Chronology, climate and marine record. The Devensian Stage: its development, limits and substages

Abstract

The name Devensian for the last glacial stage of the British Pleistocene arose from the attempt of the Quaternary subcommittee of the Stratigraphic Committee of the Geological Society of London to define the divisions of the British Quaternary and to draw up correlation tables. The name of the stage derives from the location of the stratotype. Although the stage is broadly equivalent to the Weichselian of NW Europe and the Wisconsinan of North America, exact equivalence of the boundary limits and of substages in the British sequence to overseas divisions should not be assumed. As a means of correlation, radiocarbon dating is of great use in the later half of the stage, and a few ‘enriched’ dates help in a few millennia before 50 000 B.P. No other methods of absolute dating have yet been applied, and the possibility of doing these on the land-based Devensian deposits is remote. Significant recognizable events in a glacial stage are provided by interstadials. Claimed interstadials in the Weichselian of NW Europe are briefly examined, and the evidence for interstadials in the British Isles is summarily presented and compared as far as possible with the continental succession. On the question of when, in the Devensian, the British area was physically ‘glacierized’, it is claimed that so far there is no evidence for this in the Early Devensian. The timing and duration of the well-established Late Devensian glaciation is discussed, and a word of caution is sounded against regarding this as synchronous throughout the area.