Across
- 2. a type of coal mining used when the coal is located deep below the Earth's surface
- 4. a process where the inner core of an atom is split and energy is released
- 6. a fossil fuel found underground that is mostly made up of methane
- 7. a process where high-pressure water splits apart underground rocks, releasing trapped natural gas
- 8. oil; a liquid fossil fuel found in underground rock formations
Down
- 1. a type of coal mining used when the coal is located near the Earth's surface
- 3. a resource with a limited supply and that takes a long time to regenerate
- 5. the most common source of nonrenewable energy (coal, petroleum, and natural gas)