bluuebunny/crossref_metadata_2025_split huggingface dataset:
A regional high‐frequency reconstruction of May–June precipitation in the north Aegean from oak tree rings, A.D. 1089–1989
Authors: Griggs Carol , DeGaetano Arthur , Kuniholm Peter , Newton Maryanne 
Published: February 2007

AbstractMay–June precipitation is the primary limiting factor in annual tree‐ring growth of the oaks of northeastern Greece and northwestern Turkey (39–42°N, 22–37°E). In a regional tree‐ring chronology of historic building and modern forest samples, the May–June precipitation explains at least 40% of the variance for 1900–1985, and is reconstructed here from A.D. 1089–1989. The reconstruction is compared to three other precipitation reconstructions for Turkey. The mean temperature of May and June is also a growth‐limiting factor owing to its effect on the availability of precipitation to the trees, but is more difficult to calibrate and reconstruct accurately owing to the trees' indirect response and the low number of long‐temperature records available for the interior of northwestern Turkey.An analysis of the various methods of manipulating oak tree‐ring data for regional climate reconstruction shows that removing all but the high‐frequency variability plus normalizing the oak data sets before combining them into a master chronology are optimal techniques for a reasonable precipitation reconstruction of the entire area over the instrumental period. However, these methods do remove the low‐frequency signal and dampen some of the evidence of local extremes in May–June precipitation; these issues are discussed here and will be addressed in future research. Copyright © 2007 Royal Meteorological Society
Freshwater organic deposits and stratified sediments between Early and Late Midlandian (Devensian) till sheets, at Aghnadarragh, County Antrim, Northern Ireland
Authors: McCabe A. Marshall , Coope G. Russell , Gennard Dorothy E. , Doughty Philip 
Published: February 2007

AbstractThe following events have been identified from a complex sequence of Midlandian (Devensian) sediments recently exposed at Aghnadarragh, County Antrim: (1) A lower till interpreted as Early Midlandian was deposited by a major lowland ice sheet which moved south‐eastwards from central Ulster across the Lough Neagh depression. (2) Deglacial conditions were followed by a periglacial phase characterised by ice‐wedge growth and sedimentation by gravelly debris flows. The latter contain the oldest known remains of Mammuthus primigenius in Ireland. (3) An Early Midlandian interstadial is represented by a woody detritus peat, with evidence of Betula, Pinuos and Picea woodlands and a rich beetle fauna. Wood from this horizon has been shown to be beyond the range of radiocarbon dating (>48 180 BP). (4) Interstadial conditions were succeeded by a cold, non‐glacial phase dominated by in‐channel gravelly flows and deposition of organic muds which contain plant and insect fossils. These horizons are older than 46 850 BP. (5) An upper, non‐drumlinised till was deposited during the Late‐Midlandian by a major lowland ice sheet which moved generally eastwards across the Lough Neagh Lowlands from central Ulster. This glaciation probably reached its maximum at ca 20–24 ka. (6) Drumlin formation occurred in the Lough Neagh Lowlands towards the end of the Late‐Midlandian. The limiting moraines are dated to 17 ka. The lower till at Aghnadarragh is the first positive record of a major lowland ice sheet in Ireland during the early part of the last cold stage. The Early Midlandian interstadial peats have not been documented elsewhere in Ireland and correlate broadly with the Chelford Interstadial complex of the English Midlands. Related exposures elsewhere in Ulster confirm that the middle part of the last cold stage was free of major lowland ice masses but deposits of this period are absent from Aghnadarragh.
Arctic‐alpine brown soils as a source of palaeoenvironmental information: Further 14C dating and palynological evidence from Vestre Memurubreen, Jotunheimen, Norway
Authors: Matthews John A. , Caseldine Christopher J. 
Published: February 2007

Abstract14C dating and pollen analytical evidence is presented relating to the usefulness of arctic‐alpine Brown Soils for palaeoenvironmental reconstruction. A present‐day soil has been examined together with its continuation beneath the outermost ‚Little Ice Age’︁ end moraine of the glacier Vestre Memurubreen at a location well above the tree‐line in the mid‐alpine belt of southern Norway. Fourteen 14C dates from chemically‐fractionated soil samples, which range in age from 495 ± 55 14C yr in the uppermost 1 cm to > 4000 14C yr within 13 cm of the buried soil surface, demonstrate near‐linear age/depth gradients in the palaeosol. Continuous development of the palaeosol over at least 5000 calendar yr prior to burial confirms that Vestre Memurubreen attained its Neoglacial maximum extent in the ‚Little Ice Age’︁. Pollen stratification in buried and unburied profiles indicates a single vegetation change from a low‐alpine dwarf‐shrub heath to a mid‐alpine ‚grass’︁ heath, reflecting an altitudinal lowering of vegetation belts and a possible climatic cooling of 2‐4°C. Surface additions of allochthonous (aeolian) mineral particles appear to have contributed to soil development, whilst mixing processes have been relatively unimportant at this site. The immobilisation of resistant organic residues and the ineffectiveness of biological and chemical activity are major reasons for the preservation of a palaeoenvironmental record in these high altitude soils.
The use of mineral magnetic analyses in the study of glacial diamicts: A pilot study
Authors: Walden John , Smith John P. , Dackombe Roger V. 
Published: February 2007

AbstractMineral magnetic methods of characterising glacial diamicts and their associated sediments are applied to deposits within the Manx Quaternary sequence. The possible advantages of these techniques over more traditional methods of sediment characterisation are outlined, and the results obtained in a pilot study are examined. Results show that both distinctions and similarities exist within the magnetic mineral assemblages of the four diamict units studied. The possible implications of these results for interpreting the Late Quaternary history of the Isle of Man and the future potential of the techniques are briefly discussed.
Lower Pleistocene deltaic and marine sediments in boreholes from the central North Sea
Authors: Stoker Martyn S. , Bent Alistair J. A. 
Published: February 2007

AbstractLower Pleistocene sediments recovered in boreholes from the Aberdeen Ground Formation in the central North Sea indicate that the unit was deposited in a delta front to prodelta/shallow, open shelf marine setting. Possible estuarine and clastic nearshore marine deposits have been identified on the western margin of the basin. The delta front sediments consist of interbedded, structureless to laminated sands and muds with organic debris, ferruginous nodules and common soft sediment deformation structures. Sporadic rippled and graded beds, basal scours to beds and starved ripples suggest periodic wave–current reworking. Prodelta/shelf marine sediments are predominantly argillaceous with only occasional thin sand beds and rare phosphatic bands. One exceptionally thick sand body or submarine channel‐fill although this remains uncertain. The estuarine/clastic nearshore marine sediments include coarse channel‐lag deposits and rippled and laminated subtidal sands. A rich microfossil assemblage recovered from the prodelta/shelf marine sequence indicates that deposition occurred under fluctuating climatic conditions.
The ‚loess’︁ section at Borden, Kent, SE England
Authors: Catt John A. , Bateman Richard M. , Wintle Ann G. , Murphy Christopher P. 
Published: February 2007

AbstractA 5.3m profile originally described as loess with a buried interglacial soil is reinterpreted from petrographic evidence and thermoluminescence dating as a Holocene colluvial accretionary soil. Mineralogical analyses of coarse silt (16–63 μm) fractions suggest that most of the silty colluvium was derived from weathered Thanet Beds upslope, though some loess was incorporated during the final depositional phase. Thin sections show that clay illuviation occurred penecontem‐poraneously with deposition of colluvium. Thermoluminescence properties suggest partial optical bleaching of the grains during rapid deposition, which is consistent with a Holocene colluvial origin.
Introduction
Authors: French Hugh M. , Koster Eduard A. 
Published: February 2007

AbstractEnvironmental reconstructions utilising the evidence of relic or fossil periglacial features are necessarily based on the nature and present distribution of comparable active features. The most critical features are those indicative of permafrost, because of the negative mean annual temperatures required for permafrost, whereas many other cold climate features are much less informative as to temperature implications. (Washburn, Geocryology, 1980, 279).
The permafrost regime in the Mackenzie Delta, Beaufort Sea region, N.W.T. and its significance to the reconstruction of the palaeoclimatic history
Authors: Allen Diana M. , Michel Frederick A. , Judge Alan S. 
Published: February 2007

AbstractObserved depths to the base of the ice‐bearing permafrost (!BPF) as determined from geophysical well‐log and survey information in the Mackenzie Delta and offshore Beaufort Sea continental shelf show significant variation. Depths range from over 700m beneath the northeastern portion of Richards Island and the adjacent offshore region to the north, to less than 100m in the modern Mackenzie Delta and offshore Mackenzie Bay regions. Along the Tuktoyaktuk Peninsula, permafrost thicknesses exceed 600m but tend to thin to less than 100m in a southeasterly direction.The wide variation in the thickness and distribution of permafrost is due in part to differences in the subsurface deltaic lithologies and to the complexity of the past surface temperature history, exhibited, for example, by fluctuations of the mean annual ground temperature. Geological cross‐sections showing variation in the Tertiary and Upper Cretaceous deltaic sequences indicate a good correlation with the permafrost distribution. In particular, where the sand and gravel units of the Iperk and Kugmallit Sequences predominate, permafrost is thick owing to the high thermal conductivities of the ice‐rich sediments. Conversely, where the low thermal conductivity shales and mudstones of the Richards Sequence are present, permafrost is accordingly thinner.Numerical models of permafrost aggradation in the Mackenzie Delta region suggest that Early and Late Wisconsinan surface temperatures were of the order −18°C. A mid‐Wisconsinan rise in temperature to approximately −8°C, similar to mean surface temperature today, is also indicated. This proposed palaeoclimate is sufficient to account for the observed maximum permafrost thicknesses in the region.
A constraint to the Wisconsinan glacial history, Canadian Arctic Archipelago
Authors: Taylor Alan 
Published: February 2007

AbstractThick ice‐bearing permafrost is not observed today beneath the deeper channels of the central Queen Elizabeth Islands, Canadian Arctic Archipelago. Analysis of a precision temperature log recently obtained at an offshore well near Ellef Ringnes Island indicates that the thermal regime beneath the seabed is in equilibrium with today's marine environment. If thick permafrost similar to that observed on land today had existed in the Pleistocene in areas that are presently offshore, then such permafrost must have started melting no later than 25000 years ago in order to allow the present thermal regime to evolve. This suggests that the inter‐island channels must have been water‐filled at least by that date.
The development of near‐surface ground ice during the Holocene at sites near Mayo, Yukon Territory, Canada
Authors: Burn C. R. 
Published: February 2007

AbstractAn examination of soil thermal and hydrologic regimes at several sites near Mayo, Yukon Territory, and the ground‐ice stratigraphy of a thaw‐slump headwall close to these sites supports the hypothesis that an ice‐rich zone, frequently observed at the base of the active layer, may be due to the annual water balance of permafrost. Observations demonstrate that ice lenses have grown at the top of permafrost in soil tubes installed in 1983. In addition, 90 cm of segregated ice are exposed in the thaw‐slump headwall above a thaw unconformity, dated at 8870 ± 200 years BP, but below the base of the present active layer. These data suggest that the rate of water incorporation into permafrost over the last 8000 years in the Mayo area has been at least 0.1 mm yr−1.
Ancient and modern cold‐climate aeolian sand deposition: A review
Authors: Koster Eduard A. 
Published: February 2007

AbstractAlthough partly active aeolian sand sheets and dunes cover large areas in the zones of (dis)continuous permafrost, little precise information is available about the influence of cold‐climate conditions on modern aeolian processes. This means that palaeoenvironmental reconstructions in the stabilised, mainly Late Pleistocene dune fields and cover sand regions in the ‘sand belts’ of the European Lowlands and the Northern Great Plains of the USA and Canada, are necessarily still based on ancient evidence. Cold‐climate wind deposits are typically derived from areas of abundant sediment supply like unvegetated flood plains, glacial outwash plains, till plains and lake shores. The common parabolic and transverse dune forms resemble those observed in temperate regions. Although a variety of periglacial features has been identified in Late Pleistocene dune and cover sands none of them indicate that permafrost is crucial to aeolian activity. Specific structures in aeolian strata permit tentative interpretation of the moisture content of depositional sand surfaces, the nature of annual sedimentation cycles and the processes by which strata were deposited and/or contorted. But surprisingly little is known about the role of vegetation in the process of sand accumulation. Dunes are most informative with respect to reconstructions of past wind regimes, which offer important data for verification of palaeoclimatic simulations.
A reinterpretation of the Lateglacial environmental history of the Isle of Skye, Inner Hebrides, Scotland
Authors: Walker Michael J. C. , Ballantyne Colin K. , Lowe J. John , Sutherland Donald G. 
Published: February 2007

AbstractThis paper presents a major revision of the Late Devensian Lateglacial environmental history of the Isle of Skye, Scotland, based upon a combination of geomorphological, biostratigraphical and radiocarbon evidence. The distribution of glacial and periglacial landforms, and of raised shorelines, suggests that there was only one extensive readvance of local glaciers in southern Skye following the wastage of the Late Devensian ice sheet. Pollen‐stratigraphic evidence from 10 sites inside and 4 sites outside the mapped ice limits indicates that this readvance occurred during the Loch Lomond Stadial. At that time over 180km2of the uplands of south‐central Skye were covered by glacier ice, a much more extensive glaciation than previously envisaged. Palynological evidence from four Lateglacial profiles implies that degree of exposure to strong westerly winds was the principal factor determing vegetational contrasts on the island, and that regional differences in vegetational type were less pronounced than has hitherto been suggested. The glacial and palaeobotanical reconstructions reported here are more compatible with Lateglacial data from the Scottish mainland and Hebridean islands than were the previously‐published accounts for the Isle of Skye.
Late Quaternary sea‐level changes: Measurement, correlation, and future applications ‐ the international significance of IGCP Project 200
Authors: Shennan Ian 
Published: February 2007

AbstractInternational Geological Correlation Project 200 ran from 1983 to 1987 and was a major stimulus to sea‐level research. The results arising from the project were very varied, with much new data collected and analysed, but there remain some problems for international research.
Late Holocene sea levels in Ireland
Authors: Carter Richard W. G. , Devoy Robert J. N. , Shaw John 
Published: February 2007

AbstractThe course of Irish sea levels during the late‐Holocene is not well‐known, yet it is an understanding of this period that will prove crucial in the definition and management of future sea‐level changes. The coastline of Ireland embraces wide environmental and glacio‐isostatic contrasts, which serve and, to some extent, control sea‐level events at both local and regional scales, making definitive resolution of relative sea‐level changes difficult. In the southwest, the picture is of inexorable relative sea‐level rise. Studies in Co. Kerry show a gradual submergence of terrestrial facies, by estuarine and, in places, marine materials. Pollen and diatom studies, together with 14C dates, suggest a decreasing rate of relative sea‐level rise in the last 2500 years, often associated with geomorphological changes. Sites on the south coast of Ireland confirm the evidence from the southwest. In Cork Harbour, recent relative sea‐level rise since 2100 BP was responsible for marginal land submergence, while elsewhere rising water levels appear to have caused rapid barrier migrations and coast erosion. Palaeoenvironmental evidence from this region suggests a distinctive pattern of sea‐level change, associated with sedimentary and/or crustal dynamics, which is not encountered elsewhere in northwest Europe. The overall rate of relative sea‐level change on the south and southwest coasts falls between 0.6 and 1.1 mm/year over the last 5000 years. In the north, there is a clear east to west variation in relative sea‐level trends, following an isostatically‐controlled peak (+3 to −1 m OD) between 6500 BP (east) and 3500 BP (west). Falling sea levels from 3500 to 1500 BP have been followed by a general slow rise, although there are still local anomalies to this pattern, most noticeably at Malin Head, where sea level is currently falling at 2.4mm/year. Relative sea‐level signatures in Ireland differ markedly between the north and south coasts. Furthermore geomorphological and ecological contexts of this rise vary from east to west, providing a complex all‐Ireland framework for future investigations.
Holocene sedimentation on the North Norfolk barrier coast in relation to relative sea‐level change
Authors: Funnell Brian M. , Pearson Ian 
Published: February 2007

AbstractFourteen distinct sedimentary environments have been recognised in the surface sediments of the intertidal zone of the North Norfolk coast. Nine of these can be distinguished in borehole samples on the basis of sedimentological and micro‐palaeontological characteristics. They comprise: gravel; channel sand; intertidal sand; intertidal silty sand; intertidal mud and marsh creek; lower salt marsh; upper salt marsh; dune sand; and peat.Sediment accumulations have been penetrated to a depth of −8 m OD and basal peats dated by 14C back to 8410 ± 50 years BP. An overall rate of sediment accumulation (and subsidence) of about 1 m per thousand years is indicated. There is considerable persistence of sedimentary environments in the same areas during up‐building, but some erosion and roll‐over of the coastal barrier system has occurred. Evidence of positive and negative sea‐level tendencies are present in the record, but the main development of the tract is determined by sediment supply to the beach and marshes; positive sea‐level tendencies occur at c. 6610, 5970, 4630 and 2790 BP, negative sea‐level tendencies occur at 4520 to 4450 and (possibly) 3470 BP.
Loch Lomond Stadial and Flandrian shorelines in the inner Moray Firth area, Scotland
Authors: Firth Callum R. , Haggart B. Andrew 
Published: February 2007

AbstractMorphological mapping and stratigraphical investigations have identified surface and buried relict marine features in the inner Moray Firth area. The features consist of a buried gravel layer formed during the Loch Lomond Stadial, a buried beach of early Flandrian age, and surface beaches and estuarine flats of mid‐late Flandrian age. Analysis of the altitudes of morphological features has identified two buried and five (possibly six) surface glacio‐isostatically tilted raised shorelines. The steepest shoreline is associated with the buried gravel layer and slopes down towards N20°E at a gradient of 0.20m/km. Younger shorelines have lower gradients between 0.16–0.03m/km. The shoreline sequence combined with published data defines relative sea‐level movements in the area during the last 11000 years. The inner Moray Firth shorelines are correlated with similar features in other areas of Scotland which include the Main Lateglacial, Main Buried and Main Postglacial Shorelines.
Evidence of early Flandrian tidal surges in Lower Strathearn, Scotland
Authors: Cullingford Robin A. , Caseldine Christopher J. , Gotts Paul E. 
Published: February 2007

AbstractDetailed stratigraphic, palaeobotanical (diatom and pollen) and radiometric evidence from a sequence of buried estuarine deposits, buried peat and overlying estuarine ‘carse’ deposits at Wester Rhynd, in Lower Strathearn, suggests the occurrence of two brief marine incursions between the abandonment by the sea of a buried estuarine flat, probably the Low Buried Beach, at about 8765 ± 75 BP, and c. 8500 BP. The first incursion, shortly after 8565 ± 85 BP, caused bottom‐living marine diatoms to be thrown without clastic material onto the rapidly accumulating terrestrial peat. The second, bracketed by dates of 8485 ± 80 and 8510 ± 85 BP, deposited an extremely thin (1 mm) layer of fine sand that interrupts an otherwise unbroken buried peat succession covering the period 8765 ± 75 to 7710 ± 70 BP. The marine diatom, lithostratigraphic and 14C evidence together are consistent with a storm, storm‐surge or tsunami origin for these events, which are recognised principally from the diatom evidence, having left no mark in the pollen record.
Climatic changes in the Chalbi Desert, North Kenya
Authors: Nyamweru C. K. , Bowman D. 
Published: February 2007

AbstractThe Chalbi flat, located 60 km outside the rift to the east, forms a moist, salt‐clay encrusted playa which also functions as an inland sink for alluvial fans. Residual lacustrine beds, including freshwater carbonates and travertines, crop out along its higher periphery. Mammalian bones of lacustrine and terrestrial elements, and K/Ar dating of the capping lava suggest a lake or a swamp environment 2–2.5 million years ago. Radiocarbon dating of Melanoides tuberculata and Planorbis and a sediment assemblage composed of clotted micrite, calcareous molds, root marks and stromatolites point to an additional early Holocene Chalbi lake or swamps 11000‐9500 yr BP. The data suggest wet environmental conditions outside the rift, which is consistent with the occurrence of a wet period in the early to middle Holocene in intertropical Africa, but out of phase with the climatic conditions in Sinai and Israel and with the high‐latitude maximum lake levels and glacier advance. These relations have probably been caused by migration of climatic belts.