2 c there is no life in antarctica except near the

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Unformatted text preview: •The lowest recorded temperature is -89.2 °C. •There is no life in Antarctica except near the coast Types of Glaciers – Piedmont & mountains Piedmont of Tidewater Piedmont: Originally confined alpine, spread at foot Source: Jim Wark/Peter Arnold, Inc. Calving Iceberg Calving – Hubbard Glacier, Wrangell-St. Elias National Park, Alaska Hubbard Releases fresh water to oceans, CO2 to atmosphere. A Glacier’s Budget Glacier’s • Budget = Gain – Loss • Gains snow in zone of accumulation • Loses ice in zone of ablation • Budget can be positive (net growth) • Static • or negative (net melting) A Glacier’s Budget Glacier’s Year round Snow Summer Rain Note that a glacier is a river. Even if the terminus doesn’t advance, still flows Glacial Flow Glacial • Internal deformation – Ice crystals slide past one another • Basal Sliding – Entire glacier slides downhill on a thin film of meltwater at its base. • Glacier always flows toward zone of ablation Mechanics of Glacial Flow Mechanics Erosion by Glaciers Erosion • Abrasion – Rocks embedded in glacier’s base make linear scratches and grooves in bedrock • Quarrying – Glacier breaks off and removes large blocks of rock. FROST WEDGING is important Glacial Abrasion in Bedrock Glacial Source: Tom Bean Glacial Erosion – Roche Moutonée Glacial Glacial Erosion – Roche Moutonée Glacial Yosemite NP, Calif Erosion by Glaciers (cont.) Erosion • Alpine glaciers erode mountain slopes Alpine into horseshoe shaped basins called cirques cirques – Melting forms cirque lake (tarn) • Erosion of two or more cirques erodes Erosion intervening rock intervening – Horns :pointy peaks made by trios – Arêtes: long serrated ridges by pairs – Cols: passes through the arêtes Alpine Glacial Erosion Alpine Alpine Glacial Erosion Alpine Origin of Hanging Valley Yosemite Falls Yosem...
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