bluuebunny/crossref_metadata_2025_split huggingface dataset:
Late devensian ice sheet in the western Grampians, Scotland
Authors: Thorp Peter W. 
Published: February 2007

AbstractA radial pattern of ice flow of the last ice sheet in the largest source area of ice (c. 5000 km2) in the British Isles in western Scotland is demonstrated by the dispersal of indicator erratics and by patterns of striae, friction cracks and ice‐moulded landforms. Three major ice domes and the principal ice divide are identified in the western Grampians. The ice domes coincided with the highest mountain blocks while it is inferred that the alignment of many of the pre‐existing valleys controlled much of the outflow of ice, forming ice streams within the ice sheet. The importance of the Rannoch Moor basin as a radial provider of ice to surrounding areas was apparently less significant than has hitherto been considered. Ice flowed into and across the southern part of the basin from the principal ice divide located to the west and south. No evidence has yet been found that would support a model of an eastward‐migrating ice divide either during the build‐up or during the deglaciation of the Late Devensian ice sheet.
Palaeoecological investigations towards the reconstruction of the post‐glacial environment at Lough Doo, County Mayo, Ireland
Authors: O'connell Michael , Mitchell Frazer J. G. , Readman Peter W. , Doherty Terence J. , Murray Declan A. 
Published: February 2007

AbstractResults of palaeoecological studies involving pollen analytical, chemical and palaeomagnetic investigations on a 3 m core from Lough Doo, NE County Mayo, are presented. The record, which commences shortly after 7000 BP, shows a sharp Alnus expansion coinciding with a decline in Pius at 6400 BP, an elm decline taking place in the context of severe soil erosion and the final decline of Pinus occurring as the chemical record indicates onset of severe reducing conditions in the catchment. Pine becomes extinct at or shortly before 3200 BP in the context of increased farming activity and the expansion of blanket bog in the adjacent upland areas. A later feature (c. 1880 BP) is the expansion of Taxus to 7.1% of total pollen.On the basis of the palynological evidence, it is concluded that there were no major Neolithic Landnam phases, which contrasts sharply with the evidence for widespread woodland clearance and the laying out of extensive and regular field systems in the northern coastal part of County Mayo. In the upper part of the core a severe inversion of 14C dates is recorded. On the basis of the palaeomagnetic and pollen evidence this began at c. 1500 BP and is considered to have been initiated in the context of woodland clearance and a renewal in farming activity.
Ice‐wedge casts and relict polygonal patterns in Scandinavia
Authors: Svensson Harald 
Published: February 2007

AbstractIce‐wedge casts in Scandinavia frequently occur in three regions: (a) southwestern Jutland (outside the limit of the Weichselian glaciation); (b) southwestern Sweden; and (c) northernmost Norway. The latter two areas are both early deglaciated regions. Characteristics of casts in vertical sections are discussed with reference to the host and infilling material. Aerial photographs provide an effective tool for detecting relict ice‐wedge polygons (crop marks, micromorphology). Experience from present‐day permafrost regions with active ice‐wedge formation helps to explain the palaeoclimatic significance of the relict polygons. Attempts to establish the ages of formation are discussed from a methodological point of view.
The significance of cryoturbation phenomena in environmental reconstruction
Authors: Van Vliet‐Lanoë Brigitte 
Published: February 2007

AbstractCryoturbation results mainly from differential heave related to (1) drainage and thermal conditions and (2) frost susceptibility. Loadcasting and cryostatic pressures are restricted to wet soils such as pure silt or silty sand. The translocation of fine particles resulting from repeated freezing and thawing can promote frost susceptibility in a previously non‐susceptible material, as well as a loss in stability of the surface horizons (liquefaction). Small and metric scale cryoturbations can be explained by this process. Large scale deformations and injections may be related to abnormal liquefaction not necessarily associated with frost. Regular patterns are associated with fissure nets. Upturned injections in a downslope direction attest to cryoturbation and frost creep. A lowering of the water table promotes the formation of drop‐like cryoturbations, most of which can be related to seasonal frost in imperfectly to poorly drained soils. They are not indicative of permafrost except in well drained situations or in the case of flat bottomed involutions.
An Ipswichian fluvial deposit at Fulbeck, Lincolnshire and the chronology of the Trent terraces
Authors: Brandon Allan , Sumbler Michael G. 
Published: February 2007

AbstractMammalian fossils recently discovered near Fulbeck in Lincolnshire, include abundant hippopotamus, suggesting an Ipswichian date for the Fulbeck Sand and Gravel (new name). These deposits mark a former course of the River Witham; clasts indicate derivation from outcrops of Jurassic rocks and chalky till to the south and south‐east. The relationship of the Fulbeck Sand and Gravel to the terrace deposits of the River Trent necessitates a revised chronology. The Balderton Sand and Gravel (new name), laid down by the Trent along its former course to the Lincoln Gap, is shown to be older than the Ipswichian Fulbeck Sand and Gravel, and was probably deposited during the Wolstonian Stage. The Eagle Moor Sand and Gravel (new name), probably glaciofluvial outwash from the chalky tills of the region, is considerably older than the Balderton Sand and Gravel and, together with the tills, is assigned to the early part of the Wolstonian, or the Anglian glacial Stage. It is suggested that the Balderton and Eagle Moor terraces equate with the lower and upper facets of the composite Hilton Terrace of the Middle Trent.
Variations in the pattern and rate of isostatic uplift indicated by a comparison of Holocene sea‐level curves from Scotland
Authors: Haggart B. Andrew 
Published: February 2007

AbstractDifferences in the timing of maxima and minima and shape between sea‐level curves from the western Forth valley, lower Strathearn, inner Moray Firth and eastern Solway Firth areas of Scotland are interpreted as being due to differences in isostatic uplift and different methodologies used to interpret the basic data. Possible changes in the relative rates of uplift between areas suggest that the practice of applying the western Forth ‘model’ of relative sea‐level change to other parts of Scotland must be questioned.
Reconstructing past glacier dynamics and erosion from glacial geomorphic evidence: Snowdon, North Wales
Authors: Sharp Martin , Dowdeswell Julian A. , Gemmell J. Campbell 
Published: February 2007

AbstractBedrock surfaces exposed around Llyn Llydaw, North Wales demonstrate contrasting styles of erosion beneath a Late Devensian ice sheet and a Loch Lomond Stadial (LLS) valley glacier. Ice sheet erosion involved lee‐side fracturing, surface fracture wear and abrasive wear, while LLS erosion was primarily by abrasive wear. Preservation of ice sheet erosional features indicates limited rates of erosion during the LLS. Analysis of the geometry and distribution of erosional markings suggests that the low erosional capacity of the LLS glacier was due to a low basal sliding velocity. This prevented the formation of lee‐side cavities, reduced the debris flux over the bed and minimised particle‐bed contact loads. Reconstructions of the mass balance and geometry of the LLS glacier indicate that most of its balance velocity could be achieved by internal deformation alone. A combination of low subglacial water pressures and an unusually rough substrate explain the low sliding velocities. High bed roughness is due to the absence of leeside cavities and a change in flow orientation between ice sheet and LLS times, which meant that the LLS glacier was in contact with roughness elements which were generated in cavities beneath the ice sheet.
Loess—palaeosol sequence in Kashmir: Correlation of mineral magnetic stratigraphy with the marine palaeoclimatic record
Authors: Gupta S. K. , Sharma P. , Juyal N. , Agrawal D. P. 
Published: February 2007

AbstractIn this paper we use the mineral magnetic data (χ and χfd) to stratigraphically correlate different loess‐palaeosol profiles in Kashmir Valley. The two available thermoluminescence (TL) chronologies on the Kashmir loess profiles have been reinterpreted to identify the soil of the Last Interglacial (ca. 125 000 yr BP). We show that the mineral magnetic data correlates well with the global marine δ18O record. This correlation has revealed the well‐known Milankovich periodicities of 40 ka and 20 ka in the loess‐palaeosol record. On the basis of this study, we conclude that loess deposition in the Kashmir Valley started around 200 ka and not 350 ka ago as suggested by earlier workers, and that magnetic susceptibility variations provide a tool to decipher climatic changes from loess‐palaeosol sequences.
Morphology and stratigraphy from several deglaciations in the Transtrand Mountains, western Sweden
Authors: Kleman Johan , BorgströM Ingmar , Robertsson Ann‐Marie , Lilliesköld Marianne 
Published: February 2007

AbstractThe Transtrand Mountains, western Sweden, are characterised by an abundance of glaciofluvial meltwater channels. Crossing lateral channels and channel systems overprinted by fluting occur at several localities. Drainage channel systems from three older deglaciations are interpreted to have been preserved despite overriding by later ice sheets. Deep sections, machine excavated into the summit surface of the Hundfjället Mountain, revealed the presence of two lower diamictons into which two older generations of lateral channels were cut, and subsequently buried by a Late Weichselian basal till. Buried frost‐sorted structures, and frost‐fractured bedrock below the lowermost till, indicate the repeated occurrence of periglacial condil conditions. An organic layer between the two older units yielded an infinite radiocarbon age of > 45000 yr BP. The pollen content of this layer indicates a local mountain heath flora dominated by ericaceous dwarf shrubs and graminids. The climate phase is interstadial or the beginning or end of an interglacial. The different diamictons also display different pollen spectra. During the last deglaciation the ice flow was from the north‐northeast. The second youngest system of drainage channels corresponds to ice flow from approximately west‐northwest. There are still older traces of separate deglaciation events from the east and north. A frozen bed is interpreted to have been the standard basal regime for the last ice sheets to cover the Transtrand Mountains.
Allt Odhar and Dalcharn: Two pre‐Late Devensian/Late Weichselian sites in northern Scotland
Authors: Walker M. J. C. , Merritt J. W. , Auton C. A. , Coope C. R. , Field M. H. , Heijnis H. , Taylor B. J. 
Published: February 2007

AbstractThe lithostratigraphy and biostratigraphy of two sites (Allt Odhar and Dalcharn) in north‐central Scotland are described, where pollen spectra of temperate affinity have been obtained from organic deposits that underlie till. The pollen record from Allt Odhar, in association with evidence from plant macrofossils and Coleoptera, shows the expansion of birch woodland and its eventual replacement by open grassland under a climatic regime slightly cooler than that prevailing in the northern highlands of Scotland at the present day. The organic sediments accumulated during an Early Devensian interstadial episode, which has been dated by the uranium series disequilibrium method to ca. 106 ka BP. Evidence for one and possibly two Devensian glaciations may be preserved at the site. The pollen record from Dalcharn, by contrast, reflects the middle and later stages of an interglacial cycle with the transition from pine forest to grassland. The overlying till sequence contains evidence of at least two separate glacial episodes. The age of the warm stage cannot be established precisely on present evidence, but there are indications that it may predate the last (Ipswichian) interglacial. These are the first sites from the mainland of Scotland to provide evidence of wooded conditions during interstadial and interglacial episodes of the Middle/Late Pleistocene.
Late Devensian and Flandrian palaeoenvironmental changes on the Scottish continental shelf west of the Outer Hebrides
Authors: Peacock J. D. , Austin W. E. N. , Selby I. , Graham D. K. , Harland R. , Wilkinson I. P. 
Published: February 2007

AbstractExamination of two radiocarbon‐dated vibrocores taken from south of St Kilda at a water depth of about 155 m, a short distance within the maximum position of the Late Devensian (Dimlington Stadial) ice sheet, suggests that the St Kilda Basin became free of glacier ice after 15250 yr BP. Sedimentation in a shallow, low energy, high arctic, muddy environment continued until after 13500 yr BP. There followed a higher energy temperate episode during which water depths were roughly about 40 m: this is correlated with the latter part of the Windermere Interstadial and with the warmer interval known in shallow Scottish seas about or a little before 11 000 yr BP. The Loch Lomond (Younger Dryas) Stadial is marked in the vibrocores by the return of muddy sediments and a cold‐water fauna. Relatively shallow water conditions seem to have persisted into the earliest Flandrian, when the water depth was still roughly 60 m, corresponding to a sea‐level in the area 90–100 m below present. It is suggested that pack ice was widespread in the northeast Atlantic before the Windermere Interstadial and also during the Loch Lomond Stadial, when it transported shards of Icelandic volcanic ash into the St Kilda basin. Estimates of sea‐surface temperature for the last part of the Windermere Interstadial are close to those derived from the deep‐sea record for the same period.
Late‐glacial climatic oscillations as recorded in Swiss lake sediments
Authors: Eawag A. F. Lotter , Eicher U. , Siegenthaler U. , Birks H. J. B. 
Published: February 2007

AbstractRegional pollen assemblage zones for the late‐glacial period of the Swiss Plateau are introduced and defined. They include four major zones (Artemisia, Juniperus—Hippophaë, Betula, Pinus PAZ) with several subzones. Pollen and oxygen‐isotope analyses on lacustrine sediments from several lakes in the area reveal four distinct phases of climatic oscillation in the time period of 13 000‐9500 yr BP.The first oscillation, termed the Aegelsee fluctuation, occurs shortly before 12 000 yr BP and varve counts suggest its duration was ca. 100 yr. It is characterised by a short decrease in the oxygen isotopes as well as a short increase in NAP associated with a depression in birch pollen values. The second oscillation, which occurs in the δ18O record shortly before the deposition of the Laacher See Tephra (ca. 11 000 yr BP), is termed the Gerzensee fluctuation. It occurs during a pine‐dominated phase and its vegetational effects cannot be determined palynologically. The most prominent regressive phase is the Younger Dryas biozone (ca. 10 700‐10 000 yr BP) characterised by an increase in heliophilous NAP and low δ18O values. The Younger Dryas biozone can often be subdivided palynologically into two parts: a first part rich in grasses and juniper and a second part with higher Filipendula and birch values. During the Preboreal biozone another distinct oscillation is evidenced only in the oxygen isotope ratios.Comparison of the Swiss oxygen isotope profiles with the Greenland Dye 3 record suggests that not only the three major shifts in the δ18O curves but also the minor ones are closely comparable, suggesting some common climatic control.
Pleistocene stratigraphy in the Devils Hole Area, Central North Sea: Foraminiferal and amino‐acid evidence
Authors: Knudsen Karen Luise , Sejrup Hans Petter 
Published: February 2007

AbstractA detailed study of the foraminiferal assemblages from the 229.1‐m‐deep core 81/34 in the central North Sea has been combined with a series of measurements of the isoleucine epimerisation of foraminiferal tests. A total of 17 foraminiferal zones have been established and both the faunal compositions and the amino‐acid values suggest that a major part of the sequence represents deposits of early and middle Pleistocene age. Only the uppermost zone is referred to the late Pleistocene.The sequence mainly comprises a series of marine zones from cold periods, but with some barren, possibly non‐marine intervals in between. Only two of the foraminiferal zones can be referred to interglacial periods. The oldest one of these, defined here as the Devils Hole Interglacial, may belong to the latter part of the Cromerian Complex, while the upper warm interval is correlated with the Holsteinian of northwest Europe on the basis of its amino‐acid values.A detailed stratigraphical correlation between core 81/34 and the neighbouring core 81/29 is suggested on the basis of their foraminiferal content, palaeomagnetic evidence and amino‐acid measurements from both cores. A characteristic feature of both sequences is that most of the Quaternary record is missing. Similar episodic patterns of deposition and erosion have been reported previously from the North Sea area.
Palaeoecology of a late Allerød peat bed at Godøy, western Norway
Authors: Birks Hilary H. , Lemdahl Geoffrey , Svendsen John Inge , Landvik Jon Y. 
Published: February 2007

AbstractA peat bed found under solifluction deposits on Godøya island, western Norway, accumulated during a few decades around 11 000 yr BP, at the end of the Allerød period of the Late Weichselian. Palaeoecological investigations showed a local vegetation succession on wet sand culminating in a mire community dominated byCarex nigra. Periodic flooding brought in sand and silt, which decreased as drainage was impeded sufficiently for standing water to develop. The surrounding terrestrial vegetation was dominated bySalixscrub, with some open heath and alpine habitats nearby. Apart from two aquatic species, the 29 insect taxa recorded are characteristic of alpine heaths, plant litter (underSalixscrub) and stream‐sides. Their remains, together with the terrestrial plant macrofossils, were washed into the mire from nearby.Because the fossils are locally derived, the environmental reconstructions are of the actual conditions at Godøy at ca. 11 000 yr BP. Palaeotemperature estimates from beetles and plants are in agreement. The coleopteran estimates (Mutual Climatic Range Method) suggest mean July temperatures of 10–13°C, slightly cooler than today (13.5°), and January temperatures between +1 and −10°C, similar to or much colder than today. Summer temperature estimates from individual plant taxa indicate that temperatures during the Allerød period were similar to today's, but estimates from the reconstructed vegetation and timber‐line positions give estimates up to 3.5° cooler. Temperatures fell 2.5–7.5°C at the Younger Dryas. This abrupt and severe cooling initiated the solifluction processes on Godøya that buried the peat.The Godøy peat bed and its contained fossils provide a rare glimpse of Allerød biota and environments at the local (site) scale.
Stratigraphy and palaeoecology of a possible interglacial site, northernmost Ellesmere Island, Canada
Authors: Evans D. J. A. , Mott R. J. 
Published: February 2007

AbstractAn extensive stratigraphic section at Cape Alfred Ernest on the Wootton Peninsula, northwest Ellesmere Island contains six lithofacies which appear to record two glacial phases separated by an organic layer. (1) A lower massive gravel records a pre‐ice advance outwash phase; (2) massive fine‐grained sediments record a period of non‐glacial marine deposition when sea‐level was higher than present; (3) a massive diamicton records the advance of ice across the site; (4) intermediate stratified beds record supraglacial and proglacial outwash, and include an organic layer; (5) massive diamicton grading down‐valley to stratified diamicton and then massive, sheared diamicton, overlain by laminated fine‐grained sediments with dropstones, recording the last (late Wisconsinan) glaciation; (6) upward‐coarsening sands and gravels record proglacial outwash and grade to raised marine deltas.Radiocarbon dates of 39270 ± 640 and > 51000 yr BP were obtained on samples from the organic layer by accelerator mass spectrometry and conventional radiocarbon dating, respectively. Palaeoecological data suggest that the organics accumulated in a wet sedge meadow environment when the climate was warmer than present. Stratigraphic considerations suggest that the organic layer represents an interglacial interval which, if valid, indicates that the site constitutes the northernmost interglacial stratigraphy in the Canadian Arctic. Alternatively, the organic layer may date to Plio‐Pleistocene times.
The middle pleistocene deposits of Waverley Wood Pit, Warwickshire, England
Authors: Shotton F. W. , Keen D. H. , Coope G. R. , Currant A. P. , Gibbard P. L. , Aalto M. , Peglar S. M. , Robinson J. E. 
Published: February 2007

AbstractA complex of channels underlying the Baginton‐Lillington Gravel (Baginton Formation) at Waverley Wood Quarry, Warwickshire is described. Fossil pollen and plant macrofossils, Coleoptera, Ostracoda, Mollusca and Mammalia are described from the channel‐fill deposits. Consideration of all the evidence allows the identification of four separate stages of channel fill which largely occurred under a cool temperate climate. At the top of Channel 2 evidence for a cold, continental climatic episode can be recognised, suggesting that the whole complex was deposited under a fluctuating climate at the end of a temperate stage. At two levels in the channels human artefacts were recovered confirming the presence of Palaeolithic people in Warwickshire during the deposition of the sediments. Amino‐acid geochronology suggests an age within the ‘Cromerian Complex’ Stage for the channels. The small vertebrate and molluscan faunas indicate that the deposits are no older than the latter part of the ‘Cromerian Complex’ Stage of East Anglia. The regional stratigraphic significance of the Waverley Wood succession is outlined.
Fissure‐fill and tunnel‐fill sediments: expressions of permafrost and increased hydrostatic pressure
Authors: Kumpulainen Risto A. 
Published: February 2007

AbstractA spectacular network of fissure fillings and pipes (tunnels) cuts Quaternary gravelly delta deposits northeast of Myvatn, precisely on the spreading axis of the North Icelandic rift zone. The delta was formed in an ice‐contact lake during deglaciation towards the end of the last glaciation. Subsequently the lake was drained and permafrost conditions developed in these poorly sorted gravel deposits. Hydrostatic pressure was transmitted from the adjacent glacier to the non‐frozen core of the delta beneath the discontinuous permafrost crust and the seasonally frozen active layer. Owing to increased hydrostatic pressure, a network of subhorizontal to vertical fissures was opened along the taliks. In these fissures free ground‐water flow and sediment transport were established. Tunnel erosion and probably also seepage erosion were associated with these fissures. Subsequently, the fissures and tunnels were filled by laminated fine sediments interbedded with poorly sorted material resulting in the formation of fissure‐fill sediments and tunnel‐fill sediments.