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“Modeling the Geologic Time Scale Lab”
Note! In an effort to save paper, the observations section of this lab is
located at the end, behind the analysis and conclusion.
Introduction:
Applying the techniques of geologic dating, the history of Earth has been subdivided into several different units
that provide a meaningful time frame. These units, in order from largest to smallest, are Eons, Eras, Periods,
and Epochs. The events that make up Earth’s history can be arranged within this time frame to provide a
clearer picture of the past. The span of human life is like the blink of an eye compared to the age of Earth.
Because of this, it can be difficult to comprehend the magnitude of the geologic time scale.
Purpose:
We will create a scale representation of the geologic time scale in order to better understand the time spans
represented by each Eon, Era, Period, and Epoch.
Problem: How can the geologic time scale be represented in a way that allows a clearer visual
understanding?
Pre-Lab: (Refer to Figure 1. and write in complete sentences!)
1. How many different Eras make up the Phanerozoic Eon? ________________________
2. What is each named? __________________________________________________
__________________________________________________________________
3. What is the name of the longest Mesozoic Period? ____________________________
4. What is one major event that occurred between the Cretaceous and Tertiary Periods? __
__________________________________________________________________
5. During which Era and Period did humans develop? ______________________________
__________________________________________________________________
6. What are the names of the three Eons that together form “Precambrian” time? _______
__________________________________________________________________
7. About how many years ago did the first one-celled organisms form? ________________
__________________________________________________________________
Materials:
 Strip of adding machine paper measuring at 5 meters or longer
-or One large piece of butcher paper
 Meter stick or metric measuring tape
 Figure 1 (Geologic Time Scale)
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Procedure:
1. Obtain a piece of adding machine paper slightly longer than 5 meters in length. Draw a
line at one end of the paper and label it “Present.”
-or1. Obtain a large piece of butcher paper. Cut the butcher paper into strips that are at least
8 centimeters wide. Tape the strips together end-to-end until you have a blank timeline
at least 5 meters long. Draw a line at one end of the paper and label it “Present.”
2. Using the following scale, construct a timeline by completing steps 3 & 4.
Scale:
1 meter = 1 billion years
10 centimeters = 100 million years
1 centimeter = 10 million years
1 millimeter = 1 million years
3. Using the Geologic Time Scale as a reference, divide your timeline into the eons and eras
of geologic time. Label each division with its name and indicate its absolute age.
4. Using the scale, plot and label the 19 plant and animal events on your timeline that are
listed on the Geologic Time Scale.
Observations: (See next page).
Analysis and Conclusion
1. Calculating: What fraction or percent of geologic time is represented by the Precambrian
eon? _______________________________________________________________
__________________________________________________________________
2. Explaining: Using your text and class notes as references, explain why the approximate
time of 540 million years ago was selected to the mark the end of the Precambrian eon
and the beginning of Phanerozoic eon. ______________________________________
__________________________________________________________________
__________________________________________________________________
3. Inferring: Suggest one reason why the periods of the Cenozoic era have been further
subdivided into several epochs with reasonably reliable accuracy. __________________
__________________________________________________________________
__________________________________________________________________
4. Analyzing Data: How many times longer is the whole of geologic time than the time
represented by the 5000 years of recorded human history? _____________________
__________________________________________________________________
5. Calculating: For what fraction or percent of geologic time have land plants been present
on Earth? ___________________________________________________________
__________________________________________________________________
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Observations:
Figure 1. Geologic Time Scale
1. Use Figure 1 to create your timeline by following the above procedure.
2. Each group must turn-in one timeline at the end of the class period.