Weald Clay

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Template:Short description Template:Use dmy dates Script error: No such module "Infobox".Template:Template otherScript error: No such module "check for unknown parameters". Weald Clay or the Weald Clay Formation is a Lower Cretaceous sedimentary rock unit underlying areas of South East England, between the North and South Downs, in an area called the Weald Basin. It is the uppermost unit of the Wealden Group of rocks within the Weald Basin, and the upper portion of the unit is equivalent in age to the exposed portion of the Wessex Formation on the Isle of Wight. It predominantly consists of thinly bedded mudstone.[1] The un-weathered form is blue/grey, and the yellow/orange is the weathered form, it is used in brickmaking.

The formation was deposited in lagoonal, lacustrine and alluvial conditions that varied from freshwater to brackish.[2] The climate at the time of deposition is thought to have been semi-arid,[3] and prone to fire.[4] The clay alternates with other subordinate lithologies, notably hard red-weathering beds of ironstone, limestone (Sussex Marble) and sandstones, notably including the calcareous sandstone unit referred to as the Horsham Stone. It has a gradual, conformable contact with the underlying Tunbridge Wells Sand Formation, and has a sharp, unconformable contact with the overlying Atherfield Clay Formation, a shallow marine unit deposited after marine transgression during the Aptian.

Physical properties

File:Weald Clay Cooden Beach.jpg
Bored exposure of the lower Weald Clay on the shore near Cooden Beach

The weathered and unweathered forms of the Weald Clay have different physical properties. Blue looks superficially like a soft slate, is quite dry and hard and will support the weight of buildings quite easily. Because it is quite impermeable, and so dry, it does not get broken by tree roots. It is typically found at 750mm down below a layer of yellow clay. Yellow, found on the surface, absorbs water quite readily so becomes very soft in the winter. The two different types make quite different bricks.

Paleofauna

Vertebrates

Vertebrates reported from the Weald Clay
Genus Species Location Stratigraphic position Material Notes Images

Baryonyx

B. walkeri

Smokejack Clay Pit Upper Weald Clay

Multiple partial skulls, one of which had an associated postcranial skeleton.[5]

A spinosaurid
File:Baryonyx walkeri restoration.jpg
Baryonyx

Horshamosaurus

H. rudgwickensis

Rudgwick Brickworks Upper Weald Clay

"Vertebrae, partial fore and hindlimbs, osteoderms."[6]

A dubious[7] genus of nodosaurid ankylosaur belonging to Polacanthinae. Originally named as a species of Polacanthus.[8]

Iguanodon I. bernissartensis Smokejack Clay Pit Upper Weald Clay Iguanodontian, also known from the Wessex Formation.
File:Iguanodon new NT.jpg
Iguanodon
Mantellisaurus M. atherfieldensis Smokejack Clay Pit Upper Weald Clay Iguanodontian, also known from the Wessex Formation
File:Mantellisaurus atherfieldensis Steveoc.jpg
Mantellisaurus

Valdosaurus

V. canaliculatus[9]

Heathfield Lower Weald Clay

A dryosaurid, also known from the Wessex Formation

Leptocleidus L. superstes[10] NHM R4828 (holotype) Pliosauroid
File:Leptocleidus1DB.jpg
Leptocleidus
Wyleyia[11] W. valdensis[11]
Dorsetisaurus Indeterminate Keymer Tile Works
Sauropoda Indeterminate Smokejacks, Bexhill
Anura Indeterminate Keymer Tile Works Lower Maxillary fragment[12]
Urodela Indeterminate Keymer Tile Works Lower Atlas vertebra Has been suggested to have a close relationship with Balveherpeton from Germany.[13]

Invertebrates

Numerous insect species are known from several localities in the Weald Clay, including Rudgwick Brickworks,[14] Auclaye Brickworks,[15] Smokejacks[16] and Clockhouse Brickworks[17][18][19]

Invertebrates reported from the Weald Clay
Genus Species Location Stratigraphic position Material Notes Images
Principiala[20] P. rudgwickensis Rudgwick Brickworks Upper Weald Clay Single partial fore-wing An Ithonidae lacewing, the second in Principiala
Englathauma E. crabbi Rudgwick Brickworks BMB 021962/3 almost complete forewing A englathaumatid scorpionfly
E. mellishae Smokejacks Wing and wing fragments
Cretophasmomima[21] C. traceyae Smokejacks Forewing A stick insect
Valdicossus V. mikewebsteri[22] Smokejacks Upper Hindwing A member of Palaeontinidae
V. chesteri[23] Cooden Beach Lower Hindwing
Ilerdocossus I. prowsei [22] Clockhouse Brickworks Lower A member of Palaeontinidae
Proraphidia P. hopkinsi[24] A member of Mesoraphidiidae
Turanophlebia T. anglicana[25] Dragonfly, member of Tarsophlebiidae
Brochocoleus B. keenani[26] B. tobini Smokejacks Upper Member of Ommatidae
Diluticupes D. crowsonae
Zygadenia Z. tuberculata,[27] Z. angliae[28]
Cionocoleus C. elizabethae, C. watsoni [29] C. minimus
Omma O. elongatum Keymer Tile Works Lower

Flora

Plants reported from the Weald Clay
Genus Species Location Stratigraphic position Material Notes Images
Weichselia[4] W. reticulata A tree fern
Brachyphyllum[4] Conifer leaves
Pagiophyllum[4] Conifer leaves
Pseudofrenelopsis[4] P. parceramosa A conifer belonging to the extinct family Cheirolepidiaceae

See also

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Footnotes

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  5. ↑ "Table 4.1," in Weishampel, et al. (2004). Page 72.
  6. ↑ "Table 17.1," in Weishampel, et al. (2004). Page 367.
  7. ↑ Raven, T. J., P. M. Barrett, S. B. Pond, and S. C. R. Maidment. 2020. Osteology and taxonomy of British Wealden Supergroup (Berriasian–Aptian) ankylosaurs (Ornithischia, Ankylosauria). Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2020.1826956
  8. ↑ Blows, W.T., 2015, British Polacanthid Dinosaurs – Observations on the History and Palaeontology of the UK Polacanthid Armoured Dinosaurs and their Relatives, Siri Scientific Press, 220 pp.
  9. ↑ Galton, P.M., 2009, "Notes on Neocomian (Late Cretaceous) ornithopod dinosaurs from England - Hypsilophodon, Valdosaurus, "Camptosaurus", "Iguanodon" - and referred specimens from Romania and elsewhere", Revue de Paléobiologie 28(1): 211-273
  10. ↑ Script error: No such module "citation/CS1".
  11. ↑ a b c "10.18 West Sussex, England; 1. Hastings Beds" in Weishampel, et al. (2004). Page 559.
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  24. ↑ J. E. Jepson and E. A. Jarzembowski. 2008. Two new species of snakefly (Insecta: Raphidioptera) from the Lower Cretaceous of England and Spain with a review of other fossil raphidiopterans from the Jurassic/Cretaceous transition. Alavesia 2:193-201
  25. ↑ G. Fleck, G. Bechly, X. Martínez-Delclòs, E. A. Jarzembowski, and A. Nel. 2004. A revision of the Upper Jurassic-Lower Cretaceous dragonfly family Tarsophlebiidae, with a discussion on the phylogenetic positions of the Tarsophlebiidae and Sieblosiidae (Insecta, Odonatoptera, Panodonata. Geodiversitas 26(1):33-59
  26. ↑ Script error: No such module "Citation/CS1".
  27. ↑ Script error: No such module "Citation/CS1".
  28. ↑ A. G. Ponomarenko. 2006. On the Types of Mesozoic Archostematan Beetles (Insecta, Coleoptera, Archostemata) in the Natural History Museum, London. Paleontological Journal 40(1):90-9
  29. ↑ E. A. Jarzembowski, E. V. Yan, B. Wang and H. Zhang. 2013. Ommatin beetles (Insecta: Coleoptera) from the Lower Cretaceous of northeast China and southern England. Terrestrial Arthropod Reviews 6:135-161

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References

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