16-17 Investigating the Harlansburg Cave

Session: From Thin Section to Outcrop: Exploration of Undergraduate Research (Posters)

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Abstract:

The Harlansburg Cave is located in western Pennsylvania and is incised into the Vanport Limestone below the Kittanning Sandstone that are a part of the Allegheny Group from the middle Pennsylvanian period (~314 – 306Ma). The cave was discovered during a road cutting project in 1950 for PA Route 108 and is a maze cave containing numerous closed loops of interconnected passages. The cave is currently being mapped by the Pennsylvania Geological Survey. Folded sedimentary rocks throughout the broader Appalachian region indicate the presence of ridges and valleys, and similar structures may be observable within Harlansburg Cave. We are conducting a lithofacies analysis of the cave’s rocks to determine their depositional environments. Hand samples will be collected from along the roadcut outcrop leading to the cave, then prepared into thin sections for petrographic analysis. We have also begun to describe the fossil assemblage of the cave, which represents a shallow marine environment, based on the presence of crinoids present in the Vanport Limestone and a fluvial and deltaic system of the Kittanning Sandstone based on the presence of Lycopod and Lepidodendron fossils. We are measuring exposed fossils in situ using calipers and a tape measure to provide quantitative information on the size distribution of the invertebrate community. Finally, we are generating a 3D model of a portion of the cave using a handheld LiDAR device. This method records point cloud data that will be processed to create a model that will provide valuable information on the geometry of the cave system. This model will be made available to the public/Mid-Atlantic Karst Conservancy/whoever will have access. The 3D model will allow us to examine the cave’s geometry so that we can determine dissolution rate and begin to investigate how the cave formed. While the cave is infiltrated by meteoric waters, the cave may been initially formed from fluctuating groundwater levels. This project will allow us to better understand where other unknown cave systems exist as well as build upon the greater knowledge of cave formation geometry and the processes that create these different structures.

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