Late Glacial Early Holocene Research Articles

First automatic size measurements for the separation of dwarf birch and tree birch pollen in MIS 6 to MIS 1 records from Northern Germany.

During past glacial periods, the land cover of Northern Eurasia and North America repeatedly shifted between open steppe tundra and boreal/temperate forest. Tracking these changes and estimating the coverage of open versus forested vegetation in past glacial and interglacial landscapes is notoriously difficult because the characteristic dwarf birches of the tundra and the tree birches of the boreal and temperate forests produce similar pollen grains that are difficult to distinguish in the pollen record. One objective approach to separating dwarf birch pollen from tree birch pollen is to use grain size statistics. However, the required grain size measurements are time-consuming and, therefore, rarely produced. Here, we present an approach to automatic size measurement based on image recognition with convolutional neural networks and machine learning. It includes three main steps. First, the TOFSI algorithm is applied to detect and classify pollen, including birch pollen, in lake sediment samples. Second, a Resnet-18 neural network is applied to select the birch pollen suitable for measurement. Third, semantic segmentation is applied to detect the outline and the area and mean width of each detected birch pollen grain. Test applications with two pollen records from Northern Germany, one covering the Lateglacial-Early Holocene transition and the other covering the Mid to Late Pleistocene transition, show that the new technical approach is well suited to measure the area and mean width of birch pollen rapidly (>1000 per hour) and with high accuracy. Our new network-based tool facilitates more regular size measurements of birch pollen. Expanded analysis of modern birch pollen will help to better understand size variations in birch pollen between birch species and in response to environmental factors as well as differential sample preparation. Analysis of fossil samples will allow better quantification of dwarf birch versus tree birch in past environments.

Persistence of Holocene ice cap in northeast Svalbard aided by glacio-isostatic rebound

The deglaciation of the Svalbard-Barents Sea Ice Sheet was driven by relative sea-level rise, the incursion of North Atlantic waters around Spitsbergen, and increasing summer insolation. However, ice retreat was interrupted by asynchronous re-advances that occurred into high relative seas, during a period associated with warm regional waters and elevated summer temperatures. Better understanding of this complex style of deglaciation and the dynamic response to a warming climate can serve as an important analogue for modern warming and today's ice sheets. We present evidence from northern Svalbard of glacier re-advances during the Late Glacial-Early Holocene in hand with relative sea-level history and the occurrence of thermophilous molluscs. We argue that glacio-isostatic adjustment during the transition into the Holocene influenced ice marginal dynamics and as a result, the southern region of the Åsgardfonna ice cap persisted through the Holocene Thermal Maximum.

Diverse phenotypes of Late Glacial–Early Holocene downy birch (Betula pubescens Erh.) and the morphology of early Preboreal tree stands in southern Schleswig-Holstein

Abstract. The flexibility in growth of Betula pubescens is taken as example for possible erroneous imaginations of Late Glacial–Early Holocene living conditions. The article highlights the factors influencing the phenotype of the contemporary plants, as well as the small-scale patchiness of the distribution of the vegetation in the landscape. The area of investigation is the southern Weichselian younger morainic area of Schleswig-Holstein, including a major Late Glacial archaeological type locality – the Ahrensburg tunnel valley. The period under investigation spans the time between 11 700 and 11 400 cal BP and hence the Late Glacial–Early Holocene transition, which is characterized by a significant shift in the vegetation. This shift has often been seen as a simple transition from treeless tundra to birch forest. The aim of the article is to provide a more realistic image of plant cover of the late Dryas 3 period and the Early Holocene period before the Preboreal oscillation by considering past natural growth limits of Betula pubescens in the study area. The intention is to provide a more accessible interpretation of palaeobotanical data to non-specialists, especially in archaeology.

A Continuous Centennial Late Glacial-Early Holocene (15-10 cal kyr BP) Palynological Record from the Iberian Pyrenees and Regional Comparisons.

This paper presents the first continuous (gap-free) Late Glacial-Early Holocene (LGEH) pollen record for the Iberian Pyrenees resolved at centennial resolution. The main aims are (i) to provide a standard chronostratigraphic correlation framework, (ii) to unravel the relationships between vegetation shifts, climatic changes and fire, and (iii) to obtain a regional picture of LGEH vegetation for the Pyrenees and the surrounding lowlands. Seven pollen assemblage zones were obtained and correlated with the stadial/interstadial phases of the Greenland ice cores that serve as a global reference. Several well-dated datums were also derived for keystone individual taxa that are useful for correlation purposes. Four vegetation types were identified, two of them corresponding to conifer and deciduous forests (Cf, Df) and two representing open vegetation types (O1, O2) with no modern analogs, dominated by Artemisia-Poaceae and Saxifraga-Cichorioideae, respectively. Forests dominated during interstadial phases (Bølling/Allerød and Early Holocene), whereas O1 dominated during stadials (Oldest Dryas and Younger Dryas), with O2 being important only in the first half of the Younger Dryas. The use of pollen-independent proxies for temperature and moisture allowed the reconstruction of paleoclimatic trends and the responses of the four vegetation types defined. The most relevant observation in this sense was the finding of wet climates during the Younger Dryas, which challenges the traditional view of arid conditions for this phase on the basis of former pollen records. Fire incidence was low until the Early Holocene, when regional fires were exacerbated, probably due to the combination of higher temperatures and forest biomass accumulation. These results are compared with the pollen records available for the whole Pyrenean range and the surrounding lowlands within the framework of elevational, climatic and biogeographical gradients. Some potential future developments are suggested on the basis of the obtained results, with an emphasis on the reconsideration of the LGEH spatiotemporal moisture patterns and the comparison of the Pyrenees with other European ranges from different climatic and biogeographical regions.

Geochemical record of Lake Sabakty: Electrical conductivity and reconstruction of the Lateglacial and Holocene environments in the Southern Urals (Russia) steppe

Research subject. The Lake Sabakty sediments core, as a source of data on the Holocene and Lateglacial environments in the Southern Urals.Aim. To obtain a multiple regression model for quantitative reconstructions of the electrical conductivity of water based on the geochemistry of lake sediments and to reconstruct the Late Glacial and Holocene environments based on the study of the Lake Sabakty geochemical record.Materials and methods. After determination of correlations between the content of chemical elements in lake sediments and hydrochemical parameters of 107 Ural lakes, multiple regression models were obtained. Reconstructions were performed based on the results obtained by accelerator mass spectrometry (AMS 14C), 210Pb activity determination, and an analysis of chemical elements and organic matter contents in the sediment core.Results. Three multiple regression models using the concentrations of Na, Ca, Li, and Sr were obtained for electrical conductivity of water reconstruction. In the cold and dry Lateglacial (>12.0 ka cal BP), Lake Sabakty was a slightly brackish reservoir. During the transition from the Lateglacial to the Holocene (12–11.6 ka cal BP), the Lake Sabakty became more productive. In the Early (11.6–8.2 ka cal BP) and Middle (8.2–4.2 ka cal BP) Holocene, the electrical conductivity of water varied under the action of fluctuations in effective moisture. In the Late Holocene (4.2 ka cal BP – present), the Lake Sabakty became less saline due to an increase in effective moisture.Conclusions. The proposed multiple regression models enable rapid quantitative reconstructions of the electrical conductivity of water, which are particularly relevant for Lateglacial–Early Holocene sediments with a low number of microfossils. The Lake Sabakty geochemical record reflects global and regional climatic fluctuations, being more informative compared to the geochemical records of forest lakes in the Southern Urals. The decrease in the electrical conductivity of water of Lake Sabakty of approximately 7.9 and 4.2 ka cal BP coincides with similar data for several other lakes in the Urals.

Lateglacial and Early Holocene palaeoenvironmental change and human activity at Killerby Quarry, North Yorkshire, UK

ABSTRACTThe hunter‐gatherers that entered the British peninsula after ice‐retreat were exploiting a dynamic, rapidly changing environment. Records of vegetation change and human occupation during the Lateglacial to Early Holocene in northern Britain are more commonly found at upland and cave sites. However, recent research highlights many areas of the Swale–Ure Washlands that preserve extensive environmental sequences in low‐lying ice‐wastage basins, channels and depressions. The Lateglacial–Early Holocene environment of Killerby Quarry, North Yorkshire, is investigated here using a multi‐proxy approach of sedimentary ancient DNA (sedaDNA), pollen, sedimentological (geochemistry and portable optically stimulated luminescence), and rare and well‐preserved archaeology (Lavvu structures and lithics). Results show that the wetland basins and kettleholes were small lakes or ponds in the Lateglacial surrounded by sedge‐fen and birch woodland. A gradual (centennial scale) succession to reed‐swamp and then marsh is seen by the Early Holocene. This environment formed the resource‐scape for hunter‐gatherer transitory settlement in both the Lateglacial (Late Upper Palaeolithic) and Holocene (Early Mesolithic), attracted by the rich communities of pond‐related flora and fauna as well as easy strategic landscape access by way of the River Swale, an arterial route through the landscape connecting the North Sea Basin with the Pennine uplands via the palaeolakes around Killerby.

Corrigendum to “A high-resolution Lateglacial–Early Holocene tephrostratigraphy from southernmost Sweden with comments on the Borrobol–Penifiler tephra complex” [Quat. Geochronol. 67 (2022) 101239

Corrigendum to “A high-resolution Lateglacial–Early Holocene tephrostratigraphy from southernmost Sweden with comments on the Borrobol–Penifiler tephra complex” [Quat. Geochronol. 67 (2022) 101239

Environmental changes since 14 ka BP in the southernmost Kuril islands (North-Western Pacific) and regional correlation of events

• New data on climatic changes at the late Pleistocene-Holocene boundary for Kurils. • Climate fluctuations and volcanic ash-falls were mail drivers in lake-mire evolution. • The lake level was highest during warmer and humid climate of the Allerød. • Younger Dryas cooling in the Kuril Islands was less distinct than on the continent. • Pollen record vegetation changes on the land bridge at Late Glacial–early Holocene. Despite considerable progress in understanding Late Pleistocene and Holocene palaeoenvironmental changes worldwide, there are still very few such data for the Far East, and Kuril islands, in particular. Here, the sea level rise during the Late Glacial–Holocene transition was accompanied by a loss of the land connectivity culminating into the development of isolated islands. The ecosystems evolution and importance of isolation for vegetation dynamics on islands are still insufficiently understood. We investigated a unique natural record of environmental change since 14 ka has been recently discovered in lake–mire complex on Kunashir Island. The sediments include 12 tephra layers from Kunashir and Hokkaido volcanoes. The lake level was highest during warmer and humid climate of the Allerød. Diatom assemblages indicated the higher lake level between 12 730–12 160 cal yr BP. The first half of Younger Dryas was characterized by heavy snowfalls. Cooling attributed to the Younger Dryas in the Southern Kurils was less distinct than on the continent. The pollen assemblages recorded changes in vegetation on the land bridge. At the end of the Pleistocene large areas were occupied by birch forests and shrub pine. The broadleaf species first appeared at the end of Allerød. Starting from the Pleistocene-Holocene transition and during the early Holocene , the role of conifers sharply increased. In the middle Holocene the proportion of broadleaf trees in forests increased. Coniferous forests became abundant during the Little Ice Age. Short-tern climatic fluctuations correlate well with regional pattern, particularly with fluctuations of the moisture supply.

Late Glacial and Holocene Palaeolake History of the Última Esperanza Region of Southern Patagonia

We undertook multi-proxy analyses on two sediment cores from Lago Pato, a small lake basin at 51°S topographically separated from Lago del Toro in Torres del Paine (TdP), to provide insights into glacier dynamics and lake-level change in the TdP and Última Esperanza region over the last ∼30,000 cal a BP (30 ka). Lago Pato is situated in a region overridden by the Southern Patagonian Ice Field during the Last Glacial and in a transitional climatic zone of Southern Patagonia sensitive to seasonal- to millennial-scale changes in the Southern Hemisphere Westerly Winds (SWW). Results show that a deep ice-dammed and enlarged palaeolake encompassed Lago del Toro and Lago Pato c. 30–20 ka after the ice had retreated from local-Last Glacial Maximum (l-LGM) limits at c. 48–34 ka and during the build-up to the global-Last Glacial Maximum (g-LGM), c. 26–19 ka. Gaps in both sediment records between c. 20–13.4 ka and c. 20–10 ka suggest hiatuses in sediment accumulation during the g-LGM and Antarctic Cold Reversal (ACR) readvances and/or removal by lake lowering or flushing during the Late Glacial–early Holocene. The palaeolake level dropped from >100 m a.s.l. to ∼40–50 m a.s.l. towards the end of the ACR c. 13.4–13.0 ka, creating a shallower glaciolacustrine environment dammed by an ice tongue in the Estancia Puerto Consuelo–Última Esperanza fjord. Further lowering of the enlarged palaeolake level occurred when the ice thinned to <40 m a.s.l., eventually isolating Lago Pato from Lago del Toro and glaciogenic sediment input at c. 11.7 ka. After isolation, the ecology and water levels in Lago Pato became sensitive to regional climate shifts. The shallow, stable, and highly anoxic environment that developed after c. 11.7 ka is associated with weaker (or poleward shifted) SWW at 51°S and was replaced at c. 10 ka by an increasingly productive shallow-littoral lake with a variable lake-level and periodic shifts in anoxic-oxic bottom water conditions and ratios of benthic-planktonic diatoms. A more open Nothofagus forest, established at c. 8.6–7.5 ka, and more arid conditions c. 7.5–5.7 cal ka BP are linked to another phase of weaker (or poleward shifted) SWW at 51°S. More persistently wet conditions from c. 5.7 ka, with extensive closed Nothofagus forests and planktonic diatoms dominant, are associated with stronger (or equatorward shifted) SWW over 51°S. The abrupt return of benthic-to-tychoplanktonic diatoms after c. 3 ka reflects enhanced SWW at 51°S. Increasingly stable lacustrine and littoral wetland conditions established in the last ∼500 years reflect weaker SWW and lasted until recent decades.

A high-resolution Lateglacial–Early Holocene tephrostratigraphy from southernmost Sweden with comments on the Borrobol–Penifiler tephra complex

We present results from a cryptotephra investigation performed at a high resolution (0.5 cm) on sediments from Körslättamossen in southernmost Sweden. Six peak concentration levels were detected and extracted for geochemical analysis by electron probe microanalyser. Five of these levels were successfully analysed and we propose correlations to the Hässeldalen Tephra, the Vedde Ash, and the Laacher See Tephra (adding new analysis results for the first geochemically confirmed finding of the latter in Sweden), as well as an undetermined Borrobol-type tephra. The tephra identifications were combined with radiocarbon dated macrofossils in order to create an age model for the sampled sediments based on Bayesian methods. Stratigraphical and chronological results were found to concur with a previous study of the site and our results form the basis for discussion concerning the issues surrounding Lateglacial Borrobol-type tephras, of which we suggest further review in order to unlock these tephras’ full potential for Quaternary studies. • 5 cryptotephras detected in sediments from the Last Glacial–Interglacial Transition. • New geochemical data of the first confirmed Laacher See Tephra finding in Sweden. • Undetermined Borrobol-type tephra highlights the Borrobol–Penifiler tephra complex.

Vegetation response to rapid climate change during the Lateglacial–Early Holocene transition at Gola di Lago, southern Switzerland

Predicting the effects of ongoing climate warming on vegetation requires a long‐term perspective of past ecosystem dynamics. We therefore analysed the sedimentary record from the mire Gola di Lago (985 m a.s.l.) in southern Switzerland, to better understand the vegetation response to past rapid climate change. We present a high‐resolution pollen and plant macrofossil study from the Lateglacial to the Early Holocene (13 400–10 400 cal. a BP), a climatic transition that represents a close analogue to current global warming. The vegetation responses during this time match previously analysed palaeoecological sites south of the Alps. At the end of the Bølling‐Allerød interstadial, the site was surrounded by open larch forest. The beginning of the Younger Dryas was characterized by the local presence and rapid expansion of Pinus cembra, whereas the second part was dominated by Pinus sylvestris, Betula and Larix decidua. These vegetation dynamics agree well with independent climate data indicating a cold and dry start and a subsequent shift to slightly warmer climate. The following rapid temperature increase at the beginning of the Holocene resulted in an increase in forest density and the establishment of novel temperate vegetation assemblages, without major changes in species diversity. Noteworthy, during the Younger Dryas–Early Holocene transition, long‐lived cold‐adapted tree line species such as P. cembra and L. decidua persisted over several centuries, while open boreal forests dominated by P. sylvestris and Betula expanded, indicating high resilience to climatic changes. The results of Gola di Lago suggest that climate warming led to a significant change in vegetation communities through species range shifts. Our study also indicates that some species may potentially be able to locally persist under current global warming, forming novel vegetation assemblages with newly establishing species.

Toward a standardized procedure for charcoal analysis

AbstractSedimentary charcoal records are used for understanding fire as an earth system process; however, no standardized laboratory methodology exists. Varying sample volumes and chemical treatments (i.e., type of chemical for length of time) are used for the deflocculation and extraction of charcoal from sediment samples. Here, we present the first systematic assessment of the effect of commonly used chemicals on charcoal area and number of fragments. In modern charcoal the area of fragments was significantly different depending on the chemical treatment. We subsequently applied H2O2 (33%), NaClO (12.5%), and HNO3 (50%) to a late-glacial–early Holocene paleorecord and tested different sample volumes. The effects of the treatments were consistent between modern and fossil experiments, which demonstrates the validity of applying results from the modern experiment to the fossil records. Based on our experiments we suggest (1) H2O2 33%, especially for highly organic sediments; (2) avoidance of high concentrations of NaClO for prolonged periods of time, and of HNO3; and (3) samples of 1 cm3 provided typically consistent profiles. Our results indicate that charcoal properties can be influenced by treatment type and sample volume, thus emphasizing the need for a common protocol to enable reliable multi-study comparisons or composite fire histories.

Evidence of wildfire in the British Isles during the Last Glacial-Interglacial Transition: Revealing spatiotemporal patterns and controls

Charcoal records are now widely used to reconstruct past burning activity as there is an increasing global interest in understanding the complex interactions between fire, climate, vegetation and human activity. However, this topic has been relatively overlooked in the British Isles, as the region is generally thought to not support natural burning regimes. Here, for the first time, we present a synthesis of previously published charcoal data for 238 sites and demonstrate the widespread occurrence of charcoal in sediments that span the Last Glacial-Interglacial Transition (LGIT; c. 17−8.3 ka cal. BP) in the British Isles. Analysis is based upon a semi-quantitative analysis of the assembled dataset; the common patterns are identified and are considered in relation to independent reconstructions of climate, vegetation and anthropogenic activity. No causal relationships with vegetation are identified, while charcoal is also prominent during periods when archaeological evidence for human occupation of the British Isles is absent or scarce. Climate is very likely to have controlled the fire regimes during the LGIT. We conclude with ten research priorities to further advance our understanding of palaeofire drivers during the Lateglacial-Early Holocene.

Late Glacial-early holocene vegetation and environmental changes in the western Iberian Central System inferred from a key site: The Navamuño record, Béjar range (Spain)

A new record from a long sediment core (S3) in Navamuño (1505 m asl, western Iberian Central System) provides the reconstruction of the vegetation history and environmental changes in the region between 15.6 and 10.6 ka cal BP, namely during the Late Glacial and the early Holocene, using a multiproxy analysis (pollen-based vegetation and climate reconstruction, sedimentary macrocharcoals, loss-on-ignition, magnetic susceptibility and X-ray fluorescence (XRF) measurements). The results are then compared with other sequences from the Iberian Central System and the whole Iberian Peninsula in order to better understand the past dynamics of the main forest constituents. The pollen record shows a shift from open pine forests ∼15.6–14.7 ka cal BP (Oldest Dryas) to mixed open pine-birch woodlands ∼14.7–14.0 ka cal BP (Bølling). Woodlands were succeeded by a steppe-like landscape until ∼13.4 ka cal BP (Older Dryas), which was replaced again by high-mountain pine forests and riparian woodlands ∼13.4–12.6 ka cal BP (Allerød). A great development of cold steppe grasslands linked to the decline of birch woodlands is documented ∼12.6–11.7 ka cal BP (Younger Dryas). The early Holocene (11.7–10.6 ka cal BP) was characterized by a progressive reforestation of the study area by pine and birch forests in the highlands and oak woods in the lowlands. Temperate tree taxa (Carpinus betulus, Castanea sativa, Corylus avellana, Fraxinus, Juglans, Tilia, and Ulmus) were also common but likely at lower elevations. Pollen of Fagus sylvatica was already recorded during the Late Glacial and the early Holocene. The marked increasing local fire activity during the warmer and wetter Allerød oscillation could be related to a rise in tree cover, supporting the climatically driven character of these fires. Nevertheless, the strong increase in fire activity during the Younger Dryas would probably be related to growing tree and shrub mortality, as well as to the wet/dry biphasic structure of this stadial. The standard “Modern Analogue Technique” has been also applied to the Navamuño sequence to provide quantitative climate estimations for the Late Glacial and the early Holocene periods. This record is one of the few continental archives that show the climatic trend between the Late Glacial and the early Holocene in central Iberia, agreeing with many other regional records from the Western Mediterranean.

The Lateglacial-Early Holocene dynamics of the sedimentation environment based on the multi-proxy abiotic study of Lieporiai palaeolake, Northern Lithuania

New data were obtained from the sedimentary sequence study of Lieporiai palaeolake, Northern Lithuania, employing a multi-proxy abiotic approach, for the description of the Lateglacial-Early Holocene palaeoenvironmental dynamics in the basin. The study reveals significant differences in sediments deposited in the Lateglacial, at the end of Lateglacial/Early Holocene and in the Late Holocene time periods. Six main environmental stages are described. After glacial retreat, the formed landscape was re-organized by very fast currents that might have appeared later than previously thought. Rapid water flow stabilized and lacustrine sedimentation began together with the appearance of scarce pioneer vegetation shortly before 14 600 cal yr BP, (GI-1e). The development of the lake with mostly undisturbed sedimentation continued up to the final stages of the Lateglacial Interstadial. The warm period caused maximum precipitation of Ca and Sr carbonates, which strongly affected sediment saturation with other components. Increase in humidity in the later Lateglacial Stadial (GS-1) period is indicated by the abrupt appearance of the coarser-sized mineral matter accompanied by weathering elements, i.e. Ti, Al, Si, Mg, and the early immigration of Picea. About 11 500 cal yr BP, the mineral matter input started decreasing, and stabilization of the climate regime began about 10 200 cal yr BP. (A)biotic proxies highlight slow sedimentation mechanisms that recover shallow- and trophic-lake stages. The Lieporiai palaeolake record clearly shows the sedimentation hiatus between the Early and the Middle Holocene. Further stages are characterized by paludification processes. Finally, peat accumulation was interrupted by humans.

How dry was the Younger Dryas? Evidence from a coupled <i>δ</i><sup>2</sup>H–<i>δ</i><sup>18</sup>O biomarker paleohygrometer applied to the Gemündener Maar sediments, Western Eifel, Germany

Abstract. Causes of the Late Glacial to Early Holocene transition phase and particularly the Younger Dryas period, i.e. the major last cold spell in central Europe during the Late Glacial, are considered to be keys for understanding rapid natural climate change in the past. The sediments from maar lakes in the Eifel, Germany, have turned out to be valuable archives for recording such paleoenvironmental changes. For this study, we investigated a Late Glacial to Early Holocene sediment core that was retrieved from the Gemündener Maar in the Western Eifel, Germany. We analysed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of leaf-wax-derived lipid biomarkers (n-alkanes C27 and C29) and a hemicellulose-derived sugar biomarker (arabinose), respectively. Both δ2Hn-alkane and δ18Osugar are suggested to reflect mainly leaf water of vegetation growing in the catchment of the Gemündener Maar. Leaf water reflects δ2H and δ18O of precipitation (primarily temperature-dependent) modified by evapotranspirative enrichment of leaf water due to transpiration. Based on the notion that the evapotranspirative enrichment depends primarily on relative humidity (RH), we apply a previously introduced “coupled δ2Hn-alkane–δ18Osugar paleohygrometer approach” to reconstruct the deuterium excess of leaf water and in turn Late Glacial–Early Holocene RH changes from our Gemündener Maar record. Our results do not provide evidence for overall markedly dry climatic conditions having prevailed during the Younger Dryas. Rather, a two-phasing of the Younger Dryas is supported, with moderate wet conditions at the Allerød level during the first half and drier conditions during the second half of the Younger Dryas. Moreover, our results suggest that the amplitude of RH changes during the Early Holocene was more pronounced than during the Younger Dryas. This included the occurrence of a “Preboreal Humid Phase”. One possible explanation for this unexpected finding could be that solar activity is a hitherto underestimated driver of central European RH changes in the past.

Evidence for distal transport of reworked Andean tephra: Extending the cryptotephra framework from the Austral volcanic zone

Abstract Cryptotephra deposits (non-visible volcanic ash beds) may extend thousands of kilometres and provide valuable chronological isochrons. Here, we present a Lateglacial-early Holocene (c. 16,500 cal yr BP-6000 cal yr BP) tephrostratigraphy from Hooker's Point, East Falkland, South Atlantic. This period spans the last glacial termination across the southern mid-latitudes, a time period during which the palaeoenvironmental record is poorly resolved in southern South America and the South Atlantic. The development of a regional tephrostratigraphy will provide chronological constraint for palaeoenvironmental records from this period. Two cryptotephra deposits from Hooker's Point are linked with Mt. Burney, including the early-Holocene MB1 tephra, while a third is likely to be derived from the R1 eruption of Reclus volcano. The high shard abundance of these cryptotephra deposits suggests they extend further into the Southern Ocean, and may act as regional stratigraphic markers during the Lateglacial. Further peaks in shard abundance are composed of detrital glass (tephra not derived from primary air fall events), with mixed shard morphologies and geochemically heterogeneous glass populations. This detrital glass is likely to have been repeatedly reworked by wind action in the Patagonian Steppe before final deposition in the Falkland Islands. The high abundance of detrital glass in the Hooker's Point sequence suggests long distance transport of reworked tephra is common in this region, and highlights the need to carefully analyse cryptotephra deposits in order to avoid incorrectly describing reworked tephra as new isochrons. A temporal pattern of shard abundance is apparent in the Hooker's Point sequence with a reduction/absence of shards between 14,300–10,500 cal yr BP.

Palaeoecological evolution of a spring-fed fen in Pawłów (eastern Poland)

A continuous record of sedimentation in spring-fed fens makes them suitable for detailed palaeoenvironmental studies. A newly investigated cupola spring-fed fen (Pawłów site), located in the Lublin chalkland, eastern Poland, was the object of our study. This special karst region is characterised by the occurrence of Upper Cretaceous carbonate rocks in the substratum. Sedimentological observations indicated strong variability of biogenic-carbonate series in the deposits (=peat-tufa rhythmite), reflects changes of accumulation conditions (oxidising versus reducing), resulting from alternate occurrence of warmer and cooler periods. Difficulties in pollen analysis due to oxidising conditions necessitate a multidisciplinary approach for palaeoenvironmental reconstruction. We used a multidisciplinary approach (sedimentological, palaeobotanical, geochemical analyses and radiocarbon dating) to determine the main evolutionary stages of this unique fen ecosystem and to discuss the role of local or/and regional factors in its development. Pollen and plant macrofossil analyses, supported by radiocarbon dating, proved that the bottom part of the cores represents the Late Glacial–Early Holocene stages of the fen development. A comparative analysis of palaeoenvironmental data showed close resemblance between the Pawłów fen and the earlier studied fens in eastern Poland and Central-Eastern Europe, and the connection between their development and supraregional hydrological-climatic factors. The results indicated also the influence of the morphological position of such a type of ecosystem on the development of a continuous deposit succession. The occurrence of a river valley in close proximity of the Pawłów site resulted in the lack of tufa deposits from the Atlantic period, because of an erosional phase in the river valley.

Svalbard glaciers re‐advanced during the Pleistocene–Holocene transition

Despite warming regional conditions and our general understanding of the deglaciation, a variety of data suggest glaciers re‐advanced on Svalbard during the Lateglacial–early Holocene (LGEH). We present the first well‐dated end moraine formed during the LGEH in De Geerbukta, NE Spitsbergen. This landform was deposited by an outlet glacier re‐advancing into a fjord extending 4.4 km beyond the late Holocene (LH) maximum. Comparing the timing of the De Geerbukta glacier re‐advance to a synthesis of existing data including four palaeoclimate records and 15 other proposed glacier advances from Svalbard does not suggest any clear synchronicity in glacial and climatic events. Furthermore, we introduce six additional locations where glacier moraines have been wave‐washed or cut by postglacial raised marine shorelines, suggesting the landforms were deposited before or during high relative sea‐level stands, thus exhibiting a similar LGEH age. Contrary to current understanding, our new evidence suggests that the LGEH glaciers were more dynamic, exhibited re‐advances and extended well beyond the extensively studied LH glacial expansion. Given the widespread occurrence of the LGEH glacier deposits on Svalbard, we suggest that the culmination of the Neoglacial advances during the Little Ice Age does not mark the maximum extent of most Svalbard glaciers since deglaciation; it is just the most studied and most visible in the geological record.

Mediterranean monk seal hunting in the regional Epipalaeolithic of Southern Iberia. A study of the Nerja Cave site (Málaga, Spain)

During the Late Glacial–Early Holocene transition Southern Iberia has an extensive record of Palaeolithic coastal sites, wich have been preserved due thanks to the morphology of the continental shelf. This is was a period with rapid palaeoclimatic oscillations and changes in sea level. However, the sites show an apparent continuity in technology and subsistence trends, although human groups made increasingly intense use of marine resources. In this paper we will focus on the study of Mediterranean seal remains from the Vestíbulo hall of Cueva de Nerja (Málaga, Spain), unit NV4, dated 12,990–11,360 cal. BP. The presence of these bones at the site are interpreted as direct exploitation of seals by humans, who processed different parts of the animal like the flesh, blubber and skin. These data allow us to assess the changing role of marine mammals in the regional Palaeolithic economy.