Analysis of the Pennsylvanian Vanport Limestone at Jack Critchfield Park, Slippery Rock University

Located beyond left field at Jack Critchfield Park, lies a rock outcrop of the Pennsylvanian-aged Vanport Limestone that provides evidence of a paleoenvironment that existed over 300 million years ago. The Vanport Limestone is an extensive geological unit that can be found regionally across western Pennsylvanian and into Ohio. It is commonly mined in the area and used as an aggregate for construction projects and as a component in cement. Investigation of this rock outcrop at Slippery Rock University has provided a detailed picture of the life that existed within a unique marine environment during this time. Detailed examination of the rock outcrop as a whole, hand samples, and thin sections has allowed us to understand the sedimentary processes that existed hundreds of millions of years ago. We began our research by examining the 2.5 meters tall outcrop and collecting hand samples from every 0.25 meters. The rock samples were cut with a rock saw into 30 x 20 mm rectangular blocks that were polished and cut further into thin sections. The thin sections were analyzed for their lithologic and fossil content. The results of our study indicate that the outcrop varies from packstones to wackestones, changing from rocks that contain a high percentage of carbonate mud to an abundance of fossil constituents. Carbonate rocks such as limestones are formed in tropical marine environments and commonly capture a snapshot of the life that existed during that time. A shark tooth, genus petalodus, that lays atop the outcrop as well as microscopic organisms present in the rock such as, echinoderms, brachiopods, and gastropods disclose the fact that the there was a shallow marine environment present in this area when the rock was formed. The most significant finding was the identification of the foraminifera, Fusilinida, allowing us to assign a date of deposition of 323-252 million years old. This study has allowed us to reconstruct the paleoenvironment and understand Slippery Rock's geological past.