Type Sedimentary Named by H. D. Rogers, 1840 Overlies Pottsville Formation Primary Sandstone, Coal | Country United States Region Appalachian Mountains Underlies Catskill Formation | |
Extent Pennsylvania, Maryland, West Virginia, Ohio | ||
The Pennsylvanian Allegheny Formation is a mapped bedrock unit in western and central Pennsylvania, western Maryland and West Virginia, and southeastern Ohio. It is a major coal-bearing unit in the Appalachian Plateau of the eastern United States.
Contents
Description
In Pennsylvania, the Allegheny Formation includes rocks from the base of the Brooksville Coal to the top of the Upper Freeport Coal, and was defined to include all economically significant coals in the upper Pennsylvanian sequence. The formation consists of cyclothemic sequences of coal, shale, limestone, sandstone, and clay. It contains six major coal zones, which, in stratigraphic order, are:
Members
Glen Richey (PA), Laurel Run (PA), Mineral Springs (PA), Millstone Run (PA), Clearfield Creek (PA); Clarion (OH, MD, PA, WV), Kittanning (PA), Freeport (PA, MD, OH, WV); Putnam Hill (OH, PA); Vanport (PA, MD, OH, WV); Butler (MD, PA), Worthington (MD, PA); Washingtonville (OH, PA, WV), Columbiana (OH)
Age
Relative age dating of the Allegheny places it in the middle Pennsylvanian period.