CLIMATE-RELATED RIVER ACTIVITY AT THE WEICHSELIAN HOLOCENE TRANSITION- A COMPARATIVE-STUDY OF THE WARTA AND MAAS RIVERS

Fluvial systems from the Dutch and Polish lowlands are compared for th eir evolution during the Weichselian deglaciation period. In both regi ons the Pleniglacial braided-river pattern changed to a meandering pat tern in the beginning of the Lateglacial. Several transitional stages between braided and high-sinuosity meandering systems have been recogn ized. A difference in fluvial activity is found during the Younger Dry as when the Maas transformed to a braided pattern while the Warta main tained its meandering pattern. Phases of erosion and aggradation are m ore or less synchronous in the different river basins, but their inten sity may differ greatly. The major characteristics of the fluvial syst ems are obviously a response to the general climatic evolution and rel ated to changes in vegetation. The regional differences are of minor i mportance and can be explained by site-specific factors. Threshold val ues within the latter factors define the changes in river dynamics.