Radiocarbon dated wood debris in floodplain deposits of the San river in the Bieszczady Mountains

Tree logs and smaller fragments of wood debris occur in floodplain alluvium (1-3 m above the river level) of the San river in the Bieszczady Mountains (Polish East Carpathians). The greatest accumulations of wood debris occur in the lower part of the alluvium, beneath a layer of sandy muds. The wood debris in these accumulations was dated by radiocarbon method. The dates fall within the time interval 3270š70 BP to 103.7š1.1 pMC, but most of them are from 17 th to 19 th century. The abundance of the wood debris in the alluvium is the result of its intense supply to the river channel, caused by deforestation and large floods. The age of the wood accumulations corresponds to the phase of settlement in the upper San valley in the 16 th to 17 th centuries. The older wood debris could be redeposited to the young alluvium from older alluvial terraces.