The Fayetteville Shale is a geologic

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

Mississippian age The Mississippian ( ), also known as Lower Carboniferous or Early Carboniferous, is a subperiod in the geologic timescale or a subsystem of the geologic record. It is the earlier of two subperiods of the Carboniferous period lasting from rou ...

(354–323 million years ago) composed of tight

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 ...

within the

Arkoma Basin The Arkoma Basin is a peripheral foreland basin that extends from central west Arkansas to south eastern Oklahoma. The basin lies in between the Ozark Uplift and Oklahoma Platform to the north and Ouachita Mountains to the south and with an are ...

Arkansas Arkansas ( ) is a landlocked state in the West South Central region of the Southern United States. It borders Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, Texas to the southwest, and Oklahoma ...

and

Oklahoma Oklahoma ( ; Choctaw language, Choctaw: , ) is a landlocked U.S. state, state in the South Central United States, South Central region of the United States. It borders Texas to the south and west, Kansas to the north, Missouri to the northea ...

. It is named for the city of

Fayetteville, Arkansas Fayetteville ( ) is the List of cities and towns in Arkansas, second-most populous city in the U.S. state of Arkansas, the county seat of Washington County, Arkansas, Washington County, and the most populous city in Northwest Arkansas. The city ...

, and requires

hydraulic fracturing Fracking (also known as hydraulic fracturing, fracing, hydrofracturing, or hydrofracking) is a well stimulation technique involving the fracturing of Formation (geology), formations in bedrock by a pressurized liquid. The process involves the ...

to release the

natural gas Natural gas (also fossil gas, methane gas, and gas) is a naturally occurring compound of gaseous hydrocarbons, primarily methane (95%), small amounts of higher alkanes, and traces of carbon dioxide and nitrogen, hydrogen sulfide and helium ...

contained within.

Nomenclature

Named by Frederick Willard Simonds in 1891, Simonds recognized what is now the Fayetteville Shale as three separate formations overlying the now abandoned Wyman Sandstone: the Fayetteville Shale, the Batesville Sandstone, and the Marshall Shale. In 1904, the name "Fayetteville Shale" replaced all three of these names. The Fayetteville Shale that Simonds recognized is now considered as the lower Fayetteville Shale. Simonds' Batesville Sandstone was found to be the same as the Wyman Sandstone, and replaced the name "Wyman Sandstone", while Simonds' Batesville Sandstone became known as the "Wedington Sandstone Member" presumably after Wedington Mountain. The name Marshall Shale was abandoned and is now known as the upper Fayetteville Shale.

Natural gas

Gas Production from Fayetteville 2000-2013

The formation holds

in a fine-grained rock matrix which requires

to release the gas. This process became cost-effective in some shales such as the Fayetteville after years of experimentation in the

Barnett Shale The Barnett Shale is a geological formation located in the Bend Arch-Fort Worth Basin. It consists of sedimentary rocks dating from the Mississippian period (354–323 million years ago) in Texas. The formation underlies the city of Fort Worth ...

North Texas North Texas is a term used primarily by residents of the Dallas–Fort Worth metroplex to refer to a geographic area of Texas, generally considered to include the area south of Oklahoma, east of Abilene, Texas, Abilene, west of Paris, Texas, Par ...

, especially when combined with horizontal drilling. The Fayetteville Shale play began in July 2004 when

Southwestern Energy Southwestern Energy Company was a natural gas exploration and production company organized in Delaware and headquartered in Spring, Texas. In October 2024, the company merged into Expand Energy. The company's primary exploration and production ...

drilled the Thomas #1-9 vertical well in Conway County, Arkansas. In February 2005, Southwestern Energy drilled the first horizontal well, the Seeco-Vaughan #4-22H, also in Conway County. The US

Energy Information Administration The U.S. Energy Information Administration (EIA) is a principal agency of the U.S. Federal Statistical System responsible for collecting, analyzing, and disseminating energy information to promote sound policymaking, efficient markets, and pub ...

estimated that the shale play held 13,240 billion cubic ft (375 billion cubic meters) of unproved, technically recoverable gas. The average well was estimated to produce 1.3 billion cubic feet of gas. As of 2018, new drilling in the Fayetteville Shale had ceased and almost 1/5 of wells were abandoned.

Paleontology

Flora

Because the Fayetteville Formation is a marine unit, most of the plants found in the black shales must have been washed into the Carboniferous sea from a landmass. However one unit within the formation, the Weddington Sandstone Member, is a series of river deposited sand beds. Fossil plants from this unit were probably deposited closer to their source.

*'' Adiantites'' :''A. minima'' *'' Ankyropteris'' *'' Archaeocalamites'' :''A. fayettevillensis'' :''A. gracilentus'' :''A. umbralis'' :''A. wedingtonensis'' *'' Bothrodendron'' *'' Carpolithus'' :''C. inquirenda'' *'' Cardiopteris'' :''C. hirta'' *'' Chlamidostachys'' :''C. chesterianus'' *'' Lepidocystis'' :''L. chesterensis'' *''

Lepidodendron ''Lepidodendron'' is an extinct genus of primitive lycopodian vascular plants belonging the order Lepidodendrales. It is well preserved and common in the fossil record. Like other Lepidodendrales, species of ''Lepidodendron'' grew as large-tree ...

'' :''L. henbesti'' :''L. occidentale'' :''L. purduei'' :''L. wedingtonense'' *'' Lepidophloios'' *'' Lepidophyllum'' :''L. sagittatum'' *'' Lepidostrobus'' :''L. occidentalis'' *'' Lepidostrous'' Taylor, T., Eggard, D.,1967. Petrified Plants from the Upper Mississippian ( Chester Series) of Arkansas. Transactions of the American Microscopical Society. 86: 4 *'' Lyginopteris'' :''L. royalii''Tomescu, A. 2001. Lyginopteris royalii sp. nov. from the Upper Mississippian of North America. Review of Paleobotany and Palynology. 116: 3-4 *'' Medullosa'' *''

Neuropteris ''Neuropteris'' is an extinct seed fern that existed in the Carboniferous period, known only from fossils. Gallery File:Neuropteris flexuosa kz01.jpg, ''N. flexuosa'' File:Neuropteris flexuosa fossil plant (Mazon Creek Lagerstatte, Francis ...

'' *'' Pachytesta'' *'' Rhacopteris'' *'' Rhynchogonium'' :''R. fayettevillense'' *'' Rhynochosperma'' :''R. quinnii'' Dunn, M., Rothwell, G., Mapes, G. 2002.Additional observations on Rhynchosperma quinnii (Medullosaceae): a permineralized ovule from the Chesterian (Upper Mississippian) Fayetteville Formation of Arkansas. Journal of Botany. 89:11 *''

Sphenopteris ''Sphenopteris'' is a genus of seed ferns containing the foliage of various extinct plants, ranging from the Devonian to Late Cretaceous. One species, ''S. höninghausi'', was transferred to the genus '' Crossotheca'' in 1911. Biology The fro ...

'' :''S. (Palmatopteris) erectiloba'' :''S. (Calymmatotheca) mississippiana'' *''

Stigmaria ''Stigmaria'' is a form taxon for common fossils found in Carboniferous rocks. They represent the underground rooting structures of arborescent lycophytes such as ''Sigillaria'' and '' Lepidodendron'' under the order '' Lepidodendrales.'' Descr ...

'' :''S. arkansana'' :''S. wedingtonensis'' *'' Tivena'' :''T. arkansana''Dunn, M., Rothwell, G., Mapes, G. 2003. On Paleozoic plants from marine strata: Trivena arkansana (Lyginopteridaceae) gen. et sp. nov., a lyginopterid from the Fayetteville Formation (middle Chesterian/Upper Mississippian) of Arkansas, USA. Journal of Botany. 90:8

Fauna

Vertebrates

*'' Carcharopsis wortheni''Lund, R., Mapes, R. 1984. Carcharopsis wortheni from the Fayetteville Formation (Mississippian) of Arkansas. Journal of Paleontology. 58:3. *"''

Cobelodus ''Cobelodus'' is an extinct genus of cartilaginous fish known from the late Carboniferous to the early Permian period. The type specimen, assigned to the genus '' Styptobasis'', was discovered by Edward Drinker Cope in Illinois Basin black coal s ...

''" (remains now attributed to ''

Ozarcus ''Ozarcus'' is an extinct genus of symmoriiform cartilaginous fish from the Carboniferous period of Arkansas. The type species, ''Ozarcus mapesae'', was named in 2014 based on cartilaginous skulls from the Serpukhovian-age Fayetteville Formatio ...

'') Maisey, J. G. (2007). The braincase in Paleozoic symmoriiform and cladoselachian sharks. Bulletin of the American Museum of Natural History, 2007(307), 1-122. *'' Cosmoselachus mehlingi'' *'' Ozarcus mapesae''

Echinoderms

*'' Acrocrinus constrictus'' *'' Agassizocrinus conicus'' *'' Alcimocrinus ornatus'' *'' Allocatillocrinus carpenteri'' *'' Ampelocrinus erectus'' *'' Aphelecrinus exoticus'' ::*'' A. planus'' *'' Childonocrinus trinodus'' *'' Cymbiocrinus gravis'' *'' Dasciocrinus aulicus'' *'' Heliosocrinus aftonensis'' *'' Intermediacrinus modernus'' *'' Linocrinus'' *'' Mantikosocrinus castus'' *'' Onchyocrinus''Burdick, D., Strimple, H. 1973. Flexible Crinoids from the Fayetteville Formation (Chesterian) of Northeastern Oklahoma. Journal of Paleontology. 47:2 *'' Onychocrinus pulaskiensis'' *'' Ophiurocrinus hebdenensis'' *'' Pentremites platybasis'' ::*'' P. pulchellus'' *'' Phacelocrinus'' *'' Phanocrinus'' Strimple, H. 1948. Notes on Phanocrinus from the Fayetteville Formation of Northeastern Oklahoma. Journal of Paleontology. 22:4 ::*'' P. alexanderi'' ::*'' P. cylindricus'' ::*'' P. formosus'' *'' Scytalocrinus aftonensis'' *'' Taxocrinus cestriensis'' ::*'' T. whitefieldi''. *'' Ulrichicrinus chesterensis''

Cephalopods

*'' Arcanoceras furnishi'' *'' Cluthoceras glicki'' :*'' Cluthoceras pisiforme'' *'' Cravenoceras fayettevillae'' :*'' Cravenoceras lineolatum'' *'' Dombarites mapesi'' *'' Eurmorphoceras plummeri'' *'' Fayettevillea planorbis'' *'' Girtyoceras'' Doughouzhaeva L, Mapes, R., Mutvei, H. 1997. Beaks and radulae of Early Carboniferous goniatites. Lethia. 30:4 *''

Goniatites granosus ''Goniatites'' is a genus of extinct cephalopods belonging to the family Goniatitidae, included in the superfamily Goniatitaceae. '' Hibernicoceras'' and '' Hypergoniatites'' are among related genera. Species Description The shell is general ...

'' *'' Lusitanites subcircularis'' *'' Metadimorphoceras wiswellense'' *'' Neoglyphioceras crebriliratum'' *'' Paracravenoceras ozarkense'' *'' Paradimorphoceras'' *'' Pronorites baconi'' *'' Rayonnoceras solidiforme'' Mapes, R. 1966. Late Mississippian Lycopsid Branch from Arkansas. Oklahoma Geology Notes. *'' Tumulites varians''

Corals

*'' Amplexus expansus'' Easton, W. 1945. Kinkaid Corals from Illinois and Amplexoid Corals from the Chester of Illinois and Arkansas. Journal of Paleontology. 19:4 *'' Michelinia meekana'' Sando, W. 1969. Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part B- Corals. United States Geologic Survey Professional Paper 606 *'' Palaecris carinata''

Bivalves

200px, ''Aviculopecten subcardiformis'' from the Logan Formation (Lower Carboniferous) of Wooster, Ohio">Carboniferous.html" ;"title="Logan Formation (Lower Carboniferous">Logan Formation (Lower Carboniferous) of Wooster, Ohio (external mold). *''Aviculopecten, Aviculopecten squamula'' :*''Aviculopecten, Aviculopecten jennyi'' :*''Aviculopecten, Aviculopecten multilineatus'' :*'' Aviculopecten morrowensis'' :*'' Aviculopecten inspeciosus'' *'' Canyella peculiaris'' *'' Cardiomorpha inflata'' *'' Conocardium peculiare'' *'' Cypricardia fayettevillensis'' *'' Cyprecardella sublata'' *'' Edmondia equilateralis'' *'' Palaeoneilo sera'' *'' Phestia stevensiana'' Sanguinolites simulans'' *'' Solenamorpha nitida'' Pojeta, J. 1969. Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part C- Pelecypods. United States Geologic Survey Professional Paper 606 *'' Sphenotus branneri'' :*'' Sphenotus washingtonensis'' :*'' Sphenotus dubius'' :*'' Sphenotus meslerianus''

Brachiopods

*'' Adairia adairensis''M. Gordon Jr. and T. W. Henry. 1993. Late Mississippian Productoid Brachiopods Inflatia, Keokukia, and Adairia, Ozark Region of Oklahoma and Arkansas. Paleontological Society Memoir 30:1-29 *'' Inflatia gracilis'' :*'' Inflatia cherokeensis'' :*'' Inflatia pusilla'' :*'' Inflatia inflata'' *'' Orthotetes protensus'' :*'' Orthotetes subglobosus''

Gastropods

*'' Euconospira disjuncta'' *'' Mourlonia lativittata'' *'' Patellilabia laevigata'' *'' Platyceras subelegans'' :*'' Platyceras compressum'' *'' Sinuitina venata'' Yochelson, E 1969. Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part C- Pelecypods. United States Geologic Survey Professional Paper 606 *'' Trepospira discus''

Arthropods

*'' Amphissites'' *'' Bairdia'' *'' Cyrtoproetus kerhini'' *'' Kirkbya'' Sohn, I. 1969.Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part F- Ostracodes. United States Geologic Survey Professional Paper 606 *'' Geisina'' *'' Glyptopleura'' *'' Graphiadactyllis'' *'' Orthobairdia'' *'' Paladin murconatus'' Gordon, M. 1969.Revision of Some of Girty's Invertebrate Fossils from the Fayetteville Shale (Mississippian) of Arkansas and Oklahoma: Part E- Trilobites. United States Geologic Survey Professional Paper 606 *'' Paraparchites'' *'' Roundyella'' *'' Sansabella'' *'' Serenida''

Ostracods

*'' Cavellina'' *'' Kegelites'' *'' Sargentina''

Bryozoans

Foraminifera

*''

Earlandia ''Earlandia'' was a genus of prehistoric foraminifera. See also * Arthur Earland (1866–1958), a British oceanographer, microscopist and expert on Foraminifera * List of prehistoric foraminifera genera References External links * ...

'' *'' Eosigmoilina rugosa''

Trace Fossils

Cruziana ''Cruziana'' is a trace fossil (fossil records of lifeforms' movement, rather than of the lifeforms themselves) consisting of elongate, bilobed, approximately bilaterally symmetrical burrows, usually preserved along bedding planes, with a sculp ...

Planolites ''Planolites'' is an ichnogenus found throughout the Ediacaran and the Phanerozoic that is made during the feeding process of worm-like animals. The traces are generally small, , unlined, and rarely branched, with fill that differs from the host ...

Teichichnus ''Teichichnus'' is an ichnogenus with a distinctive form produced by the stacking of thin 'tongues' of sediment, atop one another. They are believed to be fodinichnia, with the organism adopting the habit of retracing the same route through var ...

References

{{Shale gas Mississippian Arkansas Serpukhovian Shale formations of the United States Oil-bearing shales in the United States Natural gas fields in the United States Carboniferous System of North America Carboniferous southern paleotropical deposits Sandstone formations of the United States Limestone formations of the United States