Name_______________________________ Date_________________

Constructing a Geologic Time Line

Purpose:

Materials: (per group)

Procedure:

1. Stretch out the adding-machine tape. Tape each end of the adding-machine tape onto the floor for a stable surface.

2. Using the meter stick, draw a straight vertical line down the middle of the adding-machine tape. The line that was drawn represents your time line.

3. Draw a horizontal line across one end of the adding-machine tape. Label this line "The present."

4. For your time line, use the following scale: 1mm= 1 million years, or 1m = 1 billion years.

5. Below you will be given a table with the periods of geologic time along with the number of years ago the period happened and a brief biologic record of each period.

6. Using the scale and the table, plot and label each period on the adding-machine tape.

   Start of Period, Million of Years before the Present	Period	Biologic Record
   2.5	Quaternary	Rise of humans; ice ages
   65	Tertiary	Flowering plants and grasses abundant; modern horse, camel, elephant develop; many new mammals appear
   136	Cretaceous	Dinosaurs die out; Flowering plants appear
   190	Jurassic	First birds appear; giant dinosaurs
   225	Triassic	First dinosaurs and mammals appear
   280	Permian	Rise of reptiles; large insects abundant
   325	Pennsylvanian	Large non flowering plants ex. ferns, conifers
   345	Mississippian	Large amphibians; extensive forests; sharks abundant
   395	Devonian	First forests and amphibians appear; fish abundant
   430	Silurian	First land animals (ex. spiders and scorpions); first land plants
   500	Ordovician	First vertebrates (fish)
   570	Cambrian	Marine shelled invertebrates
   1500	Late Precambrian	Marine invertebrates mainly without shells
   4500	Early Precambrian	Marine algae
   4600	Earth's Beginning?	Evolution of the Earth

Conclusion Questions:

1. Which time period is the longest?

2. Which time period is the shortest?

3. In which time periods did dinosaurs exist?

4. Did the mammals or the dinosaurs live on Earth for a longer amount of time? Explain your answer.

5. Why is there a question mark in the label "Earth's Beginning?"?

6. Did you find it difficult to plot any of the periods onto the time line? Explain.

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Contact Karen Krupinsky (kgurley@gsfc.nasa.gov) or Tammy Seergae (tseergae@umd.edu) for further information.