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Application of malacological analysis to reconstruct climate fluctuations and human activity during the Middle and Late Holocene. Research in the valley of the Grajcarek stream (Pieniny Mts., southern Poland)

Alexandrowicz Witold Paweł

Acta Geologica Polonica

2023

Vol. 73, no. 1

85--102

The scope of this analysis included fluvial sediments of the low terrace of the Grajcarek stream in the Małe Pieniny Mts. (Western Carpathians). The structure of the terrace has been surveyed in five profiles. The sedimentary sequence includes alternating layers of gravel and calcareous mud with a maximum thickness of up to 2.2 m. A rich and varied malacofauna has been found in the mud. The age of the sediments was determined using the radiocarbon method. The sediments that make up the terrace cover the younger part of the Middle Holocene and the entire Late Holocene. The analysis of the malacofauna has allowed for the characterization of environmental changes. The most important of them dates back to the Middle Ages and is associated with the phase of intensive settlement in the Pieniny Mts.. It is indicated by deforestation and the related change in the composition and structure of malacocoenoses manifested by the replacement of forest communities by ones with open-country species. Gravel horizons are records of flood periods correlated with wet climatic phases. It is possible to distinguish six such phases covering the following periods: 6600–6100 y cal BP, 5500–5100 y cal BP, 4500–4100 y cal BP, 3200–2300 y cal BP, 2000–900 y cal BP and 400–200 y cal BP. They correspond to the periods of increased fluvial activity of rivers, intensification of mass movements, advances of alpine glaciers and the increase in the water level in lakes.

Record of environmental changes and fluvial phases in the Late Holocene within the area of Podhale (the Carpathians, southern Poland) : studies in the Falsztyński valley

Alexandrowicz Witold Paweł

Geological Quarterly

2019

Vol. 63, No. 4

629--642

The Falsztyński valley, in the eastern part of Podhale, Poland includes a low terrace spanning the stream channel, the structure of which has been studied in nine profiles. Five gravel levels and five mud levels with plant and abundant mollusc remains are described, temporally constrained by ten radiocarbon dates. The terrace deposits represent the terminal part of the Atlantic Phase and all of the Late Holocene. The mollusc analysis helped identify phases of environmental change, notably one in the Middle Ages connected with intensive settlement activities in the area of Podhale. These include deforestation, affecting mollusc communities with replacement of forest assemblages by open-country species. The gravel levels records increased fluvial activity periods correlated with humid climate phases. It is possible to distinguish five such periods corresponding to the transition of the Atlantic and Subboreal phases, the middle part of the Subboreal Phase, the transition of the Subboreal and Subatlantic phases, the younger part of the Subatlantic Phase, and the last 200 years. These correspond to the periods of increased fluvial activity in the valleys of other Carpathian rivers.