INVESTIGATING SEDIMENT DEPOSITION PROCESSES IN CAVE ECOSYSTEMS THROUGH PHYSICAL AND GEOCHEMICAL PROPERTIES

Understanding the interplay of sedimentation processes is essential to reconstructing past environments and environmental conditions and assessing ongoing ecological dynamics within cave systems. In this research, we aimed to explore the physical and geochemical properties of sediments inside Water Sinks Cave in Highland County, Virginia to reconstruct the history of these sediments and, by extension, the cave itself, focusing on whether the sediment accumulation is autochthonous or allochthonous. We collected thirty-seven sediment samples from an unstudied sediment pile in one of the upper passageways of the cave, and analyzed sediment particle size, soil organic carbon, and chemical composition. Additionally, we collected samples from five sites outside the cave for comparative analysis. Our particle size analysis revealed that most inside samples were predominately silt, with smaller amounts of clay and sand; although, variations with higher sand and lower silt content were observed at shallower depths. Outside samples were also mostly silt but had higher sand concentrations. Soil organic carbon analysis showed a slight increase in carbon levels with depth inside the cave, while outside samples exhibited decreasing carbon levels with depth. Water content in both the inside and outside samples tend to increase with depth. These findings suggest that the Water Sinks sediment pile may have resulted from multiple sediment influx periods, as indicated by similarities in particle size between the inside and outside sample groups. The soil organic carbon content of the deeper sediments within the cave supports the hypothesis that older sediments originated from outside the cave, while younger sediments may represent in situ deposits. Going forward with this project, we hope to continue work on elemental and mineral analysis as well as age dating our sediments.