Earth 26

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Weathering Erosion & Rivers

In earth science, erosion is the action of surface processes (such as water flow or wind) that remove soil, rock, or dissolved material from one location on the Earth’s crust, and then transport it to another location. Rivers of the world are a significant factor in erosion. Rivers exert hydraulic action – a force of the river against the banks can cause air to be trapped in cracks and crevices. Rivers also exert abrasion – rocks carried along by the river wear down the river bed and banks. Erosion and weathering are not the same thing. Weathering does not include movement. Weathering is the breaking down of rocks, soil, and minerals as well as wood and artificial materials through contact with the Earth’s atmosphere, water, and biological organisms

Lesson 1 (or “Day 1”) Material
Lesson 2 (or “Day 2”) Material
Lesson 3 (or “Day 3”) Material
Lesson 4 (or “Day 4”) Material

4:05 Weathering and Erosion: Crash Course Kids #10.2

6:00 The journey of a river from source to mouth

2:68 Why Do Rivers Curve?


Compare Contrast and Debate


Adapted from: Spector, J. (November 23, 2015) “The Untapped Potential of America’s Hydroelectric Power.” Retrieved from

Constructing new dams is highly difficult. Constructing new water dams requires a lot of money.  New dams could do a lot of damage to a river’s ecosystem. Most existing dams in the U.S. do not produce electricity. More than 90 percent of U.S. dams do not produce electricity. That totals about 80,000 dams that do not produce electricity.  These dams hold back water, which can be useful for things like flood control, irrigation, and navigation.

Retrofitting some of the existing 80,000 dams could produce up to a total of 12 gigawatts of new hydropower. That amount would be about 15 percent of current hydropower capacity. That amount would be equal to about half of all U.S. solar.

Making these projects viable would require ecological studies, infrastructure investment to transport electric energy into the grid, possible negative impacts on wildlife and endangered species, and a sizable investment through tax-payer dollars.

  • Position A: Use of existing dams as a way to increase hydro-power should be a high priority of local governments and the U.S.  Department of Energy.
  • Position B: Problems and obstacles of retrofitting non-electric producing dams into hydro-power dams outweigh the potential benefits.

Resources Documents and Links

Special Notes and Notices

Instructor Emphasis:

  • Science & Engineering Practice: Use mathematical and computational thinking.
  • Cross-Cutting Concept: Stability and Change.

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