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This paper reports the results of new malacological analyses from a thick tufa sequence at Direndall (Luxembourg). The study is temporally contextualised with radiocarbon dates and an age–depth model. The malacological study focuses on species associations to reconstruct palaeoenvironmental developments. The gradual appearance of several shade-demanding species reflects the expansion of forest environments during the early Holocene. After c. 7.5 cal. kyr BP, three phases of maximal expansion of shade-demanding species are interspersed with two phases of decline of these taxa dated between c. 7.1 and 6.5 cal. kyr BP and between c. 3.5 and 2.4 cal. kyr BP. Malacological data are discussed with previously published calcite stable isotope data from the same sequence. Strong correlations between malacological data and δ13C profile are highlighted over the whole sequence. Combined influences of local environmental conditions and regional climatic trends are emphasised. The sequence provides a palaeoenvironmental succession free of any anthropic influence. [ABSTRACT FROM AUTHOR]

This paper describes long-term changes in human population and vegetation cover in southern France, using summed radiocarbon probability distributions and site count data as population proxies and information from fossil pollen cores as a proxy for past land cover. Southern France is particularly well-suited to this type of study as a result of previous programmes of intensive survey work and excavation in advance of large-scale construction. These make it possible to calibrate the larger scale occupation patterns in the light of the visibility issues created by the burial of archaeological sites beneath alluvial sediments. For purposes of analysis, the region was divided into three biogeographical zones (BGZ), going from the Mediterranean coast to the middle Rhône valley (MRV). All the different population proxies in a given zone show broadly similar patterns of fluctuation, though with varying levels of resolution. The long-term patterns in the different zones all show significant differences from the overall regional pattern, but this is especially the case for the non-Mediterranean middle Rhône area. Cluster analysis of pollen samples has been carried out to identify the main regional land cover types through the Holocene, which are increasingly dominated by open types over time. A variety of other pollen indicators show evidence of increasing human impact through time. Measures of human impact correlate strongly with the population proxies. A series of thresholds are identified in the population–human impact trajectory that are related to other changes in the cultural sequence. The lack of independent climate data for the region means that its impact cannot currently be assessed with confidence. However, for the later periods, it is clear that the incorporation of southern France into larger regional systems played a major role in accounting for changes in land cover and settlement. [ABSTRACT FROM AUTHOR]

Geological investigations of coastal sediment sequences play a key role in verifying earthquake and tsunami characteristics inferred from historical records. In this paper, we present a multi-proxy investigation of a coastal lowland site facing the Nankai-Suruga megathrust and appraise evidence for tsunamis and earthquake-triggered terrestrial mass movements occurring over the last 800 years. Combining a high-resolution chronology with X-ray computed tomography and analyses of particle size, diatoms, pollen, non-pollen palynomorphs and aerial photographs, we present the most compelling geological evidence of the 1361 CE Kōan (also known as Shōhei) tsunami reported to date from any site along the megathrust. This finding is consistent with either of two recent hypotheses: a single larger rupture of both the Nankai and Tōnankai regions or two smaller ruptures separated by a few days. Enhancing the site chronology using Bayesian age modelling, we verify evidence for inundation during the 1498 CE Meiō tsunami. While previous investigations identified evidence for historically recorded tsunamis in 1605, 1707 and 1854 CE and a storm surge in 1680 or 1699 CE, we encountered a thick sand layer rather than discrete extreme wave deposits in this interval. The overprinting of evidence highlights the potential for geological records to underestimate the frequency of these events. A terrestrial mass movement also deposited a sand layer at the site; radionuclide dating and aerial photographs provide independent confirmation that this may have been triggered by intense shaking in 1944 CE during the most recent great Nankai-Suruga megathrust earthquake. [ABSTRACT FROM AUTHOR]

Recent research in northern Iceland has highlighted a significant period of rock slope instability during the early Holocene due to the combined effects of postglacial rebound, relative sea-level fall, and glacially oversteepened mountain slopes. Using the Vatn landslide (Skagafjörður, central northern Iceland) as an example, this paper focuses on this period and describes the sequence of events that led to landsliding. Geomorphic mapping, stratigraphical evidence, and both radiocarbon and tephra dating were applied. Collectively, the data acquired indicate that the landslide occurred between 11,400 and 10,790 cal. yr BP. However, while rock slope failure represents a significant disintegration of mountain slopes, this study suggests that large postglacial landslides might also play a role in arresting sediment transport from other hillslope processes rather than contributing large volumes of sediment. [ABSTRACT FROM AUTHOR]

The transformation of natural landscapes in Middle Europe began in the Neolithic as a result of the introduction of food-producing economies. This paper examines the relation between land-cover and demographic change in a regionally restricted case study. The study area is the Western Lake Constance area which has very detailed palynological as well as archaeological records. We compare land-cover change derived from nine pollen records using a pseudo-biomisation approach with 14C date probability density functions from archaeological sites which serve as a demographic proxy. We chose the Lake Constance area as a regional example where the pollen signal integrates a larger spatial pattern. The land-cover reconstructions for this region show first notable impacts at the Middle to Young Neolithic transition. The beginning of the Bronze Age is characterised by increases of arable land and pasture/meadow, whereas the deciduous woodland decreases dramatically. Changes in the land-cover classes show a correlation with the 14C density curve: the correlation is best with secondary woodland in the Young Neolithic which reflects the lake shore settlement dynamics. In the Early Bronze Age, the radiocarbon density correlates with open land-cover classes, such as pasture, meadow and arable land, reflecting a change in the land-use strategy. The close overall correspondence between the two archives implies that population dynamics and land-cover change were intrinsically linked. We therefore see human impact as a key driver for vegetation change in the Neolithic. Climate might have an influence on vegetation development, but the changes caused by human land use are clearly detectable from Neolithic times, at least in these densely settled, mid-altitude landscapes. [ABSTRACT FROM AUTHOR]

Holocene climate change caused disturbances of the Central African rainforest belt, with decrease in forest area during drier conditions followed by expansion during wetter periods. Today, human impact is a driver for forest degradation in the Congo Basin. For assessing the quality and quantity of forest degradation, information on biodiversity and carbon stocks from reference ecosystems is needed which (1) were not affected by Holocene climate change and (2) lack direct human impacts like logging or shifting cultivation. The Birougou Mountains in Gabon, which were devoid of direct human impact over the last centuries, may resemble such a reference ecosystem. This paper tests the hypothesis that the Birougou Mountains served as refugium for rainforest vegetation during periods of Holocene climate change. For 34 forest plots within the Birougou Mountains and 27 savannah plots within an adjacent forest savannah mosaic, we present stable carbon isotope data from current vegetation cover, organic inputs to soil organic carbon (SOC), bulk SOC and the humic acid fraction of SOC. Additionally, we estimated the mean age of the SOC humic acid fraction by 14C dating. The data indicated a continuous forest cover in the Birougou Mountains since – at least – the Holocene climate optimum, but a change from forest to savannah vegetation in the forest savannah mosaic. Results confirm the forest of the Birougou Mountains as a refugium of rainforest vegetation and suitable reference for the natural potential regarding biodiversity and ecosystem carbon stocks. [ABSTRACT FROM AUTHOR]

A high-resolution paleosecular variations record since ~6 kyr, including direction and relative intensity, was derived from the Pearl River delta (PRD) sediments in southern China constrained by the radiocarbon ages in this paper. The comparison of both direction and relative intensity with other adjacent records confirmed that the non-dipole field has common fluctuations in the centennial to millennial timescales. This pattern provides some profound tied points to correlate the sediment sequence in the different deposition environments. The significant age offsets of the similar secular variation features between the different records corroborate the radiocarbon errors in dating the sediments. This work further showed that the geomagnetic secular variations can serve as an effective tool to determine the sediments’ age and correlate the stratigraphy for the different deposition environments in a wide region. [ABSTRACT FROM PUBLISHER]

It has been argued that Central European lake levels were driven by solar activity. This interpretation rests on the comparison of a score record of radiocarbon dates with the 14C residual curve. This score record is a variant of a cumulative probability density function (CPF). In this paper it is argued that this method is not valid because the shape of the CPF is determined by the calibration curve. This hypothesis is tested by a set of null models. An alternative interpretation is given according to which only few episodes of Holocene lake-level changes were climatically driven, while most of the time non-climatic factors were dominating. On a more general level some methodological issues of CPFs are discussed and exemplified by the comparison of dendrochronological results from archaeological settlements and a CPF created using radiocarbon dates from the same settlements. [ABSTRACT FROM PUBLISHER]

Basin water in deep-silled Norwegian fjords is primarily influenced by inflowing Atlantic water originating from the Norwegian Atlantic Current (NwAC). Previous studies suggest that benthic foraminiferal oxygen isotope records from such fjords are strongly influenced by variability in this current. The present paper presents a mid- to late-Holocene record (6–2.2 ka) with 17-yr time resolution from a western Norwegian deep-silled fjord, Voldafjorden. An age model, based on ten AMS radiocarbon dates on marine carbonates and on one plant macrofossil, has been established. The study focuses on the oxygen isotope results, obtained from two species of benthic foraminifera: Cassidulina laevigata and Uvigerina mediterranea. The δ18O C. laevigata record has systematically larger amplitudes than the δ18O U. mediterranea record, which most likely is related to different life cycles/periods of calcification. The oxygen isotope results show a clear shift towards higher values between 5 and 4 ka, interpreted to reflect a temperature drop in the basin water of c. 1°C. After the temperature drop, the high frequency variability (centennial and multidecadal) changes abruptly towards larger amplitudes. This corresponds to changes in subperiodicity, where a 370 year cycle in the δ18O C. laevigata record disappears after 3.8 ka. The δ18O transition corresponds to changes in carbon isotopes and grain size distribution, suggesting that a more extensive change in the fjord environment occurred after the cooling. The timing of the oxygen isotope shift towards higher values and the transition in high frequency variability correspond to major changes recorded in paleoclimate archives within the North Atlantic region and globally. [ABSTRACT FROM AUTHOR]

The late-Holocene deposits of the coastal lowlands bordering the southern North Sea were formed by a renewed expansion of the tidal environment replacing freshwater peats. The sea-level history during the last 2500 years inferred from the post-peat deposits, containing little to no datable organic material, is characterized by two conflicting schools of thought. The first one supports a smooth sea-level curve. The second approach underpins fluctuating sea-level changes. The 'fluctuating' approach also uses facies variations recorded in the post-peat deposits to provide a chronostratigraphical subdivision linked to transgressions and regressions. This paper examines the controlling factors responsible for the facies variations in the post-peat deposits in order to test the approach of the fluctuating sea level. The results of sedimentological investigation coupled with radiocarbon dates of intertidal shells from four shallow outcrops located in nearby sand-filled late- Holocene tidal channels in the Belgian coastal plain are reported. The integration with results from previous work has allowed the reconstruction of the mechanisms and processes of coastal evolution during the late Holocene. The changes in the coastal landscape reflected in the facies variations are caused by multiple factors. The major one is the dynamic nature of the tidal channels responding to changes in accommodation space and sediment budget, and finally, to storm incidence and human impact. The processes of the tidal channel networks, ie, their initiation and evolution, are similar, but the changes happened at different times in different places. The facies variations do not involve rises and falls of sea level, and therefore a fluctuating sea-level rise can not be considered as realistic. [ABSTRACT FROM AUTHOR]

Relative sea-level changes in southwest Britain are poorly constrained because of limitations in the quality and quantity of existing geological data. As a consequence, in contrast to most other regions in the UK, it is not possible to reliably infer rates of land and sea-level change during the last few thousand years. Furthermore, geologically based sea-level reconstructions from this area display significant misfits with relative sea-level predictions based on a recent global model of the glacio-isostatic adjustment process. This paper presents a new record of relative sea-level change for the last 4000 years derived from radiocarbon-dated sea-level index points. In addition to providing information concerning the pattern and rates of late Holocene sea-level change, these data are used to evaluate the suggestion that the apparent misfits between model predictions and geological reconstructions can be satisfactorily explained as a consequence of the lowering of sea-level index points by sediment compaction. The results indicate that a simple, first-order method of decompaction based on the stratigraphic position of sea-level index points, can eliminate much of the misfit between reconstructions and predictions, and substantially reduce vertical scatter in geological data. They also suggest that the influence of compaction on sea-level data from this region may be larger than previously thought. The simple addition of reliable stratigraphic data, in combination with targeted sampling, has the potential to improve our understanding of the compaction process, and increase the utility of existing data. This is increasingly important as the partnership between geophysical modelling and geological investigation becomes more commonplace in sea-level studies around the world. [ABSTRACT FROM AUTHOR]

Long tree-ring chronologies have been constructed in the Northern Hemisphere for dendroclimatology and palaeoenvironmental studies, radiocarbon calibration and archaeological dating. Numerous tree-ring chronologies have also been built in the Southern Hemisphere, primarily for dendroclimatology, but multimillennial chronologies are rare. Development of long chronologies from the Southern Hemisphere is therefore important to provide a long-term perspective on environmental change at local, regional and global scales. This paper describes the extension of the New Zealand Agathis australis (kauri) chronology from AD 911 to 1724 BC. Subfossil (swamp) kauri was collected from 17 swamp sites in the upper North Island. Kauri timbers were also obtained from an early twentieth century house on the University of Auckland campus. Twelve site chronologies and 11 independent tree-sequences were constructed and crossmatched to produce a 3631-yr record, which was calendar dated to 1724 BC–AD 1907 against the modern kauri master chronology. A new long chronology, AGAUc04a, was built by combining the modern kauri data with house timbers and subfossil kauri. This new chronology spans 1724 BC–AD 1998. It is of similar length to chronologies from Tasmania and South America and is the longest tree-ring chronology yet built in New Zealand. The greatest significance of the long kauri chronology lies in its potential as a high–quality palaeoclimate proxy, especially with regard to investigation of the El Niño–Southern Oscillation phenomenon. The chronology also has application to investigation of extreme environmental events, dendroecology, archaeology and radiocarbon calibration. [ABSTRACT FROM AUTHOR]

This paper presents carbon isotope data on soil organic matter (SOM) collected along an ecosystem transect that includes a wooded savannah (cerrado), a tropical semideciduous forest (cerradão), a forest transition type and a tropical forest. The study area is located in the Rondonia state, southwestern Brazilian Amazon region. 14 C data of total soil organic matter and charcoal indicate that the organic matter in these soils is at least Holocene in age. The forest and forest transition sites are characterized by d 13 C soil depth profiles generated typically by C3 plants, indicating no major changes in plant communities have occurred in this region during the time period represented by the isotope data. In contrast, the cerrado and cerradão have experienced significant vegetation changes during the Holocene. The d 13 C data (-30‰ to -27‰) obtained in the deepest part of the profile at the cerradão site show the expansion of the C3 forest vegetation into this region during early Holocene. A vegetation change consisting of increased C4 plant influence is reflected in the 13 C-enriched values (-19‰ to -16.0‰) at both sites during the middle Holocene. The recent part of the 13 C record shows a clear expansion of C3 vegetation, particularly at the cerradão site. The regression/expansion of the forest and savannah vegetation documented at the cerradão and cerrado sites is probably related to changes from a humid to a drier climate and a return to more humid conditions and is in agreement with palaeoclimatic information reported for Brazil and the Bolivian Altiplano. This study suggests that large areas in the Amazon basin have been affected by vegetation changes during the Holocene and that soil organic matter in the transition areas between savannah and forest ecotones contains a valuable palaeorecord of vegetation changes in the Amazon region. [ABSTRACT FROM AUTHOR]