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Plate tectonics

Plate tectonics. Tectonic Plates. Plate Tectonics. Greek – “tektonikos” of a builder Pieces of the lithosphere that move around Each plate has a name Fit together like jigsaw puzzles Float on top of mantle similar to ice cubes in a bowl of water. Continental Drift. Alfred Wegener 1900’s

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Plate tectonics

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  1. Plate tectonics

  2. Tectonic Plates

  3. Plate Tectonics • Greek – “tektonikos” of a builder • Pieces of the lithosphere that move around • Each plate has a name • Fit together like jigsaw puzzles • Float on top of mantle similar to ice cubes in a bowl of water

  4. Continental Drift Alfred Wegener 1900’s Continents were once a single land mass that drifted apart. Fossils of the same plants and animals are found on different continents Called this supercontinent Pangea, Greek for “all Earth” 245 Million years ago Split again – Laurasia & Gondwana 180 million years ago http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml

  5. Evidence of Pangea

  6. Sea Floor Spreading

  7. Sea Floor Spreading • Mid Ocean Ridges – underwater mountain chains that run through the Earth’s Basins • Magma rises to the surface and solidifies and new crust forms • Older Crust is pushed farther away from the ridge

  8. Why do plates move?

  9. Convection currents

  10. Convection currents • What are they? • How do they make plates move? • When mantle rocks near the radioactive core are heated, they become less dense than the cooler, upper mantle rocks. These warmer rocks rise while the cooler rocks sink, creating slow, vertical currents within the mantle (these convection currents move mantle rocks only a few centimeters a year). This movement of warmer and cooler mantle rocks, in turn, creates pockets of circulation within the mantle called convection cells. The circulation of these convection cells could very well be the driving force behind the movement of tectonic plates over the athenosphere.

  11. Subduction • What is it? • One plate sinks underneath the other because it is more dense.

  12. How Plates Move http://pubs.usgs.gov/gip/dynamic/unanswered.html

  13. Convection currents

  14. Destructive vs. Constructive forces • Define both of the terms below: • Constructive forces- builds the Earth up • Destructive forces- Breaks the Earth down

  15. Destructive or constructive?

  16. Different Types of Boundaries http://pubs.usgs.gov/gip/dynamic/understanding.html

  17. Plate boundaries • Transform • Plates slide past each other • Earthquakes form

  18. Transform Boundary – San Andreas Fault www.geology.com

  19. Plate boundaries • Divergent • Plates divide • In ocean- will be mid-ocean ridges • On land- rift valleys • Why? As plates spread apart, magma rises through the gap and forms new crust

  20. Divergent Boundary – Arabian and African Plates Arabian Plate Red Sea African Plate

  21. Divergent Boundary – Iceland http://pubs.usgs.gov/gip/dynamic/understanding.html

  22. Divergent Boundary - Oceanic http://www.geology.com

  23. Divergent Boundary - Continental http://www.geology.com

  24. Convergent Boundary – Indian and Eurasian Plates Eurasian Plate Indian Plate

  25. Convergent Boundary – Oceanic & Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  26. Plate boundaries • Convergent • Plates collide (go together) • When ocean plates meet continent plates, an ocean trench forms with volcano on the land • Why? Ocean plate is more dense than continental and sinks under it into mantle (subduction)

  27. Convergent Boundary – Oceanic & Oceanic Note – plates are reversed http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  28. Plate boundaries • Convergent • Plates collide (go together) • When ocean plates meet ocean plates, an ocean trench forms with magma forming islands • Why? The ocean plate that is more dense will sink under the other (subduction)

  29. Convergent Boundaries - Continental http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  30. Plate boundaries • Convergent • Plates collide (go together) • When continent plates meet continent plates, mountains form Why? Continental plates buckle up as they push together

  31. Plate tectonic animations • http://www.nature.nps.gov/geology/usgsnps/animate/pltecan.html

  32. Additional activities: • Plate tectonics www.brainpop.com • Volcanoes http://www.brainpop.com/science/earthsystem/volcanoes/ • Earthquake http://www.brainpop.com/science/earthsystem/earthquakes/ • Pangaea activity worksheet • Plate boundary prediction worksheet

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