Geologic Time Scale

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Across
  1. 3. Amount of time it takes for half an isotope to decay
  2. 5. Estimate of how old something is
  3. 7. Fossils that are used for dating
  4. 8. relating to the period before written records
  5. 9. New layers of rock on old layers
  6. 10. States that if the rock fragments are in another rock, the rock is older
Down
  1. 1. that if a fault cuts through a rock it is younger than the rock
  2. 2. Representation of time based on the rock record of earth
  3. 4. Preserved remains of something
  4. 6. Exact age of something