Across
- 2. Lots of this gas was present in the Hadean Eon
- 5. Word to describe the land during the Paleozoic Era
- 7. Versions of elements used to see how old a rock is
- 9. First Eon, oceans of fire
- 11. Fifth Era, Pangea broke apart & age of reptiles
- 13. How we know how old the Earth is
- 14. Reptiles that lived during the Mesozoic Era
- 15. Location of asteroid that hit Earth, killing all dinosaurs :(
- 16. Most recent supercontinent
Down
- 1. Essential life process started by unicellular organisms in the Proterozoic Eon
- 3. Third Eon, basic life started & supercontinents formed
- 4. When a large amount of life dies out at the same time
- 6. Fourth Era, explosion of life that was huge
- 8. Sixth Era, current era & human life started
- 10. Second Eon, asteroids hitting Earth brought 1/2 of water
- 12. Surface of the Earth during the Archean Eon