Geologic Time

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Across
  1. 1. A branch of science that focuses on Earth's crust and the history that shaped it
  2. 5. Made up of unstable atoms which give off atomic radiation
  3. 8. Older rocks on bottom newer on top
  4. 9. An organism that lived long ago
  5. 10. Exact age of a rock/fossil
Down
  1. 2. a single cell life form
  2. 3. people who study geology
  3. 4. How long it takes for half of something to decay into another thing
  4. 6. Half life is 5,730 years
  5. 7. The age of something compared to another