Showing papers in "Boreas in 2008"
June1
TL;DR: In this paper, a proposal for a common chronostratigraphical classification of the Quaternary in Norden (and partly continental NW Europe) is made, based on the sequence of glacials/interglacials.
Abstract: Principles and terminology for classification of the Quaternary are discussed, including lithostratigraphy, biostratigraphy. morphostratigraphy, climatostratigraphy and chronostratigraphy. The main conclusion is a proposal for a common chronostratigraphical classification of the Quaternary in Norden (and partly continental NW Europe). The Quaternary is subdivided into the Pleistocene and the Holocene Series. The Pleistocene is further subdivided into several provisional stages (Weichselian, Eemian, etc.), based on the sequence of glacials/interglacials. but with the boundaries preferably defined by stratotypes. The Late Weichselian and the Flandrian (Holocene) are subdivided into chronozoncs (Bolling, Older Dryas, Allerod, Younger Dryas, Preboreal, Boreal, Atlantic, Subboreal, Subatlantic) with the boundaries dcfined in conventional radiocarbon years.
1,103 citations
TL;DR: Single-grain Optically Stimulated Luminescence (OSL) as mentioned in this paper is a single-grain OSL method that can be used to determine whether a sample was bleached at deposition or not.
Abstract: Optical dating measures the time that has elapsed since mineral grains were exposed to daylight. The technique is ideal for sediments in which all the grains were exposed to sufficient daylight at deposition to reset the optically stimulated luminescence (OSL) signal. However, in many environments the exposure of individual grains to daylight will be variable. Limited exposure to light results in grains retaining a part of any prior trapped charge, and if unaccounted for this causes overestimation of the age. In the past 15 years it has become feasible to control the number of grains used for each luminescence measurement, varying from many thousands to a single grain. Where many grains are measured simultaneously, the luminescence signal is averaged, and any variability in resetting between grains will be obscured. This article describes the methods involved in single-grain OSL measurements and review the application of the method to glacial, fluvial and aeolian Quaternary sediments. Single-grain OSL is expanding the range of environments that can be dated and improving the reliability of ages by explicitly assessing whether samples were bleached at deposition or not.
479 citations
TL;DR: In this article, the application of optically stimulated luminescence (OSL) dating to fluvial deposits is discussed with respect to its potential to provide important contributions to research in the fields of geomorphology, palaeoseismology and archaeology.
Abstract: Fluvial deposits and landforms are important archives of river response to climate, tectonics and base level change and are commonly associated with archaeological sites. Unlike radiocarbon dating, the target material for optically stimulated luminescence (OSL) dating (sands and silts) is nearly ubiquitous in fluvial deposits and the age range for OSL spans the last glacial–interglacial cycle, a time period of interest to many Quaternary scientists. Recent advances in OSL techniques and the development of single-grain dating capabilities have now allowed fluvial deposits, and other deposits commonly afflicted with incomplete zeroing of the luminescence signal, to be dated. The application of OSL dating to fluvial deposits is discussed with respect to its potential to provide important contributions to research in the fields of geomorphology, palaeoseismology and archaeology. Examples are given from each research field.
309 citations
TL;DR: In this article, a long, continuous pollen diagram covering the interval from the Late Rissian to the Holocene was found in the ancient lake of Les Echets, 15 km northeast of Lyon, France, which is correlated with the Early Wiirmian trilogy Amersfoort-Brorup-Odderade.
Abstract: Analysis of 732 samples through 39 m of sediments from the ancient lake of Les Echets, 15 km northeast of Lyon, France, resulted in a long, continuous pollen diagram covering the interval from the Late Rissian to the Holocene. Above a complete Ecmian sequence, there are two Early Wiirmian temperate cycles (the older one including two climatic optima separated by a brief deterioration) with forest successions characterized by the spread of Carpinus at the end of the early temperate phase. These episodes, whose exact equivalents are found at Grande Pile in the Vosges area, are correlated with the Early Wiirmian trilogy Amersfoort-Brorup-Odderade of northern Europe. The absolute dates proposed for the Grande Pile sequence arc accepted, whereas those for the three northern European stratotypes are rejected. The Early Wiirmian is thus placed between 115,000 and 70,000 years B.P. In the Middle Wiirm, three undated intcrstadials arc characterized by a sparse forest cover. The long Late Wiirmian section is a characteristic feature of the sediment history at Les Echets. Very cold and arid conditions prevailed during this interval, without any unequivocal indications of intcrstadial episodes. A rise in Artemisia around 15,000 B.P. marks the transition from the Pleniglacial to the Oldest Dryas.
270 citations
TL;DR: In this paper, the authors reconstructed lake-level fluctuations in Lake Bysjon from recorded changes in the sediment limit and the content of reworked minerogenic matter in sediment, which are related to past lake level fluctuations by correlation to fluctuations convincingly demonstrated in earlier studies.
Abstract: Holocene lake-level fluctuations in Lake Bysjon are reconstructed from recorded changes in the sediment limit and the content of reworked minerogenic matter in the sediment. These recorded changes are related to past lake-level fluctuations by correlation to fluctuations convincingly demonstrated in earlier studies. A correlation of regionally significant fluctuations in South Sweden is presented, and the climatic interpretation is discussed. A distinct lowering in lake level culminated at about 9,500-9,200 B.P., recording a major period of drier climate in the earlier part of the Holocene. After a succeeding period of increased humidity, recorded by rising and relatively higher lake level, another major period of increased dryness began at about 6,800-6,500 B.P. In contrast to the older period, the climate was not uniformly drier, but anumber of demonstrated lake-level fluctuations suggest a fluctuating climate. From the reconstruction in Bysjon, dryness culminated at about 4,900-4,600 B.P., and the major period lasted until about 2,900-2,600 B.P. After a succeeding rise in lake level, another distinct lowering is recorded some time between 1,800 B.P. and 1,200 B.P.
268 citations
TL;DR: A detailed lateglacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator 14C dates on terrestrial plant macrofossils.
Abstract: A detailed late-glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator 14C dates on terrestrial plant macrofossils. Two plateaux of constant.,14C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these plateaux for palaeo-ecological investigations are threefold: (1) a more refined 14C dating within the plateaux is not possible, (2) in teleconnections between different sites (if based on 14C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a plateau of constant age, and (3) exact time-depth relationship and therefore influx calculations are made impossible during these plateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.
258 citations
TL;DR: Wintle, A. G. as discussed by the authors, where it has been and where it is going, 2007; Boreas, 37(4), 471-482; Wintle et al. (2008).
Abstract: Wintle, A. G. (2008). Luminescence dating: where it has been and where it is going. Boreas, 37(4), 471-482.
241 citations
TL;DR: The application of luminescence methods requires an understanding of the nature of glacial and associated environments to select the most appropriate sediment samples for dating as mentioned in this paper, which requires careful sampling and descriptions of the sampling site, testing for insufficient bleaching and modelling dose rate variability.
Abstract: Dating glacial and associated sediments is essential to provide a temporal framework for accurate reconstructions of past climatic conditions and for helping to determine the nature and magnitude of glaciation for landscape evolution studies. There are few widely applicable, accurate and precise methods available to date Quaternary landforms and sediments, despite the numerous numerical dating methods that are currently available. Furthermore, there are few methods that can be utilized for the whole of the late Quaternary (c. 125 kyr ago to present). Recent developments in luminescence dating, however, are providing opportunities to date a broad range of late Quaternary glacial and associated landform sediments. The application of luminescence methods requires an understanding of the nature of glacial and associated environments to select the most appropriate sediment samples for dating. Problems associated with luminescence dating of glacial sediments include insufficient bleaching, low sensitivity of quartz, and variable dose rates during the history of the sediment due to changing water content or nuclide leaching. These problems can be overcome by careful sampling and descriptions of the sampling site, testing for insufficient bleaching and modelling dose rate variability.
232 citations
TL;DR: In this paper, the authors constructed a glaciation curve for the Late Weichselian in the northern North Sea, based on new data from the Fladen, Sleipner and Troll areas, combined with earlier published results, and suggested that the maximum extent of the last glaciation along the NW European seaboard from the British Isles to northern Norway was prior to c. 22 ka BP.
Abstract: Based on new data from the Fladen, Sleipner and Troll areas, combined with earlier published results, a glaciation curve for the Late Weichselian in the northern North Sea is constructed. The youngest date on marine sedimentation prior to the late Weichselian maximum ice extent is 29.4 ka BP. At this time the North Sea and probably large parts of southern Norway were deglaciated (corresponding to the Alesund interstadial in western Norway). In a period between 29.4 and c. 22 ka BP, the northern North Sea experienced its maximum Weichselian glaciation with a coalescing British and Scandinavian ice sheet. The first recorded marine inundation is found in the Fladen area where marine sedimentation started close to 22 ka BP. After this the ice fronts receded both to the east and west. The North Sea Plateau, and possibly parts of the Norwegian Trench, were ice-free close to 19.0 ka, and after this a short readvance occurred in this area. This event is correlated with the advance recorded at Dimlington, Yorkshire, and the corresponding climatostratigraphic unit is denoted the Dimlington Stadial (18.5 ka to 15.1 ka). The Norwegian Trench was deglaciated at 15.1 ka in the Troll area. The data from the North Sea, together with the results from Andwa, northern Norway (Vorren et al. 1988; Moller et al. 1992), suggest that the maximum extent of the last glaciation along the NW-European seaboard from the British Isles to northern Norway was prior to c. 22 ka BP.
215 citations
TL;DR: In this paper, detailed pollen and 18O/16O studies on two sediment profiles from small Swiss lakes are reported, showing that the isotope ratio in rain and snow is correlated to temperature.
Abstract: Results from detailed pollen and 18O/16O studies on two sediment profiles from small Swiss lakes are reported. 18O/16O records in lacustrine carbonate contain paleoclimatic information because they reflect mainly the isotope ratio in rain and snow which is correlated to temperature. Several transitions between different climatic periods determined palyno-logically are also indicated by marked changes in the isotope ratios in both profiles, namely the transitions Oldest Dryas - Boiling and Allerod - Younger Dryas - Preboreal. 18o/16O was 2 to 3 %0 lower during Younger Dryas than during the adjacent periods, corresponding to a temperature drop of a few degrees Centigrade according to a tentative estimate.
203 citations
TL;DR: In this article, a suite of 24 Norwegian Sea cores were used to derive sea-surface temperatures for the last glacial maximum (18,000 B.P.), the last interglacial (120,000 b.P.).
Abstract: Synoptically mapped faunal abundance and faunal composition data, derived from a suite of 24 Norwegian Sea cores, were used to derive sea-surface temperatures for the last glacial maximum (18,000 B.P.), the last interglacial (120,000 B.P.), and isotope stage 5a (82,000 B.P.). Surface circulation and ice cover reconstructions for these three times, deduced from the sea-surface temperatures, suggest the following conclusions: (1) During glacial periods, Norwegian Sea surface circulation formed a single, sluggish, counterclockwise gyre that was caused by wind drag on the ubiquitous sea ice cover; (2) the last interglacial was characterized by a circulation pattern similar to that of today except that the two counterclockwise gyres were displaced toward the east and were more vigorous than they are today. This circulation pattern forced the Norwegian Current into a position close to the coast of Norway and permitted formation of a strong east-west temperature gradient close to the Scandinavian landmass; (3) interglacial periods prior to 120,000 B.P. had similar climatic conditions to the 82,000 B.P. level and were characterized by a weak two-gyre circulation pattern. The southern gyre, driven by wind stress in summer months, was ice covered in winters. The northern gyre had little open water even in summers and was primarily formed by wind drag on sea ice. Atmospheric modifications resulting from these circulation patterns and sea ice conditions produced varying climatic conditions in Scandinavia during interglacials prior to the Holocene. The climate was probably warmer and moister during the last interglacial (Eemian) than it is today. Other interglacials during the last 450,000 years, but prior to the Eemian, were probably colder and drier as the Norwegian Sea was not an important source of heat and moisture.
TL;DR: In this paper, the authors concluded that shell dates are reliable when handled carefully and gave apparent ages from 340±75 to 550±80 years, indicating that apparent age is not a significant problem in dating of Norwegian shells.
Abstract: General problems in determining and interpreting shell C14 dates are discussed: calculation methods, factors influencing primary activity (apparent age), and determination of contamination. It is concluded that shell dates are reliable when handled carefully. Measurements on ten shells, collected between 1898 and 1923 on the Norwegian coast, gave apparent ages from 340±75 to 550±80 years, indicating that apparent age is not a significant problem in dating of Norwegian shells.
TL;DR: Lowe and Walker as discussed by the authors as discussed by the authors described a book called Reconstructing Quiiternary Environments, which describes the process of constructing quaternary environments, and reviewed in this article.
Abstract: Book reviewed in this article:
Lowe J J & Walker M J C 1984 Reconstructing Quiiternary environments
TL;DR: In this paper, rates of peat formation and degrees of humification were determined in two peat sections based on 59 calibrated C-14 dates, and accumulation rates during the last 6500 years of 0.16 to 0.80 mm/year were found.
Abstract: In the raised bog Draved Mose, rates of peat formation and degrees of humification were determined in two peat sections. Based on 59 calibrated C-14 dates, accumulation rates during the last 6500 years of 0.16 to 0.80 mm/year were found. The peat layers were analyscd for Sphagnum species, rhizopods, and pollen and spores. A clear relation between humification degrees and humidity at the time of formation was found, while the relation between measured growth rates and degrees of humification varied throughout the 2.5 m thick peat section. These variations are thought to be mostly a result of autocompaction.
TL;DR: In this paper, a Schmidt hammer was used in conjunction with lichenometry to examine the relative age of the outermost Neoglacial moraines in front of glaciers in the Jotunheimen mountains of southern Norway.
Abstract: A Schmidt hammer was used in conjunction with lichenometry to examine the relative age of the outermost Neoglacial moraines in front of glaciers in the Jotunheimen mountains of southern Norway. Particular attention was directed at (1) the magnitude of the ‘Little Ice Age’ glacier expansion episode relative to any others of Neoglacial age, and (2) the potential and limitations of the Schmidt hammer in the context of Holocene glacial chronologies. Schmidt hammer R-values were measured at 34 glaciers and the sizes of the lichen Rhizocarpon geographicum agg. at 80 glaciers. Unusually low R-values and large lichens suggest the occurrence of pre- ‘Little lee Age’ Neoglacial moraines at only a small minority (< 10 %) of the sampled glaciers. The traditional model of relatively large southern Norwegian glaciers during the ‘Little Ice Age’ is substantiated and it is tentatively suggested that differences in climate or glacier type may account for a regional difference in the status of the ‘Little Ice Age’ between northern and southern Scandinavia. The incorporation of weathered boulders into ‘Little Ice Age’ moraines by glacier push mechanisms, and the altitudinally-related variation in boulder surface textures, are identified as major sources of potential error in the use of the Schmidt hammer R-values for relative-age determination of Neoglacial surfaces.
TL;DR: Roberts, H. M. as mentioned in this paper described the development and application of luminescence dating to loess deposits: a perspective on the past, present and future. Boreas 37(4), 483-507.
Abstract: Roberts, H. M. (2008). The development and application of luminescence dating to loess deposits: a perspective on the past, present and future. Boreas 37(4), 483-507.
TL;DR: The tsunami was identified in the sedimentary record as an erosional unconformity overlain by graded or massive sand with shell fragments, followed by redeposited organic detritus as mentioned in this paper.
Abstract: The statigraphy in 25 coastal lakes shows that most of the Norwegian coastline was impacted by a large tsunami about 7200 14C BP. The methodology has been to core a staircase of lake basins above the contemporary sea level in several areas and to map the tsunami deposit to its maximum elevation. The tsunami was identified in the sedimentary record as an erosional unconformity overlain by graded or massive sand with shell fragments, followed by redeposited organic detritus. The greatest recorded runup along the coast (10–11 m above high tide) is found in areas most proximal to the Storegga slide scar on the Norwegian continental slope (Sunnmore). To the north and south, runup is less, about 6–7 m at Bjugn (250 km north of Sunnmore) and about 3–5 m in Austrheim (200 km to the south of Sunnmerre). This runup pattern supports the suggestion that the tsunami was generated by the Second Storegga Slide. The recorded runup heights are consistent within and between the investigated areas, and imply that the tsunami wave was not significantly influenced by the local topography, suggesting a very long wave length. The mapped runup estimates are in good agreement with a numerical model of the tsunami generated by the Second Storegga slide, and indicate that the slide was a single major event rather than a set of smaller slides.
TL;DR: In this article, a total of 15 organic-rich sediment samples, obtained from sites in Corsica and the Southern European Alps, was treated using both dense-media separation and the conventional preparation method in order to compare the relative efficiencies of the two methods.
Abstract: Dense-media separation, frequently adopted as a standard pollen extraction method for use with minerogenic sediment samples, was adapted for use with organic-rich sediment and peat samples. A total of 15 organic-rich sediment samples, obtained from sites in Corsica and the Southern European Alps, was treated using both dense-media separation and the conventional preparation method in order to compare the relative efficiencies of the two methods. The dense-media separation method consistently achieved a remarkably higher purity of extracted pollen grains. This was especially true for the Corsican peat samples, the dense-media separations being quite pure, whereas the classical method produced samples that were so severely polluted with organic fragments that it was impossible to carry out a satisfactory pollen analysis. The percentage values of each taxon were generally similar using both methods, showing that the two methods are compatible for pollen analytical studies. Total pollen concentrations were generally higher with the dense-media separation method (especially for gyttja samples). In conclusion, dense-media separation is an efficient method for pollen extraction from organic as well as from minerogenic sediments and deposits.
TL;DR: An improved crust-freeze sampler for taking undisturbed cores of the surface sediments from ice-covered lakes is described in this article, together with a technique for subsampling the frozen sediment.
Abstract: An improved crust-freeze sampler for taking undisturbed cores of the surface sediments from ice-covered lakes is described together with a technique for subsampling the frozen sediment. Hints are given on how photography and varve-counting in frozen and in fresh cores of varved lake sediments can be made easier, and on how to make thin sections of sediments for examination under the light microscope
TL;DR: The southwestern part of the Laurentidc Ice Sheet, in central North America, repeatedly surged during the last part of Wisconsin Glaciation as mentioned in this paper, and evidence includes the extreme lobation of the ice margin, the gentle slopes of lateral moraines and other marginal features, a radiocarbon chronology indicating extremely rapid marginal advance and retreat, and abundance of supraglacial flow till.
Abstract: The southwestern part of the Laurentidc Ice Sheet, in central North America, repeatedly surged during the last part of the Wisconsin Glaciation. Evidence includes the extreme lobation of the ice margin, the gentle slopes of lateral moraines and other marginal features, a radiocarbon chronology indicating extremely rapid marginal advance and retreat, and the abundance of supraglacial flow till. Rapid ice movement was caused by subglacial water and was probably limited to areas of slowly permeable substrate, which slowed the escape of the water.
TL;DR: In this paper, the authors show that the strongest early Holocene uplift occurs over northeastern Spitsbergen and eastern Nordaustlandet, falling both to east and west, and that the centre of uplift migrates to the southeast during the Holocene.
Abstract: The popular concept of a Late Weichselian ice sheet covering the Barents Shelf and confluent with the Scandinavian and Russian ice sheets is based primarily on the 6500 B.P. isobase which rises to the east over Spitsbergen, and to the west over Franz Joseph Land. Analysis of uplift curves from the Spitsbergen archipelago shows, however, that the strongest early Holocene uplift occurs over northeastern Spitsbergen and eastern Nordaustlandet, falling both to east and west, and that the centre of uplift migrates to the southeast during the Holocene. Direct evidence of glacier fluctuation indicates an important Billefjorden Stage of glaciation at about 11,000 to 10,000 B.P., part of whose extent can be defined by moraines and by abrupt changes in the marine limit. The dominant ice masses of the Billefjorden Stage seem to have formed over eastern Spitsbergen, Edgeoya, Barentsoya and southern Hinlopenstretet, and it is the decay of this ice mass which is primarily responsible for the pattern of early Holocene uplift.
Stratigraphic evidence suggests the absence of an important glacial event at 18,000–20,000 B.P., but an important phase of Spitsbergen-centred glaciation at about 40,000 B.P., and a glacial phase at 80,000–120,000 B.P. It is suggested that many raised beach sequences outside the Billefjorden readvance show an upper sequence related to deglaciation at about 40,000 B.P., and a lower, Holocene sequence related to decay of the Billefjorden ice. The anomalous pattern of late Holocene uplift may be related to restrained rebound produced by regeneration of ice on the main islands of the archipelago and unrestrained rebound on Hopen and Kong Karls Land, which were incapable of sustaining large ice masses of their own.
A pattern of LateGlacial climatic circulation which may have produced ice masses on the east coast of Spitsbergen, west coast of Novaya Zemlya and north coast of Russia is suggested. It is also suggested that this pattern of glaciation produced features which have been wrongly interpreted as evidence of a Barents ice sheet.
TL;DR: In this paper, a subglacial till formed from a sandstone bedrock has a variable grain-size distribution which reflects its variable genesis, and the experiments indicate that most of the sand-sized till material formed as a result of crushing, while the silt is mainly the result of abrasion.
Abstract: A subglacial till formed from a sandstone bedrock has a variable grain-size distribution which reflects its variable genesis. Glacial comminution processes were simulated by artificial mill experiments with fragments of the sandstone bedrock. Pure crushing caused disintegration along mineral boundaries into separate minerals, most mineral grains retaining their primary size during the crushing process. Abrasion produced cracks across the minerals and resulted in silt-sized rock flour. The experiments indicate that most of the sand-sized till material formed as a result of crushing, while the silt is mainly the result of abrasion. The sand and silt are both regarded as components resistant to further glacial comminution, but are formed by different comminution processes. By considering also the coarser till material, the general principles of glacial breakdown of resistant rocks from boulders to sand or silt can be illustrated. A matrix index and an abrasion index based on the mill experiments distinguish well between genetically different subglacial till types
TL;DR: In this article, a 5.5m long sequence of cores from lake AErasvatnet has been investigated for lithostratigraphy, micro-and macro-fossils and radiocarbon chronology.
Abstract: Cores representing a 5.5m long sequence recovered from lake AErasvatnet have been investigated for lithostratigraphy, micro- and macrofossils and radiocarbon chronology. For the first time in Fennoscandia the maximum Weichselian advance has been closely bracketed with radiocarbon datings (19,000–18,500 B.P.). A continuous stratigraphy from 18,500 B.P. and onwards, partly marine and partly lacustrine, discloses the local shoreline displacement, the palaeovegetation, the palaeoclimate and, together with other data, the deglaciation history. Two phases with a prevailing High Arctic climate have occurred: 18,000 to 16,000 B.P. and 13,700 to 12,800 B.P. Important climatic amelioration accelerating the deglacial recession occurred 16,000, 12,800 and 12,000 B.P. The continental ice sheet was situated close to its maximum position until about 16,000 B.P. The following deglaciation was interrupted by (a minor ?) readvance/halt about 15,000 B.P. (the Flesen event), 13,700-13,000 B.P. (the D-event), 12,500 B.P. (the Skarpnes event) and 11,000–10,000 B.P. (the TromsO-Lyngen event). The deglaciation chronology and pattern can be correlated with the suggested deep-sea-stratigraphy-based stepwise pattern relying on the old age alternative for termination IA.
TL;DR: Based on radiocarbon dates from shells, vertebrate bones and limnic sediments, a revised deglaciation chronology is presented in this article, supported by biostratigraphic transects of time-space diagrams.
Abstract: Because of its well-developed ice-marginal zones, SW Sweden is an important reference area for the study of deglaciation, chronology and palaeoclimate 13,500-10,000 B.P. The ice-marginal zones are described and defined. Earlier research and opinions concerning the deglaciation are summarized. Based on radiocarbon dates from shells, vertebrate bones and limnic sediments, a revised deglaciation chronology is presented. This chronology is supported by biostratigraphic transects of time-space diagrams. The radiocarbon and varve chronologies are compared. Some ice-marginal zones are supposed to be 400 to 900 years older than expected from the varve chronology. The deglaciation chronology is correlated within the southern margin of the Scandinavian inland ice. Various consequences for the interpretation of glacial dynamics, shoreline displacement, and the biological environment are mentioned.
TL;DR: In this paper, the authors compare the environmental inferences that can be made from fossil Coleoptera with those made from palynological data in the Glanllynnau kettle hole and show that during this period there was only one climatic oscillation and that this differed in both timing and intensity from oscillations inferred from Palynological evidence.
Abstract: This investigation was designed to compare the environmental inferences that can be made from fossil Coleoptera with those that can be made from palynological data. In the Glanllynnau kettle hole, sedimentation began at 14,000 BP and continued until about 10,000 BP. The Coleoptera from these deposits show that during this period there was only one climatic oscillation and that this differed in both timing and intensity from oscillations inferred from palynological evidence. Thus, at about 13,000 BP, an intensely cold continental climate suddenly gave place to a period with summer temperatures at least as warm as those at the present day, but during this episode the landscape was entirely without trees. From 12,000 BP to about 10,000 BP there was a progressive deterioration in the temperature, and the period of Betula forest, broadly equivalent to the Allerod, is shown to have a less thermophilous fauna than that of the previous pollen Zone I. An attempt is made to explain this anomaly in terms of the differential rate of response of the plants and animals to rapid climatic changes.
TL;DR: The characteristically digested teeth from diurnal predator pellets may provide the only direct indication of the origin of at least a part of the mammalian material contained in deposits formed in open sedimentary environments where skeletal parts have been dissociated.
Abstract: Differences between the remains of mammalian prey in pellets of diurnal and nocturnal avian predators are discussed on the basis of recent material and in relation to probable fossil occurrences. The ability of diurnal predators to digest bone reduces the value of their pellets for quantitative or qualitative indications of the regional mammalian fauna. However, the remaining partially digested fragments in pellets of diurnal predators appear to have a characteristic morphology which may be recognised in a sample of fossil mammalian teeth from the type Cromerian Upper Freshwater Bed sediments at West Runton, England. The implications of such an origin for faunal analysis are briefly considered.
This is believed to be the first time that the role of diurnal predatory birds in accumulation of fossil vertebrate material has been recognised. The characteristically digested teeth from diurnal predator pellets may provide the only direct indication of the origin of at least a part of the mammalian material contained in deposits formed in open sedimentary environments where skeletal parts have been dissociated.
TL;DR: In this paper, a detailed tephrostratigraphy of the sediments from Lake Torfadalsvatn in northern Iceland is presented, which can act as a refined dating and correlation tool in the North Atlantic region and enable calibration between different absolute chronologies.
Abstract: High resolution environmental records with a refined chronology are essential to understand, reconstruct and model the climate dynamics of the last glacial-interglacial transition. Sediments from Lake Torfadalsvatn in northern Iceland contain at least four primary volcanic tephras that belong to ash zone I in the North Atlantic deep-sea cores. We chemically define these basaltic/rhyolitic tephras and the high resolution allows us to date them to about 10,800, 10,600, 9300 and 8900 BP. This detailed tephrostratigraphy will act as a refined dating and correlation tool in the North Atlantic region and enable calibration between different absolute chronologies. The pollen stratigraphy of the sediments suggests that by 10,400 14C years BP plant colonization of coastal north Iceland had begun. The pollen stratigraphy shows a succession of pioneer plants, from open tundra vegetation towards birch-juniper woodland, which probably also reflects a transition from a cool climate at 10,400 BP to conditions similar to today's sub-polar oceanic climate around 9200 BP. Diatom data largely concur with the climatic information from pollen, indicating gradually increasing productivity in the lake.
TL;DR: The Veikimoraines in northernmost Sweden display a very conspicuous distribution pattern, sharply demarcated to the east and successively decreasing to the south, west and north as discussed by the authors.
Abstract: The Veikimoraines in northernmost Sweden display a very conspicuous distribution pattern, sharply demarcated to the east and successively decreasing to the south, west and north. The sharp demarcation to the east is thought to reflect the front of a stagnant ice sheet. The downwasting of this glacier was retarded by the insulation of a thick superglacial debris cover and subarctic vegetation invaded at least parts of the slowly collapsing ice. Radiocarbon datings of organic matter deposited in connection with the formation of the Veiki moraine, lithostratigraphical evidence and the relation to other glacial features prove the Veiki moraine landscape to date from the deg laciation of the first Weichselian ice sheet, i.e. the Perapohjola Interstadial. The good preservation of the features implies that in extensive areas of northern sweden the Early Weichselian glacial landscape escaped significant erosion despite being overrun by two later glaciers. Previous interpretations of the Late Weichselian/Holocene deglaciation are largely based on an Early Weichselian deglaciation pattern.
TL;DR: Radiodensiometric-dendroclimatological conifer cronologies from Lapland (Scandinavia) and the Alps (Switzerland) are presented in this paper.
Abstract: Radiodensiometric-dendroclimatological conifer cronologies from Lapland (Scandinavia) and the Alps (Switzerland).
TL;DR: A complete interglacial cycle, named the Fjosangerian and correlated with the Eemian by means of its pollen stratigraphy, is found in marine sediments just above the present day sea level outside Bergen, western Norway as mentioned in this paper.
Abstract: A complete interglacial cycle, named the Fjosangerian and correlated with the Eemian by means of its pollen stratigraphy, is found in marine sediments just above the present day sea level outside Bergen, western Norway. At the base of the section there are two basal tills of assumed Saalian (sensu lato) age in which the mineralogy and geochemistry indicate local provenance. Above occur beds of marine silt, sand and gravel, deposited at water depths of between 10 and 50 m. The terrestrial pollen and the marine foraminifera and molluscs indicate a cold-warm-cold sequence with parallel development of the atmospheric and sea surface temperatures. In both environments the flora/fauna indicate an interglacial climatic optimum at least as warm as that during the Holocene. The high relative sea level during the Eemian (at least 30 m above sea level) requires younger neotectonic uplift. The uppermost marine beds are partly glaciomarine silts, as indicated by their mineralogy, drop stones and fauna, and partly interstadial gravels. The pollen indicates an open vegetation throughout these upper beds, and the correlation of the described interstadial with Early Weichselian interstadials elsewhere is essentially unknown. The section is capped by an Early Weichselian basal till containing redeposited fossils, sediments, and weathering products. Several clastic dikes injected from the glacier sole penetrate the till and the interglacial sediments. Radiocarbon dates on wood and shells gave infinite ages. Amino acid epimerization ratios in molluscs support the inferred Eemian age of the deposit. The Fjosangerian is correlated with the Eemian and deep sea oxygen isotope stage 5e; other possible correlations are also discussed.