Geologic time

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Across
  1. 3. the time it takes for half of a radioactive element to change to another element
  2. 7. the era in which dinosaurs lived
  3. 8. Any rock fragment inside of another rock is older that the rock it is inside of
  4. 9. the law that says what is on the bottom is the oldest and what is on the top is the youngest
  5. 10. any feature that cuts across a sequence of rocks is younger than the other rocks
Down
  1. 1. the age compared to other fossils or rocks
  2. 2. the era in which many early marine animals lived
  3. 4. the exact age
  4. 5. the current era
  5. 6. a fossil used to find the relative age