Coastal interglacial deposits of the English Channel

Publisher Website
Google Scholar
Abstract
Fossiliferous Late-Pleistocene deposits on the foreshore of the English Channel at Selsey (Sussex), Stone (Hampshire), and near Arromanches (Calvados), have been investigated. At each site analyses of pollen, macroscopic plant remains and Mollusca have been made and from these vegetational, faunal, environmental and climatic conditions have been reconstructed. At Selsey, it is shown that the deposits, which lie in a channel cut in Eocene rocks, are of Ipswichian (Eemian or Last) Interglacial age. Pollen analysis of the sediments of the channel filling show they were formed during zonesb,c,d,eandfof this interglacial from open parkland vegetation to birch-, to pine-, to oak-dominated forests. Analysis of the macroscopic plant remains and of the molluscs suggests a rapid climatic amelioration at the beginning of the interglacial, so that by the beginning of zonefthere are indications of summer warmth exceeding that of the present day in the area. In the upper part of the channel filling, estuarine deposits overlie freshwater deposits. It is shown that the marine transgression causing the change was taking place in zonefand was probably responsible later for the raised beach deposits which overlie the channel deposits and which form the cliffs at Selsey Bill. At Stone pollen analysis shows that brackish water deposits, below present high tide level, were formed in zonefof the Ipswichian Interglacial. At that timeQuercus,PinusandAcerwere the chief trees forming the forest in the region. The macroscopic plant remains and the Mollusca indicate that the deposit was formed under saltmarsh conditions. As at Selsey, the raised beach gravel found overlying the interglacial deposit is related to the same marine transgression that produced the brackish water conditions. Near Arromanches, at St Côme de Fresne and Asnelles-Belle-Plage, two deposits showing a change from marine to freshwater sediments were investigated. The analysis of pollen and the Mollusca showed the prevalence of pine forest and its replacement by open steppe-like conditions as the marine regression occurred. After the regression, limon covered the freshwater deposits. The fossiliferous deposits are tentatively correlated with zoneiof the Eemian Interglacial. The relative land- and sea-level changes indicated by all the deposits are considered. It is concluded that in the English Channel, during the Ipswichian (Eemian) Interglacial, sea level rose above its present height in zonefand fell below it during zonei. The Selsey-Brighton raised beach and the Normannien II raised beach are correlated with the same marine transgression. It is pointed out that if the Selsey-Brighton raised beach is to be correlated with the Monastirian II level of 7—8 m, then this level should be correlated with the Ipswichian (Eemian) Interglacial.

This publication has 7 references indexed in Scilit: