1 Plate Tectonics The Internal Structure (Make-up) of the Earth


The CRUST is the thin outer shell of the earth. It is made up of solid rock that is called the lithosphere. The crust can be divided into continental crust and oceanic crust.


Continental crust (on which our


main land masses are situated):  Is the thickest part of the crust. It is up to 60 kilometres thick in places.


 Is made up of younger, lighter rocks such as granite.


Oceanic crust (which lies under


our oceans):  Is very thin – sometimes as little as 5 kilometres thick.


 Is made up of very old rocks such as basalt.


Landmass


Lithosphere Rigid rock in crust and top margin of mantle


Asthenosphere Semi-molten rock


Sea


Continental Crust


Mantle 1 The earth’s internal structure 1


The OUTER CORE is made up of hot, molten rock.


The MANTLE lies between the crust and the core of the earth. Although very hot, most of the mantle remains solid.


Close to the crust, that part of the


mantle called the asthenosphere can sometimes become semi-molten and capable of flowing in very slow- moving currents. Semi-molten underground rock is called magma.


Convection currents of semi-molten rock


The INNER CORE is extremely hot (up to 5,000°C). But it is under such pressure that it remains solid rather than molten.


Oceanic Crust

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