From Pangea to Plate Tectonics

1. From Pangea to Plate Tectonics Earth’s Plates In Motion Andrew Flint August 8, 2002

2. Contents • What is Pangea? • The theory of Continental Drift • Seafloor Spreading • What is Plate Tectonics? • Timeline • Questions • Ideas for further study • Bibliography

3. Pangaea • The word “Pangaea” means “all land” • Scientists believe that the continents once looked like this:

4. Alfred Wegner and the Theory of Continental Drift • In 1912 Alfred Wegner theorized that the continents had once been together and had “drifted apart. They fit together like puzzle pieces. • Rock formations, climate similarities, and plant & animal species gave further evidence.

5. Seafloor Spreading • In the 1950’s scientists began to look at the ocean floor for evidence of this movement. • They noticed deep sea trenches and rifts. • Age Evidence and Magnetic Clues provided further evidence that Wegner had been correct!

6. Plate Tectonics • In the 1960’s scientists theorized Plate Tectonics. • Earth is made of 10 plates that “slide” around on the plastic-like layer of the earth below the crust called the asthenosphere.

7. Plate Boundaries • Convergent- Plates collide…volcanoes, mountains • Divergent- Plates move apart…ridges, rift valleys • Transform- Plates slide past one another…earthquakes

8. Timeline • 1912 Alfred Wegner-Continental Drift • 1950’s Seafloor Spreading • 1960’s to present- Plate Tectonics

9. Do You Remember? • 1. Define Pangaea. • 2. Describe Wagner’s theory. • 3. What evidence is there of Seafloor Spreading? • 4. Describe Plate Tectonics. • 5. Name and describe the 3 Plate Boundaries.

10. I’d Like To Know More… • How much do the plates move in a year? • Which direction are we moving in? • Can we stop the movement? (earthquakes)

11. Bibliography • Earth Science, Glencoe/ McGraw Hill. Columbus, Ohio, 2001 • Research and images , http://www.enchantedlearning.com