bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid isostatic rebound in southwestern Iceland at the end of the last glaciation
Authors: INGÓLFSSON ÓLAFUR , NORDDAHL HREGGVIDUR , HAFLIDASON HAFLIDI
Published: July 2010

In connection with a new deglaciation concept for Iceland, implying an extensive glaciation during the Younger Dryas and the decay of the Icelandic inland ice sheet during the Preboreal, the history of relative sea‐level changes on Iceland has been re‐evaluated. New field data from the Reykjavik area, in Faxaflói Bay southwestern Iceland, were obtained in order to construct the first stratigraphically controlled curve of relative sea‐level displacements for Iceland. The curve is constructed on the basis of radiocarbon‐dated shells in raised marine deposits and on tephrostratigraphically controlled and radiocarbon‐dated, submerged peat deposits. The curve suggests that a post‐glacial relative sea‐level change of about 45 m, from + 43 m a.s.1. to — 2 m a.s.l, occurred over a period of 900 14C‐years in the Reykjavik area between 10 300 BP and 9400 BP. The sea‐level curve shows a shoreline displacement of c. 5 cm 14Cyr‐1 for that period. The mean absolute uplift rate is calculated to be 6.9 cm 14C yr‐1, which is about double the fastest rate reported from any other coastal North Atlantic site. Although this rapid uplift can probably be partly explained by a 14C plateau around the termination of the Pleistocene, it is more than likely controlled by rapid Preboreal deglaciation, together with low asthenosphere viscosities below Iceland and the release of hydroisostatic stresses in connection with the deglaciation.
Involutions in the Middle Pleistocene (Anglian) Barham Soil, eastern England: a comparison with thermokarst involutions from arctic Canada
Authors: MURTON JULIAN B. , WHITEMAN COLIN A. , ALLEN PETER
Published: July 2010

Involutions in the early Anglian Barham Soil at Newney Green, Essex, and Badwell Ash, Suffolk, in eastern England, are attributed to soft‐sediment deformation during an episode of regional thermokarst development. The involutions show a striking resemblance in morphology and size to thermokarst involutions within a palaeo‐thaw layer at Crumbling Point, western arctic Canada. By analogy with the thermokarst involutions, the involutions in the Barham Soil are reinterpreted to have formed by loading during the melting of an ice‐rich layer at the top of Anglian permafrost. This period of thermokarst development may have coincided with an episode of intra‐Anglian climatic amelioration. Reinterpretation of the Barham Soil involutions implies that many other Pleistocene involutions in Britain may have formed during periods of thermokarst development rather than by active‐layer cryoturbation.
Ecological, sedimentary, and geochemical evolution of the late‐glacial to postglacial Åmose lacustrine basin, Denmark
Authors: PETERSEN KAJ STRAND
Published: July 2010

Noe‐Nygaard. Nanna. 1995: Ecologicol, Sedimentary, trnd Geonchemical Evolution of the Late‐glarcial to Postglacial Åmiose Locustrine Basin. Denmark. Fossils and Strata
Subglacial and subaqueous processes near a glacier grounding line: sedimentological evidence from a former ice‐dammed lake, Achnasheen Scotland
Authors: BENN DOUGLAS I.
Published: July 2010

Subglacial and subaqueous sediments deposited near the margin of a Late‐glacial ice‐dammed lake near Achnasheen, northern Scotland, are described and interpreted. The subglacial sediments consist of deformation tills and glacitectonites derived from pre‐existing glaciolacustrine deposits, and the subaqueous sediments consist of ice‐proximal outwash and sediment flow deposits, and distal turbidites. Sediment was delivered from the glacier to the lake by two main processes: (1) subglacial till deformation, which fed debris flows at the grounding line; and (2) meltwater transport, which fed sediment‐gravity flows on prograding outwash fans. Beyond the ice‐marginal environment, deposition was from turbidity currents, ice‐rafting and settling of suspended sediments. The exposures support the conclusion that the presence of a subglacial deforming layer can exert an important influence on sedimentation at the grounding lines of calving glaciers.
Early stages of till genesis: an example from Fanore, County Clare, Ireland
Authors: CROOT DAVID G. , SIMS PETER C.
Published: July 2010

Traditional views of glacigenic processes focus on erosion of hard bedrock and deposition of unconsolidated till. In the 1960s and 1970s attention was directed towards the glacier debris cascade, which linked these two end members. A limited understanding of the relationship between bedrock character, the supposed processes of erosion, debris comminution and texture emerged. In the 1980s researchers began to appreciate the important role which glaciotectonism plays in the spectrum of glacigenic processes, although little attention has been paid to the interface between glacial erosion, glaciotectonism and the early stages of the debris cascade system. A coastal section at Fanore, County Clare, Ireland affords a unique opportunity to examine a range of glacial deposits which represent a series in the erosion, tectonism and comminution stages of till genesis. Major elements of the site are bedrock rafts, glaciotectonic breecias, immature till and mature till. In all cases > 98% of the elements comprise Carboniferous limestone. Research at Fanore has focused on textural properties. Analysis of bulk samples of the sediments demonstrates a continuum of textural development from the glaciotectonism of the bedrock (breecia production and bedrock raft comminution) to a homogenized but immature till and to a more mature matrix‐dominated deposit.
Palaeoenvironments in the Skagerrak‐Kattegat basin in the eastern North Sea during the last deglaciation
Authors: KNUDSEN KAREN LUTSE , CONRADSEN KELD , HEIER‐NIELSEN SUSANNE , SEIDENKRANTZ MARIT‐SOLVEIG
Published: July 2010

The study of a c. 18 m thick Late Weichselian‐ Early Holocene (isotope stage 2/1) marine succession (original water depth 100–150 m) from the Skagen 3 borehole, northern Denmark, has led to a better understanding of the palaeoenvironmental changes during the last deglaciation. The palaeoenvironmental interpretation is based on benthic foraminifera, stable isotope composition and lithology, whereas the chronostratigraphy and sedimentation rates are based on AMS radiocarbon dates. Marine conditions were established in the area at between 15 000 and 14 500 BP (reservoir corrected14C years), and the first influence of Atlantic water masses imported through the Norwegian Channel is registered from 13 100 BP to 10 900BP (the Bølling‐ Allerrad interstadial complex). This was followed by the Younger Dryas cooling event between 10 900 and 10 100 BP. The hydrographic change at the Pleistocene‐Holocene transition after the Younger Dryas occurred in two stages. Arctic/subarctic deep‐water assemblages persisted continuously at Skagen after the first stage at 10 200 BP, while cold boreal assemblages existed in shallower water environments in the Kattegat‐Skagerrak basin during the same period of time. The slight warming in the early Holocene seems to have been interrupted by a short‐term cooling at about 9700–9600 BP. Finally, at 9600 BP the arrival of warm Atlantic water masses created full‐interglacial conditions in the whole region.
Climatic reconstructions from the Eemian/Early Weichselian transition in Central Europe based on the coleopteran record from Gröbern, Germany
Authors: WALKLING ADRIAN P. , COOPE G. RUSSELL
Published: July 2010

At Grobern (51°52′N, 12°6′E, altitude 94–98 m a.s.l., 50km north of Leipzig), a succession of lacustrine sediments has yielded a fossil coleopterous fauna permitting the reconstruction of climatic conditions through out the Eemian/Early Weichselian transition. In accord with other indicators, the Coleoptera show that this period was characterized by three major climatic oscillations during which the thermal climate fluctuated between conditions of arctic severity and more temperate conditions. During the cold episodes, the beetle faunas were dominated by species which today have exclusively northern or even Asiatic ranges. In the intervening warm periods these cold‐adapted species were absent and the faunas included temperate species some of which are tree‐dependent. Quantitative palaeotemperature estimates using the Mutual Climatic Range method, show that the mean July temperatures during the relatively colder intervals were 5°C to 6°C lower than during the warmer periods, but the depression of winter temperatures during the colder periods was much greater than this. Because different species of Coleoptera have different thresholds of temperature tolerance, their indications of climatic change do not always coincide with the changes in the lithology or pollen.
Where the ice meets the sea ‐ high resolution paleoenvironmental studies in the northern North Atlantic
Authors: KEIGWIN LLOYD D.
Published: July 2010

Andrews, J. T., Austin, W. E. N., Bergsten, H. & Jennings, A. E. (eds), 1996: Late Quaternary Paleoceanography of the North Atlantic Margins
Holocene pollen stratigraphy and bog development in the western part of the Kola Peninsula, Russia
Authors: KREMENETSKI CONSTANTIN , VASCHALOVA TATIANA , GORIACHKIN SERGEI , CHERKINSKY ALEXANDR , SULERZHITSKY LEOPOLD
Published: July 2010

Pollen and macrofossil investigations and radiocarbon datings were carried out at a bog in the Khibiny mountains and the northernmost bog in European Russia on the Rybachiy Peninsula (69°98'N) on the western part of the Kola Peninsula. Peat accumulation on the Kola Peninsula started at c. 8500–7500 BP. Pinus sylvestris reached its present northern limit on the peninsula by 7000 BP, while 6000–5000/4500 BP was a time of maximal progress of birch forest tundra up to the Barents Sea shoreline. Alnus ineana grew up to the Rybachiy Peninsula c. 40 km north of its present‐day northern limit. By c, 5500/5300 BP Picen ohovata had immigrated to the Khibiny mountains. After 5000/4500 BP the forested area had retreated in the northern part of the Kola Peninsula and the tundra belt bordering the Barents Sea shore was formed. By 3500 BP spruce had reached its modern northern limit.
Palaeohydrology and global continental changes ‐ panta rhei?
Authors: PIOTROWSKI JAN
Published: July 2010

Branson, J., Brown, A. G. & Gregory, K. J. (cds.) 1996: Glubai Continental Changes: The Context of Palaeohydrology
Pre‐Younger Dryas resurgence of the southwestern margin of the Cordilleran ice sheet, British Columbia, Canada
Authors: CLAGUE JOHN J. , MATHEWES R. W. , GUILBAULT J.‐P. , HUTCHINSON I. , RICKETTS B. D.
Published: July 2010

Clague, J. J., Mathewes, R. W., Guilbault, J.‐P., Hutchinson, I. & Ricketts, B. D. 1997 (September): Pre‐Younger Dryas resurgence of the southwestern margin of the Cordilleran ice sheet, British Columbia, Canada. Boreas, Vol. 26, pp. 261–278. Oslo. ISSN 0300–9483.

A lobe of the Cordilleran ice sheet readvanced into the central Fvaser Lowland, southwestern British Columbia, Canada, on at least two occasions near the end of the last glaciation. This ice also flowed into the previously deglaciated, lower reaches of mountain valleys adjacent to the Fraser Lowland and into Washington state. The first of these advances occurred before about 11900 BP and ended with glacier retreat and the establishment of lodgepole pine forest on newly deglaciated terrain. Parts of this forest were overridden by ice during a second advance, shortly after 11300 BP. The younger advance is most likely older than the Younger Dryas Chronozone (11000–10000 BP) and may correlate with an intra‐Allerad cooling event (the Killarney‐Gerzensee oscillation). The older advance may have occurred during the Oldest Dryas or Older Dryas cold period. Non‐climatic factors could also be involved, as emergence of the Fraser Lowland before the older advance greatly reduced or eliminated calving at the glacier margin and thus altered the mass balance of the ice lobe.
A new middle Holocene varve diagram from the river Ångermanalven, northern Sweden: indications for a possible error in the Holocene varve chronology
Authors: WOHLFARTH BARBARA , BJÖRCK SVANTE , CATO INGEMAR , POSSNERT GÖRAN
Published: July 2010

A new varve diagram from the river Ångermanälven could be correlated to the postglacial varve chronology to between 4903 and 4415 varve years BP. An AMS 14C measurement on terrestrial macrofossils obtained between 4715 and 4706 varve years BP gave a calibrated age of between 5730 and 5040 calendar years BP. The discrepancy between varve and calender‐year age indicates that an error or part of an error in the Swedish varve chronology may be situated between 2000 and 5000 varve years BP.
Sediment record of short‐lived ice‐contact lakes, Burroughs Glacier, Alaska
Authors: SYVERSON KENT M.
Published: July 2010

Sediments deposited in two small ice‐contact lakes with low rates of sediment input have been studied in subaerial exposures. Sediment characteristics are a function of the water source (glacial meltwater versus non‐meltwater), proximity to the glacier margin and lake shore, amount of supraglacial debris, and lake duration. Calving Lake expanded (and later partially drained) as a calving ice margin retreated. Nearshore deltas contain 1 × 105 m3 stratified sand and gravel deposited at rates up to 1 m/yr during a 9‐yr interval. Deltaic sediment contains types A and B ripple‐drift cross‐lamination, draped lamination, and scour surfaces caused by variations in water‐flow velocity and the amount of sediment settling from suspension. Most water inflow came from non‐subglacial meltwater sources and was sediment‐poor, so overflow and interflow sedimentation processes dominated the offshore environment. Offshore sediment generally contains massive silt or silt interbedded with fine‐grained sand deposited at rates of 1.3‐1.5 cm/yr. Iceberg gravity craters observed on the lake plain were formed when icebergs impacted the lake floor during calving events. In Bruce Hills Lake, proximity to glacier ice and the presence of supraglacial sediment formed coarsening‐upward successions when debris fell directly from an ice ledge onto silty lacustrine sediment.
Lake‐tilting, a method for estimation of glacio‐isostatic uplift
Authors: PASSE TORE
Published: July 2010

A non‐uniform glacio‐isostatic uplift can result in differential uplift for different parts of a lake. If the lake outlet is situated in the area of the greatest rate of uplift, then remote parts of the lake will be continuously transgressed. Ancient lake levels can be estimated by dating transgressed peat at different depths in such lakes. Four lakes in southern Sweden have been investigated using this method and the course of the glacio‐isostatic uplift has been determined empirically. The investigation shows that the difference in uplift between the outlet and the sampling site can be expressed as an arctan function relating the difference in uplift over time to: half of the difference of the total uplift between the outlet and the sampling site, the time for the maximal rate of the uplift and a declining factor.
The European sand belt in eastern Europe ‐ and comparison of Late Glacial dune orientation with GCM simulation results
Authors: ZEEBERG JAAPJAN
Published: July 2010

A compilation is presented of the continuation of the European sand belt, east of Poland. Dune fields encompass most of the aeolian formations in eastern Europe. Supposed sand provenance, dune orientation, and the few available datings suggest initial aeolian activity during cold stages of the Upper‐Pleni (= full)glacial and Late Glacial, similar to northwest and central Europe. Dune fomiation was primarily supply controlled. Comparison of dune orientation with Late Glacial surface wind directions simulated by various GCMs permits reconstruction of dune activation with the positioning of (winter) westerlies over glacial deposits during the Oldest Dryas. Final widespread aeolian activity occurred during the Younger Dryas. As compared to the smaller fields toward the centre of deglaciation, aeolian sand deposits of the intermediate and periglacial zone benefited from distinctly longer intervals of accumulation. In the zone of deglaciation, aeolian activity was restricted to relatively isolated basins.
Zircon microstriators in the sand of auriferous Andean tills: fine tools and noble metals
Authors: MAHANEY WILLIAM C. , MILNER MICHAEL W.
Published: July 2010

Chemically inert and physically hard minerals, of which zircon is universally present and usually abundant, are minor but important components of glacial gold and tin placer deposits. Zircons and other much less common resistant minerals inflict major damage on light minerals, of which quartz is the dominant, chemically resistant member. Because of its sharpness inherited from a strong crystal morphology, and overall prismatic form, zircon is especially important as an abrasive mineral in glacial systems. Its chemically inert nature, its dominancc in terms of hardness over light minerals, and its abundance amongst other hard minerals makes it unique and important as a microstriator. Transported in a highly viscous glacial medium, it is capable of damaging other softer grains with aggressive crushing, chipping, striating, abrading and polishing processes. These occur in both coarse‐grained gravelly sand and in fine‐grained clayey silt matrices at the base of the icc. Zircon grains tend to serve many functions, initially as inclusion tools in larger feldspar grains and as ‘studs’ in quartzite grains. Wearing first on points, and later, following liberation, they assume a shape by honing, faceting and fracturing as tools and as grit that allows them to act as microstriators, inflicting damage on other particles in the basal ice. With a hardness of 7.5, lacking significant cleavage, and exhibiting strong crystal form. the finer‐grained zircons appear to abrade and striate quartz (hardness 7.0). feldspars (hardness 6.0). garnets (hardness 6.5–7.5), and gold (hardness 2.5‐3.0). A detailed study of Bolivian tills shows the dominant form of the zircon striator to be an elongate, pencil shape (euhedral polygonal prism with sharp, pyramidal terminations) that shows various degrees of abrasion, and ranges from wide grains with dull edges to narrow grains with sharp edges (typical pencil form).
Non‐analogous tree flora in the Scandes Mountains, Sweden, during the early Holocene ‐ macrofossil evidence of rapid geographic spread and response to palaeoclimate
Authors: KULLMAN LEIF
Published: July 2010

Early‐Holocene occurrences of broad‐leaved temperate tree species at a site now within the subalpine belt of the Swedish Scandes are reported and analysed. Macrofossil remains (fruits and leaves) of Alnus glutinosa, Corylus avellana, Quercus robur and Ulmu.s glahra were recovered in a peat deposit far beyond and above their modern distributional limits. A previous nearby finding of Tilia cantata adds to this group of Hemiboreal lowland species, the regional presence of which in high‐elevation northern Scandinavia has gone entirely unrecognized by pollen stratigraphical studies. Radiocarbon dates (AMS) range between 8500 and 8000 BP, indicating early and rapid spread, closely following the ice recession. Maximum tree species richness and distributional limits (latitude and altitude) were attained during the earliest part of the Holocene. In a regional perspective, the temperate trees coexisted with a dominant boreal (cold‐climate) element, viz. Pinus sylvestris, Bclulu pubescens ssp. tortuosa, Betula pendula, Alnus incana, Picea ahies and Larix sibirica, which are all identified and dated from macrofossils. This climatically seemingly incompatible assemblage is without modern analogues. Presumably, this diverse tree flora owed its existence to a unique (Holocene perspective) climatic regime, ultimately forced by the Milankovitch cycles of insolation. The results strengthen previous palaeoclimatic inferences based on past tree‐limit positions (Pinus sylvestris) and imply that Holocene summer warmth peaked fairly soon after the regional deglaciation, practically concurrently with the solar radiation maximum. Important questions are raised concerning several palynologically derived postulates within general palaeobiogeography. For example, rates of geographic tree spread are not necessarily individualistic, despite fundamentally different dispersal modes. The emergent efficiency of dispersal suggests that distribution patterns relate to climate and soil factors rather than time. Dispersal steps may have been fairly large, and the resultant geographic spread was epidemic, resulting in a sparse pattern of outlying stands, rather than sequentially following certain routes in the landscape. Rapid geographic expansion is likely to have been relatively unrestrained by physical barriers, e.g. mountain ranges, seas and large lakes. Even in Central Europe, close to the ice margin, there may have been more trees during the latest glaciation than previously realized.
Methods for preparing and counting biochemical varves
Authors: LOTTER ANDRÉ F. , LEMCKE GERRY
Published: July 2010

Four different preparation and counting methods for biochemical varves were compared in order to assess counting errors and to standardize these techniques. The properties of two embedding methods, namely the shock‐freeze, freeze‐dry and the water‐acetone‐epoxy‐exchange method, are discussed. Varve counts were carried out on fresh sediment and on sediment thin‐sections, on the latter by manual and by automated counting using image‐analysis software. Counting on fresh sediment and using image‐analysis generally underestimated the number of varves, especially in sections with inconspicuous varves. A comparison between multiple varve counts carried out by a single analyst and different analysts showed no significant differences in the mean varve counts.
Using whole rock geochemistry to locate the source of igneous erratics from drumlins on the Atlantic coast of Nova Scotia
Authors: STEA RUDOLPH R. , PE‐PIPER GEORGIA
Published: July 2010

Whole rock geochemistry has been determined for erratics from the surface Lawrencetown Till in two drumlins on the Atlantic coast of Nova Scotia. The geochemical data, particularly trace element composition, allow source rocks to be identified more precisely than by traditional petrographic microscopy. A drumlin near Lunenburg contains erratics of Neoproterozoic arc‐related plutonic rocks and basalts that outcrop only in a small area near Parrsboro in the Cobequid Highlands. Some associated erratics of granite precisely match a small late Devonian pluton in the same area and other granites and rhyolite could also be derived from late Devonian rocks in the same area. The type section of the Lawrencetown Till contains different Neoproterozoic plutonic rocks of a type found in the eastern Cobequid Highlands, together with a distinctive late Devonian granite with sodic amphiboles that is restricted to a small area near the Debert River. Both these source areas indicate a southward flow of ice (Escuminac Phase) depositing the Lawrencetown Till, in contrast to earlier southeastward‐flowing ice (Caledonia Phase) which deposited the Hartlen Till that forms the core of the drumlin. Drumlins in Nova Scotia are complex palimpsest landforms that were formed by till accretion, and evolved in surface form throughout multiple flow events.
Chemical kinetics, speleothem growth and climate
Authors: DREYBRODT WOLFGANG
Published: July 2010

The morphology and stratigraphy of speleothems are controlled by parameters that depend on climate. These are the water supply rates feeding the speleothem, e.g. a stalagmite, the growth rates dependent on the chemical kinetics of calcite precipitation and the supersaturation of the solution from which calcite is precipitated. To elucidate the basic principles of speleothem growth, a physical…chemical model of calcite precipitation is used to estimate growth rates under various geologically relevant conditions. Furthermore, we present a model that allows the computation of the growth history of stalagmites, i.e. their morphology and stratigraphy under varying climatic conditions. This enables us to see how climatic signals are inscribed into stalagmites. Owing to the counter‐balancing effects of some parameters, it is not possible to read climatic conditions backwards from the morphology and stratigraphy of a speleothem in a simple way, but a basic understanding of the growth of speleothems can be a helpful supporting tool in the interpretation of palaeoclimatic records.
The potential of perennial cave ice in isotope palaeoclimatology
Authors: YONGE CHARLES J. , MACDONALD WILLIAM D.
Published: July 2010

Perennial ice from caves on and to the east of the Canadian Great Divide yield δ18O and δD values, which are unusually high measurements when compared with the average precipitation for the region. Furthermore, these ice data fall below and along lines of lower slope than the Global Meteoric Water Line. To explain the observed relationships, we propose the following process. A vapour‐ice isotopic fractionation mechanism operates on warm‐season vapour when it precipitates as hoar ice on entering the caves. The subsequent fall of hoar to the cave floor through mechanical overloading, along with ice derived from ground‐water seepage (with a mean annual isotopic composition), results in massive ice formation of a mixed composition. This mixed composition is what is observed in the characteristic relationships found here. Such findings suggest that a warm versus cold climate interpretation for ancient cave ice may be the opposite of that found in the more familiar polar and glacial ice cores.
Twenty‐one years of string movements on the Liippasuo aapa mire, Finland
Authors: KOUTANIEMI LEO
Published: July 2010

The movements of four 80–100 m long strings crossing a 750 m long aapa mire were measured, and two pools were drained and local snow depth and ground frost conditions were observed in order to test the role of water pressure and ground frost in string motions. Located close to the Arctic Circle, Liippasuo is characterized by a maximal snow depth of about 1 m, a mean annual temperature of ‐1°C and a maximal variation in temperature of over 75°C. The strings moved at the rate of 50–150 cm in the course of 21 years. The most active parts were those located in the area of steepest gradient. Periods with normal annual shifts in the range 2–5 cm were interrupted from time to time by moves of abnormally high magnitude. This resulted in swelling of the nearby pools and increased curving of the strings, giving rise to a small‐scale zigzag course in the strings. The principal factors responsible for the motion were ice/frozen peat push, solifluction and water pressure. Movements occurred not only during the thawing period but also in summer‐time. They were as common in the direction of the contours as when following the slope. The unexpected uphill direction of movements is explained by winter‐time freezing and expansion of the whole mire, in the same way as the ice cover on a lake will expand as a result of temperature changes.
The Holocene history of the southwestern Baltic Sea as reflected in a sediment core from the Bornholm Basin
Authors: ANDRÉN ELINOR , ANDRÉN THOMAS , SOHLENIUS GUSTAV
Published: July 2010

A study of changes in siliceous microfossil assemblages and chemical analyses in a well‐dated offshore sediment core from the Bornholm Basin, southwestern Baltic Sea, is carried out with the objective of increasing knowledge of the Holocene history of the area. The core covers about 11300 calendar years from the brackish phase of the Yoldia Sea stage to the present. The first weak marine influence in the Ancylus Lake stage is recorded about 10100 cal. yr BP (c. 8900 14C BP), indicating a complex transition to the Litorina Sea with different phases of brackish‐water inflow. The lithology, organic carbon content and C/N and C/S ratios indicate no major changes in the sedimentary environment during the Litorina‐Post‐Litorina Sea stages. A high productivity event recorded in the Post‐Litorina Sea stage around 950 cal. yr BP correlates with the Medieval warm event. A biostratigraphical change indicating a colder climate is recorded in the sediment at about 800 cal. yr BP, which might mark the beginning of the Little Ice Age.
Late Weichselian glacial history and postglacial emergence of Phippsøya, Sjuøyane, northern Svalbard: a comparison of modelled and empirical estimates of a glacial‐rebound hinge line
Authors: FORMAN STEVEN L. , INGÓLFSSON ÓLAFUR
Published: July 2010

Field research on Phippsøya, the largest island in the Sjuøyane archipelago, defines the course and timing of postglacial emergence, documents past‐glacier movements, and reinterprets deglacial sedimentary sequences. Previously described tills were not identified in sections exposed along the northeast shore of Phippsøya, but instead sublittoral sediments with rock‐fall concentrations derived from the adjacent slope. A glacio‐isostatically higher sea level >40 ka deposited sublittoral sediment and is possibly correlative to a deglacial event in oxygen isotope stage 4 or 5 identified at other sites on Svalbard. The postglacial marine limit is 22 ± 1 m aht and occurs as an escarpment or washing limit into a stony drift. This drift contains granite and quartzite erratics from Nordaustlandet that indicate coverage by a northward flowing ice sheet during the Late Weichselian. Datable material on the raised‐beach sequence was rare and a 14C age of c. 9.2 ka on an articulated Balanus balanus from 10 m aht provides a minimum constraining age on the marine limit. A mild transgression occurred by 6.2 ka, with sea level falling close to present levels by c. 5.0 ka. The zone of zero emergence (hinge line) lies 10 to 20 km north of Sjuøyane and is approximately coincident with the last glacial maximum limit on the continental shelf. There is an approximately 75 to 100 km offset between observed and modelled zone of zero emergence, indicating a need to refine earth rheology‐based ice‐sheet models.
Comparative scanning electron microscopy study of oriented till blocks, glacial grains and Devonian sands in Estonia and Latvia
Authors: MAHANEY WILLIAM C. , KALM VOLLI
Published: July 2010

Samples of Middle Devonian (Eifelian age; 387–380 Ma) indurated and non‐cemented sandstone were compared with Pleistocene basal tills in Estonia and Latvia to test a hypothesis that glacial SEM (scanning electron microscopy) microtextures are distinctly different from those produced in a fluvial depositional environment. The deposits of Middle Devonian Aruküla Stage were emplaced in a continental water basin close to sea level and well away from any glacial source. Therefore, the SEM microtextures on quartz grains from the Aruküla Stage should show mainly the effect of stream transport. The basal tills are of Late Weichselian age deposited as ground moraine directly over the sandstone. Additional glaciofluvial and glaciolacustrine samples were included with the tills to determine whether glacial and fluvial‐lacustrine transport could be differentiated by the SEM microtextures. Samples of oriented blocks of till from a limited number of sites were studied without pretreatment to determine whether sand clast orientation could provide a method for determining glacial flow vectors. While there are some microtextural similarities between grains from glacial and glaciofluvial‐lacustrine depositional environments, the vast majority of grains from till deposits (50%–60%) are faceted, sharp edged, angular to subangular, and comprised of numerous and distinct microfeatures including abraded surfaces over microfractures, deep linear and curved troughs (striations), step features, and a preponderance of conchoidal and linear microfractures. Glaciofluvial and lacustrine grains contain abundant abrasion features and v‐shaped percussion cracks that make them very distinct from glacial grains. Fluvial transport produces primarily rounded grains, well abraded, with v‐shaped percussion scars dominating. Thus, it is possible to use microtextural differences between the three sample suites to identify particular depositional environments. Oriented till blocks provide information on sand clast orientation. Although carbonate coatings often obscure sand clasts in untreated blocks, it is possible to determine some microfabric information that can be useful in determining flow direction of the ice.
Late‐glacial climate in the Maritimes Region, Canada, reconstructed from mutual climatic range analysis of fossil Coleoptera
Authors: MILLER RANDALL F. , ELIAS SCOTT A.
Published: July 2010

Mean July and January temperatures are reconstructed from radiocarbon‐dated fossil beetle assemblages from late‐glacial sites in the Maritimes Region of eastern Canada. Fossil‐bearing sediments date from 12700 14C yr BP (14950 cal yr BP) to younger than 10800 14C yr BP (12730 cal yr BP), spanning a period which includes stratigraphic, palynological, chironomid and coleopteran evidence for a climatic deterioration during the Younger Dryas in North America. Mutual Climatic Range data suggest several ‘events’ in the coleopteran record from the Maritimes that appear similar to climate events recorded in the GRIP ice‐core record, including the (Younger Dryas) cooling event from GI‐1a to GS‐1 beginning c. 12650 GRIP yr BP Some of the major temperature oscillations of Greenland Interstadial 1 may also be reflected in the coleopteran record of the Maritimes.
Palaeoenvironmental reconstruction of a glaciotectonized Early and Middle Pleistocene land surface, palaeosol and river sediments: Great Sampford, Suffolk, England
Authors: READ GLYNIS , ROSE JAMES , KEMP ROB A.
Published: July 2010

Glaciotectonized sediments and palaeosol at Great Sampford, western Suffolk, England are reconstructed to their original positions in order to determine the form of the original land surface and the associated soil development. The restored stratigraphy consists of Early Pleistocene Kesgrave Sands and Gravels which were deposited by the ‘pre‐glacial’ river Thames, with the Early–Middle Pleistocene Valley Farm Soil developed on a terrace surface. These units are overlain by Sampford Deformation Till and Lowestoft Till, which were formed during the Middle Pleistocene Anglian glaciation. The micromorphological features of the reconstructed soil are interpreted in terms of three climatic cycles, each comprising a period of temperate climate soil formation followed by cold climate soil disruption. The final stage of disruption is associated with the periglacial climate that preceded Anglian glacierization. This pedological reconstruction is the most complex yet recognized from British Early and Middle Pleistocene palaeosols and provides an insight into major climatic oscillations prior to the Anglian Glaciation. The surface upon which the soil developed is one of the oldest terraces of the ‘pre‐glacial’ River Thames that were formed when this river flowed northwards through East Anglia.
Recent shallow marine ostracods from high latitudes: implications for late Pliocene and Quaternary palaeoclimatology
Authors: BROUWERS ELISABETH M. , CRONIN THOMAS M. , HORNE DAVID J. , LORD ALAN R.
Published: July 2010

New information about modern high‐latitude marine ostracod faunas and about their occurrence in late Pliocene and Quaternary sequences promotes the application of these microfossils to palaeoenvironmental, palaeo‐biogeographical and palaeoclimatological problems. Five poorly known species (Cluthia cluthae, Finmarchinella logani, Roundstonia globulifera, Roundstonia macchesneyi and Semicytherura complanata) from North Atlantic, North Pacific and Arctic areas are confirmed as extant and are used to demonstrate the potential of marine ostracods as tools for palaeoclimate studies. The genus Bonnyannella Athersuch, 1982 is shown to be a junior synonym of Roundstonia Neale, 1973.
Carbonate dispersal trains, secondary till plumes, and ice streams in the west Foxe Sector, Laurentide Ice Sheet
Authors: DREDGE LYNDA A.
Published: July 2010

Regional carbonate dispersal trains cross Melville Peninsula in the northeastern Canadian Arctic. These trains are 50–125 km across and 100–300 km long. The northern dispersal train crosses upland and lowland areas, while the Rae Isthmus train follows the lowlands. The distribution of carbonate in boulder, pebble and matrix till fractions indicates long‐distance glacial transport of limestone, a low rate of dilution, and comminution from pebble to silt sizes. Dispersal patterns and geotechnical properties of the till suggest deforming bed and basal gliding mechanisms of ice flow associated with ice‐streaming. Regional ice streams may have been ‘normative’ in carbonate terrain during the main Foxe (Wisconsin) Glaciation. Till plumes within regional dispersal trains, showing little dilution of carbonate down‐ice from bedrock sources, are oriented towards lowlands. These features, sharp‐edged and 300 mwide, mark zones of augmented flow. They are late‐glacial features that formed after calving bays developed in Committee Bay. The dimensions of the dispersal trains, and ice‐flow styles and mechanisms, are similar to those of modern Antarctic ice streams. The sharp edges of till plumes may delineate flow boundaries marked by lateral crevasse zones in the late‐glacial ice sheet. Secondary streams‐within‐ice streams have not been reported previously in the literature.
10Be dating of Younger Dryas Salpausselkä I formation in Finland
Authors: TSCHUDI SILVIO , IVY‐OCHS SUSAN , SCHLÜCHTER CHRISTIAN , KUBIK PETER , RAINIO HEIKKI
Published: July 2010

Boulders of the Younger Dryas Salpausselkä I (Ss I) formation west of Lahti, southern Finland, were sampled for surface exposure dating. The 10Be concentrations, determined by accelerator mass spectrometry, yield minimum exposure ages of 11 930 ± 950, 11 220 ± 890, 11 050 ± 910 and 11 540 ± 990 years, using recently published production rates scaled for latitude and elevation. This includes a correction to the production rate resulting from postglacial uplift of the Fennoscandian lithosphere (i.e. changing elevation) during the time of exposure. The error‐weighted mean exposure age of 11 420 ± 470 years of the analysed boulders agrees with previous varve dates of Ss I, which range from 11 680 to 11 430 calendar years BP. However, erosion has to be taken into account as a process affecting rock surfaces and therefore influencing exposure ages. Available information suggests an erosion rate of 5 mm/kyr, which increases the error‐weighted mean exposure age to a value of 11 610 ± 470 years. Within the errors, the formation of Ss I in the Vesala area west of Lahti falls into the Younger Dryas time bracket, as defined by the GRIP and GISP 2 ice core (Greenland).
Submarine and onshore end moraines in southern Newfoundland: implications for the history of late Wisconsinan ice retreat
Authors: SHAW JOHN , GRANT DOUGLAS R. , GUILBAULT JEAN‐PIERRE , ANDERSON THANE W. , PARROTT D. RUSSELL
Published: July 2010

Recessional positions of the Newfoundland ice sheet 14–9 ka BP are represented by fjord‐mouth submarine moraines, fjord‐head emerged ice‐contact marine deltas, and inland moraine belts. The arcuate submarine moraines have steep frontal ramparts and comprise up to 80 m of acoustically incoherent ice‐contact sediment (or till) interfingered distally with glaciomarine sediment that began to be deposited c. 14.2 ka BP. The moraines formed by stabilization of ice that calved rapidly back along troughs on the continental shelf. The ice front retreated to fjord‐heads and stabilized to form ice‐contact delta terraces declining in elevation westward from +26 m to just below present sea level. Stratified glaciomarine sediments accumulated in fjords, while currents outside fjords eroded the upper part of the glaciomarine deposits, forming an unconformity bracketed by dates of 12.8 and 8.5 ka BP. The delta terraces are broadly correlated with the 12.7 ka BP Robinson's Head readvance west of the area. The ice front retreated inland, pausing three or four times to form lines of small bouldery stillstand moraines, heads of outwash, sidehill meltwater channels, and beaded eskers. Lake‐sediment cores across this belt yield dated pollen evidence of three climatic reversals to which the moraines are equated: the Killarney Oscillation c. 11.2 ka BP, the Younger Dryas chronozone 11.0–10.4 ka BP, and an unnamed cold event c. 9.7 ka BP. Relative sea level fell in the early Holocene because of crustal rebound, so that out‐wash and other alluvium accumulated in deltas now submerged due to relative sea‐level rise.
Lateglacial varve chronology and biostratigraphy of lakes Holzmaar and Meerfelder Maar, Germany
Authors: BRAUER ACHIM , LITT THOMAS , NEGENDANK JÖRG F. W. , ZOLITSCHKA BERND
Published: July 2010

In this paper we briefly compare previously published data on four lateglacial sediment profiles from lakes Holzmaar and Meerfelder Maar in the Eifel region. Two of these profiles (one from each lake) are varve‐dated, whereas the other two pollen profiles are on depth scales. In general, the palynological signal in all profiles compares well, proving the regional validity of the individual data sets. There are some discrepancies between Holzmaar and Meerfelder Maar, however, mainly concerning varve dating of major lateglacial features, and these are explained after detailed correlation using a combination of varve dating and palynological signals. The result is a consistent varve‐dated biostratigraphy for the Lateglacial in the Eifel region. Moreover, it is demonstrated that a combination of varve chronology and high resolution palynostratigraphy in several lake profiles enables even gaps of a few decades up to a few centuries to be detected, thus providing a valuable tool for precise regional palaeoenvironmental study. This multi‐core study on two lakes from the same region demonstrates the likelihood of undetected errors in single‐core studies on non‐varved sediments.
On the early history of the wild reindeer (Rangifer tarandusL.) in Finland
Authors: RANKAMA TUIJA , UKKONEN PIRKKO
Published: July 2010

This paper discusses the early migration of the wild reindeer into Finland. Reindeer bones found in dated archaeological contexts suggest that the two subspecies, the mountain reindeer (Rangifer tarandus tarandusL.) and the forest reindeer (Rangifer tarandus fennicusLönnb.), were part of our fauna as early asc.9000 BP and 7000 BP, respectively. The mountain reindeer may be descended from the European Pleistocene reindeer, and may have migrated into northern Finland via the west coast of Norway. The forest reindeer invaded Finland directly from the east, from its glacial refugia in Siberia. During the Holocene, the distribution ranges of these two subspecies fluctuated in accordance with climatic and vegetational changes in northern Finland.
Late Quaternary history around Nioghalvfjerdsfjorden and Jøkelbugten, North‐East Greenland
Authors: BENNIKE OLE , WEIDICK ANKER
Published: July 2010

Nioghalvfjerdsfjorden in North‐East Greenland is at present covered by a floating glacier. Raised marine deposits in the surrounding area contain shells of marine molluscs, bones of marine mammals and pieces of driftwood. A fairly systematic sampling of such material has been conducted, followed by extensive radiocarbon dating. We suggest that the Greenland ice sheet extended onto the shelf offshore North‐East Greenland during isotope stage 2, perhaps even reaching the shelf break. During the subsequent recession of the ice sheet, the entrance of Nioghalvfjerdsfjorden had become ice‐free by 9.7 cal. ka BP. The recession culminated between 7.7 and 4.5 cal. ka BP, during which time the fjord was glacier‐free along its entire 80 km length. No dates younger than 4.5 cal. ka BP are available on marine material from the fjord, and it seems probable that the fjord has been continuously covered by the floating glacier since this time. The maximum glaciation was attained around AD 1900, after which thinning and recession took place. The marine limit increases fromc.40 m above sea level near the present margin of the Inland Ice toc.65 m above sea level at the outer coast. These figures fit into the regional pattern of the marine limit for areas both to the south and north. The marine fauna comprise two bivalves,Macoma calcareaandSerripes groenlandicus, that may represent a southern element present during the Holocene temperature optimum. Remains of three taxa of southern extralimital terrestrial and limnic plants were dated to 5.1 cal. ka BP, and remains of another extralimital plant were dated to 8.8 and 8.5 cal. ka BP. The known Holocene time ranges of the willowSalix arcticaand the lemmingDicrostonyx torquatushave been extended back to 8.8 and 6.4 cal. ka BP, respectively, providing minimum dates for their immigration to Greenland.
Glacial deposits and Late Weichselian ice‐sheet dynamics in the northeastern Baltic Sea
Authors: NOORMETS RIKO , FLODÉN TOM
Published: July 2010

Glacial deposits and landforms, interpreted from the continuous seismic reflection data, have been used to reconstruct the Late Weichselian ice‐sheet dynamics and the sedimentary environments in the northeastern Baltic Sea. The bedrock geology and topography played an important role in the glacial dynamics and subglacial meltwater drainage in the area. Drumlins suggest a south‐southeasterly flow direction of the last ice sheet on the Ordovician Plateau. Eskers demonstrate that subglacial meltwater flow was focused mostly within bedrock valleys. The eskers have locally been overlain by a thin layer of till. Thick proximal outwash deposits occupy elongated depressions in the substratum, which often occur along the sides of esker ridges. Ice‐marginal grounding‐line deposit in the southern part of the area has a continuation on the adjacent Island of Saaremaa. Therefore, we assume that its formation took place during Palivere Stadial of the last deglaciation, whereas the moraine bank extending southwestward from the Serve Peninsula is tentatively correlated with the Pandivere Stadial. The wedge‐shaped ice‐marginal grounding‐line deposit was locally fed by subglacial meltwater streams during a standstill or slight readvance of the ice margin. The thickness of the glacier at the grounding‐line was estimated to reach approximately 180 m. In the western part of the area, terrace‐like morphology of the ice‐marginal deposit and series of small retreat moraines 10–20 km north of it suggest stepwise retreat of the ice margin. Therefore, a rather thin and mobile ice stream was probably covering the northeastern Baltic Sea during the last deglaciation.
Deglaciation and palaeoclimate of the Andfjord‐Vågsfjord area, North Norway
Authors: VORREN TORE O. , PLASSEN LIV
Published: July 2010

This paper reviews the deglaciation history and palaeoclimate from 22 to 9.5 14Cka BP in the Andfjord‐Vagsfjord area. Eight main glacial events are recorded: The Egga‐I (>22 14Cka BP), the Bjerka, the Egga‐II (>14.6 14Cka BP), the Flesen (14.5 14Cka BP), the D (13.8–13.2 14Cka BP), the Skarpnes (12.2 14Cka BP), the Tromsø–Lyngen (10.7–10.3 14C ka BP) and the Stordal (10.0–9.5 14Cka BP). Onset of the final deglaciation occurred about 14.6 14Cka BP. Most of the western part of the Fennoscandian and Barents Sea Ice Sheets receded from the outer continental shelf 15–14 14Cka BP. The delivery and melting of icebergs at this time to the Norwegian‐Greenland Sea resulted in a low oxygen isotope event recorded in a number of cores in the region. Atlantic water intruded the area 13.2 14Cka BP, and an atmospheric warming commenced 12.9/12.8 14Cka BP. A marked glacial recession occurred before the Skarpnes event. During Allerød time, the glaciers retreated to the fjord heads or even farther inland. The Fennoscandian outlet glaciers readvanced (locally more than 40 km), reached their Younger Dryas outer limit after 10.7 14Cka BP and retreated from this position before about 10.3 14Cka BP.