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Difference b/w River Alluvial Plains and Glacial Outwash Plain

edited January 2014 in Geography & Geology
Hi Friends,

Can anyone please spot some differences in the Alluvial Plains and Outwash Plains. (In both the cases deposit is very coarse)

thanks in advance.. :)
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Comments

  • edited January 2014
    Alluvial plain:

    River carries silt from upstream > High flow rate due to mountainous terrain keeps things mixed with river water > On plain, river slows > Material sedimints out as course to fine alluvium.

    Courses material sediments out first as it needs higher flow rates to keep it moving.

    (Glacial) Outwash Plains:

    Similar process. Glaceir carries down silt and rocks. Plus the ice also errodes (abbrasive like) the relief, smoothening it out into a plane. Heavier ones settle closer to the sourse; finer goes further and may end up in ensuing rivers as river silt. Since the glacier is made up of ice (solid), heavier material can be dragged down.

    In both cases, there is formation of a plain. Obvious differences include:

    1. Ice vs water
    2. Boulders to pebbles vs pebbles to fine silt
    3. Abbrasive type erosion of ice vs fluid type erosion of water
    4. ElevationFreezing temperature (altitude / high latitude) required to have a glacier for outwash plains
    5. Shape of the valley
    6. Speed of flow
    7. Outwash planes can grow and shrink with seasons deending on how far the glacier expands / receeds.

    Glacial beds, Outwash planes, River sources, Alluvial fans, Flood planes, etc form a continuous series of geomorphology due to ice/water flow. There is bound to be overlap.
  • Anybody with Geography optional? Corrections?
  • @ArindamSarkar

    Thanks Arindam. :) This clears my doubt.
  • @ArindamSarkar

    Thanks Arindam. :) This clears my doubt.

    Just one more thing....you said "elevation req". what does that mean?

    Also, can we write something like this...

    Alluvial plains form when there is change in terrain - river enters to plains from mountains

    While glacial Outwash Plains form when the slope is quite low and the glacier is retreating. ??
  • edited January 2014
    Elevation is required for glaciers to form and move about as ice. Outwash planes are closer to the highlands. They from from the terminal part of glaciers and are restricted to colder areas. I guess, elevaation would not be the correct term to use. It's also possible in high latitudes. Freezing temoerature is more apt. Alluvial plains can extend to the sea and occur with flowing water (warmer).
    Alluvial plains form when there is change in terrain - river enters to plains from mountains
    - That sounds about right.
    Glacial Outwash Plains form when the slope is quite low and the glacier is retreating.
    - Actually : "formed of glacial sediments deposited by meltwater outwash at the terminus of a glacier." Glacial slope varies.
  • edited January 2014
    @ArindamSarkar @Therock90

    Differences :-

    Soil:
    In alluvial soil is moist or damp or marshy in glacial plains it is not necessary general dry after glaciation

    Deposits:
    In alluvial plains there are hardly coarse (big) particles but silts deposits are huge in glacial plain we can find big boulders lying at regular intervals

    Topography:
    In alluvial plain it is almost flat but in glacial plains one can find drumlines & ground moraines surrounded by terminal morains

    Deposition rate:
    In alluvial plains fresh layers of soil/silt gets deposited depends upon precipitation and flood but in glacial it is more less stagnant.


    All criticism and appreciations are welcomed :P
  • @dp81

    Hi,

    Are you sure that soil in "Outwash Plains" will be dry...as it is the region where glacier is merging with the river.?
    So outwash deposits also contains some amount of fine silt which is carried by melted water.


    Also I didn't exactly understand your depositional rate point. Glacier also keep bringing deposits regularly i think.
  • @Therock90

    Bro jahaan glacier hota hai waha plains kaha hota hai ??

    Outwash plains to wahi hoga jahaan glaciation ho chuka hoga....
  • @dp81

    Yeah that's what i mean...but you said area would be generally dry...which I don't think is the case.

    are u sure soil will be dry?
  • @Therock90

    e.g. If aravalli range would have been subjected to glaciation in ice age do you think still it can have moisture of ice age
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