bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Weichselian‐Holocene foraminiferal stratigraphy and palaeohydrogrphic changes in the Gothenburg area, southwestern Sweden
Authors: BERGSTEN HELENE , DENNEGARD BENNETH
Published: July 2010

Marine clay from two cores (50 and 36m deep) from Gothenburg, southwestern Sweden, have been analysed using different stratigraphic methods. Foraminiferal stratigraphy complemented withe lithostratigraphy, pollen and mollusc analyses show an environmental succession from arctic conditions with water depths up to 100m during Late Welchselian time, to a boreal shallow water environment in early Holocene time. A comparison of the foraminiferal faunas with those from corresponding investigations from southern Bohuslän, NW of Gothenburg, shows a similar development in the two areas. The sudden environmental change around the Pleistocene/Holocene boundary (10,000 years B.P.) along the Swadish west coast is attributed to changes of the hydrographic patterns; a general shift of the circulation pattern of the Skagerrak/ Kattegat at that time and or a large supply of fresh water flowing into the area from the Lake Vanern basin.
Periglacial phenomena in the wooded areas of Northern Sweden ‐ relicts from the Tärendö Interstadial
Authors: LAGERBÄCK ROBERT
Published: July 2010

Frost‐shattered bedrock and ventifacts interpreted to be abraded by drifting snow or ice particles occur frequently in the wooded areas of northernmost Sweden. Ice‐wedge casts and periglacial involutions are encountered more sporadically. The phenomena cannot be explained by the present or the Holocene climate and demonstrably pre‐date the last deglaciation. The relation to glacial and non‐glacial stratigraphy, and to ice flow during the latest glacial stade, strongly suggests that the periglacial activity dates from the local Tärendö Interstadial, tentatively correlated with Odderade. The presence of the periglacial features implies not only that different morphological formations survived the erosive impact of the last continental ice sheet but also that in wide areas the very ground surface, including ventifacts in primary position, is the same today as during the interstadial. A similar situation appears to prevail in northernmost Dalecarlia and parts of Härjedalen and Jämtland in central Sweden.
A Late Pleistocene sequence at Seitevare, Swedish Lapland
Authors: ROBERTSSON ANN‐MARIE , RODHE LARS
Published: July 2010

A peat layer beneath two till beds was found at Seitevare in Swedish Lapland. The pollen flora layer indicates deposition during the later part of the Eemian Interglacial. The vegetation consisted of open forests predominated by pine and birch, mixed with alder and spruce. The sedimentation took place in a small oligotrophic‐dystrophic water basin with a pH about 5, according to the diatom flora. In an adjacent section, silty sediments with pollen indicating interstadial vegetation (birches, herbs) are covered by one till bed. These sediments are tentatively correlated with the Peräpohjola Interstadial in northern Finland and north‐eastern Sweden. The lithostratigraphy indicates one pre‐Eemian and probably three Weichselian glacial advances.
A splendid book on the West Antarctic Ice Sheet
Authors: SUGDEN DAVID E.
Published: July 2010

Book reviewed in this article:

Van der Veen, C. J. & Oerlemans, J. (eds.) 1986: Dynamics of the West Antarctic Ice Sheet.
Younger Dryas‐Preboreal moraines and deglaciation in southwestern Värmland, Sweden
Authors: LUNDQVIST JAN
Published: July 2010

In an area in southwesternmost Värmland, western Sweden, ice‐marginal deposits have been mapped and studied. They can be correlated with the Norwegian Younger Dryas to Preboreal Ås, Ski and Aker ice‐marginal ridges, and with lines of ice recession earlier constructed in Dalsland. Together they give valuable information about the mode of deglaciation in southern Scandinavia. They indicate a pattern of deglaciation with intense upbreaking by calving of the ice eastwards from the Oslo Fjord and northwards in the Vänern basin. This process caused a downdraw of ice around the highland between those areas. Ice streams and, later, valley glaciers were formed in the large Årjäng‐Koppom and Glafsfjorden‐Byälven valleys. Between them a lobe‐shaped, stagnant ice cap was isolated from further supply from the main ice sheet in the north. This ice cap, here called the Dal lobe, wasted down with a complicated pattern from the west, south and east.
Deglaciation pattern indicated by the ice‐margin formations in Northern Karelia, eastern Finland
Authors: ERONEN MATTI , VESAJOKI HEIKKI
Published: July 2010

A map has been reconstructed representing the large‐scale glacial and glaciofluvial morphology of Northern Karelia and the adjacent area of Soviet Karelia. Observations have been made on the directions of glacial striae and on the distribution of sub‐aquatic and supra‐aquatic terrain in order to obtain a consistent picture of the course of deglaciation in the area and the factors affecting it. The map indicates that the behaviour of the glacier during the deglaciation was largely governed by the distribution of sub‐aquatic and supra‐aquatic areas. The marginal zone of the ice sheet was divided into two large lobes in this area. The Finnish Lake District Lobe terminated mostly in water, giving rise to massive glaciofluvial accumulations, while the North Karelian Lobe flowed on the land above the highest shore levels, pushing up several more or less discontinuous narrow end‐moraine ridges. Relatively large glaciofluvial deposits were also formed in the supra‐aquatic area in places where the ice margin terminated in a local ice‐dammed lake. It is evident that the Salpausselkä I and II end‐moraines extend as continuous formations only to the zone where the former ice margin rose onto dry land during the deglaciation phase. The spatial and temporal differences in the glacial dynamics and differing depositional environments gave rise to the complex glacial morphology of Northern Karelia.
Comparison of accelerator and radiometric radiocarbon measurements obtained from Late Devesian Lateglacial lake sediments from Llyn Gwernan, North Wales, UK
Authors: LOWE J. JOHN , LOWE STEPHEN , FOWLER ALISON J. , HEDGES ROBERT E. M. , AUSTIN TIM J. F.
Published: July 2010

Accelerator mass spectrometry measures of the radiocarbon activity of various chemical fractions prepared from Late Devensian Lateglacial lake sediments from the site of Llyn Gwernan, near Cader Idris, North Wales are presented and assessed. These are compared with radiocarbon measurements obtained by radiometric (decay) counting which were reported earlier from the same site and are considered in the light of pollen‐stratigraphic information. The potential advantages of accelerator radiocarbon measurements to the assessment of the chronology and correlation of Lateglacial lake sediments are evaluated.
Late Weichselian/Devensian ice sheets in the North Sea and adjacent land areas.
Authors: NESJE ATLE , SEJRUP HANS PETTER
Published: July 2010

A considerable discussion concerning the extent of the last Scandinavian and Scottish ice sheets has continued for several years. In contrast to earlier models based on an ice sheet extending to the edge of the continental shelf, recent proposals favor a limited geographical and vertical extent and imply that the Scandinavian and British ice sheets did not coalesce in the North Sea. These models indicate an ice‐free, open embayment in the northern North Sea and areas of dry land in the southern North Sea region during the Late Weichselian/Devensian glacial maximum. Late Weichselian ice‐sheet profiles from the North Sea to the adjacent land areas of southern Norway have been tentatively reconstructed. Low‐gradient profiles in the present shelf areas are explained by unconsolidated, deformable sediments on the continental shelf inducing subglacial water pressure and low basal shear stress beneath marginal parts of the Scandinavian ice sheet. Combined with higher basal shear stress conditions in the present mainland areas, this explains the slightly concave and convex shape of the reconstructed ice‐sheet profiles in the present coastal and inland areas of western Norway, respectively.
Late Devensian raised shorelines and ice limits in the inner Moray Firth area, northern Scotland
Authors: FIRTH CALLUM R.
Published: July 2010

Marine, fluvial and fluvioglacial landforms and the deposits associated with them, have been mapped in the inner Moray Firth area. The landforms identified indicate a close association between the decay of the Late Devensian Scottish ice sheet and the formation of raised marine features. Analysis of the altitudes of the marine terraces has identified ten glacio‐isostatically tilted raised shorelines of Late Devensian age, sloping down towards N25°E, at progressively lower gradients between 0.57 and 0.15 m/km. The shorelines were formed in close association with a westward‐ and southward‐receding ice margin and the shoreline sequence suggests that rates of ice margin retreat were most rapid where the ice terminated in the sea.
An early Holocene narwhal tusk from the Canadian high Arctic
Authors: EVANS DAVID J. A.
Published: July 2010

A narwhal(Monodon monoceros)tusk from 34 m above sea level and located at 82°N on the northwest coast of Ellesmere Island has been radiocarbon dated at 6,830 ± 50 B.P. It was collected from a narrow coastal strip which is isolated from the adjacent Arctic Ocean by glacier ice, ice shelf and multiyear pack ice. The specimen represents an early Holocene range extension of 400–700 km over the present. Because the narwhal requires abundant open water to survive, the Holocene tusk is an important independent item of proxy data on palaeoclimatic change. Contemporary migration routes are directly related to seasonal sea ice in the inter‐island channels of the central Canadian Arctic archipelago. The presence of a narwhal on the northwest Ellesmere Island coast at 6,830 ± 50 B. P. suggests that sea ice and ice‐shelf conditions were more favourable at that time. A comprehensive chronological framework for late Quaternary and Holocene geomorphic/climatic events from northern Ellesmere Island records a warm early Holocene characterized by abundant driftwood entry into the high Arctic. This was followed by a mid‐Holocene climatic deterioration during which the ice shelves of the Ellesmere coast formed. Therefore, the narwhal tusk is further evidence that a period of maximum postglacial warmth occurred during the early Holocene in the Canadian high Arctic.
Esker formation and glacier dynamics in eastern Skane and adjacent areas, southern Sweden
Authors: HEBRAND MATS , ÅMARK MAX
Published: July 2010

Eskers were investigated in an area with overall terrestrial deglaciation ‐ the eastern part of the province of Skåne and adjacent areas in southern Sweden. On the basis of the proposed model of esker formation, the dynamics of the receding Weichselian Ice Sheet are discussed. The deglaciation was characterized by the gradual retreat of an active ice sheet, bordered by a zone of thin, stagnant ice. For the most part, the ice sheet was probably at the pressure melting point in a marginal zone, where it was penetrated by surface meltwater which constituted most of the subglacially flowing meltwater. The esker sediments, consisting of glaciofluvially reworked basal debris and basal till, accumulated progressively in an up‐glacier direction. Deposition took place close to the live ice boundary in the zone with stagnant ice that fringed the receding ice sheet. The time‐transgressive formation of the eskers is reflected by repeated sediment sequences (morphosequences), i.e. sedimentary units composed of ridges that merge into extended hummocky deposits in a down‐glacier direction. They represent the momentary deposition of stratified drift in the proximal portion of the zone with stagnant ice.
A collection of papers by Björn Kurtén
Authors: JANIS CHRISTINE
Published: July 2010

A collection of papers by Bjorn Kurth, CHRISTINE JANIS

BJORN KURTEN 1924 11 19‐1988 1228
Two decades of progress in periglacial research
Authors: BENEDICT JAMES B.
Published: July 2010

Two decades of progress in periglacial research
Drumlin formation: a time transgressive model
Authors: MOOERS HOWARD D.
Published: July 2010

Graphical and numerical reconstructions of the Rainy and Superior lobes of the Laurentide Ice Sheet suggest that drumlin formation was time transgressive. Suites of glacial landforms including drumlins, tunnel valleys, eskers, and ice‐collapse features can be correlated with specific recessional ice margins and are used as boundary conditions in the modeling. A contour map of the ice surface is then drawn using a specified basal shear stress. The shear stress can be constant or allowed to vary with position on the bed and is chosen to be consistent with the subglacial regime indicated by field evidence. Assuming that ice flow is parallel to drumlin orientations and perpendicular to the ice surface contours and moraines, the trend of drumlin axes is best accommodated by time transgressive drumlin formation during minor stillstands in the overall ice recession. The alternative, that drumlins were formed while the ice was at the Late Wisconsin maximum limit, requires large spatial variations in the basal shear stress distribution and therefore implies large mass‐balance gradients or large variations in basal sliding velocities over small distances, for which there is little evidence.
Deglaciation environments and evidence for glaciers of Younger Dryas age in Nova Scotia, Canada
Authors: STEA RUDOLPH R. , MOTT ROBERT J.
Published: July 2010

The start of deglaciation is recorded in the Minas Basin region of Nova Scotia by the deltaic, glaciofluvial and glaciomarine sediments of the Five Islands Formation. Shell dates on bottomset beds of a delta at Spencers Island range from 14,300 to 12,600, 14C yearsB.P. The time of complete deglaciation of Nova Scotia is still unknown; the uncertainty is at least partially due to evidence for a climatic oscillation at the end of the Late Wisconsinan. Peat beds were deposited during the interval between 12,700 and 10,500 B.P. They overlie previous glacial and fluvial deposits and are overlain by deposits of various origins. Pollen in these peat beds records the migration of spruce into the region indicating climatic warming, and a subsequent deterioration of climate is recorded by the return of tundra‐like flora. The peat beds are truncated by a variety of deposits, including fluvial gravel and sand, lacustrine sand, silt and clay, and diamictons. Periglacial landforms and structures have been observed in some of these deposits. At Collins Pond, on the shore of Chedabucto Bay, a diamicton overlying a peat bed is characterized by strong fabrics parallel to the trend of other ice‐flow landforms in the region. The evidence suggests that at least some of these deposits are glacigenic, indicating that glaciers were active in Nova Scotia until about 10,000 B.P.
Clast ploughing, lodgement and glacier sliding over a soft glacier bed
Authors: CLARK PETER U. , HANSEL ARDITH K.
Published: July 2010

Rarely‐preserved features indicative of clast lodgement are exceptionally well preserved near Peoria, Illinois, on the contact surface between Illinoian till and underlying glacifluvial sand due to synsedimentary cementation of the substrate contact. Features preserved on the cemented contact surface record a history of particle transport, lodgement by ploughing into a deformable substrate, and subsequent overriding by abrasive debris‐rich ice. Linear grooves and frontal sediment prows suggest that clasts embedded in the glacier sole ploughed through the soft, deformable bed. Increasing form resistance by the enlargement of sediment prows that developed on the lee side of clasts and deeper penetration of the clasts into the substrate eventually exceeded the force exerted on the clasts by ice flow, and the clasts lodged. Subsequently, clasts were abraded on their up‐ice flanks and plucked on their down‐ice flanks, resulting in stoss‐lee morphology. These features offer direct information on the nature of the interface between aglacier and a soft, deformable substrate such as characterized large areas of former ice sheets.
Advances in the reconstruction of past vegetation
Authors: TOLONEN KIMMO
Published: July 2010

Advances in the reconstrucdon of past vegetaion, KIMMO TOLONEN
A palaeoecological study of the mites (Acari) from a Lateglacial deposit at Usselo (The Netherlands)
Authors: SCHELVIS JAAP , GEEL BAS VAN
Published: July 2010

The distribution of the remains of mites in the Lateglacial (Late Weichselian) type section at Usselo (The Netherlands) is presented. The division of the sequence into (sub‐)zones, based upon combined palaeo‐botanical and palaeoentomological studies, is shown, as well as the approximate age based on 14C determinations. The present habitats of the species are in agreement with the reconstruction of the local vegetational succession Four species of mites, three oribatids and one uropodid, have not previously been recorded as subfossils.
The beetles of Greenland ‐ and how they might have got there
Authors: HJORT CHRISTIAN
Published: July 2010

The beetles of Greenland ‐ and how they might have gotthere, CHRISTIAN WORT
Pollen‐ and oxygen‐isotope analyses of late‐ and postglacial sediments from the Schwemm raised bog near Walchsee in Tirol, Austria
Authors: OEGGL KLAUS , EICHER UELI
Published: July 2010

Oxygen‐isotope and pollen analyses were carried out on late‐ and postglacial (Late Weichselian and Holo‐cene) sediment samples of the raised bog. The 18O/16O‐ratio results provide the first unequivocal proof for the Eastern Alps of the climatic deterioration of the Younger Dryas period. High NAP‐values in the pollen diagram and a strong negative deviation in the oxygen‐isotope curve characterize this period. The earlier Gerzensee fluctuation is also indicated by small changes in the oxygen‐isotope curve. During the postglacial the Frosnitz climatic deterioration (6,000–6,500 B.P.) is evidenced as a fluctuation in the lake‐level. The oxygen‐isotope values indicate that the air temperature conditions remained unchanged at that time.
Changing palynological methods and their role in three successive interpretations of the late‐glacial environments at Bucyrus Bog, Ohio, USA
Authors: SHANE LINDA C. K.
Published: July 2010

The pollen stratigraphy of Bucyrus Bog records the major shifts in the spruce ecotone of the mid‐western North American late‐glacial. The site has been studied three times: in 1930 by Paul Sears, in 1958 by Johannes Iversen, and in 1986–88 by my self. This paper examines these data sets from a historical perspective. The pollen record is basically consistent; all investigators interpret it to show the classic late‐glacial warming plus a subsequent, more controversial climate reversal. Sears saw a progressive shift from cold/moist to warm/ dry climate, with a moisture reversal near the top of the record. Iversen and I both correlate the record with the European Late‐Glacial climatic sequence, including an AUerød/Younger Dryas reversal. Iversen's interpretation depends on exclusion of thermophilous deciduous pollen taxa, placing the cold reversal during the spruce decline. I include the deciduous taxa, placing the cold reversal at the time of a spruce recurrence above the expansion of deciduous types. All interpretations are strongly influenced by current technology and prevailing thinking at the time of the investigation.
A classic North American research area
Authors: BJORCK SVANTE
Published: July 2010

A classic North American research area, SVANTE BJORCK
Global palaeoclimate of the Late Cenozoic
Authors: WEST RICHARD G.
Published: July 2010

Zubakov, V. A. & Borzenkova, I. I. (eds.) 1990: GlobalPalaeo‐climate of the Late Cenozoic.
Glacially‐crushed quartz grains in late Quaternary deposits in the Virunga Mountains, Rwanda ‐indicators of wind transport from the north?
Authors: MAHANEY WILLIAM C.
Published: July 2010

Quartz sand grains in late Quaternary deposits of the Virunga Mountains, northwestern Rwanda, were found to contain glacial‐crushing microtextures. Glacially‐crushed subangular grains generally lack sharp edges, and carry mainly low frequency, linear crushing features. Because there are no known tills in the Virunga Volcanoes (and because quartz is rare in volcanic terrain), it is likely the grains were delivered by aeolian transport from the Ruwenzori Massif, ‐150 km to the north. All the grains studied are consistent with crushing under low shear stress, and over short transport distances, in alpine glaciers. An increase in the percentage of glacially‐crushed quartz from Holocene to Pleistocene beds likely reflects on the increased strength of the paleowind system (trade winds) during the last glacial maximum. Alternatively, it could reflect on the increased source area for glacially‐crushed grains resulting from an increase in the extent of the Afroalpine belt during the last glaciation.
A 350,000‐year climatic record from the loess sequence of Achenheim, Alsace, France
Authors: ROUSSEAU DENIS‐DIDIER , PUISSÉGUR JEAN‐JACQUES
Published: July 2010

Up to now the best Quaternary climatic sequences come from oceanic isotope studies, but terrestrial sequences are also well known, usually for pollen or ice core data. A new sequence providing climatic information for the last 500,000 years has been studied in the loess series of Achenheim (Alsace), using the mollusc record in relation to other stratigraphical data. Mollusc assemblages are analysed using a multivariate method. The correspondence analysis used here allows us to explain, in ecological terms, the general variability of the Achenheim set. Most Pleistocene mollusc species have the advantage that modem individuals live in the same assemhlages. So, the known ecology and distribution of the modern molluscs allow us to conclude that the first two factors explain variations in temperature and moisture. Each loading, on a factor, of each association in its stratigraphical level contributes to characterizing the evolution of each climatic parameter through time. For the last five climatic cycles, these evolutions are expressed as a function of the depth within the series. As they are well preserved, the last three glacial cycles are studied in detail. They correspond to the last 350,000 years, are compared with SPECMAP data and particularly show correlations between continental and marine climatic indicators. The mollusc assemblages of the loess sequence also provide information on temperature and moisture conditions. The evolutions of each parameter are not identical during the last three cycles, indicating that the climatic history of one cycle cannot be transferred to the others. The mollusc assemblages also record the occurrence of an oscillatory system, especially during the Weichselian Upper Pleniglacial (isotopic stage 2) when it announces the Late Glacial variations. Similar oscillating excursions seem to have occurred during the older glacial stages.
Reconstruction of ice flow directions south of the Baltic Sea during the Saalian and Weichselian glaciations
Authors: BÖSE MARGOT
Published: July 2010

Till stratigraphical investigations in Berlin have been evaluated using the gravel counting method (4–12.5 mm). The results are compared with studies of several authors from the coastal area north of Berlin (Rügen and Stoltera Cliff near Warnemünde); the gravel counting results from Stoltera Cliff (Cepek 1973) are re‐evaluated by means of cluster analysis, and a new stratigraphical interpretation of the sequence in the cliff is given. These results, together with a discussion of correlation problems of Weichselian and especially Saalian tills south of the Baltic Sea, lead to the following hypothesis: it is proposed that the ice margin of each glaciation has been nourished by several ice flows coming from different directions, for the most part turning from north‐northeast at onset to east‐northeast in later phases. Consequently, differences of composition are found in tills of the same age.
Relative dating of moraines using moraine morphometric and boulder weathering criteria, Kigluaik Mountains, Alaska
Authors: PECK BRIAN J. , KAUFMAN DARRELL S. , CALKIN PARKER E.
Published: July 2010

Six measurements of surface‐boulder weathering and seven measures of moraine morphometrics were taken at 57 sites in the Kigluaik Mountains, Alaska, to test the morphostratigraphic division of five Quaternary glacial units, to test a threefold subdivision of the late Pleistocene glacial unit, and to estimate the timing of glacial advances. Group means from 70% of the relative‐age measures exhibit a positive relationship with relative age of the glacial units. The measures most effective at differentiating between moraine groups were: boulder frequency, tall‐boulder frequency, boulder height, distal slope, and boulder angularity. Results of dixriminant analysis indicate that moraine‐morphometric measures provided slightly better classification results than those of boulder weathering. Discriminant analysis correctly classified 89% of the a priori grouped sites. Multivariate analysis supports the attempted threefold subdivision of the latest Pleistocene Mount Osborn moraines at the 0.056 level of significance. Estimated ages of 60,000 BP for the Salmon Lake and 165,000 BP for the Stewart River glacial units were interpolated by using the relative‐age data and ages of 18,000 BP for the Mount Osborn and 810,000 BP for the Nome River units.
Glacial stratigraphy of East and Central Jutland
Authors: Kronborg Christian , Bender Henry , Bjerre Regnar , Friborg Rud , Jacobsen Hans O. , Kristiansen Lars , Rasmussen Poul , Sørensen Poul R. , Larsen Gunnar
Published: July 2010

Glaciostratigraphic investigations at one key locality (Haldum), 9 major and about 160 minor localities in East and Central Jutland, Denmark, together with laboratory work, have led to the establishment of a stratigraphy consisting of 10 till units, usually separated by meltwater deposits. The stratigraphy is in some degree supported by thermoluminescence datings. The complete sequence includes one till unit with associated meltwater deposits of Menapian age, three till units with intercalated meltwater deposits of Elsterian age, marine sediments deposited during the Holsteininan, and three till units with intercalated of Elsterian age, marine sediments deposited during the Holsteinian, and three till units with intercalated glaciofluvial sedimants of Saalian age. Eemian deposits are present above this level, and the whole sequence is capped by till and meltwater deposits related to three glacial advances during the Weichselian.
The importance of applied Quaternary geology for planning of land use and natural resources
Authors: KNUTSSON GERT
Published: July 2010

Book reviewed in this article:

De Mulder, F. J. & Hageman, B. P. (eds.) 1989: Applied Quaternary Research
A mineral magnetic study of Holocene sedimentation in Lough Catherine, Northern Ireland
Authors: SNOWBALL IAN , THOMPSON ROY
Published: July 2010

A suite of 6 m long Mackereth cores collected from Lough Catherine, Northern Ireland, form the basis of a study of sediment accumulation rates throughout the Holocene. A data set produced by measuring the magnetic susceptibility, artificially induced remanent magnetisations and density of the sediment was used to correlate the cores by means of a sequence slotting algorithm. The resulting sediment accumulation pattern was dated by reference to previous14C and palynological studies. The interpretation of the magnetic logs was complicated by the authigenic formation of the magnetic mineral greigite (Fe3S4) and by magnetite dissolution discovered during a period of low sediment accumulation between the end of the Lateglacial period (10,10014C years B.P.) and the elm decline (5,200 B.P.). More traditional methods of core analysis based on sediment density and also new palynological studies were used to correlate sections of the cores where the magnetic results were least amenable to core matching on account of low downcore variability and low accumulation rate. The accumulation rate, a direct indication of catchment denudation, has accelerated fivefold during the Holocene. The sediment accumulation rate has increased most dramatically since the elm decline at 5,200 B.P., reflecting the increasing degree of human disturbance.
The effect of water depth on ice‐proximal glaciolacustrine sedimentation: Salpausselkä I, southern Finland
Authors: FYFE GILLIAN J.
Published: July 2010

The morphology and sedimentology of the Salpausselkä I moraine in southern Finland were examined in detail, together with the distribution of associated eskers and the glacial geology of the surrounding area. Marked contrasts in the form and stratigraphy of the moraine suggest that there were differences in the style and pattern of sedimentation along the ice/lake interface. These variations were influenced by the lake water depth and the nature of the subglacial drainage system. Large individual deltas which built up to water level were the product of conduit focused sedimentation. Lower, narrower coalescing fans of finer material were formed at the ice grounding line by sediment fed from a distributed drainage system. Subglacial conduit systems were found to be unstable where marginal water depths were greatest, favouring the development of a distributed drainage system.
Proglacial glaciotectonic deformation and the origin of the Cromer Ridge push moraine complex, North Norfolk, England
Authors: HART JANE K.
Published: July 2010

The landscape of northeast Norfolk is dominated by a high (>50 m) ridge which has been interpreted as an end moraine (Cromer Ridge). This feature is truncated by coastal erosion at Trimingham. Evidence of large‐ and small‐scale compressive styles of deformation is found throughout the sequence, except at the very top, where late Anglian/early Hoxnian lake sediments are found within an undeformed kettle hole. The deformation consists of open folds (including chevron folds) and listric thrust faults. It is suggested that these are the result of a single compressive event, which was caused by proglacial glaciotectonic deformation. It is inferred that this deformation is due to a combination of frontal pushing and compressive stresses transmitted through a subglacial deforming wedge. It is also shown that strain increases towards the ice sheet margin, as reflected by the deformational styles (from open folding up‐glacier to listric thrust faulting down‐glacier). The Cromer Ridge is shown to be a push moraine complex related to an actively retreating ice margin.
Textbook of pollen analysis ‐ once again!
Authors: FREDSKILD BENT
Published: July 2010

Book reviewed in this article:

Faegri, K. & Iversen, J. 1989: Textbook of Pollen Analysis
An Early or Middle Weichselian sequence of proglacial, shallow marine sediments on western Svalbard
Authors: LONNE IDA , MANGERUD JAN
Published: July 2010

A 20 m thick shallow marine sequence, capped by a Late Weichselian lodgement till, is exposed for 200111 along the river in Linnedalen on the west coast of Svalbard. Five formations are recognized: Formation A, the oldest, consists of a shallow marine, proglacial fan, of channelized sandy turbidites, possibly fed from an ice‐contact deposit. Formation B, a sequence of proglacial channels and ice‐rafted debris, was formed during a small oscillation of the glacier. Formation C, a prograding, storm‐dominated shoreline sequence, was formed during a sea level fall, assumed to be a result of glacio‐isostatic uplift.

Formation D, a lodgement till formed during the last glacier advance in Linnedalen and formation E, a coarsening upwards sequence, were formed during the post‐glacial sea level fall. The subtill sequence (fm. A, B and C) is dated to between 40,000BP (radiocarbon dates) and 120,000BP (thermoluminescence and amino acid D/L ratios). The glacier front was 10 km downvalley during deposition of formations A and B, relative to the present glacier terminus, and more than 12km during the late Weichselian maximum.
The significance of pollen‐rich inorganic lake sediments in the Cratére du Nouveau‐Quèbec area, Ungava, Canada
Authors: RICHARD PIERRE J. H. , BOUCHARD MICHEL A. , GANGLOFF PIERRE
Published: July 2010

Unexpectedly high pollen concentrations characterize the basal, silty part of the postglacial sediments accumulated in two lakes from the Cratère du Nouveau‐Quebéc area, Ungava. These lacustrine silts and their pollen content result from early postglacial washing of a pollen bearing till. The till must therefore ahve incorporated pollen that relates to events prior to the last glacial event. The matrix of the till deposits surrounding the lakes shows outstandingly high pollen concentrations. It is hypothesized that because of the proximity of the ice divide during the last (and earlier) ice advance(s) in Ungava, the previously depoisited till and the pollen that haad accumulated in its matrix during the interglacial interval(s) were preserved in relict till plains or recycled into the till of teh last glaciation. The crater's age has been established at 1.4 Ma and holds a minimum thickness of 95 m of sediments. It is very likely filled with successive tills or related glacigenic deposits perhaps representing the whole length of time since the crater was formed. Alike the most recent till, these deposits should pollen. there is thus the prospect ofr a 1.4 Ma old pollen record for Ungava.
Younger Dryas in southern South America?
Authors: MARKGRAF VERA
Published: July 2010

Two high resolution pollen records, Caunahue from mid‐latitudes and Harberton from high latitudes, illustrate the issues in defining the Younger Dryas episode in records from southern South America. At mid‐latitudes in the Chilean lake region, previous claims for the existence of a substantially cooler and wetter episode between 11,000 and 10,000 BP can no longer be supported by new pollen records with high temporal and paleoenvironmental resolution, such as Caunahue. The transition from glacial to interglacial conditions occurred in several steps, one shortly after 13,000 BP, when open Nothofagus woodland was replaced by cool‐temperate North Patagonian forest, and one at 9,500 BP, when warmtemperate Validivian forest elements replaced the North Patagonian elements. At high latitudes, on the other hand, high resolution records do show marked short‐term changes during the late‐glacial, inclding the 11,000 to 10,000 BP Interval. However, neither the exact timing nor the duration of these changes is synchronous for specific taxa, neither within one record nor between different records. One of the two intervals of low pollen influx that has been singled out as evidence for a cooler episode is consistently dated between 11,000 and 12,000 BP, while the other interval dates between 10,800 and 9,000 BP. Based on all this information I believe that there is no evidence of Younger Dryas episode for the midlatitudes. For the high latitudes, on the other hand, the overall high paleoenvironmental variability in the records offers multiple choices for a Younger Dryas‐type interval if specific taxa are selected without considering the overall context. However, the lack of synchroneity between short‐term changes of specific taxa between different records suggests primarily a response to local disturbances, rather than a response to a global forcing.
Late Weichselian glacial maximum on Andøya, North Norway
Authors: MØLLER JOKOB J. , DANIELSEN TOR K. , FJALSTAD ARNE
Published: July 2010

Morphological, seismic and lithostratigraphic investigations of a moraine deposit at Bleik (the Bleik moraine), northern Andøya, show short‐distance transported till overlying long‐distance transported predominantly glaciofluvial ice‐marginal deposits. Consolidated glaciomarine sediments from a core at present sea‐level,c. 400 m distally to the moraine complex, contain 31 species of foraminifera, among whichCassidulina reniforme, Islandiella helenaeandTrifarina fluensdominate, and fragments of the molluscsMya truncataandAstartesp. and the echinoidStrongylocentrotussp. Amino acid analyses of the foraminiferaCibicides lobatulusand the molluscMya truncataindicate ages between 22,000 and 16,000 BP. Radiocarbon dating of fragments ofMya truncatafrom the upper part of the core gave an age of 17,940 ± 245 BP, while a dating of unidentified shell fragments from the lower part gave an infinite age (>40,000 BP). The sediment was probably disturbed by icebergs beyond the end moraine zone, and the radiocarbon and amino acid dating ofMya truncatatherefore represent a maximum age for this process. This new evidence indicates two phases with a higher relative sea‐level than at present at Bleik,c. 18,000 and >40,000 BP. The Bleik moraine probably represents the early Late Weichselian glacial maximum (c. 22,000 BP), while the underlying deglaciation deposit and associated beach‐ridge (Bruvollen) is of pre‐Late Weichselian age. Moraine ridges 3–4 km to the south of Bleik probably indicate advances of local glaciers between 22,000 and 18,000 BP.
A wealth of paleoclimatological information — in addition, free of charge!
Authors: BJÖRCK SVANTE
Published: July 2010

Book reviewed in this article:

Bradley, R. S. (ed.) 1991: Global Changes of the Past. 514 pp. Office for Interdisciplinary Earth Studies, Boulder, Colorado
Environmental change in Iceland: past and present
Authors: HUMLUM OLE
Published: July 2010

Book reviewed in this article:

Maizels, Judith K. & Caseldine, Chris (eds.) 1991: Environmental Change in Iceland: Past and Present.
Lobal interactions and rheologic superposition in subglacial till near Bradtville, Ontario, Canada
Authors: HICOCK STEPHEN R.
Published: July 2010

Structural, stratigraphic, and lithologic data from a section 69 m long of Catfish Creek drift (north shore of Lake Erie) tell a complex story of two competing glacial lobes. Stone surface features and orientations indicate that stones rotated in viscously deforming, fine‐medium textured subglacial till prior to final emplacement. Fractures, shears, and attenuated sediment lenses in tills reveal that they experienced some brittle shear superposed on ductile shear during till dewatering and stiffening. The Huron‐Georgian Bay lobe advanced first from the northwest, deforming interstadial sediments and depositing subglacial till. Next, southward confluent flow of the Huron, Georgian Bay, and Erie lobes carved subglacial troughs into sediments and deposited (then deformed) bouldery deformation till by squeeze flow. The northwest flowing Erie lobe then prevailed, depositing deformation till, subglacial aquatic sediments, and mudflows. Finally, a pavement‐bearing, hybrid deformation‐lodgement till covered the section. Till formation was mainly by subglacial viscous flow with minor lodgement superposed as water content decreased and some fines were probably winnowed. This implies that till deformation probably accounted for much of the glacier movement. Therefore, rapid ice flow could have occurred over the section, along the southern margin of the Laurentide Ice Sheet.
A comprehensive inventory on glacigenetic sediments and facies
Authors: HOUMARK‐NIELSEN MICHAEL
Published: July 2010

Book reviewed in this article:

Brodzikowski, K. & van Loon, A. J. 1991: Glacigenetic Sediments. Developments in Sedimentology
Terrestrial molluscs as indicators of global aeolian dust fluxes during glacial stages
Authors: ROUSSEAU DENIS‐DIDIER
Published: July 2010

This paper represents an approach to discerning the kind of climatic signal that land snails might record. The study uses previous analyses of the Achenheim molluscs, whose time series can be compared with ice‐core records or marine records. Terrestrial molluscs are characteristic of the environment in which they live, mainly mirroring prevailing climate and vegetation. As a result of this relatively close connection between biotope and mollusc assemblages, reconstructions of past environments can be made that agree generally with results from pollen analyses. In this way, malacofaunas in loess sections permit determination of environmental variability and climatic change. Loess deposits, however, correspond to a particular environment. Decreasing or increasing dust deposition affects the molluscan assemblages by altering the environmental conditions for better or for worse. The variation in the mollusc diversity index in Achenheim shows a striking correspondence with dust‐flux variation. There is only a low correlation between diversity index and temperature, precipitation or moisture estimates.
Recent sedimentary processes in Scoresby Sund, East Greenland
Authors: MARIENFELD PETER
Published: July 2010

The fjord system of Scoresby Sund on the east coast of Greenland has been the subject of two research cruises by RV Polarstern in 1988 and 1990. Most of the year, the fjord is covered by sea‐ice. Sediment input takes place mostly via drifting icebergs during the short summer period. Depending on the distance to glaciers, surface sediments carry varying proportions of coarse ice‐rafted debris (IRD). The degree of sediment reworking by scouring icebergs is controlled by the depth of the fjord, with the most intense reworking in areas shallower than about 450 m depth. Both IRD contribution and intensity of sediment scouring clearly control the distribution pattern of benthic organisms.
A stimulating (but uneven) textbook on Ice Age Earth
Authors: INGÓLFSSON ÓLAFUR
Published: July 2010

Book reviewed in this article:

Dawson, Alastair, G. 1992: Ice Age Earth. Late Quaternary Geology and Climate
Late Quaternary foraminiferal stratigraphy from western Svalbard
Authors: LYCKE ANNE KATRINE , MANGERUD JAN , SEJRUP HANS PETTER
Published: July 2010

In the lower part of sections at Skilvika and Linneelva, western Svalbard, marine silts and sands characterized by infinite radiocarbon ages (<40,000 BP) on shells are found. These sediments are covered by at least one basal till of Late Weichselian age. The till is overlain by marine sediments from the last deglaciation (12,800‐10,000 BP) which contain shallow‐water, subarctic foraminiferal assemblages, similar to modern near‐glacial faunas from western Svalbard. The most common foraminifera in all zones in the sub‐till sediments are Cassidulina reniforme, Astrononion gallowayi and/or Elphidium excavatum. The richest zones at both localities are found in the sub‐till units and contain more than 20 foraminiferal species, including some boreal‐arctic species. These faunal assemblages are similar to the living faunas on the west coast of Svalbard. Faunas from the postglacial climatic optimum are not yet described. We suggest that the foraminiferal assemblages in the sub‐till sediment reflect Early or Middle Weichselian interstadial environments, although an Eemian interglacial cannot be excluded.
Holocene lake‐level fluctuations in Jura and the northern subalpine ranges, France: regional pattern and climatic implications
Authors: MAGNY MICHEL
Published: July 2010

Holocene lake‐level fluctuations in Jurassian and French subalpine lakes are reconstructed using sedimentological analysis, and a regional pattern of palaeohydrological changes is put forward. Major transgressive phases culminated at about 8500 BP, 6500 BP, 4800 BP, 3500–2300 BP and 450 BP. (1) The synchroncity of Holocene lake‐level changes demonstrated for a large number of lakes, (2) close correlations attested between certain lakes and (3) the coincidence between rises in lake‐levels in Jura and French subalpine ranges, and glacier advances in Swiss and Austrian Alps argue for a climatic control of these Holocene lake‐level fluctuations.
Weichselian stratigraphy and palaeoenvironments at Bellsund, western Svalbard
Authors: LANDVIK JON Y. , BOLSTAD MAGNE , LYCKE ANNE KATRINE , MANGERUD JAN , SEJRUP HANS PETTER
Published: July 2010

A coastal cliff facing the ocean at the west coast of Spitsbergen has been studied, and seven formations of Weichselian and Holocene age have been identified. A reconstruction of the palaeoenvironment and glacial history shows that most of the sediments cover isotope stage 5. From the base of the section, the formation 1 and 2 tills show a regional glaciation that reached the continental shelf shortly after the Eemian. Formation 3 consists of glacimarine to marine sediments dated to 105,000–90,000 BP. Amino acid diagenesis indicates that they were deposited during ac. 10,000‐year period of continuous isostatic depression, which indicates contemporaneous glacial loading in the Barents Sea. Foraminifera and molluscs show influx of Atlantic water masses along the west coast of Svalbard at the same time. Local glaciers advanced during the latter part of this period, probably due to the penetration of moist air masses, and deposited formation 4. A widespread weathering horizon shows that the glacial retreat was succeeded by subaerial conditions during the Middle Weichselian. Formation 5 is a till deposited during the Late Weichselian glacial maximum in this area. The glaciation was dominated by ice streams from a dome over southern Spitsbergen, and the last deglaciation of the outer coast is dated to 13,000 BP. A correlation of the events with other areas on Svalbard is discussed, and at least two periods of glaciation in the Barents Sea during the Weichselian are suggested.
Preparing pollen concentrates for AMS dating – a methodological study from a hard‐water lake in southern Sweden
Authors: REGNÉLL JOACHIM
Published: July 2010

Dating pollen concentrated from sediment samples is a way to improve lake‐sediment chronology. The predominantly terrestrial origin of pollen assemblages minimizes, for example, the reservoir effect inherent in bulk sediment samples, especially from hard‐water lakes. Pollen can be concentrated for dating by a combination of sieving and chemical treatment (Brown et al. 1989). This study illustrates the difficulty in applying a single, standard procedure, and demonstrates the need for flexibility depending on lake sediment characteristics and the particular pollen flora. Samples taken at the Ulmus decline were prepared and AMS‐dated following different steps of the pollen concentration procedure. The results showed that both sieving and chemical treatment were needed to obtain an age close to the expected age for the Ulmus decline. The pollen concentrate dated c. 1000 years younger than a bulk date from the same level, but is close to the expected age based on correlation with dates for the Ulmus decline from Sphagnum peat sequences in north‐western Europe. A compilation of bulk dates at the Ulmus decline implies that pollen concentrates would be a better material for dating than bulk samples for many lake sediments, not only for those from hard‐water lakes.
The early Holocene Saksunarvatn tephra found in lake sediments in NW Germany
Authors: MERKT JOSEF , MÜLLER HELMUT , KNABE WOLFGANG , MÜLLER PETER , WEISER THOROLF
Published: July 2010

A basaltic tephra layer consisting of brownish‐olive glass shards. and about 0.2 mm thick. was found in cores from four lakes in northwest Germany. According to pollen analysis it was deposited during the early Boreal period (corresponding to about 8700 BP). The petrographic properties. the geochemical composition and the age agree with those of the Saksunarvatn tephra. which was first found on the Faroe Islands. The position of the tephra layer in the pollen stratigraphy and in the absolute time‐scale is discussed. Procedures for locating the tephra in other cores are suggested.