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Earth Science

Earth Science. Plate Tectonics. Essential Question. What is the history of Plate Tectonics? What are the mechanisms?. Geosphere Use the plate tectonics theory to explain features of the earth’s surface and geological phenomena, and describe evidence for the plate tectonics theory.

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Earth Science

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  1. Earth Science Plate Tectonics

  2. Essential Question • What is the history of Plate Tectonics? • What are the mechanisms?

  3. Geosphere Use the plate tectonics theory to explain features of the earth’s surface and geological phenomena, and describe evidence for the plate tectonics theory.

  4. Key concepts Earth Composition Crust: The Earth’s Skin, outer layerMantle: upper part is able to flow very slowly Core: interior at high temperature and pressure

  5. starryskies.com/.../Earth/ under_the_surface.html

  6. Key concepts • Evidence of “continental drift”— • . • Physical fit of continents • Fossil evidence • Measurements of movement • Rock layer sequences • Glacial evidence Alfred Wegener

  7. What is the theory of continental drift? • the idea that the continents were once all joined together in one super-continent called Pangaea and slowly moved to their current positions

  8. http://wrgis.wr.usgs.gov/docs/parks/animate/A08.gif

  9. What evidence supports the theory of continental drift?

  10. Shoreline Fit of the Continents http://www.abdn.ac.uk/zoohons/lecture1/img008.GIF

  11. Fossil Evidence The fossils from the exact same animals are found on continents separated by vast oceans.

  12. Matching Rock Layers

  13. Glacier Evidence Glaciers scars are found on continents which are today too warm for glaciers.

  14. How fast are the plates moving?

  15. Essential Question: You may wonder… Why are the continents moving?

  16. Seafloor Spreading The oceans are widening along the mid-ocean ridges.

  17. Volcanoes located along ocean ridges erupt, creating new ocean floor.

  18. Key concepts Plates—continental crust, oceanic crust Features—faults, trenches, mid-ocean ridges, folded mountains, hot spots, volcanoes Related actions —earthquakes, volcanic activity, seafloor spreading, mountain building, convection in mantle.

  19. Three Types of Plate Boundaries • Divergent • Convergent • Transform

  20. The earth’s lithosphere is broken into huge sections called plates that are in constant motion.

  21. What are the plates made of? • Ocean plates are made of basalt. • Continental plates are made of granite.

  22. Divergent Plate Boundaries Two land or ocean plates move apart in opposite directions. Magma flows to the surface between them creating new crust.

  23. Mid-Atlantic Ridge = Divergent Boundary

  24. http://www.geo.lsa.umich.edu/~crlb/COURSES/270/Lec12/spreexamples.jpeghttp://www.geo.lsa.umich.edu/~crlb/COURSES/270/Lec12/spreexamples.jpeg

  25. Iceland – a continent directly over the Mid-Atlantic Ridge

  26. Subduction Zones • An ocean plate and a continental plate hit head-on. The ocean plate subducts under the continent forming a trench. The subducting plate melts. Magma rises to the surface creating a string of volcanic mountains parallel to the shoreline.

  27. Andes Mountains Subduction zones form chains of volcanic mountains along the shoreline.

  28. Collision Zones Two continents hit head-on, crinkling up the land into a high mountain chain.

  29. India’s Collision with Asia Himalayas

  30. The Himalayas Are Born…

  31. Island Arcs Two ocean plates hit head-on. One ocean plate is forced to subduct under the other forming an ocean trench. The subducting plate melts. Magma rises to the surface forming a string of volcanic islands parallel to the trench.

  32. The Aleutian Islands

  33. Key concepts Forces—tension, compression shearing Ask a Geologist Ask an earth scientist

  34. How does tectonic activity affect the earth’s crust? • Builds mountains • Creates deep ocean trenches • Causes earthquakes • Create volcanoes

  35. Ocean Trenches http://www.nhusd.k12.ca.us/ALVE/wow/Ocean/seafloor.gif

  36. Volcanoes

  37. Most volcanoes occur at plate boundaries…

  38. http://www.thirteen.org/savageearth/hellscrust/assets/images/ringoffire.jpghttp://www.thirteen.org/savageearth/hellscrust/assets/images/ringoffire.jpg

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