The Swedish Varve Chronology is an unparalleled tool for linking the deglacial history of Sweden with associated palaeo‐environmental change at an annual time scale, and it forms part of Sweden's cultural heritage. A full deglacial chronology connected to the present day does not yet exist; a notable gap is in southeasternmost Sweden, where few varved records are successfully connected to reconstruct ice‐margin retreat. Deglaciation in southern Sweden covers both the climate transition to the Bølling warm period (~14.7 ka BP) and the ice‐margin transition from a subaqueous to terrestrial terminus. To facilitate investigations into the links between ice‐margin dynamics and abrupt climate change, we revisited the varve chronologies of southern Sweden. We digitized unpublished records, reanalysed existing varve thickness records, and obtained and analysed new varve series both on land and offshore. This combined approach has enabled us to refine and extend the existing south coast chronology east and 78 km northwards. Our new Skåne‐Småland chronology records 725 years of deglaciation, in addition to a younger floating chronology in parts. This chronology suggests that the glacial‐lake terminating Fennoscandian Ice Sheet in southern Sweden initially retreated northwards at ~110–160 m a−1 slowing to 60–70 m a−1 near the palaeo‐shoreline. Between today's mainland and the (now) island of Öland the retreat rates increase three‐ to fivefold. Ice‐margin retreat was initially oriented towards the north (as along the south coast), but later pivoted towards the northwest, signifying a landward retreat of terrestrial ‘Swedish’ ice that became divorced from the Baltic Sea ice‐sheet catchment. Our new 725‐year‐long varve thickness series reveals repeated multidecadal scale episodes of increased sedimentation. These likely signify phases of enhanced ice‐sheet melting that repeat and persist throughout the deglaciation of Skåne‐Småland.

Glacial varves can give significant insights into recession and melting rates of decaying ice sheets. Moreover, varve chronologies can provide an independent means of comparison to other annually resolved climatic archives, which ultimately help to assess the timing and response of an ice sheet to changes across rapid climate transitions. Here we report a composite 1257‐year‐long varve chronology from southeastern Sweden spanning the regional late Allerød–late Younger Dryas pollen zone. The chronology was correlated to the Greenland Ice‐Core Chronology 2005 using the time‐synchronous Vedde Ash volcanic marker, which can be found in both successions. For the first time, this enables secure placement of the Lateglacial Swedish varve chronology in absolute time. Geochemical analysis from new varve successions indicate a marked change in sedimentation regime accompanied by an interruption of ice‐rafted debris deposition synchronous with the onset of Greenland Stadial 1 ( GS ‐1; 12 846 years before AD 1950). With the support of a simple ice‐flow/calving model, we suggest that slowdown of sediment transfer can be explained by ice‐sheet margin stabilization/advance in response to a significant drop of the Baltic Ice Lake level. A reassessment of chronological evidence from central‐western and southern Sweden further supports the hypothesis of synchronicity between the first (penultimate) catastrophic drainage of the Baltic Ice Lake and the start of GS ‐1 in Greenland ice‐cores. Our results may therefore provide the first chronologically robust evidence linking continental meltwater forcing to rapid atmosphere–ocean circulation changes in the North Atlantic.

The long warming transition from the Last Ice Age into the present Interglacial period, the last deglaciation, holds the key to our understanding of future abrupt climate change. In the last decades, a great effort has been put into deciphering the linkage between freshwater fluxes from melting ice sheets and rapid shifts in global ocean-atmospheric circulation that characterized this puzzling climate period. In particular, the regional expressions of climate change in response to freshwater forcing are still largely unresolved.This projects aims at evaluating the environmental, hydro-climatic and oceanographic response in the Eastern North Atlantic domain to freshwater fluxes from the Scandinavian Ice Sheet during the last deglaciation (~19,000-11,000 years ago). The results presented in this thesis involve an overview of the regional representations of climate change across rapid climatic transitions and provide the groundwork to better understand spatial and temporal propagations of past atmospheric and ocean perturbations.Specifically, this thesis comprises i) a comparison of pollenstratigraphic records from densely 14C dated lake sediment sequences, which provides insight into the regional sensitivity of North European vegetation to freshwater forcing in the Nordic Seas around the onset of the Younger Dryas stadial (~12,900 years ago); ii) a reconstruction of North European hydro-climate, which, together with transient climate simulations, shed light on the mechanisms and regionality of climate shortly prior to the transition into the Younger Dryas stadial; iii) studies of a ~1250-year long glacial varve chronology, which provides an accurate timing for the sudden drainage of proglacial freshwater stored in the former ice-dammed Baltic Ice Lake into the North Atlantic Ocean; iv) a 5000-year long terrestrial-marine reconstruction of Eastern North Atlantic hydro-climate and oceanographic changes that clarifies the hitherto elusive relationship between freshwater forcing and the transient behaviour of the North Atlantic overturning circulation system. The results presented in this thesis provide new important temporal constraints on the events that punctuated the last deglaciation in Northern Europe, and give a clearer understanding of the ocean – atmosphere – ice-sheet feedbacks that were at work in the North Atlantic. This increases our understanding of how the Earth climate system functions in more extreme situations.

ABSTRACTHere we present a 710‐year‐long floating varve record from south‐east Sweden. Tephra analyses confirm the presence of the rhyolitic Vedde Ash preserved within two consecutive varve years, confirming the Younger Dryas age of the varve series. This permits, for the first time, direct correlation of Swedish varved clay with other records of equivalent resolution which also preserve the Vedde Ash and demonstrates that the potential exists to independently date the Swedish Timescale. This discovery will allow direct comparison of rates, timing and duration of key climatic events across Europe and the North Atlantic region in records of equivalent resolution.

A sediment core from Lake Pichozero (6146'; N, 3725'; E 118 m a.s.l.) provides information on the environmental and climatic conditions in southeastern Russian Karelia during the Lateglacial and early Holocene (12 800-9300 cal. BP). The chronology of the sequence is constrainied by varve counting and AMS 14C measurement of terrestrial plant macrofossils. Multiproxy analyses (magnetic susceptibility, grain size, TOC, TN, TS, Rock Eval, pollen and macrofossils) imply that cold and dry regional climatic conditions with sparse Arctic vegetation prevailed prior to 11500 cal. BP. Coincident with the transition to the Holocene at 11 500 cal. BP, air temperatures and lake productivity increased and Betula pubescens and Populus treinula started to migrate into the area, followed by Picea abies at 10 750 cal. BP. Although lake productivity decreased at around 11 000 cal. BP and remained low until 9600 cal. BP, pollen-based climate reconstructions imply variable climatic conditions in the region over time. Drier and colder summers prevailed from 11 200 to 10900 cal. BP, followed by an interval of higher annual temperatures and precipitation from 10900 to 10750 cal. BP. Lower annual temperatures and drier conditions existed from 10750 to 10200 cal. BP, and higher temperatures and precipitation are inferred between 10200 and 10000 cal. BP. Finally, declining temperatures and precipitation occurred from 10 000 cal. BP onwards, with a minimum at around 9600 cal. BP. These climatic shifts are temporally coincident with those recorded in North Atlantic terrestrial, marine and ice-core archives and indicate that relatively minor climate signals were transmitted further to the east.

High-resolution lithostratigraphy, mineral magnetic, carbon, pollen, and macrofossil analyses, and accelerator mass spectrometry 14C measurements were performed in the study of a sediment sequence from Lake Tambichozero, southeastern Russian Karelia, to reconstruct late-glacial and early Holocene aquatic and terrestrial environmental changes. The lake formed ca. 14,000 cal yr B.P. and the area around the lake was subsequently colonized by arctic plants, forming patches of pioneer communities surrounded by areas of exposed soil. A minor rise in lake productivity and the immigration of Betula pubescens occurred ca. 11,500 cal yr B.P. The rise in summer temperatures probably led to increased melting of remnant ice and enhanced erosion. The distinct increase in lake productivity and the development of open Betula-Populus forests, which are reconstructed based on plant macrofossil remains, indicate stable soils from 10,600 cal yr B.P. onward. Pinus and Picea probably became established ca. 9900 cal yr B.P.

The laminated sediments at Pudozh in eastern Karelia are generally assumed to have been deposited between 13 000 and 16 000 14C yr BP and have been used to date the recession of the active ice margin. However, 17 AMS 14C measurements performed on terrestrial plant macrofossils contained in these sediments show that deposition began during the late Allerφd, when the ice margin had already receded to the northern part of Lake Onega. Based on an age model, we assume that the 1933‐year‐long varved sequence covers the time period between c. 12 900 and 11 000 calendar years BP. During this period, which comprises the later part of the Late Weichselian and the early Holocene, the local vegetation consisted of open, tree‐less dwarf shrub heaths. Increased soil erosion may have occurred before 12 550 calendar years BP.

The Ekeby site, south of Stockholm, has been chosen to elucidate glaciofluvial sedimentation processes soon after the end of the Younger Dryas. Detailed lithofacies and grain-size analyses of gravel, sand and fine sediment sequences in a gravel pit reflect changes in the depositional environment. Four main facies assemblages have been distinguished. The lowermost part of the sequence was probably deposited in a subglacial conduit environment. The middle part of the sequence reflects a transition to a proglacial subaqueous environment. The upper part of the latter sequence probably occurred during increased melting of the ice. The sequence was then covered by beach gravel formed during the regression after the drainage of the Baltic Ice Lake.

The transition from Late Palaeolithic to early Mesolithic cultures is strongly associated with the major environmental and climatic changes occurring with the shift from the Younger Dryas to the Holocene in northern Europe. In this paper, we present an interdisciplinary study combining archaeological and palaeoenvironmental research in an attempt to examine the relationship between environment and culture during this transition. Lundby Mose is a former kettle hole lake in southern Denmark where the earliest Danish human traces of the Holocene were excavated. Two types of bone deposits were found, 1) ritual offerings of worked, marrow-split elk bones and antler and 2) settlement waste with multiple species. These date to the early Holocene and are affiliated to the early Maglemose culture. The modelled 14C ages suggest that the bones were deposited in four phases. A pollen based palaeoenvironmental reconstruction suggests that the ritual offerings were deposited in an environment of limited, underdeveloped forest with unstable soils and areas of open grassland. The settlement waste deposit is associated with a more developed Preboreal forest type. This forest type was not fully established until c. 11,250 cal BP and if substantiated by further evidence, may be one of the reasons why there are no known early Maglemose/Preboreal settlement sites in southern Scandinavia.

Ever since the first clay-varve correlation was carried out by Gerard De Geer in 1884, a large quantity of clay-varve data has been collected in Sweden. Some of this material is stored at the Geochronological Institute of the Department of Quaternary Research, Stockholm University, while some is stored in individual research records. A large proportion of this clay-varve material forms the basis of the Swedish Time Scale which is more than 13,000 years long and covers both the deglaciation of Sweden and the postglacial time. In order to make this unique material available to the scientific community the data are now being compiled and transformed into digital form in a database. Clay-varve material can be stored in, at least, three different ways. The older, historical, material is, in many cases, available only as varve graphs, some of it is kept in numerical form and a limited part has been transformed into digital form. Material which is stored only as varve diagrams must, in one way or another, be transferred to the digital format. The database is a GIS related base using the GIS-program QUIKMap. By creating a database of this type it is possible to make a search for sites with clay-varves covering a specific time span but it is just as easy to search for all clay-varve sites within a restricted geographical area.

The increasing focus on the chronology of environmental and climatic changes of the last glacial‐interglacial transition has led to several independent attempts to try to calibrate the 14C time‐scale beyond the Holocene. The Late Weichselian Gotiglacial varved clays of the Swedish Time Scale could potentially be used for this purpose. The reliability of the Swedish Time Scale is discussed as well as different ways of using the Swedish varved clays for calibrating the 14C chronology. The strategy and initial results from an ongoing calibration project are presented. They show clearly that, if the right strategy is adopted, varved clay may be dated by accelerator mass spectrometry (AMS) 14C measurement of terrestrial macrofossils. A Late Weichselian ‘event stratigraphy’, including the Vedde Ash fall‐out, is established for south Scandinavia using three dating categories: clay varve measurements, terrestrial macrofossil measurement, and lake sediment (including aquatic mosses) measurements. It suggests that a 14C chronology based on terrestrial organic remains is not consistent with the traditional Late Weichselian chronostratigraphy based on lake‐sediment samples, and that ‘clay varve years’ exceed ‘terrestrial 14C years’ by c. 900 years at the end of, and by 1100–1200 years at the beginning of the Younger Dryas Chronozone. Further back in time, the time‐scales appear to converge. These results are compared with other recently published calibration studies.

While working with the revision of the Swedish Time Scale, based on clay-varve chronology, mollusc shells of Portlandia (Yoldia) arctica were found in the clay at Ekensberg, Stockholm, Sweden, deposited at the beginning of the Finiglacial epoch. The clay-varves have been connected with the revised Swedish Time Scale and the time for deposition is 10,370 clay-varve years cal BP. Shells of bivalves, shell fragments and periostracum have been AMS radiocarbon-dated at the The Svedberg Laboratory in Uppsala. The 11 radiometric datings are grouped in two assemblages, one between 10,500 and 11,600 BP (shell carbonate) and one between 8200 and 9100 BP (periostracum). These results are compared with the radiocarbon age obtained for a fish skeleton (Salmo alpinus) found in varved clay close to Ekensberg during the geological mapping of the area. The age of the fish is 8600 BP. which is in agreement with the periostracum datings. Reservoir effects and calibration of the radiocarbon ages (BP) to sidereal years (cal BP) are discussed.

BoreasVolume 21, Issue 4 p. 372-372 Free Access Strange results give rise to strange discussions Lars Brunnberg, Lars Brunnberg Department of Quaternary Research, Stockholm University. Odengatan 63. S-113 22 Stockholm, Sweden: Goran Passnert. The Scedberg Laboratory, University of Uppsala, Box 533, S-751 21 Uppsala. SwedenSearch for more papers by this author Lars Brunnberg, Lars Brunnberg Department of Quaternary Research, Stockholm University. Odengatan 63. S-113 22 Stockholm, Sweden: Goran Passnert. The Scedberg Laboratory, University of Uppsala, Box 533, S-751 21 Uppsala. SwedenSearch for more papers by this author First published: December 1992 https://doi.org/10.1111/j.1502-3885.1992.tb00041.xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume21, Issue4December 1992Pages 372-372 RelatedInformation

Detailed mapping of the clay-varve sediments and stratigraphical analysis of isolated lake basins on the Södertörn peninsula have been undertaken as part of the research project “Eastern Svealand: Development of the Holocene Landscape”. The varve studies have identified three distinctive stratigraphical units and indicate that deglaciation took place between 11,400 and 10,400 clay-varve years BP. Initially recession of the ice margin was slow but subsequently it became more rapid. Study of 15 isolation basins has allowed a tentative shore displacement curve to be constructed for the area. This curve is marked by varied rates of regression and possibly displays 3 Litorina transgressions. The curve suggests markedly different ages for the transgression events than those proposed by earlier authors and this is assessed in terms of curve construction and dating errors. Archaeological evidence indicates that coastal settlements changed their altitudinal location in response to changes in sea level, this evidence supporting the data derived from isolation basins.

Two varved clay sequences, at Rystad and Tottnäs, situated in the Middle Swedish ice marginal zone were analysed palaeomagnetically. Two parallel profiles were sampled and analysed at each site. The varved clay at Rystad was dated by floating varve chronology. The varves at Tottnäs can be linked to Swedish time scale, expressed in calendar years B.P. Due to the distance between the sites they cannot be correlated by means of varve diagrams. Palaemagnetic methods were used as an alternative. Based an AF demanetization of pilot samples, the palaeomanetic to be too low, in the order of15d̀, compared to the site latitude. At Tottnäs the inclination records are very close to the expected inclination with respect to the site latitude. Because of a systematic inclination error in the Rystad profiles the correlation was based on the declination records. Statistical comparisons of these records between the two sites indicate that the sediment successions are partly synchronous. It is concluded that the deglaciation at Tottnäs started c. 130 years earlier than at Rystad. This mean that the Swedish ice marginal zone east of Rystad will have a more northeasterly extension than previously thought.