1. Why is understanding the theory of plate tectonics important? 1.Interactions of earth’s crust and mantle result in the formation of Earth’s surfaces and are the cause of earthquakes and volcanoes. 2.Cracks in the crust and mantle are called faults 3.P. 443 of earth science book shows a map of California. The San Andreas Fault is moving Los Angeles, towards San Francisco at about 5 cm/yr. In about 100 years = neighbors.

2. South America is moving away from Africa at about 3 cm/yr Hawain Islands are moving north west (towards Japan) at 9 cm/yr Mt. Everest is still rising. Hypothesis: Continental Drift 1.Pangaea 2.Evidence 1.Rock formations - 2.Fossils 3.Ancient climate clues

3. Why did scientists reject this hypothesis? What eventually convinced them that it was correct? 1.Seafloor spreading 2.Geomagnetic Time scale and magnetic reversals. Theory of Plate Tectonics: Earth’s crust and rigid upper mantle are broken into enourmous slabs called plates.

4. Plate Boundaries: 1.Divergent boundaries- two tectonic plates are moving apart. 2.Convergent boundaries – two tectonic plates are moving toward each other 1.Oceanic crust converging with Oceanic crust 2.Oceanic crust converging with continental crust 3.Continental crust converging with continental crust.

5. Fault- when the crust fails and fractures due to too much stress or stress too quickly. 1. Reverse fault- due to compression 2. Normal fault- due to tension 3. strike-slip fault- due to horizontal shear stress. Earthquake waves: Primary waves – P Secondary waves – S Surface wave

6. Earthquakes generate the 3 type of seismic waves. Focus – point where an earthquake originates Epicenter – the point of the earth’s surface directly above the focus.

7. 3. Transform boundaries – Where two plates move horizontally past each other. Convection current in the Asthenosphere (upper mantle. Stress – force exceeding the strength of the rock 1.Compression-towards each other 2.Tension-pulling apart 3.Shear- distortion in all directions Strain = deformation of materials due to stress

8. Outer core inner core Mantle Crust