geologic time vocab

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Across
  1. 4. fossils that existed for a short period of time across many regions
  2. 5. the law of _____________ that states that the rock closest to the top is the youngest rock
  3. 7. the age of something COMPARED to something else
  4. 9. a very long period in time, like the hadean ___
  5. 10. crucial animals for creating oxygen in early earth
Down
  1. 1. the time it takes for 1/2 of an unstable element to change into a stable one
  2. 2. when a rock cuts across another rock
  3. 3. the exact age of something
  4. 6. when a rock is inside another rock
  5. 8. true or fake: an intrusion is younger than the rocks around it