491
Companion Website
Key Terms
banded iron formations (p. 467)
cratons (p. 470)
eukaryotes (p. 477)
G I V E I T S O M E T H O U G H T
Refer to the geologic time scale in Figure 19.3. The Precambrian
accounts for nearly 90 percent of geologic time. Why do you think
it has fewer divisions than the rest of the time scale?
Referring to Figure 19.4, list the major events that led to the
formation of Earth.
What does the existence of iron-rich rocks during the Precambrian
indicate about the evolution of Earth’s atmosphere?
What are two ways that the appearance of a significant amount
of oxygen in the atmosphere relates to life?
Presently, about 71 percent of Earth’s surface is ocean covered.
This percentage was much higher early in Earth history. Explain.
Figure 19.12 shows the distribution of Earth’s ancient rocks. Explain
why there are so few rocks older than 3500 million years old on Earth.
6
5
4
3
2
1
Contrast the eastern and western margins of North America during
the Cenozoic era in terms of their relationships to plate boundaries.
Why do you think plants moved onto land before animals?
Refer to Figure 19.21. How has biodiversity changed with time?
How did mass extinctions contribute to this trend?
Some scientists have proposed that the environments around black
smokers may be similar to the extreme conditions that existed
early in Earth history. Therefore, they look to the unusual life that
exists around black smokers for clues about how earliest life may
have survived. Compare and contrast the environment of a black
smoker to the environment on Earth approximately 3 to 4 billion
years ago. Do you think there are parallels between the two, and if
so, do you think black smokers are good examples of the environment that earliest life may have experienced? Explain.
10
9
8
7
outgassing (p. 467)
planetesimals (p. 465)
prokaryotes (p. 477)
protoplanets (p. 465)
solar nebula (p. 465)
stromatolites (p. 477)
supercontinents (p. 471)
supercontinent cycle (p. 471)
supernova (p. 465)
suggest that early humans hastened their decline by selectively
hunting the larger animals. The Cenozoic could also be called
the “Age of Flowering Plants.” As a source of food, flowering
plants (angiosperms) strongly influenced the evolution of both
birds and herbivorous (plant-eating) mammals throughout
the Cenozoic era.
Companion Website
www.mygeoscienceplace.com
The Essentials of Geology, 11e companion Website contains numerous multimedia resources accompanied by assessments
to aid in your study of the topics in this chapter. The use of this site's learning tools will help improve your understanding
of geology. Utilizing the access code that accompanies this text, visit www.mygeoscienceplace.com in order to:
• Review key chapter concepts.
• Read with links to the Pearson eText and to chapter-specific web resources.
• Visualize and comprehend challenging topics using the learning activities in GEODe: Essentials of Geology and the
Geoscience Animations Library.
• Test yourself with online quizzes.
Companion Website
Key Terms
banded iron formations (p. 467)
cratons (p. 470)
eukaryotes (p. 477)
G I V E I T S O M E T H O U G H T
Refer to the geologic time scale in Figure 19.3. The Precambrian
accounts for nearly 90 percent of geologic time. Why do you think
it has fewer divisions than the rest of the time scale?
Referring to Figure 19.4, list the major events that led to the
formation of Earth.
What does the existence of iron-rich rocks during the Precambrian
indicate about the evolution of Earth’s atmosphere?
What are two ways that the appearance of a significant amount
of oxygen in the atmosphere relates to life?
Presently, about 71 percent of Earth’s surface is ocean covered.
This percentage was much higher early in Earth history. Explain.
Figure 19.12 shows the distribution of Earth’s ancient rocks. Explain
why there are so few rocks older than 3500 million years old on Earth.
6
5
4
3
2
1
Contrast the eastern and western margins of North America during
the Cenozoic era in terms of their relationships to plate boundaries.
Why do you think plants moved onto land before animals?
Refer to Figure 19.21. How has biodiversity changed with time?
How did mass extinctions contribute to this trend?
Some scientists have proposed that the environments around black
smokers may be similar to the extreme conditions that existed
early in Earth history. Therefore, they look to the unusual life that
exists around black smokers for clues about how earliest life may
have survived. Compare and contrast the environment of a black
smoker to the environment on Earth approximately 3 to 4 billion
years ago. Do you think there are parallels between the two, and if
so, do you think black smokers are good examples of the environment that earliest life may have experienced? Explain.
10
9
8
7
outgassing (p. 467)
planetesimals (p. 465)
prokaryotes (p. 477)
protoplanets (p. 465)
solar nebula (p. 465)
stromatolites (p. 477)
supercontinents (p. 471)
supercontinent cycle (p. 471)
supernova (p. 465)
suggest that early humans hastened their decline by selectively
hunting the larger animals. The Cenozoic could also be called
the “Age of Flowering Plants.” As a source of food, flowering
plants (angiosperms) strongly influenced the evolution of both
birds and herbivorous (plant-eating) mammals throughout
the Cenozoic era.
Companion Website
www.mygeoscienceplace.com
The Essentials of Geology, 11e companion Website contains numerous multimedia resources accompanied by assessments
to aid in your study of the topics in this chapter. The use of this site's learning tools will help improve your understanding
of geology. Utilizing the access code that accompanies this text, visit www.mygeoscienceplace.com in order to:
• Review key chapter concepts.
• Read with links to the Pearson eText and to chapter-specific web resources.
• Visualize and comprehend challenging topics using the learning activities in GEODe: Essentials of Geology and the
Geoscience Animations Library.
• Test yourself with online quizzes.