Geologic Time

2. the ordivician period lasted almost 45 ______ years
4. period where coral reefs first appeared
6. number of periods in the cenozoic era
11. this continent collided with North America during the devonian period
12. the era in which we currently live
14. this period during the paleozoic era refers to the deposits of coal, which is made of carbon, that began to accumulate during this time
16. these were the only rocks on Earth during the hadean time
17. did pangaea exist during the triassic period?
18. separated based on major extinctions or evolutions
19. these mountains existed between France and Switzerland and are what the Jurassic period is named for
20. number of periods in the mesozoic era

1. the cambrian _____________ refers to all of the major groups of animals that first appear at this time
3. this is the period in which we are living
5. this time includes both the proterozoic and archean eras
7. what organisms do in order to survive new or changing environments
8. this era contains both the jurassic and cretaceous periods
9. long stretch of time before the paleozoic era; we have very little information about this time
10. one of the three periods in the cenozoic era
13. these are longer than periods on the geologic time line
15. number of periods in the paleozoic era