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Table of Contents Drifting Continents 5:1 Pg. 164-167 Sea-Floor Spreading 5:2 Pg. 168-173

Plate Tectonics. Table of Contents Drifting Continents 5:1 Pg. 164-167 Sea-Floor Spreading 5:2 Pg. 168-173 The Theory of Plate Tectonics 5:3 Pg. 174-179. Inside Our Planet. Drifting Continents 5:1.

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Table of Contents Drifting Continents 5:1 Pg. 164-167 Sea-Floor Spreading 5:2 Pg. 168-173

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  1. Plate Tectonics Table of Contents Drifting Continents 5:1 Pg. 164-167 Sea-Floor Spreading 5:2 Pg. 168-173 The Theory of Plate Tectonics 5:3 Pg. 174-179

  2. Inside Our Planet

  3. Drifting Continents 5:1 • Alfred Wegener, a German scientist, hypothesized that all the continents were once joined together in a single landmass and have drifted apart. • Wegener called this single landmass, or supercontinent, Pangaea. • This theory became known as Continental Drift. http://www.agci.org/classroom/geosphere/animations/pangea-animation.php

  4. Continental Drift

  5. Drifting Continents 5:1 • Wegener used evidence from: • * Land Features • * Fossils • * Climate • His hypothesis was rejected, however, because he could not explain HOW the continents moved to their present day location.

  6. Sea-Floor Spreading 5:2 • The mid-ocean ridge forms the longest chains of mountains in the world, rising up from the ocean floor. Ocean Floors Mid-ocean ridges rise from the sea floor like stitches on the seams of a baseball.

  7. The Sea-Floor is Spreading

  8. Sea-Floor Spreading 5:2 • Sea-floor spreading adds more crust to the ocean floor. At the same time, older strips of rock move outward from either side of the ridge. • Evidence for sea-floor spreading comes from: • Pillow like lava rocks on the ocean floor • Magnetic stripes follow similar patterns on either side of the ridge • Ages of rocks are older further from the mid-ocean ridge

  9. Sea-Floor Spreading 5:2 • In a process taking tens of millions of years, part of the ocean floor sinks back into the mantle at deep-ocean trenches in a process called subduction. http://www.planetseed.com/files/flash/science/features/earth/livingplanet/plate_boundaries/en/index2.html?width=570&height=475&popup=true

  10. The Theory of Plate Tectonics 5:3 • The theory of plate tectonics states that Earth’s plates are in slow, constant motion driven by convection currents in the mantle.

  11. Plate Tectonics

  12. The Theory of Plate Tectonics 5:3 • Plates meet at one of three types of plate boundaries: • Divergent • Convergent • Transform

  13. Ticket Out The Door • Use the index card corresponding with your number to create one question about Plate Tectonics that can be answered by another student.

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