1. Revision Time:

2. Inside the Earth

4. 
The earth's crust is split into a series of plates.

The places where plates meet are called plate
boundaries.

These plates float on the heavy molten rock of the
mantle.

Continental drift means that the continents of the
world are carried along by the plates beneath them.

Plates can collide and seperate.

5. 
The Plates:

Eurasian Plate

African Plate

Pacific Plate

Nazca Plate

Australian Plate

6. When Plates collide

Fold mountains are formed

Earthquakes occur

7. When plates separate

Volcanic islands, volcanic mountains and mid ocean ridges
are formed.

8. Folding and fold mountains

Fold mountains are created when two plates collide.

When the plates compress ( push together) the earths crust
begins to arch upwards.

9. 
Young fold mountains include the Alps and the Rocky
mountains,these were formed about 35million years ago.

Ireland's fold mountains are very old and tend to be flat.
They were formed 250 million years ago.

10. Earthquakes

Earthquakes happen when two plates collide or slip past one
another .

When the plates compress ( crush together) cracks form in
the earths crust. The area of compression is called the focus.

The focus sends out shock waves through the crust,
reaching the surface.

The area of the surface hit by the worst shock wave is called
the epicentre.

11. 
The epicentre is the most dangerous area of an earthquake.

A seismograph measures the earthquakes strength.

Earthquakes are rated on the Richter Scale

12. 
Earthquakes can cause buildings to collapse, roads to crack,
mudslides and tsunamis.

13. Volcanic Activity

Where plates seperate or collide the earths crust cracks and
lets through hot liquid rock called magma.

The magma forces its way up through a long hole in the
mantle known as a vent

Once the magma hits the earths surface it is now called
lava.

When plates seperate the lava may form ridges in the earths
surface known as mid ocean ridges.

The most famous ridge is the Mid Atlantic Ridge.

14. The Mid Atlantic Ridge

The Mid Atlantic Ridge was created when the Eurasian and
the American Plates seperated.

The Mid Atlantic Ridge starts at the top of the Atlantic
Ocean and runs all the way through down to the bottom.

Iceland is a volcanic Island on the Mid Atlantic Ridge.

Famous volcano's in Iceland include Mount Krafla and the
island of Surtsey.

15. The formation of a volcano:

When the magma reaches the top of the vent, it bursts
through the earth's surface.

Lava, ash and mud explode from the surface.

The hot lava then flows and spreads out destroying the land
around it.

When the lava cools and hardens it becomes cone shaped
and eventually creates a volcanic mountain.

17. 
Volcanos can be active, dormant or extinct.

Active : erupts regularly

Dormant: has not erupted for along time

Extinct: has not erupted in historic times.

18. The Pacific Ring of Fire

This is an area in the Pacific Ocean where there are huge
amounts of volcanos and earthquakes.

There have also been numerous tsunamis in and around the
ring.

19. 
Best of luck in the test