USGS Geoscience Data Catalog

Title:

Areal Extent of the Pittsburgh Coal Bed and Horizon and Mined Areas of the Pittsburgh Coal Bed

Abstract:

This dataset is an polygon coverage of the Pittsburgh Coal bed and Horizon. The polygons are subdivided into areas where resources are unknown, areas where resources are known but not yet mined, and areas where resources are known and are mined.
Introduction:
This map is one of many Geographic Information System (GIS) products of the National Coal Assessment that is being conducted by the U.S. Geological Survey in cooperation with State gological surveys and other Federal and State agencies. The base of the Pittsburgh Coal bed and its equivalent horizon is used to subdivide Upper Pennsylvanian Series strata into the overlying Monongahela Group and the underlying Conemaugh Group in the Appalachian Basin. This map depicts the Pittsburgh Coal bed and stratigraphically-equivalent non-coal strata, herein referred to as the Pittsburgh Coal bed and horizon.
The Pittsburgh Coal bed and horizon occurs in eastern Ohio, central and northern West Virginia, western Pennsylvania, and western Maryland. This map, consisting of the original-extent GIS layer and the mined-area layer, will be combined with coal isopach and coal bed structure layers for calculating remaining coal resources.
On this map, four types of information are shown: (1) original extent of the Pittsburgh Coal bed and its laterally equivalent horizon; (2) known mined areas of the Pittsburgh Coal bed; (3) areas of inadequate subsurface control, areas of impure coal, and areas where the Pittsburgh Coal bed is absent; and (4) areas where mining has occurred and/or known resources exist.
Methods:
Areal extent of the Pittsburgh Coal bed and horizon
The areal extent of the Pittsburgh Coal bed and horizon was digitized from multiple sources using Arc-info and Arcedit. The digital maps were edited manually in Arcedit and appended to create a single GIS data set (coverage) for each state: all were combined to create a single GIS coverage for the areal extent of the Pittsburgh Coal bed and horizon.
In West Virginia, the areal extent of the bed and horizon was digitized from maps in county and other reports that show coal extents or outcrops for multiple beds at scales of 1:62,500 and 1:24,000 (see references). Because the county geologic maps of Gilmer and Kanawha Counties, WV show miscorrelations of the Pittsburgh Coal bed (B.M. Blake, West Virginia Geological and Economic Survey, oral commun., 1996) the contact between the Monongahela and Conemaugh Groups (Cardwell and others, 1968) was used for the areal extent of the Pittsburgh Coal bed and horizon. The coverage for areas of inadequate subsurface control, impure and absent Pittsburgh Coal and areas where mining has occurred and/or resources are known were obtained from three types of sources. In Wetzel, Doddridge, Gilmer, and the northwestern part of Kanawha Counties, lines labeled "Approximate edge where the Pittsburgh Coal bed of commercial thickness and purity disappears" (Hennen, 1912) were digitized from the West Virginia county report maps. In Putnam and western Braxton Counties the lines were digitized from Lotz (1970). Modifications of the published lines in the county reports and Lotz (1970) were made on the basis of geologic field work (C.B.Cecil, U.S. Geological Survey, oral commum., 1997; Nick Fedorko, West Virginia Geological and Economic Survey, oral commun., 1997) in Roane, Calhoun,Clay, eastern Kanawha, western Braxton, southern Lewis, and western Upshur Counties. In Ohio, available 1:62,500 scale maps were mosaiced into resource areas by the Ohio Division of Geological Survey (ODGS) and digitized. In southern Ohio (Resource Area 13), where coal resource maps were not available, the Monongahela/Conemaugh Group contact, as shown on the Geologic Map of Ohio (Bownocker, 1920), was used for the areal extent of the Pittsburgh Coal bed and horizon. Areas of inadequate subsurface control, impure, or absent coal and areas where mining has occurred and/or resources are known were digitized from the <14 in. isopach line delineated on isopach maps of the Pittsburgh Coal bed (Bronsdon, 1975). Because different criteria were used to delineate the lines of known resources from areas of inadequate subsurface control, impure or absent coal in Ohio and West Virginia, an offset is observed at the state boundaries. In Pennsylvania, county reports, which included reduced 1:24,000 scale maps, were digitized (see data sources). In Maryland, the cropline of the Pittsburgh Coal bed was taken from the Monongahela/Conemaugh contact on the Geologic Map of Maryland (Cleaves and others, 1968) and revised with Berryhill and others (1956) in Alleghany County and an unpublished 1:100,000 compilation map that includes Garrett County (D. Brezinski, Maryland Department of Natural Resources, Maryland Geological Survey,1997). The cropline of the Pittsburgh Coal bed was then built for polygon topology. Each polygon was labeled as either coal bearing or devoid of coal.
Mined areas of the Pittsburgh Coal bed
The mined data were acquired from various sources. The primary source in the northern part of the Pittsburgh Coal bed and horizon was a proprietary Computer Aided Design (CAD) file from the John T. Boyd Company, Pittsburgh, Pennsylvania, which provided data for Ohio, much of Pennsylvania, and northern West Virginia. Mined areas that were not included in the John T. Boyd Company map in Greene, Westmoreland, Fayette, and Allegheny Counties, Pennsylvania, were obtained from the Pennsylvania Topographic and Geologic Survey county reports (various dates). West Virginia Geological and Economic Survey Open-file mine maps (various dates) were used for the mined area coverage south of Monongalia and Marion Counties. In Maryland, the Pittsburgh Coal bed is assumed to be mined-out at the scale represented by this map (D.Brezinski, Maryland Department of Natural Resources, Maryland Geological Survey, oral commun., 1996).
The John T. Boyd map (1995) was geo-referenced using state boundaries and reference points with Arcedit, appended with digitized West Virginia data, and both data sets were cleaned manually. The three sets of data were combined to create a single coverage and built for polygon topology. Each polygon was labeled as mined or unmined. The two coverages, one for the areal extent and one for the mined areas of the Pittsburgh Coal bed were then combined in Arcedit. The boundaries of the mined coverage did not match those of the areal extent coverage. Therefore, the boundaries of the areal extent were used in lieu of the boundaries of the mined coverage. The resulting coverage, a combination of the mined and areal extent coverages, was built for polygon topology. This combined polygon coverage was then labeled by polygon in two categories. The first category defined polygons as part of the original areal extent of the Pittsburgh Coal bed. The second category showed whether or not a given polygon that was part of that original bed had been mined. This final coverage was used to produce this map.

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