Plio–Pleistocene in England

The so-called Crag formations of East Anglia are the only British examples of a sedimentary sequence that is partly Pliocene and partly early Pleistocene. They are composed of marine near-shore and estuarine shelly sands and clays, in some horizons with good pollen assemblages. The oldest unit, the Coralline Crag, has always been accepted as Pliocene. Early attempts to locate the base of the Pleistocene in that sequence were guided by the belief that its position would be indicated by evidence of a sharp drop in temperature. Thus, at the International Geological Congress in 1948, it was recommended (King and Oakley, 1949) that in England the Neogene–Quaternary boundary should be placed in the East Anglian sequence at the base of the Butleyan Red Crag, the highest and youngest of Harmer's (1902) three Red Crag “zones.” A number of authors (e.g., Boswell, 1952) subsequently proposed that it should be lowered to the base of the Red Crag, on the assumption that the transition from the underlying Coralline Crag indicated a major climatic deterioration. On the premise that the boundary was associated with the Olduvai normal paleomagnetic event, Hey (1977) and Funnell (1977) independently concluded that in East Anglia it could lie above the top of the Red Crag.

It must be emphasized that the paleomagnetic data available from the East Anglian succession are scanty (Van Montfrans, 1971, pp. 100–101), and materials suitable for radiometric dating appear to be absent.