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Plate Tectonics

Plate Tectonics. Liz LaRosa for use with my 5 th Grade Science Class http://www.middleschoolscience.com 2009 . Earth’s Layers. The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed.

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Plate Tectonics

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  1. Plate Tectonics Liz LaRosa for use with my 5th Grade Science Class http://www.middleschoolscience.com 2009

  2. Earth’s Layers The Earth's rocky outer crust solidified billions of years ago, soon after the Earth formed. This crust is not a solid shell; it is broken up into huge, thick plates that drift atop the soft, underlying mantle.

  3. The Crust • Outermost layer • 5 – 100 km thick • Made of Oxygen, Silicon, Aluminum

  4. The Mantle • Layer of Earth between the crust and the core • Contains most of the Earth’s mass • Has more magnesium and less aluminum and silicon than the crust • Is denser than the crust

  5. The Core • Below the mantle and to the center of the Earth • Believed to be mostly Iron, smaller amounts of Nickel, almost no Oxygen, Silicon, Aluminum, or Magnesium earth's layers

  6. Tectonic Plates

  7. 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 plate tectonics

  8. 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 continental drift http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml

  9. Evidence of Pangea

  10. Sea Floor Spreading

  11. 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 sea floor spreading

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

  13. Different Types of Boundaries plate boundaries http://pubs.usgs.gov/gip/dynamic/understanding.html

  14. Divergent Boundary • Plates move apart • Constructive plate boundaries – where new oceanic lithosphere is created • Forms oceanic ridges in oceans • Forms rift vallies in continents

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

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

  17. Divergent Boundary - Oceanic Oceanic ridge http://www.geology.com

  18. Divergent Boundary - Continental Rift vally http://www.geology.com

  19. Convergent boundary • Destructive plate margins • Leading edge of one plate is bend downward and slides beneath the other • subduction zones are where one oceanic plate slides beneath a second plate

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

  21. Convergent Boundary – Oceanic & Continental Oceanic plate is more dense and sinks below the continental plate which is less dense and floats on top. Denser oceanic plate sinks to asthenosphere and begins to melt. Magma is less dense than surrounding rock and rises, sometimes causing volcanic eruptions. http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  22. Convergent Boundaries - Continental Continental lithosphere is buoyant and doesn’t sink to great depth. Complex mountain ranges are formed. Appalachian, Alps, Himalayas, and other mountain ranges were formed this way. http://pubs.usgs.gov/gip/dynamic/understanding.html & http://www.geology.com

  23. Convergent plates - oceanic • One plate sinks beneath the other causing volcanic activity similar to oceanic – continental plate margins • Volcanic island arcs are newly formed land masses forming arc shaped volcanic islands.

  24. Transform boundary • Plates grind past each other without destroying the lithosphere • Most are located within ocean basins. • A few, like the San Andres Fault, cut through continental crust

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

  26. Slab Pull • Slab pull- old oceanic crust, which is cool and dense, has sunk under another plate into the asthenosphere which pulls the trailing lithosphere along.

  27. Ridge Push • Ridge push- results from elevated oceanic ridge system and causes oceanic lithosphere to slide down the sides of oceanic ridge.

  28. Convection • Hot plumes of rock are flowing upward in mantle convection. • Hot plumes sometimes show themselves on earth’s surface as hot spots and volcanoes.

  29. Review • Name the 3 main layers of the Earth • What is a tectonic plate? • What was Pangea? • What is Sea-Floor spreading? • Name the three different types of plate boundaries and one location on Earth for each one

  30. Resources • This powerpoint was adopted from middleschoolscience.com by Ms. Glass on 9/07/12 • Video clips were found on youtube and incorporated

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