Name/Title
S07.04.012Description
The Keyhole is a natural tunnel of resistant Silurian Geologic Period Peebles Dolomite in the Fort Hill Earthworks and Nature Preserve, Highland County, Ohio. The Natural Arch and Bridge Society defines a natural arch as “a rock exposure that has a hole completely through it formed by the natural, selective removal of rock, leaving a relatively intact frame.” The image was an entry in 1984 Ohio Geology Slide Contest.
Information taken from Ohio’s Natural Arches by Timothy A. Snyder (Ohio Geological Survey, Education Leaflet No. 18, Revised Edition, 2014) and Rainbows of Rock, Tables of Stone: The Natural Arches and Pillars of Ohio by Timothy A. Snyder (McDonald & Woodward: Granville, Ohio, 2009) and Natural Bridges in Ohio by Michael C. Hansen (Ohio Geological Survey, Ohio Geology Newsletter, Summer 1988).
This slide image included in the USGS National Digital Catalog for NGGDPP Grant G15AP00115 in FY2015.Context
Sideways picture of tunnel opening between two rock outcrops. The Keyhole at Fort Hill Earthworks and Nature Preserve.