Water can be a powerful force. We hear about floods and tidal waves in the news because they cause massive destruction in a very short time. But even an ordinary river can have a major influence on the land it passes through. Have you ever considered how the normal flow of a river can affect its environment over hundreds or even millions of years?
Up close, a river may look smooth and serene or dramatic and dangerous. What rivers do you know about? Is there a river near you or running through your city or state? Is the water crystal clear or brown with silt? Is it slow-moving or fast? What would the river look like if you could get a bird's-eye view? Is it curvy like a slithering snake? Is it "braided," with many sections separating and rejoining again?
Chances are, a river that you are familiar with looked different thousands of years ago. Rivers change in appearance over time because water erodes, or wears down, the soil and rock that forms their banks and bottoms. Through the power of erosion over millions of years, rivers can even create canyons that are thousands of feet deep!
Create Your Own Small-scale River
You certainly don't have millions of years to spend on a science experiment, no matter how much fun it is! However, using lightweight materials such as sand and cornmeal, you can be a hydrologist (water scientist) for a day. The "Go with the Flow: Model Rivers with Cornmeal, Sand, & Water" geology Project Idea shows you step-by-step how to create your own riverbed to imitate and observe the powerful force of erosion.
Consider these questions as your river flows: how does the speed of the water flow affect the erosion? Where do the eroded materials go? How do objects partially obstructing the flow of water change the erosion? What happens to the riverbed where there is a waterfall? What other questions can your students think of that setting up a model river and bank might help you explore?
You know it's going to be fun to create a river...what are you waiting for?
The Flow of Summer Science
Parents—this is a great, wet, opportunity for hands-on science with your students during the long hot summer!