This file was generated as part of a batch of 349 shapefiles that were deemed to be of interest for conversion to GIS format. 188 figures/maps are represented by these shapefiles. Source data for the batch conversion project were in one of three types: 1) georeferenced digital ASCII files previously converted into shapefile format; 2) non-georeferenced, graphics format (.wmf); and 3) paper maps. Type 1 shapefile data were checked for completeness of line and polygon features, edited, then attributed with the figure title and individual feature descriptions given in the map legends. Type 2 data followed the same workflow as Type 1, except that the figures were first converted to DXF format then transformed using ArcInfo into real-world coordinates. The relatively few maps of Type 3 were scanned into image format, digitized in heads-up mode, then handled the same as Type 2 data. A quality-checking system was used to track the status of each figure and file as the work proceeded. Check plots of each map at the respective source map scale and projection and were compared to originals by the supervising geologist (M. Grobe). Errors were flagged and subsequently corrected. Once the data had been thoroughly checked, the shapefiles were projected into geographic coordinates, NAD 83 datum.

ArcMap layer files were created to render the shapefile data as they appear in the Geological Atlas. This step served to further the quality control for the data. Minor edits were required to about 10 shapefiles in order to symbolize them as they appear in the Atlas.