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Thread: magnetite and the magnetic fields

  1. #1 magnetite and the magnetic fields 
    Forum Ph.D.
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    i know magnetite was used to prove that the continents moved, but i'm not sure how this connection was made?


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  3. #2  
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    Wasn't this discovered at the mid-ocean ridge? where in its molten form it it set with it's magnetic field aligned to the Earth's pole. As this flipped from time to time causing stripe variations, the only theory to satisfy this was continental drift and the mag field reversals.


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  4. #3  
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    Yes, and also portions of some continents "match" portions of other continents better than they match their current continent. The magnetic stratigraphy of the east coast of north america is evidently more similar to Africa than to other portions of North America. Thus North America and Africa were once connected.

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    Forum Professor sunshinewarrior's Avatar
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    Love the graphic!

    Do you know if there's a web-based resource that contains a time-sequenced set of maps regarding the break-up of Pangaea and all the rest of it?

    I keep reading about geological periods and comparing them to evolutionary events but it seems to me a set of maps would be really helpful and none of the books I've read seems to have a comprehensive set. Most simply do a before and after - one pic of Pangaea and one of the modern land-mass outlines.
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  7. #6  
    Forum Ph.D.
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    yeah paleomap is great!
    they even have interactive versions of the maps.
    when you have eliminated the impossible, whatever remains, however improbable, must be the truth
    A.C Doyle
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    Forum Professor sunshinewarrior's Avatar
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    Ta. I've bookmarked it. :P
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  9. #8  
    WYSIWYG Moderator marnixR's Avatar
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    there's another way that magnetism has been used to show that continents have moved : a magnetic sample has a certain angle versus the horizontal depending on the latitude where it was formed

    near the equator this angle is horizontal, the closer one gets to one of the poles the steeper the angle becomes (presumably reflecting the angle of the magnetic field at that latitude)

    analysis of magnetic samples in one position over time showed a change in angle and hence a change in latitude
    "Reality is that which, when you stop believing in it, doesn't go away." (Philip K. Dick)
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  10. #9  
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    Quote Originally Posted by marnixR
    there's another way that magnetism has been used to show that continents have moved : a magnetic sample has a certain angle versus the horizontal depending on the latitude where it was formed

    near the equator this angle is horizontal, the closer one gets to one of the poles the steeper the angle becomes (presumably reflecting the angle of the magnetic field at that latitude)

    analysis of magnetic samples in one position over time showed a change in angle and hence a change in latitude
    A very good point, the magnetic dipoles will be aligned along 3 axis, so by going back through them you can create a 'reverse video' of the way things moved.
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  11. #10  
    The Doctor Quantime's Avatar
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    Nice to know the UK won't be morphed for a while. Long live Brittania!
    "If you wish to make an apple pie from scratch, you must first invent the universe". - Carl Sagan
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