SCI 10

• The lithosphere is the solid outer layer

  of Earth which consists of the crust and the

  uppermost part of the mantle.
• The crust is

  mostly made up of basalt and granite igneous

  rock.
• The basaltic rock makes up the oceanic

  crust while the granitic rock makes up the

  continental crust.
• The crust is mechanically

  brittle at some locations and extends about

  80km to 150 km deep.
• Beneath the lithosphere is the weak, partially molten asthenosphere – the

  part of the upper mantle that behaves like plastic.
• The plasticity of the

  asthenosphere allowed the plates to glide slowly at a rate ranging from less than 1

  cm to 16 cm per year.
• major tectonic plates such as the Eurasian Plate, North

  American Plate, Pacific Plate, South American Plate, African Plate, Antarctic Plate

  and Australian Plate.
• Tectonic plate movement is powered by the internal energy of the mantle