Weald Clay

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Weald Clay
Stratigraphic range: Hauterivian-Barremian, 136–125 Ma
TypeGeological formation
Unit ofWealden Group
Sub-unitsHorsham Stone Member
UnderliesAtherfield Clay Formation
OverliesTunbridge Wells Sand Formation
Thicknessup to 460 m
PrimaryShale, Mudstone
OtherSiltstone, Sandstone, Limestone, Ironstone
Country UK

Weald Clay or the Weald Clay Formation is a Lower Cretaceous sedimentary rock underlying areas of South East England. It is part of the Wealden Group of rocks.[1] The clay is named after the Weald, an area of Sussex and Kent. It varies from orange and grey in colour and is used in brickmaking.

The un-weathered form is blue/grey, and the yellow/orange is the weathered form; they have quite 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.


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


B. walkeri

Multiple partial skulls, one of which had an associated postcranial skeleton.[2]


H. rudgwickensis

"Vertebrae, partial fore and hindlimbs, osteoderms."[3]

An ankylosaur belonging to Polacanthinae. Originally named as a species of Polacanthus.[4]


P. rudgwickensis

Rudgwick Brickworks

Upper Weald Clay

Single partial fore-wing

An Ithonidae lacewing, the second in Principiala


V. canaliculatus[6]

An iguanodontian

Leptocleidus L. superstes[7] NHM R4828 (holotype) Pliosauroid

See also[edit]


  1. ^ "Wealden Clay Formation". The BGS Lexicon of Named Rock Units. British Geological Survey. Retrieved 14 December 2014.
  2. ^ "Table 4.1," in Weishampel, et al. (2004). Page 72.
  3. ^ "Table 17.1," in Weishampel, et al. (2004). Page 367.
  4. ^ 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.
  5. ^ Jepson, JE; Makarkin, VN; Jarzembowski, E (2009). "New lacewings (Insecta: Neuroptera) from the Lower Cretaceous Wealden supergroup of Southern England". Cretaceous Research. 30: 1325–1338. doi:10.1016/j.cretres.2009.07.012.
  6. ^ 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
  7. ^ "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 2017-11-16.


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