The Gault Clay is a formation of stiff blue clay eposited in a calm, fairly deep water marine environment during the Lower Cretaceous Period (Upper and Middle Albian). It is well exposed in the coastal cliffs at Copt Point in Folkestone, Kent, England, where it overlays the Lower Greensand formation,and is found in exposure on the south side of The North Downs and the north side of the South Downs. It is also to be found beneath the scarp of the White Horse Hills, in the Vale of White Horse, in Oxfordshire, England, and on the Isle of Wight where it is known as Blue Slipper. The Gault underlies the chalk beneath the London Basin, generally overlying eroded rocks of Jurassic and Devonian age; the lower Gault is present only below the outer parts of the basin and is absent under central London..