test review

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Across
  1. 3. earth's crust forms
  2. 5. Life multiplies and radiates, largest proliferation in earth's history
  3. 8. Earth's oxygen forms for the first time
  4. 9. modern humans/agriculture appears
  5. 10. a period that is divided into two shorter periods where hominids appear
Down
  1. 1. most oxygen in earth's history
  2. 2. largest extinction of the 5
  3. 4. jawless fish
  4. 5. this period ended the dinosaurs by a meteor strike
  5. 6. age of dinosaurs
  6. 7. eon where multicellular organisms appear