Across
- 5. something that is tough
- 6. a precious stone
- 8. a dark natural glass
- 9. a very light and porous volcanic rock
- 10. a science that deals with the history of earth
- 13. the natural and physical attributes of land
- 15. an opening in the Earth's crust
- 17. rocks that came from inside the earth
- 18. a dark fine-grained volcanic rock
Down
- 1. the remains or impression of a plant or animal granite
- 2. pieces of bigger rocks
- 3. a metamorphic rock made of recrystallized carbon mineral
- 4. rock that is formed chiefly organic remains
- 7. between the core and the crust
- 11. transformation of a pre-existing rock
- 12. molten rock material under the Earth's crust
- 14. the outermost layer of a planet
- 16. a large natural elevation of the earth's surface