Pope Mega Group

The Pope Mega Group is a geologic unit found in the Illinois Basin of southern Illinois, southwestern Indiana, and western Kentucky.^[1][2] In Indiana and Kentucky its equitant is the Buffalo Wallow Group. This unit grades from sandstones at its base into mix of limestones and sandstone and then a shale at its top.^[3] In Southern Illinois oil wells are drilled into the Tar Springs formation.^[4]

Pope Mega Group
Stratigraphic range: Carboniferous
Type	Geological group
Sub-units	Grove Church Shale Kincaid Goreville Limestone Cave Hill Shale Negli Creek Limestone Degonia Sandstone Clore Limestone Ford Station Limestone Tygett Sandstone Cora Limestone Palestine Sandstone Menard Limestone Allard Limestone Scottsburg Limestone Walche Limestone Waltersburg Formation Vienna Limestone Tar Springs Sandstone Glen Dean Formation Hardinsburg Formation Haney Formation Fraileys Formation Big Clifty Member Beech Creek Formation Cypress Formation Ridenhower Formation Reelsville Member Sample Member Beaver Bend Member Bethel Formation Downeys Bluff Formation Yankeetown Formation Renault Formation Shellersville Member Levias Member Aux Vases Formation
Overlies	Mammoth Cave Group
Lithology
Primary	Sandstone, Limestone, Shale
Location
Region	Illinois Basin
Country	United States of America

Stratigraphy

Kinkaid Formation

Also known at the Kinkaid Limestone, this unit is made up of several smaller members. This unit ranges from 0' - 230 ' thick. The Grove Church Shale is at the top, followed by Members, Goreville Limestone, Cave Hill Shale, and Negli Creek Limestone.

Tobinsport Formation

A formation in Illinois containing 4 members that are linked to other formations in the Upper Pope Group. The Negli Creek Limestone of the Kinkaid formation to the west. Mt. Pleasant Sandstone, Bristow Sandstone, and Siberia Limestone. The Siberia is a thin tongue of the Menard formation.^[5]

Degonia Formation

This sandstone unit is 0-150' thick.

Clore Formation

This unit is 0-150’ thick. Its units include the Ford Station Limestone, Tygett Sandstone and Cora Limestone Members.

Palestine Formation

This sandstone unit is 0-120' thick.

Menard Formation

The Menard Limestone is a geologic formation in the Illinois Basin of southern Illinois, southwestern Indiana, and western Kentucky.

The type section of both the Walche Limestone Member and the Scottsburg Limestone Member are exposures in Walche's Cut, a railway cutting on the Illinois Central Railroad.^[6][7][8]

Waltersburg Formation

This formation is 0-100’ thick.

Vienna Formation

This limestone unit is 0-60' thick

Tar Springs Formation

This sandstone unit is 0-150' thick. The Tar Springs consists of interbedded sandstone and shale, creating closed reservoirs within the sand. For this reason it is the largest oil producing formation in Illinois. Estimated to have accounted for more than 60% of the oil production in the state.

Glen Dean Formation

The Glen Dean Formation is a geologic formation in Illinois, Indiana and Kentucky. It preserves fossils dating back to the Carboniferous period.

Hardinsburg Formation

The Hardinsburg Formation is a geologic formation in Illinois, Indiana and Kentucky. It preserves fossils dating back to the Carboniferous period.

Haney Formation

The Haney Formation is a geologic formation in Illinois, Indiana and Kentucky. It preserves fossils dating back to the Carboniferous period.

Fraileys Formation

The Fraileys Formation or Fraileys Shale is a geologic formation in Illinois. It preserves fossils dating back to the Carboniferous period.

Beech Creek Formation

The Beech Creek Formation is a geologic formation in Illinois, Indiana and Kentucky. It preserves fossils dating back to the Carboniferous period.

Cypress Formation

The Cypress Formation is a geologic formation in Illinois, Indiana and Kentucky. It preserves fossils dating back to the Carboniferous period.

Ridenhower Formation

The Ridenhower Formation is a geologic formation in Illinois. It preserves fossils dating back to the Carboniferous period. It includes the Reelsville Member, Sample Member and Beaver Bend Member.

Bethel Formation

The Bethel Formation is a geologic formation in Illinois, Indiana and Kentucky. It preserves fossils dating back to the Carboniferous period.

Energy Production

References

1. Stamm, N. 2020b, Geologic Unit: Menard, National Geologic Map Database, Geolex, United States Geological Survey, Reston, Virginia.
2. Willman, H.B., Atherton, Elwood, Buschbach, T.C., Collinson, Charles, Frye, J.C., Hopkins, M.E., Lineback, J.A., and Simon, J.A., 1975, Handbook of Illinois stratigraphy: Illinois Geological Survey Bulletin, no. 95, 261 p.
3. Kolata, D.R. 2005, Bedrock Geology of Illinois: Champaign, Ill. U.S. Geological Survey (Report). Retrieved 16 December 2023.
4. Askari, Zohreh; Lasemi, Yaghoob (16 December 2022). "Geological characterization and ROZ potential of the Tar Springs Sandstone". U.S. Department of Energy Office of Scientific and Technical Information.
5. Gray, Henry H. (1978). Buffalo Wallow Group Upper Chesterian (Mississippian) of Southern Indiana (Report). Indiana Geological & Water Survey.
6. "Walche Limestone Member". igws.indiana.edu.
7. Swann, David Henry (November 17, 1963). "Classification of Genevievian and Chesterian (late Mississippian) rocks of Illinois". Report of Investigations No. 216 – via www.ideals.illinois.edu.
8. Droste, J. B., and Keller, S. J., 1995, Subsurface stratigraphy and distribution of oil fields of the Buffalo Wallow Group (Mississippian) in Indiana: Indiana Geological Survey Bulletin 63, 24 p.