Earths Expansion and Declining Seas

[AnnaG]

In this case very different pressures, the 1.000 magma just under the crust, the 7,000 deg magma is much deeper. The deeper you go in the mantle the higher the surrounding pressure is .

Mountain snow also stiffens up when an avalanche happens. BTW

Well then you are contradicting what you said in the first place that because it is liquid, the pressure is the same everywhere.

 

[MHz]

Sorry, but I don't think you've thought this through. You said there must be some pressure created by the gravity of the crust, which leads to volcanoes ( a very simplistic explanation by the way for volcanism). If the crust is still there, it's gravity is still there. The pressure can't reach zero in your hypothetical unless the crust disappears from your model entirely.

The crust is a shell, as such it can also support itself from the side. A stone archway only needs support during construction, once the mortar is hard the bracing can be taken away.

The mantel is losing heat by rubbing up against the crust and it should gradually have material stick and become part of the crust. Drop the average temp by 500 deg would the mass shrink enough to (want to ) leave a void next to the crust?

 

[Johnnny]

the mantle is losing heat because of radioactive decay and some other factors i thought, not because it rubbs against the crust. thats news to me

 

[MHz]

the mantle is losing heat because of radioactive decay and some other factors i thought, not because it rubbs against the crust. thats news to me

How silly of me to think granite can transfer heat. ???

 

[Tonington]

How silly of me to think granite can transfer heat. ???

Of course it can, but that doesn't mean that friction is the cause of heat loss. Touch a thermometer to your stove element. There is heat transfer, but it has nothing to do with friction.

 

[petros]

Psssst. We have a moon!

 

[MHz]

Of course it can, but that doesn't mean that friction is the cause of heat loss. Touch a thermometer to your stove element. There is heat transfer, but it has nothing to do with friction.

I didn't say anything about friction. When the magma rises as far as it can it flows along the bottom of the crust, transferring heat, that heat loss is what cools it off so it can take the trip back into the deeper reaches of the mantel where it gets heated and then it rises again. Here is another thing to muddle your mind. The mantel and the crust form a fairly smooth surface (ball) try putting a lighter element that is 25miles thick into it without it melting before you can slide it under the adjacent block of crust. At the rate finger-nails grow it would melt before you could get it under. Granite cannot make a 25 mile 'dip' in something that is twice as thick and above granite's melting point.

 

[AnnaG]

I didn't say anything about friction.

Friction is what the definition of "rubbing up against" describes (and I think you meant having contact with, not "rubbing up against" anyway):

The mantel is losing heat by rubbing up against the crust and it should gradually have material stick and become part of the crust.

- from your post number 147

Here is another thing to muddle your mind. The mantel and the crust form a fairly smooth surface (ball) try putting a lighter element that is 25miles thick into it without it melting before you can slide it under the adjacent block of crust. At the rate finger-nails grow it would melt before you could get it under. Granite cannot make a 25 mile 'dip' in something that is twice as thick and above granite's melting point.

Can you put that in legible English please.

 

[MHz]

Friction is what the definition of "rubbing up against" describes (and I think you meant having contact with, not "rubbing up against" anyway):
- from your post number 147 Can you put that in legible English please.

If it didn'y move side-ways (after making contact) I wouldn't have used rubbing, it isn't like those two sayings are polar opposites.

How about I put it in cooking terms instead. Remember that big pot of simmering portage that is at it's thickest. Say the crust was represented by two sticks of butter the same size and thickness as your hand. Imagine that the butter is on top of the portage and you are pushing the two pieces together to create a subduction zone. One end of one is lifted to represent mountains and the other is placed underneath to represent the subducting plate. One of two things is going to happen with that jagged edge, the mountain side is either going to get thicker or the sub-ducting side will get thinner. (also the magma has to be flowing in same direction as the sub-ducting plate and that heat would melt anything that was pushed into it, especially a sharp corner. Over time the jag would be smoothed out . The question: if the subducting plate is being shaved down some would that make it so weak that it could not push itself under and rather it breaks and folds, as in part of the Rockies being folded up like that.

Found this image after so you are suck with my previous typing. LOL the part hanging into the mantle is false, it would be melted befor it got that far and in it was to get that far down it would have to have twice that distance above because the material it is being pushed into is twice as dense.

tect3.html



Back to this planet and our West Coast which is promoted as being a subduction zone (and it is but not like it is promoted) The crust that is going under is how old? Hopefully your answer is in the millions of years because during that time it would have collected lits of space dust and fish poo. Where did all that stuff go, no way that material is going to slide under the weight of 25 miles of granite. There should be islands (very many and very large) on the other side of the actual crack, there isn't even one.
Wind back the clock on this picture. the crack is offshore these days but when it first started right under Vancouver Island.

 

[petros]

You need to be looking into the mafics and ultramafics at depth. Periodites and the likes.

P.S. We have a moon.

Moooooon.

Moon



Mooooooooooooooooooooooon

 

[MHz]

That a way too many new words for me at the moment,. Is that the same moon that shows no subduction even though the whole mantel tried to be called 'inbound' by the earth some time in the distant past. Catch her back-side in just the right light and you will find yourself saying 'prune face'

 

[petros]

The moon causes magmatic tides which creates a gosh awful lot of heat and keeps the planet from ever cooling to a solid.

 

[AnnaG]

If it didn'y move side-ways (after making contact) I wouldn't have used rubbing, it isn't like those two sayings are polar opposites.

:roll: Forget it. Try reading the definition of friction sometime.

How about I put it in cooking terms instead. Remember that big pot of simmering portage that is at it's thickest.

You lost me at the word "portage".

Main Entry: 1por·tage
Pronunciation: \ˈpȯr-tij, 3 is also pȯr-ˈtäzh\
Function: noun
Etymology: Middle English, from Anglo-French, from porter to carry
Date: 15th century
1 : the labor of carrying or transporting
2 archaic : the cost of carrying : porterage
3 a : the carrying of boats or goods overland from one body of water to another or around an obstacle (as a rapids) b : the route followed in making such a transfer

Merriam Webster


I got the pics. Those make sense.

The moon causes magmatic tides which creates a gosh awful lot of heat and keeps the planet from ever cooling to a solid.

Where does the non-frictional rubbing together come in there, though?

 

[MHz]

:roll: Forget it. Try reading the definition of friction sometime.

Like on a very slippery inclined hill? Good thing the brakes still work that will avoid having a big crash at the bottom of the hill where the train is crossing. That sort of friction?

 

[L Gilbert]

:roll: Forget it. Try reading the definition of friction sometime.

You lost me at the word "portage".
Merriam Webster

I think she meant porridge.

I got the pics. Those make sense.

Where does the non-frictional rubbing together come in there, though?

No sarcasm there, right? lol

Like on a very slippery inclined hill?

Huh? I don't think there's any such thing as an inclined hill.

Good thing the brakes still work that will avoid having a big crash at the bottom of the hill where the train is crossing.

So the hill wasn't slippery after all?

That sort of friction?

Friction: caused by two items rubbing together. You can't rub two things together without causing friction, so yes, you actually did mention friction in a fashion. And it isn't friction that causes the upper mantle to cool anyway. Friction cause heat buildup. Contact with cooler substances causes the cooling of the upper mantle. Contact ≠ friction although friction almost always requires contact.

 

[petros]

(shear force) = (force of gravity) x (sin (slope angle))

(normal force) = (force of gravity) x (cos (slope angle))

or something and then....



At the angle of repose:
Equation 4: (shear stress) = (cohesion) + (coefficient of friction) x (normal stress)

in cohesionless substances:
Equation 5: (shear stress) = (coefficient of friction) x (normal stress)

or restated:
Equation 6: (coefficient of friction) = (shear stress) / (normal stress)

The coefficient of friction is related to the friction between particles and depends on the characteristics of the material (e.g., is it rough or smooth, rounded or blocky):
Equation 7: (coefficient of friction) = tan (angle of internal friction)

and in the case of unconsolidated materials:
Equation 8: (angle of internal friction) = (angle of repose) = inverse tan ((shear stress) / (normal stress))

 

[Dexter Sinister]

Dex, your model says there is no expansion at the moment. There has to be some pressure created by the gravity of the crust that allows for the existence of volcanoes. At some point the pressure should become "0" and after the whole mantel cools it should begin to shrink, what happens to the crust. does it end up folding like the skin of a grape as it looses water from its core?

There isn't any expansion at the moment, and there never has been, the data simply do not sustain the expanding earth model. Your questions assume certain things that aren't true. Earth's internal heat comes mainly from residual heat left over from its formation and ongoing radioactive decay, mostly of uranium, thorium, and potassium. I don't know offhand what the relative contribution of each is. Volcanoes are not caused by the overpressure of the crust on the mantle, they occur in quite obvious patterns that are readily explained by the plate tectonics model. Shrinkage with cooling is not a factor in the size of the earth or its surface features. The coefficients of thermal expansion of most rocks are on the order of a few parts per million.

 

[AnnaG]

I think she meant porridge.

Ok that makes more sense, then.

No sarcasm there, right? lol

Who, me? :angel:

Huh? I don't think there's any such thing as an inclined hill.

lol Yeah, saying inclined hill is like saying horizontal level. lol

 

[MHz]

Volcanoes are not caused by the overpressure of the crust on the mantle, they occur in quite obvious patterns that are readily explained by the plate tectonics model.

If the moon was hot at one time and now it is cool that would apply to us also, just a longer time-line.

 

[petros]

Volcanoes are not caused by the overpressure of the crust on the mantle, they occur in quite obvious patterns that are readily explained by the plate tectonics model.

Mainly from subduction of waterlogged rock which makes for super heated gasses under extreme pressure which makes for dandy violent pyroclastic explosions more so than lava extrusives.

If the moon was hot at one time and now it is cool that would apply to us also, just a longer time-line.

The core grows from cooling at rate of about 1cm a year.