Pleistocene vegetational history and geology in Norfolk, with an appendix on the non-marine mollusca from Swanton Morley

Abstract

Three Ipswichian Interglacial sites are described, at Mundesley on the northeast Norfolk coast, and at Beetley and Swanton Morley in central Norfolk. Two Hoxnian Interglacial sites are also described, at Barford and Dunston, again in central Norfolk. Pollen diagrams from boreholes in channel sediments cutting the Contorted Drift at Mundesley span zones lbto III of the Ipswichian Interglacial, and a Devensian age for the Drift or for the ice movements producing the contortions must be discounted. ‘Cannonshot’ gravels at Beetley, considered to belong to the Wolstonian retreat, are overlain by organic layers indicating zone II of the Ipswichian Interglacial, and a Devensian interstadial. Interesting plant records includeDamasonium alismain the interglacial deposits, andPicea abiescf. ssp. obovata andBruckenthalia spiculifoliain the interstadial beds. Fossils in organic deposits at Swanton Morley, late Wolstonian to early Devensian in age and pocketed in floodplain sands and gravels, include the exoticAcer monspessulanum, and mammalian bones referred to Ipswichian zone III. At Barford, organic lake deposits of the Hoxnian Interglacial overlie Anglian boulder clay which lies in a deep channel in the Chalk. The organic beds, which are of late Anglian to Hoxnian zone III age, are overlain in turn by solifluction deposits and by a cannonshot gravel attributed to the Wolstonian retreat. The high non-tree pollen phase recorded at Hoxne and Marks Tey in subzone Ho IIcis also found here. Pollen from lake deposits at Dunston indicates subzone Ho IIIband zone Ho IV, and there is palynological evidence for widespread erosion in zone Ho IV.