Plate Tectonics

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  1. 4. Zone the process by which one tectonic plate sinks below another, returning to the mantle, where the rock is re-melted. Subduction takes place at convergent plate boundaries. Oceanic crust, which is denser, will always subduct under the less dense continental crust. It is also the process in which slab pull occurs.
  2. 8. Waves vibrations that travel through Earth carrying the energy released during an earthquake
  3. 10. Crust thinner, more dense,mostly basalt younger crust making ocean floor
  4. 12. Crust Thicker, less dense, mostly granite, older crust that makes up the continents
  5. 14. Push a tectonic process associated with convection currents in Earth's mantle that occurs when the weight of an elevated ridge pushes an oceanic plate towards a subduction zone
  6. 16. a German meteorologist and geophysicist who originated the theory of continental drift.
  7. 17. the single huge super continent that existed about 200 million years ago, when all of Earth's continents were joined together.
  8. 20. A dark, dense, igneous rock with a fine texture, found in oceanic crust
  9. 21. Boundary where two tectonic plates move away from each other.
  10. 22. of Plate Tectonics the theory that Earth's lithosphere is broken into enormous slabs, or plates, that are in motion. Scientists use the theory of plate tectonics to explain how Earth's continents drift.
  11. 23. Maps imaginary line on a map that shows points of the same age; formed at the same time
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  1. 1. Current the convection currents in the mantle that occur because hot rock in the lower part of the mantle is less dense and rises, and cooler rock in the upper part of the mantle cools, becomes more dense, and sinks. Mantle convection is thought to be the mechanism driving the movement of tectonic plates.
  2. 2. Canadian Scientist who developed Theory of Plate Tectonics
  3. 3. Ridge a chain of mountains on the ocean floor. New ocean floor forms at the mid-ocean ridge where the seafloor is spreading and ridge push is initiated.
  4. 5. an area around the Pacific Ocean where 75% of active and dormant volcanoes are located and 90% of earthquakes occur
  5. 6. Valley a deep valley caused by the rifting (splitting) of a continental tectonic plate. The East African Rift Valley is an example of continental rifting in progress.
  6. 7. Ocean Trench a deep valley along the ocean floor beneath which oceanic crust slowly sinks toward the mantle.
  7. 9. Boundary where two tectonic plates move toward each other.
  8. 11. Reversal the switching or changing of Earth's magnetic poles such that the north magnetic pole becomes located at the south magnetic pole's position and vice-versa. Scientists have found evidence of magnetic reversals in layers of rock along the ocean floor.
  9. 13. A usually light colored igneous rock that is found in continental crust
  10. 15. Spreading the process by which new oceanic crust is formed when magma rises up through fissures and solidifies at the mid-ocean ridges and thus pushing the older, adjacent seafloor towards trenches. This is why the age of the sea floor increases with distance away from the mid-ocean ridges.
  11. 18. Hess an American geologist who studied mid-ocean ridges using echo-sounding surveys of the Pacific and ultimately developed the theory of sea-floor spreading.
  12. 19. Boundary where two tectonic plates slip past each other, moving in opposite directions.
  13. 24. Pull a convection current process that occurs at subduction zones when a denser tectonic plate sinks into the asthenosphere and "pulls" the trailing lithosphere along.