LAYERS OF THE EARTH
CRUST
- The earth’s rocky, outer surface. The crust is about 80 km thick. It is
made up of solid rock and lies under all of the earth’s surfaces. New
rock is made at rift valleys under the oceans and pushes rock apart
like conveyor belts. It is thin under the oceans and thick under the
continents.
MANTLE
- A layer of dense rock about 1800 km thick. It is made up of liquid
rock called magma that moves about in currents. These convectional
currents heat up in the earth’s middle and rise towards the crust.
OUTER CORE
- The outer core is about 2000 km thick and is made up of heavy
metals. It is like Jell-O and made up of semi-solid rock.
INNER CORE
- This part of the core is about 1400 km thick and is thought to be made
of solid nickel and iron. It is the hottest part of the earth but gravity
stops the material from turning to liquid (3700 C). The centre of the
inner core (and of the earth) is about 6370 km into the earth.
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Other Subsections of the Earth
Lithosphere - Includes the crust and uppermost mantle to about 80km.
Asthenosphere – Goes from about 80km down to 250km down. Is known
as the plastic layer and is susceptible to convection currents which create
tectonic activity (e.g folding/faulting, and general deformation of rocks).