Download Case of the Split Personality Lab #20

Case of the Split Personality Lab #20
Objective: Use a model to simulate the physical properties of the asthenosphere and the
movement within it.
Background:
Beneath the lithosphere (the solid crust and upper part of the upper mantle) is a layer of
Earth called the asthenosphere that has unique physical properties. The material of the
asthenosphere acts as a solid when conducting earthquake waves but also a liquid or
gas. Due to these unique properties and convection currents the plates move.
Materials:
1/4th cup corn starch
baby food jar
water
paper towels
(Write the procedure/data collection title in your lab notebook and answer the bolded
questions as you work through the lab.)
Procedure/Data Collection:
1. Mix 1/4th cup of corn starch in a baby food jar with enough water so that the
mixture forms a thick paste as you stir with your finger. Pour the mixture on your
lab table.
2. Does the mixture act as a solid or liquid when you pour it? (Answer in
your notebook)
3. Tap the mixture.
4. Does the mixture act as a solid or liquid when on the table? (Answer in
your notebook)
5. Pick up the mixture and roll it into a ball. Notice how it reacts when you stop
rolling it. Place the mixture into the jar. Now slowly push your finger into the
mixture.
6. Does it act more like a solid or liquid when you push into it?
7. What conditions change the physical conditions of the mixture?
8. What conditions in Earth could change the physical characteristics of
the rock?
9. Clean up your entire island and workspace. Have your instructor sign/stamp your
lab notebook to obtain points for the activity.
Analysis:
1. Describe how the properties of the asthenosphere allow plate movement. (Refer
to the lab, notes and textbook pg. 235)
2. Explain what convection currents are by sketching and labeling a picture of
convection current movement within the asthenosphere. (Refer to your handout
on convection currents)
3. Read about the two models of mantle convection on pg. 270 of your textbook.
Explain each model and summarize ultimately what drives plate motion.