The Last Glaciation and Geomorphology

Abstract

The Weichselian ice sheets were smaller than those of the preceding Middle Pleistocene and covered only the north-eastern part of the German lowland, as well as the eastern and northern parts of the Jutland peninsula. The Late Weichselian (Late Devensian) ice sheet also covered the northern part of the North Sea Basin (Ehlers and Wingfield 1991). The young morainic landscape still has distinct morphological features distinguishing it from the old morainic areas with relief shaped by the long-lasting periglacial processes during the Weichselian. The area of the last glaciation is easily recognizable on topographical maps owing to the irregular relief and the numerous lakes that are still preserved today. This scenic landscape also features end moraines and kames, till plains, and huge meltwater valleys (pradolinas or Urstromtäler), as well as a complex drainage system. The general climatic development of the last interglacial- glacial-Holocene cycle can be interpreted from curves showing the ratio of the oxygen isotopes 18O and 16O in deep-sea sediments, which is indirectly indicative of the growth of ice masses worldwide. The different OIS (Oxygen Isotope Stages) are numbered, with uneven numbers representing the relatively warmer phases. OIS 5e corresponds to the Eemian Interglacial. The stages 5d–5a represent the Early Weichselian, which is colder than the preceding interglacial but is subdivided into stadials and interstadials. The Brørup interstadial s.l., including both the Amersfoort (5c) and the Odderade interstadial (5a), is characterized by boreal forests in this part of Europe. OIS 4 marks the onset of the Middle Weichselian or Pleniglacial, and is the first stage involving much lower temperatures and the growth of considerable ice masses. This is probably the time when a real inland ice sheet started to grow in Fennoscandia. OIS 3, the middle part of the Pleniglacial, is represented by several climatic changes. The interstadials—or intervals, as they are also called—such as Oerel, Glinde, Moershoofd, Hengelo, and Denekamp—are well documented by terrestrial palynological records of a herb and shrub bush vegetation (van der Hammen et al. 1967; Behre 1989; Caspers and Freund 2001).