REVIEW: Lesson Summary

Lesson Summary

Mt. Fuji, a volcano that has been dormant for some time. Photo courtesy of

kla4067/Flickr. Licensed CC BY.

• Tectonic plates float on top of the asenthosphere.

• Inside the Earth radioactive material is decaying, which gives off residual heat. This heat is the source for convection currents. Convection currents can happen because of the differences in density in Earth's materials.

• Tectonic plates move as a result of convection currents in Earth's mantle.

• Erupting magma forms new crust and pushes away old crust at divergent plate boundaries. This movement is associated with the upward part of the convection current. This creates mid-ocean ridges and rift valleys.

• Plates are subducted in ocean ridges at convergent plate boundaries. This movement is associated with the downward part of the convection current. This creates deep ocean trenches and volcanoes.

After you have completed this part of the lesson, you can check the associated box on the main course page to mark it as complete