Name: ______________________________________________  Period:___________

Millimeters of Time


Introduction: The earth is estimated to be approximately 4.6 billion years old. Scientists have put together a geologic time scale, a calendar displaying the major events that have occurred since the earth was formed. This geologic time scale is based on the different types of organisms that have appeared during Earth’s history.


Task: Create a mathematical scale of geologic time that displays major evolutionary events.



·        Plot the events listed on the following page onto a time scale. Draw a line across the tape to mark the event.


·        The distance between the events on your scale must correspond with the amount of time between events. BE ACCURATE!!  I will grade your measurements. I would suggest starting with #17 and working your way back to #1 on the list of events.

§  Hint:  1 meter = 1 billion years

§  1 millimeter = 1 million years

§  How long will your time scale need to be? ________


·        The last million years are going to be tough to squeeze onto the scale because many important events have occurred and 1 mm is not a very big distance.

§  The best solution will be to enlarge this scale on a separate piece of paper. The last six events on the time scale will be included on this piece of paper. This part of the time scale does NOT have to be mathematically to scale.


·        Label every line. Labels should include the event and the year. For example, Formation of the Earth, 4.6 bya. Make sure it is clear which label goes with which line.


·        Please include a very colorful picture for each event. I will be grading neatness, creativity, if the time line is fully colored and if the pictures take up the entire time line.


·        Answer the questions when you are finished.





1.     How many years are represented by 1 mm? ________


2.     When did the first organism appear? What were the first organisms?



3.     Which appeared first on land, green plants or animals? ________________



4.     What were plants able to do that allowed them to survive without animals? _______________


5.     Which organisms have been on the earth for the shortest period of time? ________________


6.     Which lived on earth longer, dinosaurs or mammals? ______________________


7.     List three events in history that occurred in the last millimeter or time. (One per century.)

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8.     What do you think is the most important event on this time scale and why?




9.     Compare the complexity of the first organisms to appear on earth and the last.



10.            List the four eras of the geologic time scale.

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Events in the History of Earth


1.     Formation of Earth, 4.6 bya, beginning of the Precambrian era.

2.     First evidence of life (bacteria), 3.5 bya

3.     First known plants (algae) 3.2 bya

4.     First known animals (sponges or jellyfish), 1.2 bya

5.     Beginning of the Paleozoic Era (some invertebrate like worms, insects, starfish, mollusks or crabs/lobsters), 550 mya

6.     First backboned animals  (fish including sharks), 500 mya

7.     First land plants (moss or ferns), 440 mya

8.     First Amphibians (frogs or salamanders), 400 mya

9.     First Reptiles (snakes, lizards, or turtles) 305 mya

10.            End of Paleozoic Era, beginning of Mesozoic Era, first mammals (small rodents like mice), 245 mya

11. Age of Dinosaurs, 208 mya

12. First birds, 150 mya

13. Flowering plants, 140 mya

14. Dinosaurs become extinct, 66 mya

15. Mesozoic ends, Cenozoic begins, first primates (small monkeys like lemurs), 65 mya

          16. First elephants, 35 mya

          17. Human like animals appear, 2 mya

The last six events should be on a separate piece of paper:

18. Humans appear, 200,000 ya

19. Last ice age, 10,000 ya

20. Columbus discovers America, 1492

21. First U.S satellite, 1954

22. First man on the moon, 1969

23. Millennium celebration, 2000