Across
- 5. seperation of Earth's layers
- 7. Schwanz's middle name
- 8. radioactive isotopes are this.
- 10. cooled lava on the surface.
- 13. Coming together due to gravity
- 17. radioactive isotopes do this.
- 18. cooled magma underground.
- 19. Same protons. different neutrons
Down
- 1. after two, 25% parent-isotope remains
- 2. Earth's age, about 4.6...
- 3. older or younger. no number.
- 4. extension fault
- 6. intrusion rock type
- 9. law of youngest on top.
- 11. compression fault
- 12. Schwanz puts it on everything
- 14. isotope used to date once living things
- 15. second longest division: geological time.
- 16. longest division of geological time.