Glaciers

Glacier - a thick ice mass that originates on land from the accumulation, compaction, and recrystallization of snow. Formation of glacial ice from snow

1. Ice sheets, Continental glacier Glacier Types 1. Ice sheets, Continental glacier Large scale – cover 10% of Earth’s land Greenland – 1.7 million km2 Antartica – 13.9 million km2

Continental Glaciers

2. Valley, Mountain, Alpine Glacier Types 2. Valley, Mountain, Alpine Smaller than ice sheets Lengths greater than widths Only cover a small region

Alpine Glaciers

Greenland

Bylot Island, Canada

Glacier movement 50 meters 100 meters

Glacier movement

Glacier movement Plastic flow – flowing solid 200 m/yr Basal slip – movement over bedrock 200 m/yr http://www.youtube.com/watch?v=xRZaDJxFjIA

http://www.youtube.com/watch?v=sJmWQk492W0 http://www.youtube.com/watch?v=89sOW-FzolI https://www.youtube.com/watch?v=hC3VTgIPoGU

Glacier movement Rotation of Grains Melting & Freezing Internal Slipping

Glacier budget In: Zone of accumulation – snow accumulates Out: Zone of ablation – general term for loss of ice or snow from a glacier Melting Calving - icebergs

Glacier budget

Glacial Calving

Dry calving with recumbent folds

Sub-glacial River

Surface Drainage

Glacier Erosion Plucking – loosen and lift blocks of rock Abrasion – rock flour Striations – grooves scratched in bedrock

Glacial Landforms Mountian Glaciers – tend to accentuate the landscape Continental Glaciers – tend to subdue the landscape

Mountain Glaciers

Mountain Glaciers Landforms Hanging valley – a tributary that enters a glacial trough high above the floor of the trough. Arete – a narrow , knifelike ridge separating two adjacent glaciated valleys. Horn – a pyramid-like peak formed by glacial action in three or more cirques surrounding a mountain summit.

Mountain Glaciers Landforms Tarn – a small lake in a cirque. Cirque – an ampitheater-shaped basin at the head of a glaciated valley. Truncated spurs – eroded triangular shaped cliffs in glaciated valleys. Glacial trough – U-shaped glacial valley

Mountain Glaciers

Ice Dammed Lake

Glacial Deposits Drift (general term) – Sediment deposited on land or in water as a result of glaciation. 1. Till – Unsorted debris transported by glaciers and deposited on land. 2. Sorted Sediments – Sediments transported by melt water are deposited in Eskers and in the Outwash Plain.

Till Deposits Moraines - a pile of debris that has been transported and deposited by a glacier Erratics - boulders left on the surface

Erratic

Terminal Moraine - Debris pushed along in front of the glacier Ground Moraine - debris accumulated under the glacier