Search

In Eastern Europe Marine Isotope Stage (MIS) 3 represents a period characterised by severe climate change of very rapid onset, which is recorded in the regional sedimentary record. Hitherto this work, the geomorphic impact of these abrupt changes to NE Poland's 1st-order-stream valleys has been under-represented in studies. Here the combined results of lithological, geochemical, and palynological analyses—coupled with sediment OSL dating—demonstrate that MIS 3's earlier events (60–45 ka) mark an interval when contemporary dry valleys functioned as active stream corridors, places where deep fluvial incision had occurred. Prior to this MIS 3 fluvial activity there is an observed depositional hiatus encompassing sediments from MIS 5d to the oldest part of MIS 3. Valley-bottom sediment accumulation began ~44–40 ka, commencing at a time when shallow water reservoirs began to function. The resultant mineral infill is devoid of calcium carbonate and organic matter (OM). This sedimentation occurred under dry and cold climate conditions—i.e. under the influence of permafrost aggradation. The geochemical composition of the MIS 3 deposits indicates that environmental conditions are deteriorating. In effect, calcium carbonate was completely removed from the deposits, which resulted in the reduction of mobile elements (such as Na), removal of selected soil horizons, and an increased content of immobile elements—e.g. sedimentary Al, Rb, Ti. These processes are confirmed in the study sediments by magnetic susceptibility analysis. Here, in MIS 3 lake deposits, the presence of fissure structures filled with grey clay or fine sand is a common feature. Climatic changes during MIS 3's younger part were reflected in the slight increase of OM, which in turn increased the contribution of mobile, immobile, and trace elements. Most likely these change intervals represent more humid conditions during MIS 3. Sediment-trapping lakes within dry valley bottoms completely disappeared by ~30 ka.

Deep-seated relict permafrost was identified in borehole Udryn PIG-1 (north-eastern Poland) at depths from +450 to 357 m. In potential its extant provides an opportunity to expand the known effective realm of grain weathering. Specifically, uncertainty exists as to whether or not glacial-period frost weathering could even occur at such considerable depths, which is well outside an active-layer range (i.e., beyond the currently acknowledged domain of grain weathering). Sand deposits collected at a 410.70–396.75 m depth were subjected to grain-size analysis, then 0.5–0.8 mm quartz-grain surfaces were analysed under stereoscopic and scanning electron microscopy. The obtained results indicate that these relict-permafrost grains were both mechanically and chemically weathered. Mechanical weathering of quartz grains is identified as P- & F-type weathering. The former is associated with an increase in stress generated both by overlying ice-sheet masses and permafrost degradation. Here mechanical weathering was facilitated by the presence of well-sorted sediment, rounded or well-rounded grains, and high porosity. Its effects are microtextures such as breakage blocks and conchoidal fractures. F-type weathering is/was generated by freezing water in various sorts of cavities and cracks. Weathering is directly associated with the presence of permafrost at this depth. Additionally, chemical weathering is recorded on quartz-grain surfaces in the form of a ragged discontinuous coating. It has been proven here that weathering of quartz grains is not just a near-surface phenomenon, but also occurs deep below Earth's surface.

This study provides a new stratigraphic and palaeogeographic scheme for the time span between Marine Isotope Stages (MISs) 8 and 6. Based on detailed sedimentological and palynological studies, the...

Vegetation changes were documented across the last interglacial period (MIS 5e, Eemian) and continuing through the older part of the last glacial period (MIS 5d–a, early Weichselian). This study was based on pollen data collected at the Jałówka site, NE Poland. Two cold oscillations appeared within warm periods during this stage of the upper Pleistocene. The older oscillation was the temporary intra–interglacial cooling at the end of the Eemian. The younger one was the intra–interstadial cooling that occurred within the oldest interstadial of the early Weichselian (MIS 5c, Brørup). This last event corresponds well to the stadial separating both the Amersfoort and Brørup sensu stricto interstadials in the Netherlands and to the Montaigu event as recognized in France. The development of a pollen sequence allows speculation as to potential correlations with Greenland ice cores and marine records. We suggest that the Eemian in NE Poland may comprise not only MIS 5e, but also a part of MIS 5d. This supposition could shed light on potential for non-synchrony in upper boundaries of the MIS 5e and terrestrial Eemian in Europe. We await the development of more precise independent dating controls to validate our theory more assiduously.

Frost weathering affects rocks and/or sediments not only in the areas underlain by permafrost, but wherever cyclic temperature changes around 0˚C are recorded. One of the main parameters influencing the intensity of frost weathering, both in the macro- and micro-scale, is the number of freeze-thaw cycles (FT). It depends on e.g. profile depth, lithology, land cover and especially, on climatic conditions (e.g. Matsuoka, 2001; French, 2007). Nowadays, global climate changes lead to the gradual increase in the number of FT and thickening of active layer. This is especially common in high latitude areas. Spitsbergen is a proper example of an area where prevalent frost weathering is coupled with significant climate changes. The subject of the research is micro-scale frost weathering of sand-sized quartz grains, collected from the active-layer deposits of the Kaffiøyra Plain. Kaffiøyra is a coastal plain located in northwestern Spitsbergen (Oscar II Land), the largest island of the Svalbard archipelago. The thickness of the active layer recorded on the Kaffiøyra Plain varies both in space and time, with the maximum values observed in the summer season. However, its increasing in recent years has already be proven. Five profiles of sediments of different origins were analyzed with regard to their lithological variability. These included: moraine (from Little Ice Age - LIA), lake sediments and raised marine terraces. The analysis of the surface micro-relief of the sand-fraction quartz grains was performed using a scanning electron microscope (SEM). Additionally, grain-size distribution of samples, their pH, CaCO3 content and conductivity were analyzed to specify the intensity of frost weathering. It was proven that the most intense weathering takes place in the upper- and bottom parts of the active layer. In the first case, it could be the result of a great number of FT affecting the sediments, while in the latter, it was supported by the content of water, which accumulate on the upper part of permafrost. Moreover, paleobottom of ancient active layer was recorded within the contemporary active layer deposits at a depth shallower than its current position. Quartz grains from this paleobottom shows a clear increase in the number of microtextures resulting from frost weathering. Furthermore, there is a clear dependence of the intensity of frost weathering on the lithology of sediments, and the finer the sediment, the more intense the weathering. Regardless of the lithology, profile depth and pH, the frost weathering remains at its initial stage, that is emphasized by the dominance of frost-induced microtextures, such as small- and large-sized conchoidal fractures. Frost microtextures indicating a more advanced weathering process, i.e. small- and large-sized breakage blocks, are of a minor nature. The only exception is the bottom part of the active layer, where the greater number of frost microtextures, including large-sized breakage blocks, is recorded each time. REFERENCES:FRENCH H. 2007. The periglacial Environment. Third Edition.MATSUOKA N. 2001. Microgelivation versus Macrogelivation: Towards Bridging the Gap between Laboratory and Firld Frost Weathering. Permafrost and Periglacial Processes. 12. p. 299-313.

Climate variability may have played a significant role in the rise and collapse and reorganisation of many ancient civilizations. Such changes had a particularly strong impact on the political and cultural development of societies inhabited various parts of the Middle East during the first millennium BC. In this context, the South Caucasus, located on the Middle Eastern border zone, belongs to the most attractive areas for multidisciplinary research in the field of climate geology and archaeology.Metsamor is a fortified protohistoric settlement located in the bottommost part of the Araxes valley (S Armienia). Results of geological survey coupled with interpretation of archaeological and palynological data collected at the study area, indicated great climate fluctuations which could impact the life of local community. These fluctuations were identified with 2.7 ka climatic event based on the age dating and detailed stratigraphy of sediment at the study site. According to Singha et al. (2019), the interval between ~ 2800 and 2690 yr BP is considered as one of the wettest period in the Near East over the past 4000 years. It was followed by a ~ 125-years period of aridity interval. Transition from wet to dry climate conditions is referred to as a 2.7 or 2.8 ka BP event. From the archaeological perspective, its impact on Metsamor can be found in the record of various processes related to gradual abandonment of the settlement, and changes in the subsistence economy of its inhabitants. As a consequence, their livelihoods shifted from agriculture to cattle and goat breeding.This work was supported by the National Science Centre Poland. Grant no. 2018/29/B/HS3/01843.

Calcite cements are found within the glaciotectonically-deformed coarse-grained glaciofluvial sediments of the Saalian age (MIS 6) at the Koczery site (E Poland). Their sedimentation was controlled by the occurrence of permafrost (Mleczak et al., 2021). Under these conditions, aggradation rate of a glaciomarginal fan was high, and freezing of freshly-deposited sediments was relatively quick. Advancing ice sheet deformed these frozen glaciofluvial sediment in its foreland, creating single faults along with gently and tight folds. These deformed sediments were covered with a subglacial till creating a dome-like shaped landforms reassembling a Cupola hill. This calcite-cemented conglomerate occupies the uppermost part of coarse-grained glaciofluvial sediments. Its thickness ranges from 0.02–0.05 m up to 0.70 m and depends on the inter-limb angle of folds. The higher the inter-limb angle of folds, the thicker the conglomerate. Its greatest thickness is generally recorded on the lee side of major bed obstacles, i.e. glaciotectonically-deformed folds, in this case.Precipitation of calcite within the glaciotectonically-deformed glaciofluvial sediments resulted from a progressive freezing of the basal water film that occurred on the side site of deformed structures. The water froze due to the drop in water pressure on the lee site of folds, which in turn led to the precipitation of calcite. The results of oxygen and carbon stable isotope studies (δ18O, δ13C) indicate limestone clasts embedded in the glaciofluvial deposits as the source of carbonates involved in the cementation process (δ18O from -6 to -3‰ V-PDB, δ13C – from -1.4 to +0.9‰ V-PDB). Two types of calcite cements were recognized in the studied conglomerate. Each of them is thought to be a record of different basal conditions during the ice-sheet advance. The precipitation of sparite cement took place during the early stages of freezing under open-system conditions (i.e. continuous flow of water within the film). Micrite cement which overlies the sparite one was precipitated during the final freezing under closed-system conditions (i.e. water flow in the film is dominated by locally produced water involved in the regelation sliding proces; Sharp et al., 1990). Moreover, it is known that micrite precipitates from water which is more supersaturated with respect to calcite than that from which sparite precipitates.A thin (up to 1 mm thick) manganese-rich layer was registered between the layers of sparite and micrite cements. The precipitation of calcite is characterized by δ18O and δ13C values ranging from -6.9 up to -6.2‰ (V-PDB) and from -9.0 up to -5.5‰ (V-PDB), respectively. No significant differences in the isotope notation between micrite and sparite were observed, which clearly indicates similar parameters of the host water. Mleczak, M., Woronko, B., Pisarska-Jamroży, M., Bujak, Ł., 2021. Permafrost as the main factor controlling the fluvial sedimentation style on glaciomarginal fans. Sedimentary Geology. 422, 105971. https://doi.org/10.1016/j.sedgeo.2021.105971Sharp M., Tison J.L., Fierens G., 1990. Geochemistry of Subglacial Calcites: Implications for the Hydrology of the Basal Water Film. Arctic and Alpine Research, 22, 2, 141-152.

Recognition of quartz-sand grain shape, particularly its roundness and sphericity, is essential in reconstruction of sedimentary settings, transport conditions, duration of transport and post-sedimentary weathering. It is assumed that in currents environments (e.g. aeolian, fluvial) the increasing transport duration is reflected in progressively higher degree of roundness and sphericity of quartz grains. Furthermore, during transport, grains are gradually reduced to similar size and similar roundness; this leads to the accumulation of sediments with similar grain size distributions in differing environments. However, the question still remains: to what extent is the shape of a grain is the result of processes in given environment (e.g. aeolian or fluvial) and how much of its shape is inherited from other environments. The description of shape is subjective and reduction to a mathematical formula is time-consuming and in many cases impossible to apply (e.g. in field studies). One of the solutions is the automatic analysis of particle shape using the Morphologi G3SE. This study aimed to verify the efficacy of automatic image analysis (AIPS) in discerning quartz sand grain shape and associated sedimentary settings. Quartz grains (0.8-1.0 mm) from three sedimentary environments: angular, fresh grains (GNU) and aeolian (GRM) and fluvial grains (GEL) and with similar degree of roundness (well and very well rounded) were analyzed in terms of four shape-description parameters: Circularity High Sensitive (Circularity HS); Convexity; Solidity; Aspect Ratio. Next, principal component analysis (PCA) and discriminant analysis were applied to the obtained AIPS data. The parameter that best distinguishes the shape of GNU, GRM, and GEL grains is Circularity HS, associated with the degree of roundness, whereas Aspect Ratio was useful for analysing the degree of grain sphericity. The GRM and GEL grains with a high degree of roundness and either low or high sphericity should be characteristic for a long-term reworking by aeolian and fluvial processes. The presence of grains with low sphericity and high roundness in the environments where saltation transport prevails indicates that their shape has been inherited. Such grains require special attention to the Aspect Ratio values. Detailed analysis of grain features - such as sphericity and roundness enables accurate interpretation of transport environments in terms of transport duration and sediment maturity.

Sand-sized (0.5–1.0 mm) grains of mechanically-crushed vein quartz were subjected to the frost action under controlled, laboratory conditions. Defined temperature changes from -5˚C up to +10˚C provide cyclic freeze-thaw (FT) process, and thus simulate periglacial conditions. A total of 1000 FT cycles were simulated under low (213 mg/l) and high (1954 mg/l) water-mineralization conditions (LMW, HMW, respectively). Microtextural analysis of grain surfaces was undertaken using SEM (scanning electron microscope) before experimental run (0 FT cycles, i.e. reference sample) and after 50, 100, 300, 700 and 1000 FT cycles. Each time twenty randomly selected grains from each sample were analysed at low (~100-150x) and high (~1000x) magnification. The frequency of occurrence of individual microtextures on grains from a given sample was estimated, and frost-induced imprints were counted on each grain. The degree of surface coverage with a precipitated crust was determined qualitatively (low/high) and its elemental composition was determined by EDX (Energy-dispersive X-ray spectroscopy).The results of this experimental simulation indicate that four mechanical microtextures can be considered as diagnostic ones for the frost weathering process. These are: small- and large-sized conchoidal fractures (cf, CF, respectively) along with small- and large-sized breakage blocks (bb, BB, respectively). Two predominant outcomes in the course of micro-scale frost weathering have been identified: a) a physical aspect of the process evidenced by numerous cf, CF, bb, BB microtextures during first 300 FT cycles; followed by b) a chemical aspect resulting in the precipitation of surficial crusts and obliteration of grain microrelief. The complexity of frost-originated microtextures and their location on grain surfaces reflect three stages in the evolution of frost-induced microrelief: 1 – initial, development of CF, 2 – progress, development of cf, and 3 – advanced, dominated by bb and BB growth; summarized as: crack → CF → cf → bb → BB. This evolution may, however, be influenced and interrupted by the grain refreshing process, when cracking and detachment during the formation of CF reveal the fragments of fresh, unweathered surface of grain. This frost-induced refreshment causes the grain to lack some / most of the mechanical frost-originated microtextures. It may occur many times at each stage (1, 2, 3) of the weathering process and the cycle of development of frost-originated microrelief (crack → CF → cf → bb → BB) is thus repeated. The term ‘renewal of frost weathering’ has been introduced here for this event. The obtained results indicate that microtextural characteristics of frost-weathered grains depends largely on the mineralization of water involved in the process. It seems that frost weathering of the quartz grains enveloped with HMW is more effective than of these poured with LMW.Acknowledgements. The project is financially supported by the National Science Centre Poland. Grant No. 2019/33/N/ST10/00021.

Aeolian dune field pattern could provide a very detailed image of the influence of environmental controlling factors (wind regime, topography, sediment supply and others) to its development. Moravian Sahara dune field located in Southern Moravia, Czechia, and thus far away from the European Sand Belt (i.e. the area of major aeolian accumulations in Europe), represent a unique archive reflecting the effects of these variables. Even despite its remoteness from the Fennoscandian Ice Sheet during the Last Glacial Maximum, the permafrost occurred in Southern Moravia, and thus periglacial processes operated here. Different approaches including LiDAR DTM analysis, ground-penetration radar (GPR), and near-surface wind modelling were applied to investigate the role of the controlling factors. Two groups of differently oriented periglacial-related dunes (ENE-WSW and N-S) have been distinguished via the DTMs, suggesting a significant twist in atmospheric circulation connected with the retreat of the Fennoscandian Ice Sheet after the Last Glacial Maximum. Beside that, a strong influence of the local topography to the modification of the wind flow and the possible sediment sources were distinguished and described. Furthermore, confrontation of the reconstructed palaeowind directions with the modelled atmospheric circulation during the Weichselian and the OSL ages of aeolian sediments enabled the temporal assignment of the Moravian Sahara dune field development to the Late Pleniglacial and Late Glacial periods. Thus, our results show their applicability to the very detailed study of the influence of environmental conditions on the development of the cold-climate aeolian dune fields.

The research conducted in recent years has revealed that processes operating at depth play an important role in the morphogenesis of stepped tablelands in Central Europe (SW Poland, N Czechia), underlain by alternating layers of sandstone and fine-grained rocks of the Upper Cretaceous age. It has been demonstrated that underground erosion significantly contributes to the in situ disintegration of the marginal parts of sandstone plateaus and mesas, thereby producing distinctive ruiniform assemblages. They comprise chaotic boulder clusters replacing the cliff-lines, joint-aligned corridors, clefts opened due to the loss of mass from beneath, as well as plazas and courtyards with negligible surface runoff. While the widespread occurrence of sandy cones at the outlets of vertical fissures and allochthonous sandy aprons on the subjacent slopes testifies well to the efficiency of underground erosion, the mechanisms of detachment of sand grains remain unknown. This research aims to elucidate which processes are making the sandstone mechanically incoherent and susceptible for mechanical erosion at depth.In older views weathering processes acting upon sandstone cliff-lines have either remained unspecified or a priori assumed to be mechanical breakdown. Yet, the presence of joint-aligned and highly disintegrated zones, often mimicking the grikes of the ‘classic’ karst terrains, as well as the widespread evidence of sandy detritus removal via subsurface drainage, allowed us to hypothesise that dissolution may be an important but neglected factor responsible for the loss of coherence of the sandstone rock mass.Sandstone samples were collected from both disintegrated and non-disintegrated sandstone cliff-lines, as well as fresh debris originating from a recent rockfall event in one of the rock cities in Czechia. Loose grains of sand, already removed from the caprock and deposited at the foot of rock walls, were investigated too. Scanning electron microscopy equipped with energy dispersive spectrometer (SEM-EDX) was used to study micromorphological changes, diagnostic of intensive chemical weathering. This was supplemented by studies using the polarizing light microscopy, i.e. study of thin sections as well as x-ray diffraction (XRD) accompanied by thermal analysis (DSC-TG) to evaluate mineralogical composition of sandstone and to assess the secondary rock porosity.The preliminary results revealed high degree of etching, mainly of syntaxial quartz overgrowths, with a number of v-shaped or irregularly shaped pits as well as large embayments. Interestingly, SEM-EDX analysis showed the presence of kaolinite, which might conform to the advanced chemical weathering of sandstone as well. It is supposed that solutional processes not only have prepared the rock for further erosional processes and the resultant development of ruiniform relief, but they also contribute to a variety of catastrophic mass movements due to the significant decrease of intact rock strength.The results presented are the first outcomes of the new Q-MESA project (no. 2020/39/D/ST10/00861) funded by the National Science Centre, Poland.

Till macrofabric and grain-size analysis of glacial diamictons and landforms present in several valleys of the Serra da Estrela Mountains in central Portugal were used to interpret till types and to reconstruct the glacial paleoprocess history of this mountainous region. Supraglacial melt-out and flow tills are dominant in this range. Supraglacial melt-out tills, representative of periods of glacial stability and stagnation followed by recession, present weaker fabric data and coarser, poorly sorted sediments. Flow tills, mainly representative of glacial stability followed by recession, present crude layering, and soft-sediment deformation structures with moderate fabric data and coarser to fine, poorly sorted sediments. Glacial diamictons affected by post-glacial paraglacial activity in the form of landslides were also observed in three valleys. These present weaker to moderate fabric data and coarser, poorly sorted sediments. These glacial diamictons and landforms are of particular importance in the reconstruction of the glacial dynamics and history of the Serra da Estrela Mountains due to a scarcity of chronological data based on absolute dating methods. These mountains also represent the southernmost Atlantic range in Europe where significant glaciation took place, which makes it an interesting area to investigate mountain glacial dynamics in low elevation humid Atlantic coastal ranges and compare it with other Atlantic ranges.

A correlation of stratigraphic subdivisions of the late Middle Pleistocene (MIS 12-6) in central Europe is extremely difficult, because of abundant hiatuses. Therefore, the site Rechitsa in western Belarus is extremely important for a regional stratigraphy, because of its well documented sediments of the Alexandrian Interglacial (Holsteinian; MIS 11) and a crucial palaeoclimate and palaeoenvironmental record of the Middle Pleistocene. The sequence starts with proglacial delta deposits formed at the termination of the Berezinian Glaciation (Elsterian; MIS 12), overlain by organic deposits of the Alexandrian Interglacial (Holsteinian; MIS 11) and the early glacial cooling of the Pripyatian Glaciation (Saalian). The hiatuses in MIS 10, 9 and 7 are interrupted by occasional occurrence of a periglacial lake, accompanied with open vegetation communities in MIS 8, characteristic by alternate temperate and cold episodes with significant climate-induced environmental transformations with extremely cold and dry conditions recorded by huge frost wedges with primary infilling. Extremely severe climatic conditions of MIS 6 favoured development of huge frost wedges with primary infilling, overlain by sediments of a periglacial lake. The Rechitsa section was overbuilt by glaciofluvial and aeolian deposits during the Pripyatian Glaciation (Saalian). The recorded huge hiatuses in MIS 10, 9 and 7 are common in central Europe represent presumably arid conditions and lack of deposition. The sedimentary sequence at the site Rechitsa is an important link of central and eastern European stratigraphic subdivisions of the Middle Pleistocene.

Liquefaction can cause deformation of unconsolidated sediment, but specific processes involved and the trigger mechanisms often remain obscured. This study describes multiple deformed sediment layers in a succession of lacustrine sand, silt and clay deposited during the Marine Isotope Stage 5d in north-western Lithuania. The deformation structures (load casts, pseudonodules, ball-and-pillow structures, broken-up laminae and injections) are embedded in ten separate layers of fine-grained, laterally continuous sediments. Detailed mesoscale sedimentological analyses suggest that each deformation event consisted of numerous successive stages of sediment advection facilitated by liquefaction. Low-permeability fine-grained laminae contributed to localized pore-water pressure build-up and lowering of sediment strength. Erosional top surfaces that truncate layers with soft-sediment deformation structures suggest that at least seven deformation events were separated by successive periods of initial erosion and then uninterrupted deposition in the lake. The most likely trigger of the deformation was recurrent palaeoseismic activity possibly linked to a late glacial isostatic adjustment following the Scandinavian Ice Sheet melting after the Saalian glaciation. This study emphasizes the potential role of seismic processes in shaping the sedimentary record of the intraplate region of north-eastern Europe and contributes to constraining the depth of liquefaction, regardless of the actual trigger mechanism.

The study focuses on sand grain properties in different parts of a beach-dune system built entirely of heavy mineral particles. These properties are related to: (1) resistance of particular minerals to weathering and abrasion, (2) hydraulic sorting in the swash zone, and (3) aeolian sorting during grain transport inland from the upper beach. The main waterlain and windlain sand properties depend on settling velocity which results from grain density (reflecting grain mineralogy), size, shape and roundness. The study was performed on the beach and dunes at Patea on the west coast of the North Island of New Zealand, which are comprised of heavy minerals assemblage containing a ferromagnetic (dominated by titanomagnetite) and non-ferromagnetic (mainly pyroxene and amphibole) fractions. The result demonstrates that three zones of different sand properties can be distinguished: (1) a lower swash zone dominated by non-ferromagnetic, larger and more angular particles which are carried back from the upper swash zone down the foreshore by the backwash; (2) an uppermost swash zone and beach with almost 100% of ferromagnetic, smaller and more rounded particles deposited at the back of the beach by the uprush, which during high tide and storms can reach the cliff toe, and can be reworked by wind; and (3) a climbing dune composed of a more poorly sorted mixture of non- and ferromagnetic particles. In terms of both mineralogy and grain size and shape, the dune sand is less uniform than the beach sand. Aeolian segregation resulted here in sand textural features opposite to those found in dune sands composed of light minerals. The results highlight the density-dependent variability of grain size and shape of beach-dune deposits consisting of only heavy minerals, and broaden our understanding of mechanisms of sedimentary processes which is particularly important when reconstructing older sedimentary successions.

The aim of this paper is a critical verification of the late Middle Pleistocene stratigraphy in Poland in connection with stratigraphical schemes in the neighbouring countries. Although a terrestrial record of the Middle Pleistocene is almost complete in western and southern Europe, it is full of gaps in central and eastern Europe. Eight key sites in Poland and one in Belarus were selected to compile environmental and palaeoclimate data for a revised stratigraphy from the termination of MIS 12 to MIS 6, and the chronology was based on correlation with oxygen isotope stratigraphy and OSL ages. The late Middle Pleistocene record starts with the Holsteinian lake sequences, some of which have been initiated already at the end of MIS 12, persisted through MIS 11 and terminated in mid-MIS 10. In the examined sites, MIS 11 is represented also by deposits of meandering rivers in a temperate climate. In contrast, there is no evidence for deposition in most of MIS 10 and in MIS 9. A warmer and presumably wet episode at the beginning of MIS 8 lead to local erosion, followed by development of small lakes. Modest ice sheet advance into central Europe occurred in the second part of MIS 8, as reflected by a till, glaciofluvial and glaciolacustrine deposits and presumably, also by permafrost and ice wedges in western Belarus. MIS 7 seems to have been generally warm and wet when small lakes and meandering rivers could develop. Such mild conditions were interrupted with cool and probably drier episodes when braided rivers and limited pedogenesis occurred. Saalian ice sheet cover of central Europe in MIS 6 was widespread, but even more importantly, in this stage periglacial environments were dominant, as shown by continuous permafrost, intensive aeolian activity and development of ice wedges and involutions. Braided rivers developed during short wetter intervals.

The article presents the results of research on the formation conditions and the age of glaciogenic deposits left by the Scandinavian ice sheet in the Eastern Carpathian Foreland, in its part drained by the Dniester River and its tributaries (Black Sea basin). These deposits (till, erratics, glaciolacustrine and glaciofluvial sediments), preserved only in some places and occurring in the range of altitudes defined by terrace VI (Early Pleistocene) and terrace V (Middle Pleistocene), are the southernmost traces of the ice sheet in Europe. They are underlain by fluvial deposits and overlain by loess deposits, and locally occur as intraloess layers. The following research methods were used: geomorphological mapping, sedimentological, lithological, micromorphological, palaeopedological, and palaeontological analyses, as well as luminescence dating. The obtained results allowed a reconstruction to be made of the main stages of morphogenesis and the style of the ice-sheet advance at its maximum extent, defined as the Sambor Phase. The area was glaciated during MIS 12 (Elsterian II = Sanian 2 = Okanian), as indicated by the occurrence of a complete Middle/Upper Pleistocene loess–palaeosol sequence. The oldest palaeosol (S4), i.e. Sokal (=Mazovian = Zavadivka) soil that developed directly on the glaciogenic deposits or loess L5 is correlated with the Holsteinian (=Likhvinian) Interglacial (MIS 11).

An extraordinary variation of plastic and brittle deformation structures with periglacial, glaciotectonic and seismic features was observed within the unconsolidated, upper Pleistocene meandering river succession in the Slinkis outcrop in central Lithuania. Among these deformations, the following structures were described: (1) ice-wedge casts in the lower part of the sedimentary succession, linked to periglacial processes, (2) soft-sediment deformation structures, such as load structures (load casts, pseudonodules), flame structures and water/sediment-escape structures, all trapped in clearly defined layers in the upper part of the sedimentary succession, which are related to the propagation of seismic waves, and (3) faults occurring throughout the sedimentary succession, which are associated with glaciotectonic processes. To our knowledge, this is the first description and analysis of the combined presence of such a diverse range of deformation features caused by three trigger mechanisms in a meandering fluvial sedimentary succession.

Since the end of LIA climatic amelioration results in retreat of glaciers worldwide and the development of glacial forelands with freshly abraded rock surfaces undergoing weathering. When the timin...

Proxy data from pollen and mollusc indicator species, periglacial phenomena, changes in geometry of mountain palaeoglaciers and based on selected lithological and geomorphological features enabled reconstruction of the Late Pleistocene climate characteristics in Poland and adjacent areas. Climate during the Eemian was generally stable but with a distinct west-east gradient in summer. Strong influence of the Atlantic air masses moving to the east resulted in the annual precipitation over 600 mm. Climate instability in the late Eemian as well as during stadials and interstadials of the Early Weichselian was expressed by progressive cooling and increasing temperature difference between winters and summers, reflecting stronger continentalism towards the west, accompanied by decreased precipitation. Periglacial frost crackings and polygonal patterns indicated occurrence of permafrost in Poland already at about 49 ka BP and its occurrence until the termination of the last glaciation. These periglacial structures have developed at mean annual temperatures from −9 to −4 °C, with winter extremes up to about −25 °C. Mean summer temperature reached likely around 10 °C as suggested by palaeobotanic record. Palaeoglaciological studies of mountain glaciers across Europe allowed inferring their activity and sensitivity to climatic fluctuations during the Late Weichselian. The Weichselian of central Europe was controlled mostly by the southerly and easterly circulation dominated by climate cyclones and anticyclones, respectively. An inflow of air masses from the west was significantly limited and concentrated mainly within the so-called periglacial corridor between the Scandinavian ice sheet and the Alps. Such circulation pattern determined serious reduction of precipitation during the Last Glacial Maximum that reached 60% in relation to modern conditions. The following Late Pleistocene cold phases (Oldest and Younger Dryas) were slightly warmer and wetter with increasing contribution of the westerlies that were strongly dependent on progressing shrinkage of the Northern Hemisphere ice sheets.

The source of clastic material supplied to the epicontinental sea during the Middle and Late Jurassic in the Pomeranian Segment of the northern part of the Mid-Polish Trough is analysed, using deposits from the Rzeczyn PIG-1 borehole that represent the Łyna, Chociwel, Brda, Paluki, Kcynia and Rogoźno formations. Heavy mineral analysis, including weathering indices (ZTR, GZI, RZI and Q) and standardised scores for each mineral species, shows that each formation is characterized by a different heavy minerals association. In each association, transparent minerals include both ultrastable minerals (zircon, tourmaline and rutile), occurring in various proportions, and unstable minerals. This indicates that deposits subject to earlier multiple reworking were eroded from the surrounding landmasses. Most probably these deposits represented Triassic rocks, although fresh weathering covers were also eroded. The main direction of clastic material supply was from the N and NW, and to a lesser degree from the NE. The main reasons for changes in the source areas were probably sea level oscillations, while during regressions, exposed parts of the seabed became source areas of clastic material. Conversely, during transgressions, parts of the seabed became cut off from the supply of clastic material from eroded landmasses.

The objective of this work is to present a first assessment on the age of the glacial features of the Serra da Estrela, in the central Portugal, Iberian Peninsula (40°19′ N, 7°37′ W, 1993 m), using Cosmic-Ray Exposure dating (in situ cosmogenic 36Cl). A total of 6 samples were dated, 4 extracted from exposed moraine boulders and 2 from glacially polished bedrock surfaces. Despite the low number of samples, the results are consistent, reinforcing previous dating obtained by other methods and geomorphological and paleoclimatic information. The maximum extension of the glaciers occurred at the end of the Penultimate Glacial Cycle (Marine Isotope Stage 6), during Heinrich Stadial 11, around 140 ka. At the end of the Last Glacial Cycle, slightly before the Last Glacial Maximum, at around 30 ka, the Estrela glaciers reached again a similar extent. Finally, the glaciers disappeared from the Serra da Estrela at the beginning of the Bolling-Allerod Interstadial, at around 14.2 ka. These data confirm a certain synchronicity in the major glacial phases in most the Mediterranean and also European mountains, although there are notable differences in the maximum extent in the two cycles.

Loading processes and the resulting load structures induced by processes related to periglacial conditions are compared to those induced by seismic shocks. The load structures themselves are relatively easily recognizable but the responsible trigger mechanism is, though depending on the geological context, commonly difficult to establish. Load structures like load casts, pseudonodules, ball-and-pillow structures and flame structures are commonly ascribed to instable density gradients within sediments and to differential loading, but their formation always requires liquefaction. In glacigenic sediments, deformation structures have most commonly been ascribed to periglacial processes (as a type of cryoturbations), but it becomes ever more clear that glacigenic sediments can, particularly during ice-front fluctuations, be affected by faulting-related earthquakes (due to glacio-isostatic adjustment), and the thus triggered seismic shocks may result in deformations, including – most commonly – load structures. We inventory the evidence that may help to distinguish, on the basis of textural and structural features, load structures with a seismic origin from those that result from periglacial processes, taking into account that truly diagnostic criteria do not exist.

The paper focuses on analysis of macro‐ and micromorphological characteristics of relict slope deposits in Serra da Estrela (Portugal) to understand the significance of different slope processes and paleoenvironmental settings. Micromorphology is a useful sedimentology technique allowing significant advances compared to macroscopic techniques. Results show that different processes are involved in the development of the slope deposits, reflecting different environmental conditions. The main processes responsible for the emplacement of the relict slope deposits are solifluction, debris‐flow and runoff, but postdepositional changes are also present. Solifluction was identified in slope deposits between 650 and 1500 m a.s.l. The common microfeatures identified are circular arrangement of grains with a core grain, rounded vesicles, vertical grains, matrix deformations and fine‐grained deposits. Slope deposits above 1300 m a.s.l have a platy microstructure and coincide with the altitudinal range of the relict rock glaciers, indicating the elevation limit of permafrost. Below this altitude platy microstructures are less frequent. Slope deposits in north‐facing slopes were affected by frost‐induced processes in a seasonal frost regime, followed by a postdeposition illuvial phase. Debris‐flow and runoff were identified in slope deposits between 680 and 1260 m a.s.l. The common microfeatures are oblique grains, grain dumps, and coarse and fine grain lineations, and banded microstructures were identified in runoff processes. Debris‐flow deposits have a circular arrangement of grains without a core grain, identified in sediments in paraglacial and periglacial environments. The slope deposits show evidence of past periods of enhanced periglacial activity since the last glaciation until the Younger Dryas. (Less)

Significant quantities of ruptured pebbles are found in glaciotectonically deformed glaciofluvial sediments of the Saalian glaciation (MIS 6) at the Koczery site (E Poland). To identify the responsible mechanisms for the pebble-rupture activity, structural, petrographic, roundness and shape analyses were done. Additionally, till fabric of overlying glacial diamicton was analysed and compared to the other outcomes. The origin of fractures in ruptured pebbles of glaciofluvial sediments is directly linked to compressive stress caused by glaciotectonic processes because of 1) ruptured pebbles occur mainly in glaciotectonically deformed sediments (a quarter of all pebbles is fractured); 2) ruptured pebbles almost always occur one-by-one primarily in gravelly lithofacies; 3) fractures occur in pebbles derived from all petrographic groups; 4) fracture occurrence is independent of pebbles size, shape and roundness; 5) fractures mostly occur parallel to each other (along long ‘a’ or short ‘c’ axis of pebbles) and parallel to the bedding of lithofacies; and 6) in most cases broken fragments of ruptured pebbles survived in the host sediment indicating that the observed damage occurred in situ. This novel study of ruptured pebbles found in glacigenic environments sheds new light on the dynamics of glaciotectonic processes, and may be useful in the characterization of palaeostresses that occur during glaciotectonic deformations.

Formation of dunes in the Płock Basin of the Vistula River valley in Central Poland is connected with the aeolian processes that occurred within the European Sand Belt during the Late Pleistocene. Changes in sedimentation conditions, from fluvial (unit G1), to fluvio–aeolian (unit G2) then to aeolian (unit G3), were respectively recorded in the fluvioglacial terrace sand dune profiles in the village of Goreń Duży (the Płock Basin, Central Poland). Both fluvial and aeolian processes occurred in the periglacial zone of the last glaciation, the northern limit of which is defined by the Last Glacial Maximum (LGM), being 18.4 ka in the Płock Basin. River and ice-marginal valley terrace sand sediments, in association with glacial deposits, could be the source material for the studied aeolian bedforms. The results of morphoscopic analysis of dunal sand quartz grains indicate that rapid deposition occurred more often than did long-term longrange grain transport. Grain transport genesis begins during the Older Dryas, which is confirmed by optically stimulated luminescence (OSL) dating performed for unit G2: 13.06±0.76 ka and 13.54±0.84 ka. During dune formation, dead-ice blocks remained intact in a subglacial channel until the Allerød, which suggests that aeolian processes continued after block melting, throughout the Younger Dryas. Successional aeolian processes have resulted in the extensive dune fields of the Płock Basin.

The Neple site is located on a marginal moraine between the valleys of Bug and Krzna rivers in the southern part of the Polish–Belarusian border area. A glacial diamicton is overlain there by glaciofluvial sand and gravel. The glacial diamicton is laminated and, based on petrographic examination, it was ascribed both to the Sanian 2 Glaciation (Elsterian) and the Warta Stadial ice-sheet of the Odranian Glaciation (Saalian). The sediments were glaciotectonically deformed during readvance of the Warta Stadial icesheet. A local stress field was from the northwest and north but it partly encountered resistance from the glacial lobe located in the present-day river-mouth of the Krzna River. Similar glaciotectonic deformations are common also along the southwestern slope of the present Bug River valley, demarcating the maximum extent of the Warta Stadial (Saalian) ice-sheet in this area.

Well-rounded grains extracted from aeolian and subaqueous environments were analysed to determine a quantitative parameter describing the microtopographic surface properties of sand-sized quartz grains, expressed as a degree of smoothness or as an inverse roughness. To this end, the spectral method was used to calculate their fractal dimension values. Fractal characteristics and spectral fractal dimension (DS) were determined for a scanning electron microscope (SEM) image (560 × 560 pixels) obtained for each study grain. This parameter, (DS), describes the complexity of objects, which means that the higher its value, the more complicated the analysed grains are in terms of exterior roughness and surface microirregularities. The obtained results indicate that values of the parameter (DS) were higher for all aeolian grains compared to grains from either low- or high-energy subaqueous environments. This difference in results is attributed to the presence of microirregularities on the surface of aeolian grains, microtextures forms such as mechanically upturned. This parameter value increases as the energy of the aeolian environment increases. Values of (DS) for subaqueous environments grains correlated with the frequency of microtextures that resulted from high-energy grain-to-grain collisions (e.g., V-shaped percussion cracks), or from the chemical etching of the grain surface (e.g., solution pits, solution crevasses)—the higher the frequency of either collision or chemical-etching microtextures, the higher the value of the fractal dimension (DS). Thus, it has been demonstrated that fractal analysis can serve as a useful tool to discriminate between the analysed sedimentary environments, to assess a depositional system’s kinetic energy, and to compare the intensity of chemical weathering.

The emergence of the Pleistocene aeolian processes and their intensity was revealed through morphoscopy—the observation and analysis of quartz grain shape and microtexture. Sediments from 39 cored boreholes and three outcrops located in central and eastern Poland were analysed using methodology developed in 1942 by Cailleux to identify past wind action. This method is based on the recognition of the degree of roundness observed on quartz grains along with their surface typology (matt or shiny). The obtained results allowed us to separate seven distinct periods where the content of quartz grains with matt surfaces and varying degrees of roundness increased indicating the presence of an aeolian environment. These processes were different in their nature and intensity, with the wind-action periods varying from long-lasting and very intense (identified across the entire research area) to periods with low intensity and local wind-action events. These periods can be correlated with the advance of oldest glacials—the Narevian/Nidanian (MIS 36-34/MIS 22), the Sanian 1 (MIS 16) the Sanian 2 (MIS 12), the advance and retreat of the Odranian Ice Sheet (MIS 6, maximum stadial), and the Odranian Glaciation (MIS 6. post-maximum stadial [Wartanian]). These aeolian processes lead to the formation of coversands and fluvial sediments that are rich in aeolianized grains.

The studies were conducted in a dry valley in NE Poland. They were aimed at determining the origin of this structure and tracing the processes that have shaped the dry valley in a time span of about 130 ka. The research included detailed geological mapping, including piercing of a number of boreholes and electrical resistivity tomography (ERT) surveys. The obtained material was pollen analysed, OSL dated, and the grain size distribution and the morphoscopy of sand quartz grains were investigated; additionally the organic matter (OM) content was determined. Based on the obtained results it was concluded that the structure currently occupied by sediments of the dry valley was formed during the Warta Stadial of the Odranian Glaciation (Saalian; MIS 6) as a glacial tunnel valley. Small, probably isolated depressions functioned in the dry valley bottom after the ice sheet retreat. The sediments record a full succession of climate oscillations from the Eemian Interglacial (MIS 5e) (pollen zones E1 to E7) through the Early Vistulian (MIS 5a-5d) to MIS 4. In the Early Vistulian, the depressions functioned as lakes, or got shallower and were replaced by peat-bogs, depending on the climate conditions. During MIS 4, the bottom of the dry valley was subjected to erosion as a result of concentrated water flow. This caused draining of the existing depressions and their incorporation within the flow. Probably during MIS 3, solifluction was activated on the slopes of the dry valley. During LGM, permafrost aggradation occurred in the study area, recorded by two generations of epigenetic sand wedges and development of aeolian processes. In contrast to analogous processes within the European Sand Belt, the latter processes acted for a short time and only locally. The final record are Holocene soils. It seems that the analysed valley is a good example of palaeoenvironmental conditions in Eastern Europe.

This study describes the sedimentary successions of two glaciomarginal fans (=end moraines) deposited during MIS 6 and MIS 2 in the eastern and north-western part of Poland. Sedimentological analyses of the successions indicate they were both deposited close to the ice sheet margin and are dominated by extensive gravelly and sandy sheet beds derived from the upper flow regime with single ice-wedge structures. Qualitative and quantitative analysis of the pancake-like gravelly and sandy sediments was performed using Markov chain analysis. The presence of these, admittedly common, sedimentary successions raises two key points: why sheetfloods are so common on glaciomarginal fans instead of in-channel flows, and whether sedimentary rhythms deposited by sheetfloods represent the full depositional records, or only partial ones due to accompanying erosion. While both points remain unclear, the answers to these questions may be connected to the presence of permafrost, which occupied the foreland of the ice sheet where the glaciomarginal fans were deposited: it can control the type of proglacial river flows on glaciomarginal fans, the depth of erosion and influence the record of sedimentary rhythms.

Our paper describes and interprets grain microtexture and microstructure collected from periglacial sediments on the Abalakh High-Accumulation Plain (AHAP) in Central Yakutia. This territory occupies the Lena–Amga Rivers interfluve. In borehole 18/1, five sediment Complexes (I–V) of successive environments were recognized: 1) alluvial in the base of the borehole—Complex I; 2) alluvial-lake—Complex II; 3) lake-complex—Complex III; 4) ice-complex (yedoma)—Complex IV; and finally 5) a Holocene cover—Complex V. Quartz sand-grain and silt-grain microtextural analysis was undertaken in a scanning electron microscope (SEM) and supplemented by mineralogical analyses to reconstruct the sedimentary-accumulation environment, discern the influence of periglacial conditions on the grains, and identify the sediment source(s) for each complex. Based on the results, a conclusion can be reached that the accumulation of Complex I took place as a result of multiple repetitive transportation events recycling the same material and introducing a limited supply of new material into the fluvial environment. Upward in the succession, fluvial-process activities decreased in favour of lake-deposit accumulation. Frozen syngenetic ice-rich silty deposits—yedoma or ice complex—of Complex IV are composed of grains with a precipitated surface, but differ from the underlying deposits in the degree of crusting and mineralogy. Most probably aeolian processes are responsible for their transport. They include a variety of sediments, including older-sourced sediments such as retransported loess and the detritus from mechanical weathering coeval with sediment accumulation. Traces of frost and chemical weathering have been identified on the grain surfaces, the former visible in the form of breakage blocks and conchoidal fracture microtextures and the latter – as surface crusting. However, the frequencies of these microtextures are low, which suggests a relatively high rate of sediment accumulation.

Sand grains from Quaternary glacial, aeolian and fluvial deposits in the Mazovian Lowland, central Poland, were examined to characterize the effects of different Quaternary processes on sand-grain surfaces that experienced repeated cycles of intense polar-desert-like conditions during the Middle and Late Pleistocene. A cold, dry and windy periglacial environment prevailed here at least twice between the Saalian (Marine Isotope Stage (MIS) 6) and Holocene (MIS 1) stages. Because the surface characteristics of quartz sand grains can provide important palaeoenvironmental information, we examined grains extracted from sediment samples in different landforms to determine their surficial features from scanning electron microscope images. The grain surfaces were dominated by microtextures characteristic of aeolian-induced grain transformation, indicated by a high percentage of well-rounded, low-relief-worn grains with dish-shaped depressions, bulbous edges and upturned plates. Although remnants of previous sedimentary cycles were occasionally observed, aeolian effects were dominant even in glacial and fluvial settings. Quartz microtextures indicated that none of the examined grains represented their original setting, but rather suggested remobilisation under periglacial conditions. (Less)

The aim of the paper is to present general characteristics of the climate in Poland during the Vistulian (Weichselian), expressed by changes of its continentality during warm and cold intervals. This last glacial stage in Poland is commonly subdivided into Early Vistulian (MIS 5d-a), Lower Plenivistulian (MIS 4), Interplenivistulian (MIS 3), and Upper Plenivistulian and Late Vistulian (MIS 2). Main climatic features of this glacial stage could be reconstructed, based on compilation from published data concerning characteristics of glacial, fluvial and aeolian sedimentary environments, geomorphology, analysis of indicator plant species, Coleoptera, and geographical distribution of periglacial structures. These data were indicative especially for evaluation of mean temperature of the warmest and the coldest months but could be also helpful in determination of drier intervals and some aspects of general atmospheric circulation. Paleoclimatic characteristics of the last glacial stage from the territory of Poland were put into the European context. During the Early Vistulian in eastern Poland, higher continentality was characteristic for interstadials (Amersfoort, Brorup and Odderade), and was considerably lower during the intervening colder stadials (Herning, a cooling between Amersfoort and Brorup, Rederstall). Among the interstadials, the most continental climate occurred during Brorup (similar continentality as at present), considerably less during Amersfoort and the least during Odderade. A decreasing trend of continentality for the cold stadials of the Early Weichselian eastwards in Europe could result from a remarkably less dynamic Gulf Stream in the North Atlantic when the ocean was covered with vast sea ice during winters, whereas the adjoining continent was occupied by permafrost, and the atmospheric circulation was presumably driven also by the Scandinavian ice sheet.

Presented are the results of research into the fluvio-aeolian sedimentary succession at the site of Postolin in the Żmigród Basin, southwest Poland. Based on lithofacies analysis, textural analysis, Thermoluminescence and Infrared-Optical Stimulated Luminescence dating and GIS analysis, three lithofacies units were recognised and their stratigraphic succession identified: 1) the lower unit was deposited during the Pleni-Weichselian within a sand-bed braided river functioning under permafrost conditions within the central part of the alluvial fan; 2) the middle unit is the result of aeolian deposition and fluvial redeposition on the surface of the fan during long-term permafrost and progressive decrease of humidity of the climate at the turn of the Pleni- to the Late Weichselian; 3) the upper unit accumulated following the development of longitudinal dunes at the turn of the Late Weichselian to the Holocene; the development of dunes was interrupted twice by the form being stabilised by vegetation and soil development.

In this paper, we report the results of the research on the fluvio-aeolian deposit succession in the Jozefow site in the region of Roztocze Tomaszowskie (SE Poland). Based on the lithofacial and textural analyses, as well as TL and IR-OLS dating, three lithofacial units have been documented, including their age. They are as follows: 1) a fluvial (lower) unit deposited in the Pleniglacial in the channel of a sandbed braided river under permafrost conditions; 2) a fluvio-aeolian (middle) unit which originated due to alternating aeolian and fluvial deposition and redeposition within a floodplain and/or a zone of abandoned channels at the end of the Pleniglacial and the beginning of the Late Glacial when permafrost was gradually degrading and the climate humidity was decreasing. The top part of the fluvio-aeolian deposits has been reworked by pedogenic processes leading to the development of a soil, which indicates a break in the sediment deposition; 3) an aeolian (upper) unit accumulated due to the development of the sandy aeolian forms (moving dunes) at the end of the Late Glacial and the beginning of the Holocene.

Micromorphology of quartz sand grains is used to reconstruct processes occurring in the glacial environment and to distinguish the latter from other environments. Two processes dominate in the glacial environment, i.e., crushing and abrasion, or a combination thereof. Their effect is a wide range of microstructures on the surface of quartz grains, e.g., chattermarks, conchoidal fractures and multiple grooves. However, the periglacial environment also effectively modifies the surface of quartz grains. The active layer of permafrost is considered to have a significantly higher contribution to the formation of crushed grains and the number of microstructures resulting from mechanical destruction (e.g., breakage blocks or conchoidal fractures), as compared to deposits which are not affected by freeze–thaw cycles. However, only a few microstructures are found in both environments. At the same time, there are several processes in subglacial environments related to freeze–thaw cycles, e.g., regelation, congelation, basal adfreezing, and glaciohydraulic supercooling. Most likely, therefore, the role of the glacial environment in the destruction of quartz grains has been misinterpreted, and consequently the conclusions regarding environmental processes drawn on the basis of the number of crushed grains and edge-to-edge contacts are erroneous.

Geological investigations in the southern part of the Polish-Belarusian cross-border area were focused on correlation of main Middle Pleistocene stratigraphic units and on extent of the ice sheet of the Saalian Glaciation. Determination of regional stratotype horizons, establishing new key sites and sections of regional significance for Central Europe were based mostly on vegetation and paleoclimate changes recorded in glacial and interglacial lake deposits. Results of stratigraphical investigations abolished a predominant palaeogeographic image on ice sheet limits in this area. The Saalian maximum ice sheet limit was similar or even less extensive than during the subordinate Warta Stadial. Most of the area between the Middle Vistula in Poland and the Middle Dnieper in Belarus and the Ukraine was ice-free during this glaciation. On the other hand, immense glacial lobes during Saalian in the Middle Vistula and the Middle Dnieper valleys have not advanced presumably in the same time and were fed by ice moving from different parts of Scandinavia. Diversified Pleistocene tectonic uplifting in the area influenced much dynamics of the penultimate ice sheet in this part of Europe.

The paper presents a research on a marginal zone near Knyszewicze in the southern part of Sokółka Hills (northeastern Poland). Terminal moraine hills are arranged amphitheatrically in a lobal pattern. Dynamics of the Knyszewicze frontal ice-sheet lobe during the Saale Glaciation and successive stages of the marginal zone near the village of Knyszewicze were reconstructed based on sedimentary and geomorphological analysis, using a digital elevation model and morpholineaments. Three main phases of the Knyszewicze glacial-lobe activity were identified including accumulation of glaciofluvial deposits, advances of the ice margin and ice-lobe retreat. Moraine hills developed at a stable ice-lobe terminus, initially as short end-moraine fans with the following sequence of lithofacies Gh⇒SGh⇒Sh or Gm⇒Gh⇒Sh. Such a sequence indicates cyclic sheet-floods. During a small but dynamic advance of the ice sheet terminus, these deposits were moved forward and monoclinally folded, then furrowed with sloping faults due to horizontal pressure. Typical thrust-block push moraines developed in this way. Ice sheet advance took place when permafrost was present in the substratum and very high water pressure occurred at glacial terminus. Inside a lobal configuration of moraines, there is a rich inventory of glacial forms with a classic terminal depression in the central part. Based on this landform pattern, their shape, rhythm and glaciotectonic disturbances, the land relief may be referred to as a hill-hole pair. The structure of Horczaki Knoll, deposited on the sub-Quaternary tectonic structure, significantly contributed to a development of this marginal zone.