Activity 6: C&O Canal Geologic History

Rock formations exposed by the erosive force of the Potomac's flow provide a window into the continent's geologic past, a time when North America collided with continents that now lie across a vast ocean. Some of these rock formations were originally formed at the bottom of the sea!

The Potomac River showcases other geologic features and processes, including the Great Falls of the Potomac, fossils, and natural habitats such as bedrock terraces and river scourbars formed by the shifting sands of geology.

 

NPS Photo

Geologic Time Scale of the C&O Canal

Closely examine the Geologic Time Scale diagram for the C&O Canal. You will notice that are different eras (precambrian = oldest) and periods within each era. The age of each of these events go back millions of years!

The information used to create a diagram like this was created by people studying the geology and paleontology in the C&O Canal and neighboring areas. Fossils and geologic discoveries build on the rich history of the Park.

Explore Fossils by Era

• Precambrian
• Paleozoic
• Mesozoic
• Cenozoic

 

Karst and Caves

Karst landforms (sinkholes and caves) can be found throughout the C&O Canal. You can find these landforms in areas underlain by limestone, dolomite, and marble in the Valley and the western Piedmont province. Learn more and view stunning photos of karst and caves across the National Park Service!

 

Explore Even More Park Landforms

• Aeolian (Dunes) Landforms
• Arid & Semi-arid Region Landforms
• Beaches & Coastal Landforms
• Glaciers & Glacial Landforms
• Karst Features & Landforms
• River Systems & Fluvial Landforms
• Tectonic Landforms & Mountain Building
• Volcanic—Extrusive Igneous Landforms
• Volcanic—Intrusive Igneous Landforms

 

Rock Talk Activity: Geology Conversations on the C&O Canal

One of the best ways to really enjoy and learn about the C&O Canal geological history is to experience it in-person! For this activity we invite you to the Park and reflect on the natural land formations in front of you.

1. Visit the Kids and Youth Rock Talk page for a rich overview of areas of geologic interest throughout the Park.
2. After reading more about the geology of each location, visit the site in-person with family or friends.
3. Think about the geological history and geodiversity in the area. What kinds of ancient animals would you have seen here? What types of plants and trees would fill the Park?
4. Use the Junior Geoscientist Activity Log to record some of your reflections as you continue your Geology Conversations on the C&O Canal.
5. Congratulations! You've completed your last activity of the Junior Geoscientist virtual program. Return the Main page and retrieve your completion certificate.

 

Generalized Geological Map of Maryland. Click map to enlarge image.

Maryland Geologic Survey

Rock Talk Outline

• Olmsted Island
• Locks 15-20
• Widewater
• Lamprophyre Dikes
• Pothole Alley
• Purplehorse Beach
• Mather Gorge
• Devil’s Eyebrow
• Paw Paw Tunnel

 

Junior Geoscientist Main page