bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal and spatial sedimentation rate variabilities in the eastern Gotland Basin, the Baltic Sea
Authors: CHRISTIANSEN CHRISTIAN , KUNZENDORF HELMAR , EMEIS KAY‐CHRISTIAN , ENDLER RUDOLF , STRUCK ULRICH , NEUMANN THOMAS , SIVKOV VADIM
Published: July 2010

The present study examines sedimentation rates in the eastern Gotland Basin using a variety of methods that reveal considerable heterogeneity in the rates, both spatially and temporally. High‐resolution seismic recordings and correlation with long sediment cores indicate increased thickness of strata and higher sedimentation rates (0.75 mm a‐1) in the eastern part of the basin than in the western part (0.23 mm a‐1) since the Littorina transgression some 8000 14C years BP. This difference is apparently a consequence of a counterclockwis e near‐bottom circulation in the basin with periodically high current speeds that cause winnowing on the steep SE slope of the basin and differential settling of sediments in areas of low current speeds. On shorter time scales, recent sediment accumulation rates based on radiometric dating (210Pb) are in general twice as high as those observed 25 years ago using the same method. The higher modern rates, compared to those of the 1970s, may partly be due to increased eutrophication, as more carbon is buried in the sediment, and partly due to increased erosion in shallow water areas. However, strong lateral variations are evident. The average sediment accumulation rates vary between 119 and 340 gm‐2 a‐1 (corresponding to sedimentation rates of 2.1–2.5 mm a‐1) in the deepest part of the basin. Very high rates (6100 g m‐2 a‐1, corresponding to sedimentation rates of 30 mm a‐1) are observed on an intraslope basin site (offshore Latvia) at a water depth of only 70 m. The radiometrically determined sediment accumulation rates are up to three times higher than those estimated from average water column concentrations of suspended matter and from sediment trap flux rates. The discrepancy suggests that sedimentation in the deep basin may have a substantial contribution from near‐bottom lateral transport.
Regressions and transgressions of the Baltic basin reflected by a new high‐resolution deglacial and postglacial lithostratigraphy for Arkona Basin sediments (western Baltic Sea)
Authors: MOROS MATTHIAS , LEMKE WOLFRAM , KUIJPERS ANTOON , ENDLER RUDOLF , JENSEN JØRN BO , BENNIKE OLE , GINGELE FRANZ
Published: July 2010

Seismoacoustic profiles from the Arkona Basin show a late Pleistocene and Holocene succession of several distinct reflectors. The physical, sedimentological, mineralogical and geochemical properties of more than 30 sediment cores were analysed in order to assign these reflectors to specific sedimentary discontinuity layers. Additionally, AMS 14C data and biostratigraphic information were gathered. Based on this multi‐proxy approach, seven lithostratigraphic units (AI, AII, B to F) were distinguished. These consist of fine‐grained clay, silt and mud, and are separated from each other by thin basin‐wide traceable sandy layers (Sab‐Sef). The most sensitive parameter to mark the lithostratigraphic boundaries is the weight percentage of the grain‐size fraction >63μm. In addition, some of the quartz‐grain‐dominated sandy layers cause the strong reflection lines recorded in seismoacoustic profiles. The sandy layers are interpreted to reflect enhanced hydrodynamic energy induced by episodes of basin‐wide water‐level low‐stand conditions. These low stands resulted from water‐level drops that occurred frequently during the Baltic Sea's history and presumably affected the entire Baltic basin. The thick fine‐grained units AI, AII to F, in which coarser material is absent, represent water‐level high‐stands. We conclude that the units AI and AII are Baltic Ice Lake sediments deposited before and after the Billingen‐1 regression, respectively. We assign the most prominent sandy layer Sab to the final drainage of the Baltic Ice Lake (Billingen‐2), whereas the sandy layers between units B, C., D and E are related to the Yoldia Sea and Ancylus Lake regressions of the Baltic Sea's history. The uppermost fine‐grained unit F with its high organic carbon content contains marine sediments deposited after the Littorina Transgression. The macroscopically well‐visible sediment colour change from reddish/brown‐to‐grey, previously interpreted as a regional stratigraphic boundary, varies from core to core. It has been shown by our new data that this colour change has a diagenetic origin, and thus does not represent a stratigraphic boundary. Previous subdivisions therefore have to be revised.
Shell gravel deposits on the Åland Islands, southwestern Finland, with special reference to the molluscan assemblages
Authors: CARLSSON RALF
Published: July 2010

Twenty‐six shell gravel sites at elevations between 3 and 35 m a.s.l. were found on the Åland Islands. The faunal composition was determined on 14 of these locations and Mytilus edulis and Macoma balthica were found everywhere. Another common species was Hydrobia ulvae, while H. ventrosa, Littorina saxatilis and Cerastoderma glaucum were more sporadic. This species assemblage implies that the salinity of the area was about 10C when the animals lived there. The deposits on the N‐NE hilltops generally have southerly to westerly aspects, while those of the south‐central hilltops are easterly. On the basis of a 14C‐dated stratified deposit it is suggested that each deposit was formed during a relatively short period of time. As a hilltop emerged from the sea, glacial debris was flushed down. Shell‐bearing molluscs colonized the bare rock surface and were flushed down and formed the shell gravel deposit as the shoreline displacement continued. At a later stage, as the more concave part of the hilltop was subject to wave action, erosion was weaker and the shell gravel deposit was covered by beach sand. Since the hills may be of different elevation, it is concluded that trying to date ancient shorelines from shell gravel deposits is not justified, as each deposit originates from the hill with which it is associated.
Evidence of the final drainage of the Baltic Ice Lake and the brackish phase of the Yoldia Sea in glacial varves from the Baltic Sea
Authors: ANDRÉN THOMAS , LINDEBERG GREGER , ANDRÉN ELINOR
Published: July 2010

A clay‐varve chronology based on 14 cross‐correlated varve graphs from the Baltic Sea and a mean varve thickness curve has been constructed. This chronology is correlated with the Swedish Time Scale and covers the time span 11 530 to 10250 varve years BP. Two cores have been analysed for grain size, chemistry, content of diatoms and changes in colour by digital colour analysis. The final drainage of the Baltic Ice Lake is dated to c. 10800 varve years BP and registered in the cores analysed as a decrease in the content of clay. This event can be correlated with atmospheric Δ14C content and might have resulted in an increase in these values recorded between 11 565 and 11 545 years BP. The results of the correlation between the varve chronology from the Baltic Sea, the Greenland GRIP ice core and the atmospheric Δ14C record indicate that c. 760 years are missing in the Swedish Time Scale in the part younger than c. 10250 varve years BP. A change in colour from a brownish to grey varved glacial clay recorded c. 10770 varve years BP is found to be the result of oxygen deficiency due to an increase in the rate of sedimentation in the early Preboreal. The first brackish influence is recorded c. 10540 varve years BP in the northwestern Baltic Sea and some 90 years later in the eastern Gotland Basin.
Interpreting the Tyrrhenocythere (Ostracoda) signal from Palaeolake Kopais, central Greece
Authors: GRIFFITHS SUSAN J. , GRIFFITHS HUW I. , ALTINSAÇLI SELÇUK , TZEDAKIS CHRONIS
Published: July 2010

A long Late Quaternary sedimentary record from Lake Kopais, central Greece, has yielded assemblages of ostracod shells amongst which are discrete horizons of Tyrrhenocythere donetziensis. To date, this species has been little recorded in the region. We provide details of the species' occurrence and ecology and examine its validity as a palaeoecological and palaeobiogeographical marker. Although Lake Kopais has been artificially drained, a continuous record of climate change extending well beyond the onset of the last glacial has been recorded in calcareous sediments taken from the deepest part of the basin (core K93). Ostracod assemblages occur through most of the core, however, T. donetziensis is present only in the lower part. The evidence from this study of core K93 suggests that warm, humid conditions in the catchment may be one of the limiting factors for the occurrence of this particular species of Tyrrhenocythere.
Late Quaternary history of Washington Land, North Greenland
Authors: BENNIKE OLE
Published: July 2010

During the last glacial stage, Washington Land in western North Greenland was probably completely inundated by the Greenland Ice Sheet. The oldest shell dates from raised marine deposits that provide minimum ages for the last deglaciation are 9300 cal. yr BP (northern Washington Land) and 7600 cal. yr BP (SW Washington Land). These dates indicate that Washington Land, which borders the central part of Nares Strait separating Greenland from Ellesmere Island in Canada, did not become free of glacier ice until well into the Holocene. The elevation of the marine limit falls from 110 m a.s.l. in the north to 60 m a.s.l. in the southwest. The recession was followed by readvance of glaciers in the late Holocene, and the youngest shell date from Neoglacial lateral moraines north of Humboldt Gletscher is 600 cal. yr BP. Since the Neoglacial maximum, probably around 100 years ago, glaciers have receded. The Holocene marine assemblages comprise a few southern extralimital records, notably ofChlamys islandicadated to 7300 cal. yr BP. Musk ox and reindeer disappeared from Washington Land recently, perhaps in connection with the cold period that culminated about 100 years ago.
Holocene history of Lake Soldatskoje (Kola Peninsula, Russia) inferred from sedimentary diatom assemblages
Authors: GRÖNLUND TUULIKKI , KAUPPILA TOMMI
Published: July 2010

A sediment core from Lake Soldatskoje, a small tundra lake located in the northern coastal area of the Kola Peninsula and surrounded by numerous archaeological dwelling sites, was analysed for diatom species. The core covers the entire Holocene, i.e. 10000 radiocarbon years. The diatom record has similarities with studies made earlier from tundra lakes of northern Russia and from Arctic lakes in general. The genus Fragilaria was dominant and many other small, benthic, nordic, cold‐water diatom species typical of Arctic lakes were common, including Achnanthes minutissima Kützing, A. pusilla (Grunow) De Toni, Cyclotella tripartita Håkansson and Navicula absoluta Hustedt. Multivariable ordinations were used to characterize the changes in the diatom flora. Diatom‐based pH and total phosphorus inferences indicate that the lake has become progressively more acidic and poorer in nutrients. Disturbances in the diatom stratigraphy of Lake Soldatskoje around 4000–5500 14C yr BP may be related to human activity.
Optically stimulated luminescence dating of fluvial deposits: a review
Authors: WALLINGA JAKOB
Published: July 2010

Optically Stimulated Luminescence (OSL) dating allows age determination of sediments deposited during the last glacial‐interglacial cycle. This relatively new technique therefore enables chronological frameworks to be established for fluvial deposits that often cannot be dated by other means. The OSL signal of quartz and feldspar minerals is reset by light exposure during fluvial transport, and builds up as a result of ionizing radiation after burial of the minerals. Incomplete resetting of the OSL signal because of inadequate light exposure in the fluvial environment can result in age overestimations, especially for relatively young samples. Methods used for the detection of incomplete resetting, or poor bleaching, are reviewed. It is argued that technique s measuring the OSL signal from small subsamples (aliquots) are most promising for detecting poor bleaching and for obtaining the true age for a sample in which not all grains had their OSL signal completely removed at deposition. Quartz should be the mineral of choice, because it has been shown to yield the most reliable results and because its OSL signal is more rapidly reset than that of feldspar. Aliquot size should be small, with aliquots ideally consisting of a single grain of quartz for samples in which the majority of grains are poorly bleached. Using single‐aliquot dating of coarse‐grain quartz, age offsets between zero and a few thousand years have been found for modern fluvial deposits. The validity of single‐aliquot quartz OSL dating has been demonstrated by application to known‐age samples, but for the older age range (>˜13 ka) further proof of the accuracy of the method is essential. The application of quartz OSL dating to investigations of fluvial deposits opens a new realm of possibilities to be explored, as is highlighted by some examples of geological applications.
Subfossil littoral Cladocera as indicators of brackish‐water Littorina transgression of the Baltic Basin in a small lake in Finland
Authors: SARMAJA‐KORJONEN KAARINA , HYVÄRINEN HANNU
Published: July 2010

The study aimed to investigat e the value of freshwater littoral Cladocera (chydorids, Ophryoxu s gracili s and Sida crystallina) in stratigraphical studies of shore displacement of the Baltic Sea. Diatoms and Cladocera were analysed from a sediment core from Lake Ruokolampi (S Finland, 60°34'N, 27°26'E), where a brackish‐water Baltic transgression (Littorina Sea) is clearly expressed by changes in lithology. The diatom flora indicates a development of the waterbody from an Ancylus Lake bay to a small lake that was subject to a brackish Littorina transgressio n followed by another small‐lake stage. There was a rich chydorid fauna in the Ancylus Lake bay and the following small lake. Littoral Cladoceran diversity fell sharply at the onset of the brackish transgression; however, three species (Alona rectangula, Alona affinis and Chydorus sphaericus s.l.) appear to have been tolerant of the saline conditions. Concentrations of all species rose rapidly after the transgression. Littoral Cladocera appear to react to the inflow of brackish water as sensitively as the diatoms and may provide a valuable additional method for pinpointing Baltic Sea transgression and isolation events, especially in cases where the diatom and biostratigraphical evidence is not as clear as in the Ruokolampi sequence.
Boulder‐gravel hummocks and wavy basal till contacts: products of subglacial meltwater flow beneath the Saginaw Lobe, south‐central Michigan, USA
Authors: FISHER TIMOTHY G. , TAYLOR LAWRENCE D. , JOL HARRY M.
Published: July 2010

Hummocky terrain composed of boulder gravel and a wavy contact between stratified till and sand are described and explained as products of subglacial meltwater activity beneath the Saginaw Lobe of the Laurentide Ice Sheet in south‐central Michigan. Exposures and geophysical investigations of hummocky terrain in a tunnel channel reveal that hummocks (˜100m diameter) are glaciofluvial bedforms with a supraglacial melt‐out till or till flow veneer. The hummocky terrain is interpreted as a subglacial glaciofluvial landscape rather than one of stagnant ice processes commonly assumed for hummocky landscapes. Sandy bedforms at another site are in‐phase with a wavy contact at the base of a stratified till exposed for 50m along the margin of a tunnel channel. The 0.4m thick stratified till is overlain by up to 5m of compact, pebble‐rich, sandy subglacial melt‐out till. The contact between the till and sand has a wave form with a 0.5m amplitude and 3‐5m wavelength. Bedding within the stratified till, sandy bedforms and melt‐out till are mostly in‐phase with each other. Clasts from the overlying stratified till penetrate and deform the underlying sand recording recoupling of the ice to its bed. Ice ripples cut into the base of river ice have a similar morphology and are considered analogs for cavities cut into the base of the glacier and subsequently filled with sand. Subglacial meltwater activity was not coeval at each study site, indicating that subglacial meltwater played important roles in the evolution of the subglacial environment beneath the Saginaw Lobe at different times.
A local clay‐varve chronology and proglacial sedimentary environment in glacial Lake Peipsi, eastern Estonia
Authors: HANG TIIT
Published: July 2010

Ten cores consisting of varved clay from the northern part of Lake Peipsi in eastern Estonia have been correlated using varve thickness variations and specific marker varves into a 375‐year floating varve chronology. Continuous sedimentation during gradual ice recession is concluded from a clear transition from proximal to distal varves. Cyclic variations in varve thickness are caused mainly by thickness changes of clayey winter layers. This is interpreted to indicate increased influx of finer material due to faster melting of the glacier. The cyclic pattern of thickness change is explained by alternating periods of increased and decreased melting of the ice. Simultaneous accumulation of varved clay in glacial Lake Peipsi and in the Luga and Neva basins of Russia is concluded from the good visual correlation between the mean varve thickness diagrams for the three chronologies. Because the varve chronologies from northwestern Russia have been tentatively correlated to the Swedish varve chronology, the timing of the clay accumulation in glacial Lake Peipsi is placed between c. 13500 and 13100 varve years BP.
Correlation of stadial and interstadial events in the south Swedish glacial varves with the GRIP oxygen isotope record
Authors: RINGBERG BERTIL , BJÖRCK JONAS , HANG TIIT
Published: July 2010

A number of correlated varve sequences from the local varve chronology in southeastern Sweden have been selected to make a 1040 varve years long mean varve thickness curve. Pollen analyses were carried out over an interval of 373 varve years in the northern part of the study area. The pollen stratigraphical data have been divided into local pollen assemblage zones which have been correlated with the radiocarbon‐dated regional pollen assemblage zones. Based on variations in herb and tree pollen content of the analysed varve sequences, it has been possible to identify well‐documented lateglacial pollen zones for southern Sweden, i.e. the Bölling interstadial (GI‐1e), the Older Dryas cold event (GI‐1d) and the early part of the Alleröd interstadial (GI‐1c). The event stratigraphy in this study, based on varying varve thicknesses and the composition of the pollen flora in the varves, has been correlated with the oxygen isotope stratigraphy of the GRIP ice‐core on Greenland between 13600 and 14400 GRIP ice‐core years BP. It is concluded that five decadal warm events and one centennial warm event (15–60 and 100 varve years long, respectively) occur in the clay varve record along with one centennial cold event (150 varve years long), the Older Dryas (GI‐1d).
Lateglacial landform associations at Jæren (SW Norway) and their glaci‐dynamic implications
Authors: RAUNHOLM STÅLE , SEJRUP HANS PETTER , LARSEN EILIV
Published: July 2010

The Jæren lowland is located on the southwestern coast of Norway between a mountainous region in the east and the offshore Norwegian Channel in the west. During the Last Glacial Maximum, Jæren was in an intermediate position between an ice stream following the Norwegian Channel northwards, and westward flowing inland ice. The dynamic behaviour of the inland ice and the interaction with the ice stream are examined by means of geomorphological analysis of digital terrain models and sedimentological investigations. SW‐trending drumlins were formed at Jæren below tributary ice from the inland, feeding into the Norwegian Channel Ice Stream. The presence of Rogen moraine in the central part of Jæren indicates a frozen substratum prior to their formation, and this suggests a transition to cold‐based ice between the tributaries. The deglaciation of the Norwegian Channel at about 15 ka BP resulted in an unstable ice front for the inland ice sheet. The formation of Rogen moraine may be explained by a dynamic advance resulting in extensional flow and fracturing of the frozen substratum between the tributaries. The dynamic advance was followed by an early deglaciation of the coastal areas as evidenced by shallow marine sediments. Deformation of the shallow marine sand indicates a glacial readvance through the valleys formerly acting as tributaries to the ice stream.
Signature and timing of the Kattegat Ice Stream: onset of the Last Glacial Maximum sequence at the southwestern margin of the Scandinavian Ice Sheet
Authors: HOUMARK‐NIELSEN MICHAEL
Published: July 2010

At the end of the Middle Weichselian (30–25 ka BP) a glacier advance from southern Norway, termed the Kattegat Ice Stream, covered northern Denmark, the Kattegat Sea floor and the Swedish West Coast during onset of the Last Glacial Maximum (LGM) at the southwest margin of the Scandinavian Ice Sheet. The lithostratigraphic unit deposited by the ice stream is the till of the Kattegat Formation (Kattegat till). Because morphological features have been erased by later glacial events, stratigraphic control and timing are decisive. The former ice stream is identified by the dispersal of Oslo indicator erratics from southern Norway and by glaciodynamic structures combined with glaciotectonic deformation of subtill sediments. Ice movement was generally from northerly directions and the flow pattern is fan‐shaped in marginal areas. To the east, the Kattegat Ice Stream was flanked by passive glaciers in southern Sweden and its distribution was probably governed by the presence of low permeability and highly deformable marine and lacustrine deposits. When glaciers from southern Norway blocked the Norwegian Channel, former marine basins in the Skagerrak and Kattegat experienced glaciolacustrine conditions around 31–29 ka BP. The Kattegat Ice Stream became active some time between 29 ka BP and 26 ka BP, when glaciers from the Oslo region penetrated deep into the shallow depression occupied by the Kattegat Ice Lake. Deglaciation and an interlude with periglacial and glaciolacustrine sedimentation lasted until c. 24–22 ka BP and were succeeded by the Main Glacier Advance from central Sweden reaching the limit of Late Weichselian glaciations in Denmark around 22–20 ka BP, the peak of the LGM. This was followed by deglaciation and marine inundation in the Kattegat and Skagerrak around 17 ka BP.
Windpolished boulders and bedrock in the Scottish Highlands: evidence and implications of Late Devensian wind activity
Authors: CHRISTIANSEN HANNE HVIDTFELDT
Published: July 2010

The present day maritime climate of Scotland is primarily characterized by strong winds which, in very exposed sites, lead to modern windpolish of rock surfaces. The widespread existence of in situ relict windpolished boulders and bedrock surfaces in Scotland has enabled a reconstruction of prevalent Late Devensian (Late Weichselian) including Loch Lomond Stadial (Younger Dryas) palaeo‐wind directions. Previous reconstructions of palaeo‐wind directions have been indirect and based mainly on the distribution of aeolian sediments and former glaciers. Observations of relict windpolished microforms and their distribution on boulders and bedrock outcrops on various rock types at 55 sites in different parts of the Scottish Highlands have been used to establish a palaeo‐wind map for the area. The reconstruction indicates two sets of dominating wind directions, one between SE and SW and one between NW and N. The maximum age of the windpolish is 16–10 cal. ka BP, but most of it presumably developed during the Loch Lomond Stadial 13–12 cal. ka BP, inferred from the distribution of windpolish sites in relation to the deglaciation chronology and establishment of vegetation.
Climate change and ‘anomalous' glacier fluctuations: the southwest outlets of Mrdalsjökull, Iceland
Authors: CASELY ANDREW F. , DUGMORE ANDREW J.
Published: July 2010

Evidence of past glacier fluctuations is valuable palaeoenvironmental data, but determining their relationship to climatic change is sometimes complex because of differing glacier sensitivities and patterns of response. In Iceland, a diverse range of glaciation creates changing geographical patterns of response to climatic changes. The outlet glaciers of the Márdalsjökull ice cap in southern Iceland have produced detailed, but differing, records of change. For a key southwestern sector of the ice cap, we specifically searched for evidence equivalent to the c. 4500 BP, c. 3100 BP and c. 1200 BP advances of Sólheimajökull reported earlier. A combination of geomorphological mapping and dating by tephrochronology and lichenometry was used to constrain the glacier advances and determine the relative magnitude of Neoglacial glacier episodes. This is a key step towards creating a record of the changes for the entire ice cap. Major glacier advances c. 4500–1000 BP previously identified on the southern margin of Márdalsjökull are shown not to have occurred in this sector, where Neoglacial maxima occur post‐1755 AD.
The Buzzard's Roost and Eustis mollusc sequences: comparison between the paleoenvironments of two sites in the Wisconsinan loess of Nebraska, USA
Authors: ROSSIGNOL JULIEN , MOINE OLIVIER , ROUSSEAU DENIS‐DIDIER
Published: July 2010

We investigated the Upper Pleistocene mollusc sequence in the loess deposit of Buzzard's Roost, Nebraska, and compared the results with those obtained for Eustis, 50 km to the west. Both sequences show similarities in: (i) stratigraphy and magnetic susceptibility implying identical fluctuations in loess deposition, (ii) biostratigraphy which indicates a succession of cold‐and‐moist to cold‐and‐dry conditions, and (iii) an increasing trend in mollusc abundance and diversity of species characterizing a climatic and/or environmental improvement. We interpret the variations in both sequences as related to the advance of the James and Des Moines ice lobes towards both sites, which was synchronous with the retreat of the Laurentide Ice Sheet. The occurrence of hygrophilous species in the mollusc record, from the upper sequences of Buzzard's Roost, suggests a moister environment than in Eustis. Our preliminary comparison of both malacological sequences suggests that regional or local, rather than global, influence prevailed over the Great Plains between 20 and 12 kyr BP.
Reconstruction of late Quaternary sea‐level change in southwestern British Columbia from sediments in isolation basins
Authors: HUTCHINSON IAN , JAMES THOMAS S. , CLAGUE JOHN J. , BARRIE J. VAUGHN , CONWAY KIM W.
Published: July 2010

Bracketing ages on marine—freshwater transitions in isolation basins extending from sea level to 100 m elevation on Lasqueti Island, and data from shallow marine cores and outcrops on eastern Vancouver Island, constrain late Pleistocene and Holocene sea‐level change in the central Strait of Georgia. Relative sea level fell from 150 m elevation to about —15 m from 14000 cal. yr BP to 11 500 cal. yr BP. Basins at higher elevations exhibit abrupt changes in diatom assemblages at the marine‐freshwater transition. At lower elevations an intervening brackish phase suggests slower rates of uplift. Relative sea level rose to about +1 m about 9000 cal. yr BP to 8500 cal. yr BP, and then slowly fell to the modern datum. The mean rate of glacio‐isostatic rebound in the first millennium after deglaciation was about 0.11 in a ‐1, similar to the peak rate at the centres of the former Laurentide and Fennoscandian ice complexes. The latter feature smooth, exponential‐style declines in sea level up to the present day, whereas in the study area the uplift rate dropped to less than one‐tenth of its initial value in only about 2500 years. Slower, more deeply seated isostatic recovery generated residual uplift rates of <0.01 m a‐1 in the early Holocene after the late‐Pleistocene wasting of the Cordilleran ice sheet.
Dendrochronologically dated changes in the limit of pine in northernmost Finland during the past 7.5 millennia
Authors: HELAMA SAMULI , LINDHOLM MARKUS , TIMONEN MAURI , ERONEN MATTI
Published: July 2010

Postglacial changes in the occurrence of Scots pine in northernmost Finland and adjacent areas are indicated in data sets of megafossils dated to an accuracy of 1 year using analysis of tree rings. After adjustment for land uplift, results in the altitudinal and latitudinal extent and in the structure of the pine limit are compared in the context of megafossil and pollen evidence from Fennoscandia, the Kola Peninsula and Scotland. Temporal changes in tree density at the forest limit are estimated from chronology sample size. The record from the subregion of Enontekio shows a long‐term retreat of pine, corresponding to summer cooling caused by orbital forcing. This long‐term trend is superposed by shorter‐term fluctuations, which is consistent with other proxy evidence of pine. An abrupt decline in the forest limit occurred during the first millennium BC in two major steps, with no indication of high‐altitude pine germination between 800 BC and AD 100. The subregions of Inari and Utsjoki show significant fluctuations at the forest limit in tree density only.
Map and GIS database of glacial landforms and features related to the last British Ice Sheet
Authors: CLARK CHRIS D. , EVANS DAVID J. A. , KHATWA ANJANA , BRADWELL TOM , JORDAN COLM J. , MARSH STUART H. , MITCHELL WISHART A. , BATEMAN MARK D.
Published: July 2010

A review of the academic literature and British Geological Survey mapping is employed to produce a ‘Glacial Map’, and accompanying geographic information system (GIS) database, of features related to the last (Devensian) British Ice Sheet. The map (1:625000) is included in a folder and GIS data are freely available by web download (http:www.shef.ac.ukgeographystaffclark_chrisbritice.html). Emphasis is on information that constrains the last ice sheet. The following are included: moraines, eskers, drumlins, meltwater channels, tunnel valleys, trimlines, limit of key glacigenic deposits, glaciolacustrine deposits, ice‐dammed lakes, erratic dispersal patterns, shelf‐edge fans and the Loch Lomond Readvance limit of the main ice cap. The GIS contains over 20 000 features split into thematic layers (as above). Individual features are attributed such that they can be traced back to their published sources. Given that the published sources of information that underpin this work were derived by piecemeal effort over 150 years, then our main caveat is of data consistency and reliability. It is hoped that this compilation will stimulate greater scrutiny of published data, assist in palaeoglaciological reconstructions and facilitate use of field evidence in numerical ice‐sheet modelling. It may also help direct field workers in their future investigations.
Modern and Holocene hydrographic characteristics of the shallow Kara Sea shelf (Siberia) as reflected by stable isotopes of bivalves and benthic foraminifera
Authors: SIMSTICH JOHANNES , ERLENKEUSER HELMUT , HARMS INGO , SPIELHAGEN ROBERT F. , STANOVOY VLADIMIR
Published: July 2010

River discharge of Ob and Yenisei to the Kara Sea is highly variable on seasonal and interannual time scales. River water dominates the shallow bottom water near the river mouths, making it warmer and less saline but seasonally and interannually more changeable than bottom water on the deeper shelf. This hydrographic pattern shows up in measurements and modelling, and in stable isotope records (δ18 O, δ13 C) along the growth axis of bivalve shells and in multiple analyses of single benthic foraminiferal shells. Average isotope ratios increase, but sample‐internal variability decreases with water depth and distance from river mouths. However, isotope records of bivalves and foraminifera of a sediment core from a former submarine channel of Yenisei River reveal a different pattern. The retreat of the river mouth from this site due to early Holocene sea level rise led to increasing average isotope values up core, but not to the expected decrease of the in‐sample isotope variability. Southward advection of cold saline water along the palaeo‐river channel probably obscured the hydrographic variability during the early Holocene. Later, when sediment filled the channel, the hydrographic variability at the core location remained low, because the shallowing proceeded synchronously with the retreat of the river mouth.
Younger Dryas glacial advance in the southern Gulf of St. Lawrence, Canada: analogue for ice inception?
Authors: STEA RUDOLPH R. , MOTT ROBERT J.
Published: July 2010

In the summer of 1999, the Maritimes and Northeast Pipeline Company excavated a 3‐m‐deep trench across northern Nova Scotia exposing a continuous transect of surficial deposits along a 237‐km corridor. A Lateglacial palaeosol with preserved A horizon (peat and wood) buried under 2–10 m of surface till consisted mainly of herbaceous plant material with few large wood fragments. Large pieces of wood from two sites yielded conventional radiocarbon ages of 10.9 14C kyr BP (GSC‐6435) and 10.8 14C kyr BP (GSC‐6419). Previous to these finds, only a few localities were known to reveal till overlying peat, so the extent of Younger Dryas (YD) glaciers could not be clearly established. Glacial flow lines indicated by fabric and fluting of the YD surface till sheet in northern Nova Scotia and ice‐marginal deposits imply an ice cap centred over eastern P.E.I. and the southern Gulf of St. Lawrence. This glacier also dammed a series of glacial lakes against the highland‐rimmed west coast of Cape Breton Island. Glaciers developed and advanced during the YD in the uplands and offshore shelf areas from small remnants of Late Wisconsinan ice. Renewed ice growth was enabled by increased precipitation and local cooling in the Gulf of St. Lawrence due to deflection of the jet stream and expanded sea‐ice cover in the North Atlantic. The YD may provide an analogy to glacier development in Maritime Canada during the interglacial/glacial transition.
Terrestrial molluscan records of Weichselian Lower to Middle Pleniglacial climatic changes from the Nussloch loess series (Rhine Valley, Germany): the impact of local factors
Authors: MOINE OLIVIER , ROUSSEAU DENIS‐DIDIER , ANTOINE PIERRE
Published: July 2010

Two malacological sequences sampled in loess sections P1 and P3 of Nussloch (Rhine Valley, Germany) provide the most complete and precise molluscan record of western Europe for the Weichselian Lower and Middle Pleniglacial from about 70 to 34 cal. kyr BP. Qualitative and statistical analyses were performed on 134 mollusc samples. In the most complete Lower Pleniglacial record (P1), malacofauna changes reflect three short phases of vegetation development and climatic improvement related to soils and probably interstadials. A steppe to herb/shrub tundra shift characterizes the Lower‐Middle Pleniglacial transition and is followed in both malacological records by the same general environmental trend (decline in vegetation and humidity increase) ending with a new increase in temperature and vegetation cover at the top of P3. In the Middle Pleniglacial, the impact of each shorter climatic change on the malacofauna is less recognizable due to a higher sediment compaction and also to being differently recorded in both sequences as the local topography affects soil water resources, soil and vegetation development and malacofauna adaptation. A comparison shows that the western European biostratigraphical framework can thus be improved by coupling molluscan records from loess sections to pollen sequences.
Palynological data on major Holocene climatic events in NW Iberia
Authors: SOBRINO CASTOR MUÑOZ , RAMIL‐REGO PABLO , GÓMEZ‐ORELLANA LUIS , VARELA RAMÓN ALBERTO DÍAZ
Published: July 2010

Three NW Iberia Cantabrian Mountain pollen records are presented. They reflect the main Holocene climatic shifts in the North Atlantic region as recorded in the isotopic data from Greenland ice, Irish speleothems and reconstructed sea surface temperatures. Two brief forest regression episodes reconstructed from pollen may be synchronous with GH‐11.2 and GH‐8.2 events. At mid‐altitude, two woodland expansion phases (7000–6000 14C yr BP and 4000–2500 14C yr BP) are separated by a phase of heaths and peat deposits. Major woodland declines occurred during the Galician‐Roman Period (which includes the Bronze Age, the Iron Age and the Roman occupation) and from the end of the Medieval Period. The pollen data, backed up by archaeological and historical sources, suggest climatic impact of the Iron Age Cold Period, but are indecisive concerning the Little Ice Age. However, the pollen records do not support any significant ‘Neoglacial’ period (4000–3000 14C yr BP) influence on NW Iberia.
Hemoperfusion versus Hemodialysis in the Management of Patients Severely Poisoned by Organophosphorus Insecticides and Bipyridyl Herbicides
Authors: Okonek Stefan , Tönnis Hans Joachim , Baldamus Conrad August , Hofmannt Andreas
Published: July 2010

Organophosphorus insecticides (parathion, demeton‐S‐methyl sulfoxide, dimethoate) inhibit cholinesterase activity. Besides the well‐known resulting biochemical changes, there is evidence of direct toxic effects due to an excess of organophosphorus in blood and tissue. The therapeutic measure described here aims at eliminating organophosphorus.

Hemodialysis (HD) has no effect in parathion poisoning, but hemoperfusion with coated activated charcoal (HP‐CHAR) results in a clearance of 59.20% of the blood flow (ml/min) while the HP clearance with Amberlite XAD‐4 (HP‐XAD) is 81.33%. HD may be used in poisoning by demeton‐S‐methyl sulfoxide (clearance: 52.98%), and dimethoate (clearance: 59.07%), but HP‐CHAR clearance is much higher (83.70% and 87.84%, respectively). HP‐XAD clearance even reaches 100% of the blood flow.

Demeton‐S‐methyl sulfoxide and dimethoate are distributed almost equally in blood and tissue, and the effect of HP is indicated by a rapid decline in blood organophosphorus level as well as by an improvement in the signs and symptoms of the patient. Parathion accumulation is six to eight times higher in the tissue. This means there is protracted decline in blood level because of redistribution and less clinical evidence of improvement. However, animal trials demonstrate that HP‐CHAR results in a significantly faster decrease in parathion concentration in muscle and brain as compared with the control group. Hence, HP is an effective method for removing toxicologically relevant amounts of organophosphorus from the body.

Oral poisoning with bipyridyl herbicides such as paraquat (Gramoxone®) and diquat (Reglone®) is extremely serious. Fatal consequences occur after even one to three mouthfuls of the commercial liquid preparations. The literature reports that patients whose plasma levels within the first 48 hours exceed 0.1‐0.2 μg/ml have died, regardless of therapy. Recently, two patients with severe suicidal poisonings were treated by almost continuous HP (and HD) using 12 and 21 columns, respectively, for a period of two to three weeks. Paraquat plasma levels were 1.12 μg/ml and 1.44 μg/ml, respectively, within the first 48 hours after ingestion. Both patients survived without lung damage.

HP‐CHAR clearance (72.7 ml/min, blood flow 100 ml/min) clearly exceeds that of HD (11.5 ml/min, blood flow 100 ml/min) at these blood levels. Probably the affinity of coated activated charcoal for paraquat is superior to that of lung tissue. Hence, continuous HP‐CHAR is recommended in severe paraquat poisoning.
Comparison of a Steady Flow Pump to a Preload Responsive Pulsatile Pump in Left Atrial–to–Aorta Bypass in Canines
Authors: Runge Thomas M. , Grover Frederick L. , Cohen David J. , Bohls Frederick O. , Ottmers Stephen E. , Saadatmanesh Vahid
Published: July 2010

Abstract: A unique preload responsive pulsatile pump was compared to a centrifugal pump in total cardiac support in 25–kg canines (n = 6, each group) in the left atrialto–aorta mode during 5 h of ventricular fibrillation. With steady flow, there was immediate drop in output from 2.1 ± 1.0 L/min to 1.4 ± 0.3 L/min, followed by further reduction to 0.9 ± 0.2 L/min during 5 h of ventricular fibrillation. With a pulsatile pump, there was no significant reduction from control of 2.4 ± 0.6 L/min and no decline during 5 h of ventricular fibrillation. With steady flow, systemic vascular resistance (SVR) rose significantly from 1,762 dyne–s–cm‐5 immediately on pump to 3,013 dyne–s–cm‐ at 5 h. With physiologic pulsatile flow, significant elevation of SVR did not occur. When stressed, due to diminished left atrial return, the centrifugal pump displayed line chatter and streaks of microbubbles, whereas the pulsatile pump did not. Crystalloid volume replacement with the centrifugal pump was 6.5 ± 1.9 L, and with the preload responsive pulsatile pump, 5.6 ± 1.3 L. It is concluded that in the left atrial–to–aorta mode during 5 h of ventricular fibrillation and with comparable volume replacement, total cardiac support of canines is associated with lower SVR with physiologic pulsatile flow and is not accompanied by line chatter and cavitation with this preload responsive pump.
Theoretical Basis and Experimental Verification of the Impact of Ultrafiltration on Dialyzer Clearance
Authors: Waniewski Jacek , Werynski Andrzej , Ahrenholz Peter , Lucjanek Piotr , Judycki Wladyslaw , Esther Gisela
Published: July 2010

Abstract: Dialyzer clearance K is usually presented as K=KO+ Tr Qu, where Qu is ultrafiltration rate, K0 is clearance for Qu– 0, and Tr is transmittance coefficient. Although a simple and accurate mathematical description of Ko is widely used, only a somewhat inaccurate formula for Tr that predicts a linear relationship between Tr and Ko has been proposed before. In this study the detailed investigation of Tr using a one–dimensional theory of a dialyzer is presented. In general, the application of a one–dimensional theory requires sophisticated numerical methods, but for small and middle molecular weight solutes an analytical formula for K can be derived. Tr predicted by the developed theory in comparison to Tr predicted by the previous linear formula is higher for small molecular weight solutes and lower for middle and large molecular weight solutes. These theoretical results were confirmed in experiments carried out in vitro for hollow–fiber dialyzers and small molecular weight solutes (urea, creatinine, sodium, TcO4) as well as middle molecular weight solutes (vitamin B12).
Development of a New Moving–Actuator Type Electromechanical Total Artificial Heart
Authors: Min Byoung G. , Kim Hee C , Lee Sang H. , Kim In Y. , Kim Jong W. , Choi Jin W. , Kim Jin T. , Jung Dae Y.
Published: July 2010

Abstract: A new type of electromechanical total artificial heart based on a moving–actuator mechanism was developed to decrease the total pump size and to improve the fitting characteristic of the pump to atrial remnants and arterial vessels. The blood pump consists of three major parts: right and left blood sacs and a moving pump actuator between two sacs. The total weight is 810 g and the volume of the pump is 770 ml. The actuator rolls back and forth on a circular track, producing alternating blood ejection. The pump performance was evaluated in mock circulation and animal implant experiments. The pump was implanted for 100 h in a calf (˜100 kg) with a stable he modynamic state until accidental (electrical short circuit) death.
Electrohydraulic‐Clamshell Heart with Energy Converter Inside the Compliance Reservoir
Authors: Kolff W.J. , Topaz Stephen , Bishop Dan , Smulders Yvo , Golub Dmitry , Yuan Bi , Topaz Peter , Dietz Wolfgang , Stegeman Mark , Scholten Eduard , van der Werve Michael , Jaarsma Ruurd , Mohammad Fazal , Kinoshita Masayuki , Chiang Bang Yu
Published: July 2010

Abstract: Two new ideas on the electrohydraulic actuation of blood pumps have been combined. The first idea was to put the energy converters that propel the hydraulic fluid inside the compliance reservoir instead of having them separate. Compactness of the device and better cooling of the energy converter by the surrounding fluid are two major advanages of this approach. Secondly, we put the pumping membrane inside a clamshell that fits over a soft ventricle (I). The ventricle can be implanted first, after which the shell is slid over it. These two ideas have resulted in devices described in this paper. Preliminary in vitro and in vivo data are presented.
Devices for the Treatment of Diabetes: Today
Authors: Scheen Andre J.
Published: July 2010

Abstract: Although single or multiple daily subcutaneous injections of insulin with syringes are the mainstay of insulin delivery techniques for the treatment of diabetes mellitus, several other methods are now available. The present paper will review the main problems occurring with the classical subcutaneous insulin therapy and the possible solutions given by the use of new devices, including more particularly insulin jet injectors, pens, and portable pumps. This review has to be considered as an introduction to the presentations of this symposium devoted to implantable pumps, glucose sensors, and artificial pancreas, respectively.
On‐Line Cell Manipulation for Cancer Treatment
Authors: Tani Tohru , Numa Kenji , Abe Hajime , Yokota Tohru , Kodama Masashi
Published: July 2010

Abstract: We hypothesized that the host immune system is directly stimulated by contact between blood and the materials used in blood purification systems. This concept has never been applied in therapeutic plasmapheresis. Two new materials have been invented since 1983. One of those is lipopolysaccharide (LPS)‐immobilized beads, which are chemically bonded bacterial LPS (LPS‐B). Another is immobilized pokeweed mitogen (PWM‐B). We studied these two materials for their anti‐tumor cell activity in vitro and in vivo. Their efficacy on tumor cells was demonstrated to be much stronger than that of lymphocyte activated killer (LAK) cells. Our new concept was proven to be correct.
In vivo Patency of Endothelial Cell‐Lined Expanded Polytetrafluoroethylene Prostheses in an Ovine Model
Authors: James Natalie L. , Schindhelm Klaus , Slowiaczek Peter , Milthorpe Bruce , Graham Anthony R. , Munro Vince F. , Johnson Graham , Steele John G.
Published: July 2010

Abstract: The performance of small‐diameter vascular prostheses may be improved by implantation of grafts lined with endothelial cells. Expanded polytetrafluoroethylene (ePTFE) prostheses (4 mm × 40 mm) were coated with fibronectin (20 γg/ml), seeded with endothelial cells, and cultured for 48 h to produce a confluent, autologous endothelial cell lining. They were implanted as carotid interposition grafts in sheep. Seeded ePTFE grafts were compared with nonseeded ePTFE grafts and autologous carotid artery grafts. No anticoagulant or antiplatelet therapy was administered. making this a stringent test model for the thromboresistance of a small‐diameter prosthesis. After 13 weeks the patencies of seeded, nonseeded, and autologous artery grafts were 16% (116), 0% (0/6), and 100% (6/6), respectively. The one seeded graft that was patent was fully lined with endothelial cells and showed no stenosis. The remaining five seeded grafts were occluded by fibrous tissue and displayed substantial spindle cell hyperplasia. There was no apparent difference between the autologous artery grafts and normal arterial tissue, and the anastomoses showed no stenosis. The ovine model provides a conservative test of prosthesis survival and may be useful for study of graft failure.