Structure of the Earth

STRUCTURE OF THE EARTH

(http://www.coolgeography.co.uk/A-level/AQA/Year%2013/Plate%20Tectonics/Plate%20tectonics/Earth_structure.gif)

The Lithosphere

  •  includes the brittle upper portion of the mantle and the crust, 
  • the most rigid of the Earth's layers
  • although the rocks of the lithosphere are still considered elastic, they are not viscous
  • the coolest of Earth’s layers
  • Oceanic lithosphere is associated with oceanic crust, and is slightly denser than continental lithosphere
  • Continental lithosphere, associated with continental crust, can be much, much thicker than its oceanic cousin

The Asthenosphere 

  •  zone of Earth’s mantle lying beneath the lithosphere
  • believed to be much hotter and more fluid than the lithosphere
  • heated by contact with hot materials that make up the mesosphere beneath it
  • extends from about 100 km (60 miles) to about 700 km (450 miles) below Earth’s surface
  • convection currents generated within the asthenosphere push magma upward through volcanic vents
  • Convection currents also stress the lithosphere above, and the cracking that often results manifests as earthquakes

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