HISTORICALLY DESTRUCTIVE LANDSLIDES OF THE HICKORY NUT GORGE NEAR CHIMNEY ROCK, NORTH CAROLINA

Historical accounts of landslides induced by major storm events (1916, 1996) along Hickory Nut Gorge near Chimney Rock, NC as well as a rockfall (2012) along massive exfoliating cliff faces, and the empirical evidence of enormous boulders scattered throughout the valley show that this region is prone to slide. Also, an earthquake swarm starting in 1874 and stories of Rumbling Bald Mountain hint at a possible seismic influence on land sliding near Chimney Rock. We have used aerial imagery, contour/elevation data derived from LIDAR, and field work to develop a map to display the spatial distribution and types of landslide deposits to uncover the main contributing factors which cause the landslides in the Hickory Nut Gorge. Preliminary results reveal that the most common landslide types are rock fall, debris avalanche, and debris flow. Our preliminary interpretation, based on the storm events which triggered multiple landslides in the past century, suggests that precipitation is the key cause of landslides in the area. Proximal to the Rocky Broad River, historical events typically discharged debris along incised channels directly to the river’s floodplain where large boulders accumulate. The tributary channels are incised across narrow strips of younger terraces and extensive older debris flows. Geomorphic form and the heights above terrace levels suggests that landslide processes (e.g., debris avalanches) have dominated erosion and deposition within the lower slopes of the river valley with fluvial processes gradually removing finer material along the floodplain. In an area with so much tourism due to Chimney Rock State Park and Lake Lure, it is imperative to gain a better understanding of the landslides which pose a threat to the public here.