Geologic Time

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Across
  1. 3. breaking down of unstable radioactive isotopes into other stable isotopes
  2. 6. how sedimentary rock is formed
  3. 8. the radioactive isotope before it decays
  4. 11. determining the actual age of an event or object in years
  5. 12. widespread lived for a short period abundant
  6. 13. include tracks, burrows, and even animal dung called coprolite
  7. 14. finding the absolute age by determining the relative percentages of radioactive parent and stable daughter isotopes
Down
  1. 1. the stable isotope after it decays
  2. 2. type of rock where fossils are formed
  3. 4. geologic process what happened in the past can be explained by the current processes
  4. 5. states that younger rock layers lie about the older rock layers if they layers have not been distrubed
  5. 7. determining whether an object or event is older or younger than other objects or events
  6. 9. traces or remains of organisms that lived long ago
  7. 10. time needed for half of a radioactive element to undergo decay