"This report provides a statewide statistical summary of the hydrogeologic, water-chemistry, and well-construction characteristics of the stratigraphic units on the 1980 edition of the Pennsylvania state geologic map (T. M. Berg and others, compilers, 1980, Geologic map of Pennsylvania, Pennsylvania Geological Survey Map 1, scale 1:250,000). ... Statistics may be sorted by stratigraphic unit, physiographic section, topographic position, and water use, or any combination of these criteria--Introduction.