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Go With the Flow Activity

Included with permission from Yellowstone Teacher's Guide, An Education Resource for Teachers, Destination Cinema, Inc., 4155 Harrison Boulevard, Suite 210, Ogden, UT 84403, http://www.destinationcinema.com

Objective: Students will experiment with a simulated river bed and learn that erosion takes place faster with a young, fast-moving river than with a slow, older river.

Materials: A milk carton (quart size), fine, dry soil, plastic tub, watering can with a diffuser top, empty mayonnaise jar, ruler, funnel with a wide hole

In the film: The Grand Canyon of Yellowstone is a spectacular geologic example of how a river can erode the earth to expose colorful rocks and minerals. The power of the river can be seen as it makes its forceful way down the river valley, over two waterfalls, and finally into Yellowstone Lake.

Background: A river valley is often created by a large amount of water that has raced downhill (usually from the runoff of a snow cap or glacier). The water will race down a steep slope and will erode river walls faster than it will on a gently slope. Rivers with steep sloping riverbeds, and fast moving water are referred to as "young" rivers. This means that the water is still actively eroding the canyon walls, taking dirt and rocks quickly downstream in the center of the valley. Rivers with gently sloping riverbeds, containing slow moving, meandering water, are said to be "mature" rivers.

To Do: Cut the milk carton length-wise, making the pour spout into a funnel shape and opened slightly. See diagram. Fill the milk carton with dirt, leaving 1/3 of an inch of the carton exposed above the dirt. With the pencil, make a groove down the center, the length of the soil. Set the carton at a slight slope, with the plastic tub at its base. j Fill the watering can with water and from an height of about three feet, sprinkle the soil at the top of the slope for 30 seconds. A "river" will flow down the groove into the tub carrying the soil with it. Wait for the muddy water to stop flowing into the tub then pour all of the water and soil from the tub into the glass jar, using the funnel to make sure nothing is spilled. Let the soil settle in the jar and measure the depth of the soil deposited with the ruler. Record the measurement.

Wash out the milk carton, the jar and the plastic tub and repeat the activity this time placing the carton of dirt at a much steeper slope. Again sprinkle the top of the dirt, from a height of three feet, for 30 seconds, the steeper slope will make a "river" that flows more quickly. Again allow the muddy water to stop flowing into the tub, and then pour the contents into the glass jar using the funnel. Allow this to settle and measure the amount of dirt in the jar. Has more dirt settled in the jar after the steeper "river" experiment?

Taking it Further:

1. After seeing the film, would you classify the Yellowstone River as a young or mature river? Why?

2. Build a large wooden box, fill it with dirt and create the "river valley." Place the box on a slope, and plant some grass on the banks of the "river." How does the grass affect the erosion?

3. Build two large "river beds" out of wood and create a working model of a young river and a mature river.