bluuebunny/crossref_metadata_2025 huggingface dataset:
Lithological stratification in supraglacial sediments: an example from western Tasmania, Australia
Authors: FITZSIMONS SEAN J.
Published: July 2010

Pebble counts of the lithology of glacial sediments in the King Valley show that the content of distantly derived erratics of many sections decreases upwards in near surface sediments. Two factors that contribute to this lithological stratification are dilution of the erratic content of surface sediments by locally derived rocks and lithological stratification of debris within the Pleistocene King Glacier. The common diluting mechanism appears to have been slope detritus derived from the valley sides and small hills that crop out on the valley floor. Lithological stratification of debris in the King Glacier resulted from the altitude of the equilibrium line of the King Glacier relative to the position and altitude of the rock source areas and the thermal regime at the ice‐bed interface. The Jurassic dolerite and Permian sediments that crop out above the equilibrium line altitude were transported in subglacial and englacial positions. In contrast, below the equilibrium line sediments that accumulated and were transported in a supraglacial position contained no erratic lithologies. When deposited, the supraglacial sediments formed a siliceous, non‐erratic cover over sediments that were transported in subglacial and englacial positions. The model of the mode of sediment transport in the King Valley may have application to areas of alpine glaciation where the distribution of some rock types is restricted to areas above the equilibrium lines of glaciers.
East Africa during the Quaternary
Authors: ROSQVIST GUNHILD
Published: July 2010

East Africa during the Quaternary, GUNHILD ROSQVIST
Erosion: uniform aim of a variety of research trends
Authors: KOSTRZEWSKI ANDRZEJ , STACH ALFRED
Published: July 2010

Erosion: uniform aim of a variety of research trends, ANDRZEJ KOSTRZEWSKI AND ALFRED STACH
A new method of coring in deep lakes with rod‐operated samplers
Authors: WIIȨKOWSKI KAZIMIERZ
Published: July 2010

A new simple method of using a stretching device to stabilize coring rods in deep water is described. The method can be used for sediment coring with rod‐operated samplers in lakes of a water depth down to 30–40 m.
Middle and Late Weichselian stratigraphy and palaeoenvironments in central Poland
Authors: KRZYSZKOWSKI DARIUSZ
Published: July 2010

The moraine plateau near BetchatÓw (central Poland) was incised at the beginning of the Middle Weichselian. Valleys 20–35 m deep were formed and then infilled with silts, sands, gravels, organic sediments and slope diamictons of the Piaski Formation, which is characterized by highly varying sedimentary environments. Initially ‐ 40,000–30,000 BP ‐ lacustrine sediments with an obvious colian supply (re‐worked loess) and locally fluvial suites were deposited in depressions. Slope sediments were simultaneously deposited at the valley margins. The Middle Weichselian was relatively mild and dry, but the milder interstadial periods have not been precisely established. Semi‐anastomosing, stable‐channel, highly aggrading and ephemeral streams of a semi‐arid climate (subpolar desert) formed c. 30,000–22,000 BP. Continuous permafrost is implied from cyclic sedimentary processes reflecting summer melting and from periglacial structures. This was succeeded by a highly aggrading, high‐energy and ephemeral braided fluvial system in an arid climate (polar desert), reflecting a complete lack of vegetation and increased eolian activity. These braided rivers formed during a period which may be directly correlated with the time of the maximum extent of the last ice sheet (22,000–14,350 BP), characterized by the most severe climatic conditions with strong periglacial activity. Finally ‐ (14,350‐12,700 BP)‐ eolian sediments were deposited, reflecting milder climatic conditions at the time of the abrupt ice sheet decay.
Application of brachiopods in palaeoceanographic reconstructions; Macandrevia cranium (Müller, 1776) from the Norwegian shelf
Authors: THOMSEN ELSEBETH
Published: July 2010

The brachiopod Macandrevia cranium (Müller, 1776) occurs in Late Weichselian and Holocene sediments from the Norwegian continental shelf. It is particularly well known from the southern Barents Sea where it is a characteristic member of the Holocene macrofpssil assemblages. The Recent biogeography of the species is established. The general distribution is not random, but is almost completely confined to the continental shelves surrounding the North Atlantic and the Norwegian‐Greenland Sea. The distribution pattern is compared with information on autecology and possible limiting environmental factors. It is concluded that there is substantial evidence that the distribution of Recent M. cranium is a function of dispersal by the Gulf Stream and its continuations, e.g. the Norwegian Current and the North Cape Current. Thus the stratigraphic occurrence of M. cranium in sediments on the Norwegian continental shelf may be used as an important marker for the presence of Atlantic water. Late Weichselian records of rare specimens of the species are related to incipient influx of Atlantic water following the deglaciation. Early Holocene records of abundant specimens are related to the final intrusion of the Norwegian Current. These records also suggest that the Holocene introduction of the species is time‐transgressive in a south‐north direction.
Weichselian palaeoenvironments at Kobbelgård, Møn, Denmark
Authors: KOLSTRUP ELSE , HOUMARK‐NIELSEN MICHAEL
Published: July 2010

Lithostratigraphical and palynological investigations of a coastal cliff section at Kobbelgård, Møn (Denmark) reveal a sedimentary sequence of Weichselian age. Bedded clayey sediments are overlain by stratified silt, sand and occasional beds of clay and gravel. The clay was deposited in water, and most of the silt and sand is aeolian, forming fairly thick units of loess and sand‐loess. The lower part of the sequence forms an anticlinal structure, probably of glacio‐tectonic orìgìn. The upper part of the sequence appears to represent a depression filling. In the lower part of this, clayey layers alternating with loess deposits suggest wet conditions periodically. In the upper part, loess and fine sand were deposited, interfingering with slope sediments in a periglacial environment from around 24,000 BP almost until the Weichselian glacial maximum. Pollen investigations at the site point to three periods of vegetation. The lowest pollen sequence contains much Ericales, Empetrum and occasionally also Pinus, and is thought to be of Early Glacial or Lower Pleniglacial age. Overlying pollen‐bearing strata with high proportions of herbs, including Artemisia, antedate a TL dating of c. 27,000 BP. An upper pollen sequence, derived from slightly organic layers in the depression fill, points to a palaeovegetation almost exclusively of herbs, with Artemisia as an important component. This vegetation is thought to represent a relatively moist site, and is TL dated to c. 24,000 P.
The Jura glaciers: palaeogeography in the Würmian circum‐Alpine zone
Authors: CAMPY MICHEL , ARN ROBERT
Published: July 2010

Since the first studies on the glacial formations of the Jura mountains there have been two concepts concerning type of glaciation and ice origin during the Würmian glaciation. Some authors believed that the Jura was totally inundated by ice of Alpine origin, while others believed that the Jura had its own glaciers, originating from a single ice‐cap. Several recent studies on both the NW and SE slopes of the range define the problem more accurately. This paper presents a synthesis of the new results from mapping the moraine systems and studying the stratigraphic relationships between Alpine and Jura tills. It is concluded that even the highest level of Alpine glaciers could not lead to a penetration of the Jura. A reconstruction of the extension of the Jura glaciers and their relationship with the Alpine glaciers is given, and we conclude that at the Würmian maximum a local ice‐cap was present.
Challenging problems in land‐sea interactions
Authors: BJÖRCK SVANTE , SVENSSON NILS‐OLOF
Published: July 2010

Book reviewed in this article:

Sabadini. R., Lambeck, K. & Boschi, E. (eds.) 1991: Glacial Isostas, Sea‐Level and Mantle Rheology
Late Pleistocene and Holocene glacial history of James Ross Island, Antarctic Peninsula
Authors: INGÓLFSSON ÓLAFUR , HJORT CHRISTIAN , BJÖRCK SVANTE , SMITH R. I. LEWIS
Published: July 2010

Studies of Quaternary glacial stratigraphy and morphology around the Antarctic Peninsula have shown that James Ross Island in the western Weddell Sea probably has the best occurrences of stratigraphic sections with dateable material in the region. The stratigraphy includes sections with indefinite radiocarbon age, and three separate aminozones can be recognized. Except for indications of an early deglaciation around c. 10,000 BP, the field evidence from northern James Ross Island suggests a glacial readvance around 7000 BP. It is concluded that the readvance reflects the combined effects of eustatic sea level rise and Holocene warming, leading to increased precipitation and a positive mass balance. The most recent large‐scale deglaciation in the area took place around 6000–5000 BP. This confirms the evidence from lake sediments and moss banks in other parts of the Antarctic Peninsula region, which shows that, in most cases, the initiation of organic deposition took place after c. 6000 BP. The literature on the Holocene glacial and environmental history of the region is reviewed in light of the new field evidence.
Pleistocene stratigraphy in the Lappajarvi meteorite crater in Ostrobothnia, Finland
Authors: SALONEN VELI‐PEKKA , ERIKSSON BRITA , GRÖNLUND TUULIKKI
Published: July 2010

Seventy‐four meters of a 95‐m‐long drill core recovered from the Lappäjarvi crater, a meteoritic impact site in western Finland, consisted of Pleistocene sediments. These sediments refer to two events of glacial deposition (Saalian and Weichselian) interrupted by non‐glacigenic freshwater sedimentation. The sediments contain abundant redeposited Holsteinian and Tertiary microfossils, and possibly represent a pre‐Weichselian interstadial not described from elsewhere in Finland. The pollen flora indicates a mixed primary arctic to subarctic succession that followed deglaciation, i.e. the beginning of an interglacial or interstadial event. The secondary pollen component derives from an eroded interglacial deposit that can be interpreted as Holsteinian, or possibly Eemian, in age. The vegetation succession interpreted from the primary pollen flora reflects a transition from arctic conditions to subarctic birch forests. The diatom flora indicates a primary succession that can be observed clearly in the uppermost gyttja layer in which the rich alkaliphilous diatom flora refers to more or less eutrophic conditions. The diatom flora of sediments below the gyttja layer is composed of a primary component and a secondary, redeposited or relict component. The diatoms encountered are interglacial or Tertiary in origin. The results show that meteorite craters can provide long, representative stratigraphic sequences in glacially eroded Precambrian shield areas such as Finland.
Middle Valdaian forest environments at Biržai, northern Lithuania
Authors: GAIGALAS ALGIRDAS , SEREBRYANNY LEONID , VALUEVA MAISA
Published: July 2010

Lacustrine sediments, 13 m thick, have been discovered under a Late Valdaian (Late Weichselian) moraine complex in a palaeokarst depression at Biržai, northern Lithuania. Wood fragments from silty layers in the basal part of the section were 14C dated at 34,440 ± 1500 (Vs‐412) and 33,460 ± 1060 BP (LU‐1633). Pollen analytical results suggest that taiga landscapes similar to the present‐day environments in the Pechora Basin and eastern Urals occurred on the southern cryogenic grounds. Evidently, the ice sheet did not penetrate into the eastern Baltic region during the Middle Valdaian interval.
The pre‐Holocene marine limit on Hopen, Svalbard
Authors: ZALE ROLF , BRYDSTEN LARS
Published: July 2010

A pre‐Holocene marine level is found at 109 m a.s.1. on Hopen. Fragments of Mya truncata and Hiatella arctica occurring on a raised coastal spit at that altitude have been radiocarbon dated to >45,000 BP. The amino acid epimerization of these shells, a clearly mixed sample, correlates with samples from Kongsøya that are of Eemian or Early Weichselian age (alloisoleucine/isoleucine ratios, hydrolysed fraction, between 0.084 and 0.213). No direct evidence, such as striations or roche moutonées, of overriding glacier ice has been found, and no erratics were found above the pre‐Holocene marine limit. The existing Holocene shoreline displacement curve, with its upper limit at 60 m a.s.1., is supported by four new radiocarbon dates.
Subrecent changes in the foraminiferal distribution in the Kattegat and the Skagerrak, Scandinavia: anthropogenic influence and natural causes
Authors: SEIDENKRANTZ MARIT‐SOLVEIG
Published: July 2010

Foraminifera from surface samples in the Kattegat and the Skagerrak, northwestern Europe, have been analysed to determine the modern foraminiferal distribution. A total of five foraminiferal assemblages are distinguished. These are the Elphidium excavatum, Cassidulina laevigata, Bulimina marginata, Cibicides lobatulus and Trochammina sp. assemblages. Only the first three are found over large areas and these are correlated to either depth, organic carbon content or grain size. At each station a short core was studied to determine whether changes have occurred in the assemblages during the last few hundred years. In some areas no such variations were found, but several of the cores from the Skagerrak and all cores from the Kattegat document changes within this period. The fluctuations in the Skagerrak may be attributed to natural causes, such as species migrations or re‐deposition. In the Kattegat a change from a Hyalinea balthica assemblage to the modern B. marginata assemblage always occurs at approximately the same core depth, which presumably represents the biological mixing depth. This change is presumably due to anthropogenic influences, which have caused oxygen depletion in the bottom waters of the Kattegat during the last few decades.
Sedimentology of Wartanian outwash near Bełchatów, central Poland
Authors: KRZYSZKOWSKI DARIUSZ
Published: July 2010

The braided outwash of Wartanian age near Bełchatów, central Poland, was formed synchronously by two river systems: glacier streams flowing from the northwest and west and periglacial rivers flowing from the south and southwest. An extensive alluvial fan was formed which later developed into a highly aggrading fan due to a rising water level in the proglacial lake to the north. Braided streams were represented by relatively low‐energy systems with shallow‐channel and/or transverse bar deposition. Sporadically, rapid inflows of meltwater caused more energetic conditions and formation of large scours. The latter were found only in the glacier streams and this was confirmed by palaeocurrent measurements and analyses of quartz roundness.
Younger Dryas deglaciation at Mt. Billingen, and clay varve dating of the Younger Dryas/Preboreal transition
Authors: STRÖMBERG BO
Published: July 2010

A clay varve chronology has been established for the Late Weichselian ice recession east of Mt. Billingen in Västergötland, Sweden. In this area the Middle‐Swedish end moraine zone was built up as a consequence of cold climate during the Younger Dryas stadial. A change‐over from rapid to slow retreat as a result of climatic deterioration at the Alleröd/Younger Dryas transition cannot be traced with certainty in the varve sequences, but it seems to have taken place just before 11,600 varve years BP. The following deglaciation was very slow for about 700 years — within the Middle‐Swedish end moraine zone the annual ice‐front retreat was only c. 10 m on average. A considerable time‐lag is to be expected between the Younger Dryas climatic event and this period of slow retreat. The 700 years of slow retreat were succeeded by 200 years of more rapid recession, about 50–75 m annually, and then by a mainly rapid and uncomplicated retreat of the ice‐front by 100–200 m/year or more, characterizing the next 1500 years of deglaciation in south and central Sweden. The change from about 50–75 m to 100–200 m of annual ice‐front retreat may reflect the Younger Dryas/Preboreal transition. Clay‐stratigraph‐ically defined, the transition is dated at c. 10,740 varve years BP, with an error of +100 to ‐250 years. In the countings of ice layers in Greenland ice cores (GRIP and GISP‐2) the end of the Younger Dryas climatic event is 800–900 years older. However, a climatic amelioration after the cold part of the Younger Dryas and in early Preboreal should rapidly be reflected by for example chemical components and dust in Greenland ice cores, and by increasing δ13C content in tree rings. On the other hand, the start of a rapid retreat of the inland ice margin can be delayed by several centuries. This can explain at least a part of the discrepancy between the time‐scales.
The Late Quaternary sedimentary record in Scoresby Sund, East Greenland
Authors: DOWDESWELL JULIAN A. , UENZELMANN‐NEBEN GABRIELE , WHITTINGTON ROBERT J. , MARIENFELD PETER
Published: July 2010

Until recently, little was known about the Quaternary marine sedimentary record in East Greenland. Geophysical and geological investigations in Scoresby Sund were undertaken to characterize the nature and chronology of this record. Seismic records show that almost 70% of the outer fjord system is covered by about 10 m of unlithified sediments, making direct correlation with the Quaternary records on land and the adjacent continental margin difficult. These acoustically unstratified sediments are scoured by icebergs above 550 m water depth. Almost 90% of core material is massive diamicton of Holocene age, deposited mainly from iceberg rafting and turbid meltwater. Sedimentation rates are 0.1 ‐0.3 m 1000 yr‐1. Thicker accumulations of unlithified Quaternary sediments in Scoresby Sund occur as sediment ridges and in two other major depocentres. A low sediment ridge runs across the mouth of Scoresby Sund, and is interpreted as an end moraine of Late Weichselian Flakkerhuk stadial age. The very restricted sediment thickness suggests that grounded ice filled the fjord during the Flakkerhuk and an ice shelf was not present. High inputs of ice rafted debris to the continental margin at about 18 000 BP indicate this as a probable age for the moraine. During the Allerød Interstadial, ice probably retreated from the outer fjord system, since massive diamictons similar to those of Holocene age are present at the base of most cores. A major depocentre of acoustically stratified sediments at the head of Hall Bredning is interpreted to represent ice proximal deposits from a glacier margin extending across the fjord. It is adjacent to dated moraines on land and is inferred to be of Milne Land stadial age (about 10 000 BP). A similar age is interpreted for acoustically laminated sediments and a moraine at the entrance of Vikingebugt, on the south side of Scoresby Sund. Dated kame terraces in the inner fjord system indicate that ice retreated to its present position 6–7000 years ago.
Late Pleistocene stratigraphy and depositional environments of the Fynselv area, Jameson Land, East Greenland
Authors: HANSEN LOUISE A. , ØRGENSEN MORTEN E. , HOUMARK‐NIELSEN MICHAEL , KRONBORG CHRISTIAN
Published: July 2010

Deposits of Late Pleistocene age were investigated near the Fynselv river on the southwestern coast of Jameson Land. East Greenland. The deposits are of fluvial, deltaic shallow marine and glacigenic origin. Four stratigraphic units are recorded. Unit I consists of deltaic and shallow marine deposits reflecting a relative sea level of at least 20 m above the present. Elevated fluvial deposits represent the subaerial part of the depositional system. The system existed during full interglacial and subarctic conditions as indicated by remains or flora and Fauna and unit I is correlated with the Langelandselv interglaciation (isotopic substage 5e). Unit II consists of a till deposited by a glacier in the Scoresby Sund Fjord during the beginning of the Early Weichselian referred to as the Aucellaelv stade. The glacier probably melted in a marine environment. Unit III represents a marine delta system during the Hugin Sø interstade. and reveals a relative sea level of at least 62 m above the present. Unit IV consists of till and kame deposits assumed to be deposited by a glacier in the Scoresby Sund Fjord during the Flakkerhuk stade. probably a Late Weichselian glacier advance.
Lake Boksehandsken's earliest postglacial sediments and their palaeoenvironmental implications, Jameson Land, East Greenland
Authors: BJÖRCK SVANTE , BENNIKE OLE , INGÓLFSSON ÓLAFUR , BARNEKOW LENA , PENNEY DAVID N.
Published: July 2010

Lake Boksehandsken, the largest lake on Jameson Land, central East Greenland, is situated 54 m a.s.l. and holds a long (6.3 m) and complex stratigraphy. It was analysed with respect to lithology, carbon content,14C, micro‐ and macrofossils. The diamict material in the bottom is overlain by a fining‐upwards sequence, possibly deposited close to a receding ice margin in a glaciomarine environment. These deposits are interpreted to have been formed at the time of the marine limit (c. 70 m) in the area. In spite of a large series of14C datings, very few of the obtained dates were considered reliable. This is because the sediments contain coal fragments and old redeposited plant remains. Based on a set of arguments and correlations to the surrounding glacial stratigraphy it is implied that the marine limit and deglaciation cannot be much older than 10,000 BP. The lithology of the lake sediments, in combination with occurrence of marine macrofossils. shows that deglaciation was succeeded by a (glacio)marine depositional environment. The lake was isolated from the sea atc. 9000 BP. followed by a short transgression and a final isolation atc. 8400 BP. This sequence of events is demonstrated by both litho‐and biostratigraphy and possible causes are discussed. A later oscillation some time between 8000 and 7500 BP. evidenced by litho‐, carbon‐, pollen‐ andPecliastrumstratigraphy, is interpreted as a regional climatic cooling possibly correlatable to a distinct δ18O minima in the Greenland ice cores.
Quaternary erosional surfaces in the Danish North Sea
Authors: SALOMONSEN INGER , JENSEN KARSTEN ALBiEK
Published: July 2010

Studies of a deep high‐resolution reflection seismic profile through the eastern North Sea basin show that at least four erosional phases have affected the area during the Saalian, Weichselian and Holocene. Foraminiferal investigations of five boreholes make it possible to date the erosional events. When looking at the restricted area of this study, the deep incised valleys appear to have developed during sea‐level fall and lowstand as the Quaternary ice sheets were established. Further erosion took place during the deglaciation of the area and the valleys were further deepened when used as drainage paths. The oldest erosional phase recognized from the seismic profiles is interpreted to be of Saalian age. Two later erosive phases were associated with intra‐Weichselian glacial advances. The uppermost erosive surface represents river valleys at the transition from the Weichselian glacial to the Holocene.
Alpine valley heads on the Antarctic Peninsula
Authors: HAYNES VALERIE M.
Published: July 2010

Landform assemblages may be useful for elucidating glaciological changes in West Antarctica. Numerous nunataks in the Antaretic Peninsula are highly dissected by alpine valley heads (corries, cirque‐headed valleys, etc.). It is believed that these have been cut by wet‐based mountain glaciation before and during the build up of the ice‐sheet. though the smallest ones may have formed later at times when the ice‐sheet was insufficiently thick to submerge them. Dimensions of the features suggest that the main alpine glaciation was in the Miocene. Morphometric analysis of 1663 alpine valley heads has been based on satellite imagery, concentrating on regional variations in frequency, size and orientation. Length of alpine glaciation is believed to be an important control of size. Orientation is believed to have been influenced by palaeoclimate as well as topography. During early, more marginal glaciations poleward and lee‐side sites were occupied by corrie glaciers, with more windward sites being added as glaciation intensified, followed by northerly orientations under more recent polar conditions. Comparisons have also been made with other morphometric studies of corries in Antarctica and elsewhere.
Subglacial to proglacial sediment transition in a shallow ice‐contact lake
Authors: II CHARLES W. ROVEY , BORUCKI MARK K.
Published: July 2010

A complete subglacial to glacial‐lacustrine facies transition is described from a temporary exposure in the Lake Michigan bluffs of southeastern Wisconsin. This transition occurs where a Late Woodfordian terminal moraine intersects the bluff line and grades from basal meltout till to chaotic diamicton to rhythmites over an abrupt 90 m lateral distance. The boundary of the subglacial meltout deposits is marked by an abrupt increase in pebbles and cobbles, which cluster at specific horizons, producing an incipient stratification. Thereafter, the diamicton develops contorted flow structures with progressive segregation into coarse and fine‐grained fractions, ultimately into well‐stratified rhythmites.
Vegetation history of the European Quaternary
Authors: Vorren Karl‐Dag
Published: July 2010

Lang, G. 1994: Quartäre Vrgetationsgeschichte Europas. Methoden und Ergebnisse. Gustav Fischer Verlag, Stuttgart/New York. 462 pp. (177 Figures, 54 Tables, 109 pp. addenda, index lists and references).
The Litorina transgression in the Helsinki region, southern Finland: new evidence from coastal mire deposits
Authors: KORHOLA ATTE
Published: July 2010

Sediment profiles were obtained, from the basal sections of two mire basins located above the highest Litorina shore in the Helsinki region, for pollen, diatom and Cladocera analyses and radiocarbon dating with the aim of exploring the relative sea‐level changes during the Litorina stage of the Baltic Sea. Both profiles provided indications of ‘long‐distance effects’ of the Litorina transgression around 7500–6100 BP, in the form of eutrophication, inundation, increased Pediastrum abundances, declined chydorid diversity and the presence of saline water diatoms. The results support the idea that sea level rose during the Litorina stage in the Helsinki region and suggest that this transgressive event had considerable effects on natural conditions in the coastal ecosystems. The findings contradict earlier accounts of a shore level stillstand during the Littorina stage in the Helsinki district.
The ability of ice‐flow indicators to record complex, historic deglaciation events, Burroughs Glacier, Alaska
Authors: SYVERSON KENT M.
Published: July 2010

Known changes in ice‐flow direction during a 100‐year interval have been used to evaluate how well ice‐flow indicators record complex deglaciation events. At Burroughs Glacier, nunataks emerging from a thinning Neoglacial ice mass and differential ice‐surface lowering caused by calving ice margins have produced major changes in ice‐flow direction sincc 1892. Cross‐cutting striae with angles of divergence of up to 105′ reflect the past range of flow directions in the area. Striae from the oldest flow events are deepest, and striae from some late‐stage flow events are missing. This may be caused by overprinting during late‐stage reversals in the direction of ice movement. The orientation of flutes and surficial bullet boulders reflects the final ice‐flow direction, but boulder orientations are less clustered than flute orientations. Surficial till pebble fabrics are weakly to moderately developed, but till fabrics vary with depth and record ice‐flow direction changes with time.
Major palaeohydrographic changes in Alpine foreland during the Pliocene ‐ Pleistocene
Authors: PETIT CHRISTOPHE , CAMPY MICHEL , CHALINE JEAN , BONVALOT JACQUES
Published: July 2010

The changing palaeogeographical pattern of Alpine deposits across the European forelands can be traced by identifying mineral assemblages and establishing the chronology of Pliocene‐Pleistocene deposits in Alpine foreland. In the late Miocene, the upper courses of the Rhine and the Aar flowed east from the Swiss molasse plain towards the Danube. In the early Pliocene (Brunssumian, 5‐3.2 Ma), these same rivers headed north wards towards the Rhine Graben of Alsace. In the early Reuverian, these streams were captured south of the Rhine Graben by the Doubs. They ceased their northward flow and headed west to feed the Bresse Graben. This phase is dated to the Lower and Middle Reuverian (3.2‐2.6 Ma). From the Upper Reuverian (2.6 Ma) to the present day, the Rhine has adapted approximately its present course towards the North Sea, south to north along the Rhine Graben and across the Rhine Schist Massif to feed the Dutch Grabens. This changing pattern of capture and alteration of the hydrographic system of the upper reaches of the Rhine and the Aar can be explained by local tectonic movements.
A comprehensive and scholarly new book reviewing the Quaternary of the whole of Scandinavia
Authors: CATT JOHN A.
Published: July 2010

Book reviewed in this article:

Donner, J. 1995: The Quaternary History of Scandinavia
Varve‐counting by the annual pattern of diatoms accumulated in the sediment of Big Watab Lake, Minnesota, AD 1837–1990
Authors: CARD VIRGINIA M.
Published: July 2010

The goal of this study was to develop a method for extracting quantitative annual records of diatoms and other microfossils from sediments that are resistant to existing varve‐counting methods because of their variable, complex, or indistinct laminations. Very linely laminated organic sediments from a deep diamictic lake in central Minnesota, USA were collected by freeze‐core, dehydrated by solvent exchange, embedded with epoxy, and petrographically thin‐sectioned. Diatom frustules and pollen grains were counted in contiguous 400 pm microscope fields‐of‐view and used to construct a sediment chronology. The concentration of diatoms in the sediment was cyclic and lowest in sediment deposited during summer. The concentration of pollen in the sediment was also cyclic and sediment deposited during the summer contained the highest concentrations of pollen and the highest percentages of ragweed (Ambrosia spp.) pollen. The sediment chronology that was produced accurately records the onset of regional (c. 1850) and watershed (c. 1880) development, a historic tornadic storm complex (1894), and individual drought years (1932, 1934 & 1935) within the 1930's drought.
Lacustrine sedimentation and tectonics: an example from the Weichselian at Lønstrup Klint, Denmark
Authors: SADOLIN MALENL , PEDERSEN GUNVER KRARUP , PEDERSEN STIC. A. SCHACK
Published: July 2010

Sedimentological analysis of the Weichselian deposits exposed in the coastal cliff section at Lønstrup Klint, northern Jutland, Denmark, demonstrates the presence of four sedimentary units comprising fine‐grained lacustrine and fluvial deposits of the latest Middle Wcichselian. The Lønstrup Klint section also shows an interplay between glaciotectonics and sedimentation. The two lower sedimentary units are separated by an erosional unconformity of pretectonic origin, whereas the upper two units are syntectonic. The glaciotectonic processes reflect the Late Weichselian expansion of the Scandinavian ice cap into northern Jutland. The sedimentary structures indicate high rates of deposition. The area underwent dramatic palaeogeographic changes from deep lake to proglacial fluvial plain in a time‐span of a few thousand years.
Late Weichselian ostracod assemblages from the southern Kattegat, Scandinavia: a palaeoenvironmental study
Authors: MAJORAN STEFAN , NORDBERG KJELL
Published: July 2010

The ostracods in three vibro cores (representing the time between c. 13000 and 12000 BP) from southern Kattegat were studied to further elucidate palaeoenvironmental conditjons in an area interpreted to be influenced by a Late Weichselian drainage of the Baltic Ice Lake via the Öresund Strait. This time represents an extremely important phase of the deglaciation of the northern hemisphere. It is characterized by rapid climatic change and enormous amounts of meltwater that are drained into the ocean. The ostracod assemblages identified are characterized by a peculiar mixture of marine (arctic and temperate) and freshwater species believed to characterize environments ranging from the tidal zone of an outer estuary (or delta) to fully marine sublittoral conditions in a subarctic climate. Dominant species display autochthonous population structures typical of in situ elements of such environments. Indications of very shallow conditions are, however, difficult to reconcile with palaeobathymetrical inferences from earlier studies of shore‐level displacements. It is, therefore, possible that the present assemblages are mainly death assemblages deposited offshore by postmortem meltwater discharge. Rare pre‐Quaternary ostracods similar to Mesozoic species previously reported from the Öresund Strait (drill holes) and the Swedish west coast may have been redeposited by outflowing meltwater.
Postglacial relative sea‐level history: sediment and diatom records of emerged coastal lakes, north‐central Kola Peninsula, Russia
Authors: SNYDER JEFFREY A. , FORMAN STEVEN L. , MODE WILLIAM N. , TARASOV GENNADY A.
Published: July 2010

Sediment cores recovered from four emerged lakes (54, 41, 22, and 7 m a.s.l.) provide new data on the deglaciation and relative sea‐level history of the Murman coast, Kola Peninsula. The transition from marine to lacustrine sediment is identified in the cores by analysis of sediment physical properties and diatom assemblages. Fourteen AMS‐radiocarbon ages on organic macrofossils isolated from core sediment provide chronology for the records. Basal ages from two of the cores indicate deglaciation of the area prior to 11000 BP. Radiocarbon ages associated with the marine‐lacustrine sediment transition in the cores further constrain the emergence history of the area. The prominent late‐glacial shoreline on the Murman coast (48 m a.s.l.) is dated to c. 10500–10300 BP, the emergence ages of lake basins 54 and 41 m a.s.l. Glaciofluvial terraces graded to this shore level indicate remnant glaciers on the north‐central Kola Peninsula during the Younger Dryas.
Palaeoecological analysis of mammalian faunas and environmental evolution in the South of France during the Pleistocene
Authors: MONTUIRE SOPHIE , DESCLAUX EMMANUEL
Published: July 2010

The study of mammalian faunas has contributed widely to the knowledge of palaeoenvironments during the Quaternary. The cenogram method, a graphical representation of the mammalian community structure, permits the reconstruction of the environments and the inference of the climatic conditions. This method has the advantage of taking into account all the mammals present in a fossil locality. Applied on several faunas of the South of France, this method shows different phases in the climatic and environmental changes during the Pleistocene. From the setting‐up of glacial cycles in the Pleistocene, the conditions become colder and there is an alternation between a rather closed environment during the interglacial periods and a more open landscape during the coldest periods of the Pleistocene.
Stratigraphy, palaeomagnetism and age of volcanics in the upper regions of ÞJórsárdalur valley, central southern Iceland
Authors: KRISTJÁNSSON LEÓ , DUNCAN ROBERT A. , GUÐMUNDSSON ÁGÚST
Published: July 2010

The ‘Hreppar Formation’ of southern Iceland is a succession mostly composed of basalt lavas and clastic material, with a slight anticlinal structure. It may represent a crustal fragment left in place by eastwards movement of the active spreading zone during the past 2–3 Ma. Evidence of several cycles of alternating glacial‐interglacial conditions is seen in this succession. The first systematic stratigraphic study within the succession which is combined with K‐Ar age determinations and laboratory palaeomagnetic measurements on oriented cores has yielded encouraging results. The age determinations confirm earlier estimates by Icelandic geologists on the age range spanned by the Hreppar succession. Units from the Jaramillo geomagnetic subchron are present in its upper part, and at least one polarity reversal event in the lower Matuyama chron is also recorded.
Comparative study of striations and basal till clast fabrics, Malpeque—Bedeque region, Prince Edward Island, Canada
Authors: CATTO NORM R.
Published: July 2010

Coastal erosion has resulted in exposure of a succession of basal till deposits and striation localities along the Malpeque and Bedeque Bays, PEI, Canada, permitting repetitive determinations of clast fabrics and investigation of recently exhumed striations. Striations indicate initial eastward ice flow, followed by a second glacial event with flow towards the south and southwest from the Gulf of St. Lawrence. The degree of local inconsistency and the variations with striation assemblages indicate that the orientations of individual striations cannot be regarded as ‘absolute’ indicators of ice flow directions. Diamictons identified as basal tills using sedimentological criteria have clast fabrics typical of basal till deposition. Local deviations of fabric trend within individual outcrops are common. A comparative analysis of the data obtained from striation and clast fabric orientations indicates that the ice flow directions independently suggested by each are in general agreement. Differences are present between the orientations of striations and clast fabrics at individual sites. The orientations of the fabrics lie within 20° of the modal striation orientations in only 28% of the cases, and the median deviation between the suggested ice flow directions was 29°. In 40%, of the cases, the azimuth deviation between the two methods exceeded 40°, and the maximum deviation recorded was 84°. At many sites, the deviations are so severe as to potentially result in the misinterpretation of the modal ice flow direction, based on the use of either striation orientation or clast fabric in isolation. Variations in glacial flow can readily produce striations and clast fabrics which record different phases of glacial activity associated with the same glacial event at an individual site.
The Kregnes moraine in Gauldalen, west‐central Norway: anatomy of a Younger Dryas proglacial delta in a palaeofjord basin*
Authors: NEMEC W. , LφNNE IDA , BLIKRA LARS H.
Published: July 2010

The Kregnes “moraine” ridge in Gauldalen, a north‐trending valley south of Trondheim, is a Gilbert‐type delta formed at a Younger Dryas glacier terminus. The gravelly delta consists of a north‐dipping foreset, 150 m thick, comprised of turbidites, debrisflow beds and debrisfall deposits. The bottomset consists of turbiditic sand and mud layers. The topset, 2–3 m thick, is a braided‐river alluvium with local beach deposits, matching the marine limit of 175 m a.s.l. The fjord‐wide delta front had an extent of 3 km and prograded over a distance of 1.5 km, in probably less than 100 years, with the delta toe climbing by 50 m against the basin's rapidly aggrading muddy floor. The delta advanced through the alternating episodes of its toe aggradation and progradation, related to the increases and decreases of the delta‐slope gradient. Slope steepening led to intense sediment sloughing by chutes and occasional large‐scale failures. The fjord's wave fetch was low and the wave base no deeper than 1.5‐2 m, but strong storm waves occasionally reworked the delta front to a depth of 6 m. Glacitectonic deformation was limited to the system's upfjord end. Allostratigraphic analysis suggests that the proglacial system commenced its development as an ice‐contact submarine fan that was deformed, quickly aggraded to the sea surface and turned into an ice‐contact delta, which further evolved into the large glaciofluvial delta. The Kregnes ridge represents an episode of the ice‐front re‐advance due to climatic deterioration and is tentatively correlated with the Hoklingen substage.
AMS 14C measurements and macrofossil analyses of a varved sequence near Pudozh, eastern Karelia, NW Russia
Authors: WOHLFARTH BARBARA , BENNIKE OLE , BRUNNBERG LARS , DEMEDOV IGOR , POSSNERT GÖRAN , VYAHIREV SERGEI
Published: July 2010

The laminated sediments at Pudozh in eastern Karelia are generally assumed to have been deposited between 13 000 and 16 000 14C yr BP and have been used to date the recession of the active ice margin. However, 17 AMS 14C measurements performed on terrestrial plant macrofossils contained in these sediments show that deposition began during the late Allerφd, when the ice margin had already receded to the northern part of Lake Onega. Based on an age model, we assume that the 1933‐year‐long varved sequence covers the time period between c. 12 900 and 11 000 calendar years BP. During this period, which comprises the later part of the Late Weichselian and the early Holocene, the local vegetation consisted of open, tree‐less dwarf shrub heaths. Increased soil erosion may have occurred before 12 550 calendar years BP.
Auto‐correlation analysis in search of short‐term patterns in varve data from sediments of Lake Gościā, Poland
Authors: YOUNG RAYMOND , WALANUS ADAM , GOSLAR TOMASZ
Published: July 2010

The annually laminated, or varved, sediments of Lake Gościź, Poland, cover the last c. 12900 years, from Late Allerød up to the present. We have analysed the thickness of 1912 varves in this time‐series by means of auto‐correlation analysis, in the hope of obtaining information on patterns in past climate, for example patterns of 11 years, which might indicate a relation with solar activity. We analysed the total varve thickness and the thickness of the summer and the winter layer. Two single‐bootstrap experiments confirmed the validity of the methods in general, but they indicated that the moving‐window technique with overlapping windows hampered the assessment of statistical significance. Three global significance assessment procedures, taking into account the total number of auto‐correlation coefficients (ACs) that is tested, showed significance of the ACs only at a lag of one year and only for the winter layer and the total varve. This auto‐correlation with the preceding year may be explained by a factor internal to the lake, for instance some depositional mechanism. We found no indication of a relation between varve formation and the sun‐spot cycle.
New discoveries of the Vedde Ash in southern Sweden and Scotland
Authors: WASTEGÅRD STEFAN , TURNEY CHRIS S. M. , LOWE J. JOHN , ROBERTS STEPHEN J.
Published: July 2010

The Vedde Ash (c. 10 300 14C BP) provides a key time‐parallel marker horizon within the Younger Dryas chronozone or GS‐1 event of the GRIP stratigraphy. Until recently, the known distribution of wind‐blown Vedde Ash outside Iceland was restricted to the west coast of Norway, off‐shore sequences close to the Outer Hebrides and the Greenland summit GRIP ice core. The first discoveries of the Vedde Ash in Scotland were reported in 1997, following the development of a new technique for extracting rhyolitic micro‐tephra particles from minerogenic deposits. Here we report on the discovery of the Vedde Ash at additional sites in Scotland and at sites in southern Sweden. The concentration of tephra particles in sediments is highest in sites in western Norway, but is also relatively high in sites in southwestern Sweden, suggesting that the main ash cloud travelled eastwards from its volcanic source of Katla, in southern Iceland. Electron microprobe analyses do not indicate any clear geochemical evolution within the samples reported here.
Role of climate in the rise and fall of Neolithic cultures on the Yangtze Delta
Authors: YU SHIYONG , ZHU CHENG , SONG JIAN , QU WEIZHENG
Published: July 2010

Climatic changes in the Yangtze Delta have played an important role in the emergence, persistence and collapse of civilization. Archaeological excavations in the region over many years have demonstrated that there are several layers of fine sand or organic mud that interrupt the consecutive culture strata in a number of Neolithic culture sites. Continuous biostratigraphical and sedimentological records from the Maqiao cultural site, Shanghai, suggest that the fine sand and organic mud units resulted from expansion of water bodies both by sea‐level fluctuations and from increased flooding during cold and humid episodes of Holocene climates. The absence of human settlement from 7240 BP to 5320 BP in the region was mainly caused by higher sea levels resulting from a warm and humid climate. The Neolithic cultures developed under conditions of lower and more stable sea level as well as warmer and dryer climates between about 4410 BP and 3250 BP. A flood‐induced lake expansion interrupted the civilization in the region at about 4200 BP. Later, higher water tables and expansion of lakes between 3250 BP and AD 618 under a cold and moist climate temporarily terminated settlement on the delta. Later, during the Tang Dynasty, beginning at about AD 618, the region again became suitable for human settlement under conditions of more favourable climate and lower water tables.
Rates of Holocene isostatic uplift and relative sea‐level lowering of the Baltic in SW Finland based on studies of isolation contacts
Authors: ERONEN MATTI , GLUCKERT GUNNAR , HATAKKA LASSI , PLASSCHE ORSON VAN DE , PLICHT JOHANNES VAN DER , RANTALA PASI
Published: July 2010

Southwestern Finland was covered by the Weichselian ice sheet and experienced rapid glacio‐isostati c rebound after early Holocene deglaciation. The present mean overall apparent uplift rate is of the order of 4–5 mm/yr, but immediately after deglaciation the rate of crustal rebound was several times higher. Concurrently with land uplift, relative sea level in the Baltic basin during the past more than 8000 years was also strongly affected by the eustatic changes in sea level. There is ample evidence from earlier studies that during the early Litorina Sea stage on the southeastern coast of Finland around 7000 yr BP (7800 cal. yr BP), the rise in sea level exceeded the rate of land uplift, resulting in a short‐lived transgression. Because of a higher rate of uplift, the transgression was even more short‐lived or of negligible magnitude in the southwestern part of coastal Finland, but even in this latter case a slowing down in the rate of regression can still be detected. We used evidence from isolation basins to obtain a set of 71 14C dates, and over 30 new sea‐level index points. The age‐elevation data, obtained from lakes in two different areas and located between c. 64 m and 1.5 m above present sea level, display a high degree of internal consistency. This suggests that the dates are reliable, even though most of them were based on bulk sediment samples. The two relative sea‐level curves confirm the established model of relatively gradually decreasing rates of relative sea‐level lowering since c. 6100 yr BP (7000 cal. yr BP) and clearly indicate that the more northerly of the two study areas experienced the higher rate of glacio‐isostati c recovery. In the southerly study area, changes in diatom assemblages and lithostratigraphy suggest that during the early Litorina Sea stage (8300–7600 cal. yr BP) eustatic sea‐level rise exceeded land uplift for hundreds of years. Evidence for this transgressio n was discovered in a lake with a basin threshold at an elevation of 41 m above sea level, which is markedly higher than any previously known site with evidence for the Litorina transgression in Finland. We also discuss evidence for subsequent short‐term fluctuations superimposed on the main trends of relative sea‐level changes.