Devonian Fossil Gorge – Coralville Lake, Iowa
Devonian Fossil Gorge – Coralville Lake, Iowa was discovered in 1993 when the flood abated, the eroded Gorge surface revealed a succession of 375 million year old bedding planes with diverse and abundant fossils commonly standing out in relief. Devonian Fossil Gorge soon emerged as the name for the feature.
Interpretive exhibits line the Entry Plaza, an open observation platform whose hexagonal outline reflects the symmetry of the abundant colonial coral Hexagonaria. Bedding plane bounded monoliths of Silurian Anamosa Stone dolomite that border the Plaza are 6 feet wide, 18 inches thick, and up to 15 feet high. Handicap-accessible walkways lead from the Entry Plaza to an adjacent Overlook Plaza, and down to the Biostrome Plaza near the Gorge floor. The Biostrome walkway is lined by a succession of 16 massive Cedar Valley slabs, taken from adjacent quarries, arranged in original stratigraphic succession. Construction of pathways within the Gorge has been avoided, but 20 “discovery points” are marked by numbered hexagonal metal plates: maps and explanatory brochures are provided.
Devonian Fossil Gorge is an invaluable resource for communication of the methodology of science. Evidence that the Midwest was once a shallow tropical sea, south of the Equator and teaming with life, can be presented convincingly, as can concepts such as geologic time and plate tectonics.
Location: Devonian Fossil Gorge is at the end of the Emergency Spillway at Coralville Dam, 2850 Prairie du Chien Road, N.E., Iowa City, Iowa
Phone: 319-335-1580 (Iowa Groundwater Association)
Open: Year around