Brittle Vs. Ductile: Big Hunk as a Model for Earth's Crust & Mantle

3min 25s Novice

How can we model ductile rocks in the classroom?

Video lecture on how temperature controls mechanical behavior of materials, including rocks. A Big Hunk candy bar is used as a model for the behavior of materials in the lower lithosphere. The cold candy bar is brittle while the warm candy bar is ductile or plastic.

Dr. Robert Butler, University of Portland, OR shows that a material can be either ductile or brittle; temperature can control the mechanical behavior of a material; and a Big Hunk candy bar can be used as a model for the lithosphere

Keypoints:

Discovery

  • What is the difference between brittle and ductile?
  • How can a chewy candy represent the crust and the asthenosphere?
  • Does ductile material have earthquakes?
  • Why doesn’t the asthenosphere have earthquakes?
  • What happens when stress is applied to ductile materials?
  • What happens when stress is applied to brittle materials?

Related Videos

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

Related Lessons

A candy bar, made almost entirely from nougat, is a useful model for connecting strain in rocks to faulting (earthquakes) and folding.

Lesson Novice

In this activity students will evalaute Silly Putty and Oobleck, both of which demonstrate proprieties of both solid and liquids, as a potential concrete model for Earth's Asthenosphere.

Lesson Novice

We encourage the reuse and dissemination of the material on this site as long as attribution is retained. To this end the material on this site, unless otherwise noted, is offered under Creative Commons Attribution (CC BY 4.0) license