Earth History crossword

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Across
  1. 12. The longest division of geologic time
  2. 14. the theory that the outer rigid layer of the earth is divided into a couple of dozen
  3. 17. the process of gradual change and events
  4. 19. preserved remains, impression, or trace
  5. 20. the process where organisms better adapted to their environment tend to survive
  6. 21. units of time in years
Down
  1. 1. Cenozoic,Mesozoic
  2. 2. a form of relative dating
  3. 3. first formulated in Darwin's book "On the Origin of Species"
  4. 4. chronological dating
  5. 5. The geologic age of a fossil {non specific}
  6. 6. the diversity in gene frequencies
  7. 7. various crystalline or glassy rocks
  8. 8. the changes of rocks
  9. 9. layers called beds or strata
  10. 10. forcing a body of igneous rock between existing formations
  11. 11. useful for dating and correlating the strata
  12. 13. eroded by wind, water, or other natural agents
  13. 15. The change in inherited traits over successive generations
  14. 16. a person who studies the history of life
  15. 18. the movement of magma onto the surface of the earth through volcano craters