On top of these clays is a non-contiguous layer of Upper Greensand above which lies a rolling bed of white chalk about 200 metres thick. In the Lower Chalk and in the lower region of the Middle Chalk there are abundant fossilized shell fragments, especially Inoceramus clams.
Above these clays is a separate layer of Upper Greensand, followed by a rolling layer of white chalk approximately 200 meters thick. The lower levels of the Lower Chalk and the lower sections of the Middle Chalk contain numerous fossilized shell fragments, particularly Inoceramus clams.