Oxford Clay

The Oxford Clay (or Oxford Clay Formation) is a Jurassic marine sedimentary rock formation underlying much of southeast England, from as far west as Dorset and as far north as Yorkshire. The Oxford Clay Formation dates to the Jurassic, specifically, the Callovian and Oxfordian ages,[1] and comprises two main facies. The lower facies comprises the Peterborough Member, a fossiliferous organic-rich mudstone. This facies and its rocks are commonly known as lower Oxford Clay. The upper facies comprises the middle Oxford Clay, the Stewartby Member, and the upper Oxford Clay, the Weymouth Member. The upper facies is a fossil poor assemblage of calcareous mudstones.

Oxford Clay Stratigraphic range: Callovian to Oxfordian PreꞒ Ꞓ O S D C P T J K Pg N
Coastal exposure of the Oxford Clay Formation near Weymouth
Type	Geological formation
Unit of	Ancholme Group
Sub-units	Peterborough Member, Stewartby Member, Weymouth Member
Underlies	West Walton Formation, Corallian Group
Overlies	Kellaways Formation, Osgodby Formation
Thickness	Up to 185 metres, typically 50 to 70 m on East Midlands Shelf
Lithology
Primary	Claystone
Other	Mudstone
Location
Region	Oxford, Peterborough,  Dorset,  Yorkshire
Country	England
Type section
Named for	Oxford

Oxford Clay appears at the surface around Oxford, Peterborough and Weymouth and is exposed in many quarries around these areas. The top of the Lower Oxford Clay shows a lithological change, where fissile shale changes to grey mudstone. The Middle and Upper Oxford Clays differ slightly, as they are separated by an argillaceous limestone in the South Midlands.

Equivalent Callovo-Oxfordian Clay units like the Marnes de Dives also occur in the Paris Basin (France) and it is a potential host to dispose of high-level radioactive waste in France.

Palaeontology

The Oxford Clay is well known for its rich fossil record of fish and invertebrates.[2] Many of the fossils are well preserved, occasionally some are found exceptionally well preserved. Animals which lived in the Oxford Clay Sea include plesiosaurs, marine crocodiles, ichthyosaurs, cephalopods (such as belemnites), bivalves (such as Gryphaea), and a variety of gastropods. Dinosaur eggs are stratigraphically present in the Lower Oxford Clay. Geographically, they are located in Cambridgeshire, England.[3]

Ornithischians

Indeterminate euronithopod remains stratigraphically present in the Lower Oxford Clay and geographically located in Cambridgeshire, England.[3]

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.

Ornithischians of the Oxford Clay
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Callovosaurus	C. leedsi[3]	Cambridgeshire[3]	Lower[3]	"Femur."[4]		Callovosaurus Lexovisaurus
Lexovisaurus[5]	L. durobivensis[6]	Cambridgeshire[3] Dorset[7]	Lower[6]
	Indeterminate[8]	Bedfordshire[9]
Loricatosaurus[3]	L. priscus[3]	Cambridgeshire[3]	Lower[3]
Sarcolestes[3]	S. leedsi[3]	Cambridgeshire[3]	Lower[3]	"Partial mandible."[10]

Saurischians

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.

Saurischians of the Oxford Clay
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Cetiosauriscus[3]	C. stewarti[3]	Cambridgeshire[3]	Lower[3]	"Rear half of a skeleton."[11]		Cetiosauriscus Eustreptospondylus Metriacanthosaurus
Eustreptospondylus[12]	E. oxoniensis[12]	Oxfordshire[12]	Upper[12]	Disarticulated skull and skeleton, with some referred limb elements.[13]
Sauropoda	Indeterminate[14]	Wiltshire[14] Cambridgeshire[3]			The caudal vertebrae from Cambridgeshire were mistakenly considered part of the syntypic series of "Ornithopsis" leedsi by Upchurch and Martin (2003).[15]
Theropoda	Indeterminate[12]	Oxfordshire[12]	Middle[12]
Metriacanthosaurus	M. parkeri	Weymouth	Upper

Plesiosaurs

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.

Genus	Species	Location	Member	Abundance	Notes	Images
Cryptocleidus	C. eurymerus				A cryptoclidid	Cryptoclidus Liopleurodon Muraenosaurus Pachycostasaurus Peloneustes Simolestes
	C. richardsoni				A cryptoclidid
Liopleurodon	L. ferox				A thalassophonean pliosaurid
	L. pachydeirus				A thalassophonean pliosaurid
Marmornectes	M. candrewi				A pliosaurid
Muraenosaurus	M. leedsi				A cryptoclidid
Pachycostasaurus	P. dawnii				A pliosaurid
Peloneustes	P. philarchus				A thalassophonean pliosaurid
Picrocleidus	P. beloclis				A cryptoclidid
"Pliosaurus"	"P." andrewsi				A thalassophonean pliosaurid; represents a new genus distinct from Pliosaurus
Simolestes	S. vorax				A thalassophonean pliosaurid
Tricleidus	T. seeleyi				A cryptoclidid

Pachycormiformes

|- | Leedsichthys || L. problematicus || |-

Thalattosuchians

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.

Genus	Species	Location	Member	Abundance	Notes	Images
Gracilineustes	G. leedsi				A metriorhynchine metriorhynchid	Metriorhynchus Steneosaurus Suchodus Tyrannoneustes
Lemmysuchus	L. obtusidens				A teleosaurid belonging to Machimosaurini
Metriorhynchus	M. superciliosus				A metriorhynchine metriorhynchid
Steneosaurus	S. durobrivensis				A teleosaurid
	S. edwardsi				A teleosaurid
	S. leedsi				A teleosaurid
Suchodus	S. brachyrhynchus				A geosaurine metriorhynchid
	S. durobrivensis				A geosaurine metriorhynchid
Tyrannoneustes[16]	T. lythrodectikos				A geosaurine metriorhynchid

Economic use

Oxford Clay has a porous consistency and is soft and is often used in the making of roads. It is also the source of the Fletton stock brick of which much of London is built. For brick making, the Oxford Clay has the advantage of containing carbon which provides part of the fuel required in firing it so reducing the requirement for an external fuel source.

See also

• List of fossil sites (with link directory)
• List of dinosaur-bearing rock formations
• Kimmeridge Clay
• London Clay
• Weald Clay

References

1. "Oxford Clay Formation". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 21 August 2017.
2. Martill, D.M.; Hudson J.D. (1991). Fossils of the Oxford Clay. Palaeontological Association.
3. "10.9 Cambridgeshire, England; 1. Lower Oxford Clay," in Weishampel, et al. (2004). Page 540.
4. "Table 18.1," in Weishampel, et al. (2004). Page 396.
5. Weishampel, et al. (2004). Pages 539-540.
6. "10.7 Dorset, England; 3. Lower Oxford Clay" and "cambridgeshire">"10.9 Cambridgeshire, England; 1. Lower Oxford Clay," in Weishampel, et al. (2004). Pages 539-540.
7. "10.7 Dorset, England; 3. Lower Oxford Clay," in Weishampel, et al. (2004). Page 539.
8. Listed as "?Lexovisaurus sp." in "10.10 Bedfordshire, England; 1. Oxford Clay," in Weishampel, et al. (2004). Page 540.
9. "10.10 Bedfordshire, England; 1. Oxford Clay," in Weishampel, et al. (2004). Page 540.
10. "Table 17.1," in Weishampel, et al. (2004). Page 367.
11. "Table 13.1," in Weishampel, et al. (2004). Page 265.
12. "10.14 Oxfordshire, England; 8. Middle Oxford Clay," in Weishampel, et al. (2004). Page 540.
13. "Table 4.1," in Weishampel, et al. (2004). Page 72.
14. "10.14 Wiltshire, England; 4. Oxford Clay," in Weishampel, et al. (2004). Page 540.
15. Noé LF, Liston JJ, Chapman SD. 2010. ‘Old bones, dry subject’: the dinosaurs and pterosaur collected by Alfred Nicholson Leeds of Peterborough, England. Geological Society, London, Special Publications 343: 49–77.
16. Mark T. Young; Marco Brandalise de Andrade; Stephen L. Brusatte; Manabu Sakamoto; Jeff Liston (2013). "The oldest known metriorhynchid super-predator: a new genus and species from the Middle Jurassic of England, with implications for serration and mandibular evolution in predacious clades". Journal of Systematic Palaeontology. 11 (4): 475–513. doi:10.1080/14772019.2012.704948.

Bibliography

• Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.

Further reading

• Andrews, C. W. 1910. "A Descriptive Catalogue of the Marine Reptiles of the Oxford Clay, Part I". British Museum (Natural History), London, England: 205 pp.
• Andrews, CW. 1913. A descriptive catalogue of the Marine Reptiles of the Oxford Clay, Part II. British Museum (Natural History). pp. 205pp.
• M. J. Benton and P. S. Spencer. 1995. Fossil Reptiles of Great Britain. Chapman & Hall, London 1-386
• J. B. Delair. 1973. The dinosaurs of Wiltshire. The Wiltshire Archaeological and Natural History Magazine 68:1-7
• P. M. Galton. 1980. European Jurassic ornithopod dinosaurs of the families Hypsilophodontidae and Camptosauridae. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 160(1):73-95
• D. M. Martill. 1988. A review of the terrestrial vertebrate of fossils of the Oxford Clay (Callovian-Oxfordian) of England. Mercian Geologist 11(3):171-190