submergent features

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  • Submergent features
    • Rias: rising sea-levels drown river valleys, middle and upper course of valley= filled with water> high land =dry
      • Cornwall: sea level rose drowning valleys of the rivers flowing off Dartmoor and uplands of Cornwall.
      • Devon: knights bridge estury in south Devon
      • long section ans cross profile of typical river valley, and usually the dendritic system of drainage
    • Fjords: drowned glacial valleys: coasts of Norway,  New Zealand,  Canada, Chile and Greenland.
      • western Scotland: has some but they are not well developed as ice was not as thick or did not last as long.
      • Steep valley sides, straight and narrow, U shaped cross section and hanging valleys on either side
      • unlike Rias  the are not deepest at mouth but consist of a glacial rock basin - shallow section at the end = threshold
        • threshold= reduces glacial erosion as the  glacila comes in contact with sea, thinning the ice
      • formed when sea drown lower part of glacial valley
  • Emergent features
    • Raised beaches: area of former wave-cut platforms + beach above present sea-level.
      • behind beach may find old cliff line with wave-cut notches, sea caves, arches ans stacks
      • common on coast of western Scotland
        • 3 levels has been recognized  8m, 15m and 30m
    • West of the Isle of Arran = well developed raised beach
      • relict cliff, arches, stacks and caves
      • around 4-5 m above sea-level
        • suggests sea has fallen to current level
        • however sea level has risen since last iceage
          • beach has reaches its raised position by isostatic rising  of the land


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