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and investigated (the valleys of Odra, Warta, Pilica, Vistula, Wieprz and Bug Rivers). A good example is the present-day valley of Wieprz River in the northem foreland of the Lublin Upland (Serniki cross-section, Fig. 5). The age is here documented by limnic seąuence of Mazowian age, which covers 120 m thick fluvial and glacifluvial seąuence with beds of till o kier than Mazowian Glaciations (San 1 and San 2 ?). But the shape of the valley at Serniki is fully comparable with the shapes of subglacial channels at Niczonów and Objezierze. Such a comparison (Fig. 5) shows the difficulties with the river valleys reconstructions in the Polish Lowland.

In the same area (foreland of the Lublin Upland!) occur invisible, or poorly yisible in the present-day topography buried, deeply and narrowly burried subglacial channels originated probably during the Odranian Glaciation or during the older cold stages. An unequivocal example is subglacial channel in the northem foreland of Lublin Upland (Harasimiuk, Henkiel 1981), 30 km east of Lublin. It is incised 100 m deep in the Upper Cretaceous karst topography. Similar subglacial channels are very often found at the Sudetic Foreland (Michniewicz 1998).

The similar difficulties with the distinction between river valleys and subglacial channels, occuring in some regions, are connected with smali amount of bore-holes profile and with later shape of their disturbances of ones. Ver-tical movements of tectonic origin as well as glaciotectonic processes are of great importance. The first are very common, but they are differenciated in space and time. The records from recently obtained data (Liszkowski 1982) show, that the territory of country have the amplitudę between land -1 mm (newest data to -2 mm pro year, Kurzawa 2003), namely between 100 m (east-em Poland) and -100 m (western Poland) pro last 100 ka. If so the primary situation of Eemian valley hight has been changed up to 100 or-100 m. But for the Mazowian ones up to 300 or -300 m. The last value is impossible, because presently the level of the Mazowian sea deposits lies between 20 m a.s.l. at the western Poland and -20 m b.s.l. in the northem Poland (Fig. 1). The dimensions of vertical movements were smaller.

4. As an example of the course of the Mazowian river valley is demonstrat-ed the Vistula valley (Fig. 6). In the Carpathians (Zuchiewicz 1995) and in the South Polish Uplands (Pożaryski et al. 1994; Lindner, Marks 1999) the level of the Vistula channel is well documented owing to developed channel deposits visible in the outcrops and present topography. Moving from War-saw to the north, the course of the Mazowiam Vistula valley is known insuf-ficiently. Fig. 6 shows the various places where suitable deposits have been found.