to 300 meters per year.
What is the primary difference in movement between warm-based and cold-based glaciers?
Warm-based glaciers generally have a greater overall velocity of ice movement than cold-based glaciers.
What happens during a glacial surge?
A glacier’s snout advances up to 1000 times faster than normal due to changes in sub-glacial meltwater flow.
Fill in the blank: The __________ builds up underneath the glaciers during a phase of normal glacier flow.
WATER
Fill in the blank: The subglacial __________ channels are closed during winter, increasing ice accumulation.
MELTWATER
True or False: Polar glaciers can move by basal sliding.
False
What is the pressure melting point?
The temperature below 0˚C at which ice can melt due to the pressure of overlying glacier ice.
What is an ice sheet?
Complete submergence of regional topography, forming a gently sloping dome of ice several kilometres thick in the center.
Approximately 50000km2
Unconstrained
Example: Antarctic Ice Sheet
What is an ice cap?
A smaller version of an ice sheet that occupies upland areas.
Less than 50000km2
Unconstrained
Example: Austfonna Ice Cap in Svalbard Archipelago in Norway
What is a valley glacier?
A glacier confined between valley walls, terminating in a narrow tongue, forms from ice caps/sheets or cirques. May terminate in the sea as a tide water glacier.
3-1500km2
Constrained by valley walls
Example: The Fraser Glacier - Alaska
What is a piedmont glacier?
A valley glacier that extends beyond the end of a mountain valley into a flatter area and spreads out as a fan.
3-1000km2
Constrained
Example: Malaspina Glacier in SE Alaska, USA
What is the typical size range of an ice field?
10 – 10,000 km².
What is the typical size range of a cirque glacier?
0.5 – 8 km².
Fill in the blank: Warm based glaciers are found outside of the polar region, usually in high altitude areas where the temperature fluctuates __________.
above and below melting point
What is the effect of slope angle on glacier movement?
Increased slope angle accelerates ice movement due to higher forces of gravity.
What is the role of geothermal energy in warm-based glaciers?
It contributes to melting at the base of the glacier.
Define ‘crevasses’.
Fractures in the ice that occur when ice moves on a steep slope and cannot deform quickly enough.
What is the average temperature range at the surface of cold-based glaciers?
-20˚C to -30˚C.
What is an ice field?
Ice covering an upland area but not thick enough to bury the topography. Many do not extend beyond the highland source.
10-10000km2
Constrained
Example: James Ross Island on the NE Antarctic Peninsula
What is a cirque glacier?
Smaller glacier occupying a hollow o the mountain side- it carved out a corrie or cirque; a small version is known as a niche glacier.
0.5-8km2
Constrained
Example: Eel Glacier on Mount Anderson (Olympic National Park, Washington, USA)
What is the pressure required for the ice to melt in a glacier with pressure melting?
As pressure increases the temperature at which ice melts will fall below 0C at a rate of 1C for every 100Kg/cm2 of pressure.
Eg: if the pressure at the base of a glacier is 400Kg/cm2 then ice with a temp of warmer than -4C will melt
