Geologic Time

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Across
  1. 4. small events within periods
  2. 5. widely distributed and around for a short period of time
  3. 7. atoms of one element breakdown to form another
  4. 9. a gap in the geologic record
  5. 10. evidence of activities of ancient organisms
  6. 12. type of fossil where minerals have replaced organic material
  7. 16. described as older or younger
  8. 17. preserves delicate features on rocks
  9. 18. preserved remains
Down
  1. 1. division of eras
  2. 2. solid fossil created by a mold
  3. 3. hollow area shaped like an organism
  4. 6. large units of time
  5. 8. how long an item has been around
  6. 11. magma that reaches the surface and cools
  7. 13. magma that cools within the crust
  8. 14. a break in the earths's crust
  9. 15. time it takes for half the radioactive material to decay into stable material