Weald Clay

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Weald Clay
Stratigraphic range: Hauterivian-Barremian, 136–125  Ma
Clay Pit, Clock House, near Capel - geograph.org.uk - 1779315.jpg
Weald Clay exposed at Clock House Brickworks
Type Geological formation
Unit of Wealden Group
Sub-unitsHorsham Stone Member
Underlies Atherfield Clay Formation
Overlies Tunbridge Wells Sand Formation
Thicknessup to 460 m
Lithology
Primary Shale, Mudstone
Other Siltstone, Sandstone, Limestone, Ironstone
Location
Region England
CountryUnited Kingdom
Type section
Named for Weald
Gallois Geological Map of Wealden District 1965.jpg
Extent of the Weald Clay within the Weald Basin, shown with horizontal lines

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.

Contents

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

Bored exposure of the lower Weald Clay on the shore near Cooden Beach 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
GenusSpeciesLocationStratigraphic positionMaterialNotesImages

Baryonyx

B. walkeri

Smokejack Clay Pit Upper Weald Clay

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

A spinosaurid
Baryonyx Baryonyx walkeri restoration.jpg
Baryonyx

Horshamosaurus

H. rudgwickensis

Rudgwick BrickworksUpper 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. bernissartensisSmokejack Clay PitUpper Weald ClayIguanodontian, also known from the Wessex Formation.
Iguanodon Iguanodon new NT.jpg
Iguanodon
Mantellisaurus M. atherfieldensisSmokejack Clay PitUpper Weald ClayIguanodontian, also known from the Wessex Formation
Mantellisaurus Mantellisaurus atherfieldensis Steveoc.jpg
Mantellisaurus

Valdosaurus

V. canaliculatus [9]

HeathfieldLower Weald Clay

A dryosaurid, also known from the Wessex Formation

Leptocleidus L. superstes [10] NHM R4828 (holotype)Pliosauroid
Leptocleidus Leptocleidus1DB.jpg
Leptocleidus
Wyleyia [11] W. valdensis [11]
Dorsetisaurus IndeterminateKeymer Tile Works
Sauropoda IndeterminateSmokejacks, Bexhill
Anura IndeterminateKeymer Tile WorksLowerMaxillary fragment [12]
Urodela IndeterminateKeymer Tile WorksLower 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
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Principiala [20] P. rudgwickensisRudgwick BrickworksUpper Weald ClaySingle partial fore-wingAn Ithonidae lacewing, the second in Principiala
Englathauma E. crabbiRudgwick BrickworksBMB 021962/3 almost complete forewingA englathaumatid scorpionfly
E. mellishaeSmokejacksWing and wing fragments
Cretophasmomima [21] C. traceyaeSmokejacksForewingA stick insect
Valdicossus V. mikewebsteri [22] SmokejacksUpperHindwingA member of Palaeontinidae
V. chesteri [23] Cooden BeachLowerHindwing
Ilerdocossus I. prowsei [22] Clockhouse BrickworksLowerA member of Palaeontinidae
Proraphidia P. hopkinsi [24] A member of Mesoraphidiidae
Turanophlebia T. anglicana [25] Dragonfly, member of Tarsophlebiidae
Brochocoleus B. keenani [26] B. tobiniSmokejacksUpperMember of Ommatidae
Diluticupes D. crowsonae
Zygadenia Z. tuberculata, [27] Z. angliae [28]
Cionocoleus C. elizabethae, C. watsoni [29] C. minimus
Omma O. elongatumKeymer Tile WorksLower

Flora

Plants reported from the Weald Clay
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Weichselia [4] W. reticulataA tree fern
Brachyphyllum [4] Conifer leaves
Pagiophyllum [4] Conifer leaves
Pseudofrenelopsis [4] P. parceramosaA conifer belonging to the extinct family Cheirolepidiaceae

See also

Footnotes

  1. "Wealden Clay Formation". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 14 December 2014.
  2. Radley, Jonathan D (June 1999). "Weald Clay (Lower Cretaceous) palaeoenvironments in south-east England: molluscan evidence". Cretaceous Research. 20 (3): 365–368. doi:10.1006/cres.1999.0156.
  3. Akinlotan, Oladapo O.; Moghalu, Ogechukwu A.; Hatter, Stuart J.; Okunuwadje, Sunday; Anquilano, Lorna; Onwukwe, Uche; Haghani, Safiyeh; Anyiam, Okwudiri A.; Jolly, Byami A. (July 2022). "Clay mineral formation and transformation in non-marine environments and implications for Early Cretaceous palaeoclimatic evolution: The Weald Basin, Southeast England". Journal of Palaeogeography. 11 (3): 387–409. doi:10.1016/j.jop.2022.04.002.
  4. 1 2 3 4 5 Batten, David J. (June 1998). "Palaeonenvironmental implications of plant, insect and other organic-walled microfossils in the Weald Clay Formation (Lower Cretaceous) of southeast England" . Cretaceous Research. 19 (3–4): 279–315. doi:10.1006/cres.1998.0116.
  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 Paléobiologie28(1): 211-273
  10. "Reassessment of the Lower Cretaceous (Barremian) pliosauroid Leptocleidus superstes Andrews, 1922 and other plesiosaur remains from the nonmarine Wealden succession of southern England | Oxford Academic". academic.oup.com. Retrieved 16 November 2017.
  11. 1 2 3 "10.18 West Sussex, England; 1. Hastings Beds" in Weishampel, et al. (2004). Page 559.
  12. Sweetman, S.C; Evans, S. E. (2011). "Lissamphibians (frogs, salamanders and albanerpetontids)". English Wealden fossils. Palaeontological Association. ISBN   978-1-4443-6711-9. OCLC   777385514.{{cite book}}: CS1 maint: multiple names: authors list (link)
  13. Skutschas, Pavel P.; Kolchanov, Veniamin V.; Schwermann, Achim H. (December 2020). "First salamander from the Lower Cretaceous of Germany" . Cretaceous Research. 116: 104606. doi:10.1016/j.cretres.2020.104606. S2CID   225440583.
  14. "Rudgwick Brickworks, Upper Weald Clay (Cretaceous of the United Kingdom)". fossilworks.org. Retrieved 17 December 2021.
  15. "Auclaye Brickworks (BMB collection) (Cretaceous of the United Kingdom)". Paleobiology Database . Retrieved 26 January 2020.
  16. "Smokejacks Brickworks (Cretaceous of the United Kingdom)". Paleobiology Database . Retrieved 26 January 2020.
  17. "Clockhouse Brickworks (MNEMG collection) (Cretaceous of the United Kingdom)". fossilworks.org. Retrieved 17 December 2021.
  18. "Clockhouse Brickworks (BMNH collection) (Cretaceous of the United Kingdom)". fossilworks.org. Retrieved 17 December 2021.
  19. "Clockhouse Brickworks (BMB collection): Late/Upper Hauterivian, United Kingdom". Paleobiology Database . Retrieved 26 January 2020.
  20. Jepson, JE; Makarkin, VN; Jarzembowski, E (2009). "New lacewings (Insecta: Neuroptera) from the Lower Cretaceous Wealden supergroup of Southern England". Cretaceous Research. 30 (5): 1325–1338. doi:10.1016/j.cretres.2009.07.012.
  21. Xu, Chunpeng; Jarzembowski, Edmund A.; Fang, Yan (January 2020). "A new stick insect (Phasmatodea: Susumanioidea) from the Lower Cretaceous Wealden Group of southern England". Cretaceous Research. 112: 104387. doi:10.1016/j.cretres.2020.104387. S2CID   214327966.
  22. 1 2 Li, Yuling; Jarzembowski, Edmund; Chen, Jun; Wang, Bo (March 2019). "New Palaeontinidae (Insecta: Hemiptera) from the Lower Cretaceous of southern England". Cretaceous Research. 95: 297–301. doi:10.1016/j.cretres.2018.11.019. S2CID   134479224.
  23. WANG, BO; ZHANG, HAICHUN; JARZEMBOWSKI, EDMUND A. (16 April 2008). "A new genus and species of Palaeontinidae (Insecta: Hemiptera: Cicadomorpha) from the Lower Cretaceous of southern England". Zootaxa. 1751 (1): 65. doi:10.11646/zootaxa.1751.1.7. ISSN   1175-5334.
  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. Alavesia2:193-201
  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. Geodiversitas26(1):33-59
  26. Jarzembowski, Edmund A.; Yan, Evgeny V.; Wang, Bo; Zhang, Haichun (August 2013). "Brochocolein beetles (Insecta: Coleoptera) from the Lower Cretaceous of northeast China and southern England". Cretaceous Research. 44: 1–11. doi:10.1016/j.cretres.2013.03.003. ISSN   0195-6671.
  27. Jarzembowski, Edmund A.; Wang, Bo; Zhang, Haichun; Fang, Yan (January 2015). "Boring beetles are not necessarily dull: New notocupedins (Insecta: Coleoptera) from the Mesozoic of Eurasia and East Gondwana". Cretaceous Research. 52: 431–439. doi:10.1016/j.cretres.2014.03.006. ISSN   0195-6671.
  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

References