Ipswichian

The last interglacial of Britain, equivalent to the Eemian Interglacial of North Europe, with its type site at Bobbit's Hole, Ipswich. The Alpine equivalent is the Riss-Würm and the Sangamon in the North America equivalent. The deposits indicate warm conditions with evidence of vertebrate fossils. One radiocarbon date of 174,000 @ 30,000 bp has been found. Levalloisian and Mousterian artifacts are found in Ipswichian deposits.

A group of British interglacial deposits — lacustrine muds, river terraces, estuarine and marine sediments. They exist as patches of material containing fossils indicating warm conditions, overlain by Devens-ian deposits and also underlain by sediments indicating cold conditions. Individual patches have been correlated by pollen analysis and the evidence of vertebrate fossils. A climate warmer than the present is indicated. Nowhere is there any direct evidence of the underlying stratigraphy, but Ipswichian terraces in the Midlands have been shown to be later than Wolstonian sands and tills. Traditionally, the Ipswichian deposits are supposed to represent a single warm stage, the last interglacial. This may be supported by a pioneer uranium series date of 174,000 ± 30,000 bp for supposed Ipswichian deposits at Brundon in Essex. Such a date fits in well with the expected age of the last interglacial and with the deep sea core oxygen isotope sequence. There is, however, no direct connection between the patches of deposit, and recent discussion of the vertebrate fossil assemblages by which the Ipswichian is correlated has suggested that the deposits may in fact represent more than one interglacial. Further developments are awaited. Levalloisian and Mousterian artefacts are found in Ipswichian deposits. See Table 6, page 419.