Interior of the Earth by Emilija Iannace 12/2/12

The Earth is not just a hollow sphere covered in rocks as you might have once imagined.  It turns out that the inside of the Earth is made of hot and dense solid and liquid materials.  The interior of the Earth consists of four main layers.  From the surface, the layers progress from the Crust, Mantle, Outer Core, and Inner core. As you go deeper into the Earth the heat, pressure, and density increases.  Each layer is hotter than the next so more pressure and density is added on from the layer above.




Of the Earth’s four layers, the mantle has the most diverse material.  The mantle consists of layers called the Lithosphere and the Asthenosphere.  The Lithosphere is a solid layer of brittle rock made up of the very upper mantle and the crust.  The Asthenosphere is in the mantle right below the Lithosphere.  Its rock is solid but able to flow, like tar, because it is a little bit lower in the mantle and is hotter.



The crust is the Earth’s outer layer of land and ocean floor, and it is the thinnest, coolest layer, averaging 32 km thick.  The crust consists of  granite continental crust and basaltic oceanic crust. Continental crust is thicker than oceanic crust, but the granite is less dense, while the oceanic crust is thinner, but the basalt is more vast and dense.



As we now know, the Earth’s lithosphere and asthenosphere are the two different layers in the mantle.  The lithosphere is a lot thinner than the asthenosphere, and is made of the crust and the top of the mantle, so the materials inside are rock.  The asthenosphere is thicker and softer (hotter), so the materials inside slowly flow.  Both layers have rock materials and are above the mantle.



The Earth’s mantle is the next layer below the crust, and it contains the lithosphere and the asthenosphere.  The mantle plays a big part in the Earth’s shifting plates because it creates convection currents in the asthenosphere from the core’s heat.  If the convection currents flow in opposite direction, the heat pries apart the crust and causes rifting and earthquakes.  If the currents flow towards each other the plates collide and build mountains.




The outer core is thicker than the inner core, and it is full of molten metal, while the inner core is full of solid metal.  The inner core is almost twice as hot as the outer core.  They are both made up of nickel and iron, and together, they create the center of the Earth.

The Earth’s outer core is responsible for creating Earth’s magnetic field.  The molten nickel and iron of the outer core rotates, and the movement creates magnetic and electric charges.  Imagine that the Earth has a giant bar magnet inside of it.  The magnetic field is connected from the North end of the magnet to the South end.  The size of the field changes, and sometimes the field reverses (North Pole becomes South Pole).  The Earth’s magnetic field extends thousands of kilometers  into space, creating a sort of magnetic bubble called the magnetosphere.

 

In class we looked at half a hard-boiled egg and half an orange that could be used to describe the Earth and its layers. Both were strong representations of the Earth’s interior, but some parts also had weaknesses.  The hard-boiled egg had a thick, solid shell like the Earth’s crust.  The egg white made an accurate mantle, and the yolk was a good imitation of the whole core.  The only problem with the hard-boiled egg model was that it had an oval shape, unlike the round Earth.  Also, the whole core was solid, instead of the outer core being liquid with a solid inner core.  

The orange half had all of the layers, with an accurate crust, mantle and core.  The orange’s juicy flesh part showed a liquid core and a solid inner core.  The weaknesses of the orange half were that the outer core was too big and the inner core was too small.