Wealden Group
Stratigraphic range: LateBerriasian-Aptian,140–125 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Coastal exposure of the Wealden Group nearBexhill-on-Sea
Type	Group
Sub-units	Weald Basin Weald Clay Formation Tunbridge Wells Sand Formation Wadhurst Clay Formation Ashdown Formation Wessex Basin Vectis Formation Wessex Formation Marginal -Whitchurch Sand Formation
Underlies	Lower Greensand Group
Overlies	Purbeck Group
Thickness	Up to 850 m in Weald Basin, c. 500 m in Wessex basin, few m in marginal areas
Location
Region	England
Country	UK
Type section
Named for	Weald

TheWealden Group, occasionally also referred to as theWealden Supergroup, is agroup (a sequence ofrock strata) in thelithostratigraphy of southernEngland. The Wealden group consists ofparalic tocontinental (freshwater)faciessedimentary rocks ofBerriasian toAptian age and thus forms part of the EnglishLower Cretaceous. It is composed of alternatingsands andclays. The sandy units were deposited in aflood plain ofbraided rivers, the clays mostly in alagoonalcoastal plain.^[1]

The Wealden Group can be found in almost all Early Cretaceousbasins of England: its outcrops curve from theWessex Basin in the south to theCleveland Basin in the northeast. It is not found in northwest England andWales, areas which were at the timetectonic highs where no deposition took place. The same is true for theLondon Platform around London andEssex. Offshore, the Wealden Group can reach a thickness of 700 metres.^[1] The termsWealden andWealdenfacies are also used as generic terms referring to Early Cretaceous non-marine sequences elsewhere in Europe.

The Wealden Group liesstratigraphically on top of thePurbeck Group, which spans theJurassic-Cretaceous boundary. Within theWessex Basin, the Wealden Group consists of twoformations: theWessex Formation and overlyingVectis Formation. In theWeald Basin, the Wealden Group consists of four formations: theAshdown Formation, theWadhurst Clay Formation, theTunbridge Wells Sand Formation and theWeald Clay Formation.^[2] The lower three formations are sometimes collectively referred to as theHastings Beds. InOxfordshire,Buckinghamshire andWiltshire, the Wealden Group is only found as anoutlier on top of hills and only consists of a single formation, theWhitchurch Sand Formation. In Yorkshire, the equivalently agedSpeeton Clay Formation, a marine unit, is present.

On top of the Wealden Group is theLower Greensand Group. The difference between these two groups has been formed by a majoreustatic (global)transgression of the sea. The Greensand (Aptian/Albian in age) consists of marine deposits.

The sequence in the Weald Basin has also been described as asupergroup, containing the Weald Clay Group and Hastings Group.^[3]

The Wealden Group formsoutcrops covering a large part of south and south-easternEngland including theIsle of Wight. It takes its name from theWeald region ofKent,Sussex,Surrey andHampshire. It has yielded many fossils, includingdinosaurs likeIguanodon andHypsilophodon.^[4] Apart from fossils, it shows many other signs of being deposited in a continental environment, such asmudcracks and -in some rare cases- dinosaur footprints. Taxa included in the table below have an uncertain provenance and cannot be placed into one of the constituent formations, thus they are placed here.

Pterosaurs reported from the Wealden Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Coloborhynchus	C. clavirostris[5]	St.-Leonards-on-Sea[5]	Hastings Beds	"Anterior portion of rostrum"[5]	Anornithocheirid pterosaur.

Dinosaurs reported from the Wealden Group
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Thecospondylus[6]	T. horneri[6]	Kent[6]	Hastings Beds	"Internal mold of sacrum."[7]	Dubious genus that has been variously classified as either a saurischian or ornithischian.[8] It is currently only tentatively regarded as dinosaurian.[6]
Therosaurus[9]	T. anglicus[9]	West Sussex[9]
Altispinax[10]	A. dunkeri[10]	East Sussex[10]	Hastings Beds	"Dorsal vertebrae."[11]
Haestasaurus[12]	H. becklesii[10]	East Sussex[10]	Hastings Beds	Forelimb	A ?basalmacronarian
Pleurocoelus[13]	P. valdensis[13]	East Sussex[10] West Sussex[9]			A dubious basal titanosauriform[13]
Turiasauria	Indeterminate		Hasting beds?[14]	Vertebra[14]
Theropoda	Indeterminate	West Sussex, East Sussex, Kent[15]
Xenoposeidon	X. proneneukos				Arebbachisauridsauropod

The term "Wealden" and "Wealden facies" has been applied to other Lower Cretaceous sequences in Europe, including the "German Wealden", comprising theBerriasian agedBückeberg Formation of the Lower Saxony Basin^[16] and in Belgium, where "Wealden facies" has been used as a term to refer to the Barremian-Aptian aged sequences of the Mons Basin, including theSainte-Barbe Clays Formation where large numbers ofIguanodon were found in the 19th century.^[17]

• List of dinosaur-bearing rock formations

• Geological groups of the United Kingdom
• Geologic formations of England
• Lithostratigraphy of England
• Lower Cretaceous Series of Europe
• Cretaceous England
• Berriasian Stage
• Valanginian Stage
• Hauterivian Stage
• Barremian Stage
• Aptian Stage
• Shale formations
• Sandstone formations

• Articles with short description
• Short description is different from Wikidata
• Use dmy dates from April 2022