bluuebunny/crossref_metadata_2025 huggingface dataset:
Glacial history and marine environmental change during the last interglacial‐glacial cycle, western Spitsbergen, Svalbard
Authors: MILLER GIFFORD H. , SEJRUP HANS PETTER , LEHMAN SCOTT J. , FORMAN STEVEN L.
Published: July 2010

Superimposed glacial and marine sediment exposed in coastal cliffs on Brøggerhalvøya, west Spitsbergen, contain four emergence cycles (episodes D, C, B, and A) that are related to glacial‐isostatic depression and subsequent recovery of the crust. Tills are found in episodes C and B; in each case glaciation began with an advance of local glaciers, followed by regional glaciation. The marine transgression following episode C deglaciation reached 70 to 80 m above sea level. Glacial‐marine and sublittoral sands within episode C contain a diverse and abundant microfauna requiring marine conditions more favorable than during the Holocene. We define this interval as the Leinstranda Interglacial. Based on the fauna, sedimentology and geochronology (radiocarbon, amino acid racemization, and uranium‐series disequilibrium) we conclude that the Leinstranda Interglacial occurred during isotope substage 5e. Episode B deglaciation occurred late in isotope stage 5 (c. 70 ± 10 ka ago), and was followed by a marine transgression to about 50 m above sea level. The associated foraminifera, mollusca, and vertebrate fauna require seasonally ice‐free conditions similar to those of the Holocene, but less ameliorated than during the Leinstranda Interglacial. A significant influx of Atlantic water into the Norwegian Sea, augmented by a local insolation maximum late in isotope stage 5, are required to produce shallow‐water conditions similar to those of the Holocene. There is no evidence for major glacial activity during the Middle Weichselian (isotope stages 4 and 3), and we conclude that ice margins were not significantly different from those of the late Weichselian, but the record for this interval is scant. The extent of ice at the Late Weichselian maximum was less than during either of the two preceding episodes (B or C). Late Weichselian deglaciation (episode A) began prior to 13 ka B.P. Oceanic and atmospheric circulation patterns conducive to large‐scale glaciation of western Spitsbergen are not well understood, but those patterns that prevailed during isotope stages 4,3, 2, and 1 did not produce a major glacial advance along this coast.
Holocene moraine and paleosol stratigraphy, Bugaboo Glacier, British Columbia
Authors: OSBORN GERALD , KARLSTROM ERIC T.
Published: July 2010

Sequences of tills, buried paleosols, wood and tephra in lateral moraines provide a record of Holocene advances and retreats of the Bugaboo Glacier in British Columbia. The oldest paleosol is tentatively classified as a Spodosol (Cryorthod). It incorporates Mazama tephra (6,800 B.P.) and charcoal and humus dated at 3,390 and 4.400B.P., respectively, and records early and middle Holocene warming and/or drying. This paleosol overliesa latest Pleistocene or early Holocene till associated with a nearby end moraine and assigned to the regionally known ‘Crowfoot Advance’. Less‐developed paleosols (Cryumbrepts) are formed on Neoglacial tills deposited shortly before 3,000 B. P., between c. 2,500 to 1,900 B. P., and between c. 900 B.P. and the 19th century. The paleosols and surface soils form microcatenas with morphological variations due to differences in original topography and vegetation. The chronology derived from these paleosols and tills generally agrees with, but increases the resolution of, what is known of Holocene glacier histories in the Canadian Cordillera.
Quaternary zoogeography of the Nearctic Dicrostonyx lemmings
Authors: MEAD EMILEE M. , MEAD JIM I.
Published: July 2010

Twenty‐four fossil localities of Dicrostonyx lemmings are reported in North America. The fossil localities are all extralimital except two, one in Alaska and one in the Northwest Territories. The Pleistocene fossil distribution parallels the modern ranges: Dicrostonyx hudsonius east of Hudson Bay and the Appalachian Mountains and D. torquatus to the west. Dicrostonyx remains of the late Quaternary are generally found in disharmonious faunas and may therefore not be an accurate indicator of a strict tundra environment.
Late Pleistocene foraminiferal stratigraphy on the Vøring Plateau, Norwegian Sea
Authors: HAAKE FRIEDRICH‐WILHELM , PFLAUMANN UWE
Published: July 2010

Quantitative studies of foraminiferal faunas and isotope ratios have been done in two gravity cores from the Vøring Plateau. Core 23199 from about 2000 m water depth included sediments younger than oxygen Stage 7. Core 23205 from about 1400 m ended in sediments from Stage 5. According to the transfer temperatures, the onset of abundances of Cibicidoides wuellerstorfi and the δ13C values of Neogloboquadrinapachyderma, the Vøring Plateau was covered by pack‐ice during Stages 6,4,2 and, to some extent, also during Stage 3. Ice‐free sea‐surface conditions prevailed from late Substage 5e throughout Stage 5 and during stage 1. The transition from Stage 6 to Stage 5 (Termination II) took place in two steps: Ila is defined by the δ18O signal of N. pachyderma (reduced global ice volume) and lib by the increased occurrence of C. wuellerstorfi (melting of local pack‐ice). A contemporaneous development of an interglacial deep‐water circulation system is indicated.
Occurrence of larch (Larix) in Fennoscandia during the Eemian interglacial and the Brørup interstadial according to pollen analytical data
Authors: FORSSTRÖM LARS
Published: July 2010

The occurrence of pollen and macrofossils of larch in Eemian deposits in northern Finland indicates that this species must have grown in the area during the last interglacial. Lark spread to Finland from the east, its date of arrival being deducible from the general vegetational succession. It probably did not grow in central or southern Finland during the interglacial, but is thought to have extended fairly far south in Sweden and Noway along the Fennoscandian mountain range. The Lark pollen found at the upper boundary of the interglacial deposits at Margreteberg and Stenberget in southern Sweden may suggest that it did reach southern Sweden by the very end of the Eemian, but it cannot be said for certain whethcr this pollen represents an influx of Larix from the north or from Central Europe.
Late Pleistocene‐Holocene planktic foraminifera of the western equatorial Pacific
Authors: BOLTOVSKOY ESTEBAN
Published: July 2010

Planktic foraminiferal assemblages were studied qualitatively and quantitatively in 13 samples obtained at 3 cm intervals throughout the uppermost Pleistocene‐Holocene deposits of Box core 123 (Eurydice Expedition, western equatorial Pacific Ocean). Absolute ages of these samples have previously been determined by the 14C method; the lowest sample dated from approximately 16,000 B.P. A curve based on the ratio between specimens of warm and warm‐temperate vs. cold and cold‐temperate water assemblages suggests that two temperature drops occurred during this time‐span: at 11,OOO B.P. and around 4,000–2,OOO B.P. The former drop corresponds to the onset of the Younger Dryas cooling. An unexpectedly high dominance of Globigerinita clarkei (up to 60%, on the average 48.5%) was observed throughout the entire core. Isolated, small‐sized and poorly developed specimens of typical cold water foraminifera were present in the materials investigated; their origin is most probably due to advection via equatorward subsurface currents.
Till stratigraphy and ice movements in eastern Overijssel, The Netherlands
Authors: KLUIVING SJOERD J. , RAPPOL MARTIN , WATEREN DICK VAN DER
Published: July 2010

A three–till section in eastern Overijssel, eastern Netherlands, represents the most complete till sequence of the Older Saalian glaciation presently known from The Netherlands and adjacent Germany. On the basis of structural analyses, four different glacial events within one continuous glacial cover can be distinguished: (1) deposition of till 1 (lowest till) by ice probably moving in a southerly direction, (2) glaciotectonic dislocation of till 1 under a compressive strain regime acting towards the west, (3) deposition of till 2 by ice moving in a westerly direction, and (4) deposition of till 3 by southeasterly moving ice. During deposition of tills 2 and 3, the underlying older tills were subjected to a strong extensional tectonic regimc, leading among other things to the development of characteristic sheath folds. On the basis of directional and compositional characteristics, the three tills can be correlated with the till stratigraphy of the northern Netherlands.
Glacially crushed quartz grains in loess as indicators of long‐distance transport from major European ice centers during the Pleistocene
Authors: MAHANEY WILLIAM C. , ANDRES WOLFGANG
Published: July 2010

Detailed mineralogical analysis of the fine and very fine sand fractions (63–250) in the Dreihausen Loess Sequence shows the presence of numerous glacially crushed grains, including a significant amout of quartz. Previous theories regarding the origin of loesses in central Germany held that all sediments were derived locally, following short‐distance transport from nearby sandstone outcrops. New data presented here show that many quartz and feldspar grains were glacially crushed, weathered, crushed again, transported, and emplaced by aeolian processes at Dreihausen. Crushing features observed are compatible with transport in both continental and alpine glaciers; some clasts show the effects of abrasion by both water and ice transport, while others are partly rounded presumably by fluvial and/or aeolian processes. Stronger palewind systems during the Pleistocene presumably contributed to the transport and emplacement of glacial grains from ice centers in both the Alps and the Baltic areas, and also possibly from the Rhine Basin.
The age and origin of Neoglacial moraines in Jotunheimen, southern Norway: new evidence from weathering‐based data
Authors: McCARROLL DANNY
Published: July 2010

This paper considers the controversial issue of the existence of pre‐‘Little Ice Age’ Neoglacial moraines in southern Norway. Schmidt hammer rebound values are combined with measures of boulder roundness and weathering rind thickness in an attempt to isolate moraines that include weathered boulders. A critical approach is used in distinguishing sites where boulders have weathered in situ from those where previously weathered clasts have been incorporated into relatively young moraines. The results confirm that possible pre‐‘Little Ice Age’ Neoglacial moraines seem to be restricted to small, high‐altitude glaciers in eastern Jotunheimen. It is concluded that at these glaciers a particularly large response to a short‐lived earlier Holocene climatic event is more likely to explain the survival of such moraines than a particularly subdued response to the climatic deterioration of the ‘Little Ice Age’. More refined dating techniques are required to determine the age of formation of the anomalous moraines, but before the palaeoclimatic significance of such dates can be assessed, a critical test is required to establish whether the moraines mark former ice‐front positions, and therefore reflect lowering of equilibrium line altitudes, or whether they have been displaced forwards by later and more extensive glacier advances.
Magnetic measurements recording Late Holocene man‐induced erosion in S. Greenland
Authors: SANDGREN PER , FREDSKILD BENT
Published: July 2010

Magnetic measurements have been carried out on four lake sediment successions in interior S. Greenland. The longest record extends back to 7000 C14 years BP. Based on the magnetic susceptibility six units have been distinguished. The results of the magnetic analyses show a close correlation between the four investigated sites, corroborated by pollen stratigraphy and radiocarbon dates. The period after the deglaciation, lasting for some thousand years, was characterized by sparse vegetation on the unstable soils. Erosion rates were high as revealed by the high concentration of magnetic minerals. Along with the spreading of dwarf‐shrub heaths the soils stabilized, reducing the eroding capacity, and are seen as decreasing concentrations of magnetic minerals in the sediments. During the subsequent period there seems to have been an equilibrium between climate and vegetation resulting in minimal erosion. The arrival of the Norsemen in c. AD 1000, introducing cattle and cutting down the ‘forests’, seems to have caused a disturbance in the fragile environment. It destroyed the attained equilibrium and is seen in the sediment records as an increase in magnetic concentrations. Due to the disappearance of the Norsemen in the 15th century, or slightly later, a new phase of soil stabilization began. A new and still ongoing phase of even more severe soil erosion is connected with the reappearance of man, now as a sheep breeder, in the beginning of this century. Magnetic concentrations are again high, being in the same order of magnitude as during early Holocene time.
Do the anomalous fluctuations of Sólheimajökull reflect ice‐divide migration?
Authors: DUGMORE ANDREW J. , SUGDEN DAVID E.
Published: July 2010

Ice‐divide migration may explain the pattern of Holocene glacier fluctuations around the Mýrdalsjökull ice cap in southern Iceland. On at least three occasions Sölheimajokull, the principal outlet glacier on the southwest flank of the ice cap, has exceeded the Little Ice Age limits of recent centuries that mark the maximum extent of neighbouring glaciers in the Holocene. Bedrock divides beneath the Mýrdalsjökull ice cap do not coincide with present ice divides. It is suggested that the ice divide migrated during the course of ice‐cap growth. At various stages during the Holocene (7000‐4500, c. 3100, 1400‐1200 BP) Sólheimajokull could have drained more of the ice cap than today, so becoming more advanced than neighbouring glaciers. In the Little Ice Age (c. AD 1600–1900) the glacier could have had a smaller catchment as a result of ice‐divide migration, resulting in a more inhibited advance compared with neighbouring glaciers which reached their Holocene maximum at that time. Identification of ice‐divide migration is important for palaeoclimatic reconstructions because of the need to recognize different responses of glaciers to climate if one is to use their fluctuations as indicators of change.
Allerød‐ Younger Dryas sea level changes in southwestern Sweden and their relation to the Baltic Ice Lake development
Authors: BJÖRCK SVANTE , DIGERFELDT GUNNAR
Published: July 2010

Mt. Kroppefjall is situated just south of the Middle Swedish (Younger Dryas) ice‐marginal zone. Its abundance of lake basins makes it very suitable for detailed shore displacement studies close to the Younger Dryas ice margin. Altogether 12 lakes at altitudes between 157 and 78 m were studied and all but one situated above the marine limit contained marine sediments. The dating of their isolation from the sea resulted in a shore displacement curve from c. 11,200 to c. 98M)BP. The relative uplift almost ceased between 10,900 and 10,300 BP, which is mainly related to an ice readvance in the Lake Vanern basin. This period of balance between uplift and sea level rise was preceded by a relative uplift rate of 5 m/lW yr and followed by as high rates as 7–8 m/100 yr, possibly caused by a delayed uplift effect and perhaps also a local fall in sea level caused by the rapidly receding ice margin. The time difference between the formation of two delta surfaces at Odskolts Moar is estimated at 60&800 years. Shoreline diagrams along the Swedish west and east coasts, mainly based on a number of shore displacement curves, reveal large anomalies that are believed to have been caused by dammings and drainages of the Baltic basin. The southwards extrapolated shorelines indicate that the bedrock threshold in the Oresund Strait, between Denmark and Sweden, functioned as the outlet threshold for the Baltic Ice Lake during its dammed stages, while the erosion of the Store Balt and Darss Sill straits began at the culmination of the Ancylus transgression and continued during the rapid IS20 m Ancylus regression.
Glaciotectonic effects on a Middle‐Wisconsin boreal fenland peat in Michigan, USA
Authors: RIECK RICHARD L. , KLASNER JOHNS S. , WINTERS HAROLD A. , MARLETTE PERRY A.
Published: July 2010

A variety of glaciotectonic structueres are associated with a distinctive Middle‐ Wisconsin organic formation that is exposed at thirteen places along Michigan's Pine River. The carbonaceous material, with a 14C age of about 46,000 years BP, accumulated in an extensive, weakly geogenous, oligotrophic fen that was buried by sand before being deformed. Numerous faults and folds, the latter with observed amplitudes that may exceed 5 m, have a consistent sense of easterly structural vergence indicating glacial movement from the west. Gelogic relationships here and generally accepted regional chronology indicate that deformation was produced by Late Wisconsin ice that flowed from the Lake Michigan basin. This unequivocal marker bed provides detailed information on the topography, environment, and climate associated with an ice‐free Middle‐wisconsin landscape. Equally important and unprecedented for the area, it is an especially precise measure of multiple glaciotectonic effects upon an incompetent Pleistocene organic formation of considerable extent.
Saalian sediments of the Belchatów outcrop, central Poland
Authors: KRZYSZKOWSKI DARIUSZ
Published: July 2010

The deposits of six glacial episodes, including five till beds and fluvial deposits of one temperate substage, stratigraphically lying between the Holsteinian and Eemian Interglacials have been recognized in the geological record of the Kleszczów Graben, central Poland. Two other temperate substages have been recognized on the basis of well‐developed weathering horizons on the tills. The depositional environments and general petrological features of these sediments are described and their stratigraphical position is discussed. The Saalian Complex of the Kleszczów Graben has been subdivided into the Older Saalian (three glacial episodes), the Pilica Interstadial and the Younger Saalian (three glacial episodes and two presumed interstadials). This sequence cannot be simply correlated with other Saalian stratigraphic sequences in Europe, although the pre‐Odranian and Odranian (=main Drenthe) tills most probably belong to the Older Saalian, and the Wartanian (Warthe) tills to the Younger Saalian. The geological record presented here suggests that reforestation phases occurred during the Saalian. This contradicts recently developed continental stratigraphics.
Late Pleistocene equilibrium‐line reconstructions in the northern Peruvian Andes
Authors: RODBELL DONALD T.
Published: July 2010

Equilibrium‐line‐altitude (ELA) reconstructions using the toe‐to‐headwall‐altitude ratio method for paleoglaciers in the Cordilleras Blanca and Oriental, northern Peruvian Andes (7–10°S; 77°20′–77°35'W), indicate that ELAs during the last glacial maximum (LGM; marine isotope stage 2) were c. 4300 m in the Cordillera Blanca, c. 3900–3600 m on the west side of the Cordillera Oriental, and c. 3200 m on the east (Amazon Basin) side of the Cordillera Oriental. Comparison with estimated modern ELAs and glaciation thresholds indicate that ELA depression ranged from c. 700 m in the Cordillera Blanca to c. 1200 m on the east side of the Cordillera Oriental. This augments data from many mountain ranges in middle‐ and low‐latitude regions that indicate that ELAs during the LGM were depressed by c. 1000 m. Published palynological evidence for drier conditions during the LGM in the tropical Andes suggests that ELA depression of this amount involved a temperature reduction (> 5–6°C) that greatly exceeded the tropical sea‐surface temperature depression estimates of CLIMAP (< 2°C). The west to east increase in ELA depression during the LGM indicates that the steep modern precipitation gradients may have been even steeper during the LGM.
Blanket mire formation at the Cross Lochs, Sutherland, northern Scotland
Authors: CHARMAN DANIEL J.
Published: July 2010

A brief review of the genesis of blanket peats is presented, together with detailed analyses of basal peats from northern Scotland. Particular attention is paid to local factors affecting peat growth and the problems of sampling and interpretation arising from them. Macrofossil and loss‐on‐ignition analyses of four peat‐mineral interfaces solve many of the terminological problems of such profiles and indicate that interpretations based on field stratigraphy alone are uncertain. Pollen analyses of two profiles from contrasting microtopographic situations show well‐defined vegetational change associated with early peat development. Fully organic ombrotrophic peat is present from 6805 ± 50 BP at one site, following anthropogenic burning from c. 7500 BP and partial recovery of the open birch woodland. A change from birch woodland to Calluna heath occurs at approximately the same time on a more freely drained site with much later peat development, following further burning from 4890 ± 65 BP. Anthropogenic activity is clearly associated with changes in soil and vegetation preceding peat formation, and the role of climatic factors remains equivocal.
Radiocarbon dating of the Goti‐Finiglacial boundary of the Swedish Time Scale
Authors: BRUNNBERG LARS , POSSNERT GÖRAN
Published: July 2010

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.
Multiple glaciations and sea level changes, northern Ellesmere Island, high arctic Canada
Authors: LEMMEN DONALD S. , ENGLAND JOHN
Published: July 2010

Along the northern coasts of Ellesmere Island, at least two glaciations are recognized on the basis of morphostratigraphy. The early Holocene ice limit lay only 5 to 60 km beyond present glaciers due to constraints imposed by aridity and calving. This limited ice advance likely extended beyond any Wisconsinan glacial limit. Marine limits established during, retreat from the last glacial maximum reach 148 m a.s.l. In contrast, earlier, more extensive glaciations inundated the coastlines and are associated with former relative sea levels now reaching 286 m a.s.l. Correlation of these pre‐Wisconsinan glaciations is based upon amino acid ratios. However, this approach is severely limited by slow rates of racemization, a lack ofin situsamples, and complex thermal histories owing to multiple transgressions. Models favoring extensive regional glaciation of northern Ellesmere Island and Greenland must include a glacioclimatic scenario recognizing the constraint that aridity places on glaciation. We suggest that the large ice volume associated with the oldest recognized glaciation relates to a period of reduced sea‐ice cover, possibly >400,000 BP, and may correlate with an interglacial stage of the marine oxygen isotope record.
A Silurian–Devonian acritarch flora from Saalian till in The Netherlands
Authors: VAN DER MEER JAAP J. M. , WICANDER REED
Published: July 2010

Micropaleontological analysis of a silt intraclast in till exposed near Steenwijk in the northern Netherlands revealed an acritarch flora of Late Silurian–Early Devonian age, of southeastern Baltic Basin origin. The age of this assemblage contrasts with what is known about the palynomorph content of Dutch tills. Petrologic analysis of the silt intraclast provides further insight in the direction and mode of Saalian glacier transport.
Gould Pond, Maine: late‐glacial transitions from marine to upland environments
Authors: ANDERSON R. SCOTT , JACOBSON GEORGE L. , DAVIS RONALD B. , STUCKENRATH ROBERT
Published: July 2010

Gould Pond sediments are unusual in North America in that they include a continuous record of change from marine to freshwater conditions during the late‐glacial period, with a wide array of micro‐ and macrofossils deposited during a period of high sedimentation rate. Marine waters, much colder than those in the present Gulf of Maine, covered the site at the time of deglaciation (c. 13,200 BP). Plants characteristic of modem tundra grew on nearby uplands. Marine recession, due to isostatic rebound of the land, occurred from c. 12,800–12,200 BP. The lake water was completely freshened by 12,000 BP. A sparse shrub‐herb tundra became established around Gould Pond as marine waters receded. Subsequent to 11,300 BP, sedges and other herbs became more abundant, and willow and Dryas less abundant, signifying increased warmth and decreased frost action. At least six tree species, all now common in the area, arrived around Gould Pond between c. 10,800 and 10,500 BP. This rapid transition was coincident with the most rapid major non‐anthropogenic change of vegetation at sites across eastern North America during the postglacial period.
Moraine‐ridge formation along a stationary ice front in Iceland
Authors: KRÜGER JOHANNES
Published: July 2010

At present the north margin of the temperate ice‐cap Myrdalsjökull is stationary: the ice edge retreats slowly during summer and readvances during winter to much the same position as the previous winter. Although the ice margin in this way has been stationary since around 1984. a frontal moraine ridge. 1.5‐2.5 m high. was under formation in 1986. and in 1989 it was 3–4 m high. The interior of the ridge appeared as imbricately stacked slabs of frozen, clast‐paved lodgement till dipping up‐glacier. At least five to seven slabs were identified in the 1989 ridge. The most proximal one was frozen to the up‐arched glacier sole and dipped beneath the glacier at about 30. In 1989 the volume of lodgement till sediments within the ridge represented a horizontal shortening of the ground moraine of roughly 60–90 m. On the other hand. between 1984 and 1989 the lateral displacement of the ridge toe amounted to only 10 m. It is concluded that the frontal ridge is formed progressively. not like conventional push moraines by thrusting of contemporaneous proglacial or ice‐contact sediments. but chiefly by a combination of basal freezing beneath the thin. clast‐loaded glacier toe each winter and recurrent superposition of frozen lodgement till slabs during small winter readvances.
AMS dating Swedish varved clays of the last glacial/interglacial transition and the potential/difficulties of calibrating Late Weichselian ‘absolute’ chronologies
Authors: WOHLFARTH BARBARA , BJÖRCK SVANTE , POSSNERT GÖRAN , LEMDAHL GEOFFREY , BRUNNBERG LARS , ISING JONAS , OLSSON SIV , SVENSSON NILS‐OLF
Published: July 2010

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.
European climates
Authors: MATTSSON JAN O.
Published: July 2010

Frenzel, B., Pfister, C. & Gläser, B. (eds.) 1992: European Climate Reconstructed from Documentary Data: Methods and Results.
Holocene palaeoenvironments at the timberline in the French Alps—a multidisciplinary approach
Authors: TESSIER LUCIEN , BEAULIEU JACQUES‐LOUIS DE , COUTEAUX MICHEL , EDOUARD JEAN‐LOUIS , PONEL PHILIPPE , ROLANDO CHRISTIANE , THINON MICHEL , THOMAS ANDRE , TOBOLSKI KAZIMIR
Published: July 2010

An attempt is made to reconstruct the palaeoenvironmental Holocene history at the timberline on the basis of the analysis of various palaeoecological proxy indicators available on a marshy area and its surroundings in the Taillefer Massif (Isère. France). The multidisciplinary approach involves analyses of pollen assemblages. plant macrofossils, coleoptera remains. subfossil trunks extracted from lakes or peat‐bogs. and charcoals derived from the surrounding soils. This enables definition of the respective roles of five forest taxa (Pinus uncinata Mill., Pinus cembra L., Larix decidua Mill., Abies alba Mill, and Picea abies L. Karsten) in the evolution of high altitude forests during the Holocene. Pinus uncinata was present on the plateau throughout the Holocene. Larix and Pinus cembra were present only during two periods: 7500‐5000 BP and 3500‐2000 BP. All trees disappeared from the plateau at about 2000 BP, while, at lower altitude. Abies was replaced by Picea. The action of both climate and early human impact can explain these changes.
The Quaternary of the Kattegat area, Scandinavia: a review
Authors: LYKKE‐ANDERSEN HOLGER , KNUDSEN KAREN LUISE , CHRISTIANSEN CHRISTIAN
Published: July 2010

The Quaternary sedimentary history and its relations to the pre‐Quaternary in the Kattegat region are reviewed. The Quaternary in the area is restricted to relatively young sediments, including scattered findings of Saalian deposits and more continuous occurrences from the Eemian, the Weichselian and the Holocene. Glacial and interglacial palaeoenvironmental reconstructions, including Holocene changes in oceanographic circulation, are reviewed, and the recent sedimentary processes and the present hydrographic regime are outlined. Furthermore, Quaternary and present tectonic activity in connection with some of the pre‐Quaternary fault zones is discussed.
Temperature oscillations over the last 10,000 years in western Europe estimated from terrestrial mollusc assemblages
Authors: ROUSSEAU DENIS‐DIDIER , LIMONDIN NICOLE , MAGNIN FRÉDÉRIC , PUISSEGUR JEAN‐JACQUES
Published: July 2010

Snail assemblages are used to estimate February and August temperatures during the past 10,000 years in western Europe. We find that a strong warming occurred after the Younger Dryas event, followed by several rapid cooling and warming events. These observations are in agreement with insect and pollen proxy data from the European continent and with estimates of sea‐surface temperature from the North Atlantic Ocean as well as with fluctuations of glaciers in western Norway. This study also confirms that terrestrial molluscs can provide reliable climatic data in conjunction with other proxy data.
The glacially sculptured landscape in Dronning Maud Land, Antarctica, formed by wet‐based mountain glaciation and not by the present ice sheet
Authors: HOLMLUND PER , NÄSLUND JENS‐OVE
Published: July 2010

The glacial landscape beneath the Maudheimvidda ice sheet in East Antarctica was most probably formed during a more temperate phase of Antarctic glaciation than the present. Overdeepened glacial cirques and U‐shaped valleys are found in the Heimefrontfjella and Vestfjella mountain ranges. These glacial landforms, located beneath the ice sheet, have been mapped with radio‐echo sounders. The present ice sheet covering these landforms is cold and frozen to its bed, and has a negligible erosive effect on the substrate. Ice sheet thickening during the Quaternary glacial periods is not believed to have caused any significant increase in erosion at the investigated sites. Instead, the glacial morphology was most likely formed by smaller, temperate glaciers when the Antarctic climate was warmer than at present. Datings of foraminifera and ash layers from the Transantarc‐tic Mountains indicate that the present cold ice sheet was formed 2.5 Ma years ago. Other studies imply that a cold Antarctic ice sheet has lasted even longer. The glacial landforms in Maudheimvidda may thus be of a pre‐Quaternary age.
The distribution of different glacial landscapes on southern Jameson Land, East Greenland, according to Landsat Thematic Mapper Data
Authors: RONNERT LARS , NYBORG MATS R.
Published: July 2010

Four geologic units previously mapped in southern Jameson Land. East Greenland (Funder 1978, 1990) are identifiable on a false colour composite of Landsat Thematic Mapper (TM) spectral hands TM5. TM4 and TM1. The area covered by the Weichselian glaciations has a fresh glacial morphology and a less developed drainage system than the older landscape. The Weichselian glaciers reached more than 200 m a.s.l. in the west. but only about 100 m a.s.l. in the east. A contextual analysis (local frequency and local orientation) was included in a Maximum Likelihood classification (M‐L) to map the extent of the Weichselian glaciations. Deposits correlated with the Saalian Scoreshy Sund glaciation are found on the central plateaux of Jameson Land. Landsat TM geological mapping of the surficial distribution of deposits from the Scoreshy Sund glaciation and of weathered Jurassic sandstone or deposits with a high percentage of such sandstone was done using a supervised Maximum Likelihood procedure. Except for the mapping of thc extent of the Late Weichselian Flakkerhuk glaciation, the Maximum Likelihood boundaries between units are in general agrecnient with earlier mapping or with the visual interpretation of the false colour composite. A strong vegetational influence. and similar spectral reflectance lrom deposits of different age due to similarities in lithological composition reduced the possibility of an independent remote sensing approach. Taking already existing general geological knowledge and chronology into account allowed successful Landsat TM geological mapping.
Weathering of surface clasts as an indicator of the relative age of glacial deposits on Jameson Land, East Greenland
Authors: LlLLIESKÖLD MARIANNE , SUNDQVIST BJÖRN
Published: July 2010

The relative age of glacial deposits on Jameson Land was investigated by weathering‐based techniques. Two related methods, measurement of rind thickness and of Schmidt hammer rebound values. were added to a dating programme of luminescence‐, amino acid‐ and 14C‐analyses. Rind thicknesses differ significantly between areas which represent three glacial phascs, spanning a time interval from late Saale to Late Weichselian. Rebound values are more susceptible to external factors than the rind values but may, if these external factors are known, serve as a complement to the interpretation of rind development.
Bryophytes from the last interglacial/glacial cycle, Jameson Land, East Greenland
Authors: HEDENÄS LARS
Published: July 2010

Subfossil bryophyte remains from Jameson Land, central East Greenland reveal diverse moss floras from the Langelandselv interglacial and the Hugin Sø interstadial. Around 30 species are reported as new subfossils from Greenland, indicating our insufficient knowledge of earlier bryophyte floras in the area. Among the species found from the Langelandselv interglacial. Several are southern and do not reach as far north as Jameson Land today, thus indicating a slightly warmer climate than at present in the area. The climate indications for the Hugin Sø interstadial are less clear, and further studies are necessary before delinitivc conclusions can he drawn. A large proportion of the found taxa indicate mineral‐rich or intermediately mineral‐rich conditions. Several wetland species indicate moving water, and a few sometimes or exclusively (Sanionia nivalis) occur in connection with late snow beds or meltwater brooks. Abundant material or the Polytrichaceae and ofRacomitrumindicates that more or less unstable soil. with sparse vascular plant cover, was relatively abundant.
Stratigraphy of a Late Pleistocene ice‐cored moraine at Kap Herschell, Northeast Greenland
Authors: HOUMARK‐NIELSEN MICHAEL , HANSEN LOUISE , JØRGENSEN MORTEN EJSING , KRONBORG CHRISTIAN
Published: July 2010

At Kap Herschell, in the outer fjord zone of central northeast Greenland, exposed sections in a Late Pleistocene ice‐cored moraine revealed four major stratigraphic units deposited during the complexKap Herschell Stade. All contain fragmented and redeposited marine shells that most likely belong to an Eemian or Early Weichselian marine episode. The oldest unit consists of buried ground ice with folded and sheared debris bands. Isotopic analyses show that the slope of the regression line for δ2H vs. δ18O of the ice is about 8.5. which suggests correlation with the Global Meteoric Water Line (GMWL). Data strongly suggest that the ground ice at Kap Herschell is a remnant of a Late Pleistocene glacier. It was probably generated at low altitudes (< 1000 m) in the inner fjord region or in the nunatak zone. The ground ice is unconformably overlain by all younger stratigraphic units, the oldest of which is a diamicton probably deposited as ablation till from the ice. A complex unit composed of mainly glaciolacustrine deposits and subordinate beds of fluvial and deltaic origin overlies the till and ground ice. Luminescence dating of the lacustrine sediments indicates maximum ages younger than 43 ka BP, suggesting deposition during isotope stages 3 or 2. The glaciolacustrine deposits suffered strongly from glaciotectonic deformation, caused by renewed glacier advance through the fjord. It reached the inner shelf and led to deposition of a discordant till at Kap Herschell, most probably during the Late Weichselian.
Luminescence dating of Late Quaternary sediments from East Greenland
Authors: MEJDAHL VAGN , FUNDER SVEND
Published: July 2010

Luminescence dating based on K‐feldspars and using both TL and OSL methods have been performed on 94 sediment samples from East Greenland. The ages go back more than 380 ka, but are mainly from the last interglaciation and the subsequent period and include both shallow‐marine/coastal‐fluvial and ice proximal meltwater sediments. Independent age control indicates that the dates in the first group generally fall within ± 15% of the expected age, although a few samples show larger deviations. The ice proximal sediments, on the other hand, show a much larger spread and exaggerated ages, probably owing to incomplete bleaching. OSL may give better results than TL in these sediments.
Relative sea‐level history and isostatic rebound in Newfoundland, Canada
Authors: LIVERMAN DAVID G. E.
Published: July 2010

The island of Newfoundland, Canada, is situated close to the former margins of the Laurentide ice sheet. The post‐glacial sea‐level history is complex, dominated by the effects of an ice‐marginal crustal forebulge produced by isostatic deformation of the lithosphere. Marine fossils found above present sea‐level can be 14C dated, and examination of the temporal and geographical distribution of these 14C dates in combination with geomorphological indicators of past sea‐levels indicates regional trends of relative sea‐level change. For most of the island (apart from the Northern Peninsula) no samples have been recovered that date younger than 8000 BP. suggesting that sea‐level lay below the present one in these areas for the last 8000 years. The same areas commonly show geomorphological evidence for stands of sea‐level both above and below present sea‐level. This evidence is interpreted as showing that over most of Newfoundland, following deglaciation, sea‐level fell to below present levels, and subsequently rose to the modern level. Exceptions to this pattern are the north of the Northern Peninsula, which shows a history of continuous emergence, or a more complex pattern of sea‐levels falling below present, subsequently rising above present, and currently falling; and the northeast Avalon Peninsula, which may have had sea‐levels below present throughout post glacial times. This pattern of relative sea‐level change is interpreted as being mostly due to isostatic recovery, with the main factor being northerly migration of the forebulge. Mapping the time at which sea‐level fell below the present level allows estimation of the rate of northerly migration and collapse of the forebulge at between 4.5 and 11 km/100 years; this is considerably faster than previous estimates.
Dating of the near‐surface layer of a peatland in northwestern Ontario, Canada
Authors: BELYEA LISA R. , WARNER BARRY G.
Published: July 2010

The near‐surface layer of the dominant microhabitat types on a peatland in the Rainy River area, northwestern Ontario, Canada was dated using a number of previously published methods. No single method was found to be appropriate in all microhabitat types, and discrepancies of up to 15 yr over a time‐scale of 80 yr were encountered. The results suggested that the post‐depositional mobility of 210Pb, and possibly its atmospheric supply, are affected by microhabitat type. 210Pb dates consistently underestimated independently derived dates in the uppermost sections of the cores. Ages derived by measuring the length of annual increments on moss stems were in general agreement with the 210Pb dates, but were subject to bias where the moss remains were poorly preserved. 14C analyses on material from the base to the near‐surface horizon confirmed the modern (post‐AD 1950) origin suggested by the 210Pb and moss increment dates. Increased ash content at the base of the near‐surface layer was correlated with the dustbowl of the 1930s, but assignment of dates to other stratigraphic markers (charcoal, Ambrosia pollen, and Larix needles) was less certain. The ash peak (55 yr before AD 1990) was used as datum for relative dating methods based on assumptions of a constant rate of peat accumulation (constant bulk density method) and constant rate of pollen accumulation (pollen density method). The constant bulk density method provided quick, inexpensive estimates of maximum age, but could not be extrapolated beyond datum, nor applied to cores showing marked stratigraphic changes. The pollen density method was a valuable but time‐consuming alternative for dating peatland depressions, which lack annual moss increments and are subject to 210Pb leaching.
Influence of Southern Upland ice on glacio‐isostatic rebound in Scotland: the Main Rock Platform in the Firth of Clyde
Authors: GRAY J. MURRAY
Published: July 2010

This paper identifies an anomaly between the currently acccpted isobasc pattern for raised shorelines in Scotland. which is a simple ellipsoid centred over the Western Highlands, and current models for the morphology of the Late Devensian ice‐sheet. which show a primary dome in the Western Highlands but a prominent secondary dome over the Southern Uplands. One explanation of this anomaly is that it is an artefact of inadequate shoreline data for south‐west Scotland. To test this hypothesis, altitude data on the Main Rock Platform in the Firth of Clyde area have been collected and analysed. and demonstrate patterns that probably result from the influence of Southern Upland ice. The ice‐sheet models in this area are therefore supported.
Younger Dryas and early Holocene lake‐level fluctuations in the Jura mountains, France
Authors: MAGNY MICHEL , RUFFALDI PASCALE
Published: July 2010

Lake‐level fluctuations in the Jura mountains (France) during the Younger Dryas and the early Holocene are reconstructed using sedimentological analyses. Major transgressive phases culminated just before the Laacher See tephra deposition, at the beginning of the Younger Dryas, between 9000 and 8000 BP and between 7000 and 6000 BP. The Younger Dryas appears to be characterized by increasing dryness. Other major lowering phases occurred during the middle Allerød and during the Preboreal. A transgressive event developed betweenc. 9700 and 9500 BP. These palaeohydrological changes can be related to climatic oscillations reconstructed from pollen and isotopic records in Swiss lakes, from glacier movements and timberline variations in the Alps, and from isotopic records in the Greenland ice sheet.
Late Weichselian ice‐sheet sensitivity over Franz Josef Land, Russian High Arctic, from numerical modelling experiments
Authors: SIEGERT MARTIN J. , DOWDESWELL JULIAN A.
Published: July 2010

A numerical ice‐sheet model was run in order to produce reconstructions of the Late Weichselian ice coverage of Franz Josef Land, Russian High Arctic. The model grid covers the archipelago and surrounding shelf, but does not include the whole Barents‐Kara region or the extensive ice cover that may have built up there. One experiment, where rates of iceberg calving at the grounded margin were curtailed because of the assumed presence of permanent thick sea ice, yielded a single I.8 km‐thick ice dome which covered the entire archipelago and surrounding sea. If, however, iceberg calving were included in the model's environmental input, the extent of the ice sheet would be limited to the periphery of the archipelago. If a large ice sheet existed over Franz Josef Land, the deglaciation of the islands may have been linked to the decay of the adjacent Barents‐Kara Sea Ice Sheet, permitting iceberg calving (enhanced by relative sea‐level rise) to occur. The introduction of a water‐depth‐related iceberg calving function at 15 000 yr ago forced an initial rapid rate of ice‐sheet decay of 30 000 km3 1000 yr'. However, as the ice sheet thinned, and isostatic rebound began, the calculated rate of iceberg calving was reduced such that ice remained over the archipelago at 8000 yr ago. The model's failure to simulate complete ice‐sheet decay by 8000 yr ago is at variance with radiocarbon‐dated raised terraces on Franz Josef Land, which indicates the complete deglaciation of the islands at this time.
The occurrence of Laacher See Tephra in Pomerania, NW Poland
Authors: JUVIGNÉ ÉTIENNE , KOZARSKI STEFAN , NOWACZYK BOLESLAW
Published: July 2010

A millimetre‐thick bed of highly vesiculated pumiceous clasts was found in two peat bogs in Pomerania (NW Poland). Their phonolitic composition confirms the correlation with the Laacher See Tephra (LST). Based on the various CaO‐Na2O‐K2O content, most of these clasts can be linked with the Lower Laacher See Tephra (LLST), and some with the Middle Laacher See Tephra B (MLST‐B).14C dates obtained on peat samples are in agreement with an Allered stratigraphic position of that tephra. In several localities in NW Poland, it was found that there was no occurrence of tephra in peat bogs. Thus the presence of the LST is restricted to the northwestern fringes of Pomerania.