A NEW MULTILAYERED GEOLOGIC BEDROCK ARCGIS ONLINE WEB MAP OF WESTERN NORTH CAROLINA

In an effort to make bedrock geologic maps more readily available to the general public the Asheville Regional Office of the North Carolina Geological Survey (NCGS) has created an ArcGIS Web Map for western North Carolina (WNC). The current Geo App consists of 28 7.5-minute quadrangle maps combined in a single ArcGIS layer. All of these maps were produced in cooperation with the National Cooperative Geologic Mapping Act, STATEMAP component. This layer will serve as a starting point, with additional quadrangles being appended as they are formatted and edge matched to existing mapping. Of 228 7.5-minute quadrangles in WNC, 85 have been mapped in detail (1:24,000-scale), 53 have moderate geologic control, and 90 have only a reconnaissance level of coverage. The eventual goal of the Web Map is to cover all of WNC at a 1:24,000 scale.

Current functionality allows users to view three scale-dependent layers: 1) terrane map; 2) metamorphic suite/formation map; or 3) detailed 1:24,000-scale geologic map depicting units, sub-units, and members.

Detailed bedrock units are represented by polygons with associated data including: terrane name, formation name, lithologic unit name, geologic age, unit label, unit description, and available geochronology. These data are easily accessed from within the Web Map by clicking on the polygon of interest. A symbolized polyline layer representing bedrock contacts accompanies the bedrock layer. All data are Federal Geographic Data Committee (FGDC) compliant.

Challenges to completion of the digital map include reconciling formation/unit names and stratigraphic relationships, as well as quadrangle boundary contact differences caused by the varying interpretations of different map authors, often working decades apart. Additional fieldwork will be required to resolve many of these differences. Future versions are planned that will hopefully allow users to search outcrop-specific details, photographs, and structural measurements.