Chapter 7 Plate Tectonics Vocabulary

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Across
  1. 5. – A plate boundary where two tectonic plates slide horizontally past one another
  2. 9. – A change in Earth’s magnetic field in which the north magnetic pole becomes the south magnetic pole and vice versa; has occurred on average every 500,000 years over the past 65 million years
  3. 14. – The hypothesis proposed by Alfred Wegener that Earth’s continents were once joined together and later split apart and drifted
  4. 15. – The process in which two lithospheric plates of different densities converge and the denser one sinks into the mantle beneath the other
  5. 16. – A continent, such as Pangaea, consisting of all or most of Earth’s continental crust joined together in a single, large landmass
  6. 17. – The hot upper mantle rock located within a plume and associated with a volcanic center that forms on the overlying lithosphere
  7. 18. – A rising column of hot, plastic rock within the mantle
Down
  1. 1. – The undersea mountain chain that forms at the boundary between divergent tectonic plates within oceanic crust; it circles the planet like the seam on a baseball, forming Earth’s longest mountain chain
  2. 2. – The concept of balance between gravity and buoyancy that causes the lithosphere to float on the mantle at different elevations
  3. 3. – The process by which a continent is pulled apart at a divergent boundary
  4. 4. – A magnetic orientation the same as that of Earth’s current magnetic field
  5. 6. – A plate boundary where tectonic plates move apart from each other and new lithosphere is continuously forming; also called a spreading center or a rift zone
  6. 7. – The theory of global tectonics stating that the lithosphere is segmented into several plates that move relative to one another by floating on and sliding over the plastic asthenosphere
  7. 8. – The hypothesis that segments of oceanic crust are separating at the Mid-Ocean Ridge
  8. 10. – The upward and downward flow of fluid material in response to density changes produced by heating and cooling
  9. 11. – The portion of the upper mantle just beneath the lithosphere, extending from a depth of 100-350 kilometers below the surface of earth and consisting of weak, plastic rock where magma may form
  10. 12. – A plate boundary where two tectonic plates move toward each other and collide
  11. 13. – A fracture or edge that separates two tectonic plates