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Flashcards

Plate tectonics

Fonsy Moreno Exámenes 4º ESO Ciencias Naturales Spanish 68 cards

Cards in this deck (68)

  1. 1What does continental drift purposes?That Earth's continents had once been joned as a single landmass that broke apart and sent the continents adrift
  2. 2When did Alfred Wegener presented his ideas?1912
  3. 3What were his ideas about?Continental movement
  4. 4How was called the idea that Wegener had developed?Continental drift
  5. 5How do Wegener called the supercontinent of his hypothesis?Pangaea
  6. 6When did Pangaea started to break apart?200 mya
  7. 7Since 200 mya, the continents......have continued to slowly move to their present positions
  8. 8Wegener was the first man to do... what exactly?To base his ideas on more than just the puzzlelike fit of continental coastlines on both sides of the Atlantic Ocean.
  9. 9What did he also do to support his hypothesis?He collected and organizated rocks, climate and fossiles data.
  10. 10Wegener reasoned that when Pangaea break apart,......large geological structures fractured as the continents separated.
  11. 11What did Wegener think about some kind of rocks?That there should be areas of similar rock types on opposite sides of the Atlantic Ocean
  12. 12Why did rocks help Wegener?Beacuse, as they were similar althought they were in different continentes, it could suggest Wegener's idea: that the continents had once been joined together
  13. 13Wegener took another piece of evidence from fossils. Why? (double answer)- The land-dwelling animals could not have swum the great distances that now exist between continents
    - Fossils of Mesosaurus had been found in only freshwater rocks and this spieces couldn't have crossed the oceans.
  14. 14What is peculiar in the fossil ages?That they coincide with the Wegener's time frame for the breakup of Pangaea, supporting its hypothesis
  15. 15Fossils that Wegener studied helped him to......find clues about ancient climates
  16. 16Name one fossil that helped Wegener a lot and why.Glossopteris, a seed fern that looked like low shrubs.
    Fossils of this plant have been found on many parts of Earth and Wegener said that this plant could only grow up in temperated climates, so those zones were once closer to the equator
  17. 17What are ocean ridges?Vast, underwater mountain chains running along the ocean floors around Earth
  18. 18Name the dimensions and characteristics of ocean ridges80,000 km long and up to 3 km above the ocean floor. Earthquakes and volcanism.
  19. 19What are deep-sea trenches?Narrow, enlogated depression in the seafloor
  20. 20Name the main characteristic of deep-sea trenches and give one exampleThat thy can be thousand of kilometers long and many kilometers deep. Marianas Trench (more than 11 km deep).
  21. 21The ages of the rocks that make up the seafloor......varies across the ocean floor
  22. 22What rock samples are younger: those taken near ocean ridges or near deep-sea trenches?Near ocean ridges
  23. 23The age of oceanic crust increases......with the distance from a ridge
  24. 24The oldest parts of the seafloor are geologically......young - about 180 million years old
  25. 25How thick are ocean-floor sediments? And continental?The first ones are a few hundred meters thick but the second ones areas are blanketed with 20 km thick layers of sedimentary rocks.
  26. 26What did scientists hypothesize about the ocean-floor sedimentary layer?That the relatively tiny layer of ocean sediment was related to the age of the ocean crust
  27. 27The thickness of the sediment increases......with the distance from an ocean ridge
  28. 28The patter of thickness......is symmetrical
  29. 29Earth has a magnetic field generated by...... the flow of molten iron in the outer core
  30. 30When does a magnetic reversal happen?When the flow in the outer core changes and Earth's magnetic field changes direction
  31. 31What does paleomagnetism studies?The history of Earth's magnetic field
  32. 32What happens when lava solidifies?That iron-bearing minerals, such as magnetite, crystalize and behave like tiny compasses and aign with the Earth's magnetic field
  33. 33Data taken from paleomagnetic studies......allowed scientists to construct a magnetic polarity time scale
  34. 34Oceanic crust is mosty......basaltic rock, which contain large amounts of iron-bearing minerals
  35. 35The regions with normal polarity and reversed polarity......formed a series of stripes across the floor parallel to the ocean ridges
  36. 36The ages and widths of the stripes......matched from one side of the ridges to the other
  37. 37What is seafloor spreading?The theory that explains how new ocean crust is formed at ocean ridges and destroyed at deep-sea trenches
  38. 38Explain the process of seafloor spreadingMagma, which is hotter and less dense than surrounding material, is forced toward the surface of the crust along an ocean ridge. As both sides of the ridge spread apart, the rising magma fills the gap that is created. When it solidifies, a small amount of new oceanic floor is added to the Earth's surface. As it continues, more magma is forced upwards and solidifies
  39. 39What are tectonic plates?Huge pieces of crust and rigid mantle that fit together at their edges to cover Earth's surface.
  40. 40How do this plates move?Slowly
  41. 41Plate tectonics is the theory that......describe how tectonic plates move
  42. 42Name three physical facts that all tectonic plates perform- They move in different directions
    - They move at different rates
    -They interact with one another at their boundaries
  43. 43Name the three different kind of boundaries and their peculiarities- Divergent: tectonic plates move away from each other
    - Convergent: tectonic plate move toward each other
    Transform: tectonic plates move horizontally past each other
  44. 44Where are most of divergent boundaries?Along the seafloor (ocean ridges)
  45. 45What is a rift?A fault-bounded valley
  46. 46The process of seafloor spreading......can cause an ocean basin to grow wider
  47. 47What is a rift valley? And when is it formed?A long, narrow depression. When continental crust begin to separate.
  48. 48What might happen while rifting?It could lead to the formation of a new ocean basin
  49. 49When two oceanic plates collide...... the denser plate descendes below the other in a process called subduction
  50. 50What is oceanic crust mostly made of?Minerals that are high in iron and magnesium and form dense, dark-coloured basaltic rocks as... the basalt XD
  51. 51What is continental crust mostly made of?Minerals like feldespar and quartz that form less-dense, lighted-coloured granitic rocks.
  52. 52It's an oceanic-oceanic convergent boundary when......one oceanic plate, the denser one, descends below another oceanic plate.
  53. 53What does the oceanic-oceanic convergence process creates?A (deep-sea) trench
  54. 54The subducted plate descendes into......the mantle, in order for recycling oceanic crust formed at the ocean ridge
  55. 55Water takes an important in the plate's melting. Why?Because it makes the plate's melting point to be lower
  56. 56How is the molten material called? And what happens to it?Magma. It rises back to the surface, because it is less dense, and erupts forming an arc of volcanic islands that parallel the trench.
  57. 57Give an example of a trench and its respective arc of volcanic islandsMarianas/Aleutian Trench and Marianas/Aleutian Islands
  58. 58It's an oceanic-continental convergent boundary when......an oceanic plate converges with a continental plate
  59. 59What happens to the oceanic plate in an oceanic-continental convergent boundary? And what does it produces?It is subducted. A trench and a volcanic arc
  60. 60What does oceanic-continental convergence results in?A chain of volcanoes along the edge of the continental plate, which also means a mountain range with many volcanoes
  61. 61Give an example of oceanic-continental convergent boundaryThe Peru-Chile Trench and the Andes mountain range
  62. 62It's a continental-continental convergent boundary when......two continental plates collide
  63. 63When do continental-continental convergence form?Long after an oceanic plate has converged with a continental plate
  64. 64An oceanic plate can be subducted......dragging an attached continent behind it
  65. 65Oceanic crust can descend beneath the continental crust... but why continental crust couldn't do it?Because continental rocks are less dense than oceanic ones
  66. 66So, if continental crust cannot descend beneath continental crust... what happens in a continental-continental convergent boundary? And what do they form?Both plates' edges collide and become crumpled, folded and uplifted. A vast mountain range, like the Himalayas
  67. 67Name two characteristics about transform boundariesLong faults and shallow earthquakes
  68. 68In transform boundaries, Earth's crust changes......its relative direction and velocity from one side of the boundary to the other

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Ciencias Naturales Exámenes 4º ESO (Biología y Geología 4º ESO) Flashcards on Plate tectonics, created by Fonsy Moreno on 20/10/2014.
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