geologic time scale

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Across
  1. 2. any piece of rock that has become included in another rock
  2. 5. calendar of events in earths history
  3. 6. a fossil which is useful for dating
  4. 8. unstable atomic nucleus looses energy by radiation
  5. 9. determining an age on a specific time scale
  6. 10. a geologic feature must be younger than any rock across which it cuts
Down
  1. 1. a geographical age starting with the presence of humans
  2. 3. law of geochronology
  3. 4. a layer of material, naturally or artificially formed
  4. 7. determining the relative order of past events