CHARACTERIZING SHIELD SPELEOTHEMS USING MOBILE LIDAR AT GRAND CAVERNS, GROTTOES, VA

Karst topography, especially underground features such as caves, are commonly found in the Shenandoah Valley. Grand Caverns (GC), located in the town of Grottoes, VA, is known to be the oldest show cave in the continental U.S. with continuous operations since 1806. GC is situated in the Conococheague Formation, characterized by overturned bedding, often perceived as unusual. Along with holding regional and relevant geological and historical heritages, GC also host a variety of shield speleothems (aka as cave shields). This research pursues the characterization and spatial distribution of shield speleothems at GC by using mobile lidar (Light Detection and Ranging) with SLAM (simultaneous localization and mapping) technology. In this ongoing study we are using a ZEB Horizon-GeoSLAM scanner with a capacity of 300 x 10³ pulses/s for the construction of high-resolution point cloud. During the first stage of this study, we constructed a comprehensive point cloud of 271.2 x 10⁶ points. Currently, we are examining 30 shield speleothems using the high-res point cloud and by conventional measurements (ground truth) to establish accuracy and precision of using a handheld lidar scanner. Preliminary results with conventional measurements show shield speleothems with an average size range of 180.3 cm in length (perpendicular to the axial growth), 174.5 cm in diameter, and a general orientation of 53.6°. Measured shields are in cave walls and observable from the current tour trail. This study could potentially enrich and fast track surveying work to describe speleothem density and diversity in caves.