РусSeveral world-wide known Pleistocene stratigraphic key areas and units have been derived from central Europe e.g. Saalian, Vistulian (Weichselian), Wartanian and Holsteinian. A thick marker bed of the late Elsterian glaciolacustrine silts and clays, overlain by sediments of the Holsteinian sea, is useful for stratigraphic and palaeogeographic correlation in central and eastern Europe. In Poland there is an extensive palaeogeographic and stratigraphic gap (0.9 to 1.2 million years long) between the boundary Tertiary/Quaternary and the first Pleistocene glaciation. Bi-optimal interglacials e.g. Augustovian and Ferdynandovian can represent two separate interglacials, with a cold interval between them. Ice sheets of the Wartanian and the Middle Vistulian Glaciations could be more widespread in this country.