- How glaciers form
- Erosion by glaciers
- Deposition by glaciers
- Describe how continental and valley glaciers form.
- Explain how glaciers cause erosion.
- Identify landforms deposited by glaciers.
continental glacier: mass of flowing ice that covers a large area and is not confined to a valley
glacial till: mixture of particles and rocks of different sizes deposited by a glacier
glacier: large mass of flowing ice
moraine: any linear deposit of unsorted sediments that have been dropped by a glacier
plucking: process in which a glacier picks up sediments as it flows over the ground and the sediments freeze to the bottom of the glacier
valley glacier: mass of ice that flows downhill through a mountain valley
Introducing the Lesson
Introduce glaciers by showing students impressive images of glaciers (see URL below). Ask students to describe what they are observing, and challenge them to explain how glaciers form. Accept all reasonable responses. Then tell students they will learn how glaciers form when they read this lesson.
Use the demonstration “Glacier in a Milk Jug” (no. 58 in the document below) to show your class how a glacier deposits landforms as it recedes. Students will observe how the surface may be altered by a glacier as it melts. Students can also predict how deposition and runoff might affect vegetation and the numbers of species in an area.
Building Science Skills
Students can model a glacier and observe how it moves and interacts with objects with the simple activity “Watch a Glacier Model on the Move,” which is described at the following URL.
Pair any struggling students with students who are doing well in the class. Then ask partners to create a Venn diagram showing similarities and differences between continental and valley glaciers.
If students want to learn more about glaciers, direct them to the National Snow and Ice Data Center's Web site (see below). The site includes publications, data, images, quick facts, and much more.
In the inquiry activity at the URL below, students can simulate ways that landforms are affected by glaciation. In addition to the activity materials and procedure, the URL provides discussion questions, evaluation, extensions, and vocabulary.
Students commonly think that glaciers erode by pushing rocks like a bulldozer. Explain how pressure, melting, and freezing cause glaciers to erode. For example, when a glacier encounters a boulder, the boulder presses against the ice. The increase in pressure causes the ice to melt around the boulder. When the water refreezes, it encases the boulder in ice. This allows the glacier to pick up the boulder and carry it off.
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 10.4 Quiz in CK-12 Earth Science for Middle School Quizzes and Tests.
Points to Consider
So far in this chapter, you’ve read how moving water, air, and ice shape Earth’s surface. Water and ice move because of gravity. Do you think gravity can erode and deposit sediment without the help of water or ice?
How might gravity alone shape Earth’s surface?