Abundant as the remains of the Mammoth and its associated group of Pleistocene Mammalia are in the adjacent valleys of the Medway and the Cray, none have been yet recorded in the valley of the Darent, to which the Mammoth no doubt commonly resorted at the same time. One reason may be that this valley is very bare of Drift, and between Dartford and Otford there is not a single pit in the little drift-gravel that is met with.