Glacier Flashcards
How much land surface of the earth do glaciers currently comprise?
10% of land surface (15 million km2)
How much would the sea level rise if all ice melted?
80 m
How do Glaciers form?
-Accumulation of snow surviving summer
-Ablation (Such as sublimation, fusion or melting, and evaporation) 50 to 70 m of snow accumulation needed for transformation.
Ice sheets
- Cover large areas of land or sea (e.g., Greenland and Antarctica)
- Ice sheets are continental-scale masses of ice that rest on land.
- The shape of an ice sheet is a dome that slopes downwards toward its edges, where the interior ice may be thousands of meters thick and the ice around the edges tens of meters thick.
-Ice sheets are dynamic, flowing from the interior toward the ice sheet’s edge like honey poured onto a mound on a flat surface.
-The ice sheets serve as large reservoirs of frozen fresh water. This means that over time, when ice sheets gain mass, they contribute to a fall in global mean sea level, and when they lose mass, they contribute to a rise in global mean sea level.
-An ice sheet gains mass when snow falls on it, especially at high elevations within its interior. An ice sheet loses mass, however, due to various processes.
Ice Shelves
-Arctic ice shelves (primarily located along the north coast of Ellesmere Island in the Canadian High Arctic) form through the seaward extension of one or more glaciers and/or through the formation of multiyear sea ice.
-The floating ice mass thickens further through snow accumulating on the surface and by accretion at the base of the ice shelf.
-An ice island forms when the margin of the ice shelf detaches and becomes free floating in a process called calving.
Continental Ice Sheets
-Continental ice sheets play a significant role in climate change conditions because of their huge size.
-Melting and disintegration decreases the ice albedo (ability to reflect light and heat) increasing the global temperature and changing the balance and pattern of the Earth’s radiation.
-Melting of the Arctic ice sheet would change the North Atlantic and Arctic oceans currents, altering the ocean circulation systems that transfer heat around the planet.
Alpine (Mountain)
Confined to mountain valleys
> Ice cap
> Cirque glacier
> Valley glacier
> Fjord glacier
> Piedmont glacier
How is glacial flow or movement achieved?
Internal plastic flow and basal sliding
Internal plastic flow
glaciers flow and deform in a similar manner to ductilely
deforming rocks. The processes involve slip and deformation of the ice crystal
structure at the microscopic‐scale.
Basal Sliding
Many glaciers have abundant melt water at their base. This may be melt water that has flown through the glacier to the base, or it may be pressure‐ induced melt water at the base of the glacier. In either case the water lubricates the base of the glacier allowing it to slide over the underlying rocks and gravel.
What are striations?
scratches or grooves that are parallel to the movement direction of the glacier
What are eskers?
long, narrow, winding ridges of sand and gravel
What are kettles?
hollows or undrained depressions that are often occupied by ponds and lakes
What are kames?
small hills of sand and gravel dumped near the edge of the ice
What is a Moraine?
a deposit of rocky, sandy or clayey material carried and deposited by the glacier
