STRATIGRAPHY AND REGIONAL FACIES RELATIONS OF THE PENNSYLVANIAN MONONGAHELA GROUP AND THE PERMO-PENNSYLVANIAN DUNKARD GROUP, APPALACHIAN BASIN

The upper Pennsylvanian Monongahela Group and the Permo-Pennsylvanian Dunkard Group strata are preserved in the northeast-southwest trending Pittsburgh-Huntington Synclinorium and are bounded by erosion on all sides. The Monongahela and Dunkard Group are comprised of interbedded gray, green, and red shale, gray, green and red claystone and mudstone, nonmarine limestone, immature, fine grained sandstones, siltstones, and coals. There are no known marine beds in these rocks, although the brackish form Lingula has been found in shale associated with the Washington coal bed (Dunkard Group) in Ohio and nearby areas of West Virginia. Calcareous material is common in siliciclastic facies both as nodules and in disseminated form. Economically important coal beds are present in the Monongahela Group, notably the Pittsburgh, Sewickley and Waynesburg coal beds. The Washington coal is locally minable. Nonmarine limestones are more common and in thicker sequences in the Monongahela Group than in the Dunkard Group. Red beds are also less common in the Monongahela Group and more common in the Dunkard Group, but the limestones and coals thin out and disappear to the south in both groups, replaced by sandstone, red shale, and red claystone and mudstone. The Monongahela and Dunkard Groups thin from south to north.

A cross section constructed with core logs spanning approximately 100 miles from Jackson County, WV to near Wheeling, WV illustrates these regional facies relations and shows the correlation of selected stratigraphic units.