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CHAPTER
8
VOCABULARY & NOTES WORKSHEET
Volcanoes
By studying the Vocabulary and Notes listed for each section below, you can gain a
better understanding of this chapter.
SECTION 1
Vocabulary
In your own words, write a definition of each of the following terms in the space provided.
1. magma
CHAPTER 8
2. vent
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▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
3. lava
4. pyroclastic material
5. volcano
Notes
Read the following section highlights. Then, in your own words, write the highlights in
your ScienceLog.
• Volcanoes erupt both explosively and nonexplosively.
• The characteristics of a volcanic eruption are largely determined by the type of magma
within the volcano.
STUDY GUIDE
67
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Volcanoes, continued
• The amount of silica in magma determines whether it is thin and fluid or thick and
stiff.
• Lava hardens into characteristic features that range from smooth to jagged, depending
on how thick the lava is and how quickly it flows.
• Pyroclastic material, or volcanic debris, consists of solid pieces of the volcano as well as
magma that solidifies as it travels through the air.
SECTION 2
Vocabulary
In your own words, write a definition of each of the following terms in the space provided.
1. shield volcano
3. composite volcano
4. crater
5. caldera
68
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Copyright © by Holt, Rinehart and Winston. All rights reserved.
2. cinder cone volcano
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Volcanoes, continued
Notes
Read the following section highlights. Then, in your own words, write the highlights in
your ScienceLog.
• The effects of volcanic eruptions are felt both locally and around the world.
• Volcanic mountains can be classified according to their composition and overall shape.
• Craters are funnel-shaped pits that form around the central vent of a volcano. Calderas
are large bowl-shaped depressions formed by a collapsed magma chamber.
• In the largest type of volcanic eruption, lava simply pours from long fissures in the
Earth’s crust to form lava plateaus.
SECTION 3
Vocabulary
In your own words, write a definition of each of the following terms in the space provided.
CHAPTER 8
1. rift
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▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
2. hot spot
Notes
Read the following section highlights. Then, in your own words, write the highlights in
your ScienceLog.
• Volcanoes result from magma formed in the mantle.
• When pressure is reduced, some of the solid rock of the already hot mantle melts to
form magma.
• Because it is less dense than the surrounding rock, magma rises to the Earth’s surface.
It either erupts as lava or solidifies in the crust.
• Most volcanic activity takes place along tectonic plate boundaries, where plates either
separate or collide.
• Volcanoes also occur above hot spots in the mantle. As a tectonic plate moves over the
hot spot, a chain of volcanic islands forms.
• Volcanic eruptions cannot be predicted with complete accuracy. But scientists now have
several methods of forecasting future eruptions.
STUDY GUIDE
69
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Name _______________________________________________ Date ________________ Class______________
CHAPTER
8
CHAPTER REVIEW WORKSHEET
Volcanoes
USING VOCABULARY
For each pair of terms, explain the difference in their meanings.
1. caldera/crater
2. lava/magma
4. vent/rift
5. cinder cone volcano/shield volcano
70
HOLT SCIENCE AND TECHNOLOGY
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3. lava/pyroclastic material
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Volcanoes, continued
UNDERSTANDING CONCEPTS
Multiple Choice
6. The type of magma that often produces a violent eruption can be described as
a. thin due to high silica content.
b. thick due to high silica content.
c. thin due to low silica content.
d. thick due to low silica content.
7. When lava hardens quickly to form ropy formations, it is called
a. aa lava.
b. pahoehoe lava.
c. pillow lava.
d. blocky lava.
CHAPTER 8
8. Volcanic dust and ash can remain in the atmosphere for months or years, causing
a. decreased solar reflection and higher temperatures.
b. increased solar reflection and lower temperatures.
c. decreased solar reflection and lower temperatures.
d. increased solar reflection and higher temperatures.
▼
▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
9. Mount St. Helens, in Washington, covered the city of Spokane with tons of ash.
Its eruption would most likely be described as
a. nonexplosive, producing lava.
b. explosive, producing lava.
c. nonexplosive, producing pyroclastic material.
d. explosive, producing pyroclastic material.
10. Magma forms within the mantle most often as a result of
a. high temperature and high pressure.
b. high temperature and low pressure.
c. low temperature and high pressure.
d. low temperature and low pressure.
11. At
a.
b.
c.
d.
divergent plate boundaries,
heat from the Earth’s core produces mantle plumes.
plates are subducted, causing magma to form.
tectonic plates move apart.
hot spots produce volcanoes.
12. A theory that helps to explain the causes of both earthquakes and volcanoes is the
theory of
a. subduction.
b. plate tectonics.
c. climatic fluctuation.
d. mantle plumes.
STUDY GUIDE
71
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Volcanoes, continued
Short Answer
13. Briefly describe two methods that scientists use to predict volcanic eruptions.
15. Along what types of tectonic plate boundaries are volcanoes generally found? Why?
72
HOLT SCIENCE AND TECHNOLOGY
Copyright © by Holt, Rinehart and Winston. All rights reserved.
14. Describe how differences in magma affect volcanic eruptions.
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Volcanoes, continued
16. Describe the characteristics of the three types of volcanic mountains.
CONCEPT MAPPING
CHAPTER 8
17. Use any of the terms from the vocabulary lists in Chapter Highlights to construct a
concept map that illustrates the relationship between types of magma, the eruptions
they produce, and the shapes of the volcanoes that result.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
▼
▼
▼
STUDY GUIDE
73
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
CRITICAL THINKING AND PROBLEM SOLVING
Write one or two sentences to answer the following questions:
18. Imagine that you are exploring a volcano that has been dormant for some time. You
begin to keep notes on the types of volcanic debris you encounter as you walk. Your
first notes describe volcanic ash, and later your notes describe lapilli. In what direction would you most likely be traveling—toward or away from the crater? Explain.
20. What do you think would happen to the Earth’s climate if volcanic activity increased
to 10 times its current level?
MATH IN SCIENCE
21. Midway Island is 1,935 km northwest of Hawaii. If the Pacific plate is moving to the
northwest at 9 cm per year, how long ago was Midway Island located over the hot
spot that formed it?
74
HOLT SCIENCE AND TECHNOLOGY
Copyright © by Holt, Rinehart and Winston. All rights reserved.
19. Loihi is a future Hawaiian island in the process of forming on the ocean floor.
Considering how this island chain formed, tell where you think the new volcanic
island will be located and why.
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
INTERPRETING GRAPHICS
The following graph illustrates the average change in temperature above or below normal
for a community over several years. Use the graph to answer the questions that follow.
0.2
0
–0.2
–0.4
–0.6
1991
1992
1993
1994
CHAPTER 8
Temperature change from normal (˚C)
Average Temperature Variation
Year
▼
▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
22. If the variation in temperature over the years was influenced by a major volcanic
eruption, when did the eruption most likely take place? Explain.
23. If the temperature were plotted only in yearly intervals rather than several times per
year, how might your interpretation be different?
NOW WHAT DO YOU THINK?
Take a minute to review your answers to the ScienceLog questions at the beginning of this
chapter. Have your answers changed? If necessary, revise your answers based on what you
have learned since you began this chapter.
STUDY GUIDE
75
Menu
Print
Name _______________________________________________ Date ________________ Class______________
CHAPTER
8
VOCABULARY & NOTES WORKSHEET
Volcanoes
By studying the Vocabulary and Notes listed for each section below, you can gain a
better understanding of this chapter.
SECTION 1
Vocabulary
In your own words, write a definition of each of the following terms in the space provided.
1. magma the hot liquid that forms when rock partially or completely melts; may include mineral
crystals
CHAPTER 8
2. vent a hole or crack in the Earth’s crust through which magma rises to the surface
Copyright © by Holt, Rinehart and Winston. All rights reserved.
4. pyroclastic material magma and fragments of rock that are ejected into the atmosphere during
a violent volcanic eruption
5. volcano a mountain that forms when lava or pyroclastic material builds up around a volcanic vent
Notes
Read the following section highlights. Then, in your own words, write the highlights in
your ScienceLog.
• Volcanoes erupt both explosively and nonexplosively.
• The characteristics of a volcanic eruption are largely determined by the type of magma
within the volcano.
STUDY GUIDE
67
▼
▼
▼
3. lava magma that erupts onto the Earth’s surface
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Volcanoes, continued
• The amount of silica in magma determines whether it is thin and fluid or thick and
stiff.
• Lava hardens into characteristic features that range from smooth to jagged, depending
on how thick the lava is and how quickly it flows.
• Pyroclastic material, or volcanic debris, consists of solid pieces of the volcano as well as
magma that solidifies as it travels through the air.
SECTION 2
Vocabulary
In your own words, write a definition of each of the following terms in the space provided.
1. shield volcano a large gently sloped volcano that forms from repeated, nonexplosive eruptions
of lava
2. cinder cone volcano a small, steeply sloped volcano that forms from moderately explosive
3. composite volcano a volcano made of alternating layers of lava and pyroclastic material; also
called stratovolcano
4. crater a funnel-shaped pit around the central vent of a volcano
5. caldera a circular depression that forms when a magma chamber empties and causes the ground
above to sink
68
HOLT SCIENCE AND TECHNOLOGY
Copyright © by Holt, Rinehart and Winston. All rights reserved.
eruptions of pyroclastic material
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
Notes
Read the following section highlights. Then, in your own words, write the highlights in
your ScienceLog.
• The effects of volcanic eruptions are felt both locally and around the world.
• Volcanic mountains can be classified according to their composition and overall shape.
• Craters are funnel-shaped pits that form around the central vent of a volcano. Calderas
are large bowl-shaped depressions formed by a collapsed magma chamber.
• In the largest type of volcanic eruption, lava simply pours from long fissures in the
Earth’s crust to form lava plateaus.
SECTION 3
Vocabulary
In your own words, write a definition of each of the following terms in the space provided.
2. hot spot a place within a tectonic plate that sits directly above a rising column of magma called a
▼
▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
mantle plume
CHAPTER 8
1. rift a zone of thin, fractured lithosphere that forms between tectonic plates as they separate
Notes
Read the following section highlights. Then, in your own words, write the highlights in
your ScienceLog.
• Volcanoes result from magma formed in the mantle.
• When pressure is reduced, some of the solid rock of the already hot mantle melts to
form magma.
• Because it is less dense than the surrounding rock, magma rises to the Earth’s surface.
It either erupts as lava or solidifies in the crust.
• Most volcanic activity takes place along tectonic plate boundaries, where plates either
separate or collide.
• Volcanoes also occur above hot spots in the mantle. As a tectonic plate moves over the
hot spot, a chain of volcanic islands forms.
• Volcanic eruptions cannot be predicted with complete accuracy. But scientists now have
several methods of forecasting future eruptions.
STUDY GUIDE
69
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Name _______________________________________________ Date ________________ Class______________
CHAPTER
8
CHAPTER REVIEW WORKSHEET
Volcanoes
USING VOCABULARY
For each pair of terms, explain the difference in their meanings.
1. caldera/crater A caldera forms when the roof of a magma chamber collapses. A crater forms
when the material above the main vent of a volcano is blasted out.
2. lava/magma Magma is hot, liquid material. Lava is magma that flows out onto the Earth’s surface.
3. lava/pyroclastic material Lava is mostly liquid and is thin and runny. Lava flows out a volcanic
vent onto the ground. Pyroclastic material is mostly solid rock and is blasted into the air in a vio-
4. vent/rift A vent is a hole in the Earth’s surface that allows lava or pyroclastic material to erupt.
A rift is a long, deep crack in the Earth’s surface that forms when tectonic plates separate.
5. cinder cone volcano/shield volcano A shield volcano forms when lava erupts and spreads
out over large areas. A cinder cone volcano forms when pyroclastic material erupts and piles up
around the volcanic vent.
70
HOLT SCIENCE AND TECHNOLOGY
Copyright © by Holt, Rinehart and Winston. All rights reserved.
lent volcanic eruption.
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
UNDERSTANDING CONCEPTS
Multiple Choice
6. The type of magma that often produces a violent eruption can be described as
a. thin due to high silica content.
b. thick due to high silica content.
c. thin due to low silica content.
d. thick due to low silica content.
7. When lava hardens quickly to form ropy formations, it is called
a. aa lava.
b. pahoehoe lava.
c. pillow lava.
d. blocky lava.
CHAPTER 8
8. Volcanic dust and ash can remain in the atmosphere for months or years, causing
a. decreased solar reflection and higher temperatures.
b. increased solar reflection and lower temperatures.
c. decreased solar reflection and lower temperatures.
d. increased solar reflection and higher temperatures.
▼
▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
9. Mount St. Helens, in Washington, covered the city of Spokane with tons of ash.
Its eruption would most likely be described as
a. nonexplosive, producing lava.
b. explosive, producing lava.
c. nonexplosive, producing pyroclastic material.
d. explosive, producing pyroclastic material.
10. Magma forms within the mantle most often as a result of
a. high temperature and high pressure.
b. high temperature and low pressure.
c. low temperature and high pressure.
d. low temperature and low pressure.
11. At
a.
b.
c.
d.
divergent plate boundaries,
heat from the Earth’s core produces mantle plumes.
plates are subducted, causing magma to form.
tectonic plates move apart.
hot spots produce volcanoes.
12. A theory that helps to explain the causes of both earthquakes and volcanoes is the
theory of
a. subduction.
b. plate tectonics.
c. climatic fluctuation.
d. mantle plumes.
STUDY GUIDE
71
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
Short Answer
13. Briefly describe two methods that scientists use to predict volcanic eruptions.
Answers will vary but should include two of the following: measuring changes in the frequency of
small earthquakes near the volcano; measuring changes in the slope of the volcano; measuring
changes in the ratios of different volcanic gases over time; and measuring changes in how much
heat escapes a volcano by using infrared satellite images.
14. Describe how differences in magma affect volcanic eruptions.
Magma that has a high water and silica content will more likely produce a violent volcanic eruption
than magma that has a low water and silica content. Water turns to steam, which builds up a great
amount of pressure, which leads to explosive eruptions. Silica makes magma thick, allowing it to
15. Along what types of tectonic plate boundaries are volcanoes generally found? Why?
Volcanoes are generally found along convergent boundaries because in a subduction zone, oceanic
crust is forced downward, which adds water to the mantle. The addition of water lowers the mantle rock’s melting point. This melted mantle becomes magma that rises to the surface to form
volcanoes.
72
HOLT SCIENCE AND TECHNOLOGY
Copyright © by Holt, Rinehart and Winston. All rights reserved.
trap volcanic gases such as water (steam).
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Volcanoes, continued
16. Describe the characteristics of the three types of volcanic mountains.
Cinder cones are made from a pyroclastic eruption, are small, and have steep sides. Shield volcanoes are made of lava that runs over great distances before it solidifies, making very large, gently
sloped volcanoes. Composite volcanoes are made of both lava and pyroclastic material. Composite
volcanoes have large, gently sloping bases and steep sides.
CONCEPT MAPPING
CHAPTER 8
17. Use any of the terms from the vocabulary lists in Chapter Highlights to construct a
concept map that illustrates the relationship between types of magma, the eruptions
they produce, and the shapes of the volcanoes that result.
▼
▼
▼
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Volcanoes
are classified as
shield
volcanoes
composite
volcanoes
cinder cone
volcanoes
which are
made from
which are
made from
which are
made from
lava
pyroclastic
material
STUDY GUIDE
73
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
CRITICAL THINKING AND PROBLEM SOLVING
Write one or two sentences to answer the following questions:
18. Imagine that you are exploring a volcano that has been dormant for some time. You
begin to keep notes on the types of volcanic debris you encounter as you walk. Your
first notes describe volcanic ash, and later your notes describe lapilli. In what direction would you most likely be traveling—toward or away from the crater? Explain.
You would be traveling toward the volcano because the larger the pyroclastic material is, the closer
it will be to the vent. It takes more energy to move larger rocks than it does to move smaller rocks.
19. Loihi is a future Hawaiian island in the process of forming on the ocean floor.
Considering how this island chain formed, tell where you think the new volcanic
island will be located and why.
The new island will be located southeast of Hawaii because the hot spot stays in the same place,
20. What do you think would happen to the Earth’s climate if volcanic activity increased
to 10 times its current level?
The overall surface temperature of the Earth would decrease because all the volcanic ash in the
atmosphere would block out much of the sun’s energy.
MATH IN SCIENCE
21. Midway Island is 1,935 km northwest of Hawaii. If the Pacific plate is moving to the
northwest at 9 cm per year, how long ago was Midway Island located over the hot
spot that formed it?
1 km 1,000 m 100,000 cm
1,935 km 193,500,000 cm
193,500,000/9 cm per year 21,500,000 years
74
HOLT SCIENCE AND TECHNOLOGY
Copyright © by Holt, Rinehart and Winston. All rights reserved.
while the Pacific plate moves above it toward the northwest.
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Name _______________________________________________ Date ________________ Class______________
Volcanoes, continued
INTERPRETING GRAPHICS
The following graph illustrates the average change in temperature above or below normal
for a community over several years. Use the graph to answer the questions that follow.
0.2
0
–0.2
–0.4
–0.6
1992
1993
1994
Year
22. If the variation in temperature over the years was influenced by a major volcanic
eruption, when did the eruption most likely take place? Explain.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
The eruption probably happened in 1992 because that year had the lowest temperature below normal. The volcanic ash that is erupted into the atmosphere blocks the sunlight, lowering temperature.
23. If the temperature were plotted only in yearly intervals rather than several times per
year, how might your interpretation be different?
If the temperature were plotted in only yearly intervals, it would look as if 1993 or 1994 had the
lowest temperatures. This would mean that the eruptions happened in 1993 or 1994 instead of
1992.
NOW WHAT DO YOU THINK?
Take a minute to review your answers to the ScienceLog questions at the beginning of this
chapter. Have your answers changed? If necessary, revise your answers based on what you
have learned since you began this chapter.
STUDY GUIDE
75
CHAPTER 8
1991
▼
▼
▼
Temperature change from normal (˚C)
Average Temperature Variation