full transcript

From the Ted Talk by Jean-Baptiste P. Koehl: The continents are moving. When will they collide?

Unscramble the Blue Letters


cteiotannnl difrt laid the foundation for our modern theory of pltae tectonics, which states that Earth’s crust is made of vast, jagged plates that shift over a layer of piaallrty moeltn rock called the mantle. These plates only move at rates of around 2.5 to 10 citmtreeens per year, but those iteannmcerl moevmntes spahe the planet's surface. So to determine when a new supercontinent will emerge, we need to predict where these petlas are hadeed.

One aaprpoch here is to look at how they’ve moved in the past. Geologists can trace the position of continents over time by measuring changes in Earth’s magnetic field. When molten rock cools, its magnetic mernlais are “frozen” at a specific point in time. So by calculating the direction and intensity of a given rock’s magnetic field, we can discover the latitude at which it was located at the time of coinlog. But this approach has serious limitations. For one thing, a rock’s magnetic field doesn’t tell us the plate’s longitude, and the lutitade measurement could be either north or south. Worse still, this magnetic data gets erased when the rock is reheated, like during continental collisions or volcanic activity. So geologists need to employ other methods to reconstruct the continents’ positions. Dating local fossils and comparing them to the global fossil record can help identifying previously connected regions. The same is true of cracks and other deformations in the Earth's crust, which can sometimes be traced across plates.

Open Cloze


___________ _____ laid the foundation for our modern theory of _____ tectonics, which states that Earth’s crust is made of vast, jagged plates that shift over a layer of _________ ______ rock called the mantle. These plates only move at rates of around 2.5 to 10 ___________ per year, but those ___________ _________ _____ the planet's surface. So to determine when a new supercontinent will emerge, we need to predict where these ______ are ______.

One ________ here is to look at how they’ve moved in the past. Geologists can trace the position of continents over time by measuring changes in Earth’s magnetic field. When molten rock cools, its magnetic ________ are “frozen” at a specific point in time. So by calculating the direction and intensity of a given rock’s magnetic field, we can discover the latitude at which it was located at the time of _______. But this approach has serious limitations. For one thing, a rock’s magnetic field doesn’t tell us the plate’s longitude, and the ________ measurement could be either north or south. Worse still, this magnetic data gets erased when the rock is reheated, like during continental collisions or volcanic activity. So geologists need to employ other methods to reconstruct the continents’ positions. Dating local fossils and comparing them to the global fossil record can help identifying previously connected regions. The same is true of cracks and other deformations in the Earth's crust, which can sometimes be traced across plates.

Solution


  1. minerals
  2. centimeters
  3. partially
  4. drift
  5. plate
  6. incremental
  7. headed
  8. approach
  9. cooling
  10. shape
  11. plates
  12. continental
  13. movements
  14. molten
  15. latitude

Original Text


Continental Drift laid the foundation for our modern theory of plate tectonics, which states that Earth’s crust is made of vast, jagged plates that shift over a layer of partially molten rock called the mantle. These plates only move at rates of around 2.5 to 10 centimeters per year, but those incremental movements shape the planet's surface. So to determine when a new supercontinent will emerge, we need to predict where these plates are headed.

One approach here is to look at how they’ve moved in the past. Geologists can trace the position of continents over time by measuring changes in Earth’s magnetic field. When molten rock cools, its magnetic minerals are “frozen” at a specific point in time. So by calculating the direction and intensity of a given rock’s magnetic field, we can discover the latitude at which it was located at the time of cooling. But this approach has serious limitations. For one thing, a rock’s magnetic field doesn’t tell us the plate’s longitude, and the latitude measurement could be either north or south. Worse still, this magnetic data gets erased when the rock is reheated, like during continental collisions or volcanic activity. So geologists need to employ other methods to reconstruct the continents’ positions. Dating local fossils and comparing them to the global fossil record can help identifying previously connected regions. The same is true of cracks and other deformations in the Earth's crust, which can sometimes be traced across plates.

Frequently Occurring Word Combinations


ngrams of length 2

collocation frequency
million years 4
continental drift 2
molten rock 2
magnetic field 2
continental collisions 2
volcanic activity 2


Important Words


  1. activity
  2. approach
  3. calculating
  4. called
  5. centimeters
  6. collisions
  7. comparing
  8. connected
  9. continental
  10. continents
  11. cooling
  12. cools
  13. cracks
  14. crust
  15. data
  16. dating
  17. deformations
  18. determine
  19. direction
  20. discover
  21. drift
  22. emerge
  23. employ
  24. erased
  25. field
  26. fossil
  27. fossils
  28. foundation
  29. geologists
  30. global
  31. headed
  32. identifying
  33. incremental
  34. intensity
  35. jagged
  36. laid
  37. latitude
  38. layer
  39. limitations
  40. local
  41. located
  42. longitude
  43. magnetic
  44. mantle
  45. measurement
  46. measuring
  47. methods
  48. minerals
  49. modern
  50. molten
  51. move
  52. moved
  53. movements
  54. north
  55. partially
  56. plate
  57. plates
  58. point
  59. position
  60. positions
  61. predict
  62. previously
  63. rates
  64. reconstruct
  65. record
  66. regions
  67. reheated
  68. rock
  69. shape
  70. shift
  71. south
  72. specific
  73. states
  74. supercontinent
  75. surface
  76. tectonics
  77. theory
  78. time
  79. trace
  80. traced
  81. true
  82. vast
  83. volcanic
  84. worse
  85. year