- Landslides and mudslides
- Slump and creep
- Identify causes and effects of landslides and mudslides.
- Explain how slump and creep occur.
creep: extremely slow movement of rock and soil downhill because of gravity
landslide: rapid movement of soil, loose rock, and debris downhill under the influence of gravity
mass movement: any erosion in which soil, rock, debris, and/or mud move down a slope due to gravity
mudslide: movement of saturated, slippery soil downhill under the influence of gravity
slump: movement of a large block of rock and soil as a single unit down a slope due to gravity
Introducing the Lesson
Ask students to recall the agents of erosion and deposition they read about in previous lessons (running water, waves, wind, and glaciers). Tell them that gravity is another agent of erosion and deposition and they will read about it in this lesson.
Question: How do you think gravity causes erosion and deposition? How can gravity transport Earth materials and drop them somewhere else?
Answer: Gravity can move Earth materials by pulling them downhill.
Question: Where do you think erosion and deposition by gravity is most likely to occur?
Answer: Gravity is most likely to move materials on hills and mountains.
You may want to use the lesson plan at the following URL when you teach this lesson. If you use the lesson plan, students will learn about earthquake-induced landslides and the associated hazards, and how and why landslides occur. Students will also discuss steps they can take to reduce landslide hazards. The lesson plan includes a hands-on landslide activity in which students will observe the three phases of landslide development (slope failure, transport of materials, and final deposition of slide materials).
Have students makes a compare/contrast table for types of mass movement (landslides, mudslides, slump, and creep). They should compare the types in terms of how quickly they occur and how much destruction they cause.
Ask a small group of creative students to write a rap about mass movement. The rap should explain what causes mass movement and describe several different types of mass movement. Have the students teach their rap to the class.
Use the inquiry activity at the following URL when you teach students about landslides. In the activity, students will design a controlled experiment to test how different soil materials can produce different types of landslides. They will also explore how scientists predict where landslides may occur.
Share with students the following real-world impacts of landslides:
- Loss of human lives and damage to property
- Loss of tourist revenues and loss of industrial, agricultural, and forest productivity as a result of damage to land or facilities or interruption of transportation systems
- Reduced real estate values in areas threatened by landslides
- Loss of tax revenues from properties that are devalued because of landslides
- Cost of measures to prevent or lessen landslide damage
- Adverse effects on water quality in streams and irrigation facilities outside the landslide area
- Loss of human or animal productivity because of injury, death, or psychological trauma
- Secondary physical effects such as landslide-caused flooding
- Reduction in amount of stable land suitable for agriculture, homes, and businesses
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 10.5 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.
Points to Consider
Erosion and deposition are always changing Earth’s surface. Do you think that the same forces that cause erosion today—moving water, wind, ice, and gravity—were also at work in the past?
How might observations of erosion and deposition today help us understand Earth’s history?