Lesson Plan

Formation of Mountains and Faults

A mountain with snow
Grade Level:
Middle School: Sixth Grade through Eighth Grade
Lesson Duration:
60 Minutes

Essential Question

How do mountains form?


Students will be able to:
• Simulate with simple models geologic mountain building processes.
• Define geologic terms.
• Recognize the effects that weathering/erosion have on the mountains.
• Consider compatibilities between Western science and Native knowledge.
• Realize there are multiple perspectives for the same landscapes.


This activity is designed to give students hands-on experience with some of the concepts involved in the geologic explanations for the formation of mountains. Make sure you and students are familiar with the basic geology of Glacier NP, especially the vocabulary. For handouts, you can use the geologic story from the Student Reading Unit 2 (page 114 of Work House) and from the Rocks and Glaciers section of the park's website. There are also three levels of explanations on the Glacier NP website: mountains (short & basic); geologic formations (longer and includes thrust fault, stromatolites), and the resource guide on geology (longer and more detail). Have a variety of photo’s and maps of Glacier NP available for students to access. Lastly, view the Glacier's Geologic Story video. 


  • Watch the Instructional Faults Video and obtain the materials to set up the four stations in your classroom.
  • Create instruction cards for each station.
  • Student Reading, Unit 2, A Geological Story of Glacier NP. Page 114 of the Work House Program.
  • An assortment of various colors of 12 inch felt squares
  • Several 30 quart garbage bags
  • A bucket of clean sand
  • Several sheets of balsa wood, or a similar material (graham crackers can work), in various thicknesses and colors
  • A utility knife • Standard building blocks or 2” x 4” end cuts of various lengths
  • Glacier NP Student Resource Guide CD free by request, call 406-888-7800 or online with Rocks & Glaciers Fact Sheet and Digital Image Library has an assortment of Glacier pictures


  1. Discuss their homework (Student Reading, Unit 2) and have them work in small groups to share their answers for the “Checking for Understanding” questions. Did the students notice similarities between the Native knowledge and Western Scientific perspectives of how the mountains got their shapes?
  2. Watch Glacier's Geologic Story video to further explore the geologic perspective. 
  3. Demonstrate each of the stations and point out the instruction card for the geologic concept being modelled. Identify and define any new vocabulary.
  4. Have students rotate through each station and do the activities and discuss the dynamics that they demonstrate. Encourage them to experiment as long as they show interest and do appropriate activities. Don’t be too concerned about proper technical language. The students should feel free to apply their own vocabulary to facilitate communication skills. When appropriate, supply technical vocabulary and nomenclature but not to the point where students become hesitant to discuss the dynamics.

Station 1 - Deposition and down- warping
Ask a student to inflate a garbage bag, leaving about a third of the available air space unfilled, and tie the end tightly so that no air can escape. Lay the bag flat on the table and slowly pour sand in the center of the bag. The weight of the sand deposited like sediment will cause the surrounding area of the bag to rise while the center sinks. Pour the sand on several different areas of the bag. Facilitate student discussion of how this deposition on a shallow sea floor might affect the surrounding area.

Station 2 - Sedimentary Layering and Folding
Take a stack of felt squares and begin to lay them in successive layers on the table. If the presenter is familiar with the rock formations of Glacier Park, they may wish to lay down a succession of colors that correspond to the colors of formations in the park. Any series of earth tones will do just fine. You may want to cap your felt sandwich with a layer of blue or green to represent water or vegetation. Facilitate student discussion of the sediments that make up the materials for mountain building. Push the edges of the felt layered sandwich together as far as you can. This is an example of mountain formation by folding; even materials as soft as felt can only be folded so far before they are compacted as tightly as they can be. Certainly a great deal of folding was involved in the making of our mountains.

Some limited magma intrusions filled in space between rock layers and moved up through faults to form sills and dikes. Invite students to make suggestions about how they can demonstrate the intrusion of sills and dikes into your layered model.

Station 3 - Fault Blocking and Overthrust Slip
Make a short stack of balsa wood squares (could also use graham crackers and frosting). Have a student make an oblique cut through the materials. Have them push these layers together to demonstrate folding. The layers will pile up, shuffle, or even overturn. This is what happens in fault blocking dynamics when harder materials are compressed by plate tectonics.

Station 4 - Rifting
Pile several layers of various length building blocks together as if you were building a brick wall. Make sure that the bottom run is composed of your two longest blocks. Pull the two bottom blocks apart slowly until the upper layers collapse into the gap. This is known as rifting. Rifting occurs when subsurface intrusions spread the surface materials to the point of collapse, when tectonic plates pull apart, or in rare cases when surface materials happen to slough or slide across subsurface materials. The North Fork and Flathead Valleys are actually a kind of rift valley that has been partially refilled with sedimentary materials. For diagram of rifting, see Lesson 4, page 17 of Work House Unit 2.

Possible Extensions

  • As a review and a treat have the students bake a layer cake using mixtures of food color to represent the various sedimentary layers comprising the Glacier National Park rock formations. Instead of putting frosting on top, spray a large layer of whipped cream on a clean piece of stiff paper. Place the cake on top of the whipped cream. Place the edge of the stiff paper on the edge of a baking sheet. Lift the back edge of the paper slowly until the cake slides over onto the baking sheet. Cut and serve the cake and top it with the whipped cream conveyor surface. This little procedure gives a rough impression of how the Lewis Thrust Fault may have operated. For a healthier option, make a large hero sandwich with the class, using ingredients that suggest the appropriate and corresponding sedimentary layers in the park. Either activity will make a lasting impressions on the students.
  • Ask a local geologist to come and speak to the class about the geology of your area
  • Ranger-Led Field Trips and Service Learning Projects in Glacier National Park. Earth Science and Forest Processes field trips about park geology.
  • Self-Guided Field Trips as well as Guided Tours - various concession operated - in Glacier National Park.
  • Glacier Institute - geology and other education programs.
  • Flathead CORE - outdoor education guide for field trips in the Flathead.


Assessment Materials

Making pudding is a good activity that can be used to illustrate the role of Plate Tectonics in mountain building. Have the class make a pot of chocolate pudding. After the pudding is done, pour it in a shallow glass cake pan to cool. When almost cool, carefully use a sharp knife to cut the film that formed on top of the pudding into two equal portions. Carefully tilt the pan so that half of the pudding film slides up and over the other half of the pudding. The film represents the lighter continental crusts colliding and forming folded mountains. Even if the mountains collapse into a heap, the pudding can still be eaten by a hungry class.

See if students can identify geologic concepts they learned in the pudding activity.

Additional Resources

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Last updated: September 15, 2023