The basin is located along southern half of the Isle of Wight and Purbeck, extending offshore into the English Channel.

The Wealden Group is not widely present elsewhere in Britain, as these areas were tectonic highs where little to no sediment deposition was taking place.

It has been exposed at the surface due to the creation of anticlinal structures as a distant effect of the formation of the Pyrenees as part of the Alpine Orogeny during the Paleogene.

[5] The major source rocks for the sediments were from the Cornubian Massif to the west, an upland region roughly equivalent to the extent of Cornwall and Devon, with occasional large dropstones transported in tree roots being found in Wealden sediments over 100 kilometres from where they originated.

[9] One notable persistent horizon within the Purbeck sections of the formation is the "Coarse Quartz Grit", an up to 6 metre thick sequence of conglomeratic ironstone, with many beds including numerous centimetre sized subangular to rounded pebbles predominantly of vein derived quartz, hence the name.

The primary lithology of the exposed portion of the formation on the Isle of Wight consists of featureless purple-red overbank mudstone, interbedded with sandstones.

[13] The climate at the time of deposition is considered to be semi-arid, based on the presence of pedogenic calcrete nodules within the mudstones.

These consist of a basal matrix supported conglomerate, grading upwards into grey mudstone with lignitic plant debris, including large trunk fragments of the extinct conifer Pseudofrenelopsis present in the upper portion.

[16] The debris beds do not form a continuous horizon throughout the formation, but are laterally extensive over tens of metres.

Many of the wood fragments in the debris beds are cemented together with large nodules of pyrite, suggesting depositional conditions were anoxic.

Just above the "Hypsilophodon bed" the red mudstones of the Wessex Formation change to the transitional light coloured sandstone "White rock" and overlying laminated grey mudstones of the Vectis Formation, caused by the changing of environmental conditions from that of a floodplain to coastal lagoon conditions.

[18] The palaeoenvironment of the Wessex Formation is considered to have been semi-arid, and has variously been compared to chaparral[13] or macchia[10] Mediterranean shrubland.

The dominant trees were conifers of the extinct family Cheirolepidiaceae belonging to the genera Pseudofrenelopsis and Watsoniocladus, both of which have reduced xerophytic leaves adapted to arid conditions.

Amber can be found present as a rare component in plant debris beds in the Wessex formation both on the Isle of Wight and the Isle of Purbeck, however, the only significant concentration and where all of the inclusions have been found is a lag channel in the L6 plant debris horizon just south-east of Chilton Chine.

Only four species from the amber have been formally described, Cretamygale chasei a mygalomorph spider, Dungeyella gavini[21] Libanodiamesa simpsoni, both chironomid midges, as well as Embolemopsis maryannae, a embolemid parasitic wasp.

Specimens classified as Iguanodon seelyi are referable to this species Mantellisaurus M. atherfieldensis Dollodon bampingi, Proplanicoxa?

"[43] A possible oviraptorosaur Ceratosuchops C. inferodios Partial skull material[44] A spinosaurid, formerly considered remains of Baryonyx.

Indeterminate Teeth Dubious, uncertain referral on the genus level Riparovenator R. milnerae Partial skull and referred caudal material[44] A spinosaurid, formerly considered remains of Baryonyx.