Weichselian stratigraphy and radiocarbon dating in South Wales

Abstract

There are many difficulties involved in both the interpretation and correlation of Weichselian deposits in South Wales - a fact illustrated by the multiplicity of viewpoints in the literature. It is suggested that the Weichselian stage was characterised by (1) an early prolonged periglacial phase, possibly with local upland glaciation and with some climatic fluctuations; (2) a major glaciation in which Irish Sea ice and Welsh ice played different relative roles in different areas; and (3) a shorter periglacial phase with some corrie glaciation in the uplands. There are four radiocarbon dates for the Late-glacial. The dates from Port Talbot (Glam.) confirm the age of organic deposits from Swansea Bay and provide an approximate date for the onset of the Flandrian transgression; and the date from Aberaeron (Cards.) points to the existence of Zone II organic deposits beneath solifluction earth and above glacial drifts of probable Weichselian age. There are also four dates for the Middle Weichselian, supporting other evidence for an interstadial at this time and for a later extensive glaciation by the Irish Sea glacier in Cardigan Bay. There is no unequivocal age determination for the organic content of the calcareous Irish Sea till. Palaeobotanical investigations undertaken so far have revealed that a wide range of organic material exists in the glacial drifts, including a significant amount of Tertiary pollen and spores and many fragments of Tertiary lignite. It is therefore difficult to relate the palaeobotanical evidence with any confidence to either the stratigraphy or the radiocarbon dates. However, an interglacial deposit discovered in situ at West Angle (Pembs.) may provide another pointer to the true age of the South Wales drifts; and the radiocarbon date for the human skeleton from Paviland (Glam.) should also be of major significance for the establishment of a reliable Weichselian chronology.