Hamilton Group

[6] In western Pennsylvania, Ohio and West Virginia the Hamilton Group consists of the Mahantango Formation, a gray, dark gray, brown, and olive laminated shale; siltstone; and very fine-grained sandstone or claystone containing marine fossils.

[8] In New York, central and eastern Pennsylvania the upper sections contain several thick grey shale formations, occasionally marked with limestone stringer.

Depths ranging from outcrops to 8,000 feet below the surface of Sullivan County, in the southeastern part of New York state.

[8] The Marcellus Formation contains a local limestones Purcell Member and Cherry Valley as well as Tioga Bentonites at the base in central and eastern Pennsylvania.

[15][12] Source:[17] Tropidoleptus carinatus Nucfeospira concinna Mucrospirifer Athyris Pleurodictyum americanum Orthonota undulate Dipleura

The Hamilton is a good source of road material, riprap and building stone,[18] that is used locally for shale aggregate and common fill.