1. Plate Tectonics Chapter 10

2. ACTIVITY PLATE TECTONIC PUZZLE 1. Reconstruct Pangaea 2. What evidence led to your conclusion? 3. What landmasses logically fit together? 4. What other evidence led you to believe the continents fit together?

3. Early Earth and Plate Tectonics The early Earth & Plate Tectonics

4. The Earth’s Drifting Continents German scientist Alfred Wegener, 1900’s proposed the Theory of Continental Drift… he was not the only one to do this… he was able to collect evidence though

5. Shoulder Partner 1. How could you prove a theory like this? 2. How do you convince people to support your ideas/thoughts?

6. Evidence 1. Glossopteris (gymnosperm… seed fern), located in 250 myo rocks, were found in South Africa, Australia, India, and Antarctica 2. Antarctica once had a warmer climate 3. Rock formations and deposits lined up on several continents 4. Evidence of glaciers in now warm climates

7. The Evidence Same fossils on different continents Same species of plants and rock formations on different continents

8. Face Partner  Can you think of any other evidence that Wegener could use?

9. The Real Issue……….. How could the continents move through the solid rock bottoms of the oceans? In the 1950’s, scientists using better instruments found underwater mountain chains with rift valleys in their centers

10. Midocean ridge

12. Earth’s Spreading Ocean Floor A. Mid-ocean ridges form the single largest mountain range in the world (under the oceans) B. 80,000 km long and 3 km high C. Lava erupts to form new sea floor D. As it spreads it takes continents with it This explained the mechanism for continental drift!

13. Shoulder partner  Explain to your partner how we know the sea floor is spreading.

14. Seafloor Spreading

15. Iceland, "the land of fire and ice", is being split by an oceanic ridge that surfaces to create an oceanic island in the North Atlantic Ocean. Iceland, "the land of fire and ice", is being split by an oceanic ridge that surfaces to create an oceanic island in the North Atlantic Ocean.

16. Interesting Iceland 1. Slightly smaller than Kentucky 2. Average temperature is 11°C (52°F) in July and -1°C (30°F) in January 3. Natural hazards: Earthquakes and volcanic activity; avalanches 4. Environment issues: Water pollution from fertilizer runoff; inadequate wastewater treatment 5. More land covered by glaciers than in all of continental Europe 6. Number of volcanoes: 43

17. Magnetic stripes on the ocean floor were further evidence that the sea floor was spreading. The patterns are identical on each side of the ridge Closer examination shows that the magnetic poles have reversed themselves anywhere from 9-2,000 times in the past 3.5 million years… depends on the strength of the field tested.

18. Pole Reversal The magnetic pole is currently 966 kilometers (600 miles) from the geographic one. The magnetic pole lies in the Arctic Ocean… it is currently migrating toward Siberia Earths Magnetic Field

19. Oceanic Ridges LITHOSPHERIC PLATES

20. Thousands protest against Global Warming!!!

21. If the ocean floor is being created, is the Earth getting bigger?... No Rock in the ocean is relatively young Rock in the ocean is relatively young Ocean floor is being destroyed in trenches in a process called subduction Ocean floor is being destroyed in trenches in a process called subduction The denser ocean crust is pushed downward into the mantle and melts The denser ocean crust is pushed downward into the mantle and melts It is a cycle… some goes down and some goes up It is a cycle… some goes down and some goes up

22. Some comes up Some goes down

23. The Earth’s Moving Plates The Theory of Plate Tectonics, which links continental drift and seafloor spreading, explains how the Earth has evolved over time. It helps to explain the formation, movement, collisions, and destruction of the Earth’s crust

24. PLATE TECTONICS

25. Lithospheric Plates  There are seven major plates, Pacific, North American, South American, Eurasian, African, Indo-Australian, and Antarctic  There are many small plates, Caribbean, Arabian are examples  Each plate moves at a different speed and direction  Some are oceanic and some are continental

28. Table Talk 1. How would plate boundaries act differently if ocean plates hit each other or if ocean plates hit continental plates 2. Would there be a difference? 3. What would happen, what would form?

29. ACTIVITY 1.Label & color the seven major plates 2.Answer the questions on the back

30. Sand Art… Relax while you work Sand Art… Relax while you work

31. Moody Slide… hopefully it will work

32. Will the Earth Continue to Change?

34. The Floating Crust Isostasy is the balance between the downward force of the crust and the upward force of the mantle

35. Plate Boundaries Divergent boundary- plates moving apart

36. C to C forms a rift valley that fills in w/ seawater: Iceland or African Rift Valley O to O forms a mid-ocean ridge: Mid-Atlantic Ridge

37. Convergent boundary- plates that are moving together

38. Collision of Continental and Oceanic Plates = Trench and Volcanic Arc Pacific Coast, Washington State

39. Collision of 2 Continental Plates = Mountain Range Himalayas (India)

40. Collision of 2 Oceanic Plates = Trench and Island Arc

41. Transform boundary, slip-strike, lateral faults- plates slide past one another resulting in earthquakes San Andreas Fault is this type… and no CA will not fall into the ocean…. LA will be a suburb of San Francisco

42. Plate Motion The power of the convection currents in the mantle is thought to be the force that moves the plates

43. The Earth’s Changing Surface Stress is what causes the surface of the Earth to change As the rocks undergo stress, they slowly change shape and volume They also move up and down or sideways

44. Types of Stresses  Compression squeezes the rock (Convergent)  Tension causes the rocks to stretch out over a larger area (Divergent)  Shearing of the rock causes it to twist or tear (Transform)

46. Faulting A break or a crack along which rocks move Earthquakes are sometimes along these faults

47. If the rock above the fault moves down, the fault is termed normal (tension), whereas if the rock above the fault moves up, the fault is termed reverse (Compression)

48. Faulted Mountains and Valleys  Mountains formed when there are many normal faults in one area  Blocks of rock are uplifted  Valleys may form when the block of land between 2 normal faults slides downward

49. Folded Mountains When stress is applied to the rock formation and it bends but doesn’t break When stress is applied to the rock formation and it bends but doesn’t break Forms an anticline which is an upward fold and a syncline which is a downward fold Forms an anticline which is an upward fold and a syncline which is a downward fold

50. Anticline v. Syncline Synclines Sink

51. Volcanic Mountains Single peak mountains formed from volcanoes

52. Yellowstone Yellowstone Super Volcano Alert