ABSTRACT
This chapter explores how the chalk beds dipping down gently in the Chilterns to the north, and the North Downs to south of the Lower Thames. It is reasonable to guess that there are chalk beds under London joining the two areas where chalk comes to the surface. Under the chalk in eastern England are clays such as the Oxford clay, and sands, all laid down in shallow water with thin beds of limestone. Below these is a great variety of much older and harder rocks, laid down in Paleozoic times, and including coal measures. When England next sinks under the sea, as it probably will in the next hundred million years, mud will be laid down on the submerged surface, and the valleys gradually filled up. More remarkable, something about the actual nature of rocks from speed at which shock waves move through them. Below Corby the waves move very quickly and the few borings show volcanic rocks.
