RELATIVE DATING ACTIVITY
DO NOT WRITE ON LAB PAPER – RECORD IN SCIENCE NOTEBOOK
Introduction. Stratigraphy is a relative dating technique that places organisms’ existence in sequential order
based on that order of strata in rock. You have received 9 rock samples from a paleontologist in California.
Your job is to arrange the samples in order from oldest to youngest according to their fossil content &
determine their relative ages using the process of relative dating. Absolute dating results won’t be available
from a laboratory for several weeks so your job is urgent. From previous knowledge you know that Sample 2 is
the oldest.
Purpose. This activity will demonstrate the process of using stratigraphy to compare the time periods in which
organisms lived.
Materials.
- strata cards
Fossil Key
Scientific
Name
Globus
slimius
Cicus
bozoensis
Fungus
amongius
Bogus
biggus
Microbius
hairiensis
Bananabana
bobana
Image
Procedures.
1. Arrange the fossil cards from oldest to youngest. Start with Sample 2 on the bottom because you know it
is the oldest. You may need to try several arrangements to get the cards in order. Remember that as an
organism becomes extinct, it no longer appears in younger rock samples. Verify your results are
correct before moving on.
2. Record the samples in order from bottom to top (oldest to youngest) in the first column of Table A.
Sample 2 has been done for you. It is not necessary to write the word Sample in each box.
3. Identify the fossils with the fossil key, and write their names in order by age from left to right in the first
row of the table.
4. Remember to examine your fossil cards carefully to determine where each fossil appears in the rock
record. Write an X in the appropriate column to indicate which fossil/fossils are present in each sample.
Check your progress with your teacher.
Scenario: You have received the actual dates from the absolute dating lab. The results became separated
from the samples. Since you know the order in which the samples are organized, you can match the
exact dates with their corresponding sample in the last column of the chart.
Fossil Ages
28.5 mya, 30.2 mya, 18.3 mya, 17.6 mya,
26.3 mya, 14.2 mya, 23.1 mya, 15.5 mya,
and 19.5 mya.
5. Determine the age ranges of all of your fossil species by measuring from the year the fossil first
appeared to the first year the fossil was absent from the rock record. Place this information in Table B.
Species
Year Present
Year Absent
Globus slimius
Microbius hairiensis
Fungus amongius
Cicus bozoensis
Bogus biggus
Bananabana bobana
6. Create a timeline that visually represents the periods of time in which each organism lived. Use a ruler
to measure out increments from 30 million years ago to 12 million years ago. Example:
30 mya
28 mya
26 mya
24 mya
22 mya
20 mya
18 mya
16 mya
14 mya
16 mya
14 mya
7. Place the ranges of each species from Table B on your timeline. Example:
Globus slimius
30 mya
28 mya
26 mya
24 mya
22 mya
20 mya
18 mya
Microbius hairiensis
Results.
Table A and Table B should be attached to your science notebook as well as the timeline.
Conclusion. Answer the following questions in paragraph form with complete sentences in preparation for a
class discussion:
1. Describe the stratigraphy and explain what information relative dating can provide to scientists.
2. Using the absolute dates, explain which species lived for the shortest period of time and which species
lived for the longest period of time.
Table A. Fossil Organisms in Sequential Order Based on Stratigraphy
Name of Fossil Organisms
Order of
Samples
Globus
slimius
Date
(mya)
Sample 2
X
Table B. Date Ranges for Fossil Organisms
Species
Year Present
Year Absent
Globus slimius
Microbius hairiensis
Fungus amongius
Cicus bozoensis
Bogus biggus
Bananabana bobana
Table A. Fossil Organisms in Sequential Order Based on Stratigraphy
Name of Fossil Organisms
Order of
Samples
Globus
slimius
Sample 2
X
Table B. Date Ranges for Fossil Organisms
Species
Year Present
Globus slimius
Microbius hairiensis
Fungus amongius
Cicus bozoensis
Bogus biggus
Bananabana bobana
Date
(mya)
Year Absent