Across
- 4. a natural substance, such as gold, pol
- 9. something found in nature that is useful to people
- 10. the careful use of natural resources so that they can last as long as possible
- 11. a dark brown to black carbon rich sedimentary rock
- 12. any material made by plants and animals that humans convert into energy
- 14. energy that is produced from the heat of the earth's crust
- 15. the process by which the wind is used to generate mechanical power or electricity
Down
- 1. plant life
- 2. a natural fuel such as coal, oil, or natural gas that is formed from the remains of plans and animals
- 3. a natural resource that can replace or rebuild itself
- 5. damaging or dirtying the environment
- 6. no longer in existance
- 7. energy created by the movement of water
- 8. a natural material that cannot be replace as quickly as it is used
- 13. energy produced by the sun