SUBTERRANEAN, SURFACE, AND LIDAR-DERIVED BEDDING ORIENTATIONS REFINE THE STRUCTURAL FEATURES IN THE BURNSVILLE COVE, BATH AND HIGHLAND COUNTIES, VIRGINIA

The Burnsville Cove, located in the Burnsville and Williamsville 7.5” quadrangles in the Valley and Ridge Province in west-central Virginia, is underlain by Silurian to Devonian carbonates, shales, and minor sandstones. Geologic mapping has been hampered by inaccurate base maps and typically limited exposures in carbonate and shale valleys. Fortuitously, over 100 caves within the Burnsville Cove provide nearly continuous outcrop. A three-pronged approach of subterranean structural measurements, traditional field work, and Lidar-derived measurements help to clarify structural features and increase the accuracy of the geologic map.

The Burnsville Cove caves contain over 116 kilometers (72 miles) of surveyed passages. In the otherwise outcrop-poor carbonate valley, the caves provide numerous bedrock exposures and show secondary folding and minor thrust faulting. In-cave bedding orientation measurements demonstrate that the Sinking Creek Syncline is broad, flat bottomed, and located slightly off from where published maps indicated. The structure of the adjacent Chestnut Ridge Anticline is not as straightforward as previously believed. Field work demonstrates the Wills Creek Formation is exposed at the crest of the Chestnut Ridge Anticline and provides additional datapoints for the geologic map. Newly available Lidar digital elevation models (DEMs) provide a more accurate base map. The DEMs facilitate extraction of structural measurements without the field work and reveal additional structural features.

Collection and interpretation of this data leads to revisions of the geologic map showing more complex structures than previously documented. It is also a reminder of the structural variability in the Valley and Ridge province of Virginia.