MAJOR PALAEOHYDROGRAPHIC CHANGES IN ALPINE FORELAND DURING THE PLIOCENE-PLEISTOCENE

The changing palaeogeographical pattern of Alpine deposits across the European forelands can be traced by identifying mineral assemblages an d establishing the chronology of Pliocene-Pleistocene deposits in Alpi ne foreland. In the late Miocene, the upper courses of the Rhine and t he Aar flowed east from the Swiss molasse plain towards the Danube. In the early Pliocene (Brunssumian, 5-3.2 Ma), these same rivers headed northwards towards the Rhine Graben of Alsace. In the early Reuverian, these streams were captured south of the Rhine Graben by the Doubs. T hey ceased their northward flow and headed west to feed the Bresse Gra ben. This phase is dated to the Lower and Middle Reuverian (3.2-2.6 Ma ). From the Upper Reuverian (2.6 Ma) to the present day, the Rhine has adapted approximately its present course towards the North Sea, south to north along the Rhine Graben and across the Rhine Schist Massif to feed the Dutch Grabens. This changing pattern of capture and alterati on of the hydrographic system of the upper reaches of the Rhine and th e Aar can be explained by local tectonic movements.