produced by the United States Geological Survey in cooperation with Pennsylvania Department of Conservation and Natural Resources, Bureau of Topographic and Geologic Survey
produced by the United States Geological Survey in cooperation with Pennsylvania Department of Conservation and Natural Resources, Bureau of Topographic and Geologic Survey
produced by the United States Geological Survey ; state of Ohio, Department of Transportation, Department of Natural Resources, Division of Geological Survey
produced by the United States Geological Survey in cooperation with the North Carolina Department of Environment and Natural Resources ; North Carolina Geological Survey