The Silurian Clinton Group is a mapped bedrock unit in New York, Pennsylvania, Maryland, and West Virginia. It contains the Rose Hill Formations, and the ridge-forming Keefer Formation sandstone. Other names for the members are Reynales Limestone, Williamson Shale, Irondequoit Limestone, and Rochester ShaleRyder, Robert T. et al.. "Possible Continuous-Type (Unconventional) Gas Accumulation in Lower Silurian "Clinton" Sands, Medina Group, and the Tuscarora Sandstone in the Appalachian Basin: A Progress Report of 1995 project activities". USGS

The Clinton Group is defined as a brownish-gray to olive-gray shaly claystone, and a thinly-bedded, fine-grained sandstone, with dark red, fine-grained “iron” sandstone also present. It is approximately 1640 feet thick. The Rochester Shale is a Gray, thin-bedded calcareous shale and dark gray, thin- to medium-bedded lenticular limestone. The Keefer Sandstone is a White to yellowish-gray, thick-bedded protoquartzite and orthoquartzite. The Rose Hill Formation is Olive-gray to drab, thin-bedded sandstone."Geologic Maps of Maryland:" The Keefer sandstone has limestone-like properties, because it contains calcite and fossils in addition to quartz.

The Keefer sandstone also contains a bed of oolitic hematite from a thick paleosoil that formed on the Gatesburg Formation, which provided iron for the 19th century stone blast furnaces found throughout Central Pennsylvania."Field Trip: From tropical shorelines to glacial ice fields, with orogeny mixed in, and all on Tussey Mountain: 400 million years of history". CALL Course on Geology and Environmental Geology of the State College Area. Pennsylvania State University Department of Geosciences, In Maryland, the Rose Hill Formation contained the Cresaptown Iron Sandstone.

Relative age dating of the Clinton Group places it in the Lower Silurian period. It rests conformably atop the Tuscarora Formation and conformably below the Lower and Upper Silurian Lockport Group and Bloomsburg Formation.Jackson, Margaret S.; Hanley, Peter M.; and Sak, Peter B. (2007). "Preliminary Bedrock Geologic Map of the Middle Portion of the Susquehanna River Valley, Cumberland, Dauphin, And Perry Counties, Pennsylvania" (pdf). Open File Report OFBM-07-05.0. Pennsylvania Geological Survey

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