Plate Tectonics

1. Plate Tectonics CHAPTER 8 EXIT CHAPTER 8.1What Is Plate Tectonics? 8.2Types of Plate Boundaries 8.3Causes of Plate Movement 8.4Plate Movements and Continental Growth CHAPTER OUTLINE

2. 8.1What is Plate Tectonics? Africa South America Fossil evidence found in South America and Africa support the hypothesis that the continents were once joined. Areas in which mesosaurus fossils have been found CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Alfred Wegner proposed the hypothesis of continental drift to explain how a single land mass had separated into separate continents, which drifted apart. plate tectonics continental drift mid-ocean ridge SECTION OUTLINE

3. 8.1What is Plate Tectonics? CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Alfred Wegner proposed the hypothesis of continental drift to explain how a single land mass had separated into separate continents, which drifted apart. plate tectonics continental drift mid-ocean ridge Later discoveries supported the idea that the continents had been connected, but demonstrated that the continents were not “drifting” but attached to moving lithospheric, or tectonic, plates. SECTION OUTLINE

4. 8.1What is Plate Tectonics? Earthquakes Volcanoes CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY The theory of plate tectonics explains the occurrence of volcanoes and earthquakes in concentrated belts along plate boundaries. plate tectonics continental drift mid-ocean ridge SECTION OUTLINE

5. 8.1What is Plate Tectonics? Mid-Atlantic Ridge, Atlantic Ocean East Pacific Rise, Pacific Ocean CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Plate tectonics also account for a distinctive pattern in the age and magnetism of rocks that spread out from mid-ocean ridges on the ocean floor. plate tectonics continental drift mid-ocean ridge SECTION OUTLINE

6. 8.2Types of Plate Boundaries Characteristic Features Current Examples Type of Boundary Process Involved sea-floor spreading • mid-ocean ridges • rift valleys • earthquake activity at fracture zones along mid-ocean ridges • volcanic activity • Mid-Atlantic Ridge • East Pacific Rise Divergent CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Plates move apart at divergent boundaries. A rift valley is an example of a divergent boundary on land. divergent boundary rift valley rift convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

7. 8.2Types of Plate Boundaries Characteristic Features Current Examples Type of Boundary Process Involved ocean-ocean subduction • deep-sea trenches • volcanic island arcs • earthquake activity • islands of Indonesia • Mariana Islands Convergent CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Plates move toward each other at convergent boundaries. One plate may subduct under the other, as happens at deep-sea trenches, or the two plates may collide. divergent boundary rift valley rift convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

8. 8.2Types of Plate Boundaries Characteristic Features Current Examples Type of Boundary Process Involved ocean-continent subduction • deep-sea trench bordering continent • volcanoes along coast of continent • earthquake activity • western coast of South America Convergent CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Plates move toward each other at convergent boundaries. One plate may subduct under the other, as happens at deep-sea trenches, or the two plates may collide. divergent boundary rift valley rift convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

9. 8.2Types of Plate Boundaries Characteristic Features Current Examples Type of Boundary Process Involved continent-continent collision • high continental mountain chains • earthquake activity • Himalayas Convergent CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Plates move toward each other at convergent boundaries. One plate may subduct under the other, as happens at deep-sea trenches, or the two plates may collide. divergent boundary rift valley rift convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

10. 8.2Types of Plate Boundaries Characteristic Features Current Examples Type of Boundary Process Involved plates sliding past each other • earthquake activity • San Andreas Fault • North Anatolian Fault (Turkey) • fracture zones along mid-ocean ridges Transform CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Plates move past each other at transform boundaries. divergent boundary rift valley rift convergent boundary subduction boundary deep-sea trench collision boundary transform boundary SECTION OUTLINE

11. 8.3Causes of Plate Movement Mid-ocean ridge Deep-sea trench Deep-sea trench Mantle convection This image shows one model of how mantle convection may contribute to plate movement. This image shows as section of the East Pacific Rise, a mid-ocean ridge. CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY and slab pull are hypothetical models for the causes of plate movements. Mantle convection, ridge push, mantle convection ridge push slab pull SECTION OUTLINE

12. 8.4Plate Movements and Continental Growth Pathalassa Ocean Tethys Sea Pangaea 200 million years ago CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane SECTION OUTLINE

13. 8.4Plate Movements and Continental Growth Laurasia Gondwana 180 million years ago CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane SECTION OUTLINE

14. 8.4Plate Movements and Continental Growth North America Asia Africa South America India Australia Antarctica 65 million years ago CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane SECTION OUTLINE

15. 8.4Plate Movements and Continental Growth North America Europe Asia Africa South America Australia Antarctica Modern Day CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane SECTION OUTLINE

16. 8.4Plate Movements and Continental Growth CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton Plate movements have caused the positions of Earth’s landmasses to shift over time. Scientists think that all continents were once part of a single landmass they call Pangaea. terrane Scientists use fossils, the ages of rocks, and other geologic evidence to reconstruct past land movement. SECTION OUTLINE

17. 8.4Plate Movements and Continental Growth Canadian Shield Platform The North American craton CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton The shapes of the landmasses have also changed. At the core of each continent is a craton, the oldest rock on the continent. terrane SECTION OUTLINE

18. 8.4Plate Movements and Continental Growth CHAPTER 8 CHAPTER HOME Plate Tectonics VOCABULARY Pangaea craton The shapes of the landmasses have also changed. At the core of each continent is a craton, the oldest rock on the continent. terrane Processes associated with plate tectonics add new materials to a continent over time. For example, terranes are blocks of lithospheric plates that contribute to continental growth. SECTION OUTLINE

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