FLUVIOGLACIAL PROCESSES (MS NYE)

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  • Fluvioglacial Processes
    • Outwash Plains
      • created by erosion / deposition from melt water
      • when melt water merges from snout, loses its energy (no longer flowing under hydrostatic pressure)
        • material being carried is deposited (largest first - forms an alluvial fan at end of glacier)
          • number of alluvial fans are formed = outwash plain
      • finest material = carried furthest = sorting of sediment by size
      • often stratified = sediments laid down in layers during annual flood event + during periods of high discharge (summer = more melting)
      • braided streams = highly variable discharge of melt water and deposition causes river to splitinto smaller streams
        • lateral erosion from these streams = helps to create flat layered feature
    • Eskers
      • winding/sinuous ridges of often coarse sand/gravel deposited by melt water
        • formed within subglacial tunnels running underneath glacier
          • these streams, under hydrostatic pressure, carry large amounts of sediment + also run off shallow gradients
            • during deglaciation, as glacier retreated, sediments = deposited forming long, sinuous narrow ridges of sorted sand/gravel
    • Kettle Holes
      • found in zones where dead ice was left on an outwash plain by a retreating glacier
        • as melt water streams emanated from the ice, they buried blocks of dead ice under deposits of sorted and stratified sediments
          • ice melted and left a depression in outwash plain = kettle hole
    • Melt water channels
      • erosional landform = created by melt water
      • aka glacial overflow channels
      • form from original course followed by a  river before glaciation, may be blocked by ice, or as an overflow from a proglacial lake
        • huge releases of water = energy to erode and carve out deep gorges (abrasion/hydraulic action)
      • Examples: Newtondale and Lake Pickering
    • Kames
      • depositional feature
      • rounded mounds/hills of fluvioglacial deposits
      • found near end of former glacier as began to retreat
      • melt water held back by terminal moraine led to formation of lakes
        • material was deposited where the melt water left the glaciers to flow into lakes (creating delta-like landforms)
          • when ice supporting the up-valley side melted, material collapsed back to form the kame

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