Across
- 2. Study of rock layers and layering.
- 6. Era that saw the rise of mammals and humans.
- 8. Division of time smaller than an eon but larger than a period.
- 10. Fossilized tree resin that sometimes preserves insects.
- 11. The largest unit of geological time.
- 13. A subdivision of a period.
- 14. A gap in the geological record caused by erosion or non-deposition.
- 18. Period that ended with Earth’s largest mass extinction.
- 19. Fossil used to identify and correlate specific geologic periods.
- 20. Remains or impressions of ancient life preserved in rock.
Down
- 1. Layers of sedimentary rock that record Earth’s history.
- 3. Time required for half of a radioactive isotope to decay.
- 4. Process of crustal movement shaping Earth’s surface over time.
- 5. A time when global temperatures dropped and glaciers expanded.
- 7. Type of dating based on radioactive decay.
- 9. Science of determining the age of rocks and fossils.
- 12. Study of ancient life through fossils.
- 15. Period marked by a sudden explosion of life forms.
- 16. Era known for the dominance of dinosaurs.
- 17. The permanent disappearance of a species.