Geologic Time Webquest
Biology 2008
Based on http://www.ucmp.berkeley.edu/education/explorations/tours/geotime/gtpage1.html
Answer these questions as your class progresses through this tutorial.
1. Approximately how old is the earth? 4.6 billion years old
2. When did the earliest life appear on earth? 3.9 billion years ago
3. What is missing when showing the relative order of events in a timeline? dates
4. What is the Law of Superposition? As more and more layers are deposited, the older rock layers end
up at the bottom of the sequence and the newer rock layers are toward the top
5. Draw a cross-section of a mountain with five basic rock layers and label the oldest and the youngest
layers. (not a mountain, but oh, well)
Youngest 
Oldest 
6. What process gives us absolute dates of rocks? Radiometric dating
7. What type of rock layer is easy to date? Volcanic ash
8. What does the Geologic Time Scale represent? The entire of history of earth since its formation 4.6
billion years ago
9. What is characteristic of the Pre-Archean? No life existed
10. What life form evolved during the Archean? bacteria
11. What does Proterozoic mean? Is this accurate? Explain. “before animal life,” not completely
accurate but life forms were very simple (algae, worms, etc.)
12. What three eras make up the Phanerozoic Eon? What does each name mean?
Paleozoic Era = “ancient life”; Mesozoic Era = “middle life”; Cenozoic Era = “recent life”