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.
On top of these clays is a distinct layer of Upper Greensand above which lies a rolling bed of white limestone about 200 meters thick. In the lower levels of the Lower Limestone and in the lower regions of the Middle Limestone there are abundant fossilized shell fragments, especially Inoceramus clams.