Activity 4: Power of Water

Erosion is the process when a rock particle is moved by some flowing agent such as air, water or ice. Erosion may be very slow to very rapid, depending on the soil, the local landscape, and weather conditions.

The Potomac River played an important part in the water systems along the Canal. Water erosion wears away the earth's surface. The Great Falls in Virginia and Maryland is a great example of the power of water erosion!

 

Power of the Potomac River

Next to the Potomac River and along the 184.5 miles of the towpath, there are 261 perennial streams, 4 water bodies (Little Pool, Big Pool, Seneca Swamp, Widewater), and about 54.4 miles of watered canal. These water systems are extremely important to the C&O Canal, both during its operation and today as a National Park. Although flooding has been challenging for the C&O Canal in the past, it is a natural process that has shaped and reshaped the Potomac River Valley for a long time.

 

View of rushing Potomac River at Great Falls.

NPS Photo

 

View at Widewater (MM13). Canal widens from narrow hand dug bed to ancient Potomac River channel.

NPS Photo / Nanette Nyce

Signs of Water Erosion

• Exposed tree roots
• Cracks in the soil in a river bank
• Clumps of grass in the river
• The top part of the river bank overhangs
• Brown or coloured water
• Collapsed river bank

Visit your local river or stream and see how many signs of water erosion you can spot!

 

Oxbow lake formation in a meandering stream.

NPS Geologic Resources Division / Phil Reiker

Activity: What happened at Widewater?

At Mile Marker 13, you'll see an abandoned channel of the Potomac River. A meandering stream has a single channel that winds snakelike through its valley.

Meanders change position by eroding sideways and slightly downstream. As water flows around these curves, the outer edge of water is moving faster than the inner.

This creates an outer edge (a cut bank) and a surface on the inner edge (a point bar). Where the bends of two meanders meet, they bypass the curve of river, creating an oxbow lake.

Directions:

1. Visit the Kids and Youth Widewater page and read about how the Potomac River and water erosion created Widewater.
2. Using your Junior Geoscientist Activity Log and the diagram to the left, reflect on What happened at Widewater?
3. Visit the following links to get learn more about the Power of Water:
   (a) US Geological Survey Erosion Simulation Video
   (b) NPS Article Meandering Streams
4. Continue to next activity after finishing.

 

Relevant Links

• C&O Canal National Historical Park | Rivers and Streams
• National Park Service | Erosion Subject Page
• National Park Service | River Systems and Fluvial Landforms

 

Junior Geoscientist Main Page