1. PLATE TECTONICS

2. Continental Drift Theory the continents were once joined into a supercontinent, Pangaea, proposed by Alfred Wegener Hypothezised about 200 mya Pangaea began breaking apart

5. Evidence for Continental Drift Theory Continental Puzzle Africa and South America seem to fit together

6. Matching Fossils Mesosaurus fossils are found in eastern South America and the southern western Africa

7. Rock Types of Structures Similar rock types of the Appalachian Mountains seem to run up through New England, Newfoundland, Scotland, and Scandinavia.

8. Ancient Climates Glacial deposits found in India, Australia, southern Africa. The climate must have been much colder. Vast swamps to form the coal belts in eastern United States indicate the climate must have been warmer.

10. Theory of Plate Tectonics the lithosphere lies over a weaker region in the mantle called the asthenosphere. The lithosphere is divided into plates, move and continually change shape. The continents move at a continuous rate of about 5 centimeters per year. This movement generates earthquakes, creates volcanoes, forms deep sea trenches, and deforms large masses of rock into mountains.

12. Convection currents warm, less dense material rises and cooler more dense material sinks The slow movements of the plates and mantle are driven by the unequal distribution of Earth’s heat.

14. Divergent Boundaries – plates move apart creates new crust New sea floor is created – sea floor spreading

16. Convergent Boundaries – plates move together, crust is destroyed, Subduction zone – continental crust is forced down under the oceanic crust into the mantle

17. Oceanic-Continental Convergence Subduction zones Forms continental volcanic arches such as the Andes Mountains

18. Oceanic-Oceanic Convergence One oceanic crust descends under the other oceanic crust Forms volcanic island arcs Aleutian Islands

19. Continental-Continental Convergence Forms complex mountains such as the Himalayas and Appalachians

20. Transform Plate Boundaries – plates grind past each other without destroying crust Most transform faults located on the sea floor San Andreas Fault in California