Last lecture, I gave you a brief overview of plate tectonics. It is the cold, strong layer we walk around on, and is generally around 50-100 km thick. Asthenosphere Region of the mantle directly below the lithosphere. The lithosphere is broken into several large, rigid plates which move around on the surface. New oceanic lithosphere is created at mid-ocean ridges.
Oceanic lithosphere is destroyed at subduction zones.
The motions of the plates explain most earthquakes, volcanism, mountain building, and continental drift. See Figure 20.3 for a map of the plates. You should learn the names of the plates and where they are located. It's important that you know why continental drift was not accepted and why plate tectonics was accepted. Here's an outline form of the story.