The terraces of the rivers Thame and Thames and their bearing on the chronology of glaciation in central and eastern England

Abstract

The newly surveyed terraces of the River Thame are correlated with those of the Upper Thames, principally on the basis of apparent continuity of long profiles. This fixes the levels of the terraces of the Upper Thames at the Thame/Thames confluence at Dorchester, close to the ‘Goring Gap’, allowing correlation with the terraces of the Middle Thames to be more firmly established than hitherto. Anglian glacial deposits in the headwaters of the Thame appear to be broadly contemporaneous with those of the Wolvercote Terrace of the Upper Thames and Evenlode. An analogous relationship between the Wolvercote Terrace deposits and the glacial ‘Moreton Drift’, previously suggested by many workers is upheld, supporting the view that the Moreton Drift is itself Anglian. However, the relationship of the Wolvercote Terrace with the Middle Thames terrace succession suggests that the Anglian deposits of the Evenlode and Thame valleys are significantly younger than those in the Vale of St Albans. An hypothesis which explains these observations is that the Anglian Stage comprised two separate glacial phases together with an intervening temperate episode. Published amino acid racemization data suggest that the glaciations correspond with Oxygen Isotope stages 12 and 10 of the deep sea record, and the temperate phase with Oxygen Isotope Stage 11; the deposits of the latter ‘Swanscombian Interglacial’ are similar in palynological character to those of the Hoxnian of Hoxne (Oxygen Isotope Stage 9). It is suggested that deposits ascribed to the Anglian glaciation include deposits from both stages 12 and 10, and that much of the Anglian glacial succession of central and eastern England, hitherto ascribed to Stage 12, including the ‘Wolston Series’ of the original ‘Wolstonian’ stratotype and perhaps also the Lowestoft Till of the Anglian stratotype, were deposited during the younger Stage 10.