Plate Boundaries

Questions to Ponder

1. How does the crust move at the ridges and trenches around the world?

2. What happens to the crust as a result of that motion?

Simulating Plate Interactions - lab

• In this activity you will use modeling clay to simulate the different ways that plates interact with each other.  

• Pay attention to what happens to each block as you push, pull, and slide the clay.  Especially pay attention to the edges of the clay.

Materials

• 2 flat blocks of clay (approximately 2cm x 5 cm x 10 cm) 

• 1 plastic tray or plate

• data table 

Procedures

1. Lay two blocks of clay flat on the tray about 5 cm apart. Push them together using steady, firm pressure. Continue pushing until you notice any changes in the clay.  Record your observations on your data table on line 1.  Draw diagrams of the clay to show what happens to the blocks. Be sure to sketch all parts of the clay block.  For now, leave the name column blank.

2. Reshape the blocks and place them side by side so they are touching.  Slide them sideways past each other in opposite directions. Sketch the blocks and draw arrows to show how they are sliding past each other. Record what happens to the clay and describe how it feels as the blocks are sliding past each other. Record your observations on line 2. 

3. Use one clay block and pull on it from opposite ends. Observe the middle of the clay as you are pulling. How is the middle of the clay block changing? What happens as you continue pulling? What if you pull with more force? Record your observations in your notebook.  Draw a diagram of what your block of clay looks like once you stop pulling. 

Wrap up

• Look back at the diagrams that you created while you simulated the different plate interactions.

Discuss the following with your team

1. What kind of geologic activity do you think results from the different plate interactions?  (Remember, geologic activity could be earthquakes, volcanoes, mountain building, trenches, etc.)  

2. As a team, label the diagrams in your notes with your predictions.  For example, you may think that one or more of the interactions results in earthquakes on the surface.

Gizmo Warm-up 

1. To begin, turn on Show labels. What are the layers of Earth that you can see?   The lithosphere is a layer of rigid rock that consists of the crust and the upper part of Earth’s mantle. The asthenosphere is a layer of the mantle that can deform like plastic.

2. Turn on Boundary name, and click on each boundary. What four boundaries do you see?

Activity B: Colliding continents 

Get the Gizmo ready

• Turn off Boundary name

Question: What happens when two continents collide?

1. Observe: Boundary B is an example of a convergent boundary, where two plates are moving toward one another. When the two converging plates both contain continental crust, it is called a collision zone. 

   • Click the left arrow four times to see how the plates move. 

   • How would you describe the motion of plates in a collision zone?

2. Sketch: Draw a side view of the plate boundary before and after the plate motion. Draw an arrow to show which way the plate moved.

3. Locate: Turn on Show location. Where on Earth can you find collision zones?

4. Highlight these locations on your map.

Activity C: Oceanic crust meets continental crust 

Get the Gizmo ready

• Turn off Boundary name

Question: What happens when ocean crust collides with continental crust?

1. Observe: Boundary C is another type of convergent boundary called a subduction zone. 

2. Click the left arrow four times to see how the plates move. 

   • How would you describe the motion of plates in a subduction zone? 

3. Sketch: Draw a side view of the plate boundary before and after the plate motion. Draw an arrow to show which way the plate moved. Before movement After movement

4. Locate: Turn on Show location. Where on Earth can you find subduction zones?

5. Highlight these locations on your map.

Activity D: Spreading plates 

Get the Gizmo ready

• Turn off Boundary name and Show location.

• Select BOUNDARY D. 

Question: How is new crust formed?

1. Observe: Boundary D is a divergent boundary. Click the right arrow four times to see how the plates move. How would you describe the motion of plates in a divergent boundary?

2. Sketch: Draw a side view of the plate boundary before and after the plate motion. Draw an arrow to show which way the plate moved. Before movement After movement

3. Locate: Turn on Show location. Where on Earth can you find divergent boundaries?

4. Highlight these locations on your map.

Diagram

Draw a Diagram of the different plate boundaries in your notebook.  Be sure to label all of the parts!  Your diagram should include the following labels:

• continental crust

• oceanic crust

• boundary

• convergent boundary*

• divergent boundary*

• transform boundary*

• subduction zone*

• trench*

• magma

• seafloor spreading

• mid-ocean ridge*

• rift

• fault