Natural Cycles and Geologic Time

2. When industries grow in a region or country, often leading to more pollution.
3. Nutrients Substances organisms need to live and grow, but can't make themselves.
5. The process by which nitrates are converted back into nitrogen gas by bacteria, returning nitrogen to the atmosphere.
7. A timeline dividing Earth's history into different periods.
11. When plants release water vapor into the air through their leaves.
14. Cycle The process by which carbon moves between living organisms, the atmosphere, oceans, and Earth's crust.
15. Water located beneath the Earth's surface in soil pore spaces and in the fractures of rock formations.
17. The process by which organic matter breaks down into simpler substances, releasing nutrients back into the environment.
19. The way plants use sunlight to make food and oxygen.
20. Layers of rock or soil in the ground.
21. When water, ice, or wind move soil and rock from one place to another.
22. Water from precipitation that flows over the surface of the ground, often carrying pollutants.
23. Fuels Energy sources like coal, oil, and natural gas formed from ancient plants and animals.

1. When water vapor turns into liquid water, forming clouds.
4. When bacteria in soil turn ammonia into nitrates that plants can use.
6. When special bacteria change nitrogen gas from the air into a form plants can use.
8. Everything around a living thing, including air, water, and land.
9. A substance found in all living things and in the air, water, and soil.
10. A gas in the air that all living things need to grow.
12. Rain, snow, sleet, or hail that falls from the sky.
13. The layer of air surrounding Earth.
16. The process of breathing out carbon dioxide, which is part of the carbon cycle.
18. When water turns into vapor and goes up into the air.