Activism > Environment Summary. The Devonian Fossil Gorge at the Coralville Reservoir in Iowa is a beautiful and ancient natural resource. When you visit the Devonian Fossil Gorge, it’s likely you’ll see other people there as well because of the popularity of this natural phenomenon. Video. Below is a video showing the Devonian Fossil Gorge… Continue reading Devonian Fossil Gorge Coralville Reservoir Iowa Video