Weichselian

The final glacial advance, c 115,000-10,000 bp, corresponding to the Alpine Würm, American Wisconsinan, and British Devensian. The Weichsel Glacial Stage followed the Eemian Interglacial Stage and marks the last major incursion of Pleistocene continental ice sheets. It is named for the ice sheet of north Germany and other Quaternary glacial deposits in northwest Europe. Most of the Weichselian is within the range of radiocarbon dating. The ice sheets were probably at their maximum size for only a short period, between 30,000-13,000 bp; eight interstadials have been recognized in the Weichselian of northwest Europe. The late Weichsel expansion of the Scandinavian continental ice sheet began about 25,000 years ago; most of the Weichselian sediments over northern Europe are part of this late Weichselian cold period.

Group of Quaternary glacial deposits in northwest Europe (see Table 5, page 418). The main feature is a striking group of end moraines, demarcating the maximum extent of the Weichsel ice-sheet. This ice-sheet flowed out from centres in Scandinavia, over the bed of the Baltic Sea and into northern Europe and the Soviet Union (where the moraines are called the Waldai moraines). The final retreat of the ice is marked by a succession of end moraine complexes, whose chronology has been worked out from varves. Most of the Weichselian is within the range of radio carbon dating. Dates vary between greater than 70,000 bp and 10,000 bp, and the Weichselian can be correlated with the British Devensian. Both Weichselian and Devensian represent one cold stage which probably lasted from about 120,000 bp until 10,000 bp. The ice sheets were probably at their maximum size for only a short period, between 30,000 and 13,000 bp. At other times during the Weichselian, they were probably much less extensive. Outside the ice-sheet margins, great thicknesses of loess and cover-sand were deposited. Within these deposits is a series of palaeosols, which have been shown by pollen analysis to represent a series of interstadials. Increases in tree pollen have been taken to mark the climatic amelioration of each interstadial. Four interstadials have been recognized in Dutch deposits Amers-foort, Moershoofd (50,000-43,000 bp), Hengelo (c39,000 bp) and Denekamp (c30,000 bp). Three further interstadials were recognized in Denmark: Brorup, Bolling (13,000-12,000 bp) and Allerod (11,80011,000 bp). Another has been identified in north German deposits the Odderade interstadial (<58,000 bp). The stadial between the Bolling and Altered interstadials has been called the Older Dryas, and the stadial between the Altered and the end of the Weichselian, the Younger Dryas. All the interstadials have been dated by radiocarbon. Amersfoort and Brarup have yielded dates of 68-65,000 bp and 63-61,000 bp respectively, but these are at the extreme limit of the technique and the interstadials may be considerably earlier. Thus altogether eight interstadials have been recognized in the Weichselian of northwest Europe. They are difficult to correlate with the three British Devensian interstadials. The British Upton Warren interstadial complex (45,00025,000 bp) overlaps Hengelo and Denekamp, and the British Windermere interstadial (13,000-11,000 bp) overlaps Bolling and Altered. Levalloisian, Mousterian and Upper Palaeolithic artefacts are found in Weichselian deposits, particularly in the French caves, as are fossils of Homo sapiens. The terms Weichselian, Bolling, Allerod etc should not be applied outside continental Europe, although some archaeological texts still mistakenly use them to describe events of a similar age in Britain.