Across
- 3. process that produces oxygen and removes carbon dioxide
- 4. major events causing loss of species and impacting earth's systems
- 10. change in earth's climate affecting its systems
- 12. pressure from growing planet causes temperature rise
- 13. multi-celled organisms evolved into animals with specialized organs
- 15. plants began to inhabit land approximately 470 million years ago
- 17. more complex cells with a nucleus that emerged after bacteria
- 18. gradual breakdown of rocks and redistribution of components
- 19. period of time when earth was a molten ball of rock
- 22. protective layer in the stratosphere formed by oxygen molecules
- 23. continuous circulation of water betweenatmosphere, oceans, and land
Down
- 1. release of gases from molten earth's surface
- 2. deep-sea hot springs releasing nutrients for early life forms
- 5. movement of earth's plates allowing water circulation and formation of topographical features
- 6. earliest bacteria that emerged 3.5 billion years ago
- 7. periodic glaciations impacting sea levels,currents,and stmospheres
- 8. intense heat from frequent asteroid impact
- 9. process that consumes oxygen and releases carbon dioxide
- 11. formation of solid foundation of earth's lithosphere from cooling molten rock
- 14. process ensuring survival of the fittest organisms throughout evolution
- 16. release of heat from decaying radioactive elements
- 20. process of water vapor turning back into water
- 21. comets containing ice collided with earths, melting upon impact