Dead Ice Research Articles

The terrestrial Eemian to late Weichselian sediment record at Beckentin (NE-Germany): First results from lithostratigraphic, palynological and geochronological analyses

Over recent decades a growing number of well-documented records from terrestrial last interglacial sites across central Europe have substantially improved our understanding of Eemian climate and landscape dynamics. Despite this progress, there are also large areas from which little information is available, thus constituting significant paleo-geographic gaps in the last interglacial record. Among the regions with still inadequate paleo-environmental information is the maritime-influenced area of NE-Germany at the southern margin of the Eemian (Baltic) Sea. Here we present first results from a geological investigation of a new last interglacial site, recently discovered during archaeological excavations near Beckentin (SW-Mecklenburg). The study area is located approximately 25 km to the south of the maximum MIS-2 ice limit of the Scandinavian Ice Sheet in NE-Germany, and thus lies outside the Weichselian belt of glaciation. Based on lithostratigraphic and sedimentological logging, complemented by geochemical (XRF) and palynological investigations, we divide the local succession into three sections: (1) a basal facies comprising Saalian till and associated glaciofluvial sand, overlain by section (2) consisting of a fen peat which grades into laminated organic to minerogenic mud. The organic deposits of section (2) preserve a near complete Eemian pollen inventory, encompassing pollen zones (PZ) I to VI (Menke and Tynni 1984). Above this rest poorly sorted periglacial sands (section 3) with ventifacts and evidence for cryogenic deformation. Geochronological results from 230Th/U dating of the buried organic-rich deposits at Beckentin, show that these units accumulated in a former dead ice depression between 118 ± 7/6 ka and 114 ± 6/5 ka during the Eemian Interglacial. High-resolution optically stimulated luminescence (OSL) profiling, undertaken with a portable luminescence reader, reveals a significant hiatus between the lacustrine fines and overlying periglacial cover sand. Five OSL ages obtained from these cover sediments and the sand-filling of an ice-wedge cast show that these strata formed between during the last glacial - interglacial transition.

UAS-Based Change Detection of the Glacial and Proglacial Transition Zone at Pasterze Glacier, Austria

Glacier-related applications of unmanned aircraft systems (UAS) in high mountain regions with steep topography are relatively rare. This study makes a contribution to the lack of UAS applications in studying alpine glaciers in the European Alps. We transferred an established workflow of UAS-based change detection procedures to Austria’s largest glacier, the Pasterze Glacier. We focused on a selected part of the glacier tongue and its proglacial vicinity to obtain detailed knowledge of (i) the behavior of a lateral crevasse field, (ii) the evolution of glacier surface structures and velocity fields, (iii) glacier ablation behavior and the current glacier margin, and (iv) proglacial dead ice conditions and dead ice ablation. Based on two UAS flight campaigns, accomplished in 2016 (51 days apart), we produced digital elevation models (DEMs) and orthophotos with a ground sampling distance (GSD) of 0.15 m using Structure-from-Motion (SfM) photogrammetry. Electrical resistivity tomography (ERT) profiling was additionally conducted in the proglacial area. Results indicate distinct changes in the crevasse field with massive ice collapses, rapid glacier recession, surface lowering (mean of −0.9 m), and ice disintegration at the margins, calculated degree day factors on the order of −7 to −11 mm d−1·°C−1 for clean ice parts, and minimal changes of the debris-covered dead ice in the proglacial area. With this contribution we highlight the benefit of UAS in comparison to commonly used terrestrial methods and satellite-related approaches.

Glaciation of Siberia and the problem of massive ice beddings

As a result of many years of the author’s studies of glaciers and ground ices, a great amount of factual material has been collected for a purpose to analyze a possibility of burying the glaciers in the permafrost zone and to esti‑ mate a time of their stay in such а condition. According to the author’s opinion, the Siberian glaciers were mainly the valley ones; ice sheets were never formed, and any existence of buried glaciers could not be real in the geo‑ logical time scale. However, some researchers still believe that in the Quaternary ice sheets occurred in the North of Siberia, and, in addition, they consider the local massive ice beddings as relics of these sheets. No clear expla‑ nation of the similar origin of such ice structures exists at the present time, so development and variety of this ice could be easier explained by the permafrost genesis. Basing on results of observations carried out in all glacier regions of Siberia, the author concludes that glaciers cannot exist in the form of buried ice for a long time. This is unrealistic even in the North‑East of Siberia, where the absolute minimum temperature is −67.8 °C, and the mean annual air temperature drops below −17 °C. The characteristic feature of the Siberia continental climate is short, but hot summer. In such a situation, the coarse fragmental morainic material, covering glaciers by the layer up to 3 m thick, cannot preserve the underlying ice from melting because the heat penetrates down with the air, liquid precipitation, and the melt water. When glaciers reduce, the dead ice, buried under a moraine, may be preserved in the coldest areas of Siberia for only 100–150 years. Therefore, despite the resemblance of the scarps of the ice bodies having the permafrost or glacial origin, consideration of them as relics of ancient glaciers would be wrong.

Frontal recession of Parkachik Glacier between 1971-2015, Zanskar Himalaya using remote sensing and field data

Parkachik Glacier is located in the Suru sub-basin of the Upper Indus River, Zanskar Himalaya. The Glacier has been analysed using Corona KH-4B (1971), Landsat-TM (1999), field survey (2015), Google EarthTM (2015) and ASTER GDEM (2015) for frontal recession and area changes. Overall, from 1971 to 2015, the Glacier has retreated by 127 ± 0.09 m i.e. (0.75 ± 0.07%) at a rate of 2.9 ± 0.004 ma−1 with a simultaneous decrease in area from 49.5 to 48.8 km2 i.e. 740 ± 0.7 m2 (1.5 ± 0.09%) at a rate of 74 ± 0.7 m2a−1. However, during recent decade (1999–2015), the rate of glacier recession of 3.9 ± 0.004 ma−1 with a corresponding area loss of 500 ± 0.74m2 (1 ± 0.1%) was higher than the retreat rate of 2.3 ± 0.001 ma−1 and an area loss of 240 ± 0.02m2 (0.48 ± 0.08%) during 1971–1999. In the field, the evidences of glacier recession are present in the form of separated dead ice blocks from the main Glacier, recessional dumps/moraines, active ice calving activity and a small proglacial pond/lake at the terminus/snout of the Glacier. However, the recession over the studied period has been very slow and is controlled by its topographic configuration, particularly the large altitudinal range (6030–3620 m), almost northerly aspect and steep slope (average ~ 30°).

A lake-bog succession vs. climate changes from 13,300 to 5900 cal. BP in NE Poland in the light of palaeobotanical and geochemical proxies

This paper presents and discusses the influence of climatic and edaphic factors on vegetation succession of the postglacial Lake Czarne (LC) located in NE Poland. On the basis of pollen, macroscopic plant remains, non-pollen palynomorphs (NPPs), and geochemical analyses, we reconstructed the transition from a clear oligotrophic lake to an ombrotrophic mire from 13,300 to 5900cal. BP. Climatic events/periods that may have affected the lake/mire succession were as follows: (i) relatively warm conditions in the younger part of the Younger Dryas (ca. 12,220cal. BP) that led to water eutrophication recorded as blooms of Scenedesmus ellipticus, whose response preceded that of woodland vegetation by ca. 200years, (ii) the warming of the Late Glacial–Holocene transition and early Holocene that caused the final melting of dead ice block(s) and led to the deepening of the water body and/or an increase in the water level, the retreat of submerged macrophytes, and the enrichment of waters with sulphur, (iii) the global cold period between 8600 and 8000cal. BP that contributed to a rise in the water level during the phase of sedge swamp and enabled the reappearance of Nymphaeaceae and blooms of S. ellipticus (ca. 8570–8500cal. BP), and (iv) the global climate cooling 6500–5900cal. BP that still remains enigmatic in terms of palaeobotanical patterns; however, geochemical markers point to an increase in the water level and enhanced erosion in the LC catchment ca. 6200–6000cal. BP. Lake terrestrialization resulted in the concurrent appearance of microhabitats suitable for mosses with contrasting ecological preferences, e.g., Warnstorfia exannulata (acidic) and Scorpidium revolvens (alkaline), or Straminergon stramineum (acidic), Meesia triquetra (alkaline) and S. revolvens (alkaline).

Towards a morphogenetic classification of eskers: Implications for modelling ice sheet hydrology

Validations of paleo-ice sheet hydrological models have used esker spacing as a proxy for ice tunnel density. Changes in crest type (cross-sectional shape) along esker ridges have typically been attributed to the effect of changing subglacial topography on hydro- and ice-dynamics and hence subglacial ice-tunnel shape. These claims assume that all eskers formed in subglacial ice tunnels and that all major subglacial ice tunnels produced a remnant esker. We identify differences in geomorphic context, sinuosity, cross-sectional shape, and sedimentary architecture by analysing eskers formed at or near the margins of the last Cordilleran Ice Sheet on British Columbia's southern Fraser Plateau, and propose a morphogenetic esker classification. Three morphogenetic types and 2 subtypes of eskers are classified based on differences in geomorphic context, ridge length, sinuosity, cross-sectional shape and sedimentary architecture using geophysical techniques and sedimentary exposures; they largely record seasonal meltwater flows and glacial lake outburst floods (GLOFs) through sub-, en- and supraglacial meltwater channels and ice-walled canyons.General principles extracted from these interpretations are: 1) esker ridge crest type and sinuosity strongly reflect meltwater channel type. Eskers formed in subglacial conduits are likely to be round-crested with low sinuosity (except where controlled by ice structure or modified by surging) and contain faults associated with flank collapse. Eskers formed near or at the ice surface are more likely to be sharp-crested, highly sinuous, and contain numerous faults both under ridge crest-lines and in areas of flank collapse. 2) Esker ridges containing numerous flat-crested reaches formed directly on the land-surface in ice-walled canyons (unroofed ice tunnels) or in ice tunnels at atmospheric pressure, and therefore likely record thin or dead ice. 3) Eskers containing macroforms exhibiting headward and downflow growth likely record flood-scale flows (possibly GLOFs where a lake can be inferred). These conclusions suggest that esker crest type, sinuosity and geomorphic context, when understood along with sedimentary architecture, largely reflect formational position with respect to the ice-surface. Reconstructions of ice sheet hydrology need to account for variation in esker morphology because basing hydrodynamic inferences on the presence or absence of an esker alone ignores encoded differences in water source, supply, flow magnitude and frequency, and conduit position.

Lateglacial and Holocene environmental history in the area of Samogitian Upland (NW Lithuania)

Pollen, plant macrofossil and carbonate analyses supplemented with 14C dating were applied for Lopaičiai hollow and Pakastuva Lake sediment sequences. The new data obtained from two sediment cores were used to reconstruct vegetation cover and environmental changes during Lateglacial and Holocene in Samogitian Upland (NW Lithuania). Different burial conditions of dead ice blocks caused different time of lake sediment start in studied sites. The depositional and vegetation cover history is traced starting at pre-Allerød time in sediment sequence from Lopaičiai core. However, sediment sequence from Pakastuva core provides paleoenvironmental information starting only from the very beginning of Holocene. The study results bring more light on environmental development during Lateglacial and Holocene of specific ice marginal area, which is interlobate insular upland.

ON THE RESTRUCTURING OF DRAINAGE NETWORK OF THE BASE OF MOUNT ELBRUS

From 1957 to 2010, glaciers at the northeast foothills of Elbrus have significantly decreased in size. The area of the glaciers Birdzhalychiran and Chungurchatchiran have shrunk by 5.7 square kilometers. The shrinking in glacier thickness and the reduction in flow of glacier waters have resulted in the formation of barriers that look like riegels; at the same time, barriers that formed by dead ice of the medial moraine disappeared. This situation induced the constant change of glacial flow direction and the breach of lakes. The prediction for this area gives forthcoming radical reforming of the water network because of disappearance of the medial moraine ridge and the joining of the right-hand side of the river Birdzhaly-Su to the merging point of the river Kara-Kaya-Su.

Integrated hazard assessment of Cirenmaco glacial lake in Zhangzangbo valley, Central Himalayas

Glacial lake outburst floods (GLOFs) have recently become one of the primary natural hazards in the Himalayas. There is therefore an urgent need to assess GLOF hazards in the region. Cirenmaco, a moraine-dammed lake located in the upstream portion of Zhangzangbo valley, Central Himalayas, has received public attention after its damaging 1981 outburst flood. Here, by combining remote sensing methods, bathymetric survey and 2D hydraulic modeling, we assessed the hazard posed by Cirenmaco in its current status. Inter-annual variation of Cirenmaco lake area indicates a rapid lake expansion from 0.10±0.08km2 in 1988 to 0.39±0.04km2 in 2013. Bathymetric survey shows the maximum water depth of the lake in 2012 was 115±2m and the lake volume was calculated to be 1.8×107m3. Field geomorphic analysis shows that Cirenmaco glacial lake is prone to GLOFs as mass movements and ice and snow avalanches can impact the lake and the melting of the dead ice in the moraine can lower the dam level. HEC-RAS 2D model was then used to simulate moraine dam failure of the Cirenmaco and assess GLOF impacts downstream. Reconstruction of Cirenmaco 1981 GLOF shows that HEC-RAS can produce reasonable flood extent and water depth, thus demonstrate its ability to effectively model complex GLOFs. GLOF modeling results presented can be used as a basis for the implementation of disaster prevention and mitigation measures. As a case study, this work shows how we can integrate different methods to GLOF hazard assessment.

Natural transformation of the Romoty paleolake (NE Poland) during the Late Glacial and Holocene based on isotopic, pollen, cladoceran and geochemical data

“Romoty” is the name of a sediment profile from the overgrown lake located in Ełk Lakeland (NE Poland). The sediment core, which is 8.4 m in length, documents the development of the reservoir since the melting of dead ice and formation of the lake basin, i.e., before 13,000 years BP, until it became overgrown with plants. The characteristics of the sediments changed from mineral deposits on the bottom (silty sands) to biogenic deposits consisting of dark olive calcareous detritus gyttja and light calcareous gyttja with increasing carbonate content and to peat in the upper part.Based on the data (chemical, stable isotopes, subfossil Cladocera remains, pollen), we have distinguished three main stages of the evolution of Romoty paleolake. The first stage includes the formation of the lake basin in the Late Glacial and early Holocene (Preboreal). The second stage is characterized by the harmonic, natural development of the Romoty paleolake from the Boreal to Subboreal. This stage coincides with a period of climatic warming, and biogenic sediments accumulated in this reservoir at that time. The third stage concerns the disappearance of the lake in the late Holocene (Subatlantic). The lake conditions declined, and the reservoir completely filled with sediments and has transformed into a mire. The characterization of each stage involves a description of environmental conditions occurring in the Romoty paleolake, particularly the Cladocera community, the chemical composition, the temperature and trophy of the water, the water level, the nature of bottom sediments, and the plants occurring in the reservoir and its surroundings.The lowest water temperature occurred in the Late Glacial and Preboreal periods. Since the Boreal period, gradual warming is observed and is expressed through a positive trend in both δ18O and δ13C and changes in both Cladocera and plant compositions. The lake was deepest at the beginning of the Holocene as a result of dead ice melting (supply of melt water; lowering of the lake bottom) and/or increased precipitation (change in atmospheric circulation). The water level fell during the Atlantic period. Additionally, the cladoceran and non-pollen palynomorph data indicate low trophy followed by an increase in the mesotrophic state. Human impact was documented only by a low occurrence of pollen grains of Cerealia in the youngest sediments (Subatlantic period), suggesting a low penetration by human groups of the area near the Romoty paleolake.

FORMATION OF CERTAIN CRATER-LIKE LAKE BASINS: RESULTS FROM THE LAKE SVETLOE (MOSCOW REGION)

The basin of the lake Svetloe was created before the Moscow Ice Age by karst process in carboniferous rocks. Deposits of the rim surrounding the lake are similar to those of kames, which arise from accumulation of aqueglacial deposits in the cavity under the dead ice, and after the collapse of the cavity roof in the englacial lake. The part of aqueglacial deposits was accumulated in the basin of the lake, while other part formed the annular rim on its shores. After the melting of the glacier, ice shores of the lake and part of its water content disappeared. The lake deposits remain as a rim elevated above surrounded plain. Some other crater-like basins in the Moscow region could be created by periglacial processes during late Moscow or late Valdai ice ages at the places of the collapsed pingos.

Evolution and outburst risk analysis of moraine-dammed lakes in the central Chinese Himalaya

The recent evolution and outburst risk of two typical moraine-dammed lakes, Galong and Gangxi, central Chinese Himalaya, are analyzed using topographic maps from 1974 and Landsat satellite imagery acquired in 1988, 2000 and 2014. The datasets show the areas of Galong and Gangxi lakes increasing at rates of 0.45 and 0.34 km2/year during the period 1974–2014, an expansion of 501% and 107%, respectively, in the past 41 years, while the areas of the parent glaciers, Reqiang and Jipucong decreased by 44.22% and 37.76%, respectively. The accelerating retreat of the glaciers not only reflects their generally negative mass balance but is consistent with the rapid expansion of the moraine-dammed lakes. When acted upon by external forces such as earthquakes, heavy rainfall, rapid melting of glaciers and dead ice, and snow/ice/rock avalanches, these lakes can become extremely dangerous, easily forming outburst mudslides, which can potentially spread to the Poiqu river basin and develop into cross-border (China and Nepal) GLOF disasters. Therefore, there is an urgent need to strengthen integrated risk management of glacial lake outburst disasters with multiple objectives and modes.

Climatic and morphological controls on diachronous postglacial lake and river valley evolution in the area of Last Glaciation, northern Poland

The Wda River valley in northern Poland is a polygenetic valley located in a former subglacial meltwater channel that after ice sheet retreat hosted separate and then interconnected lake basins, subsequently replaced by a river. In one part of the river system an abandoned Lateglacial valley is found. This dry valley is a unique feature in the area located within the limit of the Scandinavian Ice Sheet during the Last Glaciation in the Central European Lowland. We investigated lacustrine and fluvial sediments and landforms in the valley and applied palynological analysis combined with radiocarbon dating to reconstruct the valley evolution from the early period of river inception in the Lateglacial through the formation of lakes during the Pleistocene/Holocene transition up to the establishment of a modern river system in the early Holocene. Three coeval processes were identified: (1) formation of lake basins in the subglacial channel connected by a river, (2) erosion of the river bed between the lakes, and (3) sediment deposition at the mouths of the channels in the lake basins first generating delta fans and eventually filling the lakes entirely. The valley formation was associated with diachronous melting of dead ice blocks buried in the subglacial channel controlled by the capacity of the hydrological system to evacuate the meltwater. Most of the lake basins in the study area were formed during the Bølling–Allerød period, but one section of the subglacial channel not affected by thermokarst processes survived protected by dead ice blocks throughout the entire Lateglacial. Accelerated dead-ice decay at the beginning of the Holocene triggered widespread lowering of the base level, which caused lake disappearance and the formation of the modern river system. The processes reconstructed in the central section of the Wda River indicate a highly dynamic and diachronous river valley development during the Lateglacial and early Holocene whereby the valley formation was interwoven with the formation of lake basins within the valley triggered by melting of dead ice blocks in the substratum.

Recent transformations in the high‐arctic glacier landsystem, ragnarbreen, svalbard

agnarbreen is a small glacier located in the central part of pitsbergen sland (valbard archipelago) and fed by the larger ice mass of ittag‐efflerbreen. Glacier recession and landforms' development in the foreland of agnarbreen are quantified using time‐series orthophotos and digital elevation models, which were generated based on aerial photographs from 1961 (black and white frame camera), 1990 (false infrared frame camera) and 2009 (colour digital camera), obtained from the orsk olar nstitute.Receding from its maximum ittle ce ge extent, attained in the period 1900/1920–2013, the glacier margin retreated by 1658 m while the extent of the area of ice decreased by 26%. The glacier snout lost 135 million m3 of ice during the period 1961–2009, whereas landform changes (mainly due to dead‐ice melting and debris flow activity) were more than twenty‐five times lower, with the less than 5 million m3 of sediment and dead ice volume loss. In terms of landscape alteration between 1961 and 2009, the most important was the creation of a terminoglacial lake, which acted as a sedimentary trap and at the same time probably accelerated glacier retreat. The second most active component was the lateral moraines whose transformations were divided into four phases, with various magnitudes of debris flow and backwasting activity that changed with time. The end moraine complex was the most stable component, affected mainly by dead‐ice downwasting and to a lesser extent by sporadic debris flows.

The role of melting dead ice on landscape transformation in the early Holocene in Tuchola Pinewoods, North Poland

On the basis of macrofossil and pollen analyses, AMS 14C-dating, and geomorphological investigations, we reconstructed the development of hydrological changes during the Lateglacial to early Holocene transition in Tuchola Pinewoods (Bory Tucholskie) in northern Poland. In this region, the Wda River flows in polygenetic valleys, typical for the young glacial landscape of the northern central European lowlands. The middle section of this river provides a suitable setting to demonstrate the environmental and hydrological changes in the Late Glacial and early Holocene, because (1) it is a small and well-defined area and (2) the existence of a morphologically preserved river valley from late glacial period. In this study, we focused on a short terrestrial sediment core (48 cm) that represents four phases of landscape evolution during the early Holocene: telmatic, lacustrine, lacustrine-fluvial and alluvial. Abrupt changes in lithology and sediment structures exhibit rapid changes and threshold processes in environmental conditions. The AMS 14C dating of terrestrial plant remains revealed an age for the basal sediments of 11 223 ± 23 cal BP and thus falls within the Preboreal biozone. Plant macrofossil indicators provide evidence of water level and edaphic changes in the basin. The results of our study demonstrate a strong influence of melting buried ice blocks on the geomorphological development, hydrological changes in the catchment, and the biotic environment in the early Holocene.

Regional and local changes inferred from lacustrine organic matter deposited between the Late Glacial and mid-Holocene in the Skaliska Basin (north-eastern Poland)

The article presents the results of a combination of isotopic (δ15N and δ13C), geochemical (TOC, TN, C/N) and palaeobotanical investigations. They were carried out on organic matter (OM) that had been deposited from the Younger Dryas to the Subboreal chronozone in palaolake sediments (north-eastern Poland). OM from the late Younger Dryas consists only a small amount of TOC and TN, which together with the lack of aquatic macrophyte macrofossils confirm low primary production in the then reservoir. The higher values of C/N ratio (18–27) and δ13C (ca. −26‰) suggest that OM was mainly terrestrial in origin. During the Preboreal chronozone (11,450–10,150 cal. BP), there was a probable deepening of the reservoir through the melting of dead ice. This might have been intensified by an increase in precipitation and a fall in evapotranspiration during the ‘Preboreal oscillation’. From the early Preboreal chronozone (ca. 11,345 cal. BP), a mixed source of OM is indicated by C/N ratio (from 8 to 13). At the same time significant increase in TOC and TN probably registered a rise in primary production in the palaeolake. From the older part of the Boreal chronozone (ca. 9865 cal. BP) algae productivity increased (the C/N ratio dropped to ca. 8 and was then constant). At the beginning of the Atlantic chronozone (ca. 8650 cal. BP) a probable increase in the water level caused the partial relocation of OM from the reed swamp belt and/or the adjacent alder carr into deeper sections of the palaeolake (an increase in TOC and TN). In the late Atlantic chronozone (ca. 6965–6650 cal. BP), TOC and TN decreased while δ13C had high values, which probably reflected a more distinct stratification of the water column with anoxic bottom waters. Next, in the late Atlantic and early Subboreal chronozone (ca. 6650–5205 cal. BP) the amount of OM in palaeolake sediments was still rising. The δ13C values dropped, suggesting an intensification of processes of water mixing. These processes were simultaneous with the constant shallowing of the palaeolake and the disappearance of habitats suitable for submerged macrophytes. The topmost part of the profile is characteristic of a strong decomposition of peat, causing a release of carbon dioxide and therefore the depletion of the carbon pool in the peat (a drop in the C/N ratio). The concurrent upward trend of the δ15N curve is probably the effect of a greater anthropogenic impact on the palaeolake/mire and its catchment and/or more recent human interference in the topmost peat layers.

Mosses and the beginning of plant succession on the Walker Glacier, southeastern Alaska

Three mosses, a basidiomycete fungus (perhaps Mycena) and seedlings (perhaps Epilobium) are reported as growing on dead ice of a glacier in southeastern Alaska. By far the most abundant species was Racomitrium fasciculare which appears to begin directly on the ice, and trapping mineral particles, grows up mostly into irregularly shaped patches but it can become more or less hemispheroidal on pedestals of ice. Many of the tufts of which there are thousands, develop to face southeast on tiny mounds of ice and protect the ice to the northwest. However, none appear to become ‘glacier mice’ (more or less spheroidal and lying loose on the ice surface). Sanionia uncinata invades the Racomitrium, as does Pohlia filum. The fungus and three seedlings also occurred only on the moss tufts. In its precise features and topographic situation, this beginning of plant succession on dead ice is of a classical Clementsian type and contrasts strongly with many of the other occurrences of mosses on glaciers in North America, Iceland and Svalbard.

Impact of the German Harz Mountain Weichselian ice-shield and valley glacier development onto Palaeolithic and megafauna disappearances

Three Pleistocene stages are recorded by 3D Google-Earth geomorphology, cave sediments, river terraces, megafauna, archaeological sites of the Harz Mountain Range and its forelands of northern Germany (central Europe, peak 1141 a.s.l.). Late Pleistocene glaciation stages are modeled preliminary in valley elevations between 407 and 760 a.s.l., starting all southeast below the Brocken Ice Field (above 750 a.s.l.). The 14–11 km long Oder and Bode Valley glaciers left typical moraines, kames, or dead ice depressions, such as fluvial cave relic sediments. The Bode River glacier passed during the LGM the Rübeland Caves, where it deposited reworked kames/lateral moraines in the Baumann's Cave, which floods mixed a Neanderthal camp, leopard lair and cave bear den area. 60 km downstream, fluvial to aeolian deposits were trapped in the gypsum karst doline Westeregeln (Neanderthal camp/hyena den). Late Aurignacians replaced in the region Neanderthals, but a gap of Late Palaeolithic (Gravettian–Magdalenian – 26,000–16,000 BP) settlement, and latest starting speleothem genesis (around 24,260 ± 568 BP) correlate to the LGM, when an “arctic reindeer fauna” with alpine elements (ibex, chamois) accumulated in bone assemblages of a wolverine, polar fox, mustelid, such as European eagle owl dens, which allow landscape reconstructions.

Late Glacial–early Holocene environmental changes in Charzykowskie Lake (northern Poland) based on oxygen and carbon isotopes and Cladocera data

Based on isotopic and cladoceran investigations of a 6-m-long sediment core, a reconstruction of paleoenvironmental dynamics in Charzykowskie Lake (northern Poland) is proposed. The sediments consist of sandy silts at the bottom, followed (in upward succession) by gyttja characterized by increasing CaCO3 content. The measured δ18O values oscillate from −9.3 to −5‰ and δ13C from – 5.7 to +0.4‰. We identify 24 taxa of subfossil Cladocera and six phases (CAZ) of faunal development. Isotopic and cladoceran data together with detrended correspondence analyses (DCA) allow reconstruction of the environmental conditions, particularly changes in water level, temperature, and trophic status, during the Late Glacial and early Holocene. The lowest water temperature, connected with the inflow of cold melt water, occurred in the Late Glacial and Preboreal period. Since the Boreal period, gradual warming is observed and expressed through a positive trend in both δ18O and δ13C values and changes in Cladocera species assemblages. The lake was deepest at the beginning of the Holocene as a result of dead ice melting (supply of melt water; lowering of lake bottom) and/or precipitation increase (change in atmospheric circulation). During the Boreal period, the fall in water level takes place despite the opposite trend observed at nearby sites. In addition, the cladoceran data indicate an initial decrease in trophic conditions from α-mesotrophic to oligotrophic and then an increase to the β-mesotrophic state.

The development and genesis of a small thaw lake filling the Skaliska Basin during the Late Glacial and Holocene

ABSTRACT The northern part of the Mazury Lake District is marked by the presence of a depression described as the Skaliska Basin. At the end of the Pleistocene, the Skaliska Basin was the site of functioning of a thaw lake, within series of laminated clayey sediments were formed. The surface of the clayey sediments was overlain by a sandy fan. Blocks of dead ice underlying the fan and the overlying surface of the clayey sediments were the origin of small isolated water basins. Since the Allerod they were filled with limnic sediments, passing into peats towards the upper part. In order to reconstruct the vegetational history of the Skaliska Basin and the conditions of sedimentation of the lacustrine gyttjas and peats, several sections were obtained from such basins and subjected to examination of plant macroremains, palaeolimnological analysis and AMS dating. Sedimentation of lacustrine sediments began with sands with an admixture of silt and peat. The beginning of sedimentation of lacustrine sands of aeolian origin falls within the Allerod, whereas the end of that process in ca the middle of the Preboreal. Sands are frequently overlain by a strongly decomposed lacustrine dy sediment. Subsequently a sequence of detritus gyttja accumulated. The complex of gyttjas is interbedded with occasional Scirpo-Typheti peats. Sedimentation of lacustrine sediments is followed by accumulation of peats formed within communities with tall sedges. These communities, according to their compoition, correspond to the associations of Cicuto- Caricetum pseudocyperi Boer. et Siss. and Caricetum elatae Koch. The upper part comprises peats resembling the present-day community of Sphagnum centrale, displaying features of a transition bog. Also the occurrence of Eriophorum vaginatum confirms changes towards ombrotrophic conditions. The uppermost part of the sections often comprises heavily decomposed peat with components no longer identifiable by macroscopic analysis.