A new interglacial stage in Poland (Augustovian) and the problem of the age of the oldest Pleistocene till

Abstract

Several new boreholes have been investigated in northeastern Poland. They proved up to ten undisturbed till beds in superposition. Two interglacial lacustrine sequences have also been found. The lower interglacial sequence rests on the oldest till in the region and is probably overlain by two Elsterian tills. The upper interglacial sequence rests directly upon the latter two tills and has yielded a pollen succession typical of the Mazovian (Holsteinian) stage. The lower interglacial sequence shows a different pollen succession, unlike any other known in Poland. It has been therefore defined as a new, Augustovian interglacial stage, containing two warm events (optimum phases) separated by a cold period with only boreal flora. The lithostratigraphical position of the new interglacial suggests a classical Cromerian age. However, although the pollen succession of the upper optimum stage of the Augustovian is superficially very similar to the British Pastonian, correlation with the Leerdam Interglacial is possible, but it may also represent a completely new warm episode of the Cromerian. The paper presents discussion on possible different age interpretations of this warm stage and the underlying till.