Across
- 2. a solid fossil fuel formed underground from partially decomposed plant material
- 4. a gaseous fossil fuel formed from the remains of buried microscopic organisms
- 6. a type of nonrenewable energy that comes from remains of plants and animals long ago
- 7. a liquid fossil fuel formed from the remains of buried microscopic organisms
- 8. general type of resource that can be replaced at the rate it is used
Down
- 1. any natural material that is used by humans
- 3. a type of nonrenewable energy that uses the nucleus of elements to release energy by either fission or fusion
- 5. general type of resource that forms at a rate much slower than it can be replaced