1. THE BEGINNINGS OF PLATE TECTONICS EARTH SCIENCE’S UNIFYING THEORY

2. WHAT IS A UNIFYING THEORY? Unifying theory: a theory that explains many natural phenomena and ties things together in an overarching way

3. HOW DOES IT EXPLAIN THIS?

4. EARTH’S STRUCTURE Crust – the thin relatively light outermost layer of the earth Mantle – thick layer of plastic rock beneath the crust Outer Core – composed of liquid iron and nickel Inner Core – solid composed of iron and nickel

5. OCEANIC CRUST VS. CONTINENTAL CRUST Oceanic Crust – thin, dense, composed mainly of basalt Continental crust – thick, composed of granite

6. BUOYANCY!

7. THE BEGINNINGS OF PLATE TECTONICS Alfred Wegener – a German meteorologist and polar explorer who first proposed the theory of continental drift. https://www.youtube.com/watc h?v=rDKiNwTwaNw

8. ALFRED WEGENER’S FINDINGS Evidence for continental drift: Continents fit together like puzzle pieces Identical fossils found on different continents Mountain ranges with identical rocks found in America and Europe BUT HE HAD NO MECHANISM.

9. ALFRED WEGENER SONG https://www.youtube.com/watch?v=T1-cES1Ekto

10. SEAFLOOR SPREADING – WEGENER’S MISSING MECHANISM Seafloor spreading: The theory that new ocean crust forms at spreading centers on the ocean floor which push the continents apart.

11. THE AGE OF THE SEA FLOOR

12. HARRY HESS https://www.youtube.com/watch?v=G yMLlLxbfa4

13. DISTRIBUTION OF EARTHQUAKES

14. DISTRIBUTION OF VOLCANOES

15. PLATE TECTONICS

16. PLATE BOUNDARIES

17. HOW DOES IT EXPLAIN THIS?

18. MID OCEAN RIDGE

19. TRENCH

20. ABYSSAL PLAIN

21. SEAMOUNTS/VOLCANIC ISLANDS