Geology Midterm Part 2

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657
Across
  1. 2. plates slide horizontally past each other, shear stress, deep, vertical faults between plates, “conservative” boundary, lots of shallow earthquakes
  2. 5. at convergent (or transform) boundary geologic activity: active tectonics – earthquakes, volcanoes, mountain building narrow continental shelves, deep trenches, rugged coasts
  3. 6. Mass/Volume
  4. 9. (subduction)
  5. 10. elongated depression in the seafloor, deepest places on Earth
  6. 13. glacial remnants (striations) in tropics, (Africa, India, Australia) tropical remnants in Arctic and Antarctic, marine remnants at high latitudes/elevations
  7. 16. submerged volcanic peak
  8. 17. “all sea” surrounded Pangaea “paleo-Pacific”
  9. 18. (MORs)continuous volcanic mountain ridges on seafloor
  10. 20. a buoyant substance is ___________ than what it is moving upwards through
  11. 23. cyclical opening and closing of ocean basins over geological time due to plate tectonics
  12. 26. the theory that Earth's continents were once joined in a single supercontinent, Pangaea, before drifting apart over millions of years
  13. 27. (seafloor spreading) wide ocean basin • passive margins on either side
  14. 30. the process where tectonic forces pull continental lithosphere apart, causing it to stretch, thin, and subside, often resulting in rift valleys, earthquakes, and volcanism
  15. 33. a volcanic archipelago (chain of islands) parallel to plate boundary/trench e.g., Japan, Aleutian Islands
  16. 34. sediment at spreading centers
  17. 35. volcanism due to presence of a stationary mantle plume • lithosphere moves overhead, leaves a hot-spot track (volcanic trail) • continental & oceanic crust • indicate rate and direction of plate movement!
  18. 36. formed when India moved northward and collided with Eurasia
  19. 39. basalt rocks away from spreading centers
  20. 40. Earth’s lithospheric plates move relative to each other • because hot, mobile asthenosphere underlies cool, brittle lithosphere • movement of plates causes crustal deformation (mountains) • very slow!
  21. 42. geology professor + WWII naval captain used hydroacoustics to map seafloor identifies MORs, trenches, guyots discovers seafloor spreading
  22. 45. Type of heat transfer Formation of convection cells in mantle: 1. Heated materials expand, become less dense, rise upwards (away from heat source) 2. Materials cool, contract, become denser, fall downwards (back towards heat source) 3. Rinse and repeat!
  23. 48. initial stages of continental breakup
  24. 50. narrow volcanic mountain range at subduction zones • e.g., Cascades, Andes
  25. 51. land expression of Mid Atlantic Ridge
  26. 52. (continental collision) mountain range
  27. 54. Hydrothermal vent, hotter (>350 ˚C) expel metal sulfides support chemosynthetic communities
  28. 56. not at plate boundary geologic activity: weathering and erosion • broad continental shelves, wide beaches, barrier islands, lots of river deposited sediment
  29. 57. (1880-1930) first proposed that the crust moves around (~1915)
Down
  1. 1. (seafloor spreading) • seawater floods in • new ocean floor forms
  2. 3. rocks, mountain belts, faults paleo-Appalachians: eastern US, Newfoundland, British Isles, Scandinavia
  3. 4. 2 continental plates collide, build large mountain chains “crustal thickening” e.g., Himalayas, Alps, Appalachians
  4. 7. where 2 plates meet
  5. 8. Fitting of Continents, Fossil Evidence, Structural Evidence, Paleo-Climates
  6. 11. Basalt at spreading centers
  7. 12. (subduction + SFS) closure and subduction on margins
  8. 14. Subduction Zone, oceanic crust sinks below continental crust partial melting, volcanism, trenches, continental arcs, deep earthquakes
  9. 15. upwards force of a substance
  10. 19. Temp. increase
  11. 21. Plate Boundary, crust thins, stretches, 2 plates move apart (diverge) “constructive” – crust is created by upwelling
  12. 22. magma produced and pulled up from the mantle
  13. 24. process where a plate is forced beneath another causes partial melting
  14. 25. Hydrothermal vent, hot (30-350 ˚C)
  15. 28. introduction of water lowers melting temperature of rock, causing melting
  16. 29. identical ancient fossils on separated continents, Mesosaurus – Permian (260 Ma) aquatic reptile, Lystrosaurus – Permian-Triassic (250 Ma) land reptile, Glossopteris – Permian tree fern
  17. 31. sediment away from spreading center
  18. 32. Subduction Zone, partial melting, volcanism, trenches, volcanic island arcs, deep earthquakes
  19. 37. the study of the Earth's ancient magnetic field preserved in rocks, sediment, and archaeological materials, acting as a "fossil compass" to determine past magnetic field direction, strength, and polarity.Magnetic poles wander & reverse over time due to currents in outer core Fe in magma will “line up” with magnetic field lines and lock in place as magma solidifies Magnetic Timescale established (chrons)
  20. 38. seawater absorbs substances from magma chamber and releases hot, mineral rich water
  21. 41. One of the flaws in Wegener's theory, the continental drift lacked a _______? Was not the tides.
  22. 43. formed when N. America, Africa, and Eurasia collided (480 Ma)
  23. 44. areas of seafloor divergence and upwelling, movement of plates carries new crust away from center, very long (43k miles), 20% of Earth’s surface
  24. 46. Temp. decrease
  25. 47. “all land” supercontinent that began breaking up ~200 Ma
  26. 49. Mexico through Colorado
  27. 52. One of the flaws in Wegener's theory, what was imperfectly matched
  28. 53. Plate Boundary, crust thickens, plates move together (converge)“destructive” – crust is destroyed, The Ring of Fire, reason why no oceanic crust is > 200 Ma!
  29. 55. (continental rifting)continent stretches, thins, cracks rift valley with upwelling