bluuebunny/crossref_metadata_2025 huggingface dataset:
The Late Quaternary Skagerrak and its depositional environment
Authors: THIEDE JÖRN
Published: July 2010

The Skagerrak is a key region for our understanding of the Late Quaternary history of the East North Sea, of the entire Baltic basin and of the adjacent Scandinavian land areas. The depositional history of the postglacial Skagerrak began after the ice margin withdrew from Jutland to close to the modern Norwegian coast around 14 ka B.P. to 13 ka B.P. The Skagerrak was immediately filled by marine waters from the Norwegian Sea, but retained a fjord‐like shape until approximately 10.2 ka B.P., when a connection opened across central Sweden to the Baltic Ice Lake. This seaway closed around 9 ka B.P., but a new seaway to the Baltic basin opened subsequently (probably close to 8.5 ka B.P.) through the Danish Belts. At about 10 ka B.P. the Skagerrak ‘fjord’ also started to change shape due to the flooding of the large former land area under the modern North Sea. Paleo‐geography and ‐bathymetry of these changes can now be quantified in great detail. The young Quaternary sediments of the Skagerrak consist of fine‐grained clays with minor amounts of silty and sandy material and are mostly of terrigenous origin, whereas biogenic components in general make up only a minor proportion of the bulk sediment. Prior to 10 ka B.P. a major portion of these deposits originated from the Fennoscandian regions N and E of the Skagerrak, while ice‐rafting contributed coarse terrigenous components to the usually fine‐grained sediments and while it was filled by brackish surface and cold polar bottom waters. At approximately 10 ka B.P., more temperate waters started to fill the Skagerrak and a good portion of the sediment seems to have originated from areas to the South. The Norwegian Coastal Current can only be documented for the past 7 ka; subtle changes of the pelagic and benthic environments could also be documented for later intervals.
Sequences of Holocene forest history in the Scandes, inferred from megafossil Pinus sylvestris
Authors: KULLMAN LEIF
Published: July 2010

Kullman, Leif 1987 03 01: Sequences of Holocene forest history in the Scandes, inferred from megafossil Pinus sylvestris. Boreas, Vol. 16, pp. 21–26. Oslo. ISSN 0300–9483.

Altogether 54 14C‐datings of megafossil Pinus sylvestris L. from above the present tree‐limit in the southern Swedish Scandes were evaluated. The samples were discussed in relation to the present‐day tree‐limit of pine. Pine reached almost 200 m higher than at present shortly after deglaciation and remained at very high altitudes until at least 4,000–3,500 14C years B.P. The conclusion was that the precise biological and climatological interpretation of these regionally sampled data is still obscure. It is impossible to judge whether clusters of megafossil pine represent periods relatively favourable for pine growth and reproduction or merely periods advantageous for production of dead wood and its long‐term preservation. In terms of climate, these alternatives reasonably implicate widely different conditions.
Quantitative forest‐composition sensing characteristics of pollen samples from Swedish lakes
Authors: PRENTICE I. COLIN , BERGLUND BJÖRN E. , OLSSON TOMMY
Published: July 2010

Prentice, I. Colin, Berglund, Björn E. & Olsson, Tommy 1987 03 01: Quantitative forest‐composition sensing characteristics of pollen samples from Swedish lakes. Boreas, Vol. 16, pp. 43–54. Oslo. ISSN 0300–9483.

Surface pollen percentages of major tree genera in 53 moderate‐sized lakes in south and central Sweden were compared with percentages of mean forest volume derived from survey plots within 5, 10, 20, 50 and 100 km of each lake. A maximum likelihood extended R‐value method was used to estimate relative slopes and intercepts of the pollen‐tree relationship at each forest sampling radius. Slopes generally went up and intercepts down as sampling radius was increased. Visual goodness‐of‐fit was optimal at 5–10 km for Picea and at 50–100 km for Pinus, consistent with theoretical pollen source areas. Fagus gave good visual fits at all radii, but Quercus gave indifferent fits and Betula and Alnus poor fits. The taxa differed in relative pollen representation, with relative R‐values on the order of 0.11 for Picea, 0.90 for Fagus, 1.0 for Pinus, 1.5 for Quercus, 2.3 for Alnus and 2.5 for Betula. Regional forest patterns can be reconstructed from lake pollen spectra by applying R‐values, but the ‘region’ represented depends on each taxon's pollen dispersal characteristics and spatial pattern. The R‐values given here could be used to calibrate European Holocene pollen spectra from moderate‐sized lakes for long‐term forest dynamic mapping.
Deluge II and the continent of doom: rising sea level and collapsing Antarctic ice
Authors: HUGHES TERENCE J.
Published: July 2010

Hughes, Terence J. 1987 06 01: Deluge II and the continent of doom: rising sea level and collapsing Antarctic ice. Boreas, Vol. 16, pp. 89–100. Oslo. ISSN 0300–9483.

Many cultures in both the Old and New Worlds have preserved legends of a Great Flood. In the Biblical deluge, ‘the springs of the great deep broke through and the sluices of heaven opened’ (Genesis 7: 11). The rise in sea level, as opposed to prolonged rainfall, is a conceivable cause of global flooding because the last stages in collapse of late Wisconsin/Weichselian ice sheets occurred in the late prehistorical period, from 8,000 to 6,000 B.C. A possible mechanism that might collapse large parts of ice sheets in a short time is found in Jakobshavns Isbrae, which drains the west‐central part of the Greenland Ice Sheet. This mechanism, called the Jakobshavns Effect, is described and its possible role in Holocene collapse of former Northern Hemisphere ice sheets (Deluge I) and future collapse of parts of the Antarctic Ice Sheet (Deluge II) is examined. Rapid global flooding by this mechanism is extremely unlikely; however, we lack the information needed to eliminate the possibility.
Stratigraphic potential of amino acid ratios in Pleistocene terrestrial gastropods: an example from West‐Central Indiana, USA
Authors: MILLER BARRY B. , McCOY WILLIAM D. , BLEUER NED K.
Published: July 2010

Miller, Barry B., McCoy, William D. & Bleuer, Ned K. 1987 06 01: Stratigraphic potential of amino acid ratios in Pleistocene terrestrial gastropods: an example frpm West‐Central Indiana, USA. Boreas, Vol. 16, pp. 133–138. Oslo. ISSN 0300–9483.

The terrestrial gastropods Catinella spp., Stenotrema leai and Hendersonia occulta have been studied from 10 Wisconsinan and pre‐Wisconsinan sites in west‐central Indiana to determine if amino acid racemization values from these fossils would have stratigraphic utility in this area. The ages of the samples range from about 20,000 years B.P. for materials collected from radiocarbon‐dated deposits of the Trafalgar Formation, to >730,000 years B.P. for fossils obtained from magnetically reversed silts of the Jessup and Banner Formations. The shell samples have yielded four groups or aminozones based on the ratio of D‐alloisoleucine to L‐isoleucine in both the free fraction and the total acid hydrolysate from the shell samples. The results of this preliminary study appear to be consistent with the previously assumed age of the strata from which the fossils were collected and suggest that the technique has great promise as a chronostratigraphic tool in Quaternary sequences that contain terrestrial pulmonate and prosobranch gastropods.
The internal structure of glacial landforms: an example from the Halton till plain, Scarborough Bluffs, Ontario
Authors: SHARPE DAVID R.
Published: July 2010

Current views on the internal structure of many glacial landforms need further definition. For example, drumlinized Halton till plain near the Scarborough Bluffs, Ontario would traditionally be. viewed as a lodgement till sheet, but it was found to consist of complex sedimentary assemblages including sediment flows, melt‐out, deformation and lodgement tills. These facies vary spatially depending on whether deposition occurred beneath grounded ice or within subglacial cavities. Proglacial sediments bury portions of the till plain. Surface Rutings and drumlins clearly indicate the action of subglacial processes on the surface of Halton drift. Sedimentary structures at the contact between stratified sediments and diamictons within the Late Wisconsinan Halton drift are similar to those in older beds exposed at Scarborough Bluffs. The demonstration of the role of grounded ice in Halton drift and the similarity of sedimentary structures to those of the underlying Thorncliffe and Sunnybrook sediments suggests that the action of grounded ice cannot be ruled out in the case of the lower beds, as has been done by Eyles & Eyles (Geology 11, 146–152, 1983). Thus, surface Halton drift may be a model for recognition of similar environments of deposition in older beds beneath Halton. This analysis indicates flaws in a recent re‐evaluation of Scarborough Bluffs sediment interpreted as solely lacustrine and not directly affected by glaciers.
The last deglaciation (20,000 to 11,000 B. P.) on Andoya, northern Norway
Authors: VORREN TORE O. , VORREN KARL‐DAG , ALM TORBJØRN , GULLIKSEN STEINAR , LØVLIE REIDAR
Published: July 2010

Cores representing a 5.5m long sequence recovered from lake Æråsvatnet have been investigated for lithostratigraphy, micro‐ and macrofossils and radiocarbon chronology. For the first time in Fennoscandia the maximum Weichselian advance has been closely bracketed with radiocarbon datings (19,000–18,500 B.P.). A continuous stratigraphy from 18,500 B.P. and onwards, partly marine and partly lacustrine, discloses the local shoreline displacement, the palaeovegetation, the palaeoclimate and, together with other data, the deglaciation history. Two phases with a prevailing High Arctic climate have occurred: 18,000 to 16,000 B.P. and 13,700 to 12,800 B.P. Important climatic amelioration accelerating the deglacial recession occurred 16,000, 12,800 and 12,000 B.P. The continental ice sheet was situated close to its maximum position until about 16,000 B.P. The following deglaciation was interrupted by (a minor ?) readvance/halt about 15,000 B.P. (the Flesen event), 13,700‐13,000 B.P. (the D‐event), 12,500 B.P. (the Skarpnes event) and 11,000–10,000 B.P. (the TromsØ‐Lyngen event). The deglaciation chronology and pattern can be correlated with the suggested deep‐sea‐stratigraphy‐based stepwise pattern relying on the old age alternative for termination IA.
Bog development and environmental conditions as shown by the stratigraphy of Store Mosse mire in southern Sweden
Authors: SVENSSON GÖRAN
Published: July 2010

Macrofossil analyses, pollen analyses, and 14C datings were carried out on profiles from a bog complex in southern Sweden. The development started with a Carex fen c. 6,000 B. P. which transformed to bog c. 1,000 years later. The bog has developed through three stages separated by highly humified peat layers, recurrence surfaces, 3 and 2m below the present bog surface, and formed c. 2,500 and 1,200 B. P., respectively. The fen formation and the initiation of the last two bog stages were contemporaneous with high water levels in lakes of the region. The transition to bog and the formation of the two highly humified peat layers may be related to low water levels in lakes. It is probable that changes in the development of the mire were caused by the climate, since varying water levels are thought to be dependent on variations in the climate.
Palynology in a polar desert, eastern North Greenland
Authors: FUNDER SVEND , ABRAHAMSEN NIELS
Published: July 2010

A pollen diagram from a lake in a polar desert in eastern North Greenland records the regional vegetation history back toc.7,000 years calBP (6,000 years convBP) in this extreme environment, which presents the coldest thermal regime where vascular plants can grow. The diagram shows that polar desert developed from sparse high arctic tundra atc.4,300 years calBP (3,900 years convBP), owing to reduced summer heat. Also adjacent parts of high arctic Greenland, Canada and Svalbard suffered environmental decline, and polar deserts ‐ presently restricted to a narrow fringe of land at the shores of the Arctic Ocean ‐ were even more restricted before this time. Like other arctic vegetation types, polar desert is highly sensitive to summer temperatures, and its southern limit coincides with the isotherm for mean July temperatures of 3.5d̀C. A comparison with the Northwest European ice‐age pollen record shows no evidence of summers as cold as those now prevailing in the extreme north, and the results support the contention that the present Arctic and the ice‐age mid‐latitude environments are not identical.
Palaeomagnetic records from two varved clay sequences in the Middle Swedish ice marginal zone
Authors: SANDGREN PER , BJÖRCK SVANTE , BRUNNBERG LARS , KRISTIANSSON JAN
Published: July 2010

Two varved clay sequences, at Rystad and Tottnäs, situated in the Middle Swedish ice marginal zone were analysed palaeomagnetically. Two parallel profiles were sampled and analysed at each site. The varved clay at Rystad was dated by floating varve chronology. The varves at Tottnäs can be linked to Swedish time scale, expressed in calendar years B.P. Due to the distance between the sites they cannot be correlated by means of varve diagrams. Palaemagnetic methods were used as an alternative. Based an AF demanetization of pilot samples, the palaeomanetic to be too low, in the order of15d̀, compared to the site latitude. At Tottnäs the inclination records are very close to the expected inclination with respect to the site latitude. Because of a systematic inclination error in the Rystad profiles the correlation was based on the declination records. Statistical comparisons of these records between the two sites indicate that the sediment successions are partly synchronous. It is concluded that the deglaciation at Tottnäs started c. 130 years earlier than at Rystad. This mean that the Swedish ice marginal zone east of Rystad will have a more northeasterly extension than previously thought.
The age of Upper Pleistocene marine deposits of the Boreal transgression on the basis of electron‐spin‐resonance (ESR) dating of subfossil mollusc shells
Authors: MOLODKOV ANATOLY , RAUKAS ANTO
Published: July 2010

The potential use of a new ESR method for the dating of subfossil shells is discussed on an example from the northern part of the East‐European Plain. A variant of the ESR technique, elaborated at the Institute of Geology of the Academy of Sciences of the Estonian SSR, is described and the Eemian age of the Boreal transgression proved.
Glaciofluvial channels formed prior to the last deglaciation: examples from Swedish Lapland
Authors: RODHE LARS
Published: July 2010

At four localities in area east of the Sarek and Kebnekajse massifs in Swedish Lapland, glaciofluvial channels seem to have been overhidden by glaciers without having extensively modified. It is suggested that the channels were formed during an Early Weichselian stade. The last glaical advance had little effect on the pre‐exiting landforms at these localities and probably also at many other places in the area. Earlier theories about glacial development and deglaciation patterns in this area are based on morphology and the assumption that the landforms were formed during the last deglaciation. These theories need to be revised.
Deglaciation pattern and ice‐dammed lakes along the Saariselkä mountain range in northeastern Finland
Authors: JOHANSSON PETER
Published: July 2010

Traces of ice‐dammed lakes are found along the southern part of the Saariselkä mountain range. Various shore marks, outlet channels and fine‐grained sediments are indications of open water. The shallow basins were more or less filled by dead ice. At the beginning of deglaciation the meltwaters discharged over the mountain ridge to the north. As the ice margin receded toward the southwest new outlets were opened and the meltwaters discharged to the east and southeast. The ice‐dammed lakes existed and the deglaciation took place during the period 9,500‐9,300 B.P. The annual rate of retreat of the ice margin averaged 130–170 m per year.
Quaternary vertebrates in Hungary
Authors: KURTÉN BJÖRN
Published: July 2010

Book reviewed in this article:

Janossy, D. 1986: Pleistocene Vertebrate Faunas in Hungary.
The mechanized ‘Gik’ corer: seven years of use and improvement
Authors: VISSET LIONEL , HAURAY GERARD
Published: July 2010

Since 1980 the authors have been using a mechanized Gik corer for coring in marshlands and peat bogs. Final modifications to the equipment are described and shown in photographs and drawings.
Amino acid geochronology of selected interglacial sites in the North Sea area.
Authors: KNUDSEN KAREN LUISE , SEJRUP HANS PETTER
Published: July 2010

Isoleucine epimerization (alle/Ile) ratios have been measured on foraminiferal tests from interglaical sites in the southern North Sea region. In order to evaluate the possibilities of this amino acid method on benthic foraminifera, sites were chosen from areas where the stratigraphy was already well known. The study demonstrates that the isoleucine epimerization reaction in benthic foraminifera can be used for correlation and as a means of relative age estimation within a limited geographic area. Previous suggestions of a Holsteinian age for the Rugȧrd, Tornskov, and Wacken sites are supported for the Kås Hoved site. The age of most presumed Eemian sites is supported by the amino acid results; the Reighton site also seems to belong in this interglacial.
Reconstruction of Late‐Glacial lake‐level fluctuations in The Netherlands based on palaeobotanical analyses, geochemical results and pollen‐density data
Authors: BOHNCKE SJOERD , WIJMSTRA LEX
Published: July 2010

The Late‐Glacial infills of three lake successions in The Netherlands have been analysed for their palaeobotanical content (pollen, macroremains) as well as for their physical and chemical characteristics. The macro‐botanical analysis in association with the pollen analysis permitted the reconstruction of relative lake level fluctuations for each lake. There appeared to be good agreement between the three lake successions. Supporting evidence for the presence of alternating dry and wet phases was found in the geochemical results. The termination of the Bölling biozone coincides with a lowering of the lake levels that persisted throughout the Older Dryas. Water levels restore at the beginning of the Allerod biozone. Several fluctuations are recognized during the Allerod. The end of the Alleröd is characterized by a second major lowering in the lake levels, leading to an interruption in the sedimentation in cores from the fringe zone. Water depth increases at the beginning of the Younger Dryas biozone. A third major minimum in the lake levels is reached towards the end of the Younger Dryas biozone, probably explaining the recurrent hiatus at the transition to the Holocene record. Pollen concentration data in association with chronostratigraphical data provided the construction of sedimentation rate curves. Minima in these sedimentation rate curves appeared to correlate with periods of low lake level. The loss on ignition curve in association with the sedimentation rate data allowed an approximation of the organic production of the lakes involved. It revealed that the darker appearance of the Allerödin the lithologycan be ascribed mainly to a retardationin the sedimentation rate and not to a major increase in the organic production of the lakes.
Composition and source of the clay‐sized fraction of Saalian till in The Netherlands
Authors: HALDORSEN SYLVI , JØRGENSEN PER , RAPPOL MARTIN , RIEZEBOS PETER A.
Published: July 2010

The clay mineral composition of a number of Saalian till samples from The Netherlands shows a large variation in smectite and illite abundances. The samples were selected according to their source area, as inferred from coarse erratic components. Specimens containing primarily rock fragments indicative of East and East‐Central Baltic areas are associated with no or low smectite percentages in their clay fractions. Those with mainly flint and rock fragments indicative of the West Baltic areas have high smectite contents in the clay. In general the smectite‐rich material is found in the lower portions of the Saalian till bed, whereas the smectite‐poor occurs in the upper portions. The linkage between very fine and coarse till components in the upper smectite‐free parts of the till suggests that this entire till has been subjected to englacial transport over distances of at least 1000 km.
Basal till genesis in relation to bedrock morphology in the Berghem area, southwestern Sweden
Authors: RONNERT LARS
Published: July 2010

Investigations of Late Weichselian deposits on the plateau north of Berghem, southwestern Sweden, constitute the basis for a detailed interpretation of basal tills above the marine limit. Deposition in relation to bedrock ridges perpendicular to ice flow occurred mainly on the stoss side. The content of locally derived bedrock increases with depth and the intensity of deformation within the ridge increases whengoing from the ice‐proximal to the distal position. Drumlinoid features around a rock hillock suggest that the depositional behaviour on the stoss side was slightly different in the central part compared with the flanks. In the ice‐proximal position the earliest deposition occurred in the centre of the drumlinoid, where the frequency of locally derived components is highest. The deformation in the central part was more intense than on the flank. The details of the till stratigraphy and structures cannot be attributed to one single process. Rather, an interaction of processes is proposed to account for this deposition. The processes involved are lodgement, basal melt‐out, deformation and subglacial meltwater sedimentation.
Nature, origin and age of Holocene aeolian sand on Muckish Mountain, Co. Donegal, Ireland
Authors: WILSON PETER
Published: July 2010

Dissected sand sheets and flow‐aligned sand shadows occur near the summit of Muckish Mountain, Co. Donegal. The sand is of medium to fine size and moderately sorted to moderately well sorted. Sand transport by northerly winds is indicated by the location and morphology of the deposits. The source of the sand is a series of friable quartzite beds immediately below the northern edge of the summit plateau. Minor additions of gravel and very coarse sand, derived from the disintegration of plateau clasts, were probably also incorporated within the deposits by aeolian action, although surface wash associated with heavy rain or snowmelt may have mobilized these particles. The absence of diagnostic aeolian transport textures on quartz grain surfaces reflects the short distance/duration of transport. 14C dates indicate two phases of sand sheet accumulation: one between c. 5,300 ande. 2,650 B.P. and again after c. 1,910–1,760B.P. The sand shadows have formed within the last hundred years in response to the construction of small cairns across the plateau. Sand sheet dissection suggests erosion is currently occurring, but this began prior to the late nineteenth century. Present‐day sand accumulation is also apparent from the widespread scatter of grains trapped by surface Vegetation. The sand represents the first recognition of aeolian deposition in the uplands of Ireland.
Long‐distance transported Pinus pollen as a possible chronostratigraphic marker in the Scottish early postglacial
Authors: TIPPING RICHARD M.
Published: July 2010

Peaks ofPinuspollen inseveraldetailed early postglacial (Flandrian) pollen diagrams from western Scotland are interpreted as the result of a change in the prevailing wind direction and intensity during climatic amelioration following the Loch Lomond Stadial (Younger Dryas). This origin implies a degree of syn‐chroneity in this palynological feature, which if proven would be valuable in the poorly dated early postglacial. The absence of this palynological feature at many sites may be the result of poor sampling or stratigraphic resolution.
Paleoclimatic implications of an early Holocene glacier advance on Disko Island, West Greenland
Authors: INGÓLFSSON ÓLAFUR , FRICH POVL , FUNDER SVEND , HUMLUM OLE
Published: July 2010

The paper describes studies of glacial deposits and raised beaches on the island of Disko. West Greenland. Two stades in the glacial history are defined, the Godhavn stade, which represents the last major glaciation on Disko, and the Disko stade, which defines a Preboreal readvance. During the Godhavn stade, only eastern and southern Disko were affected by the extended Inland Ice, while glaciation on western and northern Disko was local in character. In connection with the deglaciation, the sea transgressed to the marine limit at c. 9,250‐9,000 BP. Immediately before, tentatively culminating around 9,300 BP, a significant readvance of glaciers on eastern Disko occurred. The marine limit rises on a transect from northwest to southeast across Disko from 60 m a.s.l. to 90 m. The paper discusses changes in equilibrium line altitude (ELA) during the deglaciation, and explains the Disko stade readvance in terms of variations in upper‐air wind conditions.
Seasonal and annual variation of pollen content in the snow of a Canadian high Arctic ice cap
Authors: BOURGEOIS JOCELYNE C.
Published: July 2010

Seasonal and annual pollen deposition over an eight‐year period (1981‐89) in the snow layers of the Agassiz Ice Cap, Ellesmere Island, was investigated. The annual and seasonal layers were determined from the snow stratigraphy. Thirteen to thirty‐five kg were sampled for each layer. Most of the pollen grains deposited on the ice cap originate either from the high Arctic regional tundra, or from the boreal forest and low Arctic tundra over 1,000 km to the south. The regional pollen types show large variations throughout the year and the maximum concentration is normally found in the late summer‐early autumn snow. The exotic types usually show less seasonal variation, although with slight maximum in the spring or summer layers. The annual regional and exotic pollen influx to the ice cap can be highly variable. These variations are tentatively related to climatic parameters.
Palaeomagnetism of Pliocene‐Pleistocene sediments and lava flows on Tjörnes and Flatey, North Iceland
Authors: EIRÍKSSON JÓN , GUDMUNDSSON ANDRÉS I. , KRISTJÁNSSON LEÓ , GUNNARSSON KARL
Published: July 2010

Palaeomagnetic measurements have been carried out on lava flows and volcaniclastic sedimentary rocks of Upper Pliocene and Pleistocene age from sections on the Tjömes Peninsula and a core section from the island of Flatey off North Iceland. Earlier palaeomagnetic work in the area is reviewed, and new data on the stratigraphy of the Hoskuldsvik Group on Tjörnes are presented. A revised polarity column based on our resultsisset upfortheoutcropson Tjörnes, including twoadditionalnormalsubchronswithin the Matuyama. Our palaeomagnetic results indicate that the rocks penetrated by the Flatey drillhole accumulated during the Matuyama. Age estimates for the Upper Tjömes sequence are reviewed, and correlation alternatives indicate that the earliest glaciation of Tjörnes took place either at c.2 Ma or near the Gauss/Matuyama boundary at c. 2.5 Ma. Correlation of individual Matuyama subchrons remains uncertain. A comparison of the climatic evidence from the Tjörnes area with data on oxygen isotope and carbonate variations at DSDP site 552A is used to evaluate correlation alternatives.
Plio‐Pleistocene rodent biostratigraphy and palynology of the Bresse Basin, France and correlations within western Europe
Authors: CHALINE JEAN , FARJANEL GENEVIèVE
Published: July 2010

Five new palynological sequences in the Bresse valley (France), covering Reuverian, Praetiglian, Tiglian and Eburonian‐Waalian times, yielded rodent teeth of the Mimomys occitanus‐savini lineage evolving in Eurasia by phyletic gradualism. For the first time the west European palynological zonation is correlated with the Eurasiatic rodent one, leading to the following attributions: Mimomys occitanus: Reuverian; Mimomys polonicus: Praetiglian to early Tiglian; Mimomyspliocaenicus: Tiglian; Mimomys ostramosensis: Eburonian to early Waalian; Mimomys savini occurring from Waalian to Cromerian. As a result, the Neogene biozones MN15 to MN17 can be defined by nine new subdivisions.
Deglaciation chronology inferred from marine sediments in a proglacial lake basin, western Spitsbergen, Svalbard
Authors: Mangerund Jan , Svendsen John Inge
Published: July 2010

Sub‐bottom sediment profiles and sediment cores show that the lacustrine sediments in lake Linnevatnet are underlain by marine sediments and a basal till that mantles the bedrock. The till was probably deposited by the glacier that during the Late Weichselian glacial maximum removed all pre‐existing sediments from the basin. The cores were collected in closed basins, where continuous deposition is expected. The marine sediment in the studied cores is up to 8 m thick and consists of bioturbated clay and silt. Radiocarbon dates on shells from the base of the marine sequence suggest that glacial retreat from the lake basin occurred around 12,500BP. This is more than a thousand years older than basal shell dates from raised marine sediments on the slopes above the lake. Typical ice proximal litbofacies were not identified in the cores. stratigraphic record indicates both a rapid glacial retreat and that no younger glacial re‐advances occurred. During the Younger Dryas local glaciers on western Svalbard were smaller than during the Little Ice Age. This is in sharp contrast to western Europe, where Younger Dryas glaciers were much larger than those the Little Ice Age.
The Holocene glacial history of Lyngshalvöya, northern Norway: chronology and climatic implications
Authors: Ballantyne Colin K.
Published: July 2010

Up to four nested Neoglacial moraines occur in front of glaciers on Lyngshalvöya. Lichenometric measurements at 21 glaciers demonstrate that these represent five episodes of glacier expansion, one of which predated the Little Ice Age. Lichenometric, dendrochronological and historical evidence indicates that the oldest Little Ice Age moraines date to the mid‐18th century, and the youngest to A.D. 1910‐30. At nine small glaciers the A.D. 1910‐30 moraine represents the Neoglacial maximum; only larger glaciers were more extensive in the 18th century. It is inferred that conditions for glacier growth were less favourable in the 18th century than in A.D. 1880–1910 because of low winter snowfall. Comparison of the relative magnitude of 18th‐ and 20th‐century advances on Lyngshalvöya with those of southern Norway suggests that the diminished winter precipitation was due to the southerly location of the North Atlantic oceanic polar front in the 18th century, which resulted in a reduction in winter cyclonic activity in northern Scandinavia but in an increase in snowfall farther south.
Holocene climate as reflected by a malacological sequence at Verrières, France
Authors: LIMONDIN NICOLE , ROUSSEAU DENIS–DIDIER
Published: July 2010

Though numerous analyses have been made of Holocene pollen sequences, they come from similar environmental contexts, mainly peat deposits. Land snails can provide good palaeoecological and palaeoclimatical data in different drier environmental settings. The Verrières deposits, located in the Seine Valley, southeast of Paris, provide rich and abundant malacofaunas. We compare the well–defined local biostratigraphy with other mollusc stratigraphies from Burgundy, the closet site to the studied region. Multivariate analysis of the malacofaunas indicates that temperature and moisture did not always vary in parallel during the Holocene. On the other hand, Verrières malacofaunas reflect the main Holocene changes, as observed in the classical pollen series, confirming the reliability of the local biostratigraphy. The younger Dryas in Verrières was cold and cry. This was followed by the Preboreal phase, which is not well preserved at Verrières, but shows cool and humid conditions. The Boreal and Subboreal both show a cold and moist event bounded by two temperature phases. The Atlantic is also divided into two temperate phases by a cool and moist event. The Subatlantic shows temperature oscillations with cool peaks, but moisture shows a continuous trend to dryness.
Sedimentology and history of a Late Wisconsinan glacial lake, Grande Prairie, Alberta, Canada
Authors: LIVERMAN DAVID G. E.
Published: July 2010

The Grande Prairie region of northwestern Alberta was partially covered by glacial Lake Peace, which was dammed against the retreating Laurentide ice sheet. Two levels of glacial Lake Peace are identified in the study are by closely spaced groups of strandlines and minor deltas lying at 805 to 840 m a. s. l., and 655 to 710 m a.s.l. Sedimentation associated with the upper of the two lake levels is marked by rhythmites of silt and clay deposited by turbid underflow, interbedded with diamicton deposited by debris flow. Dropstones and dump structures indicate common ice‐rafting. Thick sequences are only found on the axes of major valleys, where sediment gravity flows were concertrated. Thin sequences of ice proximal glaciolacustrine sediments reflect topographic setting and do not indicate a short‐lived lake. Retreat of the ice front resulted in a decrease in ice‐rafted material and diamicton in sediments. The fall in lake level to the second stage resulted in deposition of sequences of vaguely laminated silt and clay close to the modern Beaverlodge River. These sediments were deposited by suspension settling from interflow or overflow of the Beaverlodge River as it entered the lake. Lake sedimentation was dominated by inflow from unglaciated areas, rather than the ice front.
Development of low–centred ice–wedge polygons in the northernmost Ungava Peninsual, Queébec, Canada
Authors: SEPPALA MATTI , GRAY JAMES , RICARD JEAN
Published: July 2010

Morphological and vegetation mapping and stratigraphic studies were carried out on a 60 by 250 m low–centered polygon field on a flood–plain of the Riviére Deception in the continuous permafrost zone of northernmost Ungava. Analyses of grain size, water and ice content, deformation structures, and macrorests were carried out on drill–core samples, up to a maximum depth of 3.19 m, and radiocarbon dates were obtained from several peat horizons. Five different vegetational habits were identified: uplifted banks, ice–wedge fissures, hummocky centres, wet polygon centres, and water ponds. The stratigraphic analyses revealed many sand layers and organic layers, alternating with a few layers of segregated ice. In the raises banks, brown fen peats represent former wet conditions prior to bank uplift. Total ice volumes of the core samples from polygon centres and banks averaged 60%, and were generally in the form of pore ice. Segregated ice was concentrated in ice wedges. The Low gradient of the polygon field and the shallow active layer are responsible for impded drainage. The origins of this isolated low–centred polygon field are discussed in terms of special local terrain conditions. River flooding since glacio–isostatic emergence at 6000 BP repeatedly spread alluvial sands onto the low flood–plain, which thus became progressively built up to its present elevation. Peat layers buried by these alluvial sands have permitted the changing local drainage conditions to be radiocarbon–dated for the last 2600 years for the core sites. Impeded drainage, low winter temperatures, probable thin snow cover, rapid sedimentation of flood–plain sands, and high volumetric ice contents have created the critical thermal regime necessary for repeated frost cracking in a polygonal pattern, with concomitant ice–wedge dev–elopment. Ice wedges developed at least as early as 2200 BP, causing the formation of low banks. Further growth of ice wedges deformed the peat and sand layers on the bank margins and led to the rise of the latter to heights of 0.5 to 1 m above the intervening low wet polygon centres. More water was then collected in the depressions, leading to a transformations of the vegetation cover from mossy heath to sphagnum bog, wet fen, sedge‐covered ponds, and eventually in some cases to open‐water pools. The stratigraphic evidence suggests that several generations of high banks formed and disappeared and that their position has changed. Deformation by continued ice–wedge growth has been insignificant since 1000 BP, However. A relatively thick surface peat layer also indicates that sand layers have not been contributed to the polygon field by flooding since ˜ 500 BP.
The glaciation of northeastern Kansas
Authors: ABER JAMES S.
Published: July 2010

The traditional pre‐Illinoian glacial stratigraphy in the central United States has been abandoned, which leaves a void in the Pleistocene stratigraphy of Kansas. The Independence Formation is proposed as a tithostratigraphic unit in northeastern Kansas. The Independence Formation consists of all diamictons and stratified sediments interbedded with diamictons. The Independence Formation vanes greatly in thickness and texture, but it always contains erratics derived from the Canadian Shield. At least two glacial advances took place in northeastern Kansas, first by the Minnesota lobe coming from the northeast, and later by the Dakota lobe from the northwest. During the first advance, glacial Lake Atchison was dammed in a now‐buried valley. Overflow from this lake cut spillways that form parts of the Blue, Kansas, and Missouri valleys. During the later ice advance, the Kansas valley was blocked, and temporary lakes formed, from which catastrophic flooding took place. The age of the Independence Formation is interpreted as 0.7 to 0.6 million years BP. It is considered equivalent in age and stratigraphic position to type A2 and A3 tills of Nebraska and western Iowa and to the McCredie Formation of northern Missouri. This age range corresponds to oxygen‐isotope stages W16.
Holocene development and early extreme acidification in a small hilltop lake in southern Finland
Authors: KORHOLA ATTE A. , TIKKANEN MATTI J.
Published: July 2010

The Holocene development of Pieni Majaslampi, a small hilltop lake which is exceptionally old for the conditions prevailing in southern Finland, is studied here by sedimentological and biostratigraphical methods. The lake is naturally acidic, with a pH of 4.5, and has been so since at least 8500 C14 BP, as determined from inferred‐pH techniques based on contemporary diatom‐pH relationships. The lake was found to have been subjected to extremely pronounced acidification during its early developmental stages, the pH having dropped from 5.8 to 4.7 between c. 10,000 and 8500 BP. Predicted pH values ranged from 4.5 to 5.1 over the remainder of its 8500‐year history. Low pH values of 4.5‐4.7 were found at the end of the Boreal Chronozone and in the Subboreal Chronozone and higher pH values of 4.7‐5.1 in the Atlantic and Subatlantic chronozones. This pattern is believed to reflect changes in macroclimate, particularly humidity. The rapid early acidification was shown in the cladoceran succession by the replacement of Bosmina longirostris by Bosmina (Eubosmina) longispina and by an increased number of species such as alonella nana and Alonella excisa. considerable shifts in diatom species composition and abundance were observed during the most recent times, but distributions indicate that all the abundant taxa most frequently occur under acidic conditions, suggesting that other factors in addition to pH may be responsible for the shifts.
Benthonic and planktonic foraminifera in relation to the Early Holocene stagnation in the Ionian Basin, Central Mediterranean
Authors: RASMUSSEN TINE LANDER
Published: July 2010

The distribution patterns of benthonic and planktonic foraminifera in cores from the Ionian Basin, central Mediterranean, were investigated in relation to the deposition of sapropel S‐1. The sapropel is a dark organic‐rich sediment deposited under anoxic conditions during the last marine stagnation in the Early Holocene. The major divisions between both benthonic and planktonic faunas correspond to changes in the core lithology and coincide with the transitions between pre‐sapropel, sapropel/‘oxidized layer’ and post‐sapropel sediments. The faunal evidence shows that the oxidized layer belongs to the sapropel sequence. The planktonic faunas have the same species composition as in the sapropel sediment and the high density of planktonic species continues into the oxidized layer. The oxidized layer is devoid of a benthonic fauna or contains a ‘sapropel‐associated’ fauna composed of infaunal species with an affinity to high supply of organic material material and low oxygen. High depletion in the heavy oxygen isotope in the oxidized layer substantiates the faunal evidence. A peak in abundance of the planktonic species Globorotalia inflata at the top of the oxidized layer marks the time when turnover of the water masses ended the stagnation phase and sapropel sedimentation in the Ionian Basin at about 6000 BP. The distribution of the benthonic and planktonic foraminifera shows that the sapropel in the central part of the Ionian Basin was originally almost twice as thick as it is today. When oxygen returned to the deep sediments the top of the sapropel was oxidized to 4–7 cm below its original surface. Only the lower part of the sapropel is preserved. The remainder is now a red laminated layer, the ‘oxidized layer’.
Late Glacial De Geer moraines with glaciofluvial sediment in the Chapais area, Québec (Canada)
Authors: BEAUDRY LUC M. , PRICHONNET GILBERT
Published: July 2010

Glaciofluvial De Geer moraines have rarely been described in detail in the literature. This study presents a model for the genesis of moraines of this type in the Chapais area, Québec. The model is based mainly on facies and deformatin structures analysis, and geomorphological data. Well‐stratified glaciofluvial material is commonly found in the core of the moraines, whereas till or glacial diamicton may be present as surficial cover on their proximal side or as injected lenses in the sorted sediments. The paleocurrents are systematically directd downglacier. The moraines were built up in subglacial crevasses in areas where meltwater was channelized. Water flowed under pressure from small upglacier cavities, carrying a load of coars‐grained material When flowing water entered crevasses already occupied by water, flow sparation occurred, reducing the capacity of the flow to carry the particles, and avalanching glaciofluvial material on the leeside of the piled sediments. The occurrence, in these sediments, of glaciotectonic deformation structures such as overturned to recumbent folds and thrust faults is evidence that the glacier was still active to some degree during and after the sedimentation phase.
Scanning electron microscopy of quartz grains in supraglacial debris, Adishy Glacier, Caucasus Mountains, USSR
Authors: MAHANEY WILLIAM C. , VAIKMAE REIN , VARES KAI
Published: July 2010

The surface microtopography of quartz grains in glacial depostis has often been attributed to mechanical release from source rocks during weathering and prior to entrainment by glaciers. Fractures on quartz particles, including subparallel and conchoidal features, often attributed to cryostatic pressure in ice and stick‐slip processes at the base of glaciers, have been considered, in part, to result from mechanical weathering of source rocks. To test this hypothesis we studied 15 samples of supraglacial debris from the Adishy Glacier in the central Caucasus Mountains, USSR. Clasts in transport on the surface of the glacier originate primarily from the cirque headwall by weathering and mass wasting processes; a minor amount is presumed to have been derived from aeolian influx following reworking of older sediments down valley. The results show unequivocally that mechanical weathering is only likely to produce grains with pronounced fracture faces that lack subparallel and conchoidal fracture features. No fresh glacial‐crushing type features were observed on these samples. Grains that had been glacially crushed, weathered and retransported, presumably by aeolian processes, were observed in four samples of the data set.
Terminal environment, topographic control and fluctuations of West Greenland glaciers
Authors: WARREN CHARLES R.
Published: July 2010

Glaciers are commonly regarded as sensitive indicators of climatic change, but iceberg calving can partially decouple glacier oscillations from climatic forcing. Recent fluctuations (1942–85) of 72 West Greenland outlet glaciers were studied using aerial photographs, and nine of them examined in the field. Despite similar climatic forcing, variable glacier behaviour is apparent. Eighty‐four percent of the land terminating glaciers have been retreating or stable during the period, whereas more than half the tidewater and lake terminating glaciers have been advancing. The calving glaciers exhibit much greater variability in frontal behaviour. Patterns of change suggest that the land‐terminating glaciers are controlled dominantly by variations in summer temperature, but that calving dynamics have caused the tidewater and lake‐calving glaciers to respond to climatic change in non‐linear ways. Dynamic and response contrasts are apparent between freshwater and tidewater glaciers. Trough geometry is of great significance in controlling the nature and magnitude of frontal change of calving glaciers; in particular, topographic ‘pinning points’ represent potentially stable locations within the fjord at which stillstands almost invariably occur, irrespective of climatic change or regional trends.
Lake Torfadalsvatn: a high resolution record of the North Atlantic ash zone I and the last glacial‐interglacial environmental changes in Iceland
Authors: BJÖRCK SVANTE , INGÓLFSSON ÓLAFUR , HAFLIDASON HAFLIDI , HALLSDÖTTIR MARGRÉT , ANDERSON N. JOHN
Published: July 2010

High resolution environmental records with a refined chronology are essential to understand, reconstruct and model the climate dynamics of the last glacial‐interglacial transition. Sediments from Lake Torfadalsvatn in northern Iceland contain at least four primary volcanic tephras that belong to ash zone I in the North Atlantic deep‐sea cores. We chemically define these basaltic/rhyolitic tephras and the high resolution allows us to date them to about 10,800, 10,600, 9300 and 8900 BP. This detailed tephrostratigraphy will act as a refined dating and correlation tool in the North Atlantic region and enable calibration between different absolute chronologies. The pollen stratigraphy of the sediments suggests that by 10,400 14C years BP plant colonization of coastal north Iceland had begun. The pollen stratigraphy shows a succession of pioneer plants, from open tundra vegetation towards birch‐juniper woodland, which probably also reflects a transition from a cool climate at 10,400 BP to conditions similar to today's sub‐polar oceanic climate around 9200 BP. Diatom data largely concur with the climatic information from pollen, indicating gradually increasing productivity in the lake.
Early Weichselian interstadial land biotas at Thule, Northwest Greenland
Authors: BENNIKE OLE , BÖCHER JENS
Published: July 2010

Allochthonous macroscopic plant and animal remains from a shallow‐water marine deposit from Northwest Greenland, assigned to the Early Weichselian/Wisconsinan, are indicative of arctic biotas dominated by herbaceous plants. The presence of several southern extralimital taxa show that summer temperatures were considerably higher than at present, presumably with a mean July temperature of about 8°C, as compared withc. 4°C at present.