The Pleistocene History of the Birmingham District

The Birmingham district in the West Midlands of England contains a complex sequence of Middle to Late Pleistocene sediments attributed to at least three lowland glaciations (Anglian, Wolstonian, and Devensian) as well as a variety of non-glacial sediments. Understanding the age of the Pleistocene glacial deposits is critical to reconstructing the palaeoenvironmental history of the district and its relationships with adjacent regions. The exact age of the Middle Pleistocene glacial deposits, however, is disputed, with one hypothesis favouring ‘Wolstonian’ glaciation intermediate in age between the Hoxnian and the Ipswichian interglacial stages, and another hypothesis favouring an older (pre-Hoxnian) glaciation during the Anglian Stage (equated with Marine Isotope Stage (MIS) 12). To resolve this dispute, the present study seeks to establish a new regional stratigraphy of the Birmingham district and to re-evaluate its palaeoenvironmental history, supported by optically stimulated luminescence (OSL) dating, cosmogenic exposure dating, and palynology. The results reject the hypothesis of glaciation during the Anglian Stage and instead support that of Wolstonian glaciation. Field observations of the sedimentological properties of glacial sequences at sites in three regions of the Birmingham district indicate that the glacial stratigraphy was controlled to the east by the Irish Sea and North-East ice (around the sites of Wolston, Glebe Farm, Meriden Quarry, Park Farm, and Gilson) and to the west by Welsh ice (around the sites of Seisdon and Frankley). The sites are correlated across the district using lithostratigraphy, chronostratigraphy, and biostratigraphy. Overall, their geological evidence establishes the former presence of Wolstonian glacial ice in the Birmingham district about c.183.5 ka, during MIS 6. This reconstruction is consistent with evidence for Wolstonian glacial ice at a similar time in eastern England and to the equivalent Saalian glaciation of continental Europe