Early Earth

4. type of time scale that European geologists created
12. mountain-building episodes
13. dissolved the soluble minerals at Earth's surface
15. period named for the Jura mountains in France and Switzerland
16. era that means middle life; age of reptiles
18. increased oxygen gas levels in the beginning of the Proterozoic
20. Cycle where continents will come together to create a supercontinent ever 500 million years
22. means before complex life

1. carbon or mineral-rich objects that bombarded Earth's surface
2. a process that cyanobacteria used to produce nutrients needed to survive
3. provides protection from harmful ultraviolet radiation
5. era means old life
6. "ancient"; eon regarding the formation of the Earth
7. cannot survive without liquid water
8. eon means visible life; includes three eras
9. period since the beginning of the ice ages
10. occurs when matter changes state from a gas to a liquid
11. also called the Recent
14. iron oxides; when iron reacts with oxygen in the atmosphere
17. all of Earth's continents were once consolidated into a single landmass called
19. volcanoes releasing water vapor, carbon dioxide, nitrogen and other gases
21. era means new life; sometimes called the Age of Mammals