Academic Ninth Grade Science

On Earth, there are 3 main types of plate boundaries. These help to shape the way our planet looks as well as to recycle the crust. These plate boundaries are responsible for many geologic features we see and experience. Today, you will use food items to represent the different plate boundaries.

Objective: To determine how the different plate boundaries function

Key:

Item / What it represents
Frosting
Graham Crackers
Fruit Roll Ups

Procedure:

1. Demonstration of a divergent plate boundary

A. Break a whole cracker into two square pieces.

B. Lay the two squares against each other on the frosting on the plate.

C.  To model the result of diverging oceanic plates, gently press down as you slowly

push the two squares in opposite directions, away from each other. The opening between the crackers need not be greater than one centimeter.

·  The frosting should well up on the space between the crackers imitating what occurs at the mid-ocean ridges along diverging crust plate boundaries.

D.  Make a diagram of your observations on your data sheet.

2. Modeling the convergent plate boundary between oceanic and continental plates

A. Lay a whole cracker and the fruit roll up end to end on your desk. The fruit roll up represents the thin but dense oceanic plate while the graham cracker represents the thicker but less dense continental plate.

B. Push these two “plates” together and watch which plate rides up over the other.

C.  Make a diagram of your observations on your data sheet.

3. Modeling the convergent boundary between two continental plates

A. Use the two remaining quarters of the cracker.

B. Lay them end-to-end on the desk with the wet ends nearly touching.

C. Slowly push the two crackers together.

D.  Make a diagram of your observations on your data sheet. (How would it be different if they were wet? Would they bunch upwards in the center?)

4. Modeling the transform (strike-slip) boundary

A. Carefully break your cracker in four pieces.

B.  Fit 2 of the pieces back together side by side and set the other two aside for later.

C.  Put one hand on each cracker piece and apply steady pressure pushing them together. As you do this, push one piece away from you and pull the other toward you. If you do this carefully, the cracker will hold while you increase the push-pull pressure then will finally break from the opposite forces.

D.  Make a diagram of your observations on your data sheet.


Data:

Boundary / What did it look like? / Direction of movement / Facts to remember
1.  Divergent
2.  Continental-Oceanic Convergence
3.  Continental-Continental Convergence
4.  Transform

Analysis Questions:

1. What happens to the frosting and the fruit roll ups at a divergent boundary?

2. What geologic process is represented between the frosting & fruit roll ups in the first model?

3. What happens between the fruit roll up and the graham cracker in the second model?

4. What is subduction? What feature forms where subduction occurs?

5. How did model 2 demonstrate subduction?

6. Why is the oceanic plate subducted?

7. What happened between the graham crackers in the third model?

8. What features are formed when 2 continental plates converge?

9. What happened between the graham crackers in the fourth model? Did they move easily or was there resistance?

10. What occurs at transform boundaries?

Conclusion: What was learned about the plate boundaries? How does density play a role in plate tectonics? Elaborate on all learning through this experience and other class activities dealing with plate boundaries. Provide facts and details that indicate a complete and thorough understanding of how plates move and how each plate boundary works.