Ask a guru a question

don findlay wrote:
WillE1 wrote:
"don findlay" wrote in message
oups.com...
Don Findlay has a link on his website about Plate Tectonics saying to
"ask a guru a question" - down the bottom of his page
http://users.indigo.net.au/don/ee/abstract.html
Does anybody have any idea of a reasonable question I could ask about
plate tectonics? Does plate Tectonics have any questions? Or only
answers? And if it's only got answers, what's the biggest one?


Where are the nearest hot springs from here? It has been ages since I've
been in one. Time for me to take a break. While I am sitting in the
geothermal pool I promise to think about your question Don. And when I get
back, I'll have a few questions for you. Will E.

Right, Will, .. Just don't fall asleep in the pool, will you.... You
are our only hope to test these gurusome badunkabadunks.

Here's one to be going on with, ...for anybody to answer (..reveal me
for the ignoramus I am increasingly finding myself to be) ...I can't
remember ever coming across any allusion to the problem this 'cold
descending slab' (the one Mr Uyeda says is being pushed down by the
continental side of the equation) (and for which that other fellow got
a prize for helping him say so) confronts when it meets the higher
temperature regime it's going down into. Why doesn't the heat down
there make it pop back up where it came from? (Like it does at the
other end of the cycle - drives everything up) Because the continents
are pushing it down? ..pushing it through the eclogite transition and
making it dense so it sinks? Denser than what? Denser than the basalt
etc it used to be? Or the eclogite already down there??

We've been through the bit about the continents pushing the shubducting
slab down before, ..so this is just about the next bit of nonsense,
..the failure of heat-source at this end of the cycle to push
everything back up.

Blobtonics always worth a google-up for a laugh
..and ambient rise of the mantle when the slab goes down is an even
better one...

Or what about this one, under the "more stories" banner:-
--------------------------------------------------------------------------------
"Suction and pull drive movement of Earth's plates, U-M researchers
show.."
( http://www.umich.edu/~urecord/0203/O..._suction.shtml )
(Can anybody maybe find a few questions hiding in here? )

"When two plates collide, one is forced beneath the other into the
mantle .... creating what geologists call a subduction zone. Because
subducting slabs are colder and more dense than surrounding mantle
material, they tend to sink like a lead ball in a vat of molasses.
... "It's been known that slabs (portions of plates that extend
down into the Earth) drive convection in Earth's mantle, and
ultimately the motion of the surface plates, but it hasn't been well
established exactly how that happens-the ideas have been fairly
vague," says Clinton Conrad, a postdoctoral fellow in the department
of geological sciences.

"There are two main ways these sinking slabs might influence plate
motion. If a slab is attached to a plate, the slab can directly pull
the plate toward the subduction zone. A slab that is not well attached
to a plate, on the other hand, can't pull directly on the plate.
Instead, as it sinks, it sets up circulation patterns in the mantle
that exert a sort of suction force, drawing nearby plates toward the
subduction zone much as floating toys are drawn toward the outlet of a
draining bathtub.

"To understand the relative importance of slab pull and slab suction
forces, Conrad and Carolina Lithgow-Bertelloni, an assistant professor
of geological sciences with whom he worked on the project, developed
models in which: 1) only slab suction was operating; 2) only slab pull
was operating; and 3) both slab suction and slab pull were at work.
Then they compared the plate motions that would result from each of
these scenarios with actual plate motions. The best fit was the model
that combined slab pull and slab suction forces.

"The model also explained an observation that has baffled
geodynamicists for some time. "The way the observation was originally
framed was that plates that have continents on them are slow, compared
to plates that are only oceanic," says Lithgow-Bertelloni.

But the real issue is whether or not the plates have slabs attached,
she says. Overriding plates, which have no slabs, are slower than
subducting plates, which have slabs. The explanation? Subducting plates
move faster because the pull effect acts directly on them, making them
move rapidly toward the subduction zone. Overriding plates are also
drawn toward the subduction zone-by the suction effect-but at the
same time, the pull effect creates forces in the mantle that counteract
that motion. The net effect is that overriding plates move more slowly
toward the subduction zone than subducting plates do.

"We've been able to explain that the difference in speed occurs
because slab pull generates mantle flow that counteracts the motion of
the overriding plate," says Lithgow-Bertelloni. "We also found that
this effect is only important for slabs in the upper 600 to 700
kilometers of the mantle. Any slabs deeper than 700 kilometers do not
contribute to this effect. They're important for driving flow in the
mantle, but they're not important for the pull."

Ground breaking stuff from umich
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http://tinyurl.com/yzbsqw
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Hey, .. I wonder if Stunami Sue will chip in that bit about 'mantle
wind'...coming through 'trapdoors', ... Maybe after the break... I
mean, ..are we supposed to think this rubbish actually has currency,
...and Plate Tectonics has a 'mechanism' of sorts? (That's the question
for a guru, that is increasingly on everyone's lips...)

-----------------------------------------------
**The Story of Plate Tectonics**

The story of Plate Tectonics is a fascinating story of continents
drifting majestically from place to place breaking apart, colliding,
and grinding against each other; of terrestrial mountain ranges rising
up like rumples in rugs being pushed together; of oceans opening and
closing and undersea mountain chains girdling the planet like seams on
a baseball; of violent earthquakes and fiery volcanoes. Plate Tectonics
describes the intricate design of a complex, living planet in a state
of dynamic flux.
http://www.platetectonics.com/
------------------------------------------------

This would be a joke if it were not for the tacit support of
universities worldwide, and the billions of dollars that have been, and
still are, getting spent on it. And to what end? the load of hogwash
you can read on any of the (now) how many million sites (?) on Plate
Tectonics - being taught in our schools? Don't you reckon we deserve
a better deal from our so-called 'professionals'?

And what's the question academics are intent on addressing? Do plates
have slabs attached?
Check out ' blobtonics'