Why does the earth's crust not melt into the mantle?

Question

Why does the earth's crust not melt into the mantle?

Answer 1

The crust temperature is balanced by under heat and top cooling.

Answer 2

Crust sitting on top of  the mantle does not melt b/c the mantle itself is not molten.  Shallow mantle is brittle rock but as you get very deep it starts to be more elastic (behaving more like a liquid).  But only in certain places (ex. mantle plumes) does it actually become molten in the sense that the rock actually becomes magma.

Answer 3

Maybe you're thinking of the outer core, which is molten.  The mantle is not molten in most places.

Basically, the crust and mantle do not melt into the core because the heat from the core is balanced by the cold of space.  The heat from the core rises up into the mantle and the crust, and then radiates into space. The crust is a very good insulator, so the heat moves very slowly.  This gives the crust a lot of time to radiate the heat into space.

Answer 4

this is a great question! my guess is that is has something to do with the polar ice caps, and the oceans, they have enough of a cooling effect to keep the crust cooler than the magma.-blurey

Answer 5

The mantle isn't hot enough to melt it.  It isn't molten itself except in certain hot spots.  Even there the heat isn't enough to do more than cause volcanoes.

Answer 6

The crust is much less dense than the mantle but even so some melting must occur although its not yet known to science. The reason the Pangaea land mass split in the middle forming the Atlantic ocean must have been because the crust in th middle of Pangaea melted somewhat and got weak. Or so it seems to me anyway,but I'm open to a better idea.

Answer 7

The crust is made of slightly different rock than the mantle. The mantle flows very slowly in a hot plastic sort of way. The crust will move in an explosive way (earthquakes, volcanos, etc.) The thickness of the crust provides insulation between the top and bottom of the crust, so that the bottom of the crust can get close to 2000F while the top is substantially less. Without getting in too much detail, the crust actually does melt into the crust at certain boundary lines around the globe. But lucky for us, it take a very long time.