Cal Ky BP Research Articles

The deglaciation of Barton Peninsula (King George Island, South Shetland Islands, Antarctica) based on geomorphological evidence and lacustrine records

AbstractBarton Peninsula is an ice-free area located in the southwest corner of King George Island (South Shetland Islands, Antarctica). Following the Last Glacial Maximum, several geomorphological features developed in newly exposed ice-free terrain and their distribution provide insights about past environmental evolution of the area. Three moraine systems are indicative of three main glacial phases within the long-term glacial retreat, which also favoured the development of numerous lakes. Five of these lakes were cored to understand in greater detail the pattern of deglaciation through the study of lacustrine records. Radiocarbon dates from basal lacustrine sediments enabled the reconstruction of the chronology of Holocene glacial retreat. Tephra layers present in lake sediments provided additional independent age constraints on environmental changes based on geochemical and geochronological correlation with Deception Island-derived tephra. Shrinking of the Collins Glacier exposed the southern coastal fringe of Barton Peninsula at 8 cal ky BP. After a period of relative stability during the mid-Holocene, the ice cap started retreating northwards after 3.7 cal ky BP, confining some glaciers within valleys as shown by moraine systems. Lake sediments confirm a period of relative glacial stability during the last 2.4 cal ky BP.

HOLOCENE ENVIRONMENTAL CHANGE IN SOUTH-EAST ALTAI EVIDENCED BY SOIL RECORD

The soils of Russian Altai highlands were used as a paleoenvironmental archive, as a source of dating material, and as a chronostratigraphic marker to describe Holocene environmental change in the studied area. Based on calibration intervals of 14C dates obtained for buried humus horizons (11 buried soils in 6 studied soil-sedimentary sequences) and some dates from pendants of contemporary soils, following stages of pedogenesis were recorded in studied soil-sedimentary systems and surface soils: 6.4 – 11.5 ky cal BP; about 4.9-5.3 cal BP; 2.5-3.8 cal BP; 0.6 – 1.2 cal BP. All studied surface soils in the basins nowadays develop in cold, ultra-continental water deficit conditions: Skeletic Kastanozems Cambic, Skeletic Cambisols Protocalcic, Skeletic Cambic Calcisol Yermic. The most extreme conditions of soil formation within Holocene were within the last 1-2 kyr. All buried soils were formed in better conditions, more balanced in water, with higher biological activity, mostly within steppe or forest-steppe landscapes. Cryogenic features had been insisting all over the Holocene till nowadays. Water demandant cryogenic features are met in buried soils up to the age of 1-2 ky cal BP. In the last millennia cryogenic processes are suppressed, water demandant features gave way to those which can be formed in contemporary water deficit conditions: simple fissures, frost sorting, and shattering. At lower levels (Kuraj basin) more or less arid cold steppe conditions insisted within the most part of Holocene. Initial stages of soil formation were often ground water affected, or at least shortly waterlogged. At the highest positions humid and relatively warm Early Holocene stage of forest pedogenesis is recorded for the beginning of Holocene, and a Late Holocene (last 3-4 kyr) cold humid phase, presumably under mountain tundra and/or alpines. Microsedimentary intra-soil record in carbonatehumus pendants imprints fine fluctuations of soil water regime at initial stages of soil formation, controlled by local topography, and climatic changes in the second half of Holocene. General trends of environmental changes in the region recorded in soil and soil sedimentary systems are in well correspondence with other records of paleonvironment.

The Middle-Upper Paleolithic transition in Northwest Italy: new evidence from Riparo Bombrini (Balzi Rossi, Liguria, Italy)

We report here preliminary results from four seasons of excavation at the rockshelter of Riparo Bombrini (2002–2005). Three markedly separate horizons were uncovered: the deepest, comprising Levels M1-7, yielded abundant Mousterian lithics and faunal remains. A second macro-unit, corresponding to Levels MS1-2, is only a few decimeters thick and is characterized by the presence of large limestone blocks from partial collapse of the shelter's vault. The scarcity of material and presence of carnivore coprolites suggest sporadic human occupation. The third macro-unit, constituted by Levels A1-3 and following immediately above Levels MS1-2, contains a rich Proto-Aurignacian industry, including Dufour bladelets, bone tools, abundant ochre, numerous decorative objects (mainly perforated shells) and widespread use of exotic raw material. New AMS dates and stratigraphic and sedimentological evidence indicate that the appearance of the Proto-Aurignacian at Bombrini dates to around 41 ky cal BP, in a phase of climatic degradation, paralleling the conditions observed for the transition at other northern Italian sites. While preliminary faunal analysis suggests little change in site use over time, the composition of the lithic assemblages point to a marked technological discontinuity between the two time periods. Riparo Bombrini's stratigraphic sequence affords important details about the environmental and cultural dynamics that marked the expansion of modern humans into Europe and the disappearance of Neandertals in that region during OIS 3. The association of a rich Proto-Aurignacian complex with an anatomically modern deciduous human tooth enhances further its importance for understanding early Upper Paleolithic in Italy.

Longa duração e territorialidade da ocupação sambaquieira na laguna de Santa Marta, Santa Catarina

Este trabalho versa sobre a ocupação da região da laguna de Santa Marta, litoral sul catarinense, por grupos construtores de sambaquis. O período considerado vai aproximadamente de 7.5 a 0.9 cal ka aP, ao longo do qual a região esteve continuamente ocupada pelos grupos sambaquieiros. O resultado mostra que a dinâmica do processo de construção de sambaquis na região pode ser dividida em fases, uma de expansão, entre 7.5 e 3.0 ka aP, e outra de retração, de 3.0 a 0.9 ka aP. Ao longo de todo o período percebe-se um padrão de agregação dos sítios, com a região sendo particionada e compartilhada por vários focos de ocupação. Este padrão de territorialidade se manteve ao longo do tempo.

Compatible ecological niche signals between biological and archaeological datasets for late-surviving Neandertals.

To assess ecological niche similarity for biological and archaeological samples representing late-surviving Neandertals in Europe to evaluate the validity of combining these two types of data in ecological niche modeling analyses. Tests of niche conservatism were used to assess niche similarity and niche identity of samples of morphologically diagnostic Neandertal remains and Middle Paleolithic (MP) archaeological sites dating to the time period leading up to Neandertal extinction. Paleoenvironmental reconstructions for the Pre-H4 (43.3-40.2 ky cal BP) were used as environmental space analyses. Null hypotheses of niche similarity and identity of the two types of samples could not be rejected. As primary and secondary evidence of Neandertal occurrence during the Pre-H4 show high levels of niche similarity and identity, combining the two types of occurrence data to create larger samples for niche analyses is justified without the concern that different environmental signals could complicate future research.

Holocene environmental variability in the Central Ebro Basin (NE Spain) from geoarchaeological and pedological records

Environmental fluctuations during the Holocene caused important landscape changes in the Central Ebro Basin, which is a very sensitive region due to its semiarid climate, lithology, and continuous human presence. Severe erosion processes hinder palaeoenvironmental and archaeological record preservation. Infills of ephemeral stream valleys in semiarid environments are some of the best contexts for geoarchaeological studies. In this paper, we analyse the geomorphological processes, pedological features, and charcoal and pollen content and composition of the sedimentary sequence of La Poza Valley catchment area, with the support of additional information from La Bajada Valley. 14C dates for 13 charcoal fragments provide the necessary chronological control. We describe 5 sedimentary units and a polycyclic sequence of six soils that covers most of the Holocene, beginning ca. 9.5ky cal BP. Buried soils help to identify stability periods in the sedimentary sequence, while incision stages are detected through erosive contacts and terraced organisation of the sedimentary units. Charcoal and pollen content and composition, as well as the soil development, reveal an open forest of junipers and pines for the Early Holocene in the lower part of the sequence (mainly in Unit 1), very different from the current deforested landscape, also represented in the sequence (Unit 4). Thus, La Poza record shows the environment was favourable for hunter-gatherers from the Late Mesolithic and for the first Neolithic farmers. From then on, progressive degradation due to a combination of climate changes and increasing human pressure led to the current deforested landscape.

Exploring Neanderthal skills and lithic economy. The implication of a refitted Discoid reduction sequence reconstructed using 3D virtual analysis

Lithic refitting studies have consistently contributed to address two specific research aims: the intra-site mobility and identification of preferential areas or latent structures, and the in-depth analysis of the knapping technologies and core reduction strategies. Multiple refits, in particular, can produce highly detailed data on knapped stone technology. Elucidating human skills and lithic economy, a potential still rarely evaluated for Discoid technology: a stone knapping method largely spread across the Middle Paleolithic of Europe. The opportunity to explore Neanderthal knapping behavior is provided from the remarkable discovery of a primary lithic waste concentration in the Mousterian Discoid level of the Grotta di Fumane, Italy, dated to at least 47.6 ky cal BP. With a combined approach that included the 3D virtual interaction, we were able to reproduce a complete reduction sequence that supports the technological analysis conducted on the lithic assemblage. Results lead to a better comprehension of the knapper's technological and technical behavior, including the detection and quantification of economic objectives and productivity.

Reconstructing Last Glacial Maximum and Younger Dryas paleolandscapes through subsurface paleosol stratigraphy: An example from the Po coastal plain, Italy

Paleosols are commonly used to reconstruct ancient landscapes and past environmental conditions. Through identification and subsurface mapping of two pedogenically modified surfaces formed at the onset of the Last Glacial Maximum (LGM) and during the Younger Dryas (YD) cold event, respectively, and based on their lateral correlation with coeval channel-belt sand bodies, we assessed the geomorphic processes affecting the Po coastal plain during the Late Pleistocene (30–11.5calky BP). The 3D-reconstruction of the LGM and YD paleosurfaces provides insight into the paleolandscapes that developed in the Po alluvial plain at the transitions between warm and cold climate periods. The LGM paleosol records a stratigraphic hiatus of approximately 5kyr (29–24calky BP), whereas the development of the YD paleosol was associated with a climatic episode of significantly shorter duration. Both paleosols, dissected by Apennine rivers flowing from the south, dip towards the north-east, where they are replaced by fluvial channel belts fed by the Po River. The LGM channel-belt sand body reflects the protracted lateral migration of the Po River at the onset of the glacial maximum. It is wider (>24km) and thicker (~15m) of the fluvial sand body formed during the YD. The northern margin of LGM Po channel-belt deposits was not encountered in the study area. In contrast, a spatially restricted paleosol, identified in the north at the same elevation as the southern plateau, may represent local expression of the Alpine interfluve during the YD event. This study highlights how 3D-mapping of regionally extensive, weakly developed paleosols can be used to assess the geomorphic response of an alluvial system to rapid climate change.

The imprint of Late Holocene tectonic reactivation on a megafan landscape in the northern Amazonian wetlands

The modern Amazonian ecosystem outcomes from the complex interplay of different factors performed over the geological history, with tectonics being long speculated as perhaps a fundamental one. Nevertheless, areas where tectonic activity can be fully characterized are still scarce in view of the large dimension of this region. In this work, we investigate the signature of neotectonics in one megafan paleolandform that typifies a large sector of the Negro-Branco basin in northern Amazonia. The approach joined regional morphostructural descriptions of the Viruá megafan surface and the acquisition of topographic, sedimentological, and chronological data focusing on the central sector of the megafan. The results revealed an abundance of rivers that form dendritic, subdendritic, and trellis patterns. These rivers also have numerous straight segments, orthogonal junctions, and orthogonal shifts in courses. Structural lineaments, defined by straight channels and also straight lake margins, are aligned along the NW-SE and NE-SW directions that are coincidental with the main regional structural pattern in Amazonia. This study also led to recognize two large areas of lower topography in the south-central part of the megafan that consist of rectangular depressions parallel to the morphostructural lineaments. A sedimentological survey indicated that cores extracted external to the largest depression have only distributary channel and overbank sand sheet megafan deposits. Optically stimulated luminescence (OSL) ages ranged from 17.5±2.0 to 46.9±3.4ky and radiocarbon ages ranged from 5.9–5.7 to 20.1–19.6calky BP. In contrast, cores extracted within the depression consisted of fluvial deposits younger than 2.1–1.9calky BP that increased in thickness toward the central part of the depression. We propose that the studied megafan was affected by tectonic reactivation until at least a couple thousand years ago. Tectonics would have produced subsiding areas more prone to flooding than adjacent terrains, which constituted sites for renewed deposition of fluvial sediments reworked from the megafan surface following its abandonment. A comparison of our data with those from other Amazonian areas with similar records of late Holocene tectonics suggests a landscape imprinted by faulting, probably of strike-slip motion. This finding increases the record of neotectonic activity in the Amazonian wetlands and may be useful in studies aiming at discussing the origin and extension of late Holocene deformation in the South American intraplate. In addition, we present a megafan with an unusual development in a cratonic region under the combined effect of climate and tectonics.

Global sea-level control on local parasequence architecture from the Holocene record of the Po Plain, Italy

Holocene deposits exhibit distinct, predictable and chronologically constrained facies patterns that are quite useful as appropriate modern analogs for interpreting the ancient record. In this study, we examined the sedimentary response of the Po Plain coastal system to short-term (millennial-scale) relative fluctuations of sea level through high-resolution sequence-stratigraphic analysis of the Holocene succession.Meters-thick parasequences form the building blocks of stratigraphic architecture. Above the Younger Dryas paleosol, a prominent stratigraphic marker that demarcates the transgressive surface, Early Holocene parasequences (#s 1–3) record alternating periods of rapid flooding and gradual shoaling, and are stacked in a retrogradational pattern that mostly reflects stepped, post-glacial eustatic rise. Conversely, Middle to Late Holocene parasequences (#s 4–8) record a complex, pattern of coastal progradation and delta upbuilding that took place following sea-level stabilization at highstand, starting at about 7 cal ky BP. The prominent transgressive surface at the base of parasequence 1 correlates with the period of rapid, global sea-level rise at the onset of the Holocene (MWP-1B), whereas flooding surfaces associated with parasequences 2 and 3 apparently reflect minor Early Holocene eustatic jumps reported in the literature. Changes in shoreline trajectory, parasequence architecture and lithofacies distribution during the following eustatic highstand had, instead, an overwhelming autogenic component, mostly driven by river avulsions, delta lobe switching, local subsidence and sediment compaction. We document a ∼1000-year delayed response of the coastal depositional system to marine incursion, farther inland from the maximum landward position of the shoreline. A dramatic reduction in sediment flux due to fluvial avulsion resulted in marine inundation in back-barrier position, whereas coastal progradation was simultaneously taking place basinwards.We demonstrate that the landward equivalents of marine flooding surfaces (parasequence boundaries) may be defined by brackish and freshwater fossil assemblages, and traced for tens of kilometers into the non-marine realm. This makes millennial-scale parasequences, whether auto- or allogenic in origin, much more powerful than systems tracts for mapping detailed extents and volumes of sediment bodies.The Holocene parasequences of the Po coastal plain, with strong age control and a detailed understanding of sea-level variation, may provide insight into the driving mechanisms and predictability of successions characterized by similar depositional styles, but with poor age constraint, resulting in more robust interpretations of the ancient record.

Buried in ashes: Site formation processes at Lapa do Santo rockshelter, east-central Brazil

Few archaeological sites in the Americas contain high concentrations of human burials dating back to the early Holocene. The tropical karstic region of Lagoa Santa, in central Brazil (state of Minas Gerais) is one of the richest bioanthropological records available to study the behaviors and funerary practices of early Holocene South Americans, with more than 200 skeletons found so far. One of the key locations to examine the history of human settlement in Lagoa Santa is the site of Lapa do Santo, a rockshelter known to contain the oldest rock art and the earliest evidence of funerary complexity in the continent. In this geoarchaeological investigation we focus on the early Holocene settlement at Lapa do Santo (7.9–12.7 cal kyBP) applying high-resolution geoarchaeological techniques, such as micromorphology, organic petrology and μFTIR, on both archaeological, modern reference and experimental samples. This is the first time that a micro-contextual approach integrated with experimental geoarchaeology has been applied to study the formation of rockshelter deposits in a tropical setting. Our results show that the stratigraphic sequence formed under the dual influence of anthropogenic sedimentation—through continuous combustion activities—and geogenic sedimentation in the form of oxisol aggregates which fell from above the limestone cliff into the rockshelter. Intact hearths and remobilized combustion debris, possibly hearth rake-out, are close to the graves suggesting repeated burning activities as part of the ritual behavior of early Holocene South Americans. Large amounts of ash are intermixed with heated and unheated oxisol aggregates. Heated termite mound fragments were also found mixed within the sediments. Post-depositional alteration of the site includes limited bioturbation and localized, low energy surface water and sub-surface concentrations of moisture, leading to precipitation of dense, secondary carbonates. The age inversions can be attributed to the human action of reworking the ashy sediments and not to post-abandonment processes. Despite this, the overall preservation of the sediments is good and most human burials can be considered to be in primary context.

The Eurasian mammoth distribution during the second half of the Late Pleistocene and the Holocene: Regional aspects

Based on geographic information (database PALEOFAUNA), in combination with 14C and other methods of paleo dating (1584 localities, 4033 dates, including 1501 direct dates), we first examined details of changes of mammoth distribution in Eurasia on the whole and in single parts of the range over the last 50ky. The analysis of regional features in the dynamics of mammoth range and the quantity of dated localities acknowledged a leading role of the climatic (environmental) factor in these processes. The maximum size of the Eurasian range, the largest number of remains of mammoths from dated localities and, probably, the maximum total number of population were established for the range of 38.2–8.6 cal ky BP (Denekamp interstadial = Bryansk interstadial). In Western and Central Europe, the increase of population was observed during Huneborg stadial (40.8–38.2 cal ky BP). In eastern Siberia, the maximum population growth occurred in the Last Glacial Maximum (28.6–22.5 cal ky BP), and in Western Siberia – during Deglaciation (22.5–14.7 cal ky BP). The population dynamics at the periphery of the range (Islands of Japan, British Isles, Northern Europe, Southern Siberia and Northern China, and, but to lesser extent, South-Eastern Europe) differs from the dynamics of its main part. The southernmost parts of the range – Southern Siberia and southeastern Europe experienced similar changes. Population dynamics in the Iberian Peninsula was much alike the changes in Western and Central Europe. We suggested that some peripheral populations could periodically be isolated from the populations of the main part of the range. Direct calibrated radiocarbon dates fixed upper boundary of extinction of this species in different parts of range within time interval from 21 (the Iberian Peninsula) to 4 (northeastern Siberia) thousands years BP. The hypotheses about the causes of the dynamics of the area and population of the mammoth in Eurasia, including those related to the extinction of certain genetic lines of a mammoth in the Late Pleistocene, are being discussed.

The mitogenome of a 35,000-year-old Homo sapiens from Europe supports a Palaeolithic back-migration to Africa.

After the dispersal of modern humans (Homo sapiens) Out of Africa, hominins with a similar morphology to that of present-day humans initiated the gradual demographic expansion into Eurasia. The mitogenome (33-fold coverage) of the Peştera Muierii 1 individual (PM1) from Romania (35 ky cal BP) we present in this article corresponds fully to Homo sapiens, whilst exhibiting a mosaic of morphological features related to both modern humans and Neandertals. We have identified the PM1 mitogenome as a basal haplogroup U6*, not previously found in any ancient or present-day humans. The derived U6 haplotypes are predominantly found in present-day North-Western African populations. Concomitantly, those found in Europe have been attributed to recent gene-flow from North Africa. The presence of the basal haplogroup U6* in South East Europe (Romania) at 35 ky BP confirms a Eurasian origin of the U6 mitochondrial lineage. Consequently, we propose that the PM1 lineage is an offshoot to South East Europe that can be traced to the Early Upper Paleolithic back migration from Western Asia to North Africa, during which the U6 lineage diversified, until the emergence of the present-day U6 African lineages.

Late Quaternary aggradation rates and stratigraphic architecture of the southern Po Plain, Italy

AbstractThePoRiverBasin, where accumulation and preservation of thick sedimentary packages are enhanced by high rates of tectonic subsidence, represents an ideal site to assess the relations between vertical changes in stratigraphic architecture and sediment accumulation rates. Based on a large stratigraphic database, a markedly contrasting stratigraphy ofLatePleistocene andHolocene deposits is reconstructed from the subsurface of the modern alluvial and coastal plains. Laterally extensive fluvial channel bodies and related pedogenically modified muds of latest Pleistocene age are unconformably overlain byHolocene overbank fines, grading seaward into paralic and nearshore facies associations. In the interfluvial areas, a stiff paleosol, dating at about 12.5–10 cal kyBP, marks thePleistocene–Holocene boundary. Across this paleosol, aggradation rates (ARs) from 16 radiocarbon‐dated cores invariably show a sharp increase, from 0.1–0.9 mm year−1to 0.9–2.9 mm year−1. Comparatively lowerPleistocene values are inferred to reflect fluvial activity under a low‐accommodation (lowstand and early transgressive) regime, whereas higherARs during theHolocene are related to increasing accommodation under late transgressive and highstand conditions. Holocene sediment accumulation patterns vary significantly from site to site, and do not exhibit common trends. Very high accumulation rates (20–60 mm year−1) are indicated by fluvial channel or progradational delta facies, suggesting that extremely variable spatial distribution ofHoloceneARs was primarily controlled by autogenic processes, such as fluvial channel avulsion or delta lobe switching. ContrastingARbetween uppermostPleistocene andHolocene deposits also are reported from the interfluves of several coeval, alluvial‐coastal plain systems worldwide, suggesting a key control by allogenic processes. Sediment accumulation curves from adjacent incised valley fills show, instead, variable shapes as a function of the complex mechanisms of valley formation and filling.

Sea surface temperature proxies (alkenones, foraminiferal Mg/Ca, and planktonic foraminiferal assemblage) and their implications in the Okinawa Trough

We reviewed three sea surface temperature (SST) proxies in the Okinawa Trough (OT): alkenones, planktonic foraminiferal Mg/Ca, and planktonic foraminiferal assemblages. The seasonal and vertical distribution patterns of each proxy-related organism in the water column were reviewed to confirm the applicability of each proxy. In addition, current SSTs (Japan Oceanographic Data Center dataset from 1906 to 2003) were compared with core-top sediment temperatures reconstructed using the proxies. Temperatures calculated using the alkenone unsaturation index represent annual mean SSTs, and temperatures calculated using Mg/Ca of Globigerinoides ruber capture summer to autumn (June–November) SSTs. Core-top August SSTs calculated from planktonic foraminiferal assemblages corresponded well with the observed SSTs, but core-top February temperatures were ~3.6 °C warmer than the observed SSTs. SST proxy estimates from marine sediments dating back to the late Holocene (0–3 cal ky BP) and the last glacial maximum (18–21 cal ky BP) were compared. Comparisons between proxy SST estimates show that foraminiferal assemblage-based August SSTs were the warmest. Alkenone-based temperature estimates were lower than Mg/Ca-based temperature estimates, probably because the alkenone-based temperature represents the annual mean temperature, whereas the Mg/Ca-based temperature represents the summer–autumn mean temperature. February assemblage SSTs seem to be greatly affected by the statistical technique and/or database used. These results suggest that seasonality should be considered in past SST reconstruction using alkenone and Mg/Ca in the OT. The planktonic foraminiferal assemblage technique does not appear to be promising with respect to accurately reconstructing past SSTs (especially winter) in the OT. Habitat depth may not be an issue because both alkenone producers and G. ruber live at the upper surface mixed layer in the area. Glacial–interglacial changes in the surface hydrography of the OT reconstructed based on the SST and salinity proxies were also reviewed here. The surface hydrography of the OT has been influenced by changes in the Kuroshio Current and the East Asian monsoon system during the late Quaternary. Comparisons of the hydrography records from the OT with records of stalagmites in China, the Tropical Pacific, and the North Atlantic show that there is a teleconnection between them.

The Oldest Case of Decapitation in the New World (Lapa do Santo, East-Central Brazil).

We present here evidence for an early Holocene case of decapitation in the New World (Burial 26), found in the rock shelter of Lapa do Santo in 2007. Lapa do Santo is an archaeological site located in the Lagoa Santa karst in east-central Brazil with evidence of human occupation dating as far back as 11.7–12.7 cal kyBP (95.4% interval). An ultra-filtered AMS age determination on a fragment of the sphenoid provided an age range of 9.1–9.4 cal kyBP (95.4% interval) for Burial 26. The interment was composed of an articulated cranium, mandible and first six cervical vertebrae. Cut marks with a v-shaped profile were observed in the mandible and sixth cervical vertebra. The right hand was amputated and laid over the left side of the face with distal phalanges pointing to the chin and the left hand was amputated and laid over the right side of the face with distal phalanges pointing to the forehead. Strontium analysis comparing Burial 26’s isotopic signature to other specimens from Lapa do Santo suggests this was a local member of the group. Therefore, we suggest a ritualized decapitation instead of trophy-taking, testifying for the sophistication of mortuary rituals among hunter-gatherers in the Americas during the early Archaic period. In the apparent absence of wealth goods or elaborated architecture, Lapa do Santo’s inhabitants seemed to use the human body to express their cosmological principles regarding death.

Morphodynamics and lake level variations at Paiku Co, southern Tibetan Plateau, China

Proxy records from lakes on the Tibetan Plateau are commonly used to infer monsoon-related climatic changes during the late Quaternary. Specific influences of catchment processes and their interaction with the lake basin are seldom utilized. Based on morphological field investigations, supported by remote sensing analyses in combination with radiocarbon-dated sediment data from lacustrine sequences along paleoshorelines and terraces, we can demonstrate that close relationships exist between glacier dynamics, fluvial–alluvial fan/terrace formation and lake level and lake area changes of Paiku Co, southern Tibet. Our results show that the formation of large-scale, fluvial–alluvial fans (F1) predates the maximum advance of the Xixiabangma glaciers. The latter formed a distinct terminal moraine complex north of the present glaciers during the local LGM (LLGM) at 42–21calky BP. A younger fan generation (F2) developed from the LLGM to the late Holocene, which was accompanied by lake level fluctuations with a generally decreasing trend. The highest morphologically traceable lake level at 4665masl existed prior to 25calky BP and induced a potential overflow to the neighboring Langqiang Co and Pengqu River. A high level also existed during the LLGM, followed by a minor decline until ca. 15calky BP, owing to reduced meltwater discharge under cold and dry climatic conditions. A return to the previous level during the late-glacial/early Holocene period between 11.9 and 9.5calky BP is likely caused by climate warming, increased meltwater discharge, and enhanced Indian Summer Monsoon (ISM) moisture supply. Afterwards, Paiku Co shrank gradually toward its present level, while the youngest fan (F3) generation evolved as individual small-sized bodies under ephemeral discharge conditions from the mid-Holocene to the present.The formation of four terrace levels (T4-1) is likely the result of sequential incision into the fan generations with a mean erosion rate of 50cm/ky, caused by lake level lowering. Tectonic impact cannot be completely ruled out. Since 1976, the glaciers lost ca. 15% in area, accompanied by lake area loss of ~3.7% between 1972 and June 2014. Seasonal lake level variations of about 1–2m in height occur in response to summer monsoon rainfall.Our data show a close interaction between glacial dynamics, fluvial processes, terrace formation, and water budget changes throughout the last 25calky BP in response to the well-known, insolation-driven, ISM-effective moisture supply during the late-glacial and Holocene period. Temperature-driven meltwater dynamics were the controlling factors for variations in water balance of Paiku Co.

Abrupt technological change at the 8.2 ky cal BP climatic event in Central Portugal. The Epipalaeolithic of Pena d’Água Rock-shelter

In central Portugal, the basic structures of the Pleistocene economy, technology and social organization patterns remain fairly similar until the 8.2 ky cal BP climatic event. Their impact has not yet been thoroughly analysed with regard to changes in lithic technology. The Epipaleolithic occupation of Pena d’Água Rock-shelter is dated to ca. 8.19 ky cal BP. In this paper we present a description of its lithic assemblage and put it in context with coeval and later sites of the Middle Tagus, highlighting the observed differences that pre- and post-date this event. Results indicate similarity in raw material acquisition strategies, mainly locally available quartzite cobbles for flake production. After the 8.2 ky event, chert becomes more common, allowing the systematic production of bladelet toolkits with high percentages of geometrics. Reorganized mobility patterns, from forager to logistic, may explain these changes, which remain stable until the Neolithic, ca. 7.4 ky cal BP.

The Holocene environmental changes in southern Indonesia reconstructed from highland caldera lake sediment in Bali Island

Diatom, pollen, geomagnetic and geochemical analyses were carried out on a 3.6 m long sediment core taken from Lake Buyan, a highland caldera lake in central Bali Island, to reconstruct the Holocene climate changes in equatorial southern Indonesia. The core represents ∼8 thousand years sedimentation of organic-diatomaceous lake mud. Constant inclusion of benthic diatom fossils as main components indicated that suspension and inflow of littoral materials were the main sedimentary process. The core contained laminated sediments in two distinct intervals at 6.5–5.0 and 3.6–3.1 cal ky BP, and multi-proxy records showed generally drier climate in these sections especially at 3.6–3.1 cal ky BP. Lake bottom waters were more reducing condition in these laminated periods probably due to increased lake productivity by prolonged dry season and wind mixing. Laminae structures were made up of a layer composed of benthic diatoms and amorphous organic materials, and a layer made by only planktonic diatom fossils, each of which may represent rainy and dry period deposits. Although southern Indonesia shows clear Australian monsoon rainfall seasonality at present, counting of layer numbers showed interannual cycles of laminae formation. Prolonged dry seasons could obscured the rainfall seasonality in these periods, but precise depositional patterns were elusive. Unlaminated sections showed homogeneous sediment mixture of benthic, planktonic diatoms and more volume of terrigenous materials indicating wetter climate and seasonality similar to the present time. This was supported by the higher share of marsh environment pollens reflecting more stable lake level trends. The dry climate from 6.5 cal ky BP was in line with the general perception of stronger ENSO dynamics from the mid Holocene due to weaker than before boreal summer insolation, but the sporadic appearances of dry periods imply the influence of regional climate forcings such as temporal migrations of inter tropical convergence zone (ITCZ). It was, however, possible that temporal shifts of large climate mode occurred in equatorial Pacific and Indian Oceans. Wettest climate was inferred from 3.1 cal ky BP to the present and this might reflect increased importance of Austral hemisphere atmospheric convection and subsequent southerly position of ITCZ in Austral summer time.

Neotropical vegetation responses to Younger Dryas climates as analogs for future climate change scenarios and lessons for conservation

The Younger Dryas (YD) climatic reversal (12.86–11.65 cal ky BP), especially the warming initiated at ∼12.6 cal ky BP, and the associated vegetation changes have been proposed as past analogs to forecast the potential vegetation responses to future global warming. In this paper, we applied this model to highland and midland Neotropical localities. We used pollen analysis of lake sediments to record vegetation responses to YD climatic changes, which are reconstructed from independent paleoclimatic proxies such as the Mg/Ca ratio on foraminiferal tests and Equilibrium Line Altitude (ELA) for paleotemperature, and grayscale density and Titanium content for paleoprecipitation. Paleoclimatic reconstructions at both highlands and midlands showed a clear YD signal with a conspicuous warming extending into the early Holocene. A small percentage of taxa resulted to be sensitive to these YD climate changes. Response lags were negligible at the resolution of the study. However, changes in the sensitive taxa were relevant enough to determine changes in biodiversity and taxonomic composition. Highland vegetation experienced mainly intra-community reorganizations, whereas midland vegetation underwent major changes leading to community substitutions. This was explained in terms of threshold-crossing non-linear responses in which the coupling of climatic and other forcings (fire) was proposed as the main driving mechanism. Paleoecology provides meaningful insights on the responses of highland and midland Neotropical vegetation to the YD climatic reversal. Biotic responses at both individual (species) and collective (assemblage) levels showed patterns and processes of vegetation change useful to understand its ecological dynamics, as well as the mechanisms and external drivers involved. The use of paleoecological methods to document the biotic responses to the YD climate shifts can be useful to help forecasting the potential consequences of future global warming. Due to its quasi-global character, the YD reversal emerges as a well suited candidate for providing useful insights of global scope by analyzing the corresponding biotic responses virtually at any geographical and biological setting.