lecture_8 - AMOUNT AND RATE OF GLACIER EROSION Narrow ice...

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LECTURE 8 - GLACIAL EROSION AND RESULTANT LANDFORMS TYPES OF GLACIER EROSION A brasion revealed by smoothing, round., scratch., polish. Plucking abrupt, steep, ragged side on protruderance regelation assisted works best in jointed rocks -> quarrying may exceed ablation rate -> char. basal layer FACTORS CONTROLLING EROSION RATES Temperature warm glaciers erode more Debris harder -> more ablation more tools -> more erosion Water lubricates surface -> retards scratching freezing and thawing -> asset to plucking may be responsible for some fluting , grooves mostly where ice thin Thickness and velocity erosion rate vs. o. b. pres. & shear stress increases then decreases decrease due to pressure melting Resistance and structure of bedrock hardness, jointing, permeability
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Unformatted text preview: AMOUNT AND RATE OF GLACIER EROSION Narrow ice streams (10s km) Yosemite Valley - 450 m Fjord in Norway -> 1000 to 2000 m 900 m basins down at the heels profile Wide ice streams (100s km) Great Slave Lake -> 600 m Great Bear Lake -> 400 m Lake Michigan -> 300 m; -60 asl Laurentide ice sheet (1000s km) drift thick -> average of 10 m low due to low relief and hard rocks with clay perhaps as much as 120 m rates of erosion 0.5 to 5.0 mm per year (1.0 mm average) PRODUCTS OF GLACIER EROSION Small scale striae and striations whalebacks glacial grooves roches moutonnees friction cracks rock drumlins Large scale U shaped valleys cirques spurs arete s tarns horn paternoster lakes col hanging valleys trimline...
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lecture_8 - AMOUNT AND RATE OF GLACIER EROSION Narrow ice...

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