Helena Alexanderson

Both high-mountain rivers and wet-based mountain glaciers are considered effective erosion agents. They acted alternatively or simultaneously during the late Quaternary in the Tatra Mountains (West Carpathians) thus producing a vast amount of clastic material that was subject to deposition, reworking and transportation downstream. A small fraction of that amount of the material is still preserved in the Białka River valley beyond the Tatra Mountains, as relics of alluvial mantles. These remnants of former river floodplains are records of the time scale of alluvial accommodation and river incision. New luminescence data, based on quartz grains, are now available for one of the alluvial accumulation levels that is 40–15 m high above the present-day river channel, and the geochronological investigations yield ages from 64.2 to 26.7 ka ago. While this time span was dominated by temperate climate conditions during MIS 3, it demonstrates that neither glaciers nor cold climate conditions prevailed during that phase of alluviation within the Białka River valley. This also shows the lack of meaningful fluvial incision during MIS 3, in contrast to the subsequent MIS 2, including the Last Glacial Maximum. An average rate of river incision was calculated based on the OSL (optically stimulated luminescence) data, and then this value was extrapolated back in time leading us to assume that (i) the age of the residual till of the Hurkotne unit is MIS 16, and (ii) no deepening occurred in the Tatra's reach of the Białka River valley since MIS 8.