1. Earth Structure and Plate Tectonics EARTHSYS 8: The Oceans Lecture 1 Reading: Investigating Oceanography, Chapter 2

2. Earth Structure and Plate Tectonics Outline Earth’s Interior Continental Drift Seafloor Spreading Plate Tectonics Motion of the Plates History of Continents

3. Seismic waves following earthquakes How do we study Earth’s Interior?

4. Seismic waves following earthquakes

5. Earth’s Interior Layers

6. The Lithosphere Fusion of crust & upper mantle Rigid Thinner beneath oceanic regions

7. Continental Drift Theory proposed by Wegener in early 1900s

8. Evidence of Continental Drift -Fossil record -Mountain ranges -Geographic fit -Glaciation patterns -Rock sequences

9. World Ocean Floor Chart Revealed major ridges and trenches on seafloor

10. Seafloor Spreading Proposed by Hess (1960s)

11. Plate Tectonics

12. Types of Plate Boundaries

13. Plate Tectonics

14. Ocean Formation

15. Mechanism for Plate Tectonics: Convection Model

16. Mechanism for Plate Tectonics: Ridge-push, slab-pull model

17. History of Continents: The Wilson Cycle

18. Summary & Important Concepts Seismology used to map Earth’s interior: crust, mantle, liquid outer core, solid inner core Oceanic crust denser than continental; Isostasy = pressure balance Theories of continental drift and seafloor spreading led to current understanding of plate tectonics

19. Summary & Important Concepts Plates in lithosphere are bounded by ridges, trenches, and faults Divergent plate motion creates new ocean basins; Convergent motion destroys ocean, creates mountains Plate tectonics mechanism not fully known Oceans always evolving

20. Discussion Activity Consider the following questions: How are hydrothermal vents formed? What is a black smoker? What causes pole reversals? What are the implications for marine life, climate, or tides? How might earthquakes affect marine life?