HIGHER REVISION by ert554898

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									HIGHER REVISION


     GEOGRAPHY
     Coasts and mass
       movement.
 Longshore drift in this area has
  been responsible for the
  formation
 of sand bars across the mouths of
  several streams such as those in
  squares 8244 and 8345. When
  sand spits appear on an O.S. map
 the direction of the longshore
  drift can be determined as it will
  be moving towards where the end
  of the spit is being formed. Here,
  however, the direction of the
  longshore drift cannot be
  determined from the map as the
  spits have formed sand bars right
  across the river mouths.
 These bars have trapped water
  which form lagoons at Slapton
 Ley and Lower Ley in 8243 and the
  lake at 818411.
   On this extract, the term ‘point’
    (meaning headland) appears at Warren
    Point, 667421, ‘cliff’ at West Cliff,
    692383 and ‘cove’, indicating where
    erosion has produced a small bay, such
    as Redrot Cove at 668394 and Soar Mill
    Cove at 697376.
   Large headlands at Burgh Island,
    646438 and Bolt Tail, 667396 stand out,
    suggesting a much more resistant rock
    type than in the area that lies in between
    these headlands.
   Smaller headlands like Warren Point and
    Thurlestone Rock, 675414 enclose sandy
    bays like the one at 676416.
   Off the headland there are small islands;
    Mew Stone 725359 and Little Mew
    Stone, 727358. These will be former
    parts of the headland now worn down to
    be stacks or stumps.
   Burgh Island was separated from the
    mainland by erosion. Over time the sand
    shown building up between Burgh Island
    and the mainland may become permanent
    and form a tombolo linking the island to
    the mainland.
   Symbol evidence is also important and we
    see the symbols for cliffs at 688383 and
    steep slopes at 704368.
ROCKFALL
            Rapid, free-fall of
             rock from a steep cliff
             face.
            GRAVITY
            Freeze-thaw action
             loosening the rock.
            Bare lack of
             vegetation.
            well-jointed rock is
             very vulnerable
            A scree slope of fallen
             rock is formed at the
             bottom of the cliff.
LANDSLIP or SLUMPING
           RAPID movements of a
            mass of earth or rock
            sliding along a CONCAVE
            plane.
           Occur after periods of
            HEAVY RAIN, when the
            water saturates overlying
            rock, making it heavy and
            liable to slide.
           PERMEABLE overlying
            IMPERMEABLE
           UNDERCUTTING of a
            steep slope by river or
            sea erosion weakens the
            rock above, also making a
            slump likely.
MUDFLOW
       Occurs on steep slopes
        over 10°.
       It's a rapid sudden
        movement
       Occurs after periods of
        heavy rain or RAPID
        SNOWMELT.
       Not enough
        VEGETATION to hold
        the soil in place,
        saturated soil flows over
        impermeable sub soil.
SOIL CREEP    Very slow movement,
               occuring on very gentle
               slopes
              Soil particles
               repeatedly expand and
               contract in wet and
               dry periods.
              When wet, soil
               particles increase in
               size and weight, and
               expand at right angles.
               When the soil dries
               out, it contracts
               vertically.
              As a result, the soil
               slowly moves
               downslope.
Describe and explain the
      hydrograph.

								
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