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MVG's BSS ESC11 CHPT 11 Vocab
Glaciers
27
Science
11th Grade
12/14/2008

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Term

arête

 

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Definition

 

A jagged, narrow ridge that separates two adjacent glacier valleys or cirques. The ridge frequently resembles the blade of a serrated knife. A French term referring to the bones in a fish backbone.

 

Term

calving

 

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Definition

 

The process by which pieces of ice break away from a glacier that ends in a body of water or from the edge of a floating ice shelf that ends in the ocean. Once they enter the water, the pieces are called icebergs.

 

Term

cirque

 

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Definition

 

A bowl-shaped, amphitheater-like depression eroded into the head or the side of a glacier valley. Typically, a cirque has a lip at its lower end. The term is French and is derived from the Latin word circus.

 

Term

continental glacier

 

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Definition

 

A continental glacier is a huge mass of ice that covers a large area of land near the Arctic or Antarctic polar regions.

 

Term

crevasses

 

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Definition

 

A crack in a glacier caused by rapid extension. 

Term

drumlins

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Definition

 

An elongated ridge of glacial sediment sculpted by ice moving over the bed of a glacier. The shape is often compared to an inverted, blunt-ended canoe. Generally, the down-glacier end is oval or rounded and the up-glacier end tapers.

 

Term

erratics

 

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Definition

 

A rock of unspecified shape and size, transported a significant distance from its origin by a glacier or iceberg and deposited by melting of the ice.

Erratics range from pebble-size to larger than a house and usually are of a different composition that the bedrock or sediment on which they are deposited.

 

Term

eskers

 

 

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Definition

A meandering, water-deposited, generally steep-sided sediment ridge that forms within a subglacial stream channel. 

 

Generally composed of stratified sand and gravel, eskers can range from feet to miles in length and may exceed 100 feet in height.

Term

firn

 

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Definition

 

An intermediate stage in the transformation of snow to glacier ice. Snow becomes firn when it has been compressed so that no pore space remains between flakes or crystals, a process that takes less than a year.

Term

glacier

 

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Definition

 

Glaciers are classified by their size, location, and thermal regime.

 

A large, accumulation of ice, snow, rock, sediment and liquid water originating on land and moving down slope under the influence of its own weight and gravity.

 

Alpine Glaciers are found in mountain ranges and act like a dynamic river of ice.

 

Continental Glaciers or Ice Caps cover large areas of a landmass.

 

Term

glacial trough

 

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Definition

 

Steep-sided, flat-bottomed valley formed by a glacier. A U-shaped valley.

Term

horn

 

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Definition

 

A pointed, mountain peak, typically pyramidal in shape, bounded by the walls of three or more cirques. 

 

When a peak has four symmetrical faces, it is called a Matterhorn.

 

Term

ice caps

 

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Definition

 

An ice cap is a large mass of ice that originates on land by compaction and recrystallization of snow. Ice caps flow outwards in several directions and cover most or all features of underlying land.

Term

ice front

 

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Definition

 

An ice front is the place where a glacier thins and ends. The ice front's position changes as the glacier moves or melts

Term

ice sheet

 

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Definition

 

An ice sheet is a mass of glacier ice that covers surrounding terrain and is greater than 50,000 km².

 

The only current ice sheets are in Antarctica and Greenland.

 

Term

kames

 

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Definition

 

A sand and gravel deposit formed by running water on stagnant or moving-glacier ice. 

 

Kames form on flat or inclined ice, in holes, or in cracks.

 

A kame terrace forms between the glacier and the adjacent land surface. Shapes include hills, mounds, knobs, hummocks, or ridges.

 

Term

kettles

 

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Definition

 

A depression that forms in an outwash plain by the melting of a block of glacier ice that was separated from the retreating glacier and was subsequently buried by glacier sedimentation. As the buried ice melts, the depression enlarges.

 

Term

moraine

 

 

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Definition

 

A general term for unstratified and unsorted deposits of sediment that form through the direct action of, or contact with, glacier ice.

 

Many different varieties are recognized on the basis of their position with respect to a glacier.

 

Term

nunataks

 

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Definition

 

A mountain peak or ridge that pokes through the surface of an Ice Field or a Glacier.

Term

outwash

 

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Definition

 

Glacially eroded, sorted sediment that has been transported by meltwater. Typically, the sediment becomes finer grained with increasing distance from the glacier terminus.

Term

outwash plains

 

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Definition

 

A broad, low-slope angle alluvial plain composed of outwash that has been transported by meltwater. The alluvial plain begins at the foot of a glacier and may extend for miles.

 

Typically, the sediment becomes finer grained with increasing distance from the glacier terminus.

Term

rock flour

 

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Definition

 

Fine-grained, silt-size sediment formed by the mechanical erosion of bedrock at the base and sides of a glacier by moving ice. When it enters a stream, it turns the stream's color brown, gray, iridescent blue-green, or milky white. Also called Glacier Flour or Glacier Milk.

 

Term

roches moutonnees

 

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Definition

 

An elongated, rounded, asymmetrical, bedrock knob produced by glacier erosion. It has a gentle slope on its up-glacier side and a steep- to vertical-face on the down-glacier side. Sometimes called rock drumlins.

 

Term

snowline

 

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Definition

 

A term generally used to refer to the elevation of the lower edge of a snow field. It is not truly a line but rather an irregular, commonly patchy border zone. The higher the latitude or altitude, the lower the snowline.

 

On glacier surfaces the snow line or névé line is the outer limit of winter snow cover on a glacier.

 

Term

striations

 

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Definition

 

Multiple, generally parallel, linear grooves, carved by rocks frozen in the bed of a glacier into the bedrock over which it flows.

 

Term

till

 

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Definition

 

An unsorted and unstratified accumulation of glacial sediment, deposited directly by glacier ice. 

 

Term

valley glacier

 

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Definition

 

Commonly originating from mountain glaciers or ice fields, these glaciers spill down valleys, looking much like giant tongues.

 

Valley glaciers may be very long, often flowing down beyond the snow line, sometimes reaching sea level.

 

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