Appropriate for elementary level science students, this slideshow examines the Earth's structure from the inside.

1. The Interior of the
Earth
By Moira Whitehouse PhD

2. The surface of the Earth is constantly
changing as new landforms are built
and older ones are destroyed by the
forces of the Earth.

3. Some changes happen so slowly that
you do not see the differences for a
long time—for example the Colorado
river carving the Grand Canyon has
been happening for millions of years.
On the other hand, volcanic eruptions and
earthquakes can change the surface of the
Earth very quickly.

4. How are Landforms Made?
• Now let’s examine the forces that
create the different landforms. Broadly
speaking, there are two kinds:
•Constructive forces—those that build up the
land.
• Destructive forces—those that wear down
the land.

5. To understand the constructive forces of
the Earth—the ones that build up
landforms, we need to understand what
the interior (the inside) of the Earth is
like.

6. What’s inside the
Earth?

7. Let us look at the inside of the Earth.
If you were able to cut the Earth in
half, you would find it is made up of
different layers.

8. NASA image

9. The thin, outermost layer of the earth is
made of solid rock and is called the crust.
All of the landforms on Earth are located
Crust
on the crust and all life on Earth exists on
this top layer.

10. The Earth’s crust consists of the oceanic and
the continental crusts, both of which float on
the magma (melted rock).
• The oceanic crust is the layer of
rock which forms the floor of an
ocean. It is about 4-7 miles thick.
• The continental crust is the layer of rock
which forms the continents and those areas
magma
of shallow seabed close to the shore. The
continental crust is much thicker than the
oceanic crust--about 19 miles thick.

11. The continental crust is mainly made of a
rock called granite.
The oceanic crust is made of mostly
basalt, a very dense rock that is much
heavier than the granite of the continental
crust.
As a result, the oceanic crust sinks deeper
into the magma (the molten rock) when
the continental and oceanic crust meet.

12. This rock
is mainly
granite.
This rock
magma is mainly
basalt.

13. The mantle is the layer directly below the
crust.
NASA image
• It is about 1800 miles thick and made of
melted rock.

14. As you get closer to the center of the Earth
the hotter it is. This explains why the rock in
the mantle is molten (melted).

15. The cooler (heavier)
melted rock in the
mantle sinks as the
hotter (lighter) melted
rock rises, creating
convection currents.

16. Below
the
mantle
is the
core, the
center
of the http://www.freedigitalphotos.net
earth.

17. Inner core, solid iron
The core is also
and nickel
divided into two
regions, the inner
core and the outer
core. Scientists
believe the outer
core is a liquid and
the inner core is a
solid.
Outer core, liquid iron

18. Let’s see how the
make-up of this
planetary ball
affects how some
landsforms are created.
Remember that landforms are
found on a very thin crust
floating on top of a thick layer of
molten (melted) rock called
magma. http://scign.jpl.nasa.gov/

19. Plates Make up the
Crust of the Earth

20. Next, the crust of
the Earth is
broken into huge
pieces of rock
called plates.
These plates fit
together around
the globe like a
giant jigsaw
puzzle.

21. The platesfloat on the
hot, melted rock
found in the mantle.
Creative Commons
Wikipedia Commons

22. • We learned that because of convection the
magma below the magma flows, very slowly,
in large patterns.
Creative Commons
Wikipedia Commons

23. Because of convection,
the cooler (heavier)
melted rock in the
mantle sinks as the
hotter (lighter) melted
rock rises creating
convection currents.
These currents rub
against the bottom of
the plates and cause
the crustal plates to
move.

24. Map courtesy NOAA
Here are the 7 major plates plus several smaller ones.

25. Another day we will see how the
knowledge you have gained about the
interior of the Earth and the plates that
make up Earth’s crust helps you
understand how some Earth’s
landforms are formed.