arête

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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.

 

calving

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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.

 

cirque

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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.

 

continental glacier

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

 

crevasses

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A crack in a glacier caused by rapid extension. 

drumlins

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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.

 

erratics

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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.

eskers

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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.

firn

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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.

glacier

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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.

 

glacial trough

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

horn

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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.

 

ice caps

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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.

ice front

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

ice sheet

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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.

kames

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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.

 

kettles

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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.

 

moraine

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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.

 

nunataks

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

outwash

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

outwash plains

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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.

rock flour

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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.

 

roches moutonnees

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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.

 

snowline

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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.

 

striations

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

 

till

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

 

valley glacier

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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.