Across
- 3. When a large area of land becomes developed
- 6. The rock that makes up Earth's crust
- 7. When desert-like conditions spread into new areas
- 8. The top layer of soil containing plant matter
- 9. A layer of soil containing mostly decaying animal and plant matter
- 12. A process in which warm air traps polluted air close to the Earth's surface
- 13. When a large area of trees are removed by humans
- 14. To restore an area of land to a more productive state
- 16. Something useful to humans that occurs naturally in the environment
- 17. The result of ozone and sunlight reacting near the Earth's surface
- 19. Pollutants released into the air
Down
- 1. The movement of soil or rock through water, wind, or ice
- 2. Precipitation that is much more acidic than usual
- 4. When, from a lack of nutrients, soil becomes less fertile
- 5. A substance applied to plants to add to nutrients in the soil
- 10. Man-made gasses composed of fluorine and chlorine
- 11. A layer of a form of oxygen that protects the Earth from the sun's UV rays
- 13. A period where there is less rainfall in an area than usual
- 15. A natural, radioactive gas that is a common source of indoor air pollution
- 18. A layer of soil containing decaying organisms and rock fragments