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Detailed knowledge of the periglacial flora is essential to assess the vegetation dynamics in deglaciated regions of northern and north eastern Europe, previously covered by the ice sheet of the Late Weichselian Glaciation. Therefore, the territory of Belarus, which stretches in the periglacial zone of the Last Glaciation and the most part of which was free of ice during the Last Glacial maximum, is off particular importance in analysing the postglacial floral establishment and the subsequent vegetation dynamics in this part of the continent. In this study, results of palaeobotanical (pollen and plant macrofossil), lithological (measurements of magnetic susceptibility, MS) and isotopic (14C) investigations were obtained to fill the existing gap in reconstructing the peculiarities of the terrestrial and aquatic vegetation dynamics throughout the Lateglacial - Early Holocene period in the central Belarus. The investigated sediment profile, comprising organically enriched gyttja at 13,400–13,100 cal yr BP, carbon enriched and sandy gyttja at 13,100–9700 cal yr BP and unconsolidated mud after 9500 cal yr BP, provides clear evidence proving the flourishing of a pine-birch predominated forest with occasional spruce stands during the Allerod in area. Three occasions of change in the vegetation structure were noted within the Younger Dryas, i.e. 12,900–12,700 cal yr BP, 12,200–12,000 cal yr BP and 11,900–11,700 cal yr BP, suggesting negative climatic excursion taken place in area and facilitating flourishing of a Picea-predominating forest that culminated at about 12,300 and 12,000 cal yr BP. Pollen record suggests the Early Holocene vegetation shifts occurring at about 11,300–11,200 cal yr BP, 10,800–10,600 cal yr BP and 10,300–10,100 cal yr BP evidence the general response to the global-scale climatic events i.e. Preborael Oscillation or “10,2 ka” while fluctuations triggered by local or regional-scale climatic events have been identified as well. About 10,800–10,700 cal yr BP, formation of the forest with an increasing representation of thermophilous taxa (Ulmus, Tilia, Quercus) started in area.

Lammefjorden is a reclaimed fjord in north-west Sjælland, Denmark. Sediment cores from the area were collected to study its development after the last deglaciation, in particular the sea-level history. Late glacial and Early Holocene lake and bog deposits occur below marine deposits. Sparse late glacial fossil assemblages indicate tree-less environments with dwarf-shrub heaths. Early Holocene deposits contain remains of Betula sec. Albae sp. and Pinus sylvestris, which indicate open forests. The wetland flora comprised the calciphilous reed plant Cladium mariscus and the water plant Najas marina. Marine gyttja from basins is characterised by sparse benthic faunas, probably due to high sedimentation rates. In some areas, shell-rich deposits were found, with large shells of Ostrea edulis, indicative of high summer temperatures, high salinity and strong tidal currents. A marine shell dated to 6.7 cal. ka provides a minimum age for the marine transgression of Lammefjorden.

The last British-Irish Ice Sheet (BIIS) created a landscape with many sedimentary basins that preserve archives of paleoenvironmental and paleoclimatic change during the Last Glacial-Interglacial Transition (LGIT; ~ 18-8 ka BP). The typical lithostratigraphic succession of these archives is composed of minerogenic/allogenic sediments formed during cold climatic conditions and organic-rich/authigenic sediments during warmer climates. This paper presents a multi-core lithostratigraphy compiled from the extant lake and surrounding basin at Llangorse Lake, south Wales, a basin lying within the southernmost limits of the last BIIS. This lake contains one of the longest continuous terrestrial sediment successions in the UK. Uncertainty previously existed concerning the presence and distribution of sediments at the site related to the Windermere Interstadial (~ 14.7 to ~ 12.9 ka BP) and Loch Lomond Stadial (~ 12.9 to 11.7 ka BP). A new borehole survey demonstrates that LGIT-age sediments are present at the site with nekron mud (gyttja), corresponding to the Lateglacial Interstadial, deposited in the deeper part of the lake waters and that these deposits are equivalent in age to marl deposits found at shallower depths at the margins of the basin. These deposits are associated with warmer conditions experienced during the Windermere Interstadial and Holocene, whilst minerogenic-rich sediments were deposited during the colder climatic conditions of the Dimlington Stadial and the Loch Lomond Stadial with rangefinder radiocarbon dates confirming this attribution. A model of lake level changes shows that drainage of the Dimlington Stadial glacial lake caused the largest fall, but there was also a further, smaller lake level fall at the end of the Windermere Interstadial and/or the start of the Loch Lomond Stadial, before the level rose in the early Holocene. The lithostratigraphic results presented here form the framework for further paleoenvironmental and paleoclimatic research at Llangorse Lake.

This paper presents the first result of a study of two long-term natural archives in the southwestern part of the Western Siberian Plain. Bchron age models based on 17 AMS dates allowed us to determine a chronology of changes in properties of lake and peat deposits. Significant changes in the Holocene were identified according to geochemical indices, accumulation rates, and compositions of the plant macrofossils of sediment cores in Lake Kyrtyma and Oshukovskoe peat bog. Sediments with a low content of organic matter and maximum weathering accumulated in the Late Glacial, below the border of the Holocene. The transition to the Holocene manifested as a black organic gyttja with ostracods and marked warming ∼12–11.2 ka BP. At about 11.2–10.1 ka BP it was replaced by the Preboreal oscillation. Subsequent changes in lake sedimentation were associated with general warming and an unstable hydrological regime. An increase in humidification ∼8.2 ka BP was reflected by lake level rise and contributed to swamping of the watersheds. The aridest Holocene phase at ∼7.1–5.5 ka BP was reliably recorded by geochemical data, but poorly reflected in the stratigraphy of both profiles. Subsequent cooling and the resulting decrease in evaporation began at ∼5.5–4.9 ka BP. A pronounced cardinal shift in sedimentation conditions due to a gradual increase in precipitation was recorded at ∼4.9–2.8 ka BP, though short-term fluctuations towards dryness were also marked at ∼3.5–3.3 ka BP. The most significant increase in humidification and cooling began at 2.8 ka BP. Geochemical indices in the lacustrine sediments are climate sensitive and allowing us to obtain enough reliable data associated with changes in sedimentation environments. The stratigraphy of peat reflected the nuances of climatic changes less clearly and primarily demonstrated the stages of bog self-development; however, sphagnum peat provided a better-resolution record.

Here we present results of high-resolution palaeoecological studies of the organic deposits accumulated in Lake Jaczno, located in the north-eastern Poland. Plant macrofossils and malacological analyses complimented by radiocarbon dating (AMS) were undertaken to reconstruct Early Holocene succession of the pioneer wetland plants and molluscs in the lake ecosystem. Numerous presence of charcoal pieces (>1 mm) and fungal remains (sclerotia) in the peat layer accumulated on the mineral ground document dry habitat what coincides with warm and dry climate conditions in the early Holocene recorded in this part of Europe. Change to lacustrine environment documented by accumulation of the carbonate gyttja on the highly decomposed peat layer took place ca. 10,500 cal yr BP. The current morphology of Lake Jaczno, in which several basins can be distinguished, suggests that different age of sediments accumulated at the bottom part at our sampling sites might result from different sizes of the buried dead ice blocks, and their heterochronous final melting. The first aquatic plants that appeared in Lake Jaczno were Chara sp., Ceratophyllum demersum and Nymphaea alba. The appearance of Cladium mariscus in Lake Jaczno ca. 9400 cal yr BP was synchronous with the substantial spread of this plant in this region which coincided with increased climate humidity. The first molluscan species that colonized the lake ecosystem were Gyraulus crista and Bithynia tentaculata, species living on macrophytes, and Valvata piscinalis, typical for habitats characterized by a thick layer of plant detritus.

Publisher's version (útgefin grein)., Sediment cores from Kløverbladvatna, a threshold lake in Wahlenbergfjorden, Nordaustlandet, Svalbard were used to reconstruct Holocene glacier fluctuations. Meltwater from Etonbreen spills over a threshold to the lake, only when the glacier is significantly larger than at present. Lithological logging, loss-on-ignition, ITRAX scanning and radiocarbon dating of the cores show that Kløverbladvatna became isolated from Wahlenbergfjorden c. 5.4 cal. kyr BP due to glacioisostatic rebound. During the Late Holocene, laminated clayey gyttja from lacustrine organic production and surface runoff from the catchment accumulated in the lake. The lacustrine sedimentary record suggests that meltwater only spilled over the threshold at the peak of the surge of Etonbreen in AD 1938. Hence, we suggest that this was the largest extent of Etonbreen in the (mid-late) Holocene. In Palanderbukta, a tributary fjord to Wahlenbergfjorden, raised beaches were surveyed and organic material collected to determine the age of the beaches and reconstruct postglacial relative sea level change. The age of the postglacial raised beaches ranges from 10.7 cal. kyr BP at 50 m a.s.l. to 3.13 cal. kyr BP at 2 m a.s.l. The reconstructed postglacial relative sea level curve adds valuable spatial and chronological data to the relative sea level record of Nordaustlandet., Sveinn Brynjólfsson and Sara Mollie Cohen are thanked for field assistance. Fieldwork and radiocarbon dates were funded by the Carlsberg Foundation (CF14-0756 to Schomacker) and Department of Arctic Geology, The University Centre in Svalbard (UNIS), respectively. Geospatial support was provided by the Polar Geospatial Center, and DEM(s) were created from DigitalGlobe, Inc., imagery and funded under National Science Foundation awards 1043681, 1559691, and 1542736. We thank Ole Bennike, Svend Funder, Antony Ruter, and Peter Ilsøe for macrofossil identification and lab assistance. The manuscript benefited from constructive review comments from Andy Emery. The publication charges for this article have been funded by a grant from the publication fund of UiT The Arctic University of Norway.

This study presents 1) the results of a stable isotope and subfossil Cladocera analyses of lacustrine sediments from Maliszewskie Lake (E Poland) and next 2) different reaction of the lake environments depending on the lake's localization. Maliszewskie Lake is located in North Podlasie Lowland ca. 30 km to the south of the Vistulian ice sheet limit. The approximately 4.80-m-thick sediments (Maliszewo I profile) are mainly comprised of calcareous gyttja covered by peat and organic detritus gyttja. Pollen analysis documents that the sediments accumulated from the Late Glacial (Allerod period) to recent times. Based on the results of stable isotope and subfossil Cladocera analyses of sediments, the lake environmental changes were reconstructed. A positive trend in δ18O and δ13C values documents a gradual climatic warming. The fluctuations of the oxygen isotopic values suggest the multiple oscillation of water level due to a change in the evaporation/precipitation ratio. The subfossil cladoceran fauna in the Maliszewo I profile is represented by 21 species belonging to five families. Three zones of Cladocera development were distinguished. The Cladocera species indicate the initial oligotrophic status of the lake and its subsequent increase of trophic status. Currently, Maliszewskie Lake is a very shallow, declining reservoir. The initial period of its existence probably saw its maximal depth. In presented studies we compared our results with data from three other sites documenting the reaction of the lake environment during the Late Glacial and Holocene transformation. At that time we observed different reactions to the climate amelioration. In the northern, postglacial lakes, the Holocene warming at first provoked an input cold melting water characterized by more negative oxygen isotope values and then a rise in water temperature. In the lakes further away from the glaciation border (periglacial lakes), the increase in water temperature, documented by e.g. more positive oxygen isotopic immediately occurred. The climate warming is commonly manifested by a significant increase of number of species and individuals of Cladocera.

While recent landscape changes can be usually easily read through accessible morphological features, relatively ancient processes can be difficult to detect as the associated morphologies and deposits are often buried below younger sediments. With the aim of understanding the evolution of the distal Venetian-Friulian Plain (NE Italy) after the Last Glacial Maximum (LGM), this work presents the analysis performed on a dataset of ca. 2300 mechanical and hand-made cores, which allowed a detailed reconstruction of the formation and evolution of an incised valley, now almost completely filled and with little to absent morphologic expression. Such valley, up to 1.2 km wide, with a depth of 20 m below the LGM alluvial plain and traced for a length of 25 km, is the result of the complex interplay between minor spring-fed rivers and the Tagliamento River. The detailed characterization of the infilling allowed to identify two main phases in the valley evolution. The first one is related to the activity of the paleo Tagliamento River and led to the deposition of a 10 m thick gravelly unit (ca. 19–9.5 ka cal BP). The second phase, which followed a disconnection of the Tagliamento, is linked to the Holocene marine transgression and led to the formation of a lagoon environment within the valley and to the deposition of a ca. 15 m thick unit of lagoon muds (ca. 8 ka cal BP - historic time). This latter unit lays on top of gyttja deposits, indicating for the first time in this area the presence of widespread lacustrine environments in the Early Holocene. This work presents an in-depth analysis on the evolution of a distal plain incised valley, from its formation to its final filling, providing at the same time the means to describe the development of the entire alluvial plain landscape, spanning from the end of the LGM to the middle Holocene. We present new data on the paleoenvironmental and morphologic evolution of the Venetian-Friulian Plain area as a consequence of the interplay between autogenic forces and sea-level rise. Our study allowed to understand the importance of both Alpine rivers and groundwater-fed streams in the formation of large incised valleys in the coastal sector of the whole Venetian-Friulian Plain. Finally, as during the transgressive phase the upstream sediment input in the valley was almost absent, this study provides insights into facies and architecture of a rare example of downstream-controlled filling of an incised valley.

The Rozprza stronghold functioned as a seat of a noble family since at least the early14th century AD in the form of the motte-and-bailey residence. The remains of the residence are situated in the central part of mid-Luciąza River valley, on the river terrace remnant adjoining a strongly expanding floodplain. The situation and state of preservation give a unique opportunity to conduct research that explain the construction process, detailed history of the medieval moat and palaeoenvironmental reconstruction of the valley floor. Radiocarbon and dendrochronological dating and analysis of artefacts confirmed 14th century age of the moat. Organic deposits (gyttja, peat and organic mud) of moat fill allowed for a set of multiproxy analyses based on sediment cores. The research results indicate shallow water with brief episodes of in-wash in the first stage (13th-14th c. AD), followed by a transformation into telmatic habitat in the second phase of the moat development from 16th-17th c. AD. The deposition of overbank alluvium took place within the moat ditch system as late as the 18th and/or 19th c. AD. We studied the development of this moat environment in the context of valley floor changes.

Diatoms and sediments were examined in a 530 cm core from Ishiba Ngandu, Zambia, a lake formed by gentle downwarping. Diatom zone D (>20 cal ka BP) was mostly sand with abundantAulacoseiraandEunotia, suggesting a shallow lake perhaps kept fresh by spring inputs and lake discharge, except during deposition of the lowermost 66 cm. Gyttja deposition between about 22 and 20 cal ka BP suggested a deeper lake and a wetter climate, perhaps because the Congo Air Boundary (CAB) was farther southeast relative to modern times. The next zone, zone C (about 20–19 cal ka BP), was sand with abundantAchnanthidiumandEunotiabut very few planktonic diatoms, apparently representing very shallow water and an arid period without the CAB. The gyttja and diatoms in zone B (19–4 ka) suggested an increase in moisture when the CAB returned. Zone A (4–0 cal ka BP) was dominated by the planktonicAulacoseira(>89%), suggesting an increase in wind-driven mixing. Uniquely, Ishiba Ngandu likely has been relatively moist since the last glacial maximum, matching pre-Holocene wetness in Botswana but not its Holocene aridity; evidently the climate here had switched to that of East Africa.

Despite recent progress in understanding high-latitude climate variability, paleoclimate records are scarce from the Alaskan Arctic. We conducted isotopic and sediment analyses at Wahoo Lake to infer Holocene climate variability in northeastern Alaska. Water δ18O and δD values from the lake and its inlet/outlet streams suggest that winter precipitation dominates modern water inputs and that evaporation has limited influence on the lake’s hydrological budget. The isotopic composition of Pisidium exhibits marked variations during the past 11,500 years, with δ18O ranging between −18.7‰ and −16.2‰ and δ13C between −7.1‰ and −2.3‰ (Vienna Pee Dee Belemnite (VPDB)). Elevated δ18O and sediment composition from 11.5 to 8.9 kcal. BP suggest evaporative 18O enrichment and arid conditions. Rising lake levels are evidenced by the disappearance of Pisidium and a transition to low-carbonate gyttja ca. 6.3 kcal. BP and by the onset of sediment deposition on an adjacent shelf by 5.3 kcal. BP. These changes coincided with enhanced effective moisture in interior and southern Alaska as inferred from lake-level records and may be related to broad-scale atmospheric circulation changes. In the shelf sediments, carbonate abundance increases markedly at 3.5 kcal. BP, and δ18O increases from −18.0‰ to −16.5‰ at 2.1 kcal. BP, possibly resulting from increased temperature and/or summer precipitation. After 2.1 kcal. BP, δ18O fluctuates with an overall decreasing trend to −17.2‰ at 0.9 kcal. BP. Late-Holocene variations in our δ18O record display coherent patterns with regional glacier fluctuations at centennial to millennial scales, suggesting that δ18O minima were related to a combination of low temperatures and enhanced winter snowfall. Holocene variations in organic matter abundance at Wahoo Lake also show broad similarities to total solar irradiance, implying that suborbital solar variability played a role in modulating regional climate and aquatic productivity.

Marine interglacial deposits are fairly common and widespread in Denmark, but so far none have been reported from the Herning area in central Jylland. In 2014, the Geological Survey of Denmark and Greenland (GEUS) received samples at one metre intervals from a borehole at 55°59.3´N, 8°56.6´E (elevation 27.56 m above sea level), at Hesselvigvej 7 near Kibæk in central Jylland (Fig. 1). The succession consisted of Miocene and Quaternary deposits. The Quaternary part was dominated by glaciofluvial sand and a single till bed, but it also contained a marine clay unit (16–21 m depth, 6.5–11.5 m a.s.l.). This marine clay contained spines of the sea-urchin Echinocardium cordatum, a boreal species known from Eemian and Holocene deposits from Denmark, but unknown from interstadial deposits. A lacustrine unit between 26 and 33 m depth (5.5 m b.s.l. to 1.5 m a.s.l.) consisted of clay, calcareous-rich gyttja and diatomite. Because Quaternary marine deposits are unexpected in this part of Denmark, we report here on analyses of pollen from the lacustrine unit and foraminifera from the marine unit, and we compare these with some interglacial records from Jylland.

WOS: 000377882700006, Lake Neor is the largest lacustrine basin in the high mountains of the Middle East, at 2500 m altitude in the Alborz belt. This lake of Holocene age is a shallow, fresh water body of glacial origin with ca 4 km(2) surface area and a 40 km(2) drainage area. Its sedimentary sequence comprised of peat and gyttja consists of >10 m infill, which is fairly thick for such a lake. Autochthonous organic matter is limited in and around the lake except for small areas at the northern and southern ends. Inorganic constituents of the infill sediment include a significant amount of fine-grained calcite, dolomite and mica particles that are exotic to the catchment. They do not occur in the source rocks, as the drainage area of the lake is composed of only andesites and trachyandesites of Eocene age. In addition, the uppermost part of the infill includes abundant fine-grained charcoal particles derived from large forest fires perhaps derived as far as the Mediterranean region. As shown by the present meteorological records, the sediment of Lake Neor is under aeolian control during dust storms; this is leading to a considerable amount of deposition air-borne particles. The infill of some lakes, particularly those in highlands, may have contain an important aeolian component and thus they cannot be used directly for the interpretation of the evolution of the palaeogeography without taking into consideration the role of dust storms on deposition. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved., Ankara University [12B434002]; [1227], The study has been supported by a research project of Ankara University (no 12B434002). Figures were drawn by Yasar Suludere. Water analyses of the lake were provided by the Ardabil Directorate for Environment Protection of Iran. Stephen Kershaw and Lorna Anguilano from Brunel University London critically read the original version. Mike Turner (Brunel University London) has kindly revised the English of the manuscript. Authors are grateful for all support. The publication is a contribution to the INQUA QuickLakeH project (No 1227).

High resolution X-ray fluorescence (XRF) is presented as a robust palaeoclimatic proxy, suitable for use on Late Pleistocene to Holocene sediments located in a volcanic crater on the Atherton Tableland in northeastern Queensland, Australia. The proxy allows identification of wet and dry shifts in a complex sedimentary sequence comprised of peat, gyttja, laminated organic rich muds and fine clastic silt-rich sediments. Significant correlation is found between the XRF record and other proxies including magnetic susceptibility, humification, grain size, macrocharcoal, δ13C and C/N and pollen. Sixteen wetter periods are identified in the 37 ka sedimentary record for Bromfield Swamp. Three wetter periods commence in late Marine Isotope Stage 3, nine in the early glacial, one in the late de-glacial and four in Holocene. Nineteen drier periods are identified, four in late MIS 3, seven in the early glacial, one during the LGM, one in the late de-glacial period and six in the Holocene. The XRF record for Bromfield Swamp is specifically used to identify periods of abrupt climate change. Marked changes in effective precipitation are detected at 32,690, 30,080, 24,660, 21,870, 11,880, 10,020, 9170 and 5120 cal. yr BP. The detection of these abrupt climate events may allow correlation with records from terrestrial sites across the Southern Hemisphere and potentially, the Northern Hemisphere.

A unique geological process of extrusion of lagoon marl from beneath massive migrating sand dunes is characteristic for large segments of the Curonian Spit – a ~100-km-long sandy barrier that separates the Curonian Lagoon from the Baltic Sea. Exposures of a composite set of Holocene organic sediments such as gyttja, clayey gyttja and gyttja clay, collectively referred to as ‘lagoon marl’, are common along the northern half of the lagoon coast of the spit. The marl outcrops rise up to 3–4 m above the lagoon level and owe their origin to extrusion from their 7–8 m in situ depth beneath the present regional water table. New detailed investigations of the Baltic Sea bottom along the southern half of the Curonian Spit using side-scan sonar, a multibeam echosounder, seismic imaging, sediment sampling and video observations allowed identification and mapping of a unique underwater landscape formed by extensive outcrops of laminated and folded lagoon marl at water depths of 5–15 m. The combined onshore–offshore database indicates that relict lagoon marl was deformed, compacted and dehydrated by a massive dune-covered coastal barrier migrating landward (retrograding) over these sediments during the Littorina Sea transgression in a processes termed ‘dune tectonics’. Spatial analysis of the relict sediments traced in offshore geophysical data helped to constrain the rates of the southeast migration of the dune massif. A conceptual model is presented to explain the present context of marl exposures above the regional water table, as well as the occurrence of relict lagoon marl extrusions (diapirs) on the underwater marine slope of the Curonian Spit.

Pollen, spore, macrofossil and carbon data from a peatland near Cordova, Alaska, reveal insights into the climate–vegetation–carbon interactions from the initiation of the Holocene, c. the last 11.5 ka, to the present (1 ka = 1000 calibrated years before present where 0 = 1950 CE). The Holocene period is characterized by early deposition of gyttja in a pond environment with aquatics such as Nuphar polysepalum and Potamogeton, and a significant regional presence of Alnus crispa subsp. sinuata. Carbon accumulation (50 g/m2/a) was high for a short interval in the early Holocene when Sphagnum peat accumulated, but was followed by a major decline to 13 g/m2/a from 7 to 3.7 ka when Cyperaceae and ericads such as Rhododendron (formerly Ledum) groenlandicum expanded. This shift to sedge growth is representative of many peatlands throughout the south-central region of Alaska, and indicates a drier, more evaporative environment with a large decline in carbon storage. The subsequent return to Sphagnum peat after 4 ka in the Neoglacial represents a widespread shift to moister, cooler conditions, which favored a resurgence of ericads, such as Andromeda polifolia, and increased carbon accumulation rate. The sustained Alnus expansion visible in the top 10 cm of the peat profile is correlative with glacial retreat and warming of the region in the last century, and suggests this colonization will continue as temperature increases and ice melts.

This study presents the results and interpretations of biological (floral and faunal) and geochemical (isotopic and chemical element composition) investigations of the Late Glacial and Holocene sediment accumulated in the Kaniewo palaeolake. These data allowed us to determine the indicators of environmental changes in this lake ecosystem, such as zooplankton and vegetation development, trophic state, water temperature, and water level. We documented the three cold periods (Oldest, Older, and Younger Dryas) separated by two warm periods (Bolling, Allerod). Additionally, we found traces of cold oscillations within the Allerod, lasting approximately 150 years, probably the Intra-Allerod-Gerzensee oscillation, recorded in western and southern Europe. Our data show that sediment accumulation began at the end of the Oldest Dryas period before ca. 13,900 yr cal BP. The top of the studied sediments represented the transition from the Late Glacial to the early Holocene (Preboreal period, ca.10,500 yr cal BP). The lithology of the sediments changed from silty sands at the bottom, then calcareous detritus gyttja partially interbedded by lake marl to peat at the top. Organic matter occurring in the deposits reflects algae and terrestrial sources. In the cold periods, small number of both Cladocera individuals and species (e.g. Bosmina (E.) longispina, Chydorus sphaericus, Alona affinis), corroborate the unfavourable conditions for the development of zooplankton. Cladocera species indicated the initial oligotrophic status of the lake and the subsequent increase in trophic status. Plant and animal macrofossils indicate initial shallow lake ecosystem. Chara meadow developed at the bottom of the lake with a belt of vascular plants (Carex sp., Hippuris vulgaris, Scirpus sp.) in the littoral zone of the lake. Rich shallow vegetation was accompanied by animals, such as Mollusca (e.g. Valvata piscinalis, Pisidium obtusale, Bithynia tentaculata) and Oribatidae sp., Cristatella mucedo, and Plumatella type.

The results of lithological analysis, diatom analysis and radiocarbon dating of bottom sediments from the basin of a lake located at an elevation of 17 m above sea level near the Teriberka settlement (Barents Sea coast, Kola Peninsula) are presented. The stages of the lake evolution were revealed based on a comprehensive investigation of its bottom sediments. The lake basin was covered by sea at the end of the Pleistocene. The lake became isolated from the sea approximately 11500 cal. yrs BP, but was re-filled with sea water after 10400 cal. yrs BP due to the Tapes transgression. In lower part of the Tapes sediments, there is a disturbance of the sediment sequence, represented by a mixture of sand, gyttja and plant residues. According to radiocarbon dates, this disturbed hori­zon was deposited between 10400 and 8200 cal. yrs BP. An abrupt increase in the con­tent of marine diatoms was found in this horizon. The disturbed sediments have possibly formed as a result of the Storegga tsunami. When the horizon of tsunamigenic sediments was forming, the sea level was slightly above the threshold for discharge from the lake (ca. 18 m above modern sea level). The second local event (tsunami?) occurred after 8220 cal. yrs BP, when the coastline was already below the lake threshold. As a result of this event, an interlayer of sandy sediments formed in the bottom sediments within gyttja.

Multi-proxy studies of the sediment cores and acoustic profiles from Mecklenburg Bay display a more detailed picture of the evolution of the environment in the Holocene. Studies of diatoms, geochemistry, grain size and radiocarbon dating clearly reveal the age and character of freshwater and marine transgressions and regressions. After the final regression of the Baltic Ice Lake, a local lake and swamp environment was recorded by peat gyttja sediments. This environment existed until the Ancylus Lake transgression dated ca 10,500 cal BP. During the Ancylus Lake period, the area remained a shallow-water lake, transitional isolated from the main Baltic Basin. The first slightly brackish marine inflows confirmed by the appearance of planktonic, mesohalobous and halophilous diatoms were identified at the beginning of the Initial Littorina Sea stage and dated ca 8800 cal BP. The boundary between the Ancylus Lake and the Initial Littorina Sea is marked by increasing contents of biogenic silica and iron. The Initial Littorina Sea stage was characterized by increasing mesohalobous and polyhalobous diatom forms and decreasing oligohalobous species. The Initial Littorina Sea environment was recorded as a slightly brackish reservoir sporadically affected by weak marine inflows. The Littorina transgression appeared in the Mecklenburg Bay at ca 7500–7700 cal BP and is reflected by the domination of polyhalobous diatoms, increasing mean grain size, biogenic silica, and calcium and magnesium contents. The Initial Littorina Sea was a 1500-year-long period in Mecklenburg Bay, existing until the Littorina transgression. The main Littorina transgression first appeared in Mecklenburg Bay around 7700 cal BP and after a few hundred years at around 7200 cal BP in the Arkona Basin.

“Romoty” is the name of a sediment profile from the overgrown lake located in Elk 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 δ 18 O and δ 13 C 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.

A variety of studies of the re-examined (new exposure) Late Pleistocene key section Cheremoshnik (East European plain, middle of the Volga Basin of Yaroslavl) was conducted on a new methodological level using modern methods. For the first time, a series of paleosols (MIS5–MIS1) from the section offering significant information in regard to chronostratigraphy and landscape evolution have been studied in detail and dated. An excavation ∼7 m deep reveals a soil-sediment stratum which formed over the course of ∼115 ka in an accumulative beam-like terrace and consists of five lithological layers and six pedostratigraphical units. The base of the section was determined to be an Early Mikulino peat-dark humus paleosol which marked incipient subaerial pedogenesis on the Moscow (Riss II) moraine and was covered with a thickness of gyttja with a peat horizon (Histosol) which had formed 114–115 ka and was reliably dated using uranium–thorium dating. The following paleosols were successfully identified within the series of weak stone gullied-channel sediments within the Valdai (Wűrm) thickness (from bottom to top): (1) Bryansk paleosol (MIS3) – Gleysol – with three pedogenesis rhythms; (2) Trubchevskaya paleоsol – Gleyic Turbic Cryosol (MIS2) and (3) pedosediment formed at the end of the Bӧlling interstadial (MIS2). Terminal Pleistocene formations are marked with a gravelly stratum on the section's surface formed during the Preboreal period. Recent Regosol formed on loess-like loam deposits was identified at the top of the whole soil-sediment stratum. The 14C age of the paleosol humus varied between 27,500 and 11,400 cal. BP. The paleosols represent the northernmost occurrence of MIS5–MIS2 fossil soil in Europe, dominated by features of gleyzation, cryogenic aggregation, cracking, and humus and peat formation. Pollen analysis results allowed estimation of changes in vegetation cover, climatic conditions and the age of deposit sedimentation for the period from the Moskow Late Glacial to the Valdai Late Glacial and early Holocene times. Successive stages in the development of vegetation, high contents of alder and hazel pollen and the climax and distinct appearance of broadleaf trees relate the formation of biogenic sediments (LPAZ 2–6) in the Cheremoshnik section to the Mikulino Interglacial. Valdai (MIS4–MIS2) glacial sediment is absent within the investigated area.

This research is focused on a small kettle hole located within the Morąg moraines (Ilawa Lake District, NE Poland). The study objective was to determine the impact of palaeoenvironmental changes in sedimentation and properties of sediments filling the bottom of the kettle hole. Sedimentological, geochemical, and palaeobotanical studies enabled us to distinguish several development phases of the kettle hole, and cluster analysis performed on physicochemical data yielded seven local geochemical zones (Ju I/I to Ju I/VII ). The beginning of biogenic sedimentation in the conditions of a small water body, functioning in the Late Glacial period (4.20–4.10 m), was determined on the basis of palaeobotanical research. Sediments deposited in the lake during its further evolution were rich in microelements such as Ca, Na, Mg, and K, and to a smaller extent – Fe and Mn (Ju I/I–III local geochemical zones). The Late Glacial lacustrine period ended with the accumulation of very silty, pollen-free gyttja, with a stratigraphic hiatus (Ju I/IV , 3.40–3.20 m). The sediments were enriched with SiO2ter, which indicates an increased rate of slope erosion, and concretions of Fe-Mn occurring below this layer (Ju III ) provide evidence for lowering of the water level and even desiccation. In the Holocene, the lacustrine period ended with the accumulation of coarse detrital gyttja (3.20–2.60 m). Palaeobotanical data indicate that the next group of sediments were deposited in the Late Subboreal and Subatlantic periods (2.60–0.0 cm, Ju I/V–VII ; sedge peat). Their properties were varied and related to hydrologic conditions, limited denudation, and vegetation succession. There was also a significant change in the trophic conditions of the water and consequently in the sediments of the kettle hole, which changed during the lacustrine period from basic to acid, and strongly acid in the surface layer. This reaction may be related to a change in the water regime as well as to human impact in the environment, which led to the colonization of the peat bog by Sphagnum moss.

This study aimed to reconstruct environmental changes in the Wkra River Valley near Bielawy Goluskie (central Poland) based on geochemical, palynological and subfossil Cladocera analysis of deposits filling a palaeo-oxbow lake. Two sediment boreholes collected from the palaeochannel bend (BG-1) and neck (BG-2) include full sequences of organic deposits lying on clastic deposits. The lower part of the BG-1 borehole contains gyttja that accumulated during the Younger Dryas and the Preboreal, which is covered by reed peat of Preboreal and Boreal age. On top of this is alder peat that accumulated during the Atlantic. The ages of the gyttja and peat were confirmed by both radiocarbon dating and palynological analysis. The peats are characterized by a significant content of organic matter, which is relatively stable over time. This indicates a low intensity of mechanical denudation in the catchment, which is supported by low concentrations of aluminum and potassium. Calcium values greatly exceed these elements, suggesting that the lake was mainly fed by groundwater. Variation in trophic conditions over time is indicated by a vertical variability in the content of nitrogen, as well as by the Cladocera population. The strong decomposition of peat in the top layer of the mire, and increased concentrations of phosphorus and heavy metals, testify to increasing human activity during the most recent time periods

Spatial distribution of paleolandslides coincides with postglacial faults (PGFs) in northern Fennoscandia, yet the timing of the seismic events and associated paleoslides is insufficiently known. We applied airborne LiDAR (Light Detection And Ranging) to record distribution of paleolandslides possibly associated with the known Suasselka postglacial fault in Kittila, western Finnish Lapland. Landslide-buried organic material was radiocarbon dated to bring insight if the landslides were generated by single high-magnitude ( M w > 7) earthquake or if seismic activity has continued through the Holocene. We found a total of four sets of previously unrecognized paleolandslides to indicate fault-activity in the Kittila area. The size of the landslide scarps exceeded up to 250–300 m in width, up to 600 m in length and 10 m in the height of the back-wall. A previously unrecognized (tentatively PGF) scarp, 6 m in height and in conjunction with paleolandslides, was found in granite rock west of the Kittila village. The slide debris was similar to local tills, yet the maximum electrical conductivity ( σ a ) anisotropy was incoherent to any of the ice-flow (morphological) stages recognized through LiDAR or known fabric-sedimentary stratigraphy. We found peat/gyttja beneath 6 m of slide debris which yielded radiocarbon ( 14 C) age of 4400 ± 35 BP (cal. 5055 yr BP). Our previous finding of landslide-buried woody remnants of birch ( Betula ssp.) yielded cal. 9730 yr BP in Kittila. These ages suggest that seismic activity has continued at least 5 ky after deglaciation.

Multidisciplinary research on the bottom sediments of a kettle-hole at the Retno site (the Brodnica Lake District, north-central Poland) provided some information about changes in hydroclimatic conditions in the Late Glacial and the Holocene. Detailed analysis (sedimentological, palynological, macroremains, geochemical and radiocarbon dating) helped to identify 6 stages in the development of the depression in the village of Gaj (near Retno Lake) with 11 phases of hydroclimatic conditions. Sediments of the Retno profile with a total thickness of 6.72 m reflected individual, natural stages in the development of the depression from a lake to a peat bog. Most of the environmental changes were gradual. A sequence of Late Glacial and early Holocene lacustrine sediments (mainly gyttja) occurred in the floor of the profile. The upper 4.10 m consisted of paludal deposits (peat of transitional and raised bogs) divided at a depth of 1.56–1.54 m b.g.l. by a thin layer of clay dated late Subboreal/early Subatlantic. The presence of this layer indicates a sudden change in the environmental conditions associated with a water level rise. At that time, denudation processes started within the drainage basin, probably induced by human activity. The important effects related to contemporary anthropopressure included desiccation of the peat bog (muck formation in the uppermost 10 cm layer) and elevated trophic conditions resulting in a change of the vegetation cover.

Studies of infills of present-day peatland basins of the Łódź Region revealed the presence of lacustrine sediments underlying peats. They usually rest on mineral bottoms of basins, and their accumulation began in the Late Vistulian and continued in the Holocene. Out of 17 objects subjected to geological and palaeoecological examinations such arrangement was found in 8 of them. In the locality of the Żabieniec peatland 16.4 m of biogenic sediments was documented. The essential part of the profile contains detrital gyttja (at the bottom – detrital-clay gyttja, above – fine detrital gyttja). Within the Ner-Zawada peatland the thickness of biogenic sediments is 4.70 m and lake sediments are represented by clay- calcareous gyttja and calcareous gyttja. The thickness of biogenic sediments in the Ługi peatland reaches to 2.90 m. At this locality detrital- calcareous gyttja and detrital gyttja accumulated on the mineral substratum. In the Rąbień peatland basin the thickness of lacustrine sediments and peat reaches 6.2 m; on sandy bottom rest detrital-clay gyttja and detrital gyttja. In the Silne Błoto-Witów peatland only the 3.5 m long profile of the so- called “west island” contains lacustrine deposits covered by herbaceous peat. In the bottoms of a few other peatlands of the region, biogenic lake deposits were found, but their thickness is small (such as Korzeń, Bęczkowice, Parchliny). Therefore it may be assumed that some peatlands of the Łódź Region are of limnic origin. The presented examples of lake sediment series in the basins of contemporary peatlands in the Łódź Region allow to conclude that during the last fifteen thousand years, lakes occurred in this area, not only in numerous oxbow basins, but also in plateau depressions and aeolian landforms. Lake basins were more frequent during the late Vistulian, and survived in the Holocene until the Subboreal period. All water bodies of wetlands of the Łódź Region, except for oxbows, which are observed today, are of an anthropogenic origin. Analiza wypełnień mis współczesnych torfowisk regionu łódzkiego wykazała pod torfami obecność osadów jeziornych. Zalegają one zwykle na mineralnym dnie mis, a ich akumulacja rozpoczęła się w późnym vistulianie i trwała jeszcze w holocenie. Spośród 17 obiektów poddanych szczegółowym badaniom geologicznym i paleoekologicznym taki układ osadów stwierdzono w ośmiu z nich. W misie torfowiska Żabieniec udokumentowano 16,4 m osadów biogenicznych, a zasadniczą część profilu stanowi gytia detrytusowa (w dolnej części detrytusowo-ilasta, a powyżej gytia drobnodetrytusowa i grubodetrytusowa). W obrębie torfowiska Ner-Zawada miąższość osadów biogenicznych wynosi 4,70 m, a osady jeziorne reprezentują: gytia ilasto-wapienna i gytia wapienna. Miąższość osadów biogenicznych w obrębie torfowiska Ługi sięga 2,90 m, na mineralnym podłożu zalega gytia detry- tusowo-wapienna i gytia detrytusowa. W torfowisku Rąbień miąższość torfu i podścielających go osadów jeziornych sięga 6,2 m, na piaszczystym podłożu zalegają: gytia detrytusowo-ilasta i gytia detrytusowa. Torfowisko Silne Błoto-Witów dokumentuje jedynie profil z tzw. wyspy zachodniej o miąższości 3,5 m prezentujący głównie osady jeziorne, przykryte przez torf zielny. W podłożu torfów kilku innych torfowisk regionu stwierdzono biogeniczne utwory jeziorne, ale ich miąższość jest niewielka (m.in.: Korzeń, Bęczkowice, Parchliny). Uznać więc należy, że część torfowisk regionu łódzkiego ma pochodzenie limnogeniczne. Zaprezentowane przykłady serii osadów jeziornych w misach współczesnych torfowisk regionu łódzkiego pozwalają stwierdzić, że w trakcie ostatnich 15 tysięcy lat jeziora występowały na tym obszarze nie tylko w licznych starorzeczach, ale także w obniżeniach wysoczyznowych i wśród form eolicznych. Zbiorniki jeziorne funkcjonowały liczniej w okresie późnego vistulianu, a w holocenie przetrwały aż do okresu subborealnego. Wszystkie zbiorniki wodne na obszarach mokradeł regionu łódzkiego, poza starorzeczami, obserwowane współcześnie, mają charakter antropogeniczny.

This study presents a detailed analysis of geochemical and biotic proxies in a lake sediment profile to assess the effects of local and regional environmental drivers on the Holocene development of Lake Loitsana, situated in the northern boreal forest of NE Finland. Multi-proxy studies, in particular those that include a detailed plant macrofossil record, from the part of the northern boreal zone of Fennoscandia which has not been affected by treeline fluctuations, are scarce and few of these records date back to the earliest part of the Holocene. A 9-m sediment sequence of gyttja overlying silts representing the last c. 10,700 cal year, allowed for a high-resolution study with emphasis on the early to mid-Holocene lake history. The lacustrine sediments were studied using lithology, loss-on-ignition and C/N ratios, micro- and macro-fossils of aquatic and wetland taxa, diatoms, chironomids and accelerator mass spectrometry 14C dating on terrestrial plant macrofossils. Our study shows that the local development at Loitsana was complex and included a distinct glacial lake phase and subsequent drainage, a history of fluvial input affected by nearby wetland expansion, and lake infilling in an eventual esker-fed shallow lake. Enhanced trophic conditions, due to morphometric eutrophication, are recorded as Glacial Lake Sokli drained and open water conditions became restricted to a relatively small Lake Loitsana depression. pH appears to have been stable throughout the Holocene with a well-buffered lake due to the local carbonatite bedrock (Sokli Carbonatite Massif). The fossil assemblage changes are best explained by a complex mixture of drivers, including water-body conditions (i.e. depth, turbidity and turbulence), rate of sediment input, and the general infilling of the lake, highlighting the need to carefully evaluate the possible influence of such local factors as palaeoenvironmental conditions are reconstructed based on aquatic proxies.

The development of a glacial lake impounded along the retreating, northeastern ice margin of the Fennoscandian Ice Sheet during the last deglaciation and environmental conditions directly following the early Holocene deglaciation have been studied in NE Finland. This so-called Sokli Ice Lake has been reconstructed previously using topographic and geomorphologic evidence. In this paper a multiproxy approach is employed to study a 3-m-thick sediment succession consisting of laminated silts grading into gyttja cored in Lake Loitsana, a remnant of the Sokli Ice Lake. Variations in the sediment and siliceous microfossil records indicate distinct changes in water depth and lake size in the Loitsana basin as the Sokli Ice Lake was drained through various spillways opening up along the retreating ice front. Geochemical data (XRF core-scanning) show changes in the influence of regional catchment geochemistry (Precambrian crystalline rocks) in the glacial lake drainage area versus local catchment geochemistry (Sokli Carbonatite Massif) within the Lake Loitsana drainage area during the lake evolution. Principal component analysis on the geochemical data further suggests that grain-size is an additional factor responsible for the variability of the sediment geochemistry record. The trophic state of the lake changed drastically as a result of morphometric eutrophication once the glacial lake developed into Lake Loitsana. The AMS radiocarbon dating on tree birch seeds found in the glaciolacustrine sediment indicates that Lake Loitsana was deglaciated sometime prior to 10 700 cal. a BP showing that tree Betula was present on the deglaciated land surrounding the glacial lake. Although glacial lakes covered large areas of northern Finland during the last deglaciation, only few glaciolacustrine sediment successions have been studied in any detail. Our study shows the potential of these sediments for multiproxy analysis and contributes to the reconstruction of environmental conditions in NE Finland directly following deglaciation in the early Holocene.

The arrival of Paleoindian peoples in the lower Great Lakes (ca 11.5 ka cal. BP) coincided with a phase of lowstand lakes and rapid environmental change in southern Ontario. At Rice Lake, an archaeologically-rich area north of Lake Ontario, rising Early Holocene water levels inundated wetland areas exploited by Paleoindian and Archaic peoples. In order to better understand the distribution of submerged archaeological sites and the water level history of Rice Lake, a detailed multi-proxy study was conducted on two vibracores extracted from the open lake and a shallow ( The basin stratigraphy consisted of Holocene organic-rich muds (gyttja), laminated marls, and peats overlying glacial Lake Iroquois sands and clay deposits. Two erosional hiatuses indicating lowstand phases (EH-1 ca 12.5–11 ka cal. BP EH-2 ca 6–3 ka cal. BP) were identified by rapid shifts in particle size and thecamoebian abundance and assemblages. The dominant thecamoebian species in the open lake basin were Arcella vulgaris and Centropyxis constricta ‘aerophila’, indicating the trophic status of the lake has remained stable throughout the Holocene. In the McIntyre lagoon, the EH-1 lowstand was associated with a unique bog and wetland species ( Bullinularia and Phryganella sp.) along with the recovery of microdebitage, indicating that Paleoindian peoples were likely exploiting wetland resources such as plants, fish and waterfowl. We show that the study of lacustrine paleoenvironments using a multi-proxy approach provides additional information for identifying areas of archaeological potential and gaining additional understanding of settlement patterns and resource procurement strategies of Paleoindian and Archaic peoples in Southern Ontario.

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.

The basin of Lake Kotokel, located along the eastern shore of Lake Baikal, Russia, has attracted several scientific projects to investigate the climate, vegetation and lake history throughout the Late Pleistocene and Holocene. However, little was known about its basin structure and sediment architecture. Echo sounding and 3.5 kHz single frequency sub-bottom profiling were used to decipher the basin morphology and seismic stratigraphy to a depth of approximately 50 m. The bathymetric map shows a very shallow lake of 4 m mean water depth and an almost flat lake bottom. A distinct elongated small-sized depression of up to 12 m water depth between the north-western coast and a small island developed along an NW-SE-oriented fault line. A total of 46 km of seismic profiles crossing the lake along 12 transects shows that the bottom sediments consist of three different facies, which accords to previously analyzed core sequences. Several distortions of sediment layers at various sites indicate tectonically induced impact, which resulted in up to 3 m vertical offsets of sediment packages at local sites. The offsets indicate a probably still active fault along the western shoreline of the lake. Soft gyttja of the upper 6 m does not show distortions and may have obscured potential younger tectonic activity. The sediments date to the Late Pleistocene. Small updoming features along the boundary between layers I and II may be assigned to degassing processes or to seismic activity. River channel fills along the north-eastern coast are indicative of a lower lake level prior to 15 ka BP. The sediment stratigraphy indicates that suitable coring sites for paleoclimate studies are only located in the southern part of the basin where almost undisturbed sediments can be expected.

This study uses the Holocene lake sediment of Lake Ķūži (Latvia, Vidzeme Heights) for environmental reconstruction with multi-proxy records including lithology, computerised axial tomography scan, grain-size analysis, geochemistry, diatoms and macrofossils, supported by AMS radiocarbon dating. Numerical analyses (PCA; CONISS) reveal three main phases in the development of the lake. Response to the Lateglacial–Holocene transition in Lake Ķūži took place around 11,300 cal. BP. Organogenic sedimentation started with distinctive 5-cm-thick peat layer and was followed by lacustrine sedimentation of carbonaceous gyttja. Several findings of the peat layer with similar dated age and position at different absolute altitudes indicate that lake basin was formed by glaciokarstic processes. In the Early Holocene (until around 8,500 cal. BP), the lake was shallow and holomictic, surrounded by unstable catchment with erosion and inflow events. Predominance of diatom species of Cyclotella and Tabellaria, large numbers of respiratory horns of phantom midge pupae (Chaoboridae), high Fe/Mn ratio, as well as the presence of laminated sediments indicates the transition to a dimictic and oligo-mesotrophic lake conditions with high water level, anoxia in the near-bottom and stable catchment in the Middle Holocene (8,500–2,000 cal. BP). This contrasts with many hydrologically sensitive lakes in Northern and Eastern Europe in which the water level fell several meters during this period. During the Late Holocene (from 2,000 cal. BP to the present), the lithological and biotic variables reveal major changes, such as the increase in erosion (coarser grain-size fraction) and eutrophication [diatoms Aulacoseira ambigua (Grun.) Sim., Stephanodiscus spp., Cyclostephanos dubius (Fricke) Round]. Characteristics of lake-catchment system during the Late Holocene reflect anthropogenic signal superimposed on the natural forcing factors. To date, the Late Quaternary palaeolimnological reconstructions using lake sediment has been limited in the Baltic region. Therefore, findings from Lake Ķūži provide important information about environmental and climatic changes that took place in this part of Eastern Europe. This study shows that the relative importance of climate and local factors has varied over the time and it is essential to consider the lake basin topography, catchment size and land cover as potential dominant forcing factors for changes in sedimentary signal.

Macrofossil analysis and radiocarbon dating were used to determine the age, composition and succession pattern of organic-rich deposits infilling oxbows and flood basins in the Rivers Kłodnica, Odra and Osobłoga valleys (southern Poland). Both detrital sediments representing the aquatic or terrestrial environments as well as five types of peat accumulated in amphibious or peatland conditions have been identified in cores analyzed. Studies have shown that an accumulation of organic-rich deposits was commonly initiated by terrestrialisation and was typically occurred under eutrophic conditions. In such circumstances, deposit sequences usually begin with aquatic detrital sediment (gyttja), or possibly brown-moss or reed peat. These deposits normally pass into sedge-reed peat and then alder peat. If the accumulation of organic-rich deposits was initiated by paludification, alder peat appears in the lowest sections of the fens. In the upper parts of the sequences, apart from wood peat, organic deposits dominated by sedge remains are also present. The latter were accumulated, probably, as an indirect effect of human activities in the floodplains.

The Lateglacial and postglacial sequence in the northern Gulf of Riga is sedimentologically subdivided into nine distinctive layers. In the seismo-acoustic sequence these layers are correlated with seven seismic/acoustic units, which largely reflect different stages in the development of the Baltic Sea. A uniform layer of the Late Weichselian till, a layer of waterlain glacial diamicton (WGD), a varved succession of the Baltic Ice Lake, a brackish-water/freshwater sandy/silty clay of Yoldia Sea, a FeS-rich layer of Ancylus Lake and discordantly bedded sand of the Litorina Sea and present-day gyttja are revealed both in sediment cores and in acoustic recordings. In general, the lateral extent of the distinguished sediment layers is gradually shrinking upwards in the Quaternary sequence towards the deepest, central depression of the gulf. Two distinguished regional discontinuities divide the Lateglacial and postglacial sediment sequence into three allounits: glacial diamicton deposits in the lower part; ice-proximal WGD, glaciolacustrine and postglacial lake/marine deposits in the middle; and brackish-water marine deposits in the uppermost part of the sequence. The presented detailed seismostratigraphic subdivision of the Quaternary sediment sequence of the Gulf of Riga permits a correlation/comparison with similar sequences across the Baltic Sea and in other former glaciated basins.

Paleoenvironmental reconstruction combining data from diatom, pollen, macrophytic, and archaeological analyses had not been attempted previously for coastal Peru. We analyzed two radiocarbon-dated sediment cores extracted from the “sacred” Urpi Kocha Lagoon at the pre-Hispanic religious center of Pachacamac (ca. AD 350–1533), near Lima, to characterize the paleoenvironment of the site. The data reveal an environmental history characterized by alternating periods of severe drought and catastrophic flood. Recurrent pulses with distinctive sediment, diatom, pollen, and macrophytic characteristics reflecting variations in water depth, substrate, turbidity and salinity, usually contain a thick basal sandy storm deposit overlain by thin organic accumulations of peat, gyttja, and snails. The most intense of these disturbance pulses, when correlated with pollen, plant macrofossils, radiocarbon dates, and regional proxy data, provide local evidence of four major floods associated with sustained, catastrophic El Nino events, tsunamis and/or severe storms in the Andean highlands over the last 2000 years.

For decades, detailed studies on Early Weichselian deposits have been made in central Europe. In contrast, these studies are rare in Fennoscandia in northern Europe. We here integrate an extensive multi-proxy data set obtained on sediments of MIS 5d-c age that form part of a long sediment record preserved at Sokli in northern Finland. We make a detailed interpretation of the vegetation and depositional history for MIS 5d-c using pollen, macrofossils, diatoms and other siliceous microfossils, insect remains, and sediment characteristics, and combine these data with recently published estimates on July temperatures based on chironomids and selected plant indicator species in order to make inferences of paleo-climate regimes. The fossil record obtained on the seven meter thick MIS 5d-c deposit at Sokli is exceptionally rich in species due to the large variety of habitats associated with an overall fluvial depositional environment. A braided river system flanked by steppe-tundra vegetation is inferred for MIS 5d. Mean July temperatures of at least 12–14 °C are indicated by chironomids and plant indicator species and are in agreement with the presence of conifers and birch trees as recorded by macrofossils. The reconstructed environmental conditions suggest strong continental climate conditions at Sokli during MIS 5d. The gradual infilling of an oxbow lake and subsequent return to stream channel deposition is traced in great detail in the overlying gyttja and gravelly sediment of MIS 5c age. The terrestrial pollen and plant macrofossil record from the gyttja shows the establishment of birch forest followed by the spread of pine and then spruce. Rich plant indicator species assemblages indicate that the boreal environment at Sokli during MIS 5c experienced July temperatures several degrees higher than the present-day value of 13 °C. The high summer temperatures and presence of larch suggest more continental conditions. More open vegetation returned at Sokli during late MIS 5c and was followed by glaciation by the Fennoscandian Ice Sheet (MIS 5b). Despite the major differences in zonal vegetation types during MIS 5d-c, differences in reconstructed July temperatures are minor and suggest that winter temperatures combined with precipitation values mostly determined the stadial–interstadial climate variability. The most compelling conclusion from our study is that forest development during MIS 5c was remarkably similar to that recorded for the Eemian (MIS 5e) and Holocene Interglacials at the high-latitude site Sokli, and also to that inferred from MIS 5c sediments on the northern European mainland. Our results question the definition of MIS 5c in the terrestrial record of Europe as an interstadial interval of the last glacial cycle and suggest inclusion of MIS 5c together with the Eemian (MIS 5e) in an interglacial complex.

Piston cores from deep-water bottom deposits in Lake Ontario contain shallow-water sediments such as, shell-rich sand and silt, marl, gyttja, and formerly exposed shore deposits including woody detritus, peat, sand and gravel, that are indicative of past periods of significantly lower water levels. These and other water-level indicators such as changes in rates of sedimentation, mollusc shells, pollen, and plant macrofossils were integrated to derive a new water-level history for Lake Ontario basin using an empirical model of isostatic adjustment for the Great Lakes basin to restore dated remnants of former lake levels to their original elevations. The earliest dated low-level feature is the Grimsby-Oakville bar which was constructed in the western end of the lake during a near stillstand at 11–10.4 (12.9–12.3 cal) ka BP when Early Lake Ontario was confluent with the Champlain Sea. Rising Lake Ontario basin outlet sills, a consequence of differential isostatic rebound, severed the connection with Champlain Sea and, in combination with the switch of inflowing Lake Algonquin drainage northward to Ottawa River valley via outlets near North Bay and an early Holocene dry climate with enhanced evaporation, forced Lake Ontario into a basin-wide lowstand between 10.4 and 7.5 (12.3 and 8.3 cal) ka BP. During this time, Lake Ontario operated as a closed basin with no outlets, and sites such as Hamilton Harbour, Bay of Quinte, Henderson Harbor, and a site near Amherst Island existed as small isolated basins above the main lake characterized by shallow-water, lagoonal or marsh deposits and fossils indicative of littoral habitats and newly exposed mudflats. Rising lake levels resulting from increased atmospheric water supply brought Lake Ontario above the outlet sills into an open, overflowing state ending the closed phase of the lake by ~7.5 (8.3 cal) ka BP. Lake levels continued to rise steadily above the Thousand Islands sill through mid-to-late Holocene time culminating at the level of modern Lake Ontario. The early and middle Holocene lake-level changes are supported by temperature and precipitation trends derived from pollen-climate transfer functions applied to Roblin Lake on the north side of Lake Ontario.

Peat and gyttja (organic lake sediment) are important indicators for past environmental conditions; they form in areas where the supply of clastic sediment is insufficient to fill the accommodation space. Previous studies of delta sediments, however, have focused mainly on clastic deposits, whereas organics have received only minimal attention. Identification of organic facies can be of value for understanding delta formation as it provides insight into, for example, palaeoenvironmental conditions and compaction susceptibility of these layers. Currently, however, field characteristics of organics are not well-documented for the full range of facies present in delta plains. In this study, a field method - a classification key - for identifying organic facies in delta plains was developed based on concisely described organic facies in selected cores from the Rhine-Meuse delta, The Netherlands. This method was tested on archived borehole descriptions of the diachronous basal peat layer in the distal Holocene Rhine-Meuse delta; this was done by means of a semi-automated procedure to select and classify samples from a database. The resulting data set was used for mapping organic facies in the basal peat layer by means of indicator kriging and inverse distance weighting. The resulting facies distribution map shows consistent and geologically meaningful patterns, which were interpreted in terms of hydrological regimes. The formation of the basal peat layer, which marks the onset of Holocene aggradation, has been controlled by marine-dominated, fluvial-dominated and seepage-dominated environments. Before 9000cal yr bp, marine processes influenced the initial stage of organic accumulation in the western part of The Netherlands. After 9000cal yr bp, on the flanks of topographical higher regions, seepage-dominated mesotrophic organic facies characterized the onset of accumulation. Simultaneously, nutrient-rich organic facies could develop in the Rhine-Meuse valley: gyttja formed in the sediment-limited Meuse realm, whereas reed peat accumulated in the Rhine realm, indicating lower water depths and thus a higher elevated surface level. It is concluded that the classification key for identifying organic facies is a strong tool to better recognize peat and gyttja types on the basis of macroscopic field characteristics. Application of the key on archived boreholes also proved to be feasible. Identification of organic facies and determination of their spatial distribution at delta scale, as is shown in this study, contributes to understanding delta evolution. © 2011 The Authors. Journal compilation © 2011 International Association of Sedimentologists.

Southernmost Patagonia, located at the relatively narrow passage between Antarctica and South America, is a highly sensitive region for recording meridional and zonal changes in the pattern of oceanic and atmospheric circulation. The island of Isla de los Estados, situated at 54.5°S, 64°W, east of Argentinean Tierra del Fuego, provides an exceptional possibility, to investigate terrestrial records of atmospheric conditions in an oceanic setting during the last deglaciation and the Holocene. Here we present geochemical and diatom analyses from 10 600 to c. 1500 cal BP of one sequence (LGB) with peat, lake sediments and lagoon deposits at the northern coast of the island, and a lake sediment sequence (CAS) 3 km further inland. The data comprise TC, TN, loss on ignition analyses and continuous XRF scanning as well as age–depth modeling based on AMS-14C dating on both cores. Diatom analysis of the CAS record complements the geochemical proxies. During the Holocene, our two sites have been impacted by two different forcings: changes in the regional climate regime largely influenced by the varying strength and position of the Southern Hemisphere Westerlies (SHW), while relative sea-level changes affected the deposits of the coastal site. In concert with the onset of the Antarctic thermal optimum, our data suggest fairly warm conditions and the establishment of denser peat and forest vegetation on the island c. 10 600 cal BP. Between 8500 and 4500 cal BP geochemistry and diatoms from the CAS record indicate stronger Westerlies at this latitude, which means higher wind speed or higher storm frequency and more precipitation, resulting in more pronounced surface run-off. After 4500 cal BP, the geochemical proxies and large changes in diatom assemblages indicate a decrease in precipitation, weaker winds and possibly cooler conditions, probably as an effect of weaker SHW and/or a latitudinal shift. The depositional environment of CAS changed from gyttja to peat around 1000 cal BP. At LGB, the onset of gyttja sedimentation around 7900 cal BP shows that the former wet land with peat accumulation had become a lake with a fairly rapid sedimentation. The chemical data from LGB imply a gradually increasing marine influence, probably as an effect of both rising sea level and increased impact of storms and maximum high tides. After a marine high-stand during the mid-Holocene, the LGB site returned into a peat bog again around 3400 cal BP. Our data suggest that since then relative sea level first dropped back below present sea level followed by a rise to present day sea level. Fil: Unkel, Ingmar . Lund University; Suecia. Kiel University. Institute for Ecosystem Research; Alemania Fil: Fernández, Marilén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentina. Lund University; Suecia Fil: Björck, Svante . Lund University; Suecia Fil: Ljung, Karl. University of Bristol; Reino Unido. Lund University; Suecia Fil: Wohlfarth, Barbara . Stockholms Universitet; Suecia

Low dissolved oxygen during the summer and early fall controls profundal continental ostracode distribution in Crystal Lake (McHenry County), Illinois, favoring Cypria ophthalmica and Physocypria globula at water depths from 6 to 13 m. These species also thrived in the lake’s profundal zone from 14,165 to 9600 calendar year before present (cal yr B.P.) during the late Bolling, Allerod, and Younger Dryas chronozones, and early Holocene. Characterized by sand, cemented tubules, large aquatic gastropod shells, and littoral ostracode valves, thin (1– 6 cm) tempestite deposits punctuate thicker deposits of organic gyttja from 16,080 to 11,900 cal yr B.P. The succeeding 2300 yr (11,900–9600 cal yr B.P.) lack tempestites, and reconstructed water depths were at their maximum. Deposition of marl under relatively well-oxygenated conditions occurred during the remainder of the Holocene until the arrival of Europeans, when the lake returned to a pattern of seasonally low dissolved oxygen. Such conditions are also indicated in the lake sediment by the speciation of phosphorus, high concentrations of organic carbon, and abundant iron and manganese occluded to mineral grains. Initial low dissolved oxygen was probably caused by the delivery of dissolved P and Fe in shallow groundwater, the chemistry of which was influenced by Spodosol pedogenesis under a spruce forest. The triggering may have been regionally warm and wet conditions associated with retreat of the Lake Michigan lobe (south-central Laurentide Ice Sheet).

Binka, K., Nitychoruk, J. & Dzierzek, J. 2010: Climate stability during the Eemian – new pollen evidence from the Nidzica site, northern Poland. Boreas, 10.1111/j.1502-3885.2010.00179.x. ISSN 0300-9483 Interglacial sediments at Nidzica, northern Poland were investigated by means of pollen and isotope analysis. These deposits accumulated in an extensive basin through most of the Eemian and Early Weichselian, practically without stratigraphic gaps. Continuous subsidence of the basin floor has resulted in the accumulation of a great thickness of lacustrine sediments, consisting mostly of calcareous gyttja. The course of pollen and isotope curves in the interglacial interval does not indicate the abrupt climatic shifts reported from some other continental climatic archives. Particularly important has been the reconstruction of the final stages of the Eemian, a potential analogue for future climatic change in the late Holocene. At Nidzica, this period is registered as a gradual modification of forest composition, devoid of any pulsations in which temperate forest is followed by terminal, boreal pine–birch communities.

Engels, S., Helmens, K. F., Valiranta, M., Brooks, S. J. & Birks, H. J. B. 2010: Early Weichselian (MIS 5d and 5c) temperatures and environmental changes in northern Fennoscandia as recorded by chironomids and macroremains at Sokli, northeast Finland. Boreas, Vol. 39, pp. 689–704. 10.1111/j.1502-3885.2010.00163.x. ISSN 0300-9483. A 25-m-long sediment record spanning the time from the Eemian to the Holocene was recovered from Sokli, northeast Finland. This study focuses on a 6-m-long sediment interval that is dated to the Early Weichselian period (MIS 5d and 5c) and consists of lacustrine and fluvial deposits. Using chironomid remains, botanical and zoological macroremains as well as sediment lithology, we were able to reconstruct past changes in the environment, including climate. The results indicate that the site was situated on a flood-plain during the latter stages of MIS 5d (Herning Stadial) and that summer temperatures might have been ∼6 °C lower than at present. Although this value should be treated with caution, as numerical analysis shows that it has a very poor fit-to-temperature, this low reconstructed value concurs with several other reconstructions that are available from western Europe. During MIS 5c (Brorup interstadial), the depositional environment changed into a lake system, initially with stratification of the water and subsequently with complete mixing and a strong influence of streams. Both chironomid-based and macroremain-based temperature inferences indicate past July air temperatures that were significantly higher than at present. This result is in contrast to other (low-resolution) reconstructions from northern Fennoscandia that indicate past temperatures 6–7 °C lower than present using fossil coleopteran assemblages. However, several central European sites indicate that there was a phase during the Brorup interstadial that was characterized by high summer temperatures, and a comparison between the high-resolution reconstructions from western Europe and the results presented in this study suggests that the north–south July air temperature gradient between the mid- and high-latitudes was much weaker during the Brorup interstadial than it is at present. High solar insolation values (particularly the obliquity) during the Brorup interstadial might explain the low summer temperature gradient over the European continent. A return to fluvial conditions occurred in the upper parts of the sediment sequence, and, after a brief interval of gyttja deposition under cooling conditions, the site became glaciated during MIS 5b.

Organic–clastic lake fills, which include lacustrine deltas, are prominent architectural elements in the distal zone of delta plains. We hypothesize that lakes and fossil lake fills affect the development of a fluvial distributary channel. To test this hypothesis, a Holocene palaeogeographic reconstruction is presented of the Angstel–Vecht area, The Netherlands based on a geomorphogenetic map, lithogenetic cross sections, microfossil analyses, and various dating methods (i.e. 14 C-dating, OSL dating, pollen analyses and archaeological evidence). We found that peat accumulation on the Pleistocene substratum started ~ 8000 cal yr BP in response to base-level driven groundwater-level rise. Peat-bounded lakes existed in which gyttja was formed. Fluvial sedimentation in the study area commenced when a new Rhine distributary – the Angstel–Vecht – formed ~ 2970 cal yr BP. As a result, the lakes were filled with fluvially supplied clastic material. Fluvial activity diminished after ~ 2300 cal yr BP although the system continued to function as a high-discharge spillway for Rhine distributaries. This study illustrates the influence of lakes and lake fills on fluvial architecture and sedimentology. Downstream of a lake, levee deposits are thin compared to upstream reaches and the channel-belt sediment is clayey. Furthermore, channels maintain a meandering pattern when organic–clastic lake fills form the substrate because of the relative low bank stability. This is in contrast to straight channels in the distal delta plains that are influenced by erosion-resistant peat substrate.

Lake sediment, glacier extent and tree rings were used to reconstruct Holocene climate changes from Goat Lake at 550 m asl in the Kenai Mountains, south-central Alaska. Radiocarbon-dated sediment cores taken at 55 m water depth show glacial-lacustrine conditions until about 9500 cal. yr BP, followed by organic-rich sedimentation with an overall increasing trend in organic matter and biogenic silica content leading up to the Little Ice Age (LIA). Through most of the Holocene, the northern outlet of the Harding Icefield remained below the drainage divide that currently separates it from Goat Lake. A sharp transition from gyttja to inorganic mud about AD 1660 signifies the reappearance of glacier meltwater into Goat Lake during the LIA, marking the maximum Holocene (postglacial) extent. Meltwater continued to discharge into the lake until about AD 1900. A 207 yr tree-ring series from 25 mountain hemlocks growing in the Goat Lake watershed correlates with other regional tree-ring series that indicate an average summer temperature reduction of about 1°C during the 19th century compared with the early–mid 20th century. Cirque glaciers around Goat Lake reached their maximum LIA extent in the late 19th century. Assuming that glacier equilibrium-line altitudes (ELA) are controlled solely by summer temperature, then the cooling of 1°C combined with the local environmental lapse rate would indicate an ELA lowering of 170 m. In contrast, reconstructed ELAs of 12 cirque glaciers near Goat Lake average only 34 ± 18 m lower during the LIA. The restricted ELA lowering can be explained by a reduction in accumulation-season precipitation caused by a weakening of the Aleutian low-pressure system during the late LIA. Copyright © 2008 John Wiley & Sons, Ltd.

During the Fennoscandian ice recession from the eastern Baltic area, the water level in the Lake Peipsi basin was decreasing and reached a minimum at the end of the Younger Dryas Chronozone. The low lake level episode is represented in the basal deposits by a ca. 0.8 m thick bed of coarse detritus gyttja dated to 9.6–9.1 ka 14C BP. The gyttja lies at an elevation of 20–21 m a.s.l., i.e. about 9 m below the present lake level (30 m a.s.l.), and is buried under a 1.5–2 m bed of fine to medium-grained sand. The overall pollen data indicate a shallow-water littoral environment during the gyttja accumulation in the area studied. The diatom flora in the gyttja is dominated by shallow-water benthic and epiphytic taxa, indicating eutrophic littoral conditions at the time of gyttja accumulation. In the uppermost portion of the gyttja sequence the pollen and diatom successions indicate a short period of land emergence when swampy conditions prevailed in the surroundings.

The basal 150 cm of lacustrine sediment in a 380 cm core from Pine Hill Pond, eastern Newfoundland, includes the late-glacial and early Holocene and contains strong sedirnentological and paleoecological evidence for a climatic oscillation correlative with the Younger Dryas event. Basal late-glacial minerogenic sediments are overlain by a silty gyttja marking the onset of organic sedimentation. An overlying unit comprising 7 cm of silty clay marks a return to mineral sedimentation prior to subsequent uninterrupted deposition of organic sediments. During this phase, the reversion from shrub tundra to a sparser herb-shrub tundra pollen assemblage (Oxyria digyna, Arremisia) is a strong indicator of climatic deterioration at the site. The paleolimnological expression of the Younger Dryas event at this site is manifested by a sharp decrease of diatom concentrations followed by decreases in the relative frequencies of Fragilaria spp., which are largely replaced by a stratigraph-ically restricted group of unusual benthic forms, a rise in the relative frequency of chrysophyte cysts, and a crash in Pediastrum concentrations. The nature and timing of palynological and diatom changes are interpreted in terms of both the direct and indirect consequences of climatic deterioration, as well as within the stratigraphic context of sediment lithological changes.

A 56 cm long core covering ca. 9,000 years was obtained from a small, unnamed lake (78°29.5'N, 4 76°46.8'W) at 295 m elevation, innermost Baird Inlet, Ellesmere Island. The vegetation is high arctic, but locally relatively rich, with areas of Cassiope tetragona–Empetrum–Vaccinium uliginosum heath on the steep slopes above the lake. Cores were taken from the basin centre through ca. 15 m of water. Basal sandy-silt is overlain by 51 cm of laminated silty-gyttja and fine detritus gyttja grading upwards to loose algal gyttja. Three radiocarbon dates indicate rates of sedimentation from 0.07 to 0.04 mm per year. Pollen concentration varies from 1,500 to 2,000 per cm3 in the lower part of the core to 100 to 200 in the upper part; calculated pollen influx is between less than one and 14 grains per cm2 per year. Four local pollen assemblage zones reflect an early pioneer phase (grass-sedge-Oxyria) in the lowermost organic sediment, followed by the appearance and spread of Salix some 8,000 years ago and then, some 7,000 years ago, by a rise in Ericales. A period of vegetational stability with dwarf-shrub heaths follows, lasting for over 3,000 years. The topmost zone shows some increase in indicators of bare ground and fell-field vegetation (Saxifraga, Ranunculus, Papaver, Caryophyllaceae, Dryas) and decline in pollen influx, hence deterioration of local conditions during the last 3,500 to 4,000 years.

A 6.5 m long sediment succession (18.5-2.2 ka BP) from the northern sub-basin of lake Endletvatn was analysed lithologically, palynologically and chemically. The chemical analyses were performed at about 10 cm depth intervals for the following parameters: total organic C, N, P, Fe, Mn, Mg, Na, K, Ca and S, in addition to water content, dry density, and pH. Two main lithostratigraphical units can be distinguished, which also differ substantially in chemical characters. Five chemostratigraphical main units were distinguished. The two lowermost units 1–2 (18.5–12.9 ka BP) correspond to the lower lithostratigraphical main unit and are characterized by minerogenous sediments with low C and N, and high Fe, Mg and K. P is low, partly because of a scarcity of P in parent rocks. Chemostratigraphical unit 3 (12.9-9.6 ka BP) is characterized by increasing C and N and a high N/P ratio (10–20) culminating in the early part of the Younger Dryas, indicating abundant N available for bio-production. The Fe, Mg, and K content is still high, but decreasing, indicating decreasing glacial and kryogenic erosion and allogenic deposition until c. 10.5 ka BP. A hiatus represented by a sand layer covers most of the time-span 10.5–9.6 ka BP. Chemostratigraphical unit 4 (9.6-5.3 ka BP) represents the Holocene thermal optimum in three subunits. In the time interval 9.6–9.1 ka BP, Fe, Mg and K decrease to a minimum and P shows a pronounced increase. The megathermal period c. 8200-5300 BP, is characterized by maxima of C, N and P and a minimum of Fe. The katathermal period after 5.3 ka BP is characterized primarily by increased Fe precipitation, increasing Fe/Mn ratio, and P, C and N at a constantly lower level than during the megathermal. A stable C/N ratio of about 10, of the sediment interval younger than 12.9 ka BP characterizes the sediments as transitional between gyttja and dy. The Holocene lake type varied between weakly oligohumic and mesohumic. Stagnant bottom waters (reducing conditions) occur in the periods 12.9–11.5 ka BP and c. 7.5-5.3 ka BP. The climatic development and other environmental implications of the joint chrono-, chemo-, litho-and biostratigraphical data set are discussed.

Here we present multi-proxy data from two cores taken from Hundred Mile Lake in the Matanuska Valley of south-central Alaska to investigate the climate, vegetation and deglaciation history of the last 14,000 years. The chronology of the cores was controlled by five AMS dates. Sediment lithology changes from clay at ∼14–13 ka (1 ka=1000 cal BP), through marl at 13–8 ka, to gyttja at 8–0 ka. The transition from clay to marl probably represents increased productivity of the lake in a stabilizing watershed, induced by initial Allerod climate warming after ice retreat, as calcite precipitation of marl was facilitated by Chara photosynthesis under high water temperature in summer. The δ18O record obtained from bivalve Pisidium mollusc shells shows several large shifts between 13 and 8 ka. A negative excursion of ∼2‰ in δ18O at 12.4–11.5 ka is suggestive of a regional expression of the Younger Dryas (GS-1) cooling event. A 4.5‰ negative shift from −10.5‰ at 13–11 ka to −15‰ at 10.5–8 ka occurred during the peak carbonate interval around 10.5 ka. This surprisingly large negative shift in δ18O values during the early Holocene thermal maximum has not been documented elsewhere in the region. This shift suggests a major change in atmospheric circulation patterns, possibly through more frequent easterly flow of warm and dry air masses that are also depleted in 18O. Pollen results from marl sediments indicate vegetation change from a herb tundra, through shrub birch-dominated tundra, to an alder forest, which follows closely with other regional pollen sequences in south-central Alaska. The results from this study suggest that the climatic shift during the early Holocene was of greater magnitude than the Younger Dryas event, implying the importance of regional feedback processes in high latitudes in controlling regional climate response to large-scale forcing.

High resolution analyses of a sediment sequence from an in-filled lake on Nightingale Island at 37°S in the South Atlantic have revealed hydrological variations during the last 10 700 cal yr BP, which are linked to shifts in the Southern Hemisphere westerlies and the Meridional Overturning Circulation (MOC) in the Atlantic. The lowermost part of the sequence, 10 700–8600 cal yr BP, consists of peat. The peat is overlaid by gyttja, which continues up to the final overgrowing of the basin around 500 years ago. The transition from peat to gyttja at 8600 cal yr BP implies a significant increase in effective humidity, probably caused by a northward shift of the Southern Hemisphere westerlies after the end of the Antarctic thermal optimum. Recurring phases of increased erosion with high deposition of minerogenic particles, terrestrial organic matter (high C/N ratios), and pollen grains from plant taxa growing in more distal parts of the catchment, indicate periods with higher precipitation. These high precipitation periods correspond to periods of southward shifted Southern Hemisphere Westerlies inferred from South America and with periods of weaker MOC in the North Atlantic. Therefore we conclude that these periods, also characterized by decreased influence from marine aerosols, were not caused by the stronger westerlies, but by weaker MOC and less heat transport from the South to the North Atlantic causing warmer sea surface temperatures (SSTs) and increased precipitation in the South Atlantic. This is the expression of the bipolar seesaw mechanism and implies that it may have been operational also during interglacial conditions.