Download Graham Cracker Model of Plate Movements

Name_________________________
Period_______
Date:______________________
Graham Cracker Model of Plate Movements
Purpose: To study the interactions of the tectonic plates as they move slowly on the asthenosphere.
Background: The Theory of Plate Tectonics states that the crust of the earth is composed of 16 major pieces or
plates. These plates “ride” on the hot plastic upper mantle known as the asthenosphere. This theory also states
that these plates are in motion, creating a variety of interactions of plate boundaries. At plate boundaries, plates
may converge, diverge, or slip past each other in horizontal motion. In addition, some plates may appear to be
inactive.
In this lab, you will investigate the interactions that took place along the boundaries of different plates. You
will use a graham cracker model to help you learn about these terms:
Asthenosphere
Earthquakes
Collision
Faults
Convergence
Mountain building
Divergence
Subduction
Materials (per team): Two whole graham crackers, fruit roll-up, a cup of water, frosting, wax paper, plastic
knives or spoons.
Directions:
Part One – Divergent Plate Boundaries
1. Break a whole cracker into two rectangular pieces by following the perforations on the cracker.
2. Using the plastic knife or spoon, spread a thin amount of frosting (about the thinness of a playing card)
in the center of the wax paper.
3. Lay two pieces of graham cracker against one another on the top of the frosting.
4. To imitate the result of diverging oceanic plates, press down lightly on the crackers as you slowly push
them in opposite directions (apart). Do not push the crackers more than one centimeter apart.
Questions:
1. What happens to the frosting between the crackers?
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2. What do the graham crackers represent?
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3. What does the frosting represent?
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4. Where does this kind of boundary activity take place on the earth?
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5. What features are formed along the divergent boundary?
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Part Two – Convergent Boundaries (Continental and Oceanic)
1. Remove the graham cracker from the frosting (from Part 1). Break it in half. Now lay a quarter of a
whole graham cracker and the fruit roll end to end (against each other) on top of the frosting. The
graham cracker represents the thicker but less dense continental plate, while the fruit roll represents the
thin but dense oceanic plate.
2. Put the two “plate” models slowly toward each other and observe which plate rides up over the other.
On the actual surface of the earth, the lower plate is subducted.
Questions:
6. What type of plate does the fruit roll represent?
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7. What type of plate does the graham cracker represent?
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8. What happens when a pieces of crust is subducted?
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9. Where does this kind of boundary activity take place on the earth?
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10. What features are formed along the subduction zone?
_________________________ and _____________________________
Part Three – Convergent Plate Boundaries (Continental and Continental)
1. Break the graham cracker into four pieces- use only two and save the remaining two pieces of graham
cracker for Part four. Again, model the plate movement on top of the frosting.
2. Dip one end of each of the two graham crackers two centimeter (one inch) into a cup of water.
Immediately remove the crackers and lay them end-to-end on the frosting with the wet edges nearly
touching.
3. Slowly push the two crackers together, modeling the collision or convergence between two continental
plates. The wet ends of the crackers will curl and fold upwards as the crackers are pushed together.
Questions:
11. What does the graham cracker represent?
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12. In what way are the wet crackers more like the real plates than are
the dry crackers?
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13. What feature does the curling and folding at the ends of the wet
crackers represent?
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14. Where does this type of boundary activity take place on the earth?
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Part Four – Lateral (Transform) Plate Boundaries
1. Use the last two remaining graham cracker pieces for this part of the lab. Fit the two pieces together
end-to-end on top of the frosting on the wax paper.
2. Place one hand on each of the cracker pieces and push them together by applying steady, moderate
pressure. At the same time, also push one of the pieces away from you while you are pulling the other
toward you. If you do this correctly, the crackers should hold while you increase the push-pull pressure,
but will finally break from the opposite forces.
Questions:
15. Why is this movement often described as “horizontal sliding”?
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16. What famous fault is associated with this type of movement?
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17. Nothing happens at the beginning, but as the pressure is
increased, the crackers finally break as the pressure subsides. Explain how this is similar to the situation
in California along the San Andreas Fault.
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