Across
- 3. A break in the geologic record
- 4. Divides Earth natural history
- 6. the time required for half a sample to break down
- 7. if an object is younger or older than others
- 9. Ordered arrangement of rock layers based on ages
- 11. radioactive isotope breaks down to stable isotope
Down
- 1. If undisturbed younger rocks lie above older rocks
- 2. remains of an organism that lived long ago
- 3. explained by current geologic processes Climate involves weather conditions
- 5. long cylinder of ice
- 7. comparing relevant percentages to get age
- 8. Method of measuring age in years
- 10. A scientific study of Earth