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
Explain:
Calving?
When there are glacial parts breaking off due to glacial melting
Define:
Ice Shelf?
Outlet glacier projecting over the sea
Explain:
Periglacial Processes?
Erosion or deposition at the bounaries of glaciers
Define:
Glacier Plucking?
When glaciers scrape along the glacier bed taking pieces of land that joins the ice
Explain:
Roche Moutonee?
Water from the stoss side of a mountain is pushed up by glacial abrasion then as it moves down the lee side glacial plucking happens as the water seeps into the cracks joining the glaciers and being eroded
