Notices
Results 1 to 7 of 7

Thread: Mountains and crust

  1. #1 Mountains and crust 
    Forum Freshman
    Join Date
    Nov 2008
    Posts
    87
    Hello there!


    Friction between lithosphere and asthenosphere is very weak, so the former can slide over the last one.
    But due to this very lack of friction, nothing prevents the possibility for the whole plates to glide at high speed (to human time-scale!), causing immediate destruction of the Earth's surface and what it contains.

    But as mountains have deep roots plunging into the asthenosphere,
    could they work as anchors for the plate IN ALL THEIR EXTEND by making that hypothetic dangerous movement impossible?


    Reply With Quote  
     

  2.  
     

  3. #2 Re: Mountains and crust 
    Universal Mind John Galt's Avatar
    Join Date
    Jul 2005
    Posts
    14,168
    Quote Originally Posted by termina
    But due to this very lack of friction, nothing prevents the possibility for the whole plates to glide at high speed (to human time-scale!), causing immediate destruction of the Earth's surface and what it contains.
    What do you mean by fast? There is no evidence that I am aware of that suggests this could occur at a rate likely to destroy the Earth's surface. Please me this isn't the HAB theory reincarnated. I don't believe in reincarnation or HAB theory, so the two in combination is anathema.
    Quote Originally Posted by termina
    But as mountains have deep roots plunging into the asthenosphere, could they work as anchors for the plate IN ALL THEIR EXTEND by making that hypothetic dangerous movement impossible?
    Since there is no danger of the hypothetical, rapid movement occuring, then the roots are incidental. Keep in mind also that delamination of the base of continental masses into the mantle is a likely process.
    Further keep in mind that the asthenosphere is within the mantle and below the roots of the continents.


    Reply With Quote  
     

  4. #3  
    Forum Freshman
    Join Date
    Nov 2008
    Posts
    87
    Further keep in mind that the asthenosphere is within the mantle and below the roots of the continents.
    i know that. But mountains crustal roots push down the lithospherci mantle which, in turn, locally depress the underlying asthenosphere.


    By 'fast', I mean a series of violent motion of 300km/h or even more, which would be enough to destroy Earth's surface.

    To suggest such possibility, there is the low friction between lithosphere (without mountains roots) and asthenosphere which would be (according to some) not high enough to hinder drastic gliding.
    Reply With Quote  
     

  5. #4  
    Time Lord Paleoichneum's Avatar
    Join Date
    Oct 2008
    Location
    Washington State, USA
    Posts
    5,294
    Quote Originally Posted by termina
    Further keep in mind that the asthenosphere is within the mantle and below the roots of the continents.
    i know that. But mountains crustal roots push down the lithospherci mantle which, in turn, locally depress the underlying asthenosphere.


    By 'fast', I mean a series of violent motion of 300km/h or even more, which would be enough to destroy Earth's surface.

    To suggest such possibility, there is the low friction between lithosphere (without mountains roots) and asthenosphere which would be (according to some) not high enough to hinder drastic gliding.
    What is your source for the 300km/h? this seems like a very questionable number.
    Reply With Quote  
     

  6. #5  
    Reptile Dysfunction drowsy turtle's Avatar
    Join Date
    Mar 2009
    Location
    UK
    Posts
    2,255
    You're right, there's not much in particular that would hinder the sudden movement of the continents should some massive force randomly cause them to start moving much more quickly.

    But what exactly might cause such a movement to start with? The force it would take to accelerate the continents to 300km/h very quickly would be huge, and that's if we ignore the resisting force of friction from magma and plastic rock - which by the way do still provide a lot of friction, just relatively less than at other places in the mantle/core.

    (Did you by any chance get this idea from the film '2012'?)
    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
    Reply With Quote  
     

  7. #6  
    Forum Freshman
    Join Date
    Nov 2008
    Posts
    87
    What is your source for the 300km/h? this seems like a very questionable number.
    This number is an example, because a member asked me what I mean by rapid movement.


    You're right, there's not much in particular that would hinder the sudden movement of the continents should some massive force randomly cause them to start moving much more quickly.
    even mountains roots couldn't make it impossible?


    But what exactly might cause such a movement to start with? The force it would take to accelerate the continents to 300km/h very quickly would be huge, and that's if we ignore the resisting force of friction from magma and plastic rock - which by the way do still provide a lot of friction, just relatively less than at other places in the mantle/core.
    well, i don't know excatly. The person making this hypotheisi claimed that such movement could have happened as the lithosphere floating on the asthenosphere is as free as an object on an ice rink soil.

    (Did you by any chance get this idea from the film '2012'?)
    No^^ This idea rather comes from the geologist Dr. Zanghul AL Naggar.
    Reply With Quote  
     

  8. #7  
    Reptile Dysfunction drowsy turtle's Avatar
    Join Date
    Mar 2009
    Location
    UK
    Posts
    2,255
    Quote Originally Posted by termina
    even mountains roots couldn't make it impossible?
    Not particularly. The main reason why this would never happen is there is never, realistically, going to be a force great anough to accelerate the continents to this sort of speed - especially since the force responsible will have to overcome the frictional force.

    Quote Originally Posted by termina
    well, i don't know excatly. The person making this hypotheisi claimed that such movement could have happened as the lithosphere floating on the asthenosphere is as free as an object on an ice rink soil.
    Yeah, that analogy doesn't really fit, because the whole surface of the ice rink is covered with flat objects. They might occasionally slip over/under one another, but they won't move around 'freely' with any great ease.
    "The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." ~ Douglas Adams
    Reply With Quote  
     

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •