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
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.
16.
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.
