- Composite volcanoes, shield volcanoes, and cinder cones
- Describe the basic shapes of volcanoes.
- Compare the features of volcanoes.
- Describe the stages in the formation of volcanoes.
caldera: large, circular hole formed when the top of a volcano collapses after an eruption empties the magma chamber
cinder cone: small volcano composed of rock fragments piled on top of one another
composite volcano: tall, cone-shaped volcano with steeply sloping sides that is composed of alternating layers of ash and lava
shield volcano: broad-based, shield-shaped volcano with gently sloping sides that is composed almost entirely of lava
strata: layers of sediments or of lava and ash deposited by a volcano
supervolcano: massive volcano that can produce rare but enormous eruptions
Introducing the Lesson
Ask students to recall the two types of volcanic eruptions they read about in the previous lesson, “Volcanic Eruptions.” (The two types are explosive and non-explosive eruptions.) Then ask them to predict how volcanoes might differ if they erupt in these two different ways. Accept all reasonable responses at this point, and tell students they will learn in this lesson how the type of eruption affects the type of volcano that forms.
Building Science Skills
Do the activity at the following URL as a group activity. Each group will research a different volcano and present information about it to the class. Then the rest of the students will try to identify the type of volcano based on the information provided.
Set up a gallery walk for types of volcanoes. Attach four pieces of poster board to different walls of the classroom, and label them “Composite Volcano,” “Shield Volcano,” “Cinder Cone,” and “Supervolcano.” Divide the class into groups that incorporate any differential learners with other students. Ask groups to move around the room from poster to poster and list what they know about each type of volcano. Afterward, review the posters with the class and correct any errors.
Tell students that Jupiter’s moon Io is the most volcanically active body in the solar system. Have them investigate Io’s volcanic activity, starting with the URLs below. The students should find out why Io is so active volcanically and how volcanic activity has affected its surface. Ask students to share what they learn in a brief oral report to the class. Discuss as a class how the cause of Io’s volcanic activity differs from that of Earth.
At the URL below, you can find an activity in which students make a three-dimensional paper model of a volcano. The model will help students visualize a composite volcano (inside and out) and understand how it forms. Students will also gain an understanding of how the volcano’s shape is related to its internal structure. Included at the URL are the paper model, instructions for assembly, a teachers' guide, and a simple description of volcanoes.
Discuss the following common volcano misconceptions with the class. Call on students to explain why each statement is false. Help them find examples of specific volcanoes that show the misconceptions do not apply. You can learn more at the following URL.
- All volcanoes erupt violently.
- Volcanoes only erupt straight up through the top vent.
- If a volcano doesn’t erupt for a hundred years, it must be extinct.
- If a volcano does not produce lava, it is not dangerous.
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Earth Science for Middle School Workbook. Ask students to complete the worksheets alone or in pairs to reinforce lesson content.
Lesson Review Questions
Have students answer the Review Questions listed at the end of the lesson in the FlexBook® student edition.
Check students’ mastery of the lesson with Lesson 8.3 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.
Points to Consider
Composite volcanoes usually have craters on the top. Why are the craters sometimes U- or horseshoe-shaped?
A shield volcano is relatively flat and a composite volcano is relatively steep because of the type of magma that creates them. What type of lava might create a volcano that is steeper than a shield volcano but not as steep as a composite volcano?
Some people believe there would be a worldwide catastrophe if a huge asteroid hits the Earth. How might an asteroid impact and a supervolcano eruption be similar?