Earth's History Review

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Across
  1. 5. describes the order in which fossils were formed, compared to each other
  2. 8. fossils used to determine relative age
  3. 10. any fossil that is not of the organism itself
  4. 13. movement in the mantle responsible for the movement of the crust
  5. 15. two-dimensional fossil, usually formed from soft-bodied organisms
  6. 18. fossilized imprints; hollow
  7. 19. the amount of time it takes for half of the radioactive elements to decay
  8. 20. three-dimensional fossils; filled in molds
  9. 21. the oldest layers of rock are found at the bottom
  10. 22. the supercontinent that Wegner predicted
  11. 23. fossils of an organism with little or no change
  12. 24. two plates slipping past each other
  13. 25. describes the amount of time since a rock or fossil was formed
Down
  1. 1. fossils formed when minerals replace the organism, but the original structure is maintained
  2. 2. two plates moving apart
  3. 3. two plates colliding
  4. 4. the plate around which you can find the Ring of Fire
  5. 6. a gap in the geologic record
  6. 7. a layer of cooled lava that becomes part of the rock layer
  7. 9. scientist who studies the history of life on Earth through the fossil record
  8. 11. method to determing the age of fossils up to 60,000 years
  9. 12. location of 90% of earthquakes and 75% of active volcanoes
  10. 14. the element that carbon-14 decays into
  11. 16. an element that is unstable, and breaks down over time
  12. 17. a collection of cooled magma that does not reach the surface, but becomes a part of the rock layer