Glaciers 2024-25_Thompson

glacier

A large mass of ice formed from compacted snow that moves slowly over land due to gravity and can carve the landscape as it advances.

Louis Agassiz

A geologist known for his contributions to the study of glaciers and for establishing the theory of the Ice Age.

ice age

A period marked by significant global cooling or warming, resulting in the advance or the retreat of glaciers and ice sheets over large areas of the Earth.

Laurentide ice sheet

A massive ice sheet that covered much of Canada and parts of the northern United States during the last Ice Age

Pleistocene

The most recent/current Ice Age that lasted from about 2 million to 11,000 years ago, characterized by repeated glacial advances and retreats.

firn

A granular ice formed from compacted snow that can develop into glacial ice over time.

continental glacier

An extremely large ice mass that covers a significant land area and flows outward from its center. Has a dome shape. Examples are Antarctica and Greenland.

nunatak

A mountain peak or ridge that rises above a glacier or ice field, remaining exposed due to its elevation.

valley glacier

long and narrow glacier that flows in valleys within mountain ranges. Smaller scale than continental glaciers

plastic flow

is a type of glacier movement occurring in the interior of a glacier, where the ice deforms and flows slowly under pressure.

crevasse

A deep crack or fissure in a glacier's surface, often formed by the movement of ice and the stress of its weight.

basal slip

the movement of a glacier where the ice slides over the bedrock due to meltwater acting as a lubricant, allowing it to move more rapidly.

striations

grooves or scratches on rock surfaces caused by the movement of glaciers, indicating the direction of ice flow.

cirque

A bowl-shaped depression carved by a glacier. It forms at the head of a glacier and is typically surrounded by steep cliffs.

arete

a sharp ridge formed between two cirques.

horn

a pyramid-shaped peak formed by multiple cirques meeting each other at the summit of a mountain.

col

A low point or “saddle shape” between two mountains, typically formed by the erosion of glaciers on either side. Two cirques will be on either side of the col

trough

a long, U-shaped valley carved by glacial erosion

till

unsorted sediment deposited directly by a glacier, including clay, silt, sand, gravel, and boulders.

zone of ablation

The area where glacier ice melts, sublimates, or calves away, resulting in a loss of ice mass.

erratic

a rock or boulder that has been transported by a glacier and deposited in an area different from its source.

moraine

A accumulation of debris, such as soil and rocks, that has been pushed along or deposited by a glacier.

kettle pond

a depression left by a melting glacier, often filled with water, creating a small lake or pond. Example is Walden Pond