 The theory of plate tectonics explains the formation, movements, and subduction of the earth’s plates. ◦ What is a plate?  A section of lithosphere that slowly moves over the asthenosphere, carrying pieces of continental and oceanic crust.

 What is a fault? ◦ A fault is a break in the Earth’s crust where masses of rock slip past each other.  Where are faults located? ◦ Faults are located on the edges of Earth’s plate boundaries.  There are three types of plate boundaries: ◦ divergent boundary ◦ convergent boundary ◦ transform boundary

 Two plates move apart  Most occur along mid-ocean ridges where sea-floor spreading occurs  Divergent boundaries that occur on land are called: ◦ rift valleys The Great Rift Valley in East Africa

 Two plates come together or converge  Results in a collision  What determines which plate comes out on top? ◦ Density determines which comes out on top, the more dense one sinks under the less dense plate  What happens when the density is the same? ◦ mighty mountain ranges are formed

 Plates slip past each other, moving in opposite directions  What major geological event happens at transform boundaries? ◦ earthquakes