Plate Tectonics

Continental Drift + Sea-Floor Spreading + Paleomagnetism = Plate Tectonics

Earth’s lithosphere is broken up into plates. Beneath this, the hot, weak asthenosphere allows for plates to move. Plates are in motion and continually changing in shape and size. They move very slowly; about 5 cm/yr. The movement is NOT constant but more of stop-and-go (earthquakes!).

Layers of the Earth

Watch this recording of part of a lecture on "The Layers of the Earth".   As you watch, note the following:

• Why do you think we can't drill down to the center of the Earth?
• Which layer is the thinnest?
• Why do you think the asthenosphere needs to flow?