Geologic time

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Across
  1. 4. Ice age occurs in this time period
  2. 5. Age of the fishes
  3. 6. Period in which Pangea forms
  4. 8. Salt flats
  5. 11. Swimming reptiles
  6. 13. Index fossil that becomes extinct
  7. 14. Oldest rock formation
  8. 15. present day era of life
  9. 17. Age of the dinosaurs
  10. 19. Himalayan mountains form in this time
  11. 20. Period when the rocky mountains form
Down
  1. 1. Mats of algae
  2. 2. First birds
  3. 3. Organism without a backbone
  4. 7. Era that begins with the Cambrian period
  5. 9. Time period in which Pangea broke up
  6. 10. An exposed layer of craton
  7. 12. Animals with out of water proof covering
  8. 16. Example of a single cellular organism
  9. 18. example of a multicellular organism