Ch 9 Notes

1. Ch 9 Notes Mr. Russo Beaumont High School

2. Ch 9 Vocab Matrix (Pg 45) • Divergent boundary • Convergent boundary • Transform fault boundary • Oceanic Ridge • Rift Valley • Seafloor Spreading • Subduction Zone • Trench • Continental Volcanic Arc • Volcanic Island Arc • Paleomagnetism • Hot Spot

3. Objective: Ch 9.1 Pg 47 • We will be able to describe the 4 pieces of evidence for the theory of continental drift.

4. Continental Drift • Continental Drift – The continents had once been joined to form a single supercontinent • Proposed by Alfred Wegner

5. Pangaea • Pangaea – The supercontinent (All Land) • Continents broke apart and drifted to their current position

6. What evidence supports continental Drift? • Continental Puzzle – Continents appear to form a puzzle that can be put together

8. What evidence supports continental Drift? • Matching Fossils – Several of the same types of fossils on different landmasses

9. What evidence supports continental Drift? • Rock Types and Structures – Mountain belts that end on one coastline seem to reappear on a landmass across the ocean

10. What evidence supports continental Drift? • Ancient Climates – Found evidence of glacial ice in countries that shouldn’t have any glaciers

12. Objective

13. Ch 9.2What is the theory of plate tectonics? • The upper mantle and the crust act like a strong rigid layer. • This layer is called the lithosphere

14. The lithosphere lies on top of the weaker mantle called the ASTHENOSPHERE

15. Plates • Plate – Plates are sections of the lithosphere • 7 Major plates • Largest – Pacific Plate • Plates move 5cm/yr

16. What are the 3 types of plate boundaries? • Convergent • Divergent • Transform

17. Divergent Boundary • Divergent Boundary – Occur when two plates move apart • Example – East African Rift Valley

18. Example – East African Rift Valley

19. Convergent Boundary • Convergent boundary – Occur when two plates move together

20. Transform Boundary • Transform Boundary – When two plates grind past each other • Example – San Andreas

21. Every Plate contains all 3 types of boundaries

22. Ch 9.3Oceanic Ridge • Oceanic Ridge – Elevated area in the ocean, found along divergent boundaries

23. Rift Valley • Rift Valley – Deep faults found along divergent boundaries

24. Seafloor Spreading • Seafloor Spreading – The process by which plate tectonics produce new lithosphere • Oldest part of the ocean floor is 180 million years old.

25. Subduction Zone • Subduction Zone – When one plate is forced down beneath another plate. (Convergent Boundary)

26. Trench • Trench – Surface Feature produced during a subduction zone.

27. Continental Volcanic Arc • Continental Volcanic Arc – When a continental and ocean plate collide, they produce volcanoes on the land.

28. Volcanic Island Arc • Volcanic Island Arc – When 2 ocean plates collide, they produce volcanoes in the middle of an ocean, forming islands

29. Mountains • Mountains are formed when two continent plates collide. • Example – Himalayas in South Asia

30. Transform Fault - Earthquakes • Transform Fault – Earthquakes – At Transform faults, plates grind past without destroying the lithosphere and produce earthquakes. • Example – San Andreas Fault , CA

31. Notice • Convergent Boundaries – Lithosphere is destroyed • Divergent Boundaries – Lithosphere is created • Transform Boundaries– Lithosphere is neither created nor destroyed.

32. Ch 9.4Paleomagnetism • Paleomagnetism – Study of changes in Earth’s magnetic field

33. Normal Polarity • Normal Polarity – Same magnetism as present day magnetic field

34. Reverse Polarity • Reverse Polarity – Rocks that show opposite magnetism then present day

35. What evidence supports theory of plate tectonics? • The discovery of strips of rocks of alternating polarity across the ocean ridges.

36. How old is the seafloor? • The youngest crust (Seafloor) is at the ridge crest, the oldest crust is further away Youngest Oldest

37. Hot spot • Hot Spot – A rising plume of mantle that creates a volcanic area (Hawaii) • Hot spot supports idea that the plates move over Earth’s surface

38. Shaded Region – Reverse Polarity • White Region – Normal Polarity