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All About
Glaciers *
Vocabulary
alpine glacier
-is a valley glacier.
Alps
-are a prominent mountain range in southern Europe.
arete
-is a skinny mountain ridge
shaped on opposite sides by a series of glacial cirques.
-arete diagram
-arete-Mt.Whitney
avalanche
-is a large mass of snow that rapidly slides down a slope.
bergschrund
-is the large crack at the
top of a valley glacier where it is pulling away from the mountain.
-bergschrund diagram
cirque
-is a scoop-like depression
on the side of a mountain formed by a valley glacier eroding the
mountain.
-cirques, Kebler Pass, Colorado
-Rocky Mountains Park-cirque-1
-Rocky Mountains Park-cirque-2
continental glaciation
-occurs when glaciers cover a large portion of a
continent. Modern examples are Greenland and
the Antarctic.
crevasse
-is a very large crack on top of a glacier
crustal rebound
-During an ice age the
weight of a thick continental glacier presses the crust of the earth down.
After the glacier melts, the crust slowly rises up to its previous elevation.
drumlin
-is a long, skinny,
cigar-shaped hill that has be sculpted by a glacier flowing over it.
-drumlin diagram
erratic
-is a boulder far removed from its original source and deposited by a glacier.
-Yosemite-glacial grooves and erratics-1
-Yosemite-glacial grooves and erratics-3
esker
-is a snakelike ridge of
water lain gravel deposited by a steam flowing beneath a melting glacier.
-esker diagram
fiord
-is a U-shaped glacial
valley that is partially flooded by seawater.
-fiord diagram
-fiord-Opal's
Pals
firn
-is glacial ice, a granular
form of ice similar to the material in a "slush ball".
-glacial
ice-firn-Opal's Pals
frost wedging
-Water gets into a crack,
freezes, and expands. The tremendous pressures exerted by the
expansion of
water into ice can cause the rock to split further.
glacial grooves
-As a glacier moves across
bedrock, the large rocks that the glacier is dragging along gouge long
grooves.
glacial plucking
-is the process where
glacial ice is frozen in cracks and as the glacier moves the ice pulls rock
fragments out of the bedrock.
-glacial plucking-Mt.Whitney
glacial polish
-A glacier moving across a
bedrock surface can polish the bedrock by abrasion with the fine rock
material
embedded in the ice.
-Mt.
Whitney-glacial polish
-Mt. Whitney-glacial polish-B
-Mt.Whitney-glacial
polish-D
glacial striations
-are scratches left on
boulders and cobbles and bedrock as rocks are dragged along by a glacier and rubbed
against
each other during the movement. Also includes large, long, linear features
-glacial striations-Mt. Whitney
-Montana-
glacial striations*
glacial till
-is the unsorted rock debris, ranging from boulders to silt, that are left behind when a glacier melts.
glacier
-is a moving mass of ice on land that is at least 150 feet thick
hanging valley
-is a small U-shaped
glacial valley exposed on the upper side of a larger U-shaped glacial valley.
The smaller valley was formed in colder times by a tributary valley glacier
meeting up with a
larger valley glacier.
-hanging valley diagram
horn
-is a mountain with very
steep slopes which was carved with cirques on three or more by valley
glaciers.
The most famous glacial horn is the Matterhorn in Switzerland.
-Rocky Mountains Park-horn and cirques
Ice Ages
-are distinct times in the
history of the Earth when major portions of the continents were covered
by
glaciers.
kettle
-is a small lake surrounded by glacial till. A kettle is
formed by a depression created by the
melting of a large piece of glacial ice
covered over with till.
-kettle lake diagram
lateral moraines
-are the piles of glacial
till deposited along the sides of a glacier.
-moraine diagram
loess
-is a very fine, silty
material that started out as rock flour (rocks ground up by glacial action to a
fine powder), but is now a wind-deposited soil.
medial moraine
-When two valley glaciers
merge to form a larger valley glacier, their area of contact is often
marked by
a line of glacial debris accumulated from lateral moraines of the two glaciers.
outwash plains
-are flat land areas
covered by the silty material carried by streams flowing away from a melting
glacier.
permafrost ground
-is semi permanent frozen ground.
rock flour
-is rock that has been crushed and ground to a fine powder by glacial action.
terminal moraine
-is the pile of glacial
till at the base (snout) of a glacier.
-moraine diagram
U-shaped valley
-is created when a valley glacier scrapes out the bottom
and sides of the valley that it is moving
through.
-U-shaped glacial valleys, Kebler Pass, Colorado
-Rocky Mountains Park-U shaped valley-1
-Rocky Mountains Park-U shaped valley-2
valley glacier
-is a glacier in a mountain valley. A valley glacier is also known as an alpine glacier.
Wisconsin Ice Age
-is the most recent of the
Pleistocene advances of glaciers moving across North America. The
Wisconsin Ice
Age ended about 15,000 years ago.
zone of ablation
-is the portion of a glacier below the snowline where the glacier is melting.
zone of accumulation
-is the region of a glacier
above the snow line where ice in the form of snow is being added to the
glacier.
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