Name:
Simulating Plasticity of the Mantle
(Lab Alternative)
Problem: Can a mixture have the properties of both a liquid and a solid? Yes or
No
Materials: 1 paper/plastic cup, cornstarch, paper towels, water
Procedures:
1. Put 2 spoonfuls of cornstarch into your cup. (Be careful not to crack the cups)
2. Slowly add water to the cornstarch while stirring with your finger.
3. Continue to add water until the mixture looks like a liquid but is hard to stir.
4. Pour the mixture into your hand being careful not to make a mess. (When in your hands, if the
mixture runs right out it has too much water. If the mixture comes out in a big clump, it has too
little water.) You should do this over an old newspaper to ease clean-up.
5. Experiment with your finger and the mixture. (all observations should be relevant to what you are
trying to determine in the lab)
a) What happens when you press fast and hard on the mixture?
b) What happens when you press slowly on the mixture?
c) What happens when you squeeze the mixture in your hand and then release your grip?
6. Clean up your work area.
Questions: (put your answers on the back)
1. Can a mixture have the properties of both a solid and a liquid? Explain.
2. How did pressure affect the mixture? Explain.
3. How do the changes in the cornstarch mixture compare with the plasticity of the Asthenosphere
which is located in the Earth’s mantle?
4. Why is the Asthenosphere said to have plasticity?
5. What causes the plasticity in the Asthenosphere?
6. How does this experiment help explain the belief that the Earth’s inner-core is solid?
Be sure to consult your notes and readings.