Rift Valleys

  • Convection currents in the asthenosphere cause continental crust to dome upwards.
  • The upward pressure causes the crust to crack leaving an unsupported middle section.
  • The unsupported section collapses forming a rift valley with steep stacks.
  • If the convection currents are strong enough a line of volcanoes will form at the bottom
  • of a rift valley, producing a basaltic rock which will eventually form an ocean floor.
  • The largest of these features is in the African Rift valley which extends 4,000km from Mozambique to the Red Sea.