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.
These data sets are not designed for use as a primary regulatory tool in permitting and siting decisions. This is public information and, as such, it may be used a reference source and may be interpreted by organizations, agencies, units of government, or others based on needs; however, each user is responsible for the appropriate application of the data. Federal, state, or local regulatory bodies are not to reassign to the Bureau of Topographic and Geologic Survey any authority for the decisions they make using these data sets.
The geologic units depicted on the published map are, in many cases, taken from source maps that were based on aerial photograph interpretation and limited, or no, field checking. Users are cautioned that, because of the nature and scale of the compilation and the source materials used, the geologic contacts, faults, and dikes may be off their true locations by several hundred feet locally. Users are also cautioned that, because the lithologies of many geologic units vary widely both laterally and vertically, the representation of the lithology of the geologic units based only on the dominant lithology (LITH1 in the polygon attribute table) is in many cases inappropriate, even at a regional scale.
The data sets are not meant for site-specific analysis or for use at finer (i.e., larger, more detailed) scales. Users are not to misrepresent the data sets by presenting them at scales for which they are not intended, nor to imply that presentation at such scales is approved by the PaGS.
The data sets are not to be redistributed for profit. Please refer to the section on Distribution_Liability for additional constraints.
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.
Attributes were reviewed by staff of the PaGS by (1) comparing check plots with the source maps; (2) visually checking attributes on a display of the map data on a computer workstation; (3) checking printouts of the attributes; and (4) running a macro to ensure correctness and consistency of polygon attributes. Based on these reviews, the attributes are believed to be accurate.
Because the data sets represent regional geology, some of the bedrock geologic units are (1) generalized, (2) combined with other units, or (3) slightly exaggerated in areal extent so that they may be represented at 1:250,000 scale (the scale of the 1980 map and the scale of accuracy of the data sets).
The faults and dikes are also generalized. As in the source maps from which they were digitized, the faults show offsets of map units as well as the regional structural grain, but they are not identified by name or by type (e.g., thrust, normal, or strike-slip).
The data sets do not include all of the information shown on the 1980 geologic map. For example, the data sets do not contain inset maps, marginal type, cross sections, and the base information, such as roads, streams, and political boundaries, shown on that map.
The lithologies in the polygon attribute table in the data set for geologic units and faults (items LITH1, LITH2, and LITH3) were modified from the geologic descriptions of the units in the map explanation of the 1980 map, based on reviews in 1998 and 2000 by PaGS staff geologists. The scope of the 1980 map did not include the mapping of lithologies, but rather the mapping of geologic formations which, in most cases, consist of more than one lithology. The lithologic designations in the explanation of the 1980 map are generalized and are not based on detailed field mapping or statistical analyses. Moreover, the lithologies of many geologic units vary considerably both laterally and vertically. Therefore, the dominant lithology (volumetrically) assigned to a given unit in the data set may constitute only a minor part of that unit in local areas. Additionally, the lithologies designated for each unit are generalized based on the areal extent of the unit within the entire state. In cases where a geologic unit contains members and other subunits that are present in only one region of the state, the lithologies for those subunits and members are applied to all polygons designated as that unit, regardless of the region in which the lithology occurs. For example, the Trimmers Rock Formation (Dtr) includes black shale of the Harrell Formation at its base in the Susquehanna Valley, so black shale is included as a lithology in the LITH3 category for all polygons in the state designated as Trimmers Rock Formation, even though the Harrell Formation is not present in the northeast.
The blackline mylar prints were scanned, converted to grids using ArcInfo software, and georeferenced. In an attempt to match as closely as possible the projection of the USGS 1- by 2-degree quadrangle maps that were used as the base for the 1980 map, the georeferenced grid was projected to transverse mercator using the following parameters: Projection: Transverse Units: meters Spheroid: Clarke1866 Parameters: 1.00000/*scale factor at central meridian -77 45 0.000/*longitude of central meridian 40 52 30.000/*latitude of origin 0.00000/*false easting (meters) 0.00000/*false northing (meters)
The scanned image was compared on screen with vector files for roads and streams imported from USGS standard 1:100,000-scale digital-line-graph (DLG) files. This comparison, as well as subsequent check plots, revealed that there were inherent problems and inconsistencies in the 1:250,000-scale base map used for the 1980 geologic map that made it difficult to obtain proper alignment of geologic contacts with streams and roads in the georeferenced digital data set. To obtain additional control, the source maps drawn by the compilers of the 1980 map were examined. These source maps contained the same geologic units shown on the 1980 map, but were drawn on paper 7.5- minute or 15-minute quadrangle base maps, many of which had been transcribed and published at page size in Berg and Dodge (1981). The page-sized 7.5-minute quadrangle maps were scanned, converted to grids, and georeferenced using the latitude and longitude at the four corners of each quadrangle for control. Following projection to transverse mercator, the roads and streams on the images of the page-sized source maps were compared on screen to the roads and streams from the USGS 1:100,000-scale DLG files. Most roads and streams from the DLG files fit those shown on the scanned images of the source maps to within 60 meters; thus, the page-sized source maps were considered to be good control for determining the placement of the geologic contacts at 1:250,000 scale.
Other source materials, including some containing updates and changes to the geology shown on the 1980 map, were similarly scanned and georeferenced (see credits.pdf for a list of sources scanned for each quadrangle).
The separate data set for dikes was prepared entirely by the PaGS using the scanned, georeferenced images from Berg and Dodge (1981) and other sources cited in credits.pdf. The arcs in the coverage were attributed with unit number, map symbol, name, age, and a lithology designation.
To conform to the regional scale of the compilation (1:250,000), tightly curved contacts on the source maps were generalized in the data set and units of small areal extent were exaggerated, but the generalization on the whole is less than that on the 1980 map. The degree of exaggeration that was employed by the compilers of the 1980 map in regard to the 1:250,000-scale base features (e.g., moving contacts away from roads and streams) was, in most places, ignored when contacts were digitized from the source maps.
Five attributes (UNITNO, AGE, LITH1, LITH2, and LITH3) were added to the polygon attribute table for geologic units and faults (pageo.pat), and the two polygon attributes (FM and NAME) that had been included in the USGS-WRD data set were redefined (MAP_SYMBOL and NAME). Six attributes (CONTACT, FAULT, BORDER, CONTACTLINE, FAULTLINE, and BORDERLINE) were added to the arc attribute table (pageo.aat), and the attribute values were assigned to the arcs as part of the editing process.
A script was prepared in Arc Macro Language (AML) to ensure correctness and consistency of polygon attributes. Using the script, the item "MAP_SYMBOL" was selected for each polygon, and the correct attributes for UNITNO, NAME, AGE, LITH1, LITH2, and LITH3 were calculated based on the map symbol.
After all corrections were made, the data sets were projected to new data sets in a geographic coordinate system (units in decimal degrees). The latter data sets were exported as ArcInfo export files (pageo.e00 and padike.e00) and were converted to polygon and arc shapefiles (pagpoly.shp, pagarc.shp, padike.shp) using ArcView software.
In the data set for geologic units and faults, the entity type is a geologic unit as shown on
the 1980 state geologic map (Berg and others, 1980). Each geologic unit consists of a
sequence, group, formation, or member. The units are distinguished from each other by
geologic characteristics such as rock type, color, and texture, and are mappable at the scale
of 1:250,000. Units shown on the 1980 map are intended to be rock-stratigraphic (i.e.,
correlations shown or implied are rock correlations and may transgress time boundaries).
The polygon and line (arc) attribute items for the entity type of geologic unit are in
typical ArcInfo feature class format. Polygon attribute items (in table pageo.pat) are
as follows:
COLUMN ITEM NAME WIDTH OUTPUT TYPE N. DEC. INDEXED?
1 AREA 8 18 F 5 --
9 PERIMETER 8 18 F 5 --
17 PAGEO# 4 5 B -- --
21 PAGEO-ID 4 5 B -- --
25 UNITNO 4 4 I -- --
29 MAP_SYMBOL 10 10 C -- --
39 NAME 100 100 C -- --
139 AGE 50 50 C -- --
189 LITH1 35 35 C -- --
224 LITH2 35 35 C -- --
259 LITH3 85 85 C -- --
Please note that the shapefile for polygons (pagpoly.shp) has the same items, but the "#"
symbol is changed to "_" in the conversion from the ArcInfo file.
Definitions of user-defined polygon attribute labels are as follows. Please refer to
polyattrib.pdf for a complete list of attribute domain values for each item, and to
changes.pdf for a list of changes and updates made in the data sets to map symbols,
names, and ages from those shown on the 1980 state geologic map (Berg and others,
1980).
UNITNO: A unique number assigned to each map unit in the data set. The number,
which is not derived from the 1980 map, places the units approximately, but not
completely, in a sequence ranging from those having the youngest ages (lower
numbers) to those having the oldest ages (higher numbers). In the data set for geologic
units and faults, there are 193 unique unit numbers ranging from 1 to 195 (unit number
6, kimberlite, and unit number 15, Quarryville Diabase, occur only in the data set for
dikes).
MAP_SYMBOL: The symbol used to label the unit on the 1980 state geologic map,
except where modified as indicated in changes.pdf. Please note that the "double-bar
P" shown on the 1980 map to indicate units of Pennsylvanian age has been changed
to "P," the special character for Triassic units (capital "T" joined to small capital "R")
has been changed to "Tr,"and the special character for units of Cambrian age ("C"
with horizontal bar) has been changed to "C" in the attribute table.
NAME: The name of the geologic unit in the explanation of the 1980 state geologic
map (Berg and others, 1980), except where modified as indicated in changes.pdf.
AGE: The age of the geologic unit as shown on the 1980 state geologic map (Berg and
others, 1980), except where modified as indicated in changes.pdf. Ages are at the level
of a geologic period.
LITH1: The dominant lithology, volumetrically, in the rock unit. Lithologies were
modified from the geologic description in the map explanation of the 1980 state
geologic map (Berg and others, 1980), based on reviews by PaGS staff geologists in
1998 and 2000. The lithologies are assigned based on the entire areal extent of the
geologic unit within Pennsylvania; thus, all lithologies listed (particularly in the
LITH3 item) may not be present in local areas.
LITH2: The secondmost dominant lithology, volumetrically, in the map unit. See
LITH1 above for source.
LITH3: Other major lithologies, volumetrically, in the rock unit. See LITH1 above
for source.
The arc attribute items (in table pageo.aat) are as follows:
COLUMN ITEM NAME WIDTH OUTPUT TYPE N. DEC. INDEXED?
1 FNODE# 4 5 B -- --
5 TNODE# 4 5 B -- --
9 LPOLY# 4 5 B -- --
13 RPOLY# 4 5 B -- --
17 LENGTH 8 18 F 5 --
25 PAGEO# 4 5 B -- --
29 PAGEO-ID 4 5 B -- --
33 CONTACT 5 5 C -- --
38 FAULT 5 5 C -- --
43 BORDER 5 5 C -- --
48 CONTACTLINE 30 30 C -- --
78 FAULTLINE 30 30 C -- --
108 BORDERLINE 15 15 C -- --
Please note that the shapefile for arcs (pagarc.shp) has the same items, but the "#" symbol
is changed to "_" and "CONTACTLINE" has been truncated to "CONTACTLIN" in the
conversion from the ArcInfo file.
Definitions of user-defined arc attribute labels and attribute domain values are as follows:
CONTACT: Indicates whether the line is a contact (y, yes; n, no).
FAULT: Indicates whether the line is a fault (y, yes; n, no).
BORDER: Indicates whether the line forms the border of the data set (y, yes; n, no).
CONTACTLINE: The type of contact line between geologic units shown on the 1980
state geologic map. The types of contact lines (i.e., the attribute values) in the data set
for geologic units are as follows:
Solid: A contact line between two geologic units that is shown as a solid line on the
1980 map. Quantitative locational accuracy values are not known.
Dashed: A contact line between two geologic units that is shown as a dashed line on
the 1980 map. The location of a dashed contact line is more approximate than that
of a solid contact line. Quantitative locational accuracy values are not known.
Arbitrary: A contact line between geologic units that is shown as a color break only
(i.e., no line is shown) on the 1980 map. This type of contact typically occurs where
two or more geologic units are mapped separately on one side of the contact line and
are grouped together as one unit on the other side of the contact line. The units are
grouped either because (1) their individual unit areas are too small to be shown at the
scale of 1:250,000; or (2) the geology of the area has not been mapped in sufficient
detail to allow the units to be distinguished separately. An arbitrary contact line may
also represent a facies change (i.e., a lateral variation between sedimentary rocks that
were deposited during the same time period but in different sedimentary
environments). In such cases, the approximate area of the change from one unit to the
other is indicated by the arbitrary line. An arbitrary contact line is also used to bound
the Valentine Member of the Benner Formation, which is generalized on the 1980
map as a line of uniform width, and which is included in the data set as a polygon of
uniform width.
Queried: A contact line between two geologic units that is shown as a queried line
on the 1980 map or source materials used for that map. A queried line indicates that
the location of the contact is uncertain or questionable.
FAULTLINE: The type of fault line shown on the 1980 state geologic map. The types
of fault lines (i.e., attribute values) in the data set are as follows:
Solid: A fault line that is shown as a solid line on the 1980 map. Quantitative
locational accuracy values are not known.
Dashed: A fault line that is shown as a dashed line on the 1980 map. The location
of a dashed fault line is more approximate than that of a solid fault line. Quantitative
locational accuracy values are not known.
Queried: A fault line that is shown as a queried line on the 1980 map or source
materials used for that map. A queried line indicates uncertainty about the
existence of the fault.
BORDERLINE: A term used to define the type of line that generally forms the outer
boundary of the data set. The types of border lines (i.e., attribute values) in the data
set are as follows:
State: The Pennsylvania state boundary.
Quad: The boundary of a 30-by 60-minute quadrangle within Pennsylvania.
Lake Erie: The shoreline of Lake Erie.
In the data set for dikes, the entity type is a dike as shown on the 1980 state geologic map
(Berg and others, 1980). Although dikes are tabular features, because of the scale, they are
shown as lines on the 1980 map and have been digitized as lines (arcs) in the data set. The
arc attribute items (in table padike.aat) are as follows:
COLUMN ITEM NAME WIDTH OUTPUT TYPE N. DEC. INDEXED?
1 FNODE# 4 5 B -- --
5 TNODE# 4 5 B -- --
9 LPOLY# 4 5 B -- --
13 RPOLY# 4 5 B -- --
17 LENGTH 8 18 F 5 --
25 PADIKE# 4 5 B -- --
29 PADIKE-ID 4 5 B -- --
33 UNITNO 4 4 I -- --
37 MAP_SYMBOL 10 10 C -- --
47 NAME 100 100 C -- --
147 AGE 50 50 C -- --
197 DIKELINE 15 15 C -- --
212 LITH1 35 35 C -- --
Please note that the shapefile for arcs (padike.shp) has the same items, but the "#"
symbol is changed to "_" in the conversion from the ArcInfo file.
Definitions of user-defined dike attribute labels are as follows. Please refer to
dikeattrib.pdf for a complete list of attribute domain values for each item, and to
changes.pdf for a list of changes and updates made in the data sets to map symbols, names,
and ages from those shown on the 1980 state geologic map (Berg and others, 1980).
UNITNO: See definition of "UNITNO" in polygon attributes for the data set for
geologic units and faults above.
MAP_SYMBOL: The symbol used to label the dike on the 1980 state geologic map
(Berg and others, 1980), except where modified as indicated in changes.pdf.
NAME: The name of the geologic unit in the explanation of the 1980 state geologic
map (Berg and others, 1980), except where modified as indicated in changes.pdf.
AGE: The age of the geologic unit as shown on the 1980 state geologic map (Berg and
others, 1980), except where modified as indicated in changes.pdf.
DIKELINE: The type of line symbol used for the dike on the 1980 state geologic map.
The types of dike lines (i.e., attribute values) in the data set are as follows:
Solid: A dike line that is shown as a solid line on the 1980 map. Quantitative
locational accuracy values are not known.
Dashed: A dike line that is shown as a dashed line on the 1980 map. The location
of a dashed dike line is more approximate than that of a solid dike line. Quantitative
locational accuracy values are not known.
LITH1: The dominant lithology, volumetrically, in the rock unit. See source for
lithologies in definition of "LITH1" in the polygon attributes for the data set for
geologic units and faults above.
The Commonwealth of Pennsylvania makes no guarantee or warranty concerning the accuracy of information contained in the geographic data or accompanying documentation. The Commonwealth of Pennsylvania further makes no warrantees, either expressed or implied, as to any other matter whatsoever, including, without limitation, the completeness or condition of the product, or its fitness for any particular purpose. The burden for determining fitness for use lies entirely with the user.
Although these data have been processed successfully on a computer system at the Bureau of Topographic and Geologic Survey, the Commonwealth of Pennsylvania makes no warranty, expressed or implied, regarding the use of the data files or accompanying documentation on any other computer system, nor does the act of distribution constitute any such warranty.
The user shall save the Commonwealth of Pennsylvania harmless from any suits, claims, or actions arising out of the use of or any defect in the data files or accompanying documentation.
The Commonwealth of Pennsylvania assumes no legal liability for the accuracy, completeness, or usefulness of the data files and accompanying documentation. In no event shall the Commonwealth of Pennsylvania have any liability whatsoever for payment of any consequential, incidental, indirect, special, or tort damages of any kind, including, but not limited to, any loss of profits arising out of use of or reliance on the geographic data.
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