Name: _________________
Guidelines for Note-taking: Chapter 13 Earth’s History
13.1 Precambrian History: Vast and Puzzling
1. When did the Precambrian Era begin? When did it end?
2. By looking at the time scale on P. 365, estimate the percentage of geologic time that the
Precambrian era encompasses.
3. Why is this era compared to a “long book with many missing pages”?
4. Briefly explain how Earth’s atmosphere evolved.
5. How did Earth’s oceans form?
6. What is the most common Precambrian fossil? Be sure to explain what these are.
13.2 Paleozoic Era: Life Explodes
1. Why is the Paleozoic divided into more detailed periods?
2. When did the Paleozoic begin? When did it end?
3. What is Gondwana Land?
4. Give some examples of early Paleozoic life.
5. What North American mountains formed during the late Paleozoic?
6. What is Laurasia?
7. What happened to Earth’s continents by the end of the Paleozoic?
8. Give some examples of late Paleozoic life. What was the dominant species during this
time?
9. What is the great Paleozoic extinction? What caused
it?
13.3 Mesozoic Era: Age of Reptiles
1. When did the Mesozoic begin? When did it end?
2. What was the dominant species during this time?
3. What happened to the continents during this time?
4. Today’s economy is largely based upon something
that began during this time period. What was it?
5. What North American mountains formed during this
time?
6. What happened at the end of the Mesozoic era? Why?
13.4 Cenozoic Era: Age of Mammals
1. When did the Cenozoic begin? When did it end?
2. Why do we know more about the Cenozoic than any
other era?
3. What is the dominant life form during this era?
4. Give some examples of the large mammals, now extinct, that lived during this era.
Study Guide: Geologic Time Scale
Use your text and notes to answer the following in your own words.
1. Which era in geologic time is the oldest? The longest? The youngest?
2. What is the geologic time scale and why is it useful to scientists?
3. Why do you think that only the Cenozoic Era is divided into epochs?
4. Compare the existence of humans with the existence of the dinosaurs. How long
has each species been on Earth?
5. Scientifically speaking, what is wrong with the cartoon below?
6. What would happen if scientists discovered a bird fossil that
dated back to the Permian Period?
7. Throughout Earth’s history, species have become extinct. What do you think
causes extinction? Specifically, what might have caused the mass extinction at
the end of the Paleozoic era?
8. We are in the midst of another mass extinction. Can you think of why this might
be happening now?
9. Describe how the Theory of Evolution and the geologic time scale are related.