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Masis

Senior Member
Bulgarian
In between , marking the farthest advance of the glaciers, lay deposits that created the dreinage divide along the line Grodno - Minsk- Smolensk - Valdai Hills.


Hello. Please help me with this word here. I can not udnerstand whether it means here alluvium ( wash, drift ) or this is something else. Thanks a lot.
 
  • MichaelW

    Senior Member
    English (British)
    I'm not a geologist but "alluvium" refers to deposits left by rivers (that is, by running water).

    I would have thought that the deposits would be soils, rocks, boulders etcetera pushed into place by the glaciers, not alluvium.

    For instance

    "all glacial deposits are called "glacial drift" and are comprised of two types--1. non-stratified drift called "till" which is non sorted, meaning comprised of many different particle sizes (see Wentworth's scale of sedimentary particles)--2. stratified drift called "outwash" which is sorted, meaning comprised of essentially the same size particle which results in stratification."

    from this page here.
     

    Masis

    Senior Member
    Bulgarian
    Thanks. I think so too. That alluvium is for rivers. So this are something different. I have an idea but I can not explain in English unfortunately. I hope that I am right. But from glaciers are formed many loess depositions. And in Bulgarian loess is described as alluvium. So from glaciers can form alluvium just like from river. The term is the same but the object is different.
     
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    MichaelW

    Senior Member
    English (British)
    I thought loess is either a wind-blown sediment - from Wiki

    "Loess is an aeolian sediment which forms by the accumulation of wind-blown silt"

    or glacial

    "Glacial loess is derived from either glacial or glacial outwash deposits"

    so I'm surprised that it could be described as "alluvial", which to me is definitely only something deposited by rivers etcetera.
     
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    Masis

    Senior Member
    Bulgarian
    But I read that loess is formed by actions of glacierd. Maybe ot forms from combined action of all of this.
     

    GreenWhiteBlue

    Senior Member
    USA - English
    As it so happens I live on a terminal moraine that marks the furthest extent of a glacier. The hill on which I live is deposit from the retreat of the last glacier.

    A "deposit" is something that has been "deposited": that is, it has been carried somewhere and then left there. A glacier pushes soil and rocks in front of it, and when the glacier melts, that material (which has been deposited by the glacier; in other words, those deposits left by the glacier) can form lines of hills. Water runs down the sides of hills, and so with this line of hills, the water on one side will run in one direction, but the water on the other side will run in another direction because the hills are in the way. The glacial deposit (that is, the hills) therefore serves as a divide to the drainage of water: that is, the drainage divide is created by deposits from the last glacier.
     
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