The faults and folds in rocks provide evidence that the rocks are subjected to compressional, tensional, and/or shear stress.
Students begin this activity by experimenting with Silly Putty™ to identify different stresses that rocks can experience, and examining the relationship between stress type and strain. This lays the foundation for students to understand that the structure (strain) we see in rocks provides evidence for they type of stress that caused it. Students apply this idea by examining images of faults and folds to determine how the structures formed. Additional evidence is collected through experimentation with sponge models. Students summarize their ideas and evidence for each image in a short written paragraph or in alternative presentation format. Sponge models are particularly useful because they allow students to interact physically with the models to consider the forces necessary to create these features as well as visualizing deformation in 3-D. Sponge models can be constructed using inexpensive materials obtained from a dollar store or any home improvement store.
Students will be able to:
- Use foam models to demonstrate the forces and relative motions of a block of rock to form of anticlines and synclines.
- Use foam models to demonstrate the forces and relative motions acting on blocks of rock to form normal, reverse and strike-slip faults.
- Use evidence to support or refute the claim made in an argument.