Across
- 4. First glaciers formed
- 5. Age of a rock layer compared to another
- 6. dead animal made into stone
- 9. Earth crust cooled
- 10. In the middle of era with dinosaurs
Down
- 1. rocks are older when they're deeper
- 2. age in yrs from fossils or radiation
- 3. 50% life of a radioactive material
- 7. Chaotic earth condition
- 8. 66 million yrs ago to today