Big slow-movers, debris slides and flows, and mega-boulders of the Blue Ridge Escarpment, western North Carolina, USA

Abstract

ABSTRACT This one-day field trip will explore the geomorphology, landslide mapping, geochronology, tectonics, meteorology, and geoengineering related to the Blue Ridge Escarpment (BRE), North Carolina, USA. Our aim is to show why it has persisted in the landscape and how it influences landslide frequency and the lives of the western North Carolina people. Some of the work we highlight has been published and some we present for the first time. Landslides pose a frequent geologic hazard to the people of western North Carolina, and they cause losses of road access, property, or, in the worst scenarios, human lives. We will also discuss landslide disaster response and mitigation efforts that required the collaboration of state and local emergency managers with other local, state, and federal agencies and the public. As we traverse the rugged terrain along the BRE in Polk and Rutherford counties, we will examine rockfalls, rockslides, debris flows, and debris slides occurring in late Proterozoic to early Paleozoic metasedimentary and meta-igneous rocks southeast of the Brevard fault zone. Our focus will be steep-walled, topographic reentrants where streams exploit brittle, post-orogenic bedrock structures, incise into the BRE, and produce landforms prone to debris flows and other types of mass wasting, often triggered by extreme rainfall events. The research we present on these extreme historical storms will help illustrate the scope and magnitude of the BRE’s influence on meteorological and hydrological events that lead to landslides and flooding. In addition to ongoing countywide landslide hazard mapping, a complementary research objective is to better understand the influence brittle cross-structures and earlier ductile bedrock structures have on rock slope failures and debris flows in the North Pacolet River valley and Hickory Nut Gorge, two major structurally controlled topographic lineaments.