Help students explore deep underground with this earth science unit about volcanoes, earthquakes, and plate tectonics. It begins with a review of the layers of the Earth and then explores the continental and oceanic crusts, the lithosphere and asthenosphere, plate boundaries, and subduction. It then explores earthquakes, types of faults, tsunamis, the Richter scale, and several historic earthquakes. The unit concludes with a look at the parts of a volcano, types of volcanoes, indications of a pe