Name/Title
S04.02.013Description
Photomicrograph of sedimentary quartz grain in sample SM1-36 taken from breccia in core DGS 3274 at a depth of 1,436 feet (438 meters). The quartz grain has planar deformation features (PDFs), which appear as dark lines within the grain. This quartz grain exhibits two sets of planar deformation features. These features form under considerable pressure. The quartz grain was recovered from a rock core in the center of the disturbance. The quartz grain is less than one-fourth of a millimeter in diameter.
Richard W. Carlton discovered the quartz grains in the core, which conclusively proved the structure was affected by an asteroid or comet impact. The grain-mounted thin section was photographed in transmitted light with gypsum plate and crossed nicols. Discussion of the seven PDF samples appears in 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 (Report of Investigations No. 146) published by the Ohio Division of Geological Survey in 2003. The sample was collected and photographed by Richard W. Carlton in 1998.
The Serpent Mound Impact Structure is an approximately 9-mile-diameter area of highly disturbed and structurally deformed bedrock at the intersection of Adams, Highland and Pike counties. The area of the impact structure has dolomite, shale, limestone, sandstone, and siltstone lithologies. Because of the geologic forces that have acted on the site of the impact crater, bedrock in the area is a mixture of uplifted, down dropped, faulted, folded and eroded rock from the Ordovician, Silurian, Devonian and Mississippian Geologic Periods. The deeply eroded crater is believed to have been formed by an asteroid or a comet impact approximately 250 to 300 million years ago. It is named the Serpent Mound Impact Structure after the prehistoric American Indian effigy earthwork located near the southwestern edge of the area. It is the single-most complex geologic structure exposed at the surface in Ohio. Investigation of the impact structure has been done using rock cores, seismic data, geophysical surveys and remote satellite imagery for the area.
This slide image included in the USGS National Digital Catalog for NGGDPP Grant G15AP00115 in FY2015.Context
Multicolor and microscopic view of rock quartz grain; looks similar to tie-dye. From Serpent Mound Impact Structure.