Introduction and geological background

In the late Neogene, the sea progressively retreated from wide areas of the northwestern lowlands of the North German–Polish coastal basin. Large river systems that developed in the exposed areas drained generally toward the west, laying down great amounts of fluviatile-limnic sediments. The lithology of pebbles contained in these sediments indicates that the major source area was in what is now the eastern Baltic Sea, between central Sweden and the Baltic countries. On the other hand, the presence of lydite (radiolarian chert) demonstrates that some material was also derived from the south, primarily the Bohemian Massif (Hucke, 1928; Ahrens et al., 1968; Duphorn et al., 1973; Ahrens and Lotsch, 1976). In the southern parts of Thuringia, in the area of the Thiiringer Wald, there was limited late Neogene sedimentation in subsident areas (Figure 18.1).

Northern lowlands and northeastern region

In the northern lowlands, Lower Pliocene terrestrial deposits appear to have been extensive, but only in southwestern Mecklenburg have erosion relicts been preserved. As far as we know, deposits of Plio–Pleistocene transitional series can be found only in the southwestern parts of this area (Ahrens et al., 1968).

The best-known locality of this type is Rüterberg, where the lower horizons of the sequence (Bergton-Diatomit-Silbersand complex) are followed discordantly by the Loosener Kiese (Gehl, 1958; von Bülow, 1964), a unit characterized by a mixture of “southern” pebbles (Kieselschiefer, etc.) and silicified rocks and intensely weathered granite from the north. The Bergton-Diatomit-Silbersand complex was formerly correlated by Krutzsch (1959) to the Reuverian or a still earlier stage on the basis of pollen, but more recently this unit has been correlated with the Upper Miocene (Lotsch, 1981; Krutzsch, 1988).