Lambeth Group

Lambeth Group
Stratigraphic range: Thanetian-Ypresian
Exposure in Gilbert's Pit. Dark grey clays, and light grey shelly clays of the Woolwich Formation overlying yellow-brown weathering sands of the Upnor Formation
Type	Group
Sub-units	Upnor Formation, Reading Formation, Woolwich Formation
Underlies	Thames Group
Overlies	Thanet Sand, Chalk Group
Thickness	Up to 39 m
Lithology
Primary	Clay
Other	Sand, Gravel, Limestone, Lignite, Sandstone, Conglomerate
Location
Region	southern England
Country	UK
Extent	London Basin and Hampshire Basin

The Lambeth Group is a stratigraphic group, a set of geological rock strata in the London and Hampshire Basins of southern England. It comprises a complex of vertically and laterally varying gravels, sands, silts and clays deposited between 56-55 million years before present during the Ypresian age (lower Eocene). It is found throughout the London Basin with a thickness between 10m and 30m, and the Hampshire Basin with a thickness between 50m and less than 25m. Although this sequence only crops out in these basins, the fact that it underlies 25% of London at a depth of less than 30m means the formation is of engineering interest for tunnelling and foundations.