Cryosphere 2 -Ice Flashcards
Glacial deposition
As glaciers move along the landscape, they erode the underlying bedrock and accumulate material that falls on them.
Where deposition occurs in glacier ablation areas
at the base and margins of the glacier
Ablation
below the equilibrium line in a glaceir
Till
Poorly sorted sediment left behind by glaciers.
If till is reworked by meltwater beyond the terminus of a glacier, it can be redeposited by
outwash
Moraines
Ridged accumulations of till that form as glacier advances and retreats
Types of moraines
Lateral, medial, and end moraines
Lateral Moraines
Form at the sides of the glacier (types of end moraines)
Medial moraines
Middle moraines forming when two glaciers meet
Terminal moraines
End moraines that show the extent of the glacier before it recedes
Drumlins
elongated and asymmetrical hills that form near the terminus of glaciers by the action of glacial ice on underlying unconsolidated sediments.
The ice flow direction on a drumlin is from the ___ side toward the ___ side of the drumlin.
steep to shallow
Eskers
Ridges of well sorted sand and gravel formed from rivers flowing beneath glacial ice
Kettles
closed basins formed by the melting away of a mass (block) of underlying glacial ice
Kames
piles of sand and gravel that were accumulated in streams and lakes on top of glacial ice, and is deposited on the land surface when the glacier retreats
Proglacial lakes
lakes formed on the top of the ice sheet and at the margin while the ice age was ending
Permafrost
a permanently frozen ground that contains ice that froze during past glaciations
Permafrost is thickest in:
where they were exposed to long periods of colder air temperatures
How permafrost is a carbon sink:
Prevents carbon from being degraded by microbes that would form greenhouse gases
Active layer of permafrost
A layer on top of permafrost that melts every summer
Pattered ground
Cyclical freezing and thawing cycles each year lead to the formation of patterned ground, and to frost heaving called pingos.
Pingos
small hills formed through frost heaving
Sea ice forms when
air temperature falls below the freezing point of seawater (-2 degrees)
Frazil ice
Small needles of frozen ice that initially form as sea water freezes.
Formation of frazil ice into ice sheets
- small needles of ice form as sea ice freezes
- frazil ice freezes together to form ice sheets
- subsequent freezing at the base adds thickness
Sea ice can be __ or ___.
annual or perennial (lasts several years)
Arctic sea ice is highly sensitive to ____.
climate
Sea ice typically moves ____ a day
several km
Leads
When ice cracks forming leads to open water. When leads freeze, they form mosaic patterns.
Pressure ridges
produced by the convergence of ice masses
How sea ice drives ocean circulation
- sea ice freezes leaving salt which makes the ocean more saline (concentrated)
- This water is colder and denser making it sink (flow downward)
How sea ice effects climate
- isolating ocean water from the atmosphere which prevents heat exchange
- high albedo causing it to reflect light and heat
- it contributes to the temperature gradient between the poles and equator driving atmospheric circulation (wind)
