In the mid1980s, Art Schultz (USGS, ret.) drew on experiences in the Colorado Front Range to identify numerous large, stratigraphically intact, kilometerscale bedrock landslides on interbedded sandstoneshale dip slopes in the Virginia Valley and Ridge. The physical scale of the slides, along with the thick forest cover, made slide identification challenging, as slides could easily be mistaken for compressional foldthrust features detached in shale horizons. As a result, the distribution and extent of blocksliding could not be fully evaluated at the time. Revisiting Valley and Ridge slopes with newly available 1meter lidar datasets highlights the ubiquity of dip slope failure in the central and southern Appalachian Valley and Ridge, with many slides showing morphological features that imply relative youth. In addition to translational blockslides, lidarderived imagery reveals numerous sackungen in rugged topography developed on gently dipping, interbedded sandstoneshale ridges. Abandoned late 19th and early 20th century iron mines on intact slopes in the vicinity of large blockslides show deepseated slope movement almost certainly related to mine excavations. The extent of these movements relative to excavation size suggests that caprocksupported rugged topography in the Valley and Ridge may exist at or near the mechanical limit of weaker strata interbedded within the caprock interval. Lidarsupported investigation of Valley and Ridge bedrock slope movements invites reflection on the interpretive skill of Schultz and collaborators and a reconsideration of how potential slope behavior may impact infrastructure in the region.”

Prince (2023) Blockslides, summit grabens, and collapsing highwalls of the Appalachian Valley and Ridge: Using lidarderived imagery to reevaluate a thoroughly studied landscape, USGS Landslide Hazards Seminar, 18 January 2023.

USGS Video: https://cms.usgs.gov/media/videos/blo...