Re: Tectonic plates and seams

After a few years of talking about nothing it is good to see you
attempt to discuss your stationary Earth notion of convection
cells .After announcing publically that you have these childish
'killfiles'it should seem stupid to everyone else that you know so
much of what I propose.If you are too dumb to know that publically
announcing a killfile works against the the original intent of such a
statement in the long run ,you can suffer be the poster boy for how
people who like to keep their Earth stationary,a variation on
creationism if you like (except they recognise a moving Earth).

On Feb 28, 2:31 pm, Aidan Karley <name1_na...@xxxxxxxxxxxxxxxxxxxxxx>
wrote:
In article <ae7f4d40-e2ef-4765-aebb-182e1436e...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>, Brad wrote:
at my local magazine retailer i found this article in march/april
issue of American Scientist

       Ah, useful to know that it's out. A much better investment of $8
than Scientific American (though that's less a waste of trees than an
awful lot of other dross on the shelves. I'll maybe take a look down at
the university campus newsagent after I've finished baking today's loaf.

what i found interesting (at least in terms of
recent discussions ) is the reconstruction of Gondwana - at the S
pole !

       Pretty standard. Has been pretty much like that for 2 decades,
maybe three.

this means that the spreading centers that formed and broke up
the continent originated near the pole and raises doubts about any
rotational dynamics playing a role in PT .

       Ah, you've been listening to oriel36 ? Well, it'll be amusing to
see what his response to someone doubting him is.
       The speed of latitudinal change in plate tectonic reconstructions
is low enough that anyone with an ounce of mathematical ability would
realise that the forces produced are going to be totally negligible
compared to the ridge-push and slab-pull forces, the basal drags and the
inertial forces. Again, this is not news to conventional geology, but
totally shocking to oriel35.


Thermally driven convection cells in other words,which leaves you
having to explain how the shape of the planet is derived in a
meaningful way.

A reasonable person could probably look at the motion of a rotating
celestial object with a flexible/moilten composition and gauge that
the correlation between speed at the Equatorial and the differential
rotation towards the poles and stellar dynamicists already do this as
a matter of course -

http://www.youtube.com/watch?v=7dfKoPsA8KQ

If you are hung up on the rotational dynamics of a flexible/molten
planetary interior with the exposed rotational plasma of a star then
you probably miss the point,you may be unique among the few here who
will openly support 'convection cells' and fair dues to you.



and further implies that
convection cells don't need rotational patterns at all to do work .

       Much the same commentary.

are rotational forces responsible for their present configuration? the
past migrations of the cratons would seem to belie that and

       The early formulations of plate tectonics had the "hotspots" as a
fixed framework, probably anchored on compositional features at the
core-mantle boundary. However more detailed work has shown fairly
conclusively that the hotspots do move, though relatively slowly and not
clearly related to the pattern of plate movements, ridges and
subduction. The forces involved in those movements dwarf Coriolis-type
forces arising from the rotation of the Earth.

The rotational dynamics in the Earth's interior are uni-directional
which is why ocean crust creation not only roughly follows rotational
orientation but also in proportion to rotational speeds.I do not even
have to appeal to surface geometry for most people already know that
spherical deviation is a feature is of rotational dynamics and no
point in making the Earth interior exempt from the already known and
observed differential rotation mechanism.




       Plus, of course, the present arrangement of the plates (and
therefore of the ascending and descending plums of convection cells), is
quite temporary.

the
past migrations of the cratons would seem to belie that and  the fact
that we see them N-S now would

       So, the Scandanavian craton, Russian shield, Siberian craton and
Laurentide craton are arranged north-south. Hmmm, I must check my
compass.

       Rotation of the Earth isn't considered important in tectonics. At
least, not by geologists.


I hope genuine geologists get sick when they here that
pronouncement,you have just limited yourself to a geostationary view
when recently dynamicists have started to study correlations between
rotating objects of roughly the same size ,composition and viscosity
with deviations from spherical geometry.The fact that the profile of
the crust crosses the less than spherical Earth makes it almost
certain that surface features do arise from rotational dynamics,even
without refering directly to the mechanism

You have the same problem as the EE guys,you have established
convection as a 'fact' and organised the Earth's interior to suit that
conclusion.You are content with that conceptual dead end and that is
all that matters,I still have to wait for somebody who actually likes
a rotating Earth,that is all.




--
Aidan Karley, FGS,
Aberdeen, Scotland

.

Relevant Pages

  • Re: Tectonic plates and seams
    ... rotational dynamics playing a role in PT. ... Thermally driven convection cells in other words,which leaves you ... forces arising from the rotation of the Earth. ...
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