A Trip Through Geologic Time

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Across
  1. 2. a solid copy of the shape of an organism
  2. 5. age of a rock when compared to other rocks
  3. 9. the process by which all the different kinds of living things have changed over long periods of time
  4. 11. one of the units of geologic time into which geologists divide eras
  5. 17. states that the oldest layer is at the bottom in an undisturbed horizontal layer of sedmintary rocks
  6. 19. the atoms of one element break down to form atoms of another element
  7. 21. the surface where new rock layers meet a much older rock surface beneath due to erosion
  8. 22. hollow area in a sediment in the shape of an organism
  9. 23. a fossil that is widely distributed and only existed a short period of geological time
Down
  1. 1. scientist who studies fossils
  2. 3. provides evidence of the activities of ancient organisms
  3. 4. extremely thin coating of carbon on rock that preserves delicate parts of plant or insect
  4. 6. a break in the Earth's crust
  5. 7. a record of the geologic events and the evolution of life
  6. 8. remains of organisms in tar, amber, or ice
  7. 10. one of three long units of geologic time between the Precambrian and the present
  8. 12. magma that cools and hardens within a rock layer
  9. 13. lava that hardens on the surface and forms igneous rock
  10. 14. fossils in which minerals replace all or part of an organism
  11. 15. the number of years that have passed since a rock formed
  12. 16. preserved remains or traces of living things
  13. 18. the time it takes for half of the radioactive atoms to decay
  14. 20. refers to any species that longer exists on Earth