Wessex Formation

Wessex Formation
Stratigraphic range: Berriasian–Barremian PreꞒ Ꞓ O S D C P T J K Pg N
Exposure of the Wessex Formation west of Chilton Chine
Type	Geological formation
Unit of	Wealden Group
Sub-units	Coarse Quartz Grit (in Dorset)
Underlies	Vectis Formation
Overlies	Durlston Formation
Thickness	up to 1000 m near Swanage
Lithology
Primary	mudstone
Other	sandstone, ironstone & conglomerate
Location
Region	Southern England
Country	UK
Extent	Dorset, Isle of Wight, offshore Wessex Basin
Type section
Named for	Wessex
Named by	Daley and Stewart
Location	Bacon Hole, Mupe Bay
Year defined	1979
Exposure of the Wessex and Vectis Formations on the South Coast of the Isle of Wight, shown in turquoise.

The Wessex Formation is a fossil-rich English geological formation that dates from the Berriasian to Barremian stages of the Early Cretaceous. It forms part of the Wealden Group and underlies the younger Vectis Formation and overlies the Durlston Formation.^[1] The dominant lithology of this unit is mudstone with some interbedded sandstones. It is part of the strata of the Wessex Basin, exposed in both the Isle of Purbeck and the Isle of Wight. While the Purbeck sections are largely barren of vertebrate remains, the Isle of Wight sections are well known for producing the richest and most diverse fauna in Early Cretaceous Europe.