Name: _____________________________ Per.______
Date.______
Geologic Time Study Guide
1. Which choice lists the “eras” in order from earliest to most recent.
a. Cenozoic, Paleozoic, Mesozoic, Precambrian
b. Precambrian, Mesozoic, Paleozoic, Cenozoic
c. Precambrian, Paleozoic, Mesozoic, Cenozoic
2. Which era lasted for the longest time?
a. Precambrian b. Mesozoic c. Paleozoic
d. Cenozoic
3. Fill in the chart below to show the beginning and ending times for each era.
Era
Precambrian
Paleozoic
Mesozoic
Cenozoic
Begins
Ends
?
4. How does each ERA end? ________________________________
5. What makes one ERA different from another?
6. Why is it difficult to determine what conditions are “normal” for Earth?
(sentences)
7. Describe what a mass extinction is. Provide two examples of events that could
cause a mass extinction on Earth. (sentences)
Precambrian Time
8. How was Earth’s first atmosphere different from the atmosphere present today?
List specific gases.
9. What produced the first atmosphere?
10. Where did the water that made the oceans come from (2 sources)?
11. When did the first living organism appear in the fossil record? What was this
organisms like?
12. How did the arrival of photosynthetic bacteria (stromatolites) change Earth’s
atmosphere?
13. How did the arrival of photosynthetic bacteria (stromatolites) change Earth’s
climate? Explain.
14. By the end of the Precambrian, how advanced was life?
15. What was one condition preventing life from living on land during Precambrian
time?
16. What caused the mass extinction that ended Precambrian time?
Paleozoic
17. What is responsible for pulling Earth out of its SNOWBALL EARTH episode?
(Be specific).
18. What was the “Cambrian Explosion”? Describe it.
19. What change in conditions allowed life forms to live on land during the
Paleozoic?
20. What benefit does ozone provide for organisms on Earth? What molecule is
ozone made from?
21. Describe how life during the Paleozoic differed from life during Precambrian
time.
22. Most of our fossil fuels come from organic matter from this era. Describe how
coal deposits are formed? What does it form from and how does this relate to the
Paleozoic
23. The “Great Dying” is the biggest mass extinction in the fossil record. What is a
possible cause of this extinction? Describe this event.
Mesozoic
24. Describe basic climate and life forms associated with the Mesozoic.
25. Why was it so warm during the Mesozoic?
26. Pangaea broke up during this era. What causes this?
27. What are the TWO events contributed to the mass extinction of the dinosaurs.
28. What evidence supports the theory that an asteroid impact caused this extinction?
Be specific (sentences).
Cenozoic
29. How does the climate of the Cenozoic compare to that of the Mesozoic?
30. When and where did the human species evolve?
31. What may have triggered the series of ice ages that characterize the Cenozoic?
Name that “Era”
Write the name of the “era” associated with each description or development.
31.
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
44.
45.
46.
47.
48.
49.
50.
_____________________Pangaea forms
_____________________1st life
_____________________Green oceans, red skies
_____________________Dinosaur Age
_____________________Life in shallow seas
_____________________Age of Mammals
_____________________Life invades land (amphibians, land plants, reptiles,
giant insects).
_____________________Earth forms by cooling from a molten blob.
___________________ 1st continents form.
___________________ 1st photosynthesizing organisms
___________________ Pangaea breaks apart
___________________ Warm temperatures; No ice caps; Tropical forests
___________________ Ends with SNOWBALL EARTH
___________________ Series of closely spaced ice ages and mountain building
___________________ Giant trees and swamps become today’s coal.
___________________ Ozone develops from oxygen.
___________________ Reefs. Reefs. Reefs.
___________________ Mammals appear for the first time.