St. Clair Limestone

The St. Clair Limestone is a geologic formation in Arkansas, Indiana, Missouri, and Oklahoma. It preserves fossils dating back to the Silurian period. This high density, high magnisium dolomitic limestone[2] was originally classified as a marble in Oklahoma due to the fact that it would hold a high polish, hence Marble City.

St. Clair Limestone Stratigraphic range: Silurian
Type	Formation
Underlies	Lafferty Limestone in Arkansas and Moccasin Springs Formation in Illinois, Indiana, and Missouri
Overlies	Brassfield Limestone in Arkansas and Sexton Creek Limestone in Illinois, Indiana, and Missouri
Lithology
Primary	Limestone
Location
Region	Arkansas, Illinois, Indiana, and Missouri
Country	United States
Type section
Named for	St. Clair spring, Independence County, Arkansas[1]
Named by	Richard Alexander Fullerton Penrose Jr.

Physical characteristics

		Imperial	Metric
Absorption by weight	ASTM C97	0.5%	0.5%
Density	ASTM C97	168 lb/ft3	2 691.10 kg/m3
Compressive strength	ASTM C170	15 889Psi	109.55MPa
Modulus of rupture	ASTM C99	972Psi	6.70MPa

[3]

Paleofauna

Brachiopods

Ancillotoechia A. marginata[4] Antirhynchonella A. thomasi [4] Atrypa [4] Atrypina [4] A. erugata [4] Boucotides B. barrandei [4] Brachymimulus B. americanus [4] B. elongatus [4] Cymostrophia [4] Dicamaropsis D. parva [4] Dicoelosia D. bilobella [4]

Dolrorthis D. nanella [4] Eospirifer E. acutolineatus acutolineatus [4] E. acutolineatus pentagonus [4] Hircinisca H. havliceki [4] Homoeospirella H. costatula arkansana [4] H. pygmaea [4] Howellella H. splendens [4] Kozlowskiellina K. vaningeni [4] Leangella L. (Opikella) dissiticostella [4] Leptaena [4]

Lissostrophia [4] Meristina M. clairensis [4] Nanospira N. clairensis [4] Nucleospira N. raritas [4] Onychotreta O. angustata [4] O. lenta [4] O. (Eilotreta) miseri [4] O. multiplicata [4] O. (Lissotreta) plicata [4] Orthostrophella O. clairensis [4] Oxoplecia O. infrequens [4]

Parastrophinella P. lepida [4] Placotriplesia P. juvenis [4] P. praecipta [4] Plectatrypa P. arctoimbricata [4] Plectodonta [4] Plicocyrtia P. arkansana [4] Resserella [4] Shaleria [4] Streptis S. glomerata [4] Virginiata V. arkansana [4]

Conodonts

Acodus A. inornatus[5] A. unicostatus[5] Ambalodus A. triangularis[5] Belodella B. flexa[5] Belodina B. inclinata[5] Carniodus[5] C. carnulus[5] C. carnus[5] Cordylodus C. delicatus[5] C. flexuosus[5]

Distacodus D. mehli[5] D. posterocostatus[5] D. procerus[5] Distomodus D. kentuckyensis[5] Drepanodus D. homocurvatus[5] Hadrognathus H. staurognathoides[5] Hindeodella H. equidentata[5] Ligonodina L. egregia[5] L. silurica[5]

Neoprioniodus N. costatus[5] N. excavatus[5] N. multiformis[5] N. subcarnus[5] Oistodus O. inclinatus[5] Ozarkodina O. gaertneri[5] O. inclinata[5] O. media[5] O. ziegleri[5] Paltodus P. multicostatus[5] P. trigonius[5]

Panderodus P. gracilis[5] P. simplex[5] P. unicostatus[5] Plectospathodus P. extensus[5] Pterospathodus P. amorphognathoides[5] Spathognathodus S. ranuliformis[5] S. rhenanus[5] S. wolfordi[5] Trichonodella T. brassfieldensis[5] T. carinata[5] T. exacta[5] T. variflexa[5]

Trilobites

Ananaspis[6] Balizoma [6] Cheirurus C. phollikodes [6] C. prolixus [6] Cornuporoetus C. kyphora [6] Dalmanites D. howelli [6] D. ptyktorhion [6]

Decoroproetus D. anaglyptus [6] D. corycoeus [6] Deiphon D. longifrons [6] Delops [6] Diacalymene D. altirostris [6] Encrinurus E. egani [6]

Eophacops E. fontana [6] Harpidella H. butorus [6] H. spinulocervix [6] Lepidoproetus L. (Dipharangus) xeo [6] Proetidae [6] Proetus P. vaningeni [6]

Radnoria [6] Raphiophorus R. niagarensis [6] Sphaerexochus S. glaber [6] Staurocephalus S. lagena [6] S. oarion [6] Sthenarocalymene S. scutula [6] Tropidocoryphinae [6]

See also

• List of fossiliferous stratigraphic units in Arkansas
• Paleontology in Arkansas

References

1. Penrose Jr., R.A.F. (1891). "Manganese: its uses, ores, and deposits". Annual Report of the Geological Survey of Arkansas for 1890. 1: 101–102, 112–114, 124–128, 166–203, 214–215.
2. Schrenk, Steven (September 2017). "The Grey American Limestone that Acts Like a Marble". The Slippery Rock Gazette: 36, 37.
3. "Saint Clair Linear | Polycor | Natural Stone | North America | Limestone". Polycor. Retrieved 2017-10-13.
4. Amsden, Thomas W. (1968). "Articulate Brachiopods of the St. Clair Limestone (Silurian), Arkansas, and the Clarita Formation (Silurian), Oklahoma". Memoir (The Paleontological Society). 1: i–117. JSTOR 1315506.
5. Craig, William (1968). The stratigraphy and conodont paleontology of Ordovician and Silurian strata, Batesville district, Independence and Izard counties, Arkansas (PhD). The University of Texas.
6. Holloway, David J. (January 1980). "Middle Silurian trilobites from Arkansas and Oklahoma, USA., Part I". Palaeontographica Abteilung A. 170: 1–85.

• Various Contributors to the Paleobiology Database. "Fossilworks: Gateway to the Paleobiology Database". Archived from the original on 31 July 2014. Retrieved 8 July 2014.