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Abstract:

The target of this study is the geological documentation of the environmental changes in this area, from the beginning of Late Pleistocene to historic times. The Berettyóújfalu — Somona area is situated on the northern border of the Nagy Sárrét wetland, functioned as local basin of Derecske Trench, collecting the sediments of the Berettyó–Kőrös river system. On the north, the platty, E–W oriented ridge of older, Late Pleistocene deposits forms the border line of the wetland. Both Neolothic and historic settlements got favourable natural conditions by extended pasture fields and sources of wetland. In this area, sedimentological, mineralogical and paleontological (sporo-palynological) analyses were performed. In this way, the Late Pleistocene sediments of the river of the Old Tisza (Tisa) were separated from Holocene deposits, originated from Apuseni Mts. by the river of Berettyó (Barcu). While in Nagy Sárrét, the whole Holocene is documented, but in Somona area, only the Borela–Atlantic transition appears. The climatic conditions varie from the cold and dry steppe in the final phase of Ice Age, until the Preboreal, Subatlantic and Boreal climatic phases, i.e. and the morphology of the area evaluated from the large floodplain, to the E-W oriented elevation with neotectonical origin. The last changes in the landscape of this area were caused by the regularization of Berettyó-Kőrös river system, which leaded to the drainage of the whole Nagy Sárrét.