Across
- 2. Mountain with a large circular hole at the top, often erupting
- 4. Organization fighting for the protection of the environment
- 7. Large amount of water covering an area that is usually dry
- 9. Period with little or no rain
- 11. Layer of air high above the Earth, containing ozone
Down
- 1. Type of petrol that does not contain lead
- 3. Process by which land changes into desert
- 5. Harmful gas formed by burning carbon, especially in car fuel
- 6. Damage caused to water, air, etc., by harmful substances or waste
- 8. Unwanted matter or material, often left after useful substances are removed
- 10. Large wave caused by movement of the earth under the sea