1. 9.3 Theory of Plate Tectonics

2. I. Earth’s Moving Plates A.Earth’s crust is broken into LARGE pieces called “plates” 1.Plates contain continents and oceans 2.Faults = cracks between each plate a.separate each plate

3. B.Cause of Movement: convection currents in the mantle C.Effect: plates move 5 cm per year 1.Results: earthquakes, volcanoes, mountains

4. 9.4: MECHANISMS OF PLATE MOTION

5. I. CAUSE OF PLATE MOTION A. Convection Currents 1. Movement of material due to differences in density a. Warm material less dense & rises b. Cool material is more dense & sinks 2. Occurs in the mantle 3. Heat source: the core (middle of Earth) 4. Plates are the “top” of the currents https://www.youtube.com/watch?v=kwfNGatxUJI

7. II. MANTLE CONVECTION A. Downward movement: 1. Slab-pull: gravity pulls old crust into the mantle 2. Ridge-push: crust slides below into the mantle B. Upward movement: 1. Mantle plumes: rising column of mantle rock to the crust a. Creates "hot spots“ & volcanoes https://www.youtube.com/watch?v=ryrXAGY1dmE