Deposits of Neolithic water soil erosion in the loess region of the Malopolska Upland (S Poland) - A case study of the settlement micro-region in Bronocice

摘要

In the well-known settlement micro-region of the Malopolska Upland - known for extensive studies into the Neolithic agricultural anthropopressure - the authors have re-examined three selected Holocene soil-sediment sequences derived from soil erosion by water. The macroscopic features of both colluvium and proluvium (deposits of gully erosion) from an area of very strong Neolithic anthropopressure in the Nidzica River Basin have been described, and analyses of the basic characteristics of sediments and fossil soils as well as micromorphological analyses performed. 40 samples were dated with the SAR OSL method. The results of C-14 and OSL dating point to the stabilization of loess slopes in the Holocene until the intensification of agricultural activity in the Funnel Beaker Culture (TRB, Neolith, about 3900 cal BC). Apart from the Neolithic colluvium and proluvium, only colluvia accumulated during the last millennium were found. The presence of Bronze Age colluvium remains a possibility. OSL dating confirmed a strong link between the increase in prehistoric farming activity and the growing intensity of Holocene water erosion. It also revealed the presence of colluvial sequences of erosion gaps, with the geologic record obliterated by later pedogenic processes, and impossible to identify on the basis of classical macroscopic and micromorphological analyses. The study has also shown that the OSL method is an important tool in chronostratigraphy of the Holocene colluvia as long as it is supported by deep paleo-geographical analysis of the entire basin and knowledge of colonization history. This method is not suitable for dating gully erosion sediments - thus the age of the oldest Neolithic gully erosion deposits in Bronocice was determined on the basis of dating of the overlaying colluvia.