DISTRIBUTION, FORMATION, AND CLASSIFICATION OF NATURAL ROCK OPENINGS IN KENTUCKY

Natural rock openings are an iconic attraction for people who enjoy hiking or photography while providing tourism opportunities in economically depressed areas. Importantly, natural rock opening formational processes can provide insight into the fluvial history and landscape evolution of an area. While natural rock openings in the western United States have been well studied, rock openings east of the Rockies have received less attention with formation processes being poorly understood. Moreover, natural rock openings have non-standardized and complex naming schemes based solely on morphology. Kentucky contains the second largest number of natural rock openings in the U.S. with many being located in areas underlain by jointed, cross bedded sandstone and limestone. In this study, we confirm traditional formational controls of rock openings (including headward erosion of stream valleys, running water (streams or rivers), dissolution from seeping water, and roof collapse), their inter-relationships, and their relative importance. Landscape position can be used as a proxy for time and implies the opening forming in stream valley are younger than those found at higher elevations and abandoned by contemporary fluvial regime during base level drop. To accurately convey this information, we develop a classification scheme based on formation processes and the spatial relationship between openings, bounding joints, and landscape position, which are conducive for time-space substitution analysis and understanding evolution of rock openings over long timescales.