Name: ___________________________________
TOC#____
Read pages 484-499, 541-544 in your Science Textbook and answer the following questions.
1. What is the difference between relative and absolute dating?
2. How would a geologist use the principle of superpostition to determine the relative ages of the rocks in the Grand
Canyon?
3. What is significant about materials that contain C-14?
4. A scientist finds the charred remains of a tree in a layer of volcanic ash thought to be from the eruption of Mt.
Mazama some 6600 years ago. Which radioactive isotope, U-238 or C-14, would you use to verify the actual age of
the charred wood? Explain your answer.
5. What is a fossil?
6. What is the difference between a fossil with original preservation and an altered hard part?
7. What are the characteristics of an index fossil?
8. How might a mold or cast of a fossil help scientists to interpret the type of environment the organism lived in?
 Relative Dating Techniques
1. In an undisturbed rock sequence, the youngest rock layer is located
.
2. The geologic principle that states that sedimentary rocks are deposited in horizontal layers is the principle of
.
3. You can tell that a fault is younger than the rock it cuts across by applying the principle of
.
Use the diagram below to answer the next 6 questions.
4. Which fossil is probably older, A or C?
5. Which fossil is probably the most recent, B or C?
6. What facts about fossils did you use to answer questions 4 and 5?
7. Which fossil is probably the most complex, A, B, C, or D?
8. Which fossil is probably the most simple, A, B, C, or D?
9. Explain your answer to number 7 and 8.
 Absolute Dating Techniques
Use the table below to answer the next 6 questions.
Time 1=0 years
=0 half-lives
Time 2=5730 years
=1 half-lives
Time 3=11560 years
=2 half-lives
Time 4=17090 years
=3 half-lives
100% C-14
0% N-14
50% C-14
50% N-14
25% C-14
75% N-14
12.5% C-14
87.5% N-14
10. Which element is the radioactive isotope?
11. Which element shown is the stable non-radioactive element?
12. What is the half-life of C-14?
13. How many half-lives will it take for all but 25 percent of the original C-14 to decay?
How many years?
14. What percentage of C-14 remains after three half-lives?
15. What percentage of N-14 forms after 17,090 years?
CHALLENGE QUESTIONS: show me what you are made of 
Refer to pages 485-495 to answer the following question:
1. How are the law of superposition and the principle of fossil succession related?
Refer to pages 496-499 to answer the following question:
1. Explain how radioactivity and radiometric dating are related.
2