How come in the layers of the earth, they come in alternate liquid and solid?

Question

How come in the layers of the earth, they come in alternate liquid and solid?

Answer 1

There are really only two areas of appreciable liquid, the surface of the earth has liquid water- the hydrosphere and then the outer core (1800- 3000 miles down) is thought to be a mixture of liquid iron and nickle. What other "layers" are you thinking of? The asthenosphere (60- 150 miles down) is the ultimate source of all magma and it only is about 10% molten. The rest of the earth is solid, even the mantle!

Answer 2

BECAUSE OF THE DEPTH AND PRESSURE IT CAUSES HIGH TEMPERATURES

(sorry for the caps)

i belive the reason the core is solid is mainly because its composed of mostly nickel and iron (compression is another factor tho)

Answer 3

When all the elements that formed the earth were initially massed together, they formed a molten mass orbiting the sun. It is easy to imagine that the outer layer lost heat by radiation directly into outer space, as still happens to-day.

the heaviest elements, especially iron, sank through the molten mass due to gravity, and a solid iron core was developed. even at the elevated temperatures that the core must be, it has the whole world pressing down on it and this pressure makes the iron act as a solid. Note, although iron did sink, not all the iron sank, otherwise we would not be able to have iron ore mines at surface.

There is a molten zone between these two. It gradually loses heat, but the already cooled outer crust forms a sort of blanket around it, keeping much of the heat in.

Don't forget the oceans. they are liquid, too. Water forms a natural part of the earth's crust, and is called ice when frozen.

Ice is a natural mineral, rock of the earth as well.

The atmosphere is a gas mixture, but still very much a natural part of our wonderful planet.

It is very simple to appreciate the layered structure of the earth, isn't it?

Answer 4

It has to do with the temperature as you get lower towards the earth's core, for one thing.  The lower you go, the hotter it gets, and at a certain point, like everything else, rock, with enough heat, turns to molten rock.

Pressure also has a say in what 'phase' (liquid, solid, gas) anything can be in.  Try looking up 'phase diagrams' to get an idea of how it works.  

So, according to our friend, Wikipedia, the inner core of the earth is solid, the outer core liquid, and the mantle (above) solid.  This is because:  the more pressure you exert on a substance, the more likely it is to become a solid (except water....water's an outlier).  

Temperature AND pressure increase as you dig deeper into the earth, so you get a banding effect as each plays its part on the solidification / liquifaction of the rock.

Answer 5

It doesn't, really.  But you do get zones of partial melting, where there can be coexisting liquid and solid (a slush) over a large range.

The reason is relatively complicated, but generally related to the non-linear behavior of the interior of the earth in P-T space (pressure and temperature do not change at the same rates with change in depth).  

Effectively, the earth in in the process of segregation of its materials to zones of stabilty.  Solids tend to "sink" and liquids tend to "rise".    It is a dynamic situation, hasn't gone to completion, so you get zones where the process is still occurring, zones of liquid mixed in with solid, still trying to separate.  And things get pushed from areas where they are stable to areas where they can become unstable, keeping the whole mix in motion.

And add to it all the fact that the temperature gradient is not static, does not stay constant, but is slowly become less.  

Ultimately, the earth will become a solid with only a small temperature gradient as the heat from radioactive decay inside the earth becomes inadequate to maintain or produce zones of melting.  Think of the condition of the moon (solid through and through) as where the earth is heading.