The Pennsylvanian Pottsville Formation is a mapped bedrock unit in Pennsylvania, western Maryland, West Virginia, Ohio, and Alabama.

The Pottsville Formation consists of a gray conglomerate, fine to coarse grained sandstone, and is known to contain limestone, siltstone and shale, as well as anthracite and bituminous coal.

[4] The relationship to the term "Pottsville" and actual lithologic units is complex.

[8] A 1.3-m interval at the base of the Pottsville in the Broad Top basin in Pennsylvania contains both marine invertebrates and plant fossils of middle Morrowan age.

[9] Relative age dating of the Pottsville places it in the Early to Middle Pennsylvanian period.