At the very center of the Earth is a white-hot core of solid iron and nickel. It is hot enough for the metals to melt into a liquid, but they stay solid because they are squeezed together by the weight of rock on top. The outer core is made of iron and nickel with some oxygen and sulfur. It is so hot that they melt into liquid. Because Earth is constantly spinning around, the liquids in the outer core move and flow like ocean currents. The crust is made up of giant rocky plates, which move around incredibly slowly.
Where two plates grind together, one sometimes gets pushed under the other. The place where two plates meet is called a fault line. Earth is surrounded by a layer of gases called the atmosphere. Geologists have confirmed that the outer core is liquid due to seismic surveys of Earth's interior.
The outer core is 2, km thick and goes down to approximately 3, km into the earth. When Earth was just beginning to cool billions of years ago, heavier elements sunk down into the center of the Earth, while less dense elements rose to the surface.
Therefore, we see a general increase in density, as you get closer to the center of the Earth. The outer core is hot enough to be melted but not under quite enough pressure to make the iron solid again, as seen in the inner core. The temperature of the outer core ranges from about 4, to 5, degrees Celsius. Amazingly, the outer core is fluid enough and low enough in viscosity that it may spins faster than the entire Earth.
This differential velocity of spinning, along with convection and turbulent flow of the iron outer core, creates Earth's magnetic field. The inner core is the centermost layer of Earth and is in many ways similar to the outer core.
It is also primarily iron and nickel and has a radius of about 1, km. The differentiation between the outer core and inner core is density driven. The pressures become high enough that despite very high temperatures, the inner core is solid. It is also enriched in unusual heavy elements including gold, silver, platinum, palladium, and tungsten. Temperatures reach up to 5, degrees Celsius and pressures up to gigapascal. Now, let's answer some commonly asked questions in case you're looking for quick answers.
I hope you enjoyed this guide to the layers of the Earth and it sparked a newfound interest in what lies beneath our feet! This is a BETA experience. You may opt-out by clicking here. More From Forbes. Jul 23, , am EDT. Jul 15, , am EDT. Jul 8, , am EDT. Jul 1, , am EDT. Jul 20, , am EDT. Jul 19, , am EDT. These two layers are often called the lithosphere because they are both composed of solid rock.
The underlying, partially molten part of the mantle, on which the plates slide, is called the asthenosphere. The lithosphere is strong, rigid rock, while the asthenosphere is a weaker, very viscous fluid. Students have learned that the locations of earthquakes and volcanoes provide clues or data that help understand plate tectonics. The causes of these movements are complicated, but at this level students should begin to recognize that some of the stresses come from within the Earth.
In particular, one reason for the movement of the plates may be convection currents within the upper part of the mantle. Convection is the heat-driven circulation of a fluid. In the mantle, heat from deeper in the Earth causes the overlying mantle to circulate. The upper mantle can circulate because it contains a little magma molten rock and behaves like a very hot mush. Mantle convection currents move very, very, slowly.
It is possible that as the mantle convects, it drags the overlying plates along with it.
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