Glaciers- Overview Flashcards
Mass Balance
This is the accumulation of snow fall measured against melting, evaporation or breakaway.
When do glaciers form?
When accumulation exceeds ablation.
What is required for formation?
Specific climate conditions
What are the two zones of the glacier?
Ablation and Accumulation, seperated by an equilibirum line.
What is the pathway of meltwater?
Deposits into sea, carving structures, depositing sands, silts and gravles.
What are the ways glacial movement occurs?
Sliding, Ice Deformation and deformation of the glacial bed.
What is rate of movement of a glacier dependent on?
Gravitational Forces
Resistance such as a drag of the bed
What are examples of indications of glacial presence?
Corries, troughs, drumlins and moraines.
What are the two major types of glaciers?
Ice Sheets
Ice Caps
Ice Sheets
These are marked as ice domes exceeding 50,000km^2
Ice Caps
High-latitude regions of a planet covered in ice.
Ice Dome
Where mass is radially distributed outwards acting as dispsersal centres
What are the two types of stream flow from a glacier?
Outlet Glaciers
Ice Streams
Features of Outlet glaciers and Ice Streams?
Both rapidly moving, chanelled ice radiating from the interiors of the ice sheets.
Outlet Glaciers
These occupy troughs of valleys being valley glaciers draining an inland sheet/cap flowing through a gap in peripheral mountians.
Ice Streams
These occur within ice sheets responsible for discharge of most the ice and sediment within, flanked by slowly moving ice.
What are the types of glacier based on topography?
Valley Glaciers
Transection Glaciers
Cirque Glaciers
Piedmont
Niche
How do valley glaciers form?
Ice discharge from cirques or ice fields in a deep bedrock valley.
Transection Glaciers
These are large networks of interconnected valley glaciers flowing in different directions
How much of the Earth is covered in glacier?
16million km^2, 13.5 in Antarcitca and 1.74 in Greenland
What does glacier distribution vary with?
Altitude, latitude, distance from precipitaiton and temperature changes
Why do higher altitudes have more glaciers?
Temperatures decrease with air density
Equilibirum Line Altitude
This is the region on the glacier where accumulation equals ablation.
Why is slope aspect important in glacial formation?
Differenetial relief of solar radiation and precipitaiton.
What is an example of a structure without capacity to accumulate snow?
A narrow summit with steep sides.
How much ice cover in peak of quarternary glaciations?
30%
What factors influence glaciation PERIODS?
Gradual increase in solar luminosity(4BYA was 75% present value
Faint-Sun Paradox
The sun was younger with less luminosity yet the climate as warm as it is today
Why has the planet remained relatively stable in temperatures?
GHG regulation by tectonic movement and silicate weathering
Effects of silicates on temperature?
Burial, where upwelling results in release by volcanic outgassing
How does topography regualte climate?
Mountain chains and continents influence ocean and atmospheric circulation
What is the milankovitch cycle dependent on?
Eccentricity
Obliquity
Precession
Eccentricity
This is deviation of Earths orbital path from the shape of a circle on 100,000 year cycles.
Obliquity
This is the planets plane of orbit spinning on an axis on the angle between orbital plane and spin axis(41,000 year cycles)
Precession
This is the change in orientation of rotational axis of a rotating body(23,000 year cycles)
