Chapter 7 - Pleistocene Glaciation Limits in Great Britain

Abstract

Abstract The Pleistocene sequence of Great Britain can be broadly divided into two major parts: the pre-glacial Pleistocene and the glacial Pleistocene. The bulk of the evidence for the pre-glacial Pleistocene is restricted to south and east England and particularly to East Anglia. No direct evidence for glaciation is known from these sequences, although indirect evidence for glaciation is seen as erratic clasts in fluvial sediments. The earliest undisputed glacial sediment is the Happisburgh Diamicton, which is of Anglian (= Elsterian, MIS 12) age. This glaciation is best developed in east- and south-central England, although sediments are known to extend as far as south Wales. This phase saw the most extensive glaciation of Britain. Anglian-age glaciogenic sediments also occur offshore in the southern North Sea and Irish Sea basins. The second glaciation episode is of late Middle Pleistocene age, intermediate between the Hoxnian (= Holsteinian ~ MIS 11c) and Ipswichian (= Eemian ~ MIS 5e) interglacial Stages. This Wolstonian glaciation was originally recognised in the English Midlands; a younger Middle Pleistocene glacigenic sequence is also known from eastern England. Because it was apparently of similar extent to that in the subsequent Devensian Stage, this glacial episode is much more poorly represented in the Pleistocene record. The third, or Devensian (= Weichselian, ca. MIS 4–2) glaciation is well represented throughout most of glaciated Britain, yet it was possibly the least extensive of the three major events. Although considerable detail is known about its retreat phases, comparatively little evidence is available about the ice-sheet's advance. In general, ice extended outwards from the mountain glacial centres, reaching a maximum at about 27 ka, then retreating in an oscillatory manner until 13 ka. Following the Late-glacial Interstadial, the ice readvanced in the Loch Lomond Stadial (= Younger Dryas Stadial).