Glaciers

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Formation of Glacial Ice from Snow

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Figure 15-5 Mechanics of Glacial Flow

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Deeply Crevassed Davidson Glacier near Haines, Alaska

Source: Breck P. Kent

Crevasses

Video: Crevasses Essentials of Geology, 15a–6

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Types of Glaciers (cont’d) –

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Types of Glaciers (cont’d) – Angel Glacier

Source: Comstock

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Types of Glaciers (cont’d) – Valley (Alpine) Glacier

Source: Tom Bean

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Types of Glaciers (cont’d) – Icecap

Source: Betty Crowell/Faraway Places

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Types of Glaciers (cont’d) – Tidewater Glacier

Source: Jim Wark/Peter Arnold, Inc.

Continental Glacier

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Glacial Erosion

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Deposition by Glaciers

• Till - a mixture (unsorted) of boulders, sand, clay and silt. Glaciers have filled entire valleys w/ till making them flat.

• Outwash - material deposited by the glacier as it melts, similar to river deposits. Outwash is sorted or separated by the size of its particles. (boulder, gravel, sand, silt)

lateral moraine

medial moraine

Till Erosion

• Moraine - mounds of materials deposited along the sides, in the middle or at the end of the glacier as it stops moving & begins to melt.

Till Erosion

• Erratic – Large boulders dropped by glaciers

Outwash

Large Sediment

Med Sediment

Small Sediment

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Glacier

melting

Depositional Features (continental glaciers)

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How do Ice ages occur? Land bridge Formation

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Milankovitch Cycles

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Milankovitch Cycles (cont'd)

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Milankovitch Cycles (cont'd)

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Milankovitch Cycles (cont'd)

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Changes In Global Climate During the Cenozoic Era

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Effects of North American Ice Sheet

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Geology at a Glance The Work of Continental Glaciers

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Geology at a Glance The Work of Alpine Glaciers