Name: ________________________________________________________________________ Date: _________ Hour :_____
Fossils & Geologic Time
Study Guide
Directions: Answer the following questions in complete sentences on a separate sheet of paper.
1. Define the following terms in your own words:
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fossil
rock
geologic time scale
timeline
relative dating
erosion
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glacier
weathering
2. In what type of rock are fossils often found?
3. How do we use rock layers to determine geological history?
4. Describe how the principle of superposition is used in relative dating of rocks.
5. If a fossil is found in a rock layer, what do we know about the relative age of the fossil?
Use the diagram to the right to answer questions #6-8:
6. Which rock layer is oldest? How do you know?
7. Which rock layer is youngest? How do you know?
8. Which fossil is older: the one in rock layer C or rock layer B? Why?
Use the diagram to the right to answer question #9. You do not need to write in complete sentences for this part. Instead,
write the letter of the correct answer.
9.
a) Which rock layer is older: D or
B?
b) Which rock layer is older: B or E?
c) Which rock layer is younger: D
or F?
d) Which rock layer is younger: D or
C?
Use the timeline below to answer questions #10-#15.
BYA
10. How many billions of years ago did Earth form?
11. What happened approximately 2.6 bya?
12. Which occurred first: the rise in atmospheric oxygen or the moon formation?
13. Approximately how long ago did hard-shelled animals appear?
14. Which occurred first: the core formation or Jack Hills Zircon?
15. What event occurred most recently?
16. What 3 things do fossils provide ? (Hint: see your notes)
17. What is the fossil record?
18. How do geologists use the fossil record to determine
geological history?
Use the fossil record to the right to answer
questions #19-21:
19. During what period did reptile diversity occur?
20. What occurred during the Silurian period?
21. During what period did the first amphibians appear?
22. Give an example of erosion.
23. Describe the process of mountain building.
24. Explain what happens to mountains when they
go through erosion.
25. How are rocks used to measure geologic time?
26. What is a glacier?
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22. What occurred during the Jurassic period?
24. How can erosion expose rock layers?
26. Can mountain building change the shape of Earth’s surface?
30. How can glacier movement change the surface of Earth?
CONSTRUCTED RESPONSE:
How do geologists use fossils and rocks to determine Earth’s geologic history?
 Explain what a fossil is.
 Explain relative dating (discuss how rocks and fossils are both involved in relative dating).
 Explain how geologists use information gathered from fossils and relative dating to determine Earth’s geologic history.