INTEGRATING LEGACY DATA WITH NEW GEOLOGIC MAPPING TO CREATE A SEAMLESS GEOLOGIC MAP NEAR STATE COLLEGE, PENNSYLVANIA

Throughout time, the methodologies for creating new geologic maps have continuously evolved. As technology advances and our understanding of regional geology deepens, legacy data and their associated maps may appear inaccurate when compared to their modern counterparts. The Pennsylvania Geological Survey is currently pursuing the production of seamless compilation maps across Pennsylvania. While 1:24,000 scale legacy maps remain invaluable sources of geologic data, challenges arise when compiling them into these smaller scale maps. Consequently, addressing these inherent complexities became imperative. Here, we introduce one of our initial efforts aimed at assembling a seamless geologic map in order to correct cartographic, stratigraphic, and structural inconsistencies. This endeavor encompassed nine 7.5-minute quadrangles in central Pennsylvania including McAlevys Fort, Barrville, Burnham, Allensville, Belleville, Lewistown, Newton Hamilton, McCoysville, and McVeytown, all located within the Valley and Ridge Province. While eight of the nine quadrangles had previously been published by the Pennsylvania Geological Survey, the Burnham 7.5-minute quadrangle remained as a partially complete, unpublished draft. To seamlessly merge these quadrangles into a unified map, new mapping efforts were first undertaken to complete the Burnham quadrangle. Additionally, discontinuities between the previously published maps, colloquially termed “border busts” or “border faults,” were rectified via new mapping, review of historical field notes, and contact interpretation based on lidar-derived hillshade imagery. Given that the original maps were drawn atop topographic bases (apart from the McVeytown quadrangle), contacts within the quadrangles were also evaluated for conformation to topographical features using hillshade imagery derived from recently acquired lidar data. Moreover, elements of stratigraphic nomenclature were revised based on recent research conducted in Pennsylvania and neighboring states. The Pennsylvania Geological Survey aims to utilize these methodologies to continue creating seamless compilation maps throughout Pennsylvania.