You would possibly never have guessed just by looking at it but the Earth
actually consists of four layers. The layer we are all familiar with the
topmost layer called the crust. The
Earth's crust is the dirt we dig in to plant trees and flowers. Mountains
and ocean floors also form part of it. It is more than 32 kilometers thick
in some places.
The Earth's crust floats on top of the
mantle. The mantle is the Earth's
midsection. It comprises rocks and metals that are so hot they melt! The
temperature inside the mantle is about 1,200 degrees Celsius. The molten
rocks become lighter and rise up to wards the crust. Wherever there are
cracks in the crust or weak spots, the molten rocks ( now called magma )
escapes to the surface. What do you get ? Lots and lots of earthquakes and
volcanic eruptions !
Deeper down is the Outer Core. The Outer Core is a 2,240km layer of
melted iron and nickel. Here, the heat traveling through the Outer Core (
caused partly by the Earth's rotation ) creates the Earth's magnetic
field. The magnetic field makes sure everything on the Earth's surface does
not float away into space. That's gravity ! Right in the centre of the Earth
is a solid ball of iron and nickel called the Inner Core. The temperature of
the Inner Core is almost as hot as the sun ! Though it's hot enough to melt
iron, the tremendous pressure caused by the weight of all the layers
compacts the center into the solid ball.