Term
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Definition
is a large mass of ice,
resting on land or floating in the sea:
– Cover ~11% of Earth’s land area today |
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Term
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Definition
Alpine Glaciers
Continental Glaciers |
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Term
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Definition
Glaciers in mountain ranges are termed
‘alpine glaciers’ |
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Term
| A valley glacier is confined within a valley: |
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Definition
– Range in length from 100m to over 100 km
– Erodes bedrock while flowing slowly downhill
– Transports and deposits debris
– A cirque is a bowl-shaped recess at the head
of the valley |
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Term
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Definition
A continental glacier is a continuous mass of
ice on continents |
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Term
A continental glacier is a continuous mass of
ice on continents |
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Definition
| – Blankets 80% of Greenland and 90% of Antarctica |
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Term
Underlying crust is isostatically depressed
due to the enormous weight of the ice: |
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Definition
Crust depressed more than 2,000 m below sea
level in Greenland and Antarctica |
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Term
Continuous ice cover also associated with
mountains: |
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Definition
– Ice cap is roughly circular and covers less than
50,000 km2
– Ice field has elongated pattern with ridges and
peaks visible above the buried terrain |
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Term
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Definition
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Term
Glacier is an open system:
– Inputs: |
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Definition
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Term
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Definition
| Ice, meltwater and water vapor |
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Term
On the lower end below the firn line, glacier is wasted
via ablation by several processes: |
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Definition
– Melting on the surface, internally and at the base
– Ice removal by deflation (wind)
– Calving of ice blocks
– Sublimation |
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Term
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Definition
is where accumulation gain balances
ablation loss |
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Term
Rates of glacial flow ranges from almost
nothing to 1-2 km/yr: |
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Definition
– Depends on rate of snow accumulation
– Flowing glacier can develop crevasses |
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Term
| Glacier can lurch forward in a surge |
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Definition
Possible cause is build-up of water pressure
underneath |
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Term
Passing glacier can pluck and remove
rock material via erosion: |
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Definition
Embedded rock can scour the landscape
through abrasion as the glacier moves |
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Term
| Glacial erosion can convert |
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Definition
a V-shaped
stream valley into a U-shaped valley |
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Term
| Two eroding cirques can create a |
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Definition
saddlelike
depression in between called a ‘col’ |
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Term
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Definition
results from several cirques
gouging a mountain summit from all sides |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| are a series of circular lakes |
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Term
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Definition
forms when a glacial trough
intersects an ocean and seawater flows
inland |
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Term
| Glacial drift consists of |
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Definition
unsorted and
sorted glacial deposits (rocks & sediment): |
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Term
Glacial drift consists of unsorted and
sorted glacial deposits (rocks & sediment): |
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Definition
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Term
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Definition
| unstratified (non-layered) and unsorted |
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Term
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Definition
(layered) drift deposited by glacial
meltwater |
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Term
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Definition
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Term
Moraines are specific landforms produced
by deposition of glacial sediment |
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Definition
Lateral moraine forms on either side of glacier
– Lateral moraines may merge to form medial
moraine
– Terminal moraine marks the glacier’s furthest
extent |
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Term
| Continental glaciers form |
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Definition
across
broad, open landscapes |
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Term
Most erosional and depositional
features are |
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Definition
associated with glacial
retreat: |
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Term
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Definition
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Term
Outwash plains of stratified drift
deposited by |
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Definition
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Term
Other features associated with Continental
Glaciation: |
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Definition
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Term
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Definition
Sinuous, narrow ridge of coarse sand and
gravel that formed by meltwater stream that
flowed beneath glacier |
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Term
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Definition
Hole left behind after large block of ice
melts |
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Term
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Definition
Small hill or knob of poorly-sorted sand
and gravel |
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Term
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Definition
Elongated deposit of till streamlined in
the direction of continental ice movement |
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Term
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Definition
Located in subarctic and polar climates
(tundra) |
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Term
Landscapes consists of frost weathering
and freeze-thaw shattering of rock: |
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Definition
Some associated with near-permanent ice
– Others at high elevation and seasonally snowfree |
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Term
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Definition
soil or rock
remain below freezing for at least two years
but is not covered by glaciers |
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Term
The freezing of water in soil and rock
initiates frost action |
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Definition
– Expansion of water as it freezes fractures rock
and disrupts soil |
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Term
Saturated soil and rocks are subjected to
large displacements when freezing: |
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Definition
– Vertical movement called frost heaving
– Horizontal motions called frost thrusting |
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Term
Proper construction in
periglacial environments
requires |
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Definition
raising of buildings
and pipes above ground |
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Term
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Definition
| The Last 1.6 Million Years |
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Term
During the early 20th century, four major
glacial advances were recognized and
mapped in North America: |
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Definition
Wisconsin (maximum ~18,000 years ago)
– Illinoian (ended ~130,000 years ago)
– Kansan
– Nebraskan (~2 m. |
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Term
| Three to five were recognized in |
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Definition
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Term
Recent studies of deep-sea cores indicate
many |
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Definition
more glacial episodes than were
recognized on land |
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Term
| Diverse Effects of Last Ice Age |
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Definition
| Changes in oceanic circulation patterns |
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Term
Glaciers locked up abundant water on
continents, lowering sea level: |
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Definition
Coral reefs high and dry
– Continental shelves and land bridges exposed
– Rivers crossed exposed shelves, cutting canyons
– On land, downcutting by rivers formed terraces |
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Term
| Sea Level Drop Lowered Base Level |
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Definition
Causing Streams
On Land To Downcut And Form Terraces |
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Term
Pleistocene Glaciation
(~18,000 years ago |
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Definition
• Several major ice centers
in Canada
• Low-stand of sea level
• Bering Land Bridge |
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Term
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Definition
Following retreat of glaciers after the
last ice age, crustal rebound occurred
around Hudson Bay, Canada, and the
northern Baltic Sea over the last
10,000 years |
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Term
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Definition
| Ice dam first broke ~ 15,000 years ago |
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Term
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Definition
Derived from outwash plains of glacial
meltwater |
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Term
Derived from outwash plains of glacial
meltwater |
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Definition
– Meltwater carried large volumes of sediments from
melting ice sheets; sediments deposited in
outwash plain |
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Term
During the fall and winter, melting of ice
sheets ceased |
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Definition
– Flow of meltwater either ceased or was greatly
reduced
– Unvegetated floodplains dried out and were
exposed to the wind
– Glacially ground flour-like silt and clay winnowed
by the wind
– Particles blown downwind and deposited as loess
deposits |
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Term
Western U.S. was dotted with large
lakes 12,000 – 30,000 years ago: |
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Definition
A time of wetter conditions during
glaciation |
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Term
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Definition
Lacustrine Deposits: Lake sediment that
form terraces along former shorelines |
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