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Plate Tectonics

Plate Tectonics. 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 - huge, thick plates that drift atop the soft mantle. The Crust. Outermost layer 5 – 100 km thick Made of Oxygen, Silicon, Aluminum.

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Plate Tectonics

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  1. Plate Tectonics

  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 - huge, thick plates that drift atop the soft mantle.

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

  4. The Mantle • Layer between the crust and core • Contains most of the Earth’s mass • Is denser than the crust

  5. The Core • Below the mantle and to the center of the Earth • Believed to be mostly Iron

  6. Tectonic Plates

  7. Plate Tectonics • Greek – “tektonikos” means builder • Pieces of the crust/upper mantle 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

  8. Continental Drift Alfred Wegener 1900’s Continents were once a single land mass that drifted apart. Similar fossils were found on different continents. Called this supercontinent Pangea, Greek for “all Earth” 245 Million years ago http://members.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml

  9. Evidence of Pangea

  10. Pacific Ring of Fire Volcanism is mostly focused at plate margins

  11. Ring of Fire • The Ring of Fire has 452 volcanoes and is home to over 75% of the world's active and dormant volcanoes • The Ring of Fire is a direct result of plate tectonics and the movement and collisions of techtonic plates

  12. What is a volcano? • Mountain or hill • Has crater or vent in the top • Gases/Magma can escape through this vent • Size of Volcano includes material that flows down the die vent cone conduit magma chamber

  13. Types of Volcanoes • An active volcano is a volcano that has had at least one eruption during the past 10,000 years. • An erupting volcano is an active volcano that is having an eruption... • A dormant volcano is an active volcano that is not erupting, but supposed to erupt again. • An extinct volcano has not had an eruption for at least 10,000 years. Not expected to erupt again.

  14. Lava Types • Large amounts of gas and a high viscosity (sticky) magma create an explosive eruption! • Called pyroclastic eruptions • Small amounts of gas trapped magma will form a runny eruption. • Called effusive eruptions

  15. Explosive Eruptions • Sticky Magma = explosive/pyroclastic eruptions What can happen? - Ash fall • Super heated rock and ash falling from the sky • Pyroclastic flow • Lava flows; moving liquid rock, ash and gas.

  16. Pyroclastic Flow - direct impact Courtesy of www.swisseduc.ch

  17. Pyroclastic Flow - burial

  18. Pyroclastic Flow - burns

  19. From above you can see their fine grainsize and the distinctive slight ridges and grooves that show which way the mass of hot dusty air was moving.

  20. Effusive Eruptions • Runny lava eruption. • Called effusive eruptions • Effusive eruptions have fast moving lava on to the ground. Hawaii Courtesy of www.swisseduc.ch

  21. Sea Floor Spreading

  22. 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 • Soil at the Mid-Atlantic Ridge is “younger” than soil in locations further from the ridge

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

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

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

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

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

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

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

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

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

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

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

  34. 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

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