Always on the move…
What's under your feet? Well, depending upon where you are
now, it could be dirt, rock, or grass. But what's really under your feet? If
you were to dig straight down, what would you find? And how far could you dig?
Could you really dig a hole all the way down to Australia?
First Year Geography
students are often surprised when they learn just what exactly our planet is
composed of. Our planet is made up of a
number of layers .We live on the solid outer crust of the Earth, containing our
continents, seas and oceans, which is about 8-30 km deep.
Under the
crust lies the Mantle; this is mainly composed of a very hot substance called
magma. Below the mantle is the Core. This is our planet’s deepest, hottest
layer.
The Core is made
up of two parts; The ‘Outer Core’ and ‘Inner Core’.
The
Outer Core is about 25500 Km and is made up of liquid metals such as uranium
and platinum. Its temperature can be as hot as 5000 Degrees Celsius. Compare
that with today’s temperature!
The Inner
Core is about 100km thick and is like a solid ball of Iron.
The Earth’s
Crust is cracked in many places. At some of these cracks magma spills out.
Magma that comes out on the Earth’s surface is called lava. If a lot of lava
erupts at once a volcano can form. Sometimes a lot of lava spills out and cools
down to form new crust made out of igneous rocks.
The plate
crack or ‘Boundary’ between Europe and America is under the Atlantic Ocean. It
gets wider by about the width of a finger every year. You can see it on Google
Earth. This means we are actually moving away from America!
In other
parts of the world, plates sometimes collide or slip under each other, and melt
when they come into contact with the magma in the mantle.
All this
movement by plates happens very, very slowly over time but it does mean that
the continents and oceans of the Earth are constantly changing position because
the plates underneath then are shifting. We call this ‘Continental Drift’.
If you look
closely at a map of the Earth you will see it like a large jigsaw; in fact
Africa and South America were once stuck together many years ago! We know this because
many of the rocks in both continents are similar.
Finally, have
a look at this amazing video clip to see how the plates and continents have
caused our continents to drift over time. Ireland was actually once on the Equator;
imagine where we will be in millions of years’ time!
