Późnovistuliański rozwój sieci rzecznej w rejonie Kotliny Toruńskiej na tle struktur starszego podłoża
Little attention has been devoted to tectonic movements of the Mesozoic structures underlying the Toruń Basin so far. The eastern section of the Noteć ice marginal streamway, including the Toruń Basin, is located diagonally in relation to the Middle-Polish swell. Its tectonic uplifting might have halted the westward outflow along the ice marginal streamway and caused the Vistula river bed to be shifted north-westerly within the Toruń Basin (Lencewicz 1922, 1923, Galon 1934, Mojski 1980,
... ojski 1980, Brykczyński 1986). The area where the Toruń Basin overlays the Middle-Polish swell contains salt banks, pillows and swells (Fig. 1). The process of postglacial activation of these structures might have been modified by glacioisostatic motion, halokinetics of the Mesozoic elevations, increased intensity of geothermal heat flow and the activity of the main fault lines, all depending on changeable pressure exerted by the ice sheet and following the rules of diverse load. The above motions might have brought about the changes in the river valley network in the area of the Toruń-Bydgoszcz hydrographic region. Moreover, they might have triggered the formation of the elevated parts of the basin itself and the basin's vicinity, the location of which reflects the location of salt structures in the Mesozoic substratum (Fig. 1). Tectonic activity of the above structures during the Pomeranian phase of the Vistulian glaciation led to shifting the melt water outflow route from the southern section of the Mesozoic elevation of Szubin towards its northern slope in the vicinity of Nakło on the Noteć. Tectonic uplifting of both this structure and the anticline of Nakło gave rise to a narrow section of the ice marginal streamway in the vicinity of Nakło, which shows the features of the antecedent gorge. Later on this process also contributed to halting the outflow in the Noteć-Warta ice marginal streamway. Similar development of the river network can be traced down at the early stages of both Great and Eem Interglacial (Fig. 2, 3).