Laste ned presentasjonen
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Axel Heiberg Island, Canada
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Hva er en isbre ? Hvorfor beveger isbreene seg ?
Isbre = snø og ismasse i bevegelse Isen er deformerbar – ”brød-deigen” Isen endrer egenskaper med trykket (istykkelsen) Isen glir
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Folgefonna
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Alaska – flytbevegelse - midtmorener
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Surface velocity us is partly caused by gliding ug and partly deformation ud
Gliding/sliding varies considerably – deformation is almost constant (depending on slope and thickness) us = ug + ud
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Sprekker på breer i Norge – Svalbard - Antarktis
50 m
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Bondhusbreen, Folgefonna
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Bondhusbreen - Folgefonna
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Helikopter- platform Bondhusbreen
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Bondhusbreen - tunnellsystem
Tunnellsystemet under Bondhusbreen Bondhusbreen - tunnellsystem
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Isen deformeres
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Isen deformeres
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Is er en seig masse som endrer egenskaper med trykk og temperatur
Glens flow law - deformation of ice: Liquids:
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Deformation rate h = 160m Glens flow law: ė = A τⁿ Closure rate: dr/dt = A (P/n)ⁿ dr/dt ~ mm/d If P = ρgh = 14 bar, n = 3: A = 0.36 y-1 bar-1 or 11.4 * s-1kPa-3 - twice as high as Peterson
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Nigardsbreen still advanced in 2004
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Artificial roche moutonne (Rundsva) with a boulder in the ice
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Boulder crossing
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Rock wall pressures - water opening- temperatures
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Rock crushing Ice Rock
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Hvordan eroderer breene ?
Skuring Knusing Plukking Erosjon – transport – avsetning
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Rundsva
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Skuring, brunhud, plukking Svenske skjærgården
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Plucking
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