Seeing IS believing. Rocks are elastic!

The notion of rocks as elastic solids underpins many seismological concepts including the earthquake cycle and seismic wave propogation. This demonstration physically illustrates this property as students explore several rock/mineral specimens. The demonstration is somewhat discrepant because students' prior experiences suggest that rocks are hard and inflexible. Using this as a starting point, the demonstration begins with attempts to bend a large hand sample of granite or marble. Next, a large mica sample is deformed elastically. Finally, the elastic deformation of a long thin marble slab allows students to see and feel, that solid rocks are indeed elastic. During the discussion students are introduced to the concepts of stress and strain.


Students will be able to

  • Explain a method to demonstrate that solids, like rocks, can deform elastically
  • Describe, in a short paragraph, how the elasticity of rocks is fundamental to the earthquake cycle

Level: Novice

Share it

Related Lessons

Students collaborate in small groups to investigate how energy is stored elastically in rocks and released suddenly as an earthquake (the earthquake cycle). This activity emphasizes the role of mechanical models in understanding and testing ideas in science.

Lesson Novice

Related Videos

Demonstration shows that rocks are elastic by squeezing a slit core of rock.

Video Novice

Video lecture about elastic rebound and brittle material in the crust using a yardstick as a mechanical analog. This demonstrates elasticity, brittle fracture, and why it is difficult to predict earthquakes.

Video Novice

Related Animations

The Earth has 3 main layers based on chemical composition: crust, mantle, and core. Other layers are defined by physical characteristics due to pressure and temperature changes. This animation tells how the layers were discovered, what the layers are, and a bit about how the crust differs from the tectonic (lithospheric) plates, a distinction confused by many.

Animation Novice