GL - Glacial Modification of Terrain Flashcards
Define:
Glacier?
Extended mass of ice formed from snow falling and accumulating over the years
Define:
Till?
Glacial ‘Alluvium’
Big pile of rocks and debris
Unsorted
Define:
Glacial Erratics?
Big boulders or pieces of rocks that is deposited due to glacial retreat
Explain:
Alpine Glaciers?
Examples?
Glaciers that are found at high Altitude
- Smaller than ice sheets
- Flow downhill through valleys following topography of the landscape
- Under influence of gravity due to unveven terrain
- Highly senstive to changes in temperature and precipitation
-
French Alps, Columbia Glacier (Alaska), Mt. Kilimanjaro Glacier
Explain:
Continental Ice Sheets?
Examples?
Glaciers that are found at extreme Latitudes (Polar Regions)
- Huge in size
- Flow outward from centers and movement controlled by size and weight
- Regulates global sea levels
Antartica, Greenland
Explain:
Importance of glaciers?
- Sea level changes
- Shape our landscape
- Create Major landforms and lakes (Great Lakes)
- Cause crustal movements (Icostasy)
- Contribute to earht’s largest source of fresh water (~75%)
Define:
Moraine?
Example?
A pile of material that is deposited from Glaciers
Lateral:
Medial: When two lateral moraines intersect
Terminal: The furthest extent of the glacier’s snout
Long Island Ronkonkoma Moraine
Explain:
Pleistocene Glaciation?
Extent? Sea Level Changes? Crustal Depressions?
Pleistocene
The last ice age -
A period of glacial advances and retreats in which land areas covered by glaciers were vast
Extent, Sea Level Changes, & Depressions
Extent: 1/3 of land covered in ice
Sea Level Changes: Drop in sea levels due to growth of continental ice sheets
Associated Crustal Depressions:
The immense weight of the ice sheets causes a depression in the Earth’s crust beneath them.
As ice melts, crust begins to rebound rising the previously depressed land
Define:
Icostasy & Rebound?
Icostasy: Maintenance of the hydrostatic equilibirum of the earth’s crust
Isostatic Rebound: The upward movement of the earth’s crust following Isostatic depression
Explain:
How do glaciers form?
Layers form, causing pressure from snow’s weight
Layers:
Top to bottom Layers
Snow -> Compressses to form
Granular Snow -> then becomes hard into…
Firn (Neve) ->
Glacial Ice
Explain:
Zone of Accumulation?
When there is a net gain of material over a given year (More snow accumulation evaporation)
Explain:
Zone of Ablation?
Why is there still glacier left?
When there is a net loss of glacier materical over a given year (More evaporation than snow accumulation)
Why still glacier left?
Water from zone of accumulation flows downward to zone of ablation thus accumulating onto it
Define:
Glacier Flow?
When accumulation exceeds ablation, the upper regions of glacier receive more ice and snow they lose, the glacier begins to flow under its own weight
Define:
Glacier Advance?
A glacier advances or grows when accumulation consistently exceeds ablation over time
**Cool (Glacial Periods) Climates ** make the glacier increase in size
Accumulation> Ablation
Define:
Glacier Retreat?
When a glacier shrinks, when ablation consistently exceed accumulation
Common during warmer (Interglacial) periods
Accumulation < Ablation
