Eyam Limestone

The Eyam Limestone (formerly known as the Cawdor Group, Cawdor Limestone or Eyam Group) is a geologic formation in the Peak District, England. It preserves fossils dating back to the Viséan stage of the Carboniferous period, and represents a marine environment.[2]

Eyam Limestone
Stratigraphic range: Early Carboniferous (Uppermost Viséan), [1]
Eyam Limestone in Wirksworth
TypeGeological formation
Unit ofPeak Limestone Group
UnderliesLongstone Mudstone Formation
OverliesMonsal Dale Limestone Formation
AreaDerbyshire
Thickness9 to 54 m[2]
Lithology
PrimaryLimestone
Location
Region England
Country United Kingdom
ExtentPeak District
Type section
Named forEyam

Depositional environment

At the time of deposition, Britain was just south of the equator (<5° S) and part of the Euramerica continent. Study of the growth rings of fossil wood from other localities indicate that the British Isles had a monsoonal climate during the early Carboniferous, with tropical rainfall seasonality.[3] The Eyam Limestone was deposited on an extensive, thick carbonate ramp and platform on the northeast margin of the Widmerpool Gulf (an extensive basin which existed as an area of open water during the time of deposition). Reefs and their associated fore-reef and lagoonal environments are represented in the Eyam Limestone, with crinoids dominating the reef and providing habitats for other animals. The presence of photosymbiotic coral and micritic envelopes on some crinoid ossicles indicates the formation was deposited within the photic zone in a marine environment of normal salinity. The presence of the xenacanth Bransonella has been suggested to imply freshwater influence as xenacanths live mainly in freshwater habitats, however its presence in other marine formations suggests that Bransonella was a marine animal unlike its relatives.[1]

Apatite crystals formed by the recrystallization of phosphatic overgrowths are present on some conodont elements from the formation. As phosphatogenesis only occurs in the anoxic-oxic boundary while apatite precipitation occurs in the top few centimeters of the sediment column, this reveals that shallow sediment with low geothermal temperatures and dysoxic conditions were present in the Eyam Limestone.[1][4]

Fossil content
Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
 Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Cartilaginous fish
Cartilaginous fish reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Acanthorhachis A. cf. spinatus Steeplehouse Quarry.[1] Basal body & spines.[1] A listracanthid.
Anachronistes A. fordi Steeplehouse Quarry.[5] Teeth.[5] Junior synonym of Cooleyella.
Bransonella B. nebraskensis Steeplehouse Quarry & Cawdor Quarry.[1][6] Teeth.[1][6] A xenacanth.
Carcharopsis C. prototypus Steeplehouse Quarry & Coleshill Quarry.[1][7] Teeth.[1][7] A squatinactiform.
Cladodus C. sp. Steeplehouse Quarry.[1] 4 teeth.[1] A cladoselachid.
Cooleyella C. fordi Steeplehouse Quarry & Cawdor Quarry.[1][5][6] Teeth.[1][5][6] An anachronistid.
"Ctenacanthus" "C." costellatus Steeplehouse Quarry.[1] Partial tooth.[1] A ctenacanth.
Ctenoptychius C. lobatus Steeplehouse Quarry.[1] 3 teeth.[1] A petalodont.
Cypripediodens C. cristatus Once-a-week Quarry.[8] Teeth.[8] A petalodont.
Denaea D. cf. fournieri Steeplehouse Quarry & Cawdor Quarry.[1][6] Teeth.[1][6] A falcatid.
Euchondrocephali gen. et. sp. indet. Indeterminate Cawdor Quarry.[6] Teeth.[6] Somewhat similar to orodontid teeth.
Euselachii gen. et. sp. indet. Indeterminate Cawdor Quarry.[6] Tooth.[6] An indeterminate euselachian.
Ginteria G. fungiforma Cawdor Quarry.[6] Teeth.[6] An anachronistid.
Lissodus L. wirksworthensis Teeth.[9] Reassigned to the genus Reesodus.
Petalorhynchus P. psittacinus Steeplehouse Quarry.[1] Crown & smaller tooth fragment.[1] A petalodont.
Petrodus P. patelliformis Steeplehouse Quarry.[1] Thousands of dermal denticles.[1] A symmoriid and the most abundant vertebrate in the formation.
Reesodus R. wirksworthensis Steeplehouse Quarry.[1] Tooth.[1] A hybodont.
Saivodus S. striatus Steeplehouse Quarry.[1] Tooth.[1] A ctenacanth.
Squatinactis S. caudispinatus Cawdor Quarry.[6] 4 teeth.[6] A squatinactiform.
Thrinacodus T. dziki Steeplehouse Quarry & Cawdor Quarry.[1][6] Teeth.[1][6] A phoebodont.

Conodonts
Conodonts reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Gnathodus G. girtyi Steeplehouse Quarry.[1] Partial S element.[1] An idiognathodontid.
?Hindeodus ?H. sp. Steeplehouse Quarry.[1] P1 element fragment.[1] An anchignathodontid.
?Idioprioniodus ?I. sp. Steeplehouse Quarry.[1] Two P1 element fragments.[1] A prioniodinid.
Kladognathus K. sp. Steeplehouse Quarry.[1] M element.[1] A coelodontid.
Lochriea L. commutata Steeplehouse Quarry.[1] Two P1 elements.[1] A spathognathodontid.
L. mononodosa Steeplehouse Quarry.[1] P1 element.[1] A spathognathodontid.
L. sp. Steeplehouse Quarry.[1] Two P2 elements.[1] A spathognathodontid.

Arthropods
Arthropods reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Cummingella C. cf. carringtonensis Monyash.[10] A phillipsiid trilobite.
C. sampsoni Stoney Middleton & near Hassop.[11] Multiple specimens.[11] A phillipsiid trilobite.
C. cf. tuberculingenata Monyash.[10] A phillipsiid trilobite.
Griffithides G. whitewatsoni Stoney Middleton.[11] Multiple specimens.[11] A proetid trilobite.

Brachiopods
Brachiopods reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Acanthoplecta A. mesoloba Monyash.[10] A productid.
Alitaria A.? panderi Monyash.[10] A productid.
A. sp. Monyash.[10] A productid.
Antiquatonia A. hindi Monyash.[10] A productid.
A. cf. hindi Monyash.[10] A productid.
A. cf. insculpta Monyash.[10] A productid.
A. sulcata Monyash.[10] A productid.
A. sp. Monyash.[10] A productid.
Avonia A. aculeata Monyash.[10] A productid.
A. davidsoni Monyash.[10] A productid.
A. youngiana Monyash.[10] A productid.
A. cf. youngiana Monyash.[10] A productid.
A. sp. Monyash.[10] A productid.
Brachythyris B. ovalis Monyash.[10] A spiriferid.
B. cf. ovalis Monyash.[10] A spiriferid.
Buxtonia B. sp. Monyash.[10] A productid.
Coledium C. sp. Monyash.[10] A rhynchonellid.
Dictyoclostus D. sp. Monyash.[10] A productid.
Echinoconchus E. punctatus Monyash.[10] A productid.
E. subelegans Monyash.[10] A productid.
Eomarginifera E. cf. lobata Monyash.[10] A productid.
E. longispinus Monyash.[10] A productid.
Fluctuaria F. undata Monyash.[10] A productid.
Fusella F. sp. Monyash.[10] A spiriferid.
Girtyella G. sacculus Monyash.[10] A terebratulid.
Hustedia H. ulothrix Monyash.[10] An athyridid.
Kochiproductus K. sp. Monyash.[10] A productid.
Krotovia K. spinulosa Monyash.[10] A productid.
Linoproductoidea indet. Indeterminate Monyash.[10] A productid.
Linoprotonia L. sp. Monyash.[10] A productid.
Marginicinctus M. sp. Monyash.[10] A productid.
Marginiferoidea indet. Indeterminate Monyash.[10] A productid.
Martinia M. sp. Monyash.[10] A spiriferid.
Orthoidea indet. Indeterminate Monyash.[10] An orthid.
Overtonia O. fimbriata Monyash.[10] A productid.
Pleuropugnoides P. pleurodon Monyash.[10] A rhynchonellid.
P. sp. Monyash.[10] A rhynchonellid.
Productina P. margaritacaea Monyash.[10] A productid.
P. sp. Monyash.[10] A productid.
Productus P. productus Monyash.[10] A productid.
P. sp. Monyash.[10] A productid.
Pugilis P. cf. pugilis Monyash.[10] A productid.
P. sp. Monyash.[10] A productid.
Pugnax P. acuminatus Monyash.[10] A rhynchonellid.
P. codiformis Monyash.[10] A rhynchonellid.
P. pseudopugnus Monyash.[10] A rhynchonellid.
P. cf. pugnoides Monyash.[10] A rhynchonellid.
P. sp. Monyash.[10] A rhynchonellid.
Pustula P. sp. Monyash.[10] A productid.
Rugosochonetes R. sp. Monyash.[10] A productid.
Schizophoria S. resupinata Monyash.[10] An orthid.
S. sp. Monyash.[10] An orthid.
Sinuatella S. cf. sinuata Monyash.[10] A productid.
S. sp. Monyash.[10] A productid.
Spirifer S. bisulcatus Monyash.[10] A spiriferid.
S. cf. bisulcatus Monyash.[10] A spiriferid.
S. planicostus Monyash.[10] A spiriferid.
S. triangularis Monyash.[10] A spiriferid.
Spiriferoidea indet. Indeterminate Monyash.[10] A spiriferid.

Bryozoans
Bryozoans reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Fenestelloidea Indeterminate Monyash.[10]

Cnidarians
Cnidarians reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Diphyphyllum D. sp. Monyash.[10] A horn coral.

Echinoderms
Echinoderms reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Crinoidea indet. Indeterminate Monyash.[10]

Molluscs
Molluscs reported from the Eyam Limestone
GenusSpeciesPresence MaterialNotesImages
Aviculopecten A. interstitialis Monyash.[10] A bivalve.
Aviculopinna A. mutica Monyash.[10] A pinnid bivalve.
Bivalvia indet. Indeterminate Monyash.[10] A bivalve.
Conocardium C. sp. Monyash.[10] A rostroconch.
Girtypecten G. stellaris Monyash.[10] A bivalve.
Leiopteria L. sp. Monyash.[10] A bivalve.
Parallelodon P. sp. Monyash.[10] A parallelodontid bivalve.
Pinna P. flabelliformis Monyash.[10] A pinnid bivalve.

See also

References
  1. Smith, Roy; Martill, David M.; Duffin, Christopher (1 June 2017). "The shark-beds of the Eyam Limestone Formation (Lower Carboniferous, Viséan) of Steeplehouse Quarry, Wirksworth, Derbyshire, UK". Proceedings of the Geologists' Association. 128 (3): 374–400. doi:10.1016/j.pgeola.2017.04.004. ISSN 0016-7878.
  2. "BGS Lexicon of Named Rock Units - Result Details". webapps.bgs.ac.uk. Retrieved 1 September 2023.
  3. Falcon-Lang, H. J. (March 1999). "The Early Carboniferous (Courceyan–Arundian) monsoonal climate of the British Isles: evidence from growth rings in fossil woods". Geological Magazine. 136 (2): 177–187. doi:10.1017/S0016756899002307. ISSN 0016-7568.
  4. Sanz-López, Javier; Blanco-Ferrera, Silvia (1 October 2012). "Overgrowths of large authigenic apatite crystals on the surface of conodonts from Cantabrian limestones (Spain)". Facies. 58 (4): 707–726. doi:10.1007/s10347-012-0295-3. ISSN 1612-4820.
  5. Duffin, Christopher; Ward, David (1 January 1983). "Neoselachian sharks' teeth from the Lower Carboniferous of Britain and the Lower Permian of the USA". Palaeontology.
  6. Ginter, Michał; Duffin, Christopher; Dean, Mark; Korn, Dieter (2014). "Late Viséan pelagic chondrichthyans from northern Europe". Acta Palaeontologica Polonica. doi:10.4202/app.00084.2014.
  7. Cuny, Gilles (1 January 2008). "Carcharopsis prototypus and the adaptations of single crystallite enameloid in cutting dentitions". Acta Geologica Polonica.
  8. Duffin, Christopher J.; Ward, David J. (19 July 2017). "A new janassid petalodont chondrichthyan from the Early Carboniferous of Derbyshire, UK". Proceedings of the Geologists' Association. 128 (5–6): 809–814. doi:10.1016/j.pgeola.2017.06.008.
  9. Duffin, C. (1985). "Revision of the hybodont selachian genus Lissodus BROUGH (1935)". Palaeontographica Abteilung A-palaozoologie-stratigraphie. S2CID 233061921.
  10. Gutteridge, P. (May 1990). "The origin and significance of the distribution of shelly macrofauna in late Dinantian carbonate mud mounds of Derbyshire". Proceedings of the Yorkshire Geological Society. 48 (1): 23–32. doi:10.1144/pygs.48.1.23. ISSN 0044-0604.
  11. Tilsley, J. W. (December 1988). "New data on Carboniferous (Dinantian) trilobites from the Peak District, Derbyshire, England". Proceedings of the Yorkshire Geological Society. 47 (2): 163–176. doi:10.1144/pygs.47.2.163. ISSN 0044-0604.
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