Periglacial Systems

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  • Created by: roror
  • Created on: 17-05-18 11:36
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  • Periglacial Systems
    • Landforms
      • Ice Wedges
        • Narrow cracks filled with ice. Milky appearance due to air bubbles
        • Cold, continuous permafrost
          • In summer, small crack is filled with meltwater. Freezing causes soil to contract. Widens and deepens crack to form wedge
            • In warmer climates, ice can be melted and replaced with sediment- ice-wedge cast
      • Pingos
        • Open System
          • Discontinuous permafrost
          • Water seeps into upper ground and flows under pressure to flat areas between permafrost and frozen ground beneath
            • Water freezes into an expanding ice lens, pushing up low land above it
          • Hydraulic ice core
        • Closed System
          • Continuous permafrost
          • Permafrost layer at lakebed is insulated so thaws
            • Sandwiched between lake and underlying permafrost
              • Lake drains so lakebed isn't insulated and freezes
                • Due to pressure differences, newly freezing water gathers to form an expanding ice lens
                  • Sediments are pushed up to form a dome
          • Hydrostatic ice core
      • Terracettes
        • Small steps running horizontally along contours of a slope
      • Thermokarst
        • Depressions in surface from melting permafrost= HUMANS
      • Patterned Ground
        • Circles, nets, stripes, steps, polygons
        • Ice crystals develops, causing increased volume of soil and upwards expansion of soil surface
      • Permafrost

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