Geologic Time Scale

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Across
  1. 2. Radioactive decay.
  2. 4. used to date younger rocks
  3. 7. To date older rocks
  4. 9. Some things lived before others.
  5. 10. Unless something happened,the top is younger.
Down
  1. 1. A rock inside another rock is older.
  2. 3. used to find age of rock
  3. 5. Preserved bone.
  4. 6. a rock is younger than the rock it cuts
  5. 8. Dates rocks through radio-activity.