Early Holocene Transition Research Articles

Numerical Reconstruction of Landslide Paleotsunami Using Geological Records in Alpine Lake Aiguebelette

AbstractMass movements and delta collapses are significant sources of tsunamis in lacustrine environments, impacting human societies enormously. Paleotsunamis studies play an essential role in understanding historical events and their consequences, along with their return periods. This study investigates a paleotsunami induced by a subaqueous mass movement during the Younger Dryas to Early Holocene transition, ca. 11,700 years ago in Lake Aiguebelette (NW Alps, France). Utilizing high‐resolution seismic and bathymetric surveys associated with sedimentological, geochemical, and magnetic analyses, we uncovered a paleotsunami triggered by a seismically induced mass transport deposit. Numerical simulations of mass movement have been conducted using a visco‐plastic Herschel‐Bulkley rheological model and corresponding tsunami wave modeled with dispersive and nondispersive models. Our findings reveal for the first time that dispersive effects may be negligible for subaqueous landslides in a relatively small lake. This research reconstructs a previously unreported paleotsunami event and enhances our understanding of tsunami dynamics in lacustrine environments.

Biostratigraphic analysis of a Late Pleistocene to Holocene section from Punta Pescador, eastern Venezuela

A biostratigraphic study was undertaken on a shallow borehole drilled to 90 meters in the easternmost Orinoco Delta, Venezuela. Twenty-eight samples were analyzed for palynomorphs and foraminifera. Palynomorphs were recovered in all except one sample consisting of 178 entities. Foraminifera assemblages of low diversity were recovered in 17 of the 28 samples. The analysis provides some insight into the vegetation, climate, and depositional history allowing comparisons with other Late Pleistocene to Holocene studies in the northern South America region. The Late Pleistocene to Early Holocene transition is marked by an unconformity, where the vegetation changes from a diverse flora of Mauritia flexuosa, grasses (Poaceae), ferns, and mangroves (Rhizophora, Avicennia) to one dominated by Rhizophora around 10,000 years BP. This transition also contains reworked palynomorphs and abundant black wood (inertinite), indicative of erosion and oxidation. The absence of foraminifera suggests an exposed continental shelf and lowering of sea level. The Early Holocene mangrove flora is replaced by vegetation dominated by Mauritia flexuosa, with Symphonia globuliflora, grasses, and ferns. The palynological signature for the upper 42 m of the section compares favorably with a previous study of the Holocene in the Orinoco Delta. Radiocarbon dating indicates there is an unconformity or condensed section at the vegetation change, representing as much as 5500 ± years. Foraminifera indicate an open shelf environment immediately above this horizon followed by a significant shallowing to nearshore transitional environments near the top of the section. Local climate and/or human influence may have been a factor in the abundance of Mauritia flexuosa as suggested by other studies.

The Enmynveem mammoth and vegetation changes in arctic Chukotka during the Late Quaternary

Abstract Mining operations in the Enmynveem valley, northeastern Siberia, exposed a well-preserved right hind leg of Mammuthus primigenius (woolly mammoth), dated to ca. 37,500 cal yr BP. The leg had a fracture that crosscut the midsections of the tibia and fibula. Additional skeletal and soft tissue remains, including two mummified adults (Berezovka, ca. 47,200 cal yr BP; Bolshoi Lyakhovsky, ca. 37,000 cal yr BP), document the presence of mammoths in interior mountain valleys and across both northern and southern coasts of far northeastern Siberia during Marine Isotope Stage (MIS) 3. A mosaic of herb-dominated tundra communities characterized the vegetation of the Enmynveem site during late to middle MIS 3 and MIS 2 (ca. 37,000–17,000 cal yr BP). Shrubs were limited to Salix during the late Pleistocene, whereas Betula also may have been present in sheltered sites during MIS 3. Herb communities remained dominant during the late Pleistocene–Early Holocene transition, although shrub Betula increased during this interval. By ca. 10,200 cal yr BP, the vegetation was Betula–Alnus shrub tundra. Larix and Pinus pumila were established in the valley by ca. 8700 cal yr BP and ca. 5700 cal yr BP, respectively.

Diverse phenotypes of Late Glacial–Early Holocene downy birch (Betula pubescens Erh.) and the morphology of early Preboreal tree stands in southern Schleswig-Holstein

Abstract. The flexibility in growth of Betula pubescens is taken as example for possible erroneous imaginations of Late Glacial–Early Holocene living conditions. The article highlights the factors influencing the phenotype of the contemporary plants, as well as the small-scale patchiness of the distribution of the vegetation in the landscape. The area of investigation is the southern Weichselian younger morainic area of Schleswig-Holstein, including a major Late Glacial archaeological type locality – the Ahrensburg tunnel valley. The period under investigation spans the time between 11 700 and 11 400 cal BP and hence the Late Glacial–Early Holocene transition, which is characterized by a significant shift in the vegetation. This shift has often been seen as a simple transition from treeless tundra to birch forest. The aim of the article is to provide a more realistic image of plant cover of the late Dryas 3 period and the Early Holocene period before the Preboreal oscillation by considering past natural growth limits of Betula pubescens in the study area. The intention is to provide a more accessible interpretation of palaeobotanical data to non-specialists, especially in archaeology.

Late Quaternary glacier advances in the Andes of Santiago, central Chile, and paleoclimatic implications

Andean mountain glaciers in central Chile are in a transitional zone between the seasonal influence of the mid-latitude westerlies and subtropical semiarid conditions to the north. Long-term glacial dynamics for these glaciers and their relationship with the paleoclimate during the late Quaternary are poorly known despite their relevancy. We estimate here the timing and extent of late Pleistocene–early Holocene glaciers in the Andes of Santiago (33°50′S) from geomorphological and geochronological analyses. Our observations evidence that a glacial stage occurred before the Last Glacial Maximum (ELGM) at the San Gabriel drift (1,300 m a.s.l.), dated as ∼46–36 ka. Glacial stages during the latest Pleistocene–early Holocene transition period, partially concomitant with the Antarctic Cold Reversal (ACR) and with the Younger Dryas (YD) chronozones, were identified and dated at La Engorda drift (2,450–2,570 m a.s.l.) at ∼15–10 ka. We propose that the San Gabriel drift represents a prolonged glacial advance driven by increased precipitation and cold conditions off central Chile during glacial times. In La Engorda drift, late glacial advances occurred associated with increased regional precipitation, in the context of a transition from humid to arid climate in central Chile, concomitantly with a general warming trend of sea surface temperatures offshore in the southeastern Pacific and with reduced austral summer insolation. The results support the sensitivity of the Andean mountain glaciers to precipitation and paleoclimate conditions, most possibly associated with periods of increased northward influence of the mid-latitude westerlies during glacial and late glacial times, in addition to the El Niño/Southern Oscillation (ENSO) impact since the mid-Holocene, driving late Quaternary glacier advances in central Chile. We estimate a maximum variation of ∼1,200 m in the position of the late Quaternary Equilibrium Line Altitude (ELA), inferred at ∼3,400 m and ∼3,600 m a.s.l. at the time of the San Gabriel and La Engorda drifts, respectively, with respect to its modern location close to 4,600 m a.s.l.

What burned the forest? Wildfires, climate change and human activity in the Mesolithic – Neolithic transition in SE Iberian Peninsula

Climate variability such as higher or lower temperatures, changing precipitation patterns, shifts in plant communities and other climate-related changes have particularly affected areas with Mediterranean-type climates. A multi-proxy analysis including pollen, sedimentary charcoal, mineralogy and Summed Probability Distributions (SPD) of archaeological 14C dates, allowed the reconstruction of landscape change, geomorphological evolution and fire history at the Laguna de Villena, in the southeastern Iberian Peninsula, during the Mesolithic-Neolithic transition. The Villena paleolake was sensitive to Early Holocene and Middle Holocene regional climatic variability that included several arid phases (around 8.2 ka cal BP, 6.8 ka cal BP and 5.9 ka cal BP) according to geochemical and pollen data. During this period, landscape dynamics show the degradation of oak forests and expansion of pyrophytic pine forests and shrublands, as well as open spaces predominated by grasses. The charcoal record shows a decreasing trend of biomass burned from 8.5 ka cal BP onwards, although fire peaks occurred recurrently during the Early and Middle Holocene. The most intense phase of fire activity was experienced in the last millennia of the Early Holocene, with five fire episodes from 9.1 to 8.4 ka cal BP, coinciding with a phase of higher archaeological evidence in the area. A decrease in archaeological evidence coincides with a gap in fire episodes during the Early Holocene-Middle Holocene transition, suggesting an effect of the abrupt 8.2 ka cal BP event on human activity and on landscape dynamics. After 8.0 ka cal BP, lowerer biomass burned is explained by the configuration of a more open landscape due to the combination of climate (increasing aridity) and increasing human activities in the region. The mineralogical and palynological data highlighted the interaction between human activities, climate and fire dynamics. The sedimentary charcoal record evidenced how most of the fire peaks did not occur in the context of dry episodes, as often assumed, deriving on an anthropogenic explanation related to Early and Late Mesolithic burning practices during a phase of higher archaeological evidence in the Villena paleolake surroundings. Afterwards, combined agropastoral activities from the Early Neolithic onwards and increasing aridity during the Middle Holocene maintained the forest clearances, in the context of fire episodes characterised by decreased biomass burned. This study shows how Middle Holocene palaeoecological records reflect complex histories blending climate and anthropogenic processes that derived in major landscape changes explaining the origin of current landscapes.

Laguna Seca sediments reveal environmental and climate change during the latest Pleistocene and Holocene in Sierra Nevada, southern Iberian Peninsula

Sedimentation in most glacial lakes and wetlands in the Sierra Nevada (southern Iberian Peninsula) began after the last deglaciation and since the Younger Dryas (YD)-Early Holocene (EH) transition. Therefore, until now, studies on older sedimentary records were lacking in this alpine area, which limits the paleoenvironmental and paleoclimatic information to the Holocene. In this study, we studied palynomorphs from the alpine record from Laguna Seca (LS), the longest and oldest (∼18,000 cal yr BP = 18 kyr) sedimentary record in the Sierra Nevada to investigate the response of forests and lake environments in the western Mediterranean area to climate changes and human impact during the latest Pleistocene and Holocene. The deepest lake conditions occurred during the last deglaciation, indicated by the occurrence of Pediastrum algae, which showed highest abundances during the Heinrich Stadial 1 (HS1) and Bølling-Allerød (B-A) transition. Xerophyte herbs such as Artemisia, Ephedra, and Amaranthaceae were highest during the late B-A and YD indicating regional aridity. Poaceae (grasses) were maxima in the B-A and EH, probably indicating expansion in the barren areas after deglaciation. Maximum in temperature and humidity during the EH and cooling and aridification in the Middle (MH) and Late Holocene (LH) are indicated by the changes in the abundance of deciduous Quercus and Pinus forest species. Botryococcus algae increased during the Early Holocene, while the rest of the algae almost vanished, which could indicate that the lake became very productive but shallower until 8.2 kyr. The lake level lowered and became seasonal in the Middle-Late Holocene transition, coinciding with the regional climate aridification. Microcharcoal analysis done on the palynological preparations agrees with the vegetation changes, showing maxima in the EH and MH, related with the maximum in regional forest occurrence, and a decrease in the LH when the Mediterranean vegetation, and thus fuel availability, diminished. This record shows evidence of anthropogenic impact in the last centuries by cultivation, reforestation, cattle grazing, enhanced erosion and eutrophication.

Environmental dynamics of the western European Mediterranean landscape during the Pleistocene to Holocene transition

A strategic aim of research into climate change in the distant past is to respond to the contemporary challenges of global warming at the present. Determining the processes of adaptation by ecosystems to these challenges, evaluating the effects of environmental change on human communities and finding which regions are more or less sensitive to climate change are among the key topics of environmental research today. Throughout the past millennia, some of the most abrupt environmental upheavals were the successive phases of the Late Pleistocene to Early Holocene transition, ranging from cold and dry to mild and damp climates. These phases differed in intensity and effects across all regions of the planet. In this paper, the long-term changes to both vegetation cover and human settlements within the upper Ebro river basin (northern Iberia, western Mediterranean) are shown by new palaeoenvironmental sequences from two archaeological sites dated between ca. 14,000 and 8,000 cal bp, which serve as proxy evidence for past vegetation cover. Summed radiocarbon probability distributions of other nearby archaeological sites were also used to study the dynamics of land occupation throughout the period. The main findings point to vegetation changes changing from the dominance of open landscapes with pines and deciduous woods during the late Pleistocene to the dominance of deciduous forest cover with few areas with open landscapes and far fewer pinewoods during the early Holocene.

New lithic evidence from Terminal Pleistocene-Early Holocene Zhongshan Rockshelter, Guangxi, southern China

The archaeological materials recovered during the 2018 excavation of Zhongshan Rockshelter (ZSRS) in Bubing Basin, Guangxi, southern China helps to fill a cultural gap during the terminal Paleolithic in the region. The evidence from the ZSRS, dated to ∼14,523–8,472 cal. BP, is comparable to other parts of southern China and mainland Southeast Asia where grinding techniques, complex settlement patterns and broad-spectrum subsistence strategies appeared. What distinguishes the ZSRS from other sites in the region however is the widespread use of flaked stone tools and ochre utilization, but with an absence of pottery. This is an excellent example of variation in foraging behavior in this spatio-temporal facies, where one size does not fit all. Regional differences suggest a more complex human foraging strategy rather than a single and fixed behavioral model across southern China during the Terminal Pleistocene to Early Holocene transition.

Ancient DNA Reveals Maternal Philopatry of the Northeast Eurasian Brown Bear (Ursus arctos) Population during the Holocene.

Significant palaeoecological and paleoclimatic changes that took place during Late Pleistocene-Early Holocene transition are considered important factors that led to megafauna extinctions. Unlike many other species, the brown bear (Ursus arctos) has survived this geological time. Despite the fact that several mitochondrial DNA clades of brown bears became extinct at the end of the Pleistocene, this species is still widely distributed in Northeast Eurasia. Here, using the ancient DNA analysis of a brown bear individual that inhabited Northeast Asia in the Middle Holocene (3460 ± 40 years BP) and comparative phylogenetic analysis, we show a significant mitochondrial DNA similarity of the studied specimen with modern brown bears inhabiting Yakutia and Chukotka. In this study, we clearly demonstrate the maternal philopatry of the Northeastern Eurasian U. arctos population during the several thousand years of the Holocene.

Shamanism at the transition from foraging to farming in Southwest Asia: sacra, ritual, and performance at Neolithic WF16 (southern Jordan)

Shamanism is a pervasive form of ritual practice documented within hunter-gathering and farming societies throughout the world, and continuing within some present-day urban communities. Despite exhibiting considerable variation, shamanism has several recurrent features, notably the role of the shaman as a mediator between the spirit and human worlds. Shamanism has been cited to explain aspects of the Epipalaeolithic and Neolithic archaeological records in Southwest Asia and Anatolia. Building on that work, this contribution explores whether shamanism might account for intriguing finds from the early Neolithic settlement of WF16 in southern Jordan, notably a large quantity of bird bones, zoomorphic artefacts and architectural features. A range of interpretations for the evidence are considered with shamanism emerging as the most compelling, suggesting that shamanic thought and practice pervaded daily life at WF16. The paper concludes by proposing that shamanism played a key role in the Early Holocene transition from hunting and gathering to farming in Southwest Asia, as it provided a means for coping with the uncertainty arising from climate and economic change.

Adaptions in subsistence strategy to environment changes across the Younger Dryas - Early Holocene boundary at Körtiktepe, Southeastern Turkey

The site of Körtiktepe in southeastern Turkey is one of few sites in the Upper Mesopotamia basin that attests continuous, permanent occupation across the boundary from end of the colder, drier Younger Dryas (YD) into the comparatively wetter and warmer Early Holocene (EH). This allows for the study of the degree of environmental change experienced on a local level over this boundary as well as for the study of the adaptations that the occupants of the site undertook in response to these changes. The mammal assemblage of Körtiktepe remains relatively stable across the YD – EH transition with the main contributors to diet being mouflon ( Ovis orientalis) and red deer ( Cervus elaphus) in approximately the same quantities, although the contribution of aurochs ( Bos primigenius) increases in the EH. The most significant changes can be seen in the shift in avifauna remains, with a sharp increase of waterbirds during the EH. It is proposed that these shifts reflect changes in the local environment with an increase in woodland cover as well as expansion of local waterways, which is generally consistent with previously published archaeobotanical studies. In terms of species exploited, mortality profiles as well as size distribution of mammals, a great deal of continuity is observed. This suggests that over this particular period the local impact of the beginning of the Early Holocene was not overly dramatic, allowing for cultural continuity of previously established subsistence strategies.

Vegetation response to rapid climate change during the Lateglacial–Early Holocene transition at Gola di Lago, southern Switzerland

Predicting the effects of ongoing climate warming on vegetation requires a long‐term perspective of past ecosystem dynamics. We therefore analysed the sedimentary record from the mire Gola di Lago (985 m a.s.l.) in southern Switzerland, to better understand the vegetation response to past rapid climate change. We present a high‐resolution pollen and plant macrofossil study from the Lateglacial to the Early Holocene (13 400–10 400 cal. a BP), a climatic transition that represents a close analogue to current global warming. The vegetation responses during this time match previously analysed palaeoecological sites south of the Alps. At the end of the Bølling‐Allerød interstadial, the site was surrounded by open larch forest. The beginning of the Younger Dryas was characterized by the local presence and rapid expansion of Pinus cembra, whereas the second part was dominated by Pinus sylvestris, Betula and Larix decidua. These vegetation dynamics agree well with independent climate data indicating a cold and dry start and a subsequent shift to slightly warmer climate. The following rapid temperature increase at the beginning of the Holocene resulted in an increase in forest density and the establishment of novel temperate vegetation assemblages, without major changes in species diversity. Noteworthy, during the Younger Dryas–Early Holocene transition, long‐lived cold‐adapted tree line species such as P. cembra and L. decidua persisted over several centuries, while open boreal forests dominated by P. sylvestris and Betula expanded, indicating high resilience to climatic changes. The results of Gola di Lago suggest that climate warming led to a significant change in vegetation communities through species range shifts. Our study also indicates that some species may potentially be able to locally persist under current global warming, forming novel vegetation assemblages with newly establishing species.

A stable isotope record of late Quaternary hydrologic change in the northwestern Brooks Range, Alaska (eastern Beringia)

ABSTRACTA submillennial‐resolution record of lake water oxygen isotope composition (δ18O) from chironomid head capsules is presented from Burial Lake, northwest Alaska. The record spans the Last Glacial Maximum (LGM; ~20–16k cal a bp) to the present and shows a series of large lake δ18O shifts (~5‰). Relatively low δ18O values occurred during a period covering the LGM, when the lake was a shallow, closed‐basin pond. Higher values characterize deglaciation (~16–11.5k cal a bp) when the lake was still closed but lake levels were higher. A rapid decline between ~11 and 10.5k cal a bp indicates that lake levels rose to overflowing. Lake δ18O values are interpreted to reflect the combined effects of changes in lake hydrology, growing season temperature and meteoric source water as well as large‐scale environmental changes impacting this site, including opening of the Bering Strait and shifts in atmospheric circulation patterns related to ice‐sheet dynamics. The results indicate significant shifts in precipitation minus evaporation across the late Pleistocene to early Holocene transition, which are consistent with temporal patterns of vegetation change and paludification. This study provides new perspectives on the paleohydrology of eastern Beringia concomitant with human migration and major turnover in megafaunal assemblages.

The spatio-temporal structure of the Lateglacial to early Holocene transition reconstructed from the pollen record of Lake Suigetsu and its precise correlation with other key global archives: Implications for palaeoclimatology and archaeology

Abstract Leads, lags, or synchronies in climatic events among different regions are key to understanding mechanisms of climate change, as they provide insights into the causal linkages among components of the climate system. The well-studied transition from the Lateglacial to early Holocene (ca. 16–10 ka) contains several abrupt climatic shifts, making this period ideal for assessing the spatio-temporal structure of climate change. However, comparisons of timings of past climatic events among regions often remain hypothetical because site-specific age scales are not necessarily synchronised to each other. Here we present new pollen data (n = 510) and mean annual temperature reconstruction from the annually laminated sediments of Lake Suigetsu, Japan. Suigetsu's 14C dataset is an integral component of the IntCal20 radiocarbon calibration model, in which the absolute age scale is established to the highest standard. Its exceptionally high-precision chronology, along with recent advances in cosmogenic isotope studies of ice cores, enables temporally coherent comparisons among Suigetsu, Greenland, and other key proxy records across regions. We show that the onsets of the Lateglacial cold reversal (equivalent to GS-1/Younger Dryas) and the Holocene were synchronous between East Asia and the North Atlantic, whereas the Lateglacial interstadial (equivalent to GI-1/Bolling-Allerod) started ca. two centuries earlier in East Asia than in the North Atlantic. Bimodal migration (or ‘jump’) of the westerly jet between north and south of the Tibetan plateau and Himalayas may have operated as a threshold system responsible for the abruptness of the change in East and South (and possibly also West) Asia. That threshold in Asia and another major threshold in the North Atlantic, associated with switching on/off of the Atlantic meridional overturning circulation (AMOC), were crossed at different times, producing a multi-centennial asynchrony of abrupt changes, as well as a disparity of climatic modes among regions during the transitional phases. Such disparity may have disturbed zonal circulation and generated unstable climate during transitions. The intervening periods with stable climate, on the other hand, coincided with the beginnings of sedentary life and agriculture, implying that these new lifestyles and technologies were not rational unless climate was stable and thus, to a certain extent, predictable.

A multi-proxy reconstruction of climate during the late-Pleistocene to early Holocene transition in the northeastern, USA

AbstractA multiproxy record from Twin Ponds, VT, is used to reconstruct climatic variability during the late Pleistocene to early Holocene transition. Pollen, ostracodes, δ18O, and lithologic records from 13.5 to 9.0 cal ka BP are presented. Pollen- and ostracode-inferred climatic reconstructions are based on individual species’ environmental preferences and the modern analog technique. Principal components analysis of all proxies highlights the overall warming trend and centennial-scale climatic variability. During the Younger Dryas cooling event (YD), multiple proxies show evidence for cold winter conditions and increasing seasonality after 12.5 cal ka BP. The early Holocene shows an initial phase of rapid warming with a brief cold interval at 11.5 cal ka BP, followed by a more gradual warming; a cool, wet period from 11.2 to 10.8 cal ka BP; and cool, dry conditions from 10.8 to 10.2 cal ka BP. The record ends with steady warming and increasing moisture. Post-YD climatic variability has been observed at other sites in the northeastern United States and points to continued instability in the North Atlantic during the final phases of deglaciation.

New insights into Late Devensian Lateglacial and early Holocene environmental change: Two high-resolution case studies from SE England

The Late Devensian Lateglacial to early Holocene transition across north-west Europe was characterized by a rapid shift in climate from the cold, harsh conditions of the Loch Lomond Stadial to the warmer climate of the early Postglacial. However, our knowledge of this transition in south-east England has been hampered by the paucity of mires with sedimentary records spanning this period. We present two new high-resolution paleoenvironmental records from Langshot Bog and Elstead Bog B (Surrey, UK), which provide a clear signature of vegetation succession and fire history. Organic sedimentation at Langshot Bog commenced prior to 12,640–12,410 cal. BP (95% probability) and continued until 8430–8350 cal. BP (95% probability). Providing a robust chronology for Elstead Bog B proved to be problematic, although available dates suggest sediment accumulation commenced prior to 11,820–11,400 cal. BP (WM-168, 2σ). The sites are characterized by similar vegetation records, indicating a regional signal from locations over 20 km apart. Scrubby tundra-style vegetation is characteristic of cold conditions associated with the Lateglacial. The identification of Alnus and Corylus, taxa not normally associated with this period, indicates that microclimates may have permitted the survival of these species. Expansion of Betula followed by Pinus dates to the onset of the Holocene, forming mixed coniferous-deciduous woodland, during a period which is punctuated by short climatic events identified from stable isotope analysis. Subsequent expansion of thermophilous taxa Corylus, Ulmus and Quercus results in the formation of deciduous woodland. A rise in micro-charcoal, heathland and herbaceous taxa indicates development of heathy-scrubby clearings within this Holocene landscape.

Environment and human subsistence in Northern France at the Late Glacial to early Holocene transition

The Late Glacial and early Holocene (ca. 15,000–6,000 cal BP) witnessed major changes in the environmental conditions which led to the establishment of temperate vegetation and animal species, thereby offering new subsistence opportunities to the population of hunter-gatherers. Measurements of the relative abundances in 13C and 15N were applied to large herbivores from northern France to document the change in their habitat. During the early Holocene, red deer show a decrease in δ13C values most likely reflecting the effect of a dense canopy and an increase in δ15N values probably linked to the increased soil activity of soils in foraged territories. Aurochs and roe deer δ13C values also revealed a more densely forested habitat at the end of the Preboreal, while the δ13C values of the wild boar indicate dependence on fruits and underground tubers that were not affected by the canopy effect. Three human individuals from Val-de-Reuil and La Chaussée-Tirancourt dated to the Preboreal period provided relatively high δ15N values when compared with the local fauna and other early Mesolithic humans, which might have resulted from the consumption of freshwater resources especially at Val-de-Reuil. The δ34S values appear to depend more on the geographical location of the individual, as demonstrated by the difference among wild boar δ34S values between sites, rather than related to the protein source of the diet, namely, terrestrial versus aquatic. Our results confirm the influence of the forest ecosystem on the environment and diet of the considered early Mesolithic human of northern France, while the possible contribution of the aquatic ecosystem still needs to be documented.

An updated radiocarbon dataset of late Pleistocene to Holocene archaeological sites in the Cubilán area, southern highland Ecuador

Thirty-two radiocarbon dates obtained from four archaeological sites in the southern Andean Range of Ecuador are presented in order to contribute toward filling existing chronological and interpretive gaps regarding human occupations in highland South America, mainly during the late Pleistocene to early Holocene transition. These radiocarbon dates, together with nine other dates previously obtained for the studied area, were submitted to significance tests analyses to assess which of them are statistically similar at the intra- and inter-site scales. Pooled mean ages and respective clusters of dates were combined with isolated dates of studied sites, and with artifactual data aiming at producing some initial interpretations regarding micro-regional human dynamics for southern highland Ecuador through time. In the studied area of ~55 km2 diverse anthropogenic scenarios directly linked with proposed chronological stages are briefly described. These activities suggest that local and micro-regional human interaction dynamics were consistent, continuous, and complex through time from 12,000 cal. BP onward.

Reconstructing organic matter sources and rain rates in the southern West Pacific Warm Pool during the transition from the deglaciation period to early Holocene

Transient features in the organic carbon content of deep-sea sediment cores resulting from changes in the flux and/or quality of sedimentary organic matter are not uncommon. We examined the geochemical characteristics of sediments retrieved with a gravity corer from the northwestern Solomon Sea (3908 m water depth), southern West Pacific Warm Pool (WPWP). δ13C and δ15N of sedimentary organic matter, together with TOC/TN data suggest that the organic material is characterized by a mixture of marine and terrestrial origins with a higher contribution from marine algae. The data were analyzed with an inverse non-steady-state reaction-transport model to examine the variability and magnitude of particulate organic carbon (POC) flux to the seafloor during the transition between the deglaciation period and early Holocene. Measured POC content and porewater NO3−, NH4+, DIC and SO42− concentrations were used to constrain the model. Hindcast results revealed that POC flux decreased from 75 to 37.5 μg cm−2 yr−1 during the deglaciation–early Holocene transition. The rate of POC degradation in the present setting is slightly lower compared to that in the pre-Holocene setting. The synchronous decline in the relative contribution of terrestrial organic matter input and rapid sea level rise during this transition suggest that sea level, rather than surface productivity, is the dominant factor controlling the POC deposition flux in the Solomon Sea. This is conceivable because the sampling site is proximal to high-relief islands with high rainfall, a well-developed submarine canyon system and narrow and steep continental margins. Consequently, we suggest that deep-water basins in proximity to similar high-relief mountainous islands in the tropical Pacific may represent important sinks for terrestrial organic material, especially during sea level lowstands.