2. Learning Objectives Students will understand the basic structure of the earth –The solid Earth is composed of a relatively thin crust, a dense metallic core, and a layer called the mantle between the crust and core that is very hot and partially melted. (6-8 ES2E). –The crust is composed of huge crustal plates on the scale of continents and oceans, which move centimeters per year, pushed by convection in the upper mantle, causing earthquakes, volcanoes, and mountains. (6-8 ES2F).

3. Looking at the world map, what do you notice about the shape of the continents? Jot down your ideas on your paper…

4. The thing is…the world didn’t always look like this! It used to look like this:

5. How is this possible?!?!? Geological Changes—3:25

6.  The lithosphere is divided into a number of large and small plates and the plates are floating on the mantle Plate Tectonics Theory

7. Lithosphere = the Earth’s crust plus the upper portion of the mantle layer

9. Earth’s Structure by Brainpop

12. Plate motion based on The Global Positioning System (GPS)

14. Plate Boundaries Divergent boundary: oPlates are moving away from each other oMidocean ridges are created and new ocean floor plates are created

15. Plate Boundaries Divergent boundary:

17. Leif the Lucky Bridge Bridge between continents in Reykjanes peninsula, southwest Iceland across the Alfagja rift valley, the boundary of the Eurasian and North American continental tectonic plates.

18.  Convergent Boundary  Convergent Boundary: plates are moving toward each other and are colliding (3 types)

19. Create subduction zones, Trenches Create near coast volcanoesCreate near coast volcanoes When Ocean Plates collide with Continental Plates

20. Benioff shear zones (a pattern of earthquakes as an ocean plate grinds down the underneath side of a continent ) When Ocean Plates collide with Continental Plates

22. When ocean plates collide with other ocean plates Island arcs are created (a pattern of volcanic islands created from a subduction zone that is located off the coast)

25. What About Hawaii? Do you see any plate boundaries there?? Hawaii

26. What About Hawaii? HOT SPOTSHawaiian Volcanoes form from HOT SPOTS (places where the mantle is hotter than others…we’re not sure why)(places where the mantle is hotter than others…we’re not sure why)

27. MountainrangesMountain ranges are created (example: Himalayan Mountains) When a continental plate collides with another continental plate

28. Himalayan Mountains Mountains 2:46

29. Transform Fault Boundary  Plates are neither moving toward nor away from each other, they are moving past one another.

30. Transform Fault Boundary San Andreas Fault  The plates may move in opposite directions or in the same directions but at different rates and frequent earthquakes are created (example: San Andreas Fault)

31. San Andreas Fault

32. NOTE: oPlates are destroyed as fast as they are created (2 ways) oPlates may be subducted and melted or may push be pushed upward to form mountains Why is Earth not getting bigger or smaller?

33. Boundaries Between Tectonic Plates—1:23

34. More Clips Mountain Building by the History ChannelMountain Building

35. How can Oreos model the plate boundaries? Very carefully, take just the top cookie off the Oreo. Break the top cookie into 2 equal halves. Replace the cookie halves back on the Oreo Using the cookie, transform Demonstrate a transform fault boundary divergent Demonstrate a divergent plate boundary convergent Demonstrate a convergent plate boundary

37. Learning Objectives Students will understand that the surface of Earth changes over millions of years. –Our understanding of Earth history is based on the assumption that processes we see today are similar to those that occurred in the past. (6-8 ES3A) –Thousands of layers of sedimentary rock provide evidence that allows us to determine the age of Earth’s changing surface and to estimate the age of fossils found in the rocks. (6-8 ES3B) –In most locations sedimentary rocks are in horizontal formations with the oldest layers on the bottom. However, in some locations, rock layers are folded, tipped, or even inverted, providing evidence of geologic events in the distant past. (6-8 ES3C)

39. Seafloor Spreading Theory : Ocean floors are moving like broad conveyor belts

40. New ocean floor crust is being created at the midocean ridges

41. Convection currents within the mantle  The up-welling leg of the current creates a divergent boundary which produces midocean ridges What causes this?

43. Convection Currents

44. Convection Current Demo

45.  The down-welling leg of the current creates one type of convergent boundary that results in trenches and a subduction zone

47. oMidocean ridges are warmer than surrounding ocean floors oActive volcanoes on ridges, earthquakes on ridges oMidocean ridge rocks are younger than surrounding ocean floor rocks oMidocean ridge volcanoes are younger than volcanoes further away What evidence do we have to support this idea?

48. THICKER oOcean floor sediments are THINNER on the ridges and get THICKER as the distance from the ridges increase oPolar reversal magnetism oPolar reversal magnetism proves that the ocean floor is moving away from the ridges What evidence do we have to support this idea?

50. Polar Reversal Magnetism Magnetic PolesMagnetic Field Reversals—2:54

51. 2-3  Atlantic Ocean – 2-3 cm/year 15-18  South Pacific Ocean – 15-18 cm/year Speed of Spreading

52. The Seafloor is Spreading Clip—4:01Seafloor is Spreading How Earth’s Structure Affects Plate Tectonics—5:43 Seafloor Spreading

53. Distribution of Volcanoes & Earthquakes

55.  The continents have shifted their position over geologic time… Continental Drift Theory

56.  …And at one time all land masses were connected into one piece called Pangaea Continental Drift Theory 3—2:21

57. oPangaea began to split apart 200 million years ago oDiagram North America LaurasiaGreenlandEurasia Pangaea Africa West G.S.America Gondwanaland Antarctica East G.Australia India Pangaea—A History of the Continents: 2:23

58. The First Continents 4:57

59. USGS Plate Motions Clip

60. oThe continents are like packages on the seafloor conveyor belt Continents

62. oOcean floor sediments are thin on the ridges and get thicker as the distance from the ridges increase oPolar reversal magnetism away oPolar reversal magnetism proves that the ocean floor is moving away from the ridges What evidence do we have to support this idea?

63. oHigh percentage fit of continents at the 500 fathom level Evidence

64. oMinerals, fossils, and mountains on now different continents match if the continents were together Evidence The Mystery of Brachiosaurus (~3 min)

66. oGlaciation patterns indicate a common ice cap at the South Pole Evidence

67. oPaleomagnetism oPaleomagnetism (magnetism of old rocks) indicate a common pole if the continents were all connected Evidence

69. Bill Nye’s Great 100: Plate Tectonics 2 –4:22Plate Tectonics 2 –4:22

70. Plate Tectonics by Brainpop 1)What can be found underneath Earth’s plates? 2) What kind of boundary involves two plates moving toward each other? 3) What process can explain why we see fossils of the same prehistoric animals on DIFFERENT continents?

71. Pacific Ring of Fire