The Restless Earth – Revision

The Restless Earth – Revision

Image courtesy of Lawrence Livermore National Labs

Crust: The outer shell of the earth is made of solid rock. It is 35km thick.

Mantle: Very hot. Some rocks are semi-molten and flow about in slow moving currents.

Core: The very middle which is very hot but solid iron.


200 million years ago all of the present day continents combined to form a super continent called Pangaea.

Tectonic Plates

  1. American Plate
  2. Pacific Plate
  3. Nazca Plate
  4. African Plate
  5. Eurasian Plate
  6. Pacific Plate
  7. Australian Plate

Tectonic Plates
(Credit: Encyclopædia Britannica, Inc.)

The magma underneath the crust moves inwards or outwards. When it is moving inwards then the plates may collide causing Fold Mountains.

The formation of fold mountains. (Image courtesy BBC)

When the magma moves outwards it causes the plates to separate causing Volcanic Islands,Volcanic Mountains and long Mid-ocean ridges.

Volcanic activity and the Earth’s tectonic plates.
(Credit: Encyclopædia Britannica, Inc.)

Diagram of an earthquake.
(Image courtesy BBC)


Earthquakes are formed when plates collide or slip past each other. This causes compression that the rock beneath bends and cracks suddenly.

  • Shock waves are spread from the focus.
  • The epicenter is usually where the earthquake is its strongest.
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