A NEW DIGITAL GEOLOGIC MAP OF THE BLUE RIDGE PARKWAY IN NORTH CAROLINA

The North Carolina Geological Survey (NCGS) in collaboration with the National Park Service (NPS) Geologic Resources Division and Inventory and Monitoring Program is mapping the bedrock geology and geologic hazards of the Blue Ridge Parkway (BRP) in North Carolina. This interim map presents the progress the NCGS has made to date and covers most of the roadway from Blowing Rock, NC to its southern terminus in Cherokee, NC (mileposts 292 to 459). The map is being produced in a digital format that will facilitate distribution of data to NPS field personnel.

Numerous data layers comprise the bedrock geologic map including: (1) regional map units (depicted on 1:250,000 scale maps), (2) map units typically mapped on detailed 1:24,000 scale maps and larger, (3) outcrop control map that shows the various rock types at each station, (4) seven categories of structural features, (5) rock descriptions including thin section and whole-rock analyses, (6) geologic cross sections of selected areas, (7) correlation diagram, and (8) explanation of geologic map symbols.

The NCGS collects data at almost every outcrop along the roadway. This level of detail allows bedrock geology to be mapped and utilized at 1:12,000 or larger scale. Information is recorded using an integrated GPS/GIS data collection system. This method creates a digital outcrop control map in real time and drastically speeds up map unit compilation. One advantage this format has over traditional paper geologic maps is that it allows NPS personnel in the field to view specific data for each individual station and not just broad map units. This information is significant for studies of the soil, vegetation, and animal life of a small area and allows future workers to “know what the geologist was seeing.”

The geologic hazards map includes: (1) location and classification of slope movements and slope movement deposits (recent and old), (2) potential slope movement areas, and (3) slope stability assessment data collected at existing or potential slope movement locations. Many of the geologic hazard stations have associated digital media files. These files contain a wealth of information, including pictures, describing the geology, structural features (including kinematic rock slope stability analyses using stereonets), and hazards present at a given location.