Włodzimierz Margielewski

Progress in the holocene chrono-climatostratigraphy of Polish territory

The Holocene delivers a unique possibility to establish climatic stratigraphic boundaries based on detailed chronostratigraphy reflected in various facies of continental sediments, in their lithological parameters and organic remains. These sediments are dated by the 14C method in the case of organic remains, by counting annual laminations in lacustrine facies, and by dendrochronological method in the case of fluvial sediments.The existence of well dated profiles enables to reconstruct various climatic parameters like amplitudes of seasonal temperatures, types and frequency of extreme rainfalls and floods and, finally, to distinguish rare rapid changes and most frequent gradual ones. This reconstruction is based on the analogous effects of various types of present-day rainfalls.The current authors present a critical review of existing chronostratigraphic divisions starting from simple millennial division by Mangerud based on Scandinavian palynological stratigraphy of peat-bogs and Starkel’s concept based on fluctuations in rainfall and runoff regime reflected in fluvial and other facies of continental deposits.In the last decades, the calibration of 14C dates allowed a new approach to be used for the construction of the probability distribution function of these dates in various facies or types of sediments, which formed a background for distinguishing and correlating climatic phases and defining boundaries between them. These approaches have been creating new opportunities for revision of the existing chronostratigraphy.The aim of this paper is to present a revised version of chronostratigraphic division based on climatic fluctuations reflected in various facies of sediments on the territory of Poland and discuss their correlation with other European regions and global climatic changes.

Crevice-type caves as initial forms of rock landslide development in the Flysch Carpathians

Crevice-type caves, formed along joints, are very common in the Polish Flysch Carpathians (more than 600 have been recorded). The caves represent accessible parts of the widened cracks, which are basic, initial forms of development of deep-seated rock landslides. Structural features of four selected caves (situated in different parts of the Carpathians) were studied in order to determine relations between joint systems and landslide formation. The studies prove that the main rock scarps often represent effects of earlier propagation of the cracks (=cutting surfaces) due to loading and unloading shearing stress. The cracks are structural forms developed along joints or faults. The cutting surfaces represented by cracks (caves) develop a long time before the main gravitational mass movements, whereas the sliding surfaces (shearing zones) are formed or significantly modified ad hoc during the gravitational transport of rock masses. Occurrence of the deep initial cracks causes modification of shape of the sliding surfaces, which are noncircular. The mountain slopes cut by many cracks are permanently developed. Thus, the periodic increase of activity of external factors (floods, downpours, earthquakes, etc.) leads to common formation of the landslides earlier prepared by crack development. This model of slope evolution enables us to interpret the occurrence of the landslide phases (in the Holocene) during which increasing of frequency of the landslides is observed.

Record of the meso- and neoholocene palaeoenvironmental changes in the Jesionowa landslide peat bog (Beskid Sądecki MTS. Polish Outer Carpathians)

The paper presents an analysis of depositional sequences of landslide peat bog situated in the depressions developed within the landslide landforms Jesionowa in the Beskid Sądecki Mts. (Outer Carpathians). The peat bog, with depositional sequence 2.80 m long, started to form at the beginning of the Atlantic Phase ca. 6390–5910 cal BC. Palynological and lithological analyses as well as several (14) radiocarbon age determinations of different horizons in the sediments enabled the reconstruction of palaeoenvironmental changes during the Meso-and Neoholocene. The increase in climate humidity at the beginning of the Subboreal and Subatlantic Phases was observed as delivery of minerogenic material to the peat bog basin and formation of a mineral horizon and an illuvial level within the peat. The particularly intensive delivery of allochthonous material to the peat bog took place at the beginning of the Subboreal Phase and was the result of both significant humid climate and increased human impact (colonization of the Funnel Beaker Culture) in the landslide area. Similar influence of younger colonisations of landslide area (Przeworsk Culture and, later, Valachian colonisation) was also recorded within the deposits of peat bog (illuvial and mineral horizons) in the early Subatlantic Phase. Rejuvenation of the landslide zone and formation of the younger landslide were connected with the increase in climate humidity at the beginning of the Subboreal Phase. The peat bog deposits situated within this younger landslide, which are ca. 1.8 m thick, are significantly contaminated with mineral material.

RECORDS OF THE MIDDLE - AND LATE HOLOCENE PALAEOENVIRONMENTAL CHANGES IN THE PCIM-SUCHA LANDSLIDE PEAT BOGS (BESKID MAKOWSKI MTS., POLISH OUTER CARPATHIANS)

Records of the Middle - And Late Holocene Palaeoenvironmental Changes in the Pcim-Sucha Landslide Peat Bogs (Beskid Makowski Mts., Polish Outer Carpathians) The paper presents analysis of depositional sequences of two peat bogs situated in the depressions developed within the landslide landforms Pcim Sucha in the Beskid Makowski Mts. (Outer Carpathians). The older peat bog, with depositional sequence 3.75 m long, started to form at the decline of the Boreal Phase ca 7570-7330 cal BC. Palynological and lithological analyses as well as numerous (18) radiocarbon datings of different horizons in the sediment enabled reconstruction of palaeoenvironmental changes of the Middle and Late Holocene. Increase in climate humidity at the beginning of the Atlantic, Subboreal and Subatlantic Phases were observed as deliveries of minerogenic material to the peat bog basin and formation of illuvial and mineral layers within peat. The particularly intensive delivery of allochtonous material to the peat bog took place at the beginning of the Subatlantic Phase and was the result of both significant humid climate and increased human impact (colonization of the Przeworsk Culture) in the landslide area. Rejuvenation of the landslide zone and formation of the second landslide were connected with this period and processes. Deposits of peat bog situated within this younger landslide, which are ca 1.3 m thick, are significantly contaminated with mineral material.

Recent Landform Evolution in the Polish Carpathians

The key drivers of relief transformation in the Polish Carpathians (the best studied region of the Carpathians) have been local downpours, continuous rainfalls, and rapid snowmelt. Threshold values are quickly exceeded during such events and powerful morphological processes are initiated. However, due to human activities, geomorphic processes are often accelerated and intensified with serious consequences. Thus, increased human impact is a key factor in the recent geomorphic evolution of the Polish Carpathians. Over the last two centuries deforestation, intensive agriculture, mining, housing developments on slopes, channelization of streams, and construction of reservoirs all have contributed to changes in the rate of the particular geomorphic processes. The intensity of sheet erosion depends on vegetation cover, land use, and cultivation techniques (terracing, contour tillage, crop rotation, etc.). Slopes bearing poorly constructed infrastructure have become susceptible to mass movements. At higher elevations debris flows, dirty avalanches, and extreme floods are crucial in slope evolution. Over the last 20 years the ratio of agricultural land and the rate of sheet erosion and deflation have decreased, while gully erosion on slopes and the incision of river channels have intensified and the reactivation of shallow landslides has become more common. Increasingly frequent extreme weather events may reverse the stabilizing trend of landform evolution.

The reflection of human activity in the sediments of Iwankowskie Lake from Subatlantic Phase (Polish Outer Carpathians)

The paper presents the analysis of organic and mineral sediments filling the depression, which developed over the landslide located at the slope (767–773 m a.s.l.) of Lubań ridge decscending to the Ochotnica river valley in the Polish Flysch Carpathians. The landslide formed in an early stage of the Subatlantic Phase (2490 ± 35 BP). The top of peat is dated at 1360 ± 50 years BP and is covered by 72 cm of clayey silts with some sandy intercalations, which indicate slopewash after deforestation. The pollen of ruderal plants and Cerealia (undiff.) reflect agricultural activity in the surroundings. The fragments of charcoal indicate the age of the forest clearance to the first half of the 17th century. The late forest clearance at the elevated north exposed slopes followed 200–300 years later in relation to the foundation of the village at the valley floor.

The development of gravitational caves versus periods of mass movement intensification during the humid phases of the Late Glacial and the Holocene: study of dated speleothems and slope deposits (Polish Outer Carpathians)

Mass movements have been one of the most efficient processes controlling the morphogenesis of the Outer (Flysch) Carpathians. Dated by 14 C method 180 landslides and related processes in the Polish Carpathians enabling to reconstruct mass movement chronology, confirm the thesis formulated by Starkel (1966), that the periods of acceleration of gravitational processes during the Late Glacial and the Holocene were connected with the stages of climatic humidity growths (Alexandrowicz, 1996; Margielewski, 2006; Starkel et al., 2013). Gravitational slope failures have often generated formation of non-karst caves. In the Polish part of the Outer Carpathians ca. 1400 caves, mainly of gravitational origin, have been explored up till now (Klassek, Mleczek, 2015). Part of these caves formed in the initial stage of landslide development, some ones formed during subsequent stages of landslide evolution (Margielewski, Urban, 2003; Lenart et al., 2013). Radiocarbon datings of speleothems allow us to reconstruct the stages of cave development and related mass movements. Pollen analysis of speleothems confirms these datings (Urban et al., 2015)