Geological Puzzle

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Across
  1. 1. Age of reptiles
  2. 4. Formulated the theory of continental drift
  3. 5. Age of Fish
  4. 9. Formed when hot, molten rock crystallizes and solidifies
  5. 10. Used for long radioactive dating
  6. 13. Age of mammals
  7. 17. Process where elements break down
  8. 18. States that rocks on top are younger than rocks on the bottom
  9. 19. Used for short radioactive dating
  10. 20. 260 million years ago
  11. 21. Information about an organism's life
  12. 23. Single-celled organisms began
Down
  1. 1. When 50% of the species die out in a relatively short period of time
  2. 2. 225 million years ago
  3. 3. Early fish didn't have them
  4. 4. Hard-shelled animals that lived in shallow seas
  5. 6. Only found on asteroids
  6. 7. First small dinosaurs appeared
  7. 8. Where new rock meets up with much older rocks
  8. 11. Formed when rocks are subjected to high heat and high pressure
  9. 12. The rate of radioactive decay
  10. 14. A theory of the creation of the universe
  11. 15. End of cretaceous, 65 MYA
  12. 16. Formed when rocks lay on top of each other to form layers
  13. 22. One of the first hominin fossils found