SINKHOLE MORPHOLOGY AND DENSITY ON THE MITCHELL PLATEAU IN SOUTHERN INDIANA

Sinkholes form on the surface of karst topography when groundwater or rainwater dissolves limestone, creating surface depressions. On the Mitchell Plateau, most sinkholes are solution sinkholes, with a smaller number classified as collapse sinkholes. This project focuses on examining sinkhole morphology to determine its relationship with limestone units on the Mitchell Plateau. Our hypothesis is that sinkhole density and size are directly correlated with limestone purity. We used 1 meter resolution digital elevation models (DEMs), and ArcGIS Pro to map and measure sinkhole dimensions and density per square kilometer. XRF analysis was used to analyze the composition of the limestone to find the highest concentration of calcium carbonate. Dimensional data from the 7.5-minute topographic maps of Paoli, Crandall, Mitchell, Corydon East, Laconia, Bedford, and Fredericksburg, IN. were compared to the ArcGIS data. The average sinkhole length is about 87 m (285 ft), the average width is 62 m (203 ft), and average depth is 4 meters (14ft). The highest sinkhole density, measured at 108 per square kilometer, was found in northern Fredericksburg, IN. Conversely, the lowest sinkhole density, at 32 per square kilometer, was recorded in the southern Mitchell, IN quadrangle, both areas mapped on a 7.5-minute topographic map XRF results show that St. Louis has the highest CaO3 of 93.55% followed by the Salem and St. Genevieve limestones at 91.70% and 91.37% respectively.