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62 Cards in this Set
- Front
- Back
How does glacier ice form? |
Compaction of Snow
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Describe how compaction of snow occurs? |
Steady accumulation of snow over time squeezes air out of snow crystals and gradually compacts them until they become ice.
Note: This is different from the formation of ice cubes in a household freezer. |
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Where will glaciers only form? |
Above a permanent snowline.
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How does the height of the permanent snowline vary? |
It will vary according to climate:
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What two locations is their a permanent snowline? |
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Where can it also be said glaciers form? |
In locations with high:
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What are the two basic types of glaciers? |
Continental Glaciers (ice sheets)
Alpine (mountain) Glaciers Cirque Glaciers Valley Glaciers
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Define: Continental Glaciers |
Large Ice Sheets
Such as those found in Greenland and Antartica
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How large can Continental Glaciers be? |
Example: Antarctica |
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Define: Alpine (mountain) Glaciers. |
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Define: Cirque Glaciers |
Note: In the same way that small tributary streams feed larger rivers. |
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Which two zones do Alpine Glaciers consists of? |
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Define: Ablation Zone |
Mass loss through melting and other processes. |
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Define: Accumulation Zone |
Mass gain from snowfall, wind-blown snow etc. |
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What determines which zone an alpine glacier will consist of? |
By which process is dominant over the course of a year. |
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What are the Ablation and Accumulation zones separated by? |
The Equilibrium Line |
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Define: The Equilibrium Line |
Where mass gain and mass loss are equal. |
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What two ways do glaciers move? |
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Define: Internal Flow |
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Define: Plastic Flow |
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Define: Basal Slip |
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What is the movement of glaciers referred to as? |
Flow |
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Is ice near the surface under much strain? |
No, there is not must overlying ice.
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What are the cracks near the surface of a glacier known as? |
Crevasses
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Where do Crevasses form? |
Wherever the stresses at the surface of a glacier exceed the ice's ability to deform. |
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What is the best example of where Crevasses form? |
Where a glacier drops over a steep step.
Example: The Khumbi icefall on Mt. Everest.
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What are two glacial erosion processes? |
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Define: Plucking |
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What is a classic example of plucking? |
The Roche Moutonnee
Relegation Flow
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Define: Abrasion |
Particles within the ice act like sandpaper to smooth and polish the surface below.
Note: Works just as it does with rivers and with wind. |
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Before Preglacial
During Post Glacial
After Post Glacial |
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What six characteristic landforms do Alpine Glaciation produce? |
H.A.C.T.H.H.
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Define: Horns
H. A.C.T.H.H. |
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Define: Aretes
H. A. C.T.H.H. |
Created when two glaciers on opposite sides of a mountain erode back toward each other far enough to leave a narrow ridge between them.
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Define: Cirques
H.A. C. T.H.H. |
Bowl-shaped depressions that eroded out at the head of glaciers.
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Define: Truncated Spurs
H.A.C. T. H.H. |
Ridge that descends toward a valley floor from a higher elevation.
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Define: Hanging Valleys
H.A.C.T. H. H. |
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Define: Hanging Waterfalls
H.A.C.T.H. H. |
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Define: Till |
Material that is deposited directly by the ice.
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What two forms does glacial deposition take? |
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Define: Moraines |
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What are some features included in Moraines? |
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Define: Lateral Moraine |
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Define: Pro-Glacial Lake |
Formed by either the damning action of a moraine or ice damn during the retreat of a melting glacier.
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Define: Terminal Moraine |
Till sediments that were deposited by glaciers during their greatest advance stage.
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Define: Outwash |
Glacial Deposition process in which material:
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What are the four features of glacial deposition left behind by large ice sheets (continental glaciers)? |
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Define: Eskers |
Long sinuous ridges of stratified drift that meander and have tributaries.
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Define: Drumlins |
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Define: Kettle Lakes |
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Define: Outwash Plains |
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What glacial features are in the US and where are they? |
Depositional In the Midwest
Erosional Yosemite Valley |
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What is unusual about the glacial features in the US? |
There are now no glaciers in those places. |
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What can we deduce from the presences of glacial features in the US but no glaciers? |
Climate must have been different in the past.
Note The generally-accepted picture is that large glaciers were at their greatest extent around 18,000 BP. |
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When was the Glacial Maximum? |
18,000 BP
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What did Glacial Maximum include? |
The greatest extent of the Laurentide ice sheets in North America. |
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What else was happening around the time of the Glacial Maximum? |
Lake Bonneville and other western us Paleolakes were also forming. |
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Was there only one cold period in Earth's history - 'The Ice Age'? |
No. The glacial maximum was just one cold period among many throughout earth's history.
Note: The term 'Ice Age' is therefore inappropriate.
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Define: Ice Age |
Technically an ice age is when Earth has ice at the poles.
Note We're still in an ice age now. |
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How often has earth undergone temperature cycles? |
Many times, both...
Note: Roughly one cycle (cold and warm) every 100,000 years. |
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What is the main cause of climate change? |
Variations of Earth's orbit.
Note: Most certainly the trigger for glacial and interglacial cycles. |
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Can smaller climate fluctuations occur within the larger patterns? |
Yes. Example
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