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Discussion in 'Earth Science' started by sculptor, Sep 16, 2020.

  1. sculptor Valued Senior Member

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    Write4U, DaveC426913 and sideshowbob like this.
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  3. sculptor Valued Senior Member

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    continental drift
    are the continents being pushed by the midocean ridges
    or
    are the continents being dragged into the deep trenches by gravity
    (much like covers falling off a bed)
    or
    both ?
    .........................
    North America(where I live) seems to have been pulled apart at least twice in the last 400 million years
    The last time (@50 million years ago)it seems to have left a series of fault zones up the Mississippi valley
    and then, North America seems to have been pushed back together again by the spreading Atlantic sea floor?
    These movements have torn fragments off the appalacians leaving one in texas, and another in missouri.

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    While in the Basin and Range of the western US, the crust has been stretched by up to 100% of its original width. As a result of this extension, the average crustal thickness of the Basin and Range region is 30 - 35 kilometers (19 - 22 miles), compared to a worldwide average of around 40 kilometers (25 miles).
    Indicating the continent being pulled into the deep trenches along the pacific shore
    so
    Both?
    At different times?
    or by varying degrees over time?
     
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