Chapter 4: Plate Tectonics

1. Chapter 4: Plate Tectonics PowerPoint Review

2. Section 4.1 Earth’s Interior

3. The crust The mantle The outer core The inner core Can you name Earth’s layers?

4. Crust - a layer of rock that forms Earth’s outer skin This includes both dry land and ocean floor 2 Types of Crust continental crust -the crust that forms the continents (granite) oceanic crust-the crust beneath the ocean (basalt) The Crust

5. The Mantle The mantle is made of three parts: • Lithosphere - uppermost part of the mantle (rigid, hard layer) • Asthenosphere - some what soft and can bend like plastic • Lower mantle - solid layer beneath the asthenosphere

6. Outer Core Molten metal made of iron and nickel The movement of the outer core creates Earth’s magnetic field. Inner Core A dense ball of solid material made of iron and nickel The Core

7. Travel to Earth’s Interior…Impossible Heat Temperature increases 1° C for every 40 meters traveled Pressure Pressure increases as you move deeper into Earth’s interior

8. How Do We Know What’s Inside? • Evidence from rock samples • Drilling samples • Volcanic eruptions blast rock to the surface • Evidence from seismic waves • Geologists study how they travel through Earth

9. Layers of the Earth

10. Section 4.2 Convection in the Mantle

11. There are three types of heat transfer: radiation, conduction and convection.

12. Radiation- the transfer of energy through space No direct contact with the heat source Sunlight Radiation

13. Conduction- heat transfer within a material or between materials that are touching A metal spoon heats up in a pot of boiling water Conduction

14. Convection - heat transfer by movement within a fluid Convection

15. Let’s take a look at heat transfer.

16. Section 4.3 Drifting Continents

17. Alfred Wegener • Wegener’s hypothesis was that all the continents were once joined in a single landmass and have since drifted apart. • Wegener’s evidence to support continental drift included the puzzle-like fit of the continents, similar mountain ranges, glacial deposits, coal belts, Glossopteris fossils as well as fossils from Mesosaurus and Lystrosaurus.

18. A Theory Rejected • Since Wegener couldn’t explain the force that would move massive continents, his theory wasn’t accepted by the scientific community until after his death.

19. Section 4.4 Sea-Floor Spreading Old Sea-Floor New Sea-Floor

20. Mid-ocean ridge - an undersea mountain chain that is part of a long system of mountains that winds beneath Earth’s oceans. The ocean floor is mapped using sonar. Mid-Ocean Ridge

21. Evidence of Sea-Floor Spreading Molten material Magnetic stripes Drilling samples Sea-Floor Spreading

22. How Subduction Happens • Convection currents pull the ocean floor apart at mid-ocean ridges • Magma rises and cools creating new sea-floor. • Gravity pulls old, dense sea-floor down beneath the trench. • Old sea-floor is recycled back into the mantle. Takes 200 million years!

23. Let’s see it in action.

24. Section 4.5 The Theory of Plate Tectonics

25. Plate Boundaries There are three kinds of plate boundaries: spreading boundaries, colliding boundaries, and sliding boundaries.

26. AKA: divergent boundary Two plates move apart Ocean: mid-ocean ridge Land: rift valley Most common type of boundary Spreading Boundaries

27. AKA: convergent boundary Occurs where two plates collide Three Types oceanic/oceanic oceanic/continental continental/continental Colliding Boundary

28. The Himalayas

29. AKA: transform boundary Occurs where two plates move past each other in opposite directions Crust is neither created nor destroyed San Andreas Fault Sliding Boundary

30. The End.