IB Geography - Extreme Environments : Glacial Landforms

Erosion: Pressure release

when overlying materials are removed by erosion, or other processes, which causes underlying rocks to expand and fracture.

Transportation : Bulldozing

Rocks and debris found in front of the glacier are pushed along by the moving ice.

Transportation : Rotational Slip

Semicircular motion of ice as it moves downslope along a concave face. It can help to make hollows in the landscape, deepening them into bowl shapes.

Erosion: Striations

Long scratches created where moraine scraped against resistant rock

Erosion: Cirque/Corrie/Cwm

Steep sided, half-open hollow formed at the head of a glacier

Erosion: Plucking

Basal ice freezes in rock surface cracks. As the main body of the glacial ice moves material around the ice in the cracks is pulled and plucked out.

Erosion: Tarn/Lochan/Corrie Lake

Lake formed by meltwater and/or precipitation in a cwm

Erosion: Horn/Pyramidal Peak

• three-sided, pointed mountain peak

• Formed when 3+ back-to-back corrie glaciers carve away at the top of a mountain

Erosion: Truncated Spurs

Formed where a glacier cuts off interlocking spurs formed by a river

Erosion: Nunataks

Rocky island surrounded by glacial ice

Erosion: Hanging Valley

Formed where the U-shaped valleys of tributary glaciers meet the main U-shaped valley

Erosion: Arête

• knife-edge, steep-sided ridges

• Formed when two corries cut back into the mountainside 

Erosion: Fjord

U-shaped valley flooded by rising sea levels

Erosion: Ribbon/Finger Lake

Lake formed in the depression left by overdeepening by the base of a glacier

Erosion: Glacial Trough

U-shaped valley formed where a glacier has passed

Erosion: Roche Mountonée

Rocks, one side smoothed by abrasion and the other steep and rough from plucking

Deposition: Till

Boulder clay, unconsolidated, variety of particle sizes

Deposition: Erratics

Boulders deposited from the glacier with foreign geology

Deposition: Moraine

Any rock carried by the glacier, lateral, medial, ground, terminal

Deposition: Drumlins

Smooth, elongated mounds of till, steep on one side and gentle on the other, often found in groups

Deposition: Kettle Holes/Lakes

Form from detached blocks of ice, melt and leave behind a depression which often fills with water

Deposition: Glacial Flour

Suspended load of rock dust in water

Deposition: Outwash

Flat areas of meltwater below the snout of glaciers, made from till, eskers, erratics, drumlins all found on this plain

Deposition: Eskers

Long, narrow ridges of sand+gravel, formed by deposits of sub-glacial meltwater streams