Lower Greensand/Lias Group separation map

Area where aquifer and shale/clay are present	South Lincolnshire Norfolk to Dorset around the Weald
Thickness of intervening strata	South Lincolnshire: about 400 to 500 m Norfolk: up to about 260 m, decreasing south and eastwards to about 40 to 100 m in Cambridgeshire and Bedfordshire Southern England including Oxfordshire and Buckinghamshire: up to 2000 m, thickest around the Weald and Isle of Wight
Lithology of intervening strata	South Lincolnshire: permeable Great Oolite Group and Inferior Oolite Group (principal aquifer); low permeability Kellaways Formation (clay); low permeability Oxford Clay Formation (clay); low permeability Osgodby Formation (clay); low permeability Kimmeridge Clay Formation (clay); low permeability Ampthill Clay Formation (clay); permeable Spilsby Sandstone Formation (principal aquifer); permeable Wealden Group sandstone; low permeability Wealden Group limestone Norfolk: Great Oolite Group and Inferior Oolite Group (principal aquifer); low permeability Kellaways Formation (clay); low permeability Oxford Clay Formation (clay); low permeability Osgodby Formation (clay); low permeability Kimmeridge Clay Formation (clay); low permeability Ampthill Clay Formation (clay); permeable Wealden Group sandstone Southern England including Oxfordshire and Buckinghamshire: Great Oolite Group and Inferior Oolite Group (principal aquifer); low permeability Kellaways Formation (clay); low permeability Oxford Clay Formation (clay); low permeability Osgodby Formation (clay); permeable Corallian Group (principal aquifer); low permeability Kimmeridge Clay Formation (clay); low permeability Ampthill Clay Formation (clay); permeable Portland Group; permeable Purbeck Group; low permeability Wealden Group
Other major aquifers in the area	South Lincolnshire: Chalk (above); Triassic sandstone; Magnesian limestone; Carboniferous imestone (all below) Norfolk: Crag; Chalk (both above); Triassic sandstone; Magnesian limestone; Permian sandstone; Carboniferous limestone (all below) Southern England including Oxfordshire and Buckinghamshire: Chalk (above); Triassic sandstone; Permian sandstone; Carboniferous limestone (all below)
Other shales or clays in the area	South Lincolnshire: Bowland Shale Formation; Craven Group (below)
Aquifer map	Lower Greensandprincipal aquifer
Shale/clay map	Lias Group shale/clay unit

lg-l — Lower Greensand/Lias Group separation map. BGS © UKRI.

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