The Wealden Group, occasionally also referred to as the Wealden Supergroup, is a group in the lithostratigraphy of southern England. The Wealden group consists of paralic to continental (freshwater) facies sedimentary rocks of Berriasian to Aptian age and thus forms part of the English Lower Cretaceous. It is composed of alternating sands and clays. The sandy units were deposited in a flood plain of braided rivers, the clays mostly in a lagoonal coastal plain.
Coastal exposure of the Wealden Group near Bexhill-on-Sea
Coloborhynchus
Image: Thecospondylus
Image: Becklespinax
The Purbeck Group is an Upper Jurassic to Lower Cretaceous lithostratigraphic group in south-east England. The name is derived from the district known as the Isle of Purbeck in Dorset where the strata are exposed in the cliffs west of Swanage.
Strata of the Purbeck Group in Durlston Bay, Dorset
Gastropods and bivalves in the Portland limestone, Purbeck quarry, southern England. Scale of the large gastropod is about 5 centimetres (2.0 in).
Animals by the Purbeck lagoon
Thrombolites in the basal part of the Purbeck Group, Isle of Portland