Why Earth's mantle is solid

Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure.

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up, except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Freezing from the bottom up is a much faster process than freezing
from the top down, as the heat flux from below continues to decrease
(yes, there is convection, but the effective viscosity is much higher
in a solid than a liquid), and therefore should go to completion.

Andrew Usher

Andrew Usher wrote:

Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure.

Bull****. Silicon, bismuth, clathrates... have denser liquids than
solids. Ditto silicate melts vs. zeolites. Metal-organic
frameworks. It's a trivial thing to do given crystal structure.

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up,

Since it can only cool from the top down you might want to rethink
that. Hawaii is frozen at the top and liquid at the base.

except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Freezing from the bottom up is a much faster process than freezing
from the top down, as the heat flux from below continues to decrease
(yes, there is convection, but the effective viscosity is much higher
in a solid than a liquid), and therefore should go to completion.

So sad.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2

On Sep 4, 4:51 pm, Uncle Al wrote:
Andrew Usher wrote:

Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure.

Bull****. Silicon, bismuth, clathrates... have denser liquids than
solids. Ditto silicate melts vs. zeolites. Metal-organic
frameworks. It's a trivial thing to do given crystal structure.

Silicon and bismuth are the semi-metals I was thinking of, along with
Ge, Sb, As, graphite. I consider clathrates a type of water ice.
Zeolites
are not equilibrium phases and can't coexist with a melt.

Saying it's 'trivial' is pointless; of course it's a function of
crystal
structure.

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up,

Since it can only cool from the top down you might want to rethink
that.

So? Convection is faster than heat loss in a liquid.

Hawaii is frozen at the top and liquid at the base.

Hawaii, like all volcanoes, has liquid under it but that's only
possible locally as the magma is less dense than the surrounding
rock. This is simply hydrostatic equilibrium.

except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Freezing from the bottom up is a much faster process than freezing
from the top down, as the heat flux from below continues to decrease
(yes, there is convection, but the effective viscosity is much higher
in a solid than a liquid), and therefore should go to completion.

So sad.

I don't think you're really this stupid.

Andrew Usher

"Andrew Usher" wrote in message
...
On Sep 4, 4:51 pm, Uncle Al wrote:
Andrew Usher wrote:

Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure.

Bull****. Silicon, bismuth, clathrates... have denser liquids than
solids. Ditto silicate melts vs. zeolites. Metal-organic
frameworks. It's a trivial thing to do given crystal structure.

Silicon and bismuth are the semi-metals I was thinking of, along with
Ge, Sb, As, graphite. I consider clathrates a type of water ice.
Zeolites
are not equilibrium phases and can't coexist with a melt.

Saying it's 'trivial' is pointless; of course it's a function of
crystal
structure.

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up,

Since it can only cool from the top down you might want to rethink
that.

So? Convection is faster than heat loss in a liquid.

Hawaii is frozen at the top and liquid at the base.

Hawaii, like all volcanoes, has liquid under it but that's only
possible locally as the magma is less dense than the surrounding
rock. This is simply hydrostatic equilibrium.

except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Freezing from the bottom up is a much faster process than freezing
from the top down, as the heat flux from below continues to decrease
(yes, there is convection, but the effective viscosity is much higher
in a solid than a liquid), and therefore should go to completion.

So sad.

I don't think you're really this stupid.

Andrew Usher

The "I don't think you're really this stupid" statement is an example of a
conditional variation on argumentum ad homenim. Statistically, I don't need
to see the rest of the thesis to be fairly certain that the author of that
statement has insufficient supporting facts - so if I'm pressed for time and
I catch you making a false argument, I'll just assume you're in error and
move on. Here's why:

The verity of a conclusion may well be independent of the supporting
argument's fallaciousness, but nearly all of the times when people resort to
fallacy, they generally only do so when there is a glaring lack of
supporting evidence. Do a bit of reading (actually, quite a bit of reading!)
and you too will discover that the fallacy is only very rarely used in
association with an otherwise genuinely valid thesis.

Try again...

--
Timothy Casey GPEMC! Conditions apply. See www.fieldcraft.biz/GPEMC
Essays: http://timothycasey.info; http://speed-reading-comprehension.com
Softwa http://fieldcraft.biz; Scientific IQ Test, Web Menus, Security.
Science & Technical: http://geologist-1011.com; http://web-design-1011.com

On Sep 5, 9:45 pm, "Number Eleven - GPEMC!"
wrote:

Freezing from the bottom up is a much faster process than freezing
from the top down, as the heat flux from below continues to decrease
(yes, there is convection, but the effective viscosity is much higher
in a solid than a liquid), and therefore should go to completion.

So sad.

I don't think you're really this stupid.

Andrew Usher

The "I don't think you're really this stupid" statement is an example of a
conditional variation on argumentum ad homenim.

What do you think his 'So sad' was?

Andrew Usher

"Andrew Usher" wrote in message
...
On Sep 5, 9:45 pm, "Number Eleven - GPEMC!"
wrote:

Freezing from the bottom up is a much faster process than freezing
from the top down, as the heat flux from below continues to
decrease
(yes, there is convection, but the effective viscosity is much
higher
in a solid than a liquid), and therefore should go to completion.

So sad.

I don't think you're really this stupid.

Andrew Usher

The "I don't think you're really this stupid" statement is an example of
a
conditional variation on argumentum ad homenim.

What do you think his 'So sad' was?

Andrew Usher

There is enough ambiguity in the "so sad" statement to equivocate the point,
although in most cases it would be equivocal ad homenim. For example, the
use of deduction (argument from general principle) on points of complex
systems where the correct mode of argument is inductive (argument from fact)
tends to oversimplify the complexity of real systems to a point that is
quite literally depressing - hence "so sad". I'm not making excuses for
Uncle Al, but rather the point that this does fall to intent; and not being
a mind reader, I found your statement's lack of ambiguity definitely merited
my comment.

I can understand your feeling singled out here and the same points I made
may well apply to the "So sad" statement to which you were responding.
However, repeating the mistakes of others rarely if ever fixes the problem.
In this case returning ad homenim for ad homenim only ever starts a never
ending cycle that can be unfailingly observed in the conduct of Australian
politicians during "Question Time" in Parliament.

Solidification is a complex process and demands an inductive approach. It
would be worth looking into the difference between the behaviour of crystal
lattices such as those found in minerals such as graphite, mica and quartz
and that of liquids such as room temperature water - liquids are prone to be
amorphous even when the viscosity is too high to watch the flow occur in a
human life span. Then you have fluids as separate from homogenous liquids
which, whether gaseous or aqueous, are normally a composite of solid liquid
and/or gaseous material with sufficient liquid or gas phase present to flow
(Eg. nue ardente, clouds, turbidites, and many lavas, etc.). If the mantle
wasn't a fluid, isostatic rebound would not be possible and sea level would
have followed temperature throughout the Phanerozoic. Sea level is
demonstrated by Phanerozoic earth history to be at least partly independent
of temperature. See the main diagram at:
http://climate.geologist-1011.net
The diagram is properly paginated and the site has a print layout so you can
actually print just the chart by setting the "Pages from" 4 "to" 4 option on
the print form (window) - if that makes it any easier to read.

However, cutting to the chase, may I suggest reading up on how seismic
evaluation is used to determine phase boundaries. I'd recommend:

Press, F. & Siever, R., 1982, Earth, Freeman & Co., ISBN: 0-7167-1362-4.
Milsom, J., 1989, "Field Geophysics", ISBNs: 0-335-15207-4/0-470-21156-3.

Press & Siever (1982) is a good all round introduction and well referenced
so you can work your way into the literature on your topic of interest.
Press & Siever (1982, p. 410) explains that P waves propagate through both
solid and liquid phases while "S waves cannot travel in a liquid". This
means that by observing the propagation and degradation of different wave
forms over time and distance, you can determine quite accurately where
solid/liquid boundaries and phases are located. Milsom (1989) addresses some
of the practical aspects in more detail with respect to remote sensing
methods such as seismic and stratigraphic modelling.

You see, isn't that so much better than just telling someone to "Learn
something before posting."
)?

Once again, why attack the person if you can just put your point forward,
unless you don't have a point to begin with...?

--
Timothy Casey GPEMC! Conditions apply. See www.fieldcraft.biz/GPEMC
Essays: http://timothycasey.info; http://speed-reading-comprehension.com
Softwa http://fieldcraft.biz; Scientific IQ Test, Web Menus, Security.
Science & Technical: http://geologist-1011.com; http://web-design-1011.com

Andrew Usher wrote:
Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure.

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up, except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Is the crust really all that different material from the mantle? In the
early days, I just thought the crust was just cooled mantle material.
How do they really know what the mantle is made of?

Anyways, what's the liquid (i.e. magma) that exists below the crust made
of? Is it liquefied crust, or liquefied mantle? If it's liquefied crust,
then isn't that another example of a liquid existing below its solid phase?

Yousuf Khan

On Sep 5, 12:08 am, Yousuf Khan wrote:
Andrew Usher wrote:
Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure.

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up, except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Is the crust really all that different material from the mantle? In the
early days, I just thought the crust was just cooled mantle material.
How do they really know what the mantle is made of?

The crust is differentiated from the mantle, oceanic crust less so
than continental. We know the composition of the mantle, I think,
largely from astronomical abundances.

Anyways, what's the liquid (i.e. magma) that exists below the crust made
of? Is it liquefied crust, or liquefied mantle? If it's liquefied crust,
then isn't that another example of a liquid existing below its solid phase?

Magma is formed by partial melting of either mantle or crust. Yes, it
is
less dense than surrounding rock, which is why it moves upward.

Andrew Usher

On Sep 5, 6:13*pm, Andrew Usher wrote:
On Sep 5, 12:08 am, Yousuf Khan wrote:

Andrew Usher wrote:
Every solid save water ice and a few semi-metals is denser than the
liquid of the same composition, and the same temperature and pressure..

This means that a liquid other than water will not exist beneath a
solid of the same composition in a planet. A magma ocean therefore can
only freeze from the bottom up, except for the granitic crust which,
owing to its composition, is lighter than the liquid mantle. The
amount of granitic crust which could exsolve is pretty high, if the
mean composition is that of albite perhaps 20% of the mantle in the
extreme - but this would not be reached until far below the solidus.

Is the crust really all that different material from the mantle? In the
early days, I just thought the crust was just cooled mantle material.
How do they really know what the mantle is made of?

The crust is differentiated from the mantle, oceanic crust less so
than continental. We know the composition of the mantle, I think,
largely from astronomical abundances.

Anyways, what's the liquid (i.e. magma) that exists below the crust made
of? Is it liquefied crust, or liquefied mantle? If it's liquefied crust,
then isn't that another example of a liquid existing below its solid phase?

Magma is formed by partial melting of either mantle or crust. Yes, it
is
less dense than surrounding rock, which is why it moves upward.

Andrew Usher

My guess is that you have no idea of what the mantle is. Am I close to
being correct?

My second guess is that you've never completed a college course in
geology, or even own a textbook on the subject.

Am I close again?

Seriously, the dyanics of the earth's interior are likely much more
complex than a layman might assume.

Just for the record, the mantle is an interface point upon which the
less denser continental masses float. The interior of the earth is
generally considered to be a totally molten mass of mixed heavy
metals, starting with iron and going through uranium and possibly even
heavier elements.

Physicist and geologist tend to disagree on the reason why the core of
the earth remains liquid, or ever if it is liquid. Actually, finding
out exatly what is going on in the earth's interior remain today
unknown.

Harry C,

On Sep 5, 5:37 pm, " wrote:

Physicist and geologist tend to disagree on the reason why the core of
the earth remains liquid, or ever if it is liquid. Actually, finding
out exatly what is going on in the earth's interior remain today
unknown.

The Earth's interior is far from unknown. Learn something
before posting.

Andrew Usher