EVALUATING THE POROSITY AND ROCK STRENGTH OF CARTER COUNTY, KY

Carter Caves State Resort Park (CCSRP) located in, Carter County, KY, is a fluviokarst system consisting of 106 km² deeply incised valleys characteristic of the Cumberland Plateau. Stratigraphically the region consists of approximately 25m of Mississippian age limestone of the Slade Formation overlain by the lower Carter Caves sandstone member of the Mississippian Paragon Fm. Over the course of the last decade, numerous studies conducted terrain analyses to characterize CCSRP for cave collapse, paleoclimate data, and evolutional history. These studies have primarily focused on the use of digital elevation models (DEM) and GIS driven techniques to identify and correlate cave levels to stream incisions.This region lacks numerical descriptions of in-situ parameters, such as porosity and rock strength, that are commonly used as components in hydrogeologic and karst genesis models. There has been minimal efforts completed to conduct or advance any research in porosity in recent time. Ultimately, this has limited the ability and domain to which further advancements in characterizing CCSRP could be done.

Two samples of the Warix Run member and five samples of the Mill Knob member of the Slade formation were collected near the entrances to Horn Hollow cave. The Mill Knob member consists of light-olive-grey quartzose calcarenite and lesser calcilutite, while Warix Run contains calcarenite and calcilutite with lesser amounts of dolomite and shale. In general, both also contain medium- to coarse-grained red and grey chert, silt, and sand with large crossbedding. All locations were evaluated for rock strength using a Schmidt hammer, and four samples were evaluated for porosity. Thin sections of these samples were acquired and applied with a blue dye epoxy to enhance the visibility of any pore spaces. Using ImageJ and INFINITY ANALYZE 7 , 25 images at 4x magnification of each slide were digitized to calculate the average porosity of each sample as well as a cumulative average for both geologic members. The porosity data for Mill Knob displays a mean of 5.05%, with a range from 3.16% to 6.62% while the Warix Run sample had a porosity of 2.63%. Rock strength data for Mill Knob shows a mean of 28 5 n/mm², with a range from 21.5 to 42 n/mm² while Warix Run had a strength of 26.25 n/mm².