Wang Jingtai, Edward Derbyshire
During the last Pleistocene glaciation, a broad zone of severe perigla-cial environment outside the ice-sheet limits stretched eastwards across the north European plain from southern Britain into Germany and beyond. The periglacial features include ice-wedge casts, sand wedges, cryoturbation structures (involutions) and patterned ground, solifluction sheets, frost mounds, and pingoes. Two main periods of ice-wedge formation are indicated during the last (Weichselian) glaciation: 60,000 to 50,000yr.B.P.and 25,000 to 15,000 yr. B.P..The evidence of permafrost, together with pollen and other data,suggests a mean annual temperature of about -6℃.Aeolian sand sheets of Pleistocene cover large areas of north-western Europe between northern France and the Baltic Sea. It rarely exceeds 2m in thickness and consists mainly of silty fine sand with planar bedding, sometimes laminated. Grain size decreases from NW to SE, silt content increasing. It grades into loessic silts towards the SE. Two major episodes are recorded in the Older Cover Sands, correlated with the middle and late phases of the Weichselian glacial stage. The European Loess Belt extends into the U.S.S.R., but in western Europe it is very different from the loess of China. The deposits are rarely more than 10m thick, many of them being laminated and showing widespread evidence of transport by running water and disturbance by frost cracking and heaving. They are best described as loesslike sediments.
