Seafloor spreading

• • 2 plate move away from each other at divergent plate boundaries, seafloor spreading occur
  • Magma from deep within earth rises through the mid-ocean ridge
  • New oceanic crust in formed
• Evidence to support plate tectonic theory

  • Rocks nearer to the crest/centre of the mid-ocean ridge are the youngest
  • Rocks further away from the ridge are progressively older
• Evidence to support plate tectonic theory

  New oceanic crust is created at divergent boundaries & then moves laterally on both sides of the mid-ocean ridge as seafloor spreading continues
• Evidence to support plate tectonic theory


  Little sediment accumulation is found at oceanic trenches, as older oceanic crust is being destroyed
• Evidence to support plate tectonic theory

  Oceanic crusts are usually younger than continental crust