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In 2013 archaeological radiocarbon databases covering 13,000–7000 14C BP for nine countries in South America, including Peru, were published in a special issue of Quaternary International. The past decade has seen new field research and radiocarbon ages contributed to the Peruvian archaeological record, two updates to the southern hemisphere calibration curve, and research papers drawing from South American radiocarbon databases to explore region- and continent-scale patterns of human-environment interaction, settlement dynamics, and paleodemography. This paper provides an update to the Peruvian archaeological radiocarbon database for the Late Pleistocene to early Middle Holocene. The new database (version 2) includes 493 radiocarbon dates spanning 20,000 to 7000 14C BP. No radiocarbon dates >13,000 14C BP meet basic archaeological criteria. First, I review the structure of Peru's early archaeological radiocarbon record and highlight several research and landscape taphonomic biases. Second, I examine distributions of archaeological sites through time, beginning with basic site and date frequencies and progressing to Bayesian analysis of aggregated radiocarbon dates. Third, applying established criteria for well-dated archaeological events, I identify some unresolved problems in early Peruvian radiocarbon chronologies, with the goal of outlining priorities for future archaeological and chronometric research. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The late Quaternary is a key stratigraphic interval as it encompasses the Late Glacial to Holocene transition, which is characterized by a series of pronounced centennial climate oscillations and subsequent short-term events of paleoceanographic variability. Across this stratigraphic interval, significant turnovers and faunal changes in the composition and abundance of planktonic foraminiferal assemblages are well-documented through their high-resolution quantitative analysis performed in the south Aegean core NS-18. The identification of 10 synchronous bioevents among the Mediterranean sub-basins allows accurate inter-basinal correlations over the study time interval, thus contributing to the development of a robust chronostratigraphic framework for this setting. Moreover, the identification and timing of additional 20 diachronous bioevents, in conjunction with the already established bio-ecozonation scheme of the Aegean Sea, provide a continuous record of faunal changes (in terms of species-specific distributional abundances) which can be used as an additional locally expressed biochronological tool for the eastern Mediterranean deep-sea cores. The present study certainly indicates that the cause-and-effect relationships between the paleoceanographic/paleoclimatic perturbations and biological response require a highly resolved regional chronostratigraphy. [ABSTRACT FROM AUTHOR]

The aims of this work are to characterize the paleoenvironmental evolution and the sedimentary fluvial responses to climate and river flow changes of the upstream reaches of the Sado estuary since the Mid-Late Holocene. By combining the previous information, we also intent to define the limit of the fluvial-estuarine boundary and maximum limit of tidal influence of the estuarine area during the last 4500 years. To accomplish these objectives a 10.5 m-long sediment core was collected at ca. 65 km upstream the Sado estuary inlet and studied using multiproxy analyses and radiocarbon dating. In addition, multi-proxy data from sediment cores and superficial samples collected downstream, in the alluvial plain and intertidal areas near the present-day fluvial-estuarine boundary, were combined and contributed to the interpretations. We concluded that: i) the organic matter is mostly sourced in terrestrial/freshwater environments even during periods with marine influence, as suggested by the occurrence of marine benthic diatoms between 4300 and 4200 cal BP; ii) the fluvial-estuarine boundary retreat during the Middle to Late Holocene transition (4350-4000 cal BP) reaching areas of the Sado river (Laxique), located ca. 15 km upstream of the present-day boundary; iii) modifications on the location of the fluvial-estuarine boundary are mostly derived from drier climatic conditions and consequent flow river discharges; iv) the aggradation and progradation of the alluvial plain started at ca. 4000 cal BP at Laxique (and at ca. 3240 cal BP at Arapouco); and v) the abrupt change in the sedimentation rates and sedimentation pattern before and after the beginning of the alluvial plain aggradation process (4000 cal BP at Laxique and 3240 cal BP at Arapouco) reflects essentially changes in the fluvial activity and the loss of accomodation space. [ABSTRACT FROM AUTHOR]

The nature of the mechanisms that have shaped the animal communities of the island of Ireland remains a pervasive question in the study of the Quaternary of north-western Europe. Archived Quaternary faunal bone assemblages from antiquarian excavations of cave sites are a direct line of evidence with demonstrable potential to shed light on this issue, but are currently constrained by limited publication, understanding of early excavation protocols, and a lack of chronological reference. Alice and Gwendoline Cave in the west of Ireland was the subject of extensive excavations in 1902, which yielded a substantial faunal assemblage and the first evidence of an Upper Palaeolithic human presence on the island during the terminal Pleistocene. Here, we report further results from this important site. Archaeological excavations and a radiocarbon dating programme in 2019-2020 have shed light on the environmental context of the faunal assemblage, the cave taphonomy and site chronology. Nineteen radiocarbon dates are now available, including new direct dates for brown bear (Ursus arctos), giant deer (Megaloceros giganteus) and reindeer (Rangifer tarandus). The archaeological excavations and the analysis of sedimentary lipids – the first of its kind for an Irish cave site, both suggest that the sediments are primarily of exogenous origin, likely carried into the cave through fissures and openings by runoff or colluvial movements. Our analyses indicate that there were at least three main 'pulses' of bone-bearing sediment accumulation: at the beginning of the Younger Dryas (c. 12,700 cal. BP), in the aftermath of the Younger Dryas (11,300 cal. BP) and in the Early Holocene (c. 10,000 cal. BP), with a hiatus in sediment deposition after 9700 cal. BP. • New direct dates for brown bear, giant deer and reindeer • Persistence of brown bear, giant deer and reindeer during first centuries of Younger Dryas • First instance of sedimentary lipid analysis of Irish cave deposits • Re-evaluation of the site with first evidence of Pleistocene human occupation of Ireland [ABSTRACT FROM AUTHOR]

The aim of this work is to examine the rodent exploitation strategies employed by the human groups that occupied the Dry Puna of Argentina during the Early and Mid-Holocene. We analyze the characteristics of the archaeological bone assemblages and present stable isotope compositions of Chinchillidae remains recovered in two Puna sites dated between 10,600–5200 years BP. Since rodent population dynamics and diets are largely reliant on local resources given their reduced spatial range, these results provide new valuable information to explore local environmental conditions in the past and how these influenced the rodent exploitation strategies employed by the hunter-gatherers that inhabited this area during the Early-Mid Holocene transition. Thus, this work presents detailed zooarchaeological data as well as δ 13C VPDB and δ 15N AIR values measured on bone collagen extracted from Lagidium sp. and other chinchillid remains recovered at Hornillos 2 and Inca Cueva 4, two archaeological sites dating to this period. These results are compared with the δ 13C VPDB and δ 15N AIR values measured on modern plants collected in the vicinity of both sites to address rodent dietary change through time as well as human procurement strategies. Our results show certain continuities for the Early-Mid Holocene transition, underlining the importance of areas such as Inca Cueva and Hornillos for past human groups, given the consistent availability of key resources for subsistence. • Past rodent exploitation strategies are studied in the Dry Puna of Argentina. • Chinchillids were an important resource during the early and mid-Holocene. • Zooarchaeology and stable isotope analysis are combined to achieve new results. • Results show continuities between early and mid-Holocene human occupations. • The areas studied were used as refugia within a changing environment. [ABSTRACT FROM AUTHOR]

The emergence of Neolithic economies and their spread through Eurasia was one of the most crucial transitions of the Holocene, with different mechanisms of diffusion—demic, cultural—being proposed. While this phenomenon has been exhaustively studied in Europe, with repeated attempts to model the speed of Neolithic diffusion based on radiocarbon dates, much less attention has been devoted to the dispersal towards the East, and in particular to South Asia. The Neolithic in the latter region at least partly derived from southwest Asia, given the presence of "founder crops" such as wheat and barley. The process of their eastward diffusion, however, may have been significantly different to the westward dispersal, which was mainly due to demic diffusion, as local domesticates were already available and farming was already practiced in parts of South Asia. Here, we use radiocarbon dates specifically related to the spread of the southwest Asian Neolithic crops to model the speed of dispersal of this agricultural package towards South Asia. To assess potential geographical and environmental effects on the dispersal, we simulate different speeds depending on the biomes being crossed, employing a genetic algorithm to search for the values that most closely approach the radiocarbon dates. We find that the most important barrier to be crossed were the Zagros mountains, where the speed was lowest, possibly due to topography and climate. A large portion of the study area is dominated by deserts and shrublands, where the speed of advance, albeit closer to the range expected for demic diffusion, was lower than observed in Europe, which can also potentially be attributed to environmental constraints in the adaptation of the crops. Finally, a notable acceleration begins in the Indus valley, exceeding the range of demic diffusion in the tropical and subtropical environments east of the Indus. We propose that the latter is due to the rapid diffusion among populations already familiar with plant cultivation. [ABSTRACT FROM AUTHOR]

The study of the settlement of the Central European Plain during the Late Glacial time has until recently been hampered by the predominance of the view that large glacial lakes were widespread in the upper Volga basin during the Valdai (Weichselian) glaciation, which prevented settlement of vast territories and population migration to the ice-free Fennoscandia from the east and south-east. According to the glacial lake concept, the lowlands along the Dubna River – a tributary of the Volga River – were occupied by the vast Tver Lake in the Late Valdai epoch, the presence of which was previously thought to exclude the possibility of its development until the Pleistocene-Holocene boundary, when the process of deglaciation finally drained those areas. To test this concept, special geoarchaeological studies were undertaken, which included, in addition to traditional archaeological research, the study of the development history of landscapes by methods of geology and geomorphology. It was established that fluvial rather than lacustrine environments dominated the area during the Late Valdai Ice Age, which made possible its occupation by prehistoric population. In support of that, radiocarbon ages of around 15,500 cal BP were obtained from the artifacts corresponding the initial settlement of the Dubna Lowland. The pioneers were populations of the Resseta culture with the East Gravettian traditions. Later, in the Early Holocene, there is a transformation of the Ressetian industry into the Zadnepilevo culture. Seasonal migrations of the Ressetian and Zadnepilevian population are recorded not only by materials of the East European Plain, but also the Scandinavian Peninsula, where the monuments of "eastern impulse" are represented. [ABSTRACT FROM AUTHOR]

We have received unique material on the development of the natural environment for the last 12 400 cal. yr. BP in the central part of Iturup Island. High-resolution paleoreconstructions have been based on the multi-proxy study of paleolake sediments found on the plateau (height 400–420 m) located northwest of the Baransky Volcano. For the first time, a record of paleogeographic events has been obtained for the Late Glacial and the Early Holocene. The age model is based on nine radiocarbon dates. Diatom analysis has made it possible to distinguish 11 stages of lake–swamp evolution. The paleolake reached its maximum depth at ~9890–7900 cal. yr. BP and became extinct at 1400 cal. yr. BP. The vegetation development stages and the landscape change factors have been restored. The Younger Dryas cooling recorded in Iturup was characterized by humidity changes. The role of forest vegetation rapidly increased at the Pleistocene–Holocene boundary of ~11 470 cal. yr. BP under warmer climatic conditions. Distribution of dwarf pine as an indicator of stable snow cover has been analyzed. Dark-coniferous forests existed in the mountainous part of the island since the Late Glacial and were the most widespread in the Early Holocene. The onset of birch forest expansion at 6200 cal. yr. BP was related to the intensification of volcanic activity and frequent ash falls. A number of identified cold events were enhanced by the weakening of the warm Soya Current. The intensive transfer of allochthonous pollen from the southern Kuril Islands and the Japanese Islands at 3540 cal. yr. BP is a sign of cyclogenesis intensification in the Kuril Islands. The Holocene climatic rhythms in the landscape development of the Iturup mountains, as well as the influence of warm and cold currents and other regional factors, have been analyzed. [ABSTRACT FROM AUTHOR]

A number of AMS radiocarbon dates, accumulated since the 1990's, reveal that ceramic technology first developed among non-agricultural, hunter-gatherer societies in the late Pleistocene of East Asia. Specifically, on the Japanese Archipelago the radiocarbon chronology indicates a diverse trajectory of pottery adoption. The earliest adoption of pottery here was by mobile hunter-gatherers, regardless of region and climatic event. On the other hand, pottery culture suddenly started to flourish later along the warmer Pacific coastline region of southwestern Japan just after the onset of climatic warming of the Late Glacial, and spread throughout the archipelago by the onset of the Holocene. Climatic amelioration, therefore, did not induce the 'beginning' of pottery use, but prompted the 'development' of sedentary lifestyles accompanying intensified use of pottery. This complicated situation clearly means that motivation and context of pottery adoption do not follow a simple explanation. However, recent studies of chemical and isotope analyses of charred residues on pottery indicate similar use of early pottery throughout the archipelago in the late Pleistocene and the early Holocene. This paper critically re-evaluates these issues through examining synchronic and diachronic archaeological contexts. Existing data indicate that there is great inter-regional variability in technology, subsistence, paleoenvironment, and adaptation associated with pottery, therefore the motivation for the adoption of pottery is distinct within various geographical, environmental, and temporal contexts in the archipelago. [ABSTRACT FROM AUTHOR]

Amazonia constitutes one of the most ethnically diverse regions in the world. However, our understanding of the arrival and historical trajectories of people in Amazonia is still poorly understood. Our recent excavations in the Serranía de la Lindosa have begun to fill this gap and provide new insights into the first human societies that settled in the Colombian Amazon region during the Younger Dryas (YD) period of the late Pleistocene. This paper details the stratigraphy, taphonomy and chronological framework of two rock shelters, Cerro Montoya 1 and Limoncillos, from excavations carried out by the LASTOURNEY project between 2021 and 2022. Based on radiocarbon dates from five multicomponent sites (Cerro Azul, Cerro Montoya 1, Limoncillos, Angosturas II and Casita de Piedra), four distinct phases of occupation are modelled using OxCal program (v.4.4). late Pleistocene-early Holocene (12.6–10. 0 cal ka BP); early to middle Holocene (9.5–5. 9 cal ka BP); initial late Holocene (4.1–3. 7 cal ka BP), and late Holocene (3.0–0. 3 cal ka BP). We establish the arrival date of the first human groups to the Colombia Amazon by ∼12. 6 cal ka BP , who settled in a tropical rainforest environment, practised a generalised subsistence, had an expedient unifacial technology, and began to paint with ochre on the walls of the mesa-top tepuis by at least ∼10. 2 cal ka BP. The chronology indicates gaps in the sequence during the middle Holocene, between 5.9–4. 1 cal ka BP , likely representing periods of abandonment. • We report several new evidences of early peopling of Amazonia River basin. • We report new evidences of human occupations of the Serranía La Lindosa (Colombian Amazon). • We report the data of two rock shelters, Cerro Montoya 1 and Limoncillos. • We report several lines of evidence on the human adaptability to the Colombian Amazon lowlands. • The humans who settled in the Serrania La Lindosa "humanized" the territory by rock art. [ABSTRACT FROM AUTHOR]

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. • Radiocarbon data from six archaeological sites indicate repeated visits to a region of about 3,000 masl in southern Ecuador from the late Pleistocene into the late Holocene. • The focus of activities over the course of nearly 10,000 years in the Cubilán area was on the procurement of lithic materials and the manufacture of stone tools. • Significant tests of large radiocarbon datasets from sites in a single region allow the identification of the timing and intensity of regional occupations not otherwise determinable. [ABSTRACT FROM AUTHOR]

Grassland ecosystems are some of the most modified ecosystems in the world, largely due to conversion to cropland, and the High Plains of the central United States is no exception. Playa wetlands are ubiquitous features of the High Plains and have experienced increased sediment accumulation, which is the primary cause of reduced playa ecosystem function. Seven playas on the High Plains of western Kansas, five with cropland-dominated watersheds and two with grassland-dominated watersheds, were examined to quantify the amount of recent (past ~100–175 yr) sediment accumulated within playas and to establish chronologies of playa filling. Thicknesses of recent sediment were determined in the field, and soil cores were extracted from study playas. Four playa cores were analyzed for 210Pb to establish the chronology of recent sediment accumulation and sedimentation rates. Chronologies of pre-agricultural sediments and sedimentation rates were calculated by 14C dating of buried soils preserved within playa cores. Radiocarbon ages indicate playa stratigraphic records span the Holocene and that these playas have persisted on the landscape since at least the Late Pleistocene. Long-term, natural sedimentation rates were highest during the Pleistocene-Holocene transition and early Holocene, at ~2–4 cm/century. During the middle and late Holocene, sedimentation rates averaged ~1 cm/century. Cropland playas accumulated ~10–15 cm of recent sediment at average rates of ~6.5–10 cm/century, while grassland playas accumulated only ~2 cm of recent sediment. Conversion of watersheds to cropland has greatly accelerated sediment accumulation within playas, which is generally resulting in a decline in critical playa ecosystem functions. • Long-term playa sedimentation rates ranged from ~1–4 cm/century throughout the Holocene. • Cropland playas accumulate sediment 2–10 times faster than long-term sedimentation rates. • Grassland playas accumulate sediment approximately equal to long-term sedimentation rates. • 210Pb chronologies indicate recent sediment thickness can reliably be determined visually. [ABSTRACT FROM AUTHOR]

The late Pleistocene-early Holocene archaeological record of the interior Pacific Northwest is dominated by what has been regionally referred to as the Western Stemmed Tradition (WST). While various efforts have attempted to clarify the chronology of this tradition, these have largely focused on data from the Great Basin and have been disproportionately preoccupied with establishing the beginning of the tradition due to its temporal overlap with Clovis materials. Specifically focusing on the Columbia Plateau, we apply a series of Bayesian chronological models to create concise estimates of the most likely beginning, end, and span of the WST.We then further explore its chronology by modeling its temporal span under various parameters and criteria so as to better identify places in the chronology that need further work and those that are robust regardless of data iteration. Our analysis revealed four major findings: (1) WST conservatively dates between 13,000 and 11,000 cal BP, likely extending to ~13,500 cal BP; (2) the most problematic period for WST is its termination; (3) the WST is incredibly long-lived compared to roughly contemporary Paleoindian traditions; and (4) the WST was seemingly unaffected by the onset of the Younger Dryas. [ABSTRACT FROM AUTHOR]

Very few excavated sequences in southern South America provide an approximation to the environmental evolution covering the segment Late Pleistocene-Holocene. Here we present the taphonomic analysis and paleoenvironmental reconstruction based on the small mammal remains retrieved from the archaeological and paleontological site Gruta del Indio (Mendoza Province, Argentina). Radiocarbon dates situate the small mammal deposits studied within the Late Pleistocene and Holocene. Thus, these assemblages provide a record for inferring environmental evolution in the middle basin of Atuel River during the last ∼31 ky BP. Taphonomic analysis revealed that most of small mammal remains were incorporated by a little destructive nocturnal owl. Recorded species include mainly cricetid and caviomorph rodents and a single marsupial. While Pleistocene assemblages have not exclusive species, the specific richness increases towards the Holocene probably linked with the climatic variability related to ENSO. In overall, the recorded small mammals suggest environmental stability during the Late Pleistocene-Holocene, mostly associated with Monte Desert conditions. Conversely, the pollen sequence studied from Gruta del Indio was interpreted as indicator of a deep environmental change during the Pleistocene-Holocene transition, when the Patagonian steppe was replaced by Monte Desert. Potential biases linked with these kinds of proxies are discussed. [ABSTRACT FROM AUTHOR]

This work presents data on charcoal fragments found in Cenozoic deposits of the Boa Vista Formation and the first absolute dating for this unit. The methodology consisted of the definition of sedimentary facies, as well as the establishment of depositional age using optically stimulated luminescence (OSL) in quartz grains. Analysis was carried on charcoal samples with the help of Scanning Electron Microscopy (SEM), AMS 14C dating, and organic petrography. The facies analysis identified four distinct facies: lateritic massive gravel facies (Gcm1), ferruginous massive gravel facies (Gcm2), massive sand facies (Sm) and fossiliferous massive sand (Smf). The ages of the deposits ranged between 105,2 and 3,2 thousand years before present, indicating that this unit is positioned in the Upper Pleistocene-Upper Holocene transition. The anatomical structures observed in SEM are well preserved and the studied charcoal samples have angiospermic affinity. Two episodes of fires were identified with range ages between 5663 and 3377 cal years BP, with burning temperature varying from 340 °C to 400 °C. • OSL dating for the Cenozoic portion recorded a Pleistocene - Holocene age. • Fire episodes have been identified for the Middle Holocene of northwestern Brazil. • These fire episodes corroborate data recorded for other regions of the Amazon. [ABSTRACT FROM AUTHOR]

The magnetic susceptibility (MS) of Chinese loess deposits is extensively used to reconstruct climate changes from centennial to earth orbital time scales. The approach assumes that the MS is sensitive to the variations of the Asian Summer Monsoon (ASM), and thus that changes in MS are synchronous across the Chinese Loess Plateau. However, this inference has not been fully confirmed due to the limitations of both chronological control of Chinese loess sequences and the climatic proxies of the ASM. Here, we present the results of radiocarbon dating of the shifts in the oxygen isotopic composition of fossil land snail shells (δ 18 O s ) and in MS during the Pleistocene/Holocene transition at various sites in Chinese Loess Plateau. The results show that the age of shift in MS at Pleistocene/Holocene transition at Mangshan, Heshui, and Huanxian sections is 10.43 ka, 8.55 ka, and 7.13 ka BP, respectively. Thus, the shift is time-transgressive with age decreasing from southeast to northwest across the plateau. However, the δ 18 O s record, which is directly related to the precipitation delivered by the ASM, is not significantly time-transgressive, indicating that the ASM strengthened almost simultaneously across the plateau. We suggest that the time-transgressive nature of the shifts in MS may result from the low amplitude of the ASM strengthening during the Pleistocene/Holocene transition. Overall, our results demonstrate a regional difference in the insensitivity of MS to low amplitude climatic changes, and they challenge the previously-held assumption that the ages of climatic boundary based on MS stratigraphy are time-equivalent in Chinese loess. [ABSTRACT FROM AUTHOR]

Goda Buticha is a cave site near Dire Dawa in southeastern Ethiopia that contains an archaeological sequence sampling the late Pleistocene and Holocene of the region. The sedimentary sequence displays complex cultural, chronological and sedimentological histories that seem incongruent with one another. A first set of radiocarbon ages suggested a long sedimentological gap from the end of Marine Isotopic Stage (MIS) 3 to the mid-Holocene. Macroscopic observations suggest that the main sedimentological change does not coincide with the chronostratigraphic hiatus. The cultural sequence shows technological continuity with a late persistence of artifacts that are usually attributed to the Middle Stone Age into the younger parts of the stratigraphic sequence, yet become increasingly associated with lithic artifacts typically related to the Later Stone Age. While not a unique case, this combination of features is unusual in the Horn of Africa. In order to evaluate the possible implications of these observations, sedimentological analyses combined with optically stimulated luminescence (OSL) were conducted. The OSL data now extend the radiocarbon chronology up to 63 ± 7 ka; they also confirm the existence of the chronological gap between 24.8 ± 2.6 ka and 7.5 ± 0.3 ka. The sedimentological analyses suggest that the origin and mode of deposition were largely similar throughout the whole sequence, although the anthropic and faunal activities increased in the younger levels. Regional climatic records are used to support the sedimentological observations and interpretations. We discuss the implications of the sedimentological and dating analyses for understanding cultural processes in the region. [ABSTRACT FROM AUTHOR]

The drainage integration of three Late Pleistocene intramontane basins located in the southern Italian Apennines was reconstructed by integrating information derived from geomorphic, structural, and stratigraphic analyses. The Santaloja (SLJ), Lago (LG), and Pantani (PN) basins are located in the axial zone of the Apennines fold-and-thrust belt where they mainly comprise Mesozoic to Cenozoic deep-sea water siliceous and calcareous rocks. The Quaternary development of these intramontane basins draining the Basento River catchment provides an example of drainage evolution within collisional mountain belts and its tectonic and climatic controlling mechanisms. Tectonically, sets of NW-SE- and NE-SW-trending faults formed a large trough with ensuing river valley development configured to synclinal folds. The ongoing interplay of these active and passive tectonic controls lead to compartmentalisation into three endorheic basins. Uncalibrated radiocarbon dating of peat layers from boreholes reveals that lacustrine facies conditions prevailed during the Late Pleistocene, spanning 34,785 to 41,325 ka during Marine Isotope Stage 3. Morphometric analysis suggests that these endorheic lacustrine basins subsequently became integrated via overspill from 13.25 kyr calBC onwards linked to Late Pleistocene climatic changes creating the Basento River. Within the axial zone of the southern Apennines, tectonically driven headwards erosion is commonly attributed to lengthening of major rivers like the Basento River. However, this study demonstrates a more complex interplay between tectonics and climate change for intramontane basin development and its drainage evolution. • Late Pleistocene drainage integration of intramontane basins in southern Italy was investigated. • We applied a multidisciplinary approach and radiocarbon dating of lacustrine clay. • Tectonics and climate change have controlled the basins development and the drainage evolution. • Endorheic basins became integrated via overspill mechanism starting from 13.25 kyr calBC. • Drainage integration process was responsible for the downstream lengthening of the Basento River. [ABSTRACT FROM AUTHOR]

The settlement of Patagonia has been the subject of extensive research, although key questions about the timing of arrival of the first humans and the subsequent patterns of dispersal and demographic changes within the region remain largely unresolved. In this study we evaluated the most probable date for the initial peopling of Patagonia and explored the temporal and spatial changes in population size along Late Pleistocene–Holocene by using robust statistical methods for the analysis of radiocarbon dates and molecular data. We suggest that the first humans probably arrived to Patagonia around 17,000–14,000 years BP, a few thousands of years earlier than generally stated. Within the region, the populations experienced a sustained and slow growth until the transition Pleistocene–Holocene, when the population size started to increase, with a remarkable acceleration after 7000–5000 years BP and reaching its maximum at 1000 years BP. The spatial occupation was not homogeneous across the region though, changing from a more intense continental occupation to a coastal occupation in the Late Holocene. This pattern of peopling and population expansion, obtained here on the basis of a rigorous and comprehensive quantitative approach, will allow the future evaluation of formal models about the ecological and cultural processes that drove the evolution of the human populations from Patagonia. [ABSTRACT FROM AUTHOR]

This paper presents a synthesis on the existing of the role of plants on the adaptive strategies of human groups that settled in Northwest South America since the Pleistocene/Holocene transition. To contextualize the analysis, a brief description of the Colombian Pleistocene sites is presented. The paper presents a broad description of the lithic technology, archaeobotanical record and radiocarbon dates. Plant resources played a key role in the settling of human groups in the forests of the Neotropics. Furthermore, it is suggested that for some areas there is evidence of cultivation as a strategy to increase the carrying capacity of the surrounding environment. [ABSTRACT FROM AUTHOR]

In this paper we present the results of the analysis of lithic industry from Vlakno Cave, which was discovered during excavations in 2004 and 2007. Radiocarbon dating positions the analysed lithic industry at the time of Pleistocene-Holocene transition. The technological and typological features of the lithic production show continuity during the abovementioned transition. Very clear continuity may also be observed in terms of the procurement of raw material, albeit with certain differences between the Late Upper Palaeolithic and Mesolithic, which could be the result of environmental changes. Certain adaptations of the hunter-gatherers from Vlakno to new environmental circumstances can also be traced through the more significant role of marine food sources and continental malacofauna in subsistence strategies during the Mesolithic. Vlakno cave was used as a residential base of a smaller group of hunter-gatherers at the time of the Pleistocene-Holocene transition. [ABSTRACT FROM AUTHOR]

Investigations of glacial lake sediments located near the modern altitudinal boundary of a larch forest (between 750-810 m absolute elevation) reveal continuous records of the vegetation and climate changes over the last 12000 years in the area of the Okhotsk-Kolyma divide. For the first time, the pollen accumulation rates (PAR), which are suggestive of pollen productivity, were used as a key indicator to interpret the response of alpine plant communities to climate changes. The palynological data imply that several forest line fluctuations of ∼100-200 m occurred during the Holocene. A belt of tundra dominated by shrub pine was first established beyond the forest line near 7650 ± 50 BP. The abrupt appearance of the shrub pine in the studied area is characteristic of a sharp vegetation boundary found in other records from the north of the Far East that corresponds to the Boreal-Atlantic boundary of the Holocene. The birch pollen zone, which occurs in the earlier portions of the records, is characteristic of the transition from the Pleistocene to the Holocene. [ABSTRACT FROM AUTHOR]

Based on the evidence of a recently excavated, sealed site, situated at Ruien “Rosalinde” in the Belgian Scheldt valley, the response of hunter-gatherers to changing climate at the transition from the temperate Allerød to the cold Younger Dryas is discussed. Radiocarbon dated to the end of the Allerød or the very beginning of the Younger Dryas, the site of Ruien provides the earliest evidence of a refined lithic technology characterized by the use of a soft stone hammer and the production of straight and regular blade(let)s from intensively prepared cores with two opposite platforms and sharp striking angles. In the course of the Younger Dryas and Early Pre-boreal this knapping method will become standard all over Europe, from the Tanged Point Technocomplex in the North to the (Epi)Laborian in the South. It contrasts sharply with the knapping style of previous lithic traditions, such as the late Federmesser/Azilian and Bromme Technocomplexes, which was much less elaborated and mainly oriented towards the knapping of short irregular blades with a hard stone hammer. This apparently abrupt technological change was also accompanied by increased raw material procurement networks, extending over up to 250 km, and a marked microlithisation of the hunting equipment. Finally, the site of Ruien is also important as it demonstrates the limited archaeological visibility of Younger Dryas sites, explaining the scarcity of such sites within western Europe. [ABSTRACT FROM AUTHOR]

Abstract: Southern Mendoza, Argentina, is characterised by abundant Pleistocene to Holocene volcanism associated with back-arc magmatism, influenced by the subducting Nazca plate. Age determinations in this volcanic area have been improved during the last 5 years. However, there are some volcanic features especially in the Payunia Volcanic Field (PVF) which suggest fairly recent eruptions and which have not been chronologically determined. Recent studies on the Llancanelo Volcanic Field (LLVF) and PVF have determined volcanic activity mainly using K–Ar and 40Ar/39Ar as well as cosmogenic 3He. However, K–Ar and 40Ar/39Ar fail to produce reliable ages in Holocene basaltic flows. To better constrain the younger volcanic activity in the LLVF and especially in the PVF, surface exposure dating using cosmogenic 3He and 21Ne was applied to five volcanic features. By applying this method, 3He and 21Ne ages ranging from late Pleistocene to mid Holocene were obtained for basalts from the area of Los Volcanes, from the PVF. The youngest age acquired is significant as it supports previous evidence for mid Holocene volcanic activity in the PVF and constitutes the first noble gas cosmogenic surface exposure age obtained from a basaltic bomb. This paper illustrates the advantages of using two nuclides (3He and 21Ne) for cosmic-ray exposure ages in the study of recent volcanic eruptions. The results in the present study indicate that the PVF was active in the last 5 ka. [Copyright &y& Elsevier]

Abstract: Spatial and temporal variations in evidence for human occupation of Argentinian south Patagonia closely resemble changes in past vegetation reconstructed from pollen records. The Antarctic Cold Reversal was cold and dry in the Deseado Massif and there is little evidence of humans at this time. In contrast, the Younger Dryas interval was warmer and slightly wetter and this was when humans moved into the Deseado area. Increasing temperatures during the early Holocene brought higher precipitation to much of Patagonia east of the Andes except the northern Deseado Massif, explaining the increase in evidence of human occupation in western areas and the decrease in evidence in the massif. Spatial and temporal variations in the frequency of radiocarbon dates indicating human presence, show that in southern Patagonia humans were not only influenced by the major climate shifts of the Pleistocene–Holocene transition but possibly also by distinct short-term changes lasting only a few to several centuries that are apparent in the high-resolution Antarctic Byrd ice core. Water availability may have had the greatest influence on human use of the landscape rather than temperature. However, as temperature is crucial in controlling the latitude of the core of the Southern Westerly Winds, associated with reduced precipitation over most of eastern Patagonia, it is difficult to separate water from temperature in examining impacts on the first humans in southernmost South America. [Copyright &y& Elsevier]

The sedimentary record of Lake Hazar has been documented by detailed seismo- and chronostratigraphic analyses using high-resolution seismic profiles and sediment cores. In this study, two main seismic stratigraphic units can be confidently correlated with sediment cores using lithology and physical properties. As a result of radiocarbon AMS dating, these sedimentary units presumably cover the period from the late Pleistocene to Holocene. The Holocene sequence of the lake infills can be subdivided into five subunits, each subject to distinctive hydrological and sedimentological processes due to fluctuating lake level. The elevations of these deposits including coastal paleo-terraces provide history of the lake level changes. In Lake Hazar, the maximum lowstand lake level occurred during the transition from the Younger Dryas to Holocene, when the −73 m wave-cut terrace was formed as the main shelf-crossing unconformity surface. The beginning of the Holocene was associated with a abrupt lake level rise and resultant deepening. Analysis of the Lake Hazar terraces has the potential to provide complementary data on the chronology of past lake level and lake volume changes, and their link to past climate change. The continued rising lake level during beginning of the Holocene was modulated by stillstands at −63 m and −56 m, as indicated by broad coastal paleo-terraces across the northern shelf. The main shelf-margin sedimentary system for the Holocene period is composed of three distinct buried deltaic-complexes that were presumably sourced from the Kürkçayı River, the largest input into Lake Hazar. The 3rd millennium crisis at around 3 14C ka BP is recorded in the seismic and core data when the cold and dry climatic condition gave rise to a significant lake level drop. [ABSTRACT FROM AUTHOR]

The extinction date of the giant flightless New Zealand ratite bird, the crested moa (Pachyornis australis), is of considerable interest because the youngest verified remains are dated to the Pleistocene–Holocene transition c. 10,000 yr BP, which was characterised by severe climatic and habitat change, and are considerably earlier than the late Holocene extinctions of the other eight moa species. Analysis of a partial crested moa skeleton (NMNZ S23569) from Castle Keep Entrance, Bulmer Cave System, Mount Owen, South Island, generated a radiocarbon date of 564±26 yr BP (544–508 cal yr BP; 95.4% AD 1396–1442). As a result the Bulmer Cave specimen represents the youngest moa yet found from a natural site in New Zealand. Combined with additional crested moa remains dated to the late Holocene from Cheops Cave (Mount Arthur) and Magnesite Quarry (Cobb Valley), this indicates that crested moa did not go extinct during the Pleistocene–Holocene transition but survived until after Polynesian colonisation in c. AD 1280. The new radiocarbon dates reported here have important implications for the timing of moa extinction and the late survival of moa in alpine areas of New Zealand. [ABSTRACT FROM AUTHOR]

Cave lions ( Panthera spelaea), which spread throughout Western Europe for several thousand years, disappeared approximately 14 000-14 500 years ago. They were supposedly replaced by modern lions ( Panthera leo) approximately 8000 years ago. Modern lions reached the steppes of Ukraine and Hungary, without penetrating the forests of Central Europe. The present study focuses on Italian and Spanish findings that possibly bridge the alleged absence of these big cats from Europe for 6000 years. Fossil lion remains from reliably radiocarbon-dated levels have been plotted against the δ18 O curve and mapped. The accumulated evidence indicates that lions inhabited Western Europe uninterruptedly from the early Middle Pleistocene up to the Early Holocene. Moreover, all of the latest Pleistocene/early Holocene lion-bearing localities do not range farther than the 44th parallel north and are located at relatively high altitudes. Two working hypotheses are formulated: one, which is less likely because it is not supported by palaeontological evidence indicating earlier migrations of lions from Africa, suggests that modern lions entered Western Europe prior to 8000 years ago; the second, which is more probable, suggests that P. spelaea (or an advanced offspring of the species) survived up until the latest Pleistocene. Panthera leo accessed Eastern Europe between 6000-6500 and 8000 years ago but was prevented from penetrating further west, probably because of the intrusive presence of their indigenous European relatives, and/or the increasing encroachment of modern human populations. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 109, 66-77. [ABSTRACT FROM AUTHOR]

The Florida Middle Ground is a complex of north to northwest trending ridges that lie approximately 180 km northwest of Tampa Bay, Florida. The irregular ridges appear on the otherwise gently sloping West Florida shelf and exhibit between 10-15 m of relief. Modern studies interpret the ridges as remnants of a Holocene coral-reef buildup that today provide a hard substrate for growth of a variety of benthic organisms including hydrocorals, scleractinians, alcyonarians, and algae. Recent rotary coring reveals that the core of the eastern ridge of the Florida Middle Ground complex consists of unconsolidated marine calcareous muddy sand that is capped by a boundstone composed primarily of the sessile vermetid gastropod Petaloconchus sp., and overlays a weathered, fossiliferous limestone. Accelerator Mass Spectrometry radiocarbon ages (uncalibrated) on the 3.6-m thick vermetid worm rock indicate that it developed during a sea-level stillstand in the early Holocene (8,225 ± 30-8,910 ± 25 yr B.P.). Our observations suggest that the Florida Middle Ground is a remnant of a series of shore parallel bars that formed in the early Holocene and were capped by a 3.6-m thick unit of vermetid gastropods. During a rapid sea-level rise that began ~8,000 yr B.P. the vermetids growth ceased and the worm rock preserved the ridges structure. Diver observations document that the edges of the ridges are currently being eroded and undermined by biological activity and current action, leading to calving of large capstone blocks. [ABSTRACT FROM AUTHOR]

Abstract: Despite the growing interest in megafans, definitions provided for this type of environmental setting have not yet been widely agreed upon. A record of sedimentary facies distribution in both space and time including a larger number of analogs is particularly needed for improving megafan facies models. This work focuses on a large fan-like feature from an Amazonian wetland in northern Brazil. Morphological data based on remote sensing, as well as sedimentary facies and radiocarbon analyses, were integrated to propose that this feature is related to a megafan system active during the Late Pleistocene to Holocene. The megafan displays a divergent drainage network, gently-dipping slope, and concave-up and convex-up longitudinal and transverse profiles, respectively. Near surface deposits correspond to fining and coarsening upward sands related to active channels and overbank sand sheets/terminal fan lobes. Sediments are interbedded with abandoned channel/floodplain and lake/pond muds. Morphostructural analyses and drainage anomalies revealed a geological setting affected by reactivation of pre-existing faults contemporaneous with sediment accumulation. Establishment of a megafan system in this wetland most likely occurred within a slightly tectonically subsiding basin under favorable climatic conditions. During wet seasons, high water discharge would have favored sediment transport from highlands into this depositional site. High summer temperatures and drought under a monsoonal regime kept the water levels low. The described megafan could serve as an analog for contemporary tropical wetland megafans formed under a monsoonal climate regime. [Copyright &y& Elsevier]

Abstract: Although the Asian monsoon is the dominant source of precipitation across continental Southeast Asia, projections of future climate trends in this region remain unclear. This is partly because historic climate records are relatively short, precluding our ability to understand long-term climate dynamics and potential drivers of change. In this synthesis, 17 palaeorecords from sites located in continental Southeast Asia provide a synopsis of regional palaeoclimate dynamics over the last ~30,000Calyrs BP. The results indicate that over millennial timescales, the dominant control on Asian monsoon intensity is solar insolation linked to orbital changes. From ca. 30 to 11.9Calkyr BP, climatic conditions are interpreted to have been cold and arid; most probably dominated by a strong Asian winter monsoon. Marked changes occurred during the Pleistocene–Holocene Transition, including a shift to warmer, wetter climatic conditions at ca. 11.5Calkyr BP, which was apparently synchronous across the region. During the early to mid Holocene, warmer, wetter climatic conditions were established, consistent with a strong Asian summer monsoon inferred from the Dongge Cave δ18O speleothem record. Intriguingly, contrasting sub-regional palaeoclimatic trends are captured in the synthesis; most notably during the Holocene, possibly due to differing sub-regional climatic and environmental influences (including differences in the role of the Asian monsoon, the Westerlies and/or topographical effects). However, because of uncertainties relating to the age control of many of the palaeorecords, it is not possible to make this interpretation with confidence. Further work involving comprehensive radiocarbon dating of sequences and the development of high-resolution palaeoclimatic reconstructions are urgently required if we are to identify decadal to centennial scale changes across continental Southeast Asia and test hypotheses of synchroneity in the region. [Copyright &y& Elsevier]

A recent study into prescreening techniques to identify bones suitable for radiocarbon dating from sites known for poor or variable preservation (Brock et al. 2007, 2010a) found that the percent nitrogen (%N) content of whole bone powder was the most reliable indicator of collagen preservation. Measurement of %N is rapid, requires little preparation or material, and is relatively cheap. The technique reduces the risk of needlessly sampling valuable archaeological objects, as well as saving time and money on their unsuccessful pretreatment prior to dating. This method of prescreening is now regularly used at the Oxford Radiocarbon Accelerator Unit (ORAU). In the original study, linear regression analysis of data from 100 bones from 12 Holocene sites across southern England showed that when 0.76% N was chosen as a threshold, 84% of bones were successfully identified as containing sufficient (i.e. >1%) or insufficient (i.e. <1%) collagen for dating. However, it has been observed that for older, Pleistocene bones the failure rate may be higher, possibly due to the presence of more degraded, shortchain proteins that pass through the ultrafilters used in pretreatment, resulting in lower yields. Here, we present linear regression analysis of data from nearly 600 human and animal bones, antlers, and teeth, from a wide range of contexts and ages, to determine whether the 0.76% threshold identified in the previous study is still applicable. The potential of carbon:nitrogen atomic weight ratios (C:N) of whole bone to predict collagen preservation is also discussed. [ABSTRACT FROM AUTHOR]

This paper contains lithostratigraphic and chronometric (radiocarbon dating) data on one of the regions on the Karelian coast of the White Sea obtained in the course of investigation of sedimentary sections from recent lake basins, which were separated at different times from the sea due to uplift of the glacioisostatic crust of the Earth. They were used as a basis for stratigraphic subdivision of marine and fresh water sediments and for reconstruction of the White Sea coast level change during the Late Pleistocene-Holocene near the Settlement of Kuzema, Karelia. [ABSTRACT FROM AUTHOR]

Abstract: The Whakatane Tephra, a rhyolitic tephra erupted ca. 5500 cal. BP from Okataina Volcanic Centre, central North Island, has been identified on the Chatham Islands which lie ∼900 km east of Christchurch, New Zealand. The visible tephra layer, ∼5 mm in thickness and preserved within peat on Pitt Island, was identified using both radiocarbon dating and analysis of glass shards by electron microprobe. Whakatane Tephra is the first Holocene tephra to be identified on the Chatham Islands, and it is the most-distal Holocene tephra yet recorded in the New Zealand region, being ∼850 km from source. The Pitt Island occurrence extends the tephra’s dispersal area markedly, by an order of magnitude, possibly to ∼300,000 km2. An estimated dispersal index (D) of approximately 105 km2 indicates that the eruption generated a very high plinian column, possibly exceeding ∼30 km in height, with strong winds blowing the ash plume southeastwards. This new discovery of distal Whakatane Tephra as a thin but visible layer strongly implies that cryptotephras are likely to be preserved on the Chatham Islands and within adjacent ocean floor sediments. Therefore the potential exists to develop enhanced cryptotephrostratigraphic records from these distal areas, which in turn would help facilitate precise correlation via tephrochronology of palaeoenvironmental records (such as NZ-INTIMATE) from mainland New Zealand, the southwest Pacific Ocean, and the Chatham Islands. [Copyright &y& Elsevier]

Abstract: Late Glacial and Holocene soils and sediments in southern Chile contain an important record of explosive volcanic activity since the end of the last glaciation, and have considerable potential for the development of a regional tephrostratigraphical framework. This paper reports the discovery of several new tephra deposits from the Hualaihue region (∼42° S) of southern Chile. Eruption sizes, constrained from field observations, and ages, constrained by 25 new radiocarbon dates, show that the volcanoes of the Hualaihue peninsula have had relatively few explosive, tephra-generating eruptions during the Holocene. An eruption of Apagado deposited ∼1 km3 of bedded basaltic scoria at ∼2.6 calibrated (cal) ka BP, and Hornopirén produced a similar, but volumetrically-smaller unit at ∼5.7 cal ka BP. Activity at Yate over the same time period has been predominantly characterised by lava production, although small explosive eruptions, the products of which span a range of compositions, have also occurred, including one at ∼0.9 cal ka BP. The northern part of the regional tephra sequence is dominated by andesitic pumice fall deposits derived from Calbuco volcano. These include deposits from several eruptions during a 3500-year-long period at the start of the Holocene, as well as two large explosive eruptions in the past 2000 years. A distinctive rhyolitic tephra layer that is interbedded with the locally derived tephra sequence is the Cha1 unit, from Chaitén volcano, 108 km south of Hornopirén. This rhyolitic pumice deposit, dated at ∼9.75 cal ka BP, is the largest volumetrically of those described here, with a volume of 3.5 km3. This new tephrostratigraphy covers a region whose volcanic history was previously very little known, and contributes to a regional record of large explosive eruptions that now spans a 500 km-long segment of the southern Andean arc, between Calbuco and Hudson volcanoes. [Copyright &y& Elsevier]

Up to 2.3 m long sediment sequences were recovered from the deepest part of Lake Hoare in Taylor Valley, southern Victoria Land, Antarctica. Sedimentological, biogeochemical, and mineralogical analyses revealed a high spatial variability of these parameters in Lake Hoare. Five distinct lithological units were recognized. Radiocarbon dating of bulk organic carbon samples from the sediment sequences yielded apparently too old ages and significant age reversals, which prevented the establishment of reliable age-depth models. However, cross correlation of the sedimentary characteristics with those of sediment records from neighbouring Lake Fryxell indicates that the lowermost two units of the Lake Hoare sediment sequences were probably deposited during the final phase of proglacial Lake Washburn, which occupied Taylor Valley during the late Pleistocene and early Holocene. High amounts of angular gravel and the absence of fine-grained material imply a complete desiccation with subaerial conditions in the Lake Hoare basin in the middle of the Holocene. The late Holocene (< c. 3300 calendar yr bp) is characterized by the establishment of environmental conditions similar to those existing today. A late Holocene desiccation event, such as proposed in former studies, is not indicated in the sediment sequences recovered. [ABSTRACT FROM AUTHOR]

Post-glacial, neritic cool-water carbonates of the Western Mediterranean Sea were examined by means of hydroacoustic data, sediment surface sampling and vibrocoring to unravel geometries and to reconstruct sedimentary evolution in response to the last sea-level rise. The analysed areas, located on the Alboran Ridge, in the Bay of Oran, and at the southern shelf of the island of Mallorca, are microtidal and bathed by oligotrophic to weakly mesotrophic waters. Seasonal water temperature varies between 13 °C and 27 °C. Echosounder profiles show that the Bay of Oran and the southern shelf of Mallorca are distally steepened ramps, while the Alboran Ridge forms a steep-flanked rugged plateau around the Alboran Island. In the three areas, an up to 10 m thick post-glacial sediment cover overlies an unconformity. In Oran and Mallorca, stacked lowstand wedges occur in water depths of 120 to 130 m. On the Alboran Ridge and in the Bay of Oran, highstand wedges occur at 35 to 40 m. Up to 5 m long cores of upper Pleistocene to Holocene successions were recovered in water depths between 40 and 81 m. Deposits contain more than 80% carbonate, with mixed carbonate-volcaniclastics in the lower part of some cores in Alboran. The carbonates consist of up to 53% of aragonite and up to 83% of high magnesium calcite. Radiocarbon dating of bivalve shells, coralline algae and serpulid tubes indicates that deposits are as old as 12 400 cal yr . The carbonate factories in the three areas are dominated mostly by red algae, but some intervals in the cores are richer in bivalves. A facies rich in the gastropod Turritella, reflecting elevated surface productivity, is restricted to the Mallorca Shelf. Rhodoliths occur at the sediment surface in most areas at water depths shallower than 70 m; they form a 10 to 20 cm thick veneer overlying rhodolith-poor bioclastic sediments which, nonetheless, contain abundant red algal debris. This rhodolith layer has been developing for the past 800 to 1000 years. Similar layers at different positions in the cores are interpreted as reflecting in situ growth of rhodoliths at times of reduced net sedimentation. Sedimentary successions in the cores record the post-glacial sea-level rise and the degree of sediment exposure to bottom currents. Deepening-upward trends in the successions are either reflected by shallow to deep facies transitions or by a corresponding change of depth-indicative red algae. There are only weak downcore variations of carbonate mineralogy, which indicate that no dissolution or high magnesium to low magnesium calcite neomorphism occurs in the shallow subsurface. These new data support the approach of using the Recent facies distribution for interpretation of past cool-water, low-energy, microtidal carbonate depositional systems. Hydroacoustic data show that previous Pleistocene transgressive and highstand inner ramp deposits and wedges were removed during sea-level lowstands and accumulated downslope as stacked lowstand wedges; this suggests that, under conditions of high-amplitude sea-level fluctuations, the stratigraphic record of similar cool-water carbonates may be biased. [ABSTRACT FROM AUTHOR]

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Abstract: A chronostratigraphic framework is constructed from sediments surrounding an active gas-hydrate and cold-seep field, situated on the northern Gulf of Mexico slope within federal offshore lease block Mississippi Canyon 118 (MC118). Accelerator mass spectrometer (AMS) radiocarbon dating, foraminiferal biostratigraphy and nannofossil biostratigraphy are used to constrain the age of sediments from 10 gravity cores collected around the field. X-ray fluorescence (XRF) core scanning is employed to develop continuous down-core elemental profiles, which are used to evaluate biogenic calcium and siliciclastic titanium sediment inputs, and provide a means to correlate sediments across the study area and infer changes in sedimentation through time. Spatial reconstruction of sedimentation surrounding the field indicates the following: (1) a consistent pattern of stratigraphic thinning in close proximity to the field over the past 14,000yrs and (2), temporal changes in sedimentation that primarily reflect deglacial sea-level rise as well as regional factors such as Mississippi delta lobe switching. These results highlight the variability of sedimentation along a continental slope setting where marine cold seeps and gas hydrate persist, yet do not suggest slope failure or destabilization of the seafloor at this site, at least during the past 14,000yrs. The evaluation of sedimentation at this location provides an important context for ongoing biogeochemical and geophysical monitoring of the MC118 site, which has been designated the first National Gas Hydrate Seafloor Observatory by the Gulf of Mexico Hydrate Research Consortium. [ABSTRACT FROM AUTHOR]

The causes of the late Pleistocene megafaunal extinctions are poorly understood. Different lines of evidence point to climate change, the arrival of humans, ora combination of these events as the trigger. Although many species went extinct, others, such as caribou and bison, survived to the present. The musk ox has an intermediate story: relatively abundant during the Pleistocene, it is now restricted to Greenland and the Arctic Archipelago. In this study, we use ancient DNA sequences, temporally unbiased summary statistics, and Bayesian analytical techniques to infer musk ox population dynamics throughout the late Pleistocene and Holocene. Our results reveal that musk ox genetic diversity was much higher during the Pleistocene than at present, and has undergone several expansions and contractions over the past 60,000 years. Northeast Siberia was of key importance, as it was the geographic origin of all samples studied and held a large diverse population until local extinction at ≈45,000 radiocarbon years before present (14C YBP). Subsequently, musk ox genetic diversity reincreased at ca. 30,000 14C YBP, recontracted at ca. 18,000 14C YBP, and finally recovered in the middle Holocene. The arrival of humans into relevant areas of the musk ox range did not affect their mitochondrial diversity, and both musk ox and humans expanded into Greenland concomitantly. Thus, their population dynamics are better explained by a nonanthropogenic cause (for example, environmental change), a hypothesis supported by historic observations on the sensitivity of the species to both climatic warming and fluctuations. [ABSTRACT FROM AUTHOR]

Abstract: A combination of three relative and two absolute (numerical) dating techniques, applied on nine soil profiles in an Alpine environment located in Val di Rabbi (Trentino, Northern Italy), was used to improve the investigation methodology of Alpine sites in response to climate change and to reconstruct the chronology of late Pleistocene and early Holocene landscape evolution. The degree of podzolisation, clay mineral evolution and the element mass balances of each site were investigated. Furthermore, the stable fraction of the soil organic matter (SOM) was extracted with 10% H2O2 and 14C-dated. The age of the organic residues was compared with the age of charcoal fragments found in one of the studied soils and with the age of rock boulders obtained by surface exposure dating (SED) with cosmogenic 10Be. Numerical dating and weathering characteristics of the soils showed a fairly good agreement and enabled a relative and absolute differentiation of landscape elements. The combination of 14C-dating of SOM and SED indicated that deglaciation processes in Val di Rabbi were already far advanced by around 14000 cal BP and that glacier oscillations affected the highest part of the region until about 9000 cal BP. The development of clay minerals is time-dependent and reflects weathering intensity. We found a close link between secondary clay minerals like smectite or vermiculite and soil age as obtained by the dating of the organic residues after the H2O2 treatment. Calculated element mass balances strongly correlated with the ages derived from 14C measurements. Old soils have lost a major part of base cations (up to 75% compared to the parent material), Fe and Al, which indicates a continuous high weathering intensity. Results of the chemical and mineralogical analyses were in good agreement with numerical dating techniques, showing the dynamics of an Alpine landscape within a relatively small area. The combination of relative and absolute dating techniques is a promising tool for the reconstruction of landscape history in high-elevation Alpine areas on siliceous substrates. [Copyright &y& Elsevier]

Abstract: The Tepexpan Palaeoindian skeleton was discovered in 1947 close to the former Lake Texcoco margin, in the Basin of Mexico. The find has been the object of considerable interest and discussion over the last 60years regarding its real age and archaeological interpretation. Here we report new AMS radiocarbon dates associated with the sedimentary succession at Tepexpan with ages between 19,110±90 and 612±22 14C years BP and a new uranium-series date for the skeleton with an age of 4700±200years BP that indicates a mid Holocene age. The sedimentary succession was studied in detail using: stable isotopes, diatoms, organic geochemistry and tephrochronology. The multi-proxy evidence suggests large changes around the margins of Lake Texcoco in terms of the balance between aquatic and terrestrial plants, C3 and C4 plants, saline, alkaline and freshwater conditions, volcanic activity, marginal reworking of lake sediments and input from the drainage basin through the late Pleistocene–late Holocene. These changes had large impacts on the prehistoric human populations living by the lake shores since the late Pleistocene in the Basin of Mexico. [Copyright &y& Elsevier]

Abstract: The Late Pleistocene to Middle Holocene African Humid Period (AHP) was characterized by dramatic hydrologic fluctuations in the tropics. A better knowledge of the timing, spatial extent, and magnitude of these hydrological fluctuations is essential to decipher the climate-forcing mechanisms that controlled them. The Suguta Valley (2°N, northern Kenya Rift) has recorded extreme environmental changes during the AHP. Extensive outcrops of lacustrine sediments, ubiquitous wave-cut notches, shorelines, and broad terrace treads along the valley margins are the vestiges of Lake Suguta, which once filled an 80km long and 20km wide volcano–tectonic depression. Lake Suguta was deep between 16.5 and 8.5calkaBP. During its maximum highstand, it attained a water depth of ca 300m, a surface area of ca 2150km2, and a volume of ca 390km3. The spatial distribution of lake sediments, the elevation of palaeo-shorelines, and other geomorphic evidences suggest that palaeo-Lake Suguta had an overflow towards the Turkana basin to the north. After 8.5calkaBP, Lake Suguta abruptly disappeared. A comparison of the Lake Suguta water-level curve with other reconstructed water levels from the northern part of the East African Rift System shows that local insolation, which is dominated by precessional cycles, may have controlled the timing of lake highstands in this region. Our data show that changes of lake levels close to the Equator seem to be driven by fluctuations of spring insolation, while fluctuations north of the Equator are apparently related to variations in summer insolation. However, since these inferred timings of lake-level changes are mostly based on the radiocarbon dating of carbonate shells, which may have been affected by a local age reservoir, alternative dating methods are needed to support this regional synthesis. Between 12.7 and 11.8calkaBP, approximately during the Northern Hemisphere high-latitude Younger Dryas, the water level of Lake Suguta fell by ca 50m, suggesting that remote influences also affected local hydrology. [Copyright &y& Elsevier]

This research reports on a synthesis of radiocarbon (14C) dates and the organic content from a variety of depositional sites in a relatively small region in humid eastern Australia centred on Sydney. We focused on basal dates, changes in accumulation rates and the organic content of these sediment records in the period post-dating 21 thousand years ago to make inferences about past environmental conditions, or to infer the timing of past environmental change. We found that low rates of sediment and organic accumulation at the Last Glacial Maximum continued well into the late Pleistocene. The average rate of sediment deposition and organic content increased from about 14.5 calibrated kiloanni before present (cal ka BP), perhaps coincident with Meltwater Pulse 1A, but this was then checked by dry conditions during the Antarctic Climatic Reversal chronozone. An abrupt increase in the average rate of sediment accumulation coincided with the Pleistocene-Holocene boundary (at 11.7 cal ka BP), and this continued until about 9.2 cal ka BP, largely coinciding with the Antarctic thermal maximum, and probably reflecting reduced moisture availability in the Sydney region. Indication of depressed temperature and a more positive moisture availability, from about 9 to 7.6 cal ka BP, witnessed the fastest increase in the number of sites than at any other time. An overall drier early Holocene abruptly altered at about 7.5 cal ka BP and a mid-Holocene 'optimum' in moisture availability extended to 6.2 cal ka BP. The compilation of organic contents of the mid-late Holocene suggests environmental variability, but El Niño frequency or strength is not implicated as a driving force. Increased organic productivity, especially after 2.8 cal ka BP, corresponded to a peak in summer insolation, and associated seasonality of insolation and this is likely to have resulted in increased, or more consistent, summer rainfall and easterly air flow into the Sydney region. In contrast to previous generalisations about changes in south-eastern Australia during the Holocene, which have often relied on palaeoenvironmental records from further south, the southward migration of the intertropical convergence zone during the Holocene had vastly different synoptic outcomes in the Sydney region, with the early Holocene drier as continental air dominated, and the late Holocene wetter, as the synoptic conditions saw more tropical and easterly airflow. This work demonstrates the danger in making generalisations across regions and highlights the utility of the compilation of data at a homoclimatic, regional scale. • New syntheses of sediment accumulation and organic content from sites centred on the Sydney Basin in eastern Australia. • Challenging conditions continued well after the LGM, and this included a dry Antarctic Climatic Reversal. • The region was drier in the early and wetter in the late Holocene, reflecting the interplay between moisture sources. • The drier early Holocene abruptly ended at ∼7.5 cal ka BP and enhanced moisture availability then extended to 6.2 cal ka BP. • In the late Holocene insolation likely drove increased summer rainfall and easterly air flow into the Sydney region. [ABSTRACT FROM AUTHOR]

Radiocarbon dates of incorporated moss indicate advance of the Collins Ice Cap on Fildes Peninsula (King George Island) after ∼650 cal. yr BP (∼AD 1300), broadly contemporaneous with the 'Little Ice Age', as defined in Europe. During that time, the glacier extended less than 400-500 m beyond its present-day margin. Moreover, radiocarbon data indicate that this was the most extensive advance of the last 3500 cal. years. Prior to ∼650 cal. yr BP, the ice must have been at or behind its present position. Furthermore, the data indicate that climate conditions prior to the late-Holocene advance may have been similar to (or possibly warmer than) today. [ABSTRACT FROM AUTHOR]

Walker Lake is a terminal lake located at the end of the Walker River in western Nevada. Lake-level lowering of ∼50 m during the past 100 yr has led to deep incision by the Walker River into the former lake bed. This incision has exposed a sedimentary record of lake-level fluctuations spanning at least the past 4000 yr. Fourteen new radiocarbon dates on plant material collected from diverse sedimentary environments, including fluvial, deltaic, beach, and offshore settings, have led to the refinement of the late Holocene lake-level curve for this basin. This new curve documents at least four highstands that have occurred since ca. 3500 cal yr B.P. between elevations of 1245 and 1255 m. The lake has also experienced several lowstands during this same period. Comparison of this outcrop-based record to existing lake-level curves and to an oxygen isotope curve for the past 1200 yr reveals many similarities between the records, but also some differences. Therefore, research should be conducted to integrate outcrop studies, where absolute water depth and lake volume can be estimated, with isotopic or other types of proxies from cored sediments that may have higher temporal resolution. The extensive and nearly continuous outcrops along the lower Walker River also provide valuable information on the relationships between various sedimentary features and their formative water depths in clastic-dominated lacustrine systems. The paleo-water depth relationships deciphered here can be applied in other basins, where outcrops are typically more limited, to arrive at better-constrained lake-level records. [ABSTRACT FROM AUTHOR]

Abstract: A detailed investigation of geomorphological evidence of paleoshorelines and exposed stratigraphic sections of lake deposits, combined with a chronology based on radiocarbon dated charcoal and in-situ 14C dating of wave polished bedrock, provide important new constraints on lake level changes of Lake Bosumtwi, Ghana. Thick sequences of laminated silts, alternating with transgressive sands and deltaic gravels, attest to a long history of climatically controlled lake level variations. The post-glacial rise in lake level began sometime after 16.3 ka, reached stable levels first at 14.5±0.6 ka and then rose again after ca. 14.3 ka. A significant lake level regression spanned the interval from 12.6±0.3 to 11.6±0.5 ka, synchronous with the Younger Dryas. Deep lake conditions were reestablished after ca. 11 ka, at which time the lake overtopped the crater. Overflow continued until 8.8±0.5 ka, when another significant but short-lived regression occurred. Deep, but probably not overflowing conditions were again reestablished by >7.2±0.3 ka and continued until around 3.2±0.1 ka, when lake level dropped precipitously. Multicentury late Holocene highstands occurred at 2.2±0.1 and 1.7±0.2 ka, although these were significantly lower than those registered in the late glacial and early Holocene. The timing of late glacial events is similar to those recorded elsewhere in Africa and the higher latitudes, and likely reflects the dominant control of high latitude northern hemisphere conditions on the African tropics during the times of large northern hemisphere ice sheets. Mid- to late-Holocene variations appear to be less coupled with changes across Africa and elsewhere, suggesting that regional forcing may be more important during warmer periods. [Copyright &y& Elsevier]

Isla de Cedros is a high, rocky island located on the Pacific Coast of Baja California 685 km south of San Diego. Its arid but temperate marine climate provides excellent conditions of archaeological preservation and visibility. Over the last five years, the Proyecto Arqueologico Isla de Cedros has documented a diverse and rich archaeological record on the island. In addition to many more recent deposits, at least two coastal shell middens have been identified that were occupied during the Early Holocene and Terminal Pleistocene. Initial investigation of these sites, including 14C dating and limited excavations at the largest and most intact example (PAIC-44, Cerro Pedregoso), provides an opportunity to address issues related to the nature and antiquity of maritime adaptations along the eastern Pacific Rim, and potentially the peopling of the New World. [ABSTRACT FROM AUTHOR]