Subsurface geology of the Serpent Mound disturbance, Adams, Highland, and Pike counties, Ohio, by Mark T. Baranoski, Gregory A. Schumacher, Doyle R. Watts, Richard W. Carlton, and Belgasem M. El-Saiti. 60 p., 26 figs., 5 tables, 3 pls., 2003.
Report of Investigations 146 concludes that a 5-mile-diameter area of highly disturbed bedrock at the intersection of Adams, Highland, and Pike Counties is a deeply eroded crater formed by a meteorite impact approximately 250 to 300 million years ago. Named the Serpent Mound Disturbance after the famous prehistoric Native American effigy located near the southwestern edge of the area, this disturbance is the single-most complex geologic structure exposed at the surface in Ohio. An investigative team made up of geologists from the ODNR Division of Geological Survey and geologists formerly of the University of Glasgow (Scotland) became convinced of the structure's impact origin after recognizing rock and mineral features unique to impact craters in rock cores collected from the site in the 1970s. The team also recognized evidence of an impact crater in geophysical surveys and remote satellite imagery for the area. Paleomagnetic analyses of rock samples recovered from the drill core indicate the impact of the meteorite occurred during the Permian Period (about 250 to 300 million years ago), when continents were fused together into a single supercontinent called Pangea and the area of present-day Ohio lay just south of the equator.