Page 74 - Laboratory Manual in Physical Geology

A CTIVIT Y 2.3 Lava Lamp Model of Earth

Name: ______________________________________ Course/Section: ______________________ Date: ____________

A. Earthquake shear waves travel through both the crust and mantle of Earth. Such waves cannot travel through fluids (liquids,
gases), so rocks of both crust and mantle are mostly solid rock, not liquid rock. Yet Plate Tectonic Theory states that
lithospheric plates are made of rigid, stiff bodies of elastic-brittle rock (crust and lithospheric mantle) that rest on asthenosphere
and deeper parts of the mantle made of weak, ductile rock that flows like soft plastic or a viscous (thick) fluid. Explore how
solid rock can be rigid and stiff in the lithosphere but soft and fluid-like in the asthenosphere.

1. Obtain a piece of Silly Putty™ from your instructor. Perform the following tests on it, check the boxes to indicate whether
the test results characterize Silly Putty™ as a solid or a liquid, and answer the two questions.

Test Behaves like Behaves like
a solid a liquid (fluid)
1. Roll the Silly Putty™ into a ball and bounce it on the table.
2. Hold opposite ends of the mass of Silly Putty™, and pull it apart slowly.
3. Hold opposite ends of the mass of Silly Putty™, and pull it apart as fast as you can.
4. Roll the Silly Putty™ into a ball, then press down on it with your thumb.
5. Roll the Silly Putty™ into a ball, and allow it to sit for 2-3 minutes, or longer.
Under what conditions of pressure and time does Silly Putty™ Under what conditions of pressure and time does Silly Putty™
behave like a solid? behave like a liquid?

2. What is a rheid? Is Silly Putty™ a rheid?

3. REFLECT & DISCUSS How does your research on Silly Putty™ help explain how rocks may behave in the lithosphere
and beneath the lithosphere?

B. A “lava lamp” is inactive when the light is off, but a lighted lava lamp is dynamic and ever changing. Observe the rising and
sinking motion of the lava-like wax in a lighted lava lamp.

1. Describe the motions of the “lava” that occur over one full minute of time, starting with lava at the bottom of the lamp
and its path through the lamp.

2. What causes the “lava” to move from the base of the lamp to the top of the lamp? (Be as specific and complete as you can.)

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