25. Take a moment to look at the Biology Connection on page 226.Living near a volcano could be very dangerous. Why do so manypeople live close to volcanoes?

Review (p. 226)Now that youve finished Section 1, review what you learned byanswering the Review questions in your ScienceLog.

Section 2: Volcanoes Effects on Earth (p. 227)1. Volcanic eruptions have little effect on the Earth. True or False?

(Circle one.)

An Explosive Impact (p. 227)2. Figure 4 shows a cloud of volcanic ash flowing downhill. What

might happen when an ash flow mixes with water?

3. Ash fallout can cause floods by damming up

.

4. Place the following events in correct order to show how a singlevolcano can cause starvation and disease worldwide by writingthe appropriate number in the space provided.

Less sunlight reaches the Earth.

There is a large-scale volcanic eruption.

The Earth experiences longer, harsher winters and wetter,milder summers.

The average global temperature drops.

Worldwide food shortages occur because of widespreadcrop failures.

Volcanic ash and sulfur-rich gases spread around the globe.

Name _______________________________________________ Date ________________ Class______________

70 HOLT SCIENCE AND TECHNOLOGY

Chapter 9, continued

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Name _______________________________________________ Date ________________ Class______________

DIRECTED READING WORKSHEETS 71

Different Types of Volcanoes (p. 228)Match each volcano type in Column B with the correct descriptionin Column A, and write the appropriate letter in the correspondingspace. You may use the volcanoes in Column B more than once.

Craters and Calderas (p. 229)10. The crater of a volcano is located in the magma chamber.

True or False? (Circle one.)

11. When the roof over an empty magma chamber collapses, it

forms a . (crater or caldera)

Lava Plateaus (p. 229)12. Which of the following are characteristics of a lava plateau?

(Circle all that apply.)

a. It is made of runny lava that solidifies.b. It comes from a single volcano.c. It may cover thousands of square kilometers.d. It is the result of a nonexplosive eruption.

Review (p. 229)Now that youve finished Section 2, review what you learned byanswering the Review questions in your ScienceLog.

Section 3: What Causes Volcanoes? (p. 230)1. To help predict eruptions, scientists often rely on

based on rock samples.

Chapter 9, continuedC

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5. the largest mountain on Earth

6. forms from lava flows; not steep

7. often occurs in clusters

8. forms from alternating layers of pyroclastic material and lava

9. made entirely of pyroclastic materials

Column A Column B

a. shield volcano

b. cinder cone volcano

c. composite volcano

25. Take a moment to look at the Biology Connection on page 226.Living near a volcano could be very dangerous. Why do so manypeople live close to volcanoes?

Many people live close to volcanoes because soil enriched with volcanic

ash makes good farmland.

Review (p. 226)Now that youve finished Section 1, review what you learned byanswering the Review questions in your ScienceLog.

Section 2: Volcanoes Effects on Earth (p. 227)1. Volcanic eruptions have little effect on the Earth. True or False?

(Circle one.)

An Explosive Impact (p. 227)2. Figure 4 shows a cloud of volcanic ash flowing downhill. What

might happen when an ash flow mixes with water?

When an ash flow mixes with water, it takes on the consistency of wet

cement. The mixture might flow downhill, picking up debris as it goes. The

mudflow can cause immense damage because it is more powerful than an

ordinary river.

3. Ash fallout can cause floods by damming up

.

4. Place the following events in correct order to show how a singlevolcano can cause starvation and disease worldwide by writingthe appropriate number in the space provided.

3 Less sunlight reaches the Earth.1 There is a large-scale volcanic eruption.5 The Earth experiences longer, harsher winters and wetter,

milder summers.4 The average global temperature drops.6 Worldwide food shortages occur because of widespread

crop failures.2 Volcanic ash and sulfur-rich gases spread around the globe.

river valleys

Name _______________________________________________ Date ________________ Class______________

70 HOLT SCIENCE AND TECHNOLOGY

Chapter 9, continued

Cop

yrig

ht

by

Hol

t, R

ineh

art

and

Win

ston

. A

ll rig

hts

rese

rved

.

Name _______________________________________________ Date ________________ Class______________

DIRECTED READING WORKSHEETS 71

Different Types of Volcanoes (p. 228)Match each volcano type in Column B with the correct descriptionin Column A, and write the appropriate letter in the correspondingspace. You may use the volcanoes in Column B more than once.

Craters and Calderas (p. 229)10. The crater of a volcano is located in the magma chamber.

True or False? (Circle one.)

11. When the roof over an empty magma chamber collapses, it

forms a . (crater or caldera)

Lava Plateaus (p. 229)12. Which of the following are characteristics of a lava plateau?

(Circle all that apply.)

a. It is made of runny lava that solidifies.b. It comes from a single volcano.c. It may cover thousands of square kilometers.d. It is the result of a nonexplosive eruption.

Review (p. 229)Now that youve finished Section 2, review what you learned byanswering the Review questions in your ScienceLog.

Section 3: What Causes Volcanoes? (p. 230)1. To help predict eruptions, scientists often rely on

based on rock samples.models

caldera

Chapter 9, continuedC

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b

y H

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d W

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right

s re

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CH

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9

a 5. the largest mountain on Eartha 6. forms from lava flows; not steepb 7. often occurs in clustersc 8. forms from alternating layers of pyroclastic

material and lavab 9. made entirely of pyroclastic materials

Column A Column B

a. shield volcano

b. cinder cone volcano

c. composite volcano

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