Floods Reveal Devonian Fossil Gorge

The Devonian Fossil Gorge is located near the Coralville Dam and is over 375 million years old. An ancient fossilized sea floor ecosystem dominated this period evidenced by stems from the Crinoids, complete Brachiopods, and sparkling calcite (calcium carbonate; CaCO₃) in limestone. The gorge was revealed during the devastating floods of 1993 when the emergency spill-way at the Coralville Dam topped over. The floods sent a torrent of water down the hillside, eroded the landscape, and revealed the Devonian Fossil Gorge.

• What evidence does the geologist show us to support the idea that these organisms lived long ago?

• What can fossils help us understand about organisms (living things) that lived long ago?
• Why do humans study fossils? How do fossils of extinct organisms relate to today’s living organisms?
• What might the environment have been like for the organisms mentioned in the video (Crinoids and Brachiopods)? Examples might include grasslands, tropical, arctic, marine (water), desert (dry) etc.

Students could:

• Take notes of the causes and effects they hear about during the video (Example: cause is flooding, effect is reveal of fossils).
• Brainstorm what fossils are, where they come from, and why they are important. Then, watch the video and add to their ideas.
• Research the fossils mentioned in the video (Crinoids and Brachiopods). Research might include physical description, habitat, food source, etc. 
• Compare the living things from the past (as evidenced by the Devonian Fossil Gorge) to the things currently living in the area to demonstrate change over time.

• Iowa PBS | Devonian Fossil Gorge: Iowa by Air this video contains a flyover view of the prehistoric discovery, Devonian Fossil Gorge, in Coralville.
• PBS LearningMedia | Iowa PBS Iowa Land and Sky: Geology: This is a resource for educators including an Iowa Geology storyline with driving questions, anchoring phenomena, and sequence of instruction.  
• LiveScience | Devonian Period: Climate, Animals & Plants: Background on the climate and geography, Marine life, Plants, Animals, and Mass extinction.