Clinton Group

Clinton Group Stratigraphic range: Late Silurian
Rocks of the Clinton Group on the east face of Schuylkill Gap
Type	sedimentary
Sub-units	Rochester Shale, Rose Hill Formation, Keefer Formation
Underlies	Bloomsburg Formation
Overlies	Tuscarora Formation
Thickness	1640 ft
Lithology
Primary	sandstone
Other	shale
Location
Region	Appalachian Mountains
Country	United States
Extent	Pennsylvania, Maryland, New York, West Virginia

The Silurian Clinton Group is a mapped bedrock unit in New York, Pennsylvania, Maryland, and West Virginia. It contains the Rochester Shale, Rose Hill Formation^[1] and the ridge-forming Keefer Formation.^[2] Other names for the members are Reynales Limestone, Williamson Shale, Irondequoit Limestone, and Rochester Shale^[2]

Description

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.^[1] 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.^[3] The Keefer sandstone has limestone-like properties, because it contains calcite and fossils in addition to quartz.^[4]

Economic uses

In Maryland, the Rose Hill Formation contained the Cresaptown Iron Sandstone.^[3]

Age

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^[2] and Bloomsburg Formation.^[1]

References

1. ^ ^{a b c} 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. http://www.dcnr.state.pa.us/topogeo/openfile/midsusque.pdf. Retrieved 2008-01-26. 
2. ^ ^{a b c} Ryder, 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. http://pubs.usgs.gov/of/1996/of96-042/sandston.htm. Retrieved 2008-01-26. 
3. ^ ^{a b} "Geologic Maps of Maryland:". http://www.mgs.md.gov/esic/geo/lgdalleg.html. Retrieved 2008-01-26. 
4. ^ "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,. http://www.geosc.psu.edu/public/CALL/2007trips/Tussey_trip.htm. Retrieved 2008-01-26. 

See also

• Geology of Pennsylvania

Coordinates: 40°44′05″N 77°46′42″W / 40.73472°N 77.77833°W / 40.73472; -77.77833