Names ___________________________________________ Period: ________
Geologic Timeline Lab
The Earth has changed dramatically and repeatedly over a history that spans around 4.6 billion years. Such
immense spans of time are difficult for most of us to comprehend. They fall outside our range of human
experience. We normally deal with much shorter time intervals, like the when we have to be at work or what
time a movie is playing, or even the number of days until graduation!
Extremely slow geologic processes have little meaning. To appreciate the magnitude of geologic time and the
history of our incredible planet, you will be creating a timeline of important geologic events scaled to a size
more tangible and familiar. Our timeline will be 4.6 meters long to represent the 4.6 billions years of earth.
All of the times that we are going to deal with in this lab are in millions of years ago (mya). To figure out the
lengths that we need in this lab use the following proportion as well as what we discuss in our pre-lab:
Distance (cm)
460 cm
Age of event (mya)
4600 million years
Procedure
1.
2.
3.
4.
You will need 4.6 meters of paper. Use the measurement on the back table.
Tape it to the ground so it is all the way open
Label on one end FORMATION OF THE EARTH and the other end PRESENT
All of our times are in million of years ago so we will make ALL OF OUR MEASUREMENTS FROM THE
END THAT SAYS PRESENT. Draw one long straight line down the center of your tape and place a
mark at each meter from the PRESENT.
5. Our first step will be to place the 4 eras on the timeline using the proportion above to label them in
the correct spot on the timeline.
6. Label the START of each era only since the next era begins where the previous one ended.
7. Shade each line section a different color so you can see four distinct eras.
Name of the Era
Age of Era
Precambrian
4600 mya-544 mya
Paleozoic
544 mya-251 mya
Mesozoic
251 mya-65 mya
Cenozoic
65 mya-0 mya
Length on Timeline
Color
8. Using the same proportion, you need to determine the distance from the PRESENT end of the
timeline for each of the important events listed on the next page.
9. Place the events on the timeline in the correct locations and label them with a straight line. Be as
neat as possible with your distances and labeling
10. Have your teacher check off your timeline when you are completely done.
Name of the Event
Age of Event
Oldest mineral grain found
4400 mya
Oldest piece of rock ever found
4000 mya
First evidence of life
3800 mya
First fossils-algae and bacteria
3500 mya
Free oxygen found in atmosphere
1800 mya
Cambrian Explosion (first
appearance of abundant fossils)
Formation of Pangea
540 mya
Largest mass extinction (volcanic
activity – magma plume)
Abundant dinosaurs
250 mya
Dinosaur Extinction (meteorite
impact)
Earliest humans
65 mya
Beginning of Last Ice Age
1 mya
First homo sapiens
0.004 mya
Distance from PRESENT in centimeters
290 mya
150 mya
6 mya
Answer the following Questions:
1. What percent of the timeline falls in the Precambrian era?
2. What percent of the Earth’s history has man been in existence?
3. What percent of the Earth’s history has there been abundant fossils?
4. The universe is about 15 billion years old (15000 million) what percentage of THAT time has the Earth
been in existence?
5. Evaluate the statement “The reason why there is so much time in between early events in Earths history
is that there was very little going on” Do you believe this statement is true or false? Why?
6. How do scientists determine when an era begins and when it ends?
7. What types of information did geologists use to develop the geologic time scale?
8. Using radioactive dating, geologists determine that a layer of igneous rock from a lava flow is 60 million
years old. What can you conclude about the age of a layer of sedimentary rock that lies just below the
igneous rock? Explain.
9. How long will it take for the amount of potassium-40, which has a half-life of 1.3 billion years, in a rock
to decay from 60 milligrams to 15 milligrams? (Hint: First, you need to figure out how many half lives it
took to get from 60 mg to 15 mg)