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Unformatted text preview: . Wet based, water at bottom Polar glaciers ice is well below melting temp... dry based ,. frozen at bottom How do glaciers move? o Internal deformation: dry (frozen) based, polar glaciers o Basal sliding: wet based, temperate glaciers Movement of Glacial Ice o Two types of mechanical behavior in glacial ice Brittle behavior- uppermost 60 meters of ice Tension causes crack to form in brittle ice Plastic behavior- lowermost ice if ductile Plastic flow occurs beneath 60 meters o Flow rates- 10 to 300 m/yr o Surge-rare, rapid flow (20 to 110 m/day) o The rate of flow is controlled by... Slope angle: steeper= faster Basal water: wet bottom=faster Location within glacier. Greater velocity in ice center Friction slows ice at margins Glacial Flow o Alpine glaciers flow down slope o Ice sheets flow outward from a central point...
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- Spring '08