Age of the Upper Boulder Clay Glaciation in the Midlands

Abstract

THE radiocarbon dating of 30–36,000 yr provided by Shotton¹ for peaty samples obtained from gravels occurring beneath the Upper Boulder Clay of the Four Ashes area [SJ9208], situated about 5 miles north of Wolver-hampton, is probably the most important advance in absolute Pleistocene chronology yet achieved by the method of age determination in the English Midlands. It has proved that the Upper Boulder Clay is a viable time-stratigraphic unit within the Shropshire–Cheshire Basin^2,3 and disproved the hypothesis that the maximum limit of advance of the ice-sheet which laid down the Upper Boulder Clay in north Cheshire reached only as far as the Wrexham–Bar Hill morainic suite situated in the centre of the Shropshire–Cheshire Basin⁴. By inference this dating must support the view that the complex Wrexham–Bar Hill end-moraine is of pre-Upper Boulder Clay (Middle Sands) age^2,3 and therefore cannot be correlated with the Brandenberg and Lesnow moraines as suggested by Boulton and Worsley⁴. Furthermore, it also shows that the variations in carbonate leaching properties discovered by Boulton and Worsley in the Upper Boulder Clay to the north and south of this morainic suite are not necessarily indicative of age differences between these deposits as suggested by them⁴.