Across
- 2. plates slide horizontally past each other, shear stress, deep, vertical faults between plates, “conservative” boundary, lots of shallow earthquakes
- 5. at convergent (or transform) boundary geologic activity: active tectonics – earthquakes, volcanoes, mountain building narrow continental shelves, deep trenches, rugged coasts
- 6. Mass/Volume
- 9. (subduction)
- 10. elongated depression in the seafloor, deepest places on Earth
- 13. glacial remnants (striations) in tropics, (Africa, India, Australia) tropical remnants in Arctic and Antarctic, marine remnants at high latitudes/elevations
- 16. submerged volcanic peak
- 17. “all sea” surrounded Pangaea “paleo-Pacific”
- 18. (MORs)continuous volcanic mountain ridges on seafloor
- 20. a buoyant substance is ___________ than what it is moving upwards through
- 23. cyclical opening and closing of ocean basins over geological time due to plate tectonics
- 26. the theory that Earth's continents were once joined in a single supercontinent, Pangaea, before drifting apart over millions of years
- 27. (seafloor spreading) wide ocean basin • passive margins on either side
- 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
- 33. a volcanic archipelago (chain of islands) parallel to plate boundary/trench e.g., Japan, Aleutian Islands
- 34. sediment at spreading centers
- 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!
- 36. formed when India moved northward and collided with Eurasia
- 39. basalt rocks away from spreading centers
- 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!
- 42. geology professor + WWII naval captain used hydroacoustics to map seafloor identifies MORs, trenches, guyots discovers seafloor spreading
- 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!
- 48. initial stages of continental breakup
- 50. narrow volcanic mountain range at subduction zones • e.g., Cascades, Andes
- 51. land expression of Mid Atlantic Ridge
- 52. (continental collision) mountain range
- 54. Hydrothermal vent, hotter (>350 ˚C) expel metal sulfides support chemosynthetic communities
- 56. not at plate boundary geologic activity: weathering and erosion • broad continental shelves, wide beaches, barrier islands, lots of river deposited sediment
- 57. (1880-1930) first proposed that the crust moves around (~1915)
Down
- 1. (seafloor spreading) • seawater floods in • new ocean floor forms
- 3. rocks, mountain belts, faults paleo-Appalachians: eastern US, Newfoundland, British Isles, Scandinavia
- 4. 2 continental plates collide, build large mountain chains “crustal thickening” e.g., Himalayas, Alps, Appalachians
- 7. where 2 plates meet
- 8. Fitting of Continents, Fossil Evidence, Structural Evidence, Paleo-Climates
- 11. Basalt at spreading centers
- 12. (subduction + SFS) closure and subduction on margins
- 14. Subduction Zone, oceanic crust sinks below continental crust partial melting, volcanism, trenches, continental arcs, deep earthquakes
- 15. upwards force of a substance
- 19. Temp. increase
- 21. Plate Boundary, crust thins, stretches, 2 plates move apart (diverge) “constructive” – crust is created by upwelling
- 22. magma produced and pulled up from the mantle
- 24. process where a plate is forced beneath another causes partial melting
- 25. Hydrothermal vent, hot (30-350 ˚C)
- 28. introduction of water lowers melting temperature of rock, causing melting
- 29. identical ancient fossils on separated continents, Mesosaurus – Permian (260 Ma) aquatic reptile, Lystrosaurus – Permian-Triassic (250 Ma) land reptile, Glossopteris – Permian tree fern
- 31. sediment away from spreading center
- 32. Subduction Zone, partial melting, volcanism, trenches, volcanic island arcs, deep earthquakes
- 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)
- 38. seawater absorbs substances from magma chamber and releases hot, mineral rich water
- 41. One of the flaws in Wegener's theory, the continental drift lacked a _______? Was not the tides.
- 43. formed when N. America, Africa, and Eurasia collided (480 Ma)
- 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
- 46. Temp. decrease
- 47. “all land” supercontinent that began breaking up ~200 Ma
- 49. Mexico through Colorado
- 52. One of the flaws in Wegener's theory, what was imperfectly matched
- 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!
- 55. (continental rifting)continent stretches, thins, cracks rift valley with upwelling