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Paper No. 62-7
Presentation Time: 2:00 PM-6:00 PM
INSIGHT INTO CAVE DEVELOPMENT THROUGH SOIL ANALYSIS AT OWL CAVE, HIGHLAND COUNTY, VIRGINIA
Mobile sediments in karst regions can have a profound influence on sediment transport within cave systems. Variation in the sediments inside a cave can provide insight for water flow during various stages of cave development. Few studies have characterized internal cave sediments, despite the recorded variability during development that remains largely protected from the local climate. A previous study observed a decrease in organic carbon contents from the entrance to dark internal chambers in the submarine Trémies cave system near Marseille, France. This current study compared the particle size distribution and organic carbon contents of two samples collected from Owl cave in Highland County, Virginia. Two sediment cores were obtained, one from inside the cave and the other from the cave entrance. Particle size distribution was preformed prior to and after removal of organic carbon using laser diffraction methods. The loss on ignition method was used (550 0C for 2 hours) to remove and determine the percentage of organic carbon. Pooled T-test compared the variability of particle sizes and organic carbon of the two cores. Even after the removal of organic carbon, the inside samples showed significantly higher sand content than the entrance. Silt content in the cave entrance samples were significantly greater than inside, while the variation in clay content was not significant. The percentage of organic carbon inside the cave was below 5% while the entrance samples decreased from ~7% at the surface to5% in the sub-surface. Burning of organic carbon resulted in greater variability of particle sizes for both cores. The difference in particle sizes inside and outside of the cave are attributed to influx of sediments only during high intensity flow regimes and weathering of the cave walls. The difference between the silt contents indicates water flux in the cave rarely stagnated and the flow aided in cave development after the initial passages formed.