32 Hydrogeology

Added due to amount of discipline abstracts submitted.

Tuesday, 10 March 2026
1:30 PM - 5:30 PM
RCC, 106

Investigating the Sediment Accumulation Dynamics at the Water Sinks Cave, Highland County Virginia

Paper number: 32-4
Program: Technical Sessions
Time: 2:30 PM – 2:45 PM

Authors

Abstract

Clastic cave sediments can be either autochthonous (autogenic) or allochthonous (allogenic). Understanding the deposition process of these sediments is crucial for reconstructing the paleoenvironmental conditions. The Water Sinks depression is one of the largest closed depressions at the northeastern end of Burnsville Cove in Highland County, Virginia. The depression acts as the final sink for several streams originating from the Jack Mountain and Chestnut Ridge. Prior to 2007, there were two modest-sized caves in the depression, Owl Cave and Water Sinks Cave. In November 2007, a large lower level of the Water Sinks Cave was discovered. This relatively recently discovered level of the cave consists of a series of upper-level passages with both flowstone and sediment banks nearly 25 feet tall. In 2023, we collected 37 sediment samples from the sediment pile at different depths to determine its origin by physically and chemically characterizing the sediments. We hypothesized that the sediment pile has an allogenic origin, as depressions serve as the final sinking points for many streams. Additionally, a handheld 3D LiDAR scanner (GeoSLAM) was used to develop a 3D model of the cave. A drone-based LiDAR scanner (Zenmuse L2 Scanner) was used to obtain a high-resolution aerial point cloud, which was used to develop a DEM to visualize the stream network around the cave, ultimately aiding in identifying sediment transport pathways. Sediment sample analysis revealed higher sand content in the upper layers and lower silt concentrations at shallower depths. Similarly, exterior samples (Cave outside) were primarily silt but exhibited higher sand content. These findings suggest that the cave’s sediment pile is likely formed from multiple influx episodes, as indicated by particle size similarities between interior and exterior sediments. The increase in organic carbon in deeper cave sediments supports the hypothesis that older deposits are externally sourced, while younger sediments may represent in situ deposits. Nevertheless, X-ray diffraction (XRD) analysis of the samples indicates that quartz is the dominant mineral, followed by orthoclase feldspar. The mineralogy suggests that chert, derived from a limestone matrix, is the primary sediment source, implying an autochthonous origin instead. These findings challenge the original hypothesis of an allochthonous source, even though the depression serves as the final sink for many streams originating within the cave system.  

Geological Society of America Abstracts with Programs. Vol. 58, No. 1

doi: 10.1130/abs/2026SE-411885

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