The Pope Mega Group is a geologic unit found in the

Illinois Basin The Illinois Basin is a Paleozoic depositional and structural basin in the United States, centered in and underlying most of the state of Illinois, and extending into southwestern Indiana and western Kentucky. The basin is elongate, extending a ...

of southern

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. It borders on Lake Michigan to its northeast, the Mississippi River to its west, and the Wabash River, Wabash and Ohio River, Ohio rivers to its ...

, southwestern

Indiana Indiana ( ) is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders Lake Michigan to the northwest, Michigan to the north and northeast, Ohio to the east, the Ohio River and Kentucky to the s ...

, and western

Kentucky Kentucky (, ), officially the Commonwealth of Kentucky, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Illinois, Indiana, and Ohio to the north, West Virginia to the ...

.Stamm, N. 2020b
''Geologic Unit: Menard, National Geologic Map Database''''Geolex'', United States Geological Survey, Reston, Virginia.
/ref>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. In

and

its equitant is the Buffalo Wallow Group. This unit grades from

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

s at its base into mix of

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s and sandstone and then a

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

at its top. In Southern Illinois oil wells are drilled into the Tar Springs formation.

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.

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 A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

in the

of southern

, southwestern

, and western

. 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 The Illinois Central Railroad , sometimes called the Main Line of Mid-America, is a railroad in the Central United States. Its primary routes connected Chicago, Illinois, with New Orleans, New Orleans, Louisiana, and Mobile, Alabama, and thus, ...

.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.

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

, Indiana and

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

Hardinsburg Formation

The Hardinsburg Formation is a

, Indiana and

. It preserves

dating back to the

Haney Formation

The Haney Formation is a

, Indiana and

. It preserves

dating back to the

References

{{Carboniferous footer, state=expanded Carboniferous Illinois Carboniferous Indiana Carboniferous Kentucky Sandstone groups of the United States Limestone groups of the United States Shale groups of the United States Geologic groups of Illinois Geologic groups of Indiana Geologic groups of Kentucky