radioactive dating

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Across
  1. 3. exact age
  2. 6. broken super continent
  3. 8. fraction of value
  4. 9. very icy time period
  5. 10. large star
  6. 12. formation of atoms
  7. 18. large land mass
Down
  1. 1. star death
  2. 2. estimated age
  3. 4. lots of ice
  4. 5. light shift
  5. 7. large expansion
  6. 11. 2 or more atoms
  7. 13. a fixed point in time
  8. 14. long time
  9. 15. death
  10. 16. dinosaurs
  11. 17. weather changing for a long time