Description: Two digital data sets, one for geologic units and faults and the other for dikes, have been prepared for Pennsylvania. The data sets were digitized primarily from the artwork used for the 1980 "Geologic Map of Pennsylvania" (Berg, T. M., Edmunds, W. E., Geyer, A. R., and others, compilers, 1980, Geologic map of Pennsylvania: Pennsylvania Geological Survey, 4th ser., Map 1, scale 1:250,000) and from source materials used for that map. Many of the source materials had been published as page-sized maps and were digitized from this published paper copy (Berg, T. M., and Dodge, C. M., 1981, Atlas of preliminary geologic quadrangle maps of Pennsylvania: Pennsylvania Geological Survey, 4th ser., Map 61, scale approx. 1:62,500). The other source materials consist of unpublished and published maps at various scales. It was beyond the scope of the project to incorporate revisions that had been made to the geologic units since the 1980 map was compiled; however, some updates to formational contacts, faults, and dikes, as well as to geologic nomenclature and ages, were incorporated where the revisions could be easily made. The 1980 Pennsylvania state geologic map (Berg and others, 1980) shows the areal distribution of 194 bedrock geologic units. The units range in geologic age from Quaternary to Precambrian and encompass a wide variety of lithologies. The map was compiled and published in a transverse mercator projection at 1:250,000 scale. The two digital data sets include 195 geologic units, which, for the most part, closely correspond to those shown on the 1980 map. The data sets were prepared using ArcInfo software and are provided in a geographic coordinate system (units in decimal degrees). Although it is possible to portray digital data at any scale, the geologic formational contacts, faults, and dikes represented in these data sets are not intended to be used at any scale finer than 1:250,000.The polygon attributes in the data set for geologic contacts and faults include unit number, map symbol, name, age, and three lithology categories that represent the general lithologic makeup of each geologic unit. Each arc (line) in the data set is attributed as one or more of the three general categories of contact, fault, or border. Contact lines are attributed according to the type of contact shown on the 1980 map (solid, dashed, queried, or arbitrary). Fault lines are similarly attributed (solid, dashed, or queried). Borders are attributed as either state boundaries, quadrangle boundaries, or the shoreline of Lake Erie. The data set for dikes consists of arcs attributed with unit number, map symbol, name, age, lithology, and type of dike (solid or dashed).It is anticipated that the digital data sets will be used for a variety of regional or statewide geographic-information-system applications, including water-resource and environmental studies, conservation and ecosystem management, mineral exploration, and regional land use planning and development.
Copyright Text: Geologic contacts, faults, and dikes are primarily from Berg and others (1980) and Berg
and Dodge (1981); however, several other sources were also used, which cannot be
efficiently documented in this format. Users are referred to credits.pdf for a list, by 7.5-
minute quadrangle, of sources of geologic maps used to prepare the data sets and
credits for the geologic work; to references.pdf for complete bibliographic citations for
the sources; and to changes.pdf for an explanation of the global revisions that were
made to the geologic units, ages, and nomenclature from those shown on the 1980
map.
Lithology designations are modified from Berg and others (1980), based on reviews
by Rodger T. Faill and other staff geologists of the Bureau of Topographic and Geologic
Survey (PaGS) in 1998 and 2000.
Data sets of geologic units prepared from the 1980 map in the late 1980's and early 1990's
by the U.S. Geological Survey, Water Resources Division, were initially used by the PaGS
but were extensively revised and, in many places, completely redigitized during the course
of the project.
The assistance of Robert C. Smith, II, and Rodger T. Faill, both of the PaGS, in resolving
several geologic questions and problems that arose during the digital work is acknowledged
with appreciation.
Specific digital work (scanning, georeferencing, digitizing, attributing, and proofing) is
documented by 7.5-minute quadrangle in credits.pdf. General digital work (i.e., not
specific to quadrangles) is as follows. Elizabeth M. Stone, Jason M. Taylor, and
Rebecca A. Fox (student interns) assisted with general scanning, georeferencing, and
digitizing tasks in the early part of the project. Color tables for the map units in the
data set were prepared by Thomas G. Whitfield, Elizabeth M. Stone, and Christine E.
Miles. Annotation (labeling) of the map units was done by John G. Kuchinski. Most
final proofing of the data sets was by Christine E. Miles, with some assistance by
Thomas G. Whitfield and Darren A. Szuch (student intern). Macros for polygons
were prepared by Christine E, Miles and Thomas G. Whitfield, with assistance from
Jason M. Taylor, Erika M. Ballerstein, and Darren A Szuch (student interns); macros
for arcs were prepared by Christine E. Miles. Metadata (this document) and some
accompanying files (changes.pdf and polyattrib.pdf) are by Christine E. Miles. Credits
and the associated reference list (credits.pdf, and references.pdf) are by Christine E.
Miles and Thomas G. Whitfield. The map explanation (explanation.pdf) was compiled
by Christine E. Miles. Web data files ad descriptions were prepared by Christine E. Miles.
Description: This point dataset represents an (incomplete) inventory of karst features (herein categorized as sinkholes, surface depressions, surface mines, or cave entrances) that have been cataloged in Pennsylvania by the staff of the Pennsylvania Geological Survey since 1985. County-wide karst-feature inventories for fourteen counties (Adams, Berks, Bucks, Centre, Chester, Cumberland, Dauphin, Franklin, Lancaster, Lebanon, Lehigh, Montgomery, Northampton, and York) were originally released as hard-copy open file reports by the agency. The user of this dataset would be well served to consult one of those reports for specifics on how the inventories were conducted. Data are also provided from incidental reports of karst features as well as partial or cursory inventories in eight additional counties (Bedford, Blair, Clinton, Fulton, Huntingdon, Juniata, Lycoming, and Mifflin). The majority of these features were identified on contact prints of USDA, USGS, and other aerial photography. Photo locations were then transferred to paper copies of USGS 7.5 minute quadrangles where the coordinates for the locations were determined using a constantly evolving array of technologies from mylar overlay grids, through early proprietary mapping software and more recently with GIS and GPS technology. . Some features in urbanized areas were identified via questionaires that were sent to the municipalities in the counties being inventoried. The locations of surface mines and cave entrances were garnered from historical geological publicatons. Locations of historical iron mines and other activities often associated with karst features were garnered from historical geological publications. Field surveys were undertaken to establish protocol for future mapping efforts as well as to verify the field presence of interpreted features. Field verified sites are not identified in the data set. Karst features change considerablely over time. Sinkholes become filled or subsidence is repaired. One of the motivations for the karst inventory program was the rapid development taking place in many of the counties where karst could be a problem. Development obliterates much of the evidence for underlying karst features.