Across
- 2. process to calculate the age of rocks
- 3. remains, imprints, or traces
- 4. era of recent life began 66 mil years ago
- 6. that forms in rock
- 7. chlorophyll containing bacteria
- 10. longest part of earths history
- 14. thin film of carbon residue
- 16. fossils in which the spaces inside are filled with minerals from groundwater
- 19. middle era of earths history
Down
- 1. process in which isotopes break down
- 5. organism with 3 lobed exoskeleton
- 8. era of ancient life
- 9. group of organisms
- 11. third longest division
- 12. the age of something compared with things
- 13. gap in the rock layer
- 14. a type of body fossil
- 15. longest subdivision
- 17. next smaller division
- 18. second largest division