Plate Tectonics Notes
- 1. Earth’s Structure by Brainpop Geological Changes—3:25
- 2. Looking at the world map, what doLooking at the world map, what do you notice about the shape of theyou notice about the shape of the continents?continents? Jot down your ideas on your paper…
- 3. The thing is…the world didn’tThe thing is…the world didn’t always look like this! It used to lookalways look like this! It used to look like this:like this:
- 4. How is this possible?!?!?How is this possible?!?!?
- 5. The lithosphere is divided into a number of large and small plates and the plates are floating on the mantle Plate Tectonics TheoryPlate Tectonics Theory
- 6. Lithosphere = the Earth’s crustcrust plus the upper portion of the mantlemantle layer
- 10. Plate motion based on The Global Positioning System (GPS)
- 12. Plate BoundariesPlate Boundaries Divergent boundary:Divergent boundary: o Plates are moving away from each other o Midocean ridges are created and new ocean floor plates are created
- 13. Plate BoundariesPlate Boundaries Divergent boundary:Divergent boundary:
- 14. 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.
- 15. Convergent BoundaryConvergent Boundary: plates are moving toward each other and are colliding (3 types)
- 16. • Create subduction zones, trenches • Create near coast volcanoes • Benioff shear zones (a pattern of earthquakes as an ocean plate grinds down the underneath side of a continent) When Ocean Plates collide withWhen Ocean Plates collide with Contintental PlatesContintental Plates
- 17. Benioff Shear ZonesBenioff Shear Zones
- 19. When ocean plates collide withWhen ocean plates collide with other ocean platesother ocean plates Island arcs are created (a pattern of volcanic islands created from a subduction zone that is located off the coast)
- 22. • MountainMountain rangesranges are created • (example: Himalayan Mountains) When a continental plate collides withWhen a continental plate collides with another continental plateanother continental plate
- 24. Transform Fault BoundaryTransform Fault Boundary Plates are neither moving toward nor away from each other, they are moving past one another.
- 25. Transform Fault BoundaryTransform Fault Boundary 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)
- 26. San Andreas FaultSan Andreas Fault
- 27. o No o Plates are destroyed as fast as they are created (2 ways) o Plates may be subducted and melted or may push be pushed upward to form mountains So is the Earth getting bigger?So is the Earth getting bigger?
- 28. Boundaries Between Tectonic Plates—1:23
- 29. How can Oreos model the plate boundaries?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, Demonstrate a transform fault boundary Demonstrate a divergent plate boundary Demonstrate a convergent plate boundary
- 32. Seafloor Spreading Theory: • Ocean floors are moving like broad conveyor belts
- 33. • New ocean floor crust is being created at the midocean ridges
- 34. Convection currents within the mantle The up-welling leg of the current creates a divergent boundary which produces midocean ridges What causes this?What causes this?
- 36. The down-welling leg of the current creates one type of convergent boundary that results in trenches and a subduction zone
- 37. o Midocean ridges are warmer than surrounding ocean floors o Active volcanoes on ridges, earthquakes on ridges o Midocean ridge rocks are younger than surrounding ocean floor rocks o Midocean ridge volcanoes are younger than volcanoes further away What evidence do we have toWhat evidence do we have to support this idea?support this idea?
- 38. o Ocean floor sediments are thin on the ridges and get thicker as the distance from the ridges increase o Polar reversal magnetism proves that the ocean floor is moving away from the ridges What evidence do we have toWhat evidence do we have to support this idea?support this idea?
- 40. Polar Reversal MagnetismPolar Reversal Magnetism Magnetic Poles Magnetic Field Reversals—2:54
- 41. Atlantic Ocean – 2-32-3 cm/year South Pacific Ocean – 15-1815-18 cm/year Speed of SpreadingSpeed of Spreading
- 42. The Seafloor is Spreading Clip—4:01 How Earth’s Structure Affects Plate Tectonics—5:43 Seafloor SpreadingSeafloor Spreading
- 43. The continents have shifted their position over geologic time Continental Drift TheoryContinental Drift Theory
- 44. At one time all land masses were connected into one piece called Pangaea Continental Drift Theory 3—2:21
- 45. o Pangaea began to split apart 200 million years ago o Diagram North America Laurasia Greenland Eurasia Pangaea Africa West G. S.America Gondwanaland Antarctica East G. Australia IndiaPangaea—A History of the Continents: 2:23
- 46. The First Continents 4:57
- 47. USGS Plate Motions Clip
- 48. o The continents are like packages on the seafloor conveyor belt ContinentsContinents
- 50. o High percentage fit of continents at the 500 fathom level EvidenceEvidence
- 51. o Minerals, fossils, and mountains on now different continents match if the continents were together EvidenceEvidence The Mystery of Brachiosaurus (~3 min)
- 53. o Glaciation patterns indicate a common ice cap at the South Pole EvidenceEvidence
- 54. o PaleomagnetismPaleomagnetism (magnetism of old rocks) indicate a common pole if the continents were all connected EvidenceEvidence
- 56. Plate Tectonics 2 –4:22
- 57. Plate Tectonics by Brainpop