Across
- 5. Time it takes 1/2 of the atoms to decay into an isotope
- 7. Formed at a convergent boundary
- 10. In a cross-section of rock, oldest at the bottom
- 14. Approximate age
- 15. Large landmass consisting of all the continents
- 16. State of matter of the inner core
- 17. ridge Example of a divergent boundary
Down
- 1. Plates slide in opposite directions
- 2. One type of crust
- 3. Crust and upper portion of mantle
- 4. Cools to form new crust
- 6. Broadest category in geologic time scale
- 8. Actual date that object died
- 9. Full spreading rate
- 11. Third planet from the sun
- 12. Tool used to represent carbon-14
- 13. Layer of rock