The Structure of the Earth

• A layer of rock very thin compared to the diameter of the entire Earth
• Crust may be continental or oceanic crust

• A thick layer of solid, dense rock rich in magnesium and silicon
• Parts of the mantle move very slowly
• Temperature ranges from 1000 - 3000 degrees C

• Very dense liquid iron and nickle
• At a high temperate (4000 degrees C)
• The Earth's magnetic field arises here

• Solid Iron and nickle
• Very high temperatures (6000 degrees C)
• Solid due to the pressure it is under

The surface of the earth is broken into about 25 pieces. These pieces float on the surface of the mantle

The constant motion of the plates is driven by convection currents from deep within the mantle

The constant decay of radio active elements produces heat

Convection Current - hot, low densit rock moves upward and displaces cooler more dense rock which then sinks and is heated and so on

The surface of earth has been in a constant change since the crust first formed

There are only two known places on earth where you can see the original crust: places in Australia and Greenland

The idea that the earth's surface is split into plates was proposed in 1912 by a German calle Alfred Wegener. He proposed that millions of years ago the continents were once joined to form one super continent called Panaea. About 250 million years ago, Panagea began to break up, moving towards the positions they are in today.

The continents of Africa and South America and other areas are shaped as if they once fitted together

Common fossils and rock structures occure on different continents

Earthquakes and volcanoes occur at certain points where the plates meet