Modeling Landforms
You created models to understand how weathering and erosion work. Now let’s see how those processes shape different structures on Earth.

Estimated time to complete: 2 hours

You will need the following materials:

a cake pan
a spatula
a pen
a cup
12 tooth picks
10 cups of sand
water
a spray bottle with water
a textbook
Hypothesis and Data Collection: Creating a Seacoast
Part A
Place half of the sand at one end of the cake pan and water in the rest of the pan as shown in the image. Write down your prediction of what will happen when you use a spatula to repeatedly push the water toward the sand.

a cake pan with sand at one end and water in the rest of the pan with a spatula pushing the water

Part B
Now, use the spatula to push the water toward the sand. Repeat this action several times and observe what happens. Pay attention to the layers of sand. Then write down your observations.

Hypothesis and Data Collection: Creating a Riverbank
Part C
Shape the sand so it fills the entire bottom of the pan and level it with the spatula. Add more sand as needed. Use a pen or other tool to carve a winding river in the sand that spans the entire length of the pan. Write down your prediction of what will happen to the sand when you pour water into the river.

Part D
Using a cup, carefully pour water into the river, allowing it to flow from one end to the other (if needed, prop one end of the pan on top of the textbook to give it slope). Observe what happens to the sand as the water flows down the river and write down your observations.

Hypothesis and Data Collection: Mountains
Part E
In the cake pan, push moistened sand together in the shape of a mountain. Be sure the sand is wet enough to stick together so it does not crumble. You could also invert the cup and shape your mountain around the cup.

Next, stick 10 to 12 toothpicks into the right half of the mountain. Keep the left side empty. In part F, you will spray water on the mountain using the water spray bottle. Predict how the toothpicks will affect the rate of erosion.

Part F
Now spray water all over the mountain and write down your observations. What happens to each half of the mountain?

Analyze and Extend: Creating a Seacoast
Part A
In the seacoast model, if this were Earth’s surface, what does the water’s motion represent?

Part B
What changes did you observe in the sand as you pushed the water toward it?

Part C
Sea caves are formed by the motion of the sea. Does your seacoast model show how these caves might have formed? Explain your answer.

a cave by the sea

Analyze and Extend: Creating a Riverbank
Part D
What did you observe when you poured the water into your river?

Part E
How could erosion affect humans and wildlife that live near the river? Explain your answer.

Analyze and Extend: Mountains
Part F
Based on the mountain experiment, why are mountains narrower at the top than at the bottom?

Part G
What did you observe when you poured water on the mountain? Were there any differences between the side with the toothpicks and the side without?

Part H
Based on your observation in part G, do you think trees on a mountain increase or decrease the rate of erosion? Why?

Part I
Does the mountain model support the idea of preserving vegetation in areas affected by high rates of erosion? Explain.