Across
- 3. a fossil fuel that is easy to use with little pollution
- 5. brown soil made up of sand, silt, clay, & organic matter
- 6. resources that can be replaced
- 8. natural fuels formed long ago from the remains of living organisms
- 9. resources that can not be replaced
- 11. the number of people in an area per square mile of land
Down
- 1. raw materials that exist in a natural state on earth
- 2. a fossil fuel that can be refined into crude oil
- 4. useful substances found in the earth that are not made from plant and animal remains
- 7. hard coal
- 10. soft coal