Geologic Time Scale

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Across
  1. 6. age of rock given in exact years
  2. 7. age of rock not given exactly
  3. 9. any feature that cuts across a sequence of rocks, is younger than everything it cuts.
  4. 10. time it takes for half of a remaining form to decay to a daughter product
Down
  1. 1. first life form believed to be on Earth
  2. 2. an undisturbed sequence of rocks, the oldest rocks are on the bottom and the youngest on the top.
  3. 3. any rock or fragment that’s included inside of another rock is older than the rock in which it is included.
  4. 4. unstable isotope o some element decay at a known rate into daughter products
  5. 5. useful for dating and correlating the strata it is found in
  6. 8. remains of organisms