Structure of the earth

• Earth


  Made up of three main layers: the core, the mantle and the crust
• Earth's layers


  • Become more dense toward the centre of the earth
  • Density increases with depth as a result of higher temperature and greater pressure
• Core


  • The innermost layer of the earth
  • Very dense and extremely hot
  • Temperature rises to about 5500 °C at the centre
  • 1640km below the surface
• Mantle


  • Between the crust and the core
  • Makes up 82% of the volume of the earth
  • Extends to a depth of 12900km
  • Rocks are in a molten state as temperatures are over 1200°C
• Crust


  • Solid and accounts for about 1% of the earth's volume
  • Up to 5km deep below the oceans
  • 20-65 km deep below the surface of the continents
• Types of crust


  • Continental crust
  • Oceanic crust
• Continental crust (Sial)


  Silica (Si) and Aluminium (Al) are very common
• Oceanic crust (Sima)


  Made up mainly of basalt where silica (Si) and magnesium (Mg) are dominant
• Continents occur


  Where continental crust rests on top of oceanic crust
• Oceanic crust is continuous around the earth's surface
• Super continent


  Pangea
• First ocean


  Panthalassa