Across
- 2. Era with more complex life forms and dinosaurs
- 6. When older rock is surrounded by younger rock
- 7. Second time chunk (Mesozoic)
- 8. When species die off
- 9. When younger rock cuts across older rock
- 12. Era when Pangaea formed,life developed
- 13. Fourth time chunk (Holocene)
Down
- 1. Earth's geological history
- 3. Era with large mammals and humans
- 4. A rock layer is older or younger than another rock layer
- 5. Largest time chunk
- 10. Dating rock by the decay of radioactive isotope
- 11. Third time chunk (Jurassic)
- 12. Eon that marks Earth's beginning