Wadhurst Clay Formation
Wadhurst Clay Formation | |
---|---|
Stratigraphic range: | |
Type | Geological formation |
Unit of | Wealden Group |
Underlies | Tunbridge Wells Sand Formation |
Overlies | Ashdown Formation |
Thickness | 30 to 78 m |
Lithology | |
Primary | Shale, Mudstone |
Other | Siltstone, Sandstone, Limestone, Ironstone |
Location | |
Region | Europe |
Country | UK |
Extent | Weald Basin |
Type section | |
Named for | Wadhurst |
The Wadhurst Clay Formation is a geological unit which forms part of the
.The other component formations of the
Lithology
The Wadhurst Clay comprises predominantly medium to dark bluish grey over-consolidated clays, silts, mudstones, and shales. These lithologies often occur with subordinate amounts of pale grey silty mudstones, laminated siltstones, sandstones, conglomerate, shelly limestones and clay-ironstones.[2] When they become exposed to the elements at the surface, the mudstones often degrade over a short period of time and weather to yellowish brown and greenish grey clays.[3]
The formation thickness ranges from 55m in the
The base of the Wadhurst Clay is taken at the bottom of the Top Ashdown Pebble Bed. The base of this marker horizon marks the formational change to the Ashdown Formation. Despite its name this thin and impressistent bed comprises a coarse grained to gravelly sandstone. This horizon is best exposed at Cliff End, East Sussex, but where it is encountered elsewhere, it is usually fairly distinctive and easily identified. The Top Ashdown Pebble Bed occurs mainly in the southern half of East Sussex and is often missing elsewhere. Where this is the case, the boundary is taken at a layer of disconnected ripples.[5]
The top of the Wadhurst Clay is marked by a distinct lithological change into the siltstones of the Tunbridge Wells Sand Formation. The uppermost clays of the Wadhurst Clay, closest to the boundary are often stained red.[1]
Engineering Geology
Natural slopes in the Wadhurst Clay, like those in the
Landslips often occur at or close to the upper boundary of the Wadhurst Clay, which is shared with the overlying
When percolating groundwater in the permeable sandstones of the
Paleobiota
Taken from [6]
Fish
Fish reported from the Wadhurst Clay | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Egertonodus | E. basanus | Ashdown Brickworks[7] | Hybodont shark
|
|||
Planohybodus | P. ensis | |||||
Polyacrodus | P. parvidens, P. brevicostatus | |||||
Ocloedus | Pycnodontiform | |||||
Coccolepis | Coccolepidid[8] | |||||
Semionotiformes, | ||||||
Albuliformes
|
Dinosaurs
Dinosaurs reported from the Wadhurst Clay | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
"Megalosaurus" | M. dunkeri | Hollington Quarry | Tooth | An indeterminate theropod which was mistakenly identified with Altispinax dunkeri. | ||
Barilium | B. dawsoni[9] | Shornden Quarry, Old Roar Quarry, | "[Two] partial skeletons."[10] | An iguanodontian | ||
Hypselospinus | H. fittoni[9] | Hollington Quarry, Shornden Quarry, Hare Farm Lane, Brede | Partial skeletons | An iguanodontian | ||
Suchosaurus | S. cultridens | Hare Farm Lane, Brede | Teeth | A spinosaurid | ||
Unnamed maniraptoran | Indeterminate | Ashdown Brickworks | Specimen BEXHM: 2008.14.1[11] A single cervical vertebra | Possibly an oviraptorosaur[11]
|
Amphibians
Amphibians reported from the Wadhurst Clay | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Anura | Indeterminate | Ashdown Brickworks | Two fragmentary ilia | At least 2 taxa[12] | ||
Urodela | Indeterminate | Atlas and postatlas vertebrae, dentary, maxilla and vomer fragments | At least 3 taxa distinguishable by their atlas vertebrae[12] |
Crocodyliformes
Crocodyliformes reported from the Wadhurst Clay | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Goniopholis | G. crassidens | Hare Farm Lane, Brede | A Goniopholid Neosuchian. | |||
Hulkepholis | Indeterminate | Ashdown Brickworks[7] | A goniopholid | |||
Theriosuchus | An atoposaurid | |||||
Bernissartiidae |
Mammals
Mammals reported from the Wadhurst Clay | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Laolestes | L. hodsoni | Cliff End bonebed, Tighe Farm | Cypridea paulsgrovensis ostracod Zone | Dryolestid | ||
Spalacotherium | S. tricuspidens | Cliff End bonebed | Spalacotheriid | |||
Aegialodon | A. dawsoni | Cladotherian | ||||
Loxaulax | L. valdensis | Eobataarid multituberculate |
Plesiosaurians
Plesiosaurians reported from the Wadhurst Clay | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
Hastanectes | H. valdensis | Old Roar Quarry, Hollington Quarry, Black Horse Quarry, Hastings, Brenchley |
Pterosaurs
Pterosaurs reported from the Wadhurst Clay Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
? Istiodactylidae indet. | Indeterminate | Cliff End Bone Bed, Cliff End.[13] | 2 isolated tooth crowns (BEXHM: 2022.109.1 & BEXHM: 2022.109.2).[13] | An istiodactylid. |
See also
References
- ^ a b Hopson, P.M., Wilkinson, I.P. and Woods, M.A. (2010) A stratigraphical framework for the Lower Cretaceous of England. Research Report RR/08/03. British Geological Survey, Keyworth.
- ^ a b Lake, R.D. & Shepard-Thorn, E.R. (1987) Geology of the country around Hastings and Dungeness: Memoir for 1:50,000 geological sheets 320 and 321. British Geological Survey, London.
- ^ a b c Codd, J.W. (2007) Analysis of the distribution and characteristics of landslips in the Weald of East Sussex. MSc dissertation, University of Brighton.
- ^ Reeves, G.M., Sims, I., & Cripps, J.C. (2006) Clay Minerals Used in Construction, Geological Society, London, Engineering Geology Special Publication, 21, 153-175.
- ^ Lake, Shepard-Thorn, E.R., Smart, J.G.O., Bisson, G. & Edmonds, E.A. (1966) Geology of the country around Tenterden: Memoir for 1:50,000 geological sheet 304. British Geological Survey, London.
- ^ "Wadhurst Clay Formation". Paleobiology Database.
- ^ S2CID 202904040.
- ^ Peter and Joyce Austen Wealden fish (2011) โ Based on a talk given by Peter Forey (Natural History Museum)
- ^ a b "10.19 East Sussex, England; 1. Hastings Beds" in Weishampel, et al. (2004). Page 559.
- ^ "Table 19.1," in Weishampel, et al. (2004). Page 416.
- ^
- ^ )
- ^ ISSN 0195-6671.