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This paper examines patterns of human–environmental interactions across northern Asia during the Holocene, in order to summarize current knowledge and identify key areas for future research. To achieve these goals, currently available chronological, cultural, and paleoenvironmental datasets from the east Russian Arctic for the last 10,000 14C years were integrated. Study regions include the Taymyr Peninsula, Lena River basin (except its southern part), northeastern Siberia, and Kamchatka Peninsula. Several broad-scale correlations between climatic fluctuations and cultural responses (e.g., subsistence strategies and occupation densities) were identified; however, these are not straightforward. For example, the increase of occupations during the warm periods in the Early–Middle Holocene are notable while the most pronounced rises coincide with a cooling trend in the Late Holocene. This shows that the human–environmental relationships in the Holocene were not linear; more interdisciplinary research will be needed to construct higher resolution data for understanding prehistoric cultural responses to past environmental changes in the Asian Arctic. [ABSTRACT FROM AUTHOR]

This paper presents 66 radiocarbon (14C) dates obtained at 33 key sites from the Polish part of the European Sand Belt. These calibrated dating results were compared to 34 high-resolution 14C dates obtained from a fluvial-aeolian sediments to identify pedogenic phases from the late Pleniglacial interval to the early Holocene. These identified pedogenic phases were correlated with Greenland ice-core records, revealing high sensitivity of the fluvio-aeolian paleoenvironment to climate changes. Two pedogenic phases were identified from the late Pleniglacial interval (Greenland Stadial GS-2.1b and GS-2.1a), three from the Bølling-Allerød interstadial (Greenland Stadial GI-1), one from the late Allerød–Younger Dryas boundary, and at least one from the Younger Dryas. The ages of these pedogenic phases reveal a distinct delay of 50–100 calendar years after the onset of cool climate conditions during GI-1, reflecting gradual withdrawal of vegetation. Soil horizons from the early Holocene do not show any clear relation with climate change, where breaks in soil formation were caused by local factors such as human activity. [ABSTRACT FROM AUTHOR]

The Sumerian culture flourished within the Tigris and Euphrates rivers floodplains and along their deltaic systems, which ca. 6000 yr were located ~250-260 km inland from the present Persian Gulf. Here, large floodplains and marshes were crossed by an intricate network of channels where several human settlements developed. In this paper, we describe in detail the paleoenvironmental context where the site of Abu Tbeirah (third millennium BC) developed, near the Sumerian capital of Ur. Our interdisciplinary approach, based on remote sensing and the geomorphological study of the area, as well as on sedimentological, paleontological, and paleobotanical analyses of trenches and boreholes deposits, reveals that the site developed along a sinuous channel in a floodplain and marshy environment, where several crevasse splays occurred. This channel was cut off following a flood event. The abandoned portion of the channel was exploited by residents and used as a small river harbor. Our research contributes to better define how the landscape of the site changed over the course of its history and how humans exploited water resources of the area during occupation of the site, a process that was pivotal for the development of the Sumerian culture. [ABSTRACT FROM AUTHOR]

Bats are one of the most abundant and important mammals in ecosystems. However, their fossil record is scarce and fragile, making them difficult to find. Accordingly, there is no record of this group in the volcanic islands of the mid-Atlantic Ocean apart from the Canary Islands. This paper studies the first bat fossil record of the Canary Islands (Spain). The material studied is found within two Quaternary lava tubes, Cueva de los Verdes on Lanzarote and Cueva Roja on the island of El Hierro. The dental and humeral morphology and biometry are analysed and compared with current specimens. Among our results we highlight the first fossil data of two species endemic to the islands of the mid-Atlantic Ocean, Plecotus teneriffae and Pipistrellus maderensis, the former from the Canary Islands and the latter from the Azores, Madeira and the Canary Islands. We also confirm the presence of Pipistrellus kuhlii in the fossil record of the island of Lanzarote. No differences are observed between the dental morphology of the current and the fossil populations of P. maderensis and Pl. teneriffae. In the case of P. kuhlii, the populations of the Canary Islands and the Iberian Peninsula show differences in the paraconule with respect to the populations from central Europe. Palaeoecological studies of these taxa suggest that these islands presented a similar habitat when the sites were formed to the present-day habitat. [ABSTRACT FROM AUTHOR]

This paper analyses a series of high-quality continuous records from southeastern Africa to study the spatiotemporal patterning of Holocene hydroclimatic anomalies in the region. Results indicate dominant frequencies of variability at millennial time scales, and a series of anomalies broadly common to all records. Of particular interest, data from the southern Cape coast exhibit periods of wetter/drier conditions that are out of phase with the sites less than 150 km away in the adjacent interior, but in phase with sites in tropical regions over 1000 km to the northeast. To explain such spatial patterns and gradients, we propose that the Agulhas Current may be a critical vector by which tropical climatic signals are propagated along the littoral zone, exerting a dominant, highly localized influence on near-coastal environmental conditions. Limitations in the data available do not allow for a detailed examination of the climatic dynamics related to these phenomena, but this paper highlights a series of avenues for future research to clarify the spatial extent and stability of the patterns observed. [ABSTRACT FROM AUTHOR]

The 'Wadden Sea Archive of landscape evolution, climate change and settlement history' project (WASA) focuses on the analysis of marine sediment archives from the East Frisian Wadden Sea region. It aims at understanding the formation of palaeolandscapes since the end of the last ice age. One part of the project studies the possible correlation and shift of archaeological settlement patterns, climate change and sea-level rise through time in order to derive archaeological expectancy maps. In this paper we present our findings for a quantifiable set of Stone Age sites in the area of the prehistorical Dornumer tidal basin, discussing them against the background of coastal environmental factors and the applied methodology of our modelling. To enable spatial analysis of these sites, we developed a palaeographic elevation model, which was subsequently flooded at 2000-year intervals between the Boreal and early Subboreal periods. Particular challenges are posed by the dynamics of marine transgression, the related changes in the natural environment and their spatial extent. As a result of our GIS-based approach, the model can be extended geographically and provides a basis for future research. [ABSTRACT FROM AUTHOR]

This paper presents geochemical and grain-size records since the early Holocene in core ECS0702 with a fine chronology frame obtained from the Yangtze River subaqueous delta front. Since ~9500 cal yr BP, the proxy records of chemical weathering from the Yangtze River basin generally exhibit a Holocene optimum in the early Holocene, a weak East Asian summer monsoon (EASM) period during the middle Holocene, and a relatively strong EASM period in the late Holocene. The ~8.2 and ~4.4 cal ka BP cooling events are recorded in core ECS0702. The flooding events reconstructed by the grain-size parameters since the early Holocene suggest that the floods mainly occurred during strong EASM periods and the Yangtze River mouth sandbar caused by the floods mainly formed in the early and late Holocene. The Yangtze River-mouth sandbars since the early Holocene shifted from north to south, affected by tidal currents and the Coriolis force, and more importantly, controlled by the EASM. Our results are of great significance for enriching both the record of Holocene climate change in the Yangtze River basin and knowledge about the formation and evolution progress of the deltas located in monsoon regions. [ABSTRACT FROM AUTHOR]

This paper is a first detailed contribution to the knowledge of serpulid diversity from marine caves of the eastern Mediterranean Sea. A total of 27 taxa were recorded in two submerged caves of Lesvos Island, in the Aegean Sea. A clear trend of variability was observed with serpulid abundance, specifically that of sciaphilic and deep-sea species, increasing inwards while the number of taxa and species diversity did not change significantly across the two caves. In the innermost sectors of the studied caves two types of bioconstructions were observed: (a) ‘coiled doughnuts’ of Protula, recorded for the first time in Mediterranean caves; and (b) ‘biostalactites’ mainly consisting of skeletal metazoans recorded for the first time from the eastern Mediterranean. The results of the present study revealed new faunal elements and type of bioconstructions for the Mediterranean marine caves, showing that several aspects of their communities are still poorly known and deserve to be further investigated. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to evaluate the compatibility between the Holocene relative sea-level (RSL) curves proposed for the Brazilian littoral and mangrove dynamics along a fluvial valley in the state of southern Bahia. This was done integrating geomorphological, sedimentological, palynological, and stable isotopic data from two cores collected at the mouth of the Jucuruçu River and at a site 23 km inland, near the city of Prado, northeastern Brazil. Core PR07, sampled from a fluvial plain at about 4.5±1 m above the RSL, reveals mangrove pollen (5–20%) and estuarine/terrestrial organic matter (δ13C=~–25‰, C/N=7.3–67) between 4.5 m (~7400 cal yr BP) and 1.75 m depth (~5350 cal yr BP). Core PR11, sampled from a mangrove tidal flat, also revealed mangrove pollen taxa (5-28%) since 660 cal yr BP. Core PR07 indicated absence of mangrove pollen and increase of sedimentary organic matter sourced from terrestrial C3 plants (δ13C=~–27‰, C/N=22–159) during the last 5350 cal yr BP. Probably, the changes in vegetation and sedimentary organic matter identified in core PR07 were caused by the combined effects of the RSL fluctuations, with a highstand at about 5350 cal yr BP of 2.7±1.35 m, and changes in fluvial discharge. [ABSTRACT FROM AUTHOR]

This paper presents the first successful methods for accelerator mass spectrometry (AMS) dating of asphalt-impregnated insect chitin from the Rancho La Brea Tar Pits in southern California. A persistent problem with stratigraphic correlation at this site is that asphalt flows are characteristically intermittent and are really discontinuous, which can result in mixing fossils of quite different ages. Direct 14C dating of specimens circumvents this difficulty but requires a pretreatment method that can produce dates from relatively small samples (<10 mg) of insect cuticle, while successfully removing residual asphalt and sample preparation solvents as well as soil carbon contamination. 14C dating accuracy was verified by comparing dates on insect chitin with ages for seeds and twigs compacted during a rapid entrapment event within a separately dated skull of the Western Camel, Camelops hesternus Leidy. All dates fell within a relatively narrow range of ~40,000–44,000 14C yr BP, suggesting that such methods can be used with confidence on other insect material from this site. Insects are often superior paleoenvironmental indicators for establishing precise data points for climate fluctuations. This is because their lifecycles and present-day climate-restricted geographic distributions are well documented, and unlike migrating mammals and birds, insects offer crucial information about the local environment. Our results are therefore potentially significant for studies of paleoecological and paleoclimatic change within the Los Angeles Basin and coastal southern California, as well as reconstruction of entrapment events at Rancho La Brea. [ABSTRACT FROM AUTHOR]

Here we report a new find of abundant woody debris and cones in stratum of two sections located to the east of the Qinghai Lake basin in China. Analysis of the anatomical structure of the wood and cones confirmed that they are Picea crassifolia Kom. The results of accelerator mass spectrometry 14C dating indicate that the buried Qinghai spruce grew during 9.7–4.2 ka, and the ages of the large trunks or branches are mainly concentrated within the interval 7.5–6.5 ka. This finding gives direct evidence at the species level about the presence of coniferous forest in the early–middle Holocene in Qinghai lake basin. In addition, the buried cones suggest that the early-middle Holocene environment was suitable for the propagation of Picea crassifolia Kom. The variations in the occurrence of Qinghai spruce forest in the Holocene probably reflect changes in humidity/moisture. The humid early-middle Holocene was suitable for the growth and reproduction of Qinghai spruce forest, while a shift toward an increasingly arid climate during the late Holocene resulted in the disappearance of Picea crassifolia Kom. from the Qinghai Lake basin, although human activities may also have contributed to the environmental change. [ABSTRACT FROM AUTHOR]

As an isolated island group lying off the NW European mainland which was uninhabited until the mid-first millennium AD, the Faroes offer a unique opportunity to study natural processes of Holocene ecosystem development in a region where anthropogenic activity is usually a complicating factor. In this paper new radiocarbon dates and pollen-analytical data from the island of Sandoy, in the centre of the Faroes archipelago, are presented. Together with existing pollen and plant macrofossil records, these data allow a reconstruction of patterns of Holocene vegetational and edaphic change. Basal peat dates indicate that large areas of blanket mire were established long before the first human settlement, demonstrating conclusively that human impact is not necessary for the development of such ecosystems. The timing of the initiation of the blanket peats varies markedly, both across the Faroes as a whole and at a landscape scale, with dates distributed evenly over 9000 years. This suggests that, in the Faroes at least, pedogenesis was more important than climatic change in determining the timing of the spread of blanket peat systems. [ABSTRACT FROM PUBLISHER]

We compare radiocarbon (14C) ages of coexisting planktonic foraminifera species from sediment cores VM12-107 and KNR166-2-26JPC from the Equatorial Atlantic Ocean for three time periods (Holocene, Heinrich Stadial 1, last glacial maximum). We find a maximum inter-species difference of 1200 14C yr. On average, the 14C ages deviate by ∼300 yr between Globigerinoides ruber and other species. In most cases, this exceeds the analytical uncertainty range of the measurements and thus renders the choice of species for generating age models as important as sample weight. While modern stratified water-column profiles imply an increase in 14C ages with water depth, we observe an expected parallel increase of 14C ages and δ18O only at VM12-107. The mismatch between 14C ages and δ18O at KNR166-2-26JPC likely results from the effects of bioturbation and the hydrographic setting. The largest difference in 14C ages between mixed-layer versus thermocline-calcifying planktonic foraminifera are observed during Heinrich Stadial 1 despite a decrease in upper-ocean stratification at that time. This difference is likely the result of inconsistent increases in 14C reservoir ages during times of reduced overturning circulation masking the potential of 14C ages of coexisting planktonic foraminifera to reflect the density stratification of the water column. [ABSTRACT FROM AUTHOR]

The timeframes of Holocene anthropogenic dune remobilization in Central Europe remain less studied compared to those of Late Glacial climatically controlled dune formation. The present contribution aims to reinforce existing knowledge on the chronology of Late Glacial–Holocene dune activity and stability, as well as to reveal the scale of human impact on dune remobilization. Accelerator mass spectrometry radiocarbon (AMS 14C) dating and calibration of the results are reported from paleosol horizons buried in inland dune deposits that occur in Central and Eastern Poland. Twenty-three new dates are based on charcoal samples collected at 13 sites. From each of the investigated sites, at least one AD date is obtained, indicating that buried paleosols of such young age are far more widespread in Polish dunes than reflected in previous studies. The widespread preservation of these paleosols under cover of aeolian sand reflects the extent of the anthropogenic dune formation phase that peaked during the Medieval and Early Modern periods. [ABSTRACT FROM AUTHOR]

The fluvial geomorphology and stratigraphy on the middle Snake River at Bancroft Springs, Idaho, provide evidence for numerous episodes of Snake River aggradation and incision since the Bonneville Flood at ca. 18 ka. A suite of seven terraces ranging from 20–1 m above modern bankfull elevation records multiple cut-and-fill cycles during the latest Pleistocene and Holocene in response to local base-level controls, variations in sediment supply, and hydroclimate change. Radiocarbon and luminescence dating show that the ages of fluvial aggradation generally coincide with increased sediment supply and likely wetter hydroclimate during onset of the Younger Dryas stadial (ca. 13.2 ka), deglaciation and termination of the Younger Dryas stadial (ca. 11.3 ka), Early Holocene cooling (ca. 8.8 ka), and Neoglacial (ca. 4.5, 2.9, 1.1 ka). Six intervening periods of incision and channel stability may also reflect either reduced sediment supply, drier hydroclimate, or both. The terrace chronology can be correlated to a variety of local and regional paleoclimate proxy records and corresponds well with periods of continental- and global-scale rapid climate change during the Holocene. The fluvial record demonstrates the geomorphic response and sensitivity of large river systems to changes in hydroclimate variability, which has important implications for inferring paleoenvironmental conditions in the region. [ABSTRACT FROM AUTHOR]

Continuous records of sediment yield spanning from the late glacial through the Holocene to the present day provide an important opportunity to investigate landscape evolution over various timescales in response to a variety of natural and anthropogenic forcing mechanisms. This study investigates variations in sediment yield and landscape evolution in the 768 km2 watershed of Ossipee Lake, New Hampshire, USA. We pair subbottom sonar observations with analyses of lacustrine sediment cores to interpret a 12,000+ yr record of lake sedimentation in terms of changes in sediment yield and landscape evolution. Our results indicate high rates of sediment redistribution following deglaciation at ∼14,500 to ∼12,000 cal yr BP, followed by a period of gradually decreasing sediment yield until ∼9000 cal yr BP, marking the termination of the most intense period of paraglacial landscape adjustment. From 9000 cal yr BP to 1850 CE, sediment yield is highly variable and reveals a slightly increasing trend that we attribute to a dominant hydroclimatic control on erosion driven by increasing effective precipitation in the region throughout the Holocene. Despite evidence for a highly dynamic landscape and an abundance of unconsolidated glacigenic surface deposits throughout the watershed, we interpret a modest erosional impact from anthropogenic land use. [ABSTRACT FROM AUTHOR]

Paleoecological and modern studies at Priyatnoye Lake, which is located within an intermontane depression in the interior of northeastern Siberia, indicate a similar paleovegetation record as has been documented for nearby mountain valleys, but a history of basin stability and instability that is uncharacteristic of the valley lakes. Analyses of a 385-cm-long core from the western basin of Priyatnoye Lake shows that sediment accumulation began in late Marine Oxygen Isotope Stage 3 (MIS 3), followed by a hiatus during MIS 2, and then continuous accumulation over the past ca. 14,000 cal yr BP. The eastern basin of the lake has a sediment thickness of ∼35 cm, suggesting that it intermittently contained water and/or is younger than the western basin. A drop in lake levels between AD 2005 and AD 2009 resulted in the formation of two distinct lakes. This change was caused by the melting of underlying ice wedges and the formation of sinkholes through which the lake water drained. Although the northern coastal lowlands have been the geographic focus of permafrost global warming research, the Priyatnoye study draws attention to the intermontane depressions in northeastern Siberia. While less extensive, these depressions contain organic-rich deposits, are underlain by permafrost, and have the potential to affect future carbon budgets as global temperatures rise and permafrost melts. [ABSTRACT FROM AUTHOR]

Holocene sediments at Emerald Lake in central Utah (3090 m asl) document the paleohydroclimatic history of the western Upper Colorado River headwater region. Multi-proxy analyses of sediment composition, mineralogy, and stable isotopes of carbonate (δ18O and δ13C) show changes in effective moisture for the past ca. 10,000 years at millennial to decadal timescales. Emerald Lake originated as a shallow, closedbasin cirque pond during the Early Holocene. By ca. 7000 cal yr BP, higher lake levels and carbonate δ18O values indicate rising effective moisture and higher proportions of summer precipitation continued at least until ca. 5500 cal yr BP when a landslide entered the lake margin. Between ca. 4500 and 2400 cal yr BP dry conditions at Emerald Lake envelop the timing of the ‘Late Holocene Dry Period’ identified at lower elevations. For the past ca. 2500 years, Emerald Lake δ18O values were relatively low, indicating wetter conditions and higher snow input (compared to rain), except for dry periods at ca. 2000 cal yr BP and during the Medieval Climate Anomaly at ca. 1000 and ca. 500 cal yr BP. Results provide a long-term perspective on precipitation extremes that influence regional water supplies from a snow-dominated catchment typical of the predominant source region for the Upper Colorado River. [ABSTRACT FROM AUTHOR]

Postglacial changes in sea-surface conditions, including sea-ice cover, summer temperature, salinity, and productivity were reconstructed from the analyses of dinocyst assemblages in core S2528 collected in the northwestern Barents Sea. The results show glaciomarine-type conditions until about 11,300 ± 300 cal yr BP and limited influence of Atlantic water at the surface into the Barents Sea possibly due to the proximity of the Svalbard-Barents Sea ice sheet. This was followed by a transitional period generally characterized by cold conditions with dense sea-ice cover and low-salinity pulses likely related to episodic freshwater or meltwater discharge, which lasted until 8700 ± 700 cal yr BP. The onset of "interglacial" conditions in surface waters was marked by a major change in dinocyst assemblages, from dominant heterotrophic to dominant phototrophic taxa. Until 4100 ± 150 cal yr BP, however, sea-surface conditions remained cold, while sea-surface salinity and sea-ice cover recorded large amplitude variations. By -4000 cal yr BP optimum sea-surface temperature of up to 4°C in summer and maximum salinity of -34 psu suggest enhanced influence of Atlantic water, and productivity reached up to 150 gC/m²/yr. After 2200 ± 1300 cal yr BP, a distinct cooling trend accompanied by sea-ice spreading characterized surfacewaters. Hence, during the Holocene, with exception of an interval spanning about 4000 to 2000 cal yr BP, the northern Barents Sea experienced harsh environments, relatively low productivity, and unstable conditions probably unsuitable for human settlements. [ABSTRACT FROM AUTHOR]

The North Sea is considered a unique heritage site that yielded a huge amount of zoological and archaeological data. More than 200 palaeozoological and archaeological fossil bone samples from the North Sea bed are dated by 14C. About 2/3 of these dated bones are Pleistocene in age; the majority of the bones are from extinct species (in particular woolly mammoth); about 1/3 of the sample date to the Holocene. The presented dataset is important in its kind, but interpretation is limited because of a lack of context of the finds. The stable isotopes (13C, 15N) of the dated samples provide additional information on palaeoenvironmental conditions and dietary habits in the past. We present primarily a Groningen list of data; a few fossils dated in other laboratories are included for completeness. [ABSTRACT FROM AUTHOR]

Despite extensive paleoenvironmental research on the postglacial history of the Kenai Peninsula, Alaska, uncertainties remain regarding the region's deglaciation, vegetation development, and past hydroclimate. To elucidate this complex environmental history, we present new proxy datasets from Hidden and Kelly lakes, located in the eastern Kenai lowlands at the foot of the Kenai Mountains, including sedimentological properties (magnetic susceptibility, organic matter, grain size, and biogenic silica), pollen and macrofossils, diatom assemblages, and diatom oxygen isotopes. We use a simple hydrologic and isotope mass balance model to constrain interpretations of the diatom oxygen isotope data. Results reveal that glacier ice retreated from Hidden Lake's headwaters by ca. 13.1 cal ka BP, and that groundwater was an important component of Kelly Lake's hydrologic budget in the Early Holocene. As the forest developed and the climate became wetter in the Middle to Late Holocene, Kelly Lake reached or exceeded its modern level. In the last ca. 75 years, rising temperature caused rapid changes in biogenic silica content and diatom oxygen isotope values. Our findings demonstrate the utility of mass balance modeling to constrain interpretations of paleolimnologic oxygen isotope data, and that groundwater can exert a strong influence on lake water isotopes, potentially confounding interpretations of regional climate. [ABSTRACT FROM AUTHOR]

Understanding the recent events marking the late Quaternary history of the Po Plain (N-Italy) is of overriding importance to decipher the record of depositional versus erosional phases, and their interplay with climatic, tectonic, and human forcing. We reconstructed the structural setting and chronostratigraphy of a Holocene succession crosscut by a thrust fault located south of Montodine (Cremona, Italy) within the Po Plain. The fault shows a maximum displacement up to one meter. Radiocarbon dating fixes a minimum age of 11.9 cal ka BP for the postglacial river entrenchment and constrains the fault movement age between 5.9 and 3.4 cal ka BP. Undeformed Late Medieval coarse gravels cover the faulted succession. Due to the outcrop position, lying above the buried frontal thrusts of the Southern Alps and North Apennines, we propose that faulting results from secondary surface effects induced by seismic shaking. We discuss two main mechanisms, both related to lateral spreading, that can result in the formation of reverse faults close to the surface. The Soncino area, recording one of the strongest historical earthquakes of the central Po Plain (1802), is considered as a possible source for seismic shaking. The results of this study are a contribution for the assessment of the potential seismic hazard in one of the most populated regions of Europe. [ABSTRACT FROM AUTHOR]

Greenock Swamp wetland complex is one of few remaining natural wetlands in the Great Lakes region and, at 89 km2 in areal extent, is currently the largest hardwood swamp in southern Ontario, Canada. We present here pollen and sediment records from a kettle hole (Schmidt Lake) and adjacent Thuja occidentalis swamp to reconstruct regional paleoclimate and vegetation history, and to assess the timing and development of the swamp ecosystem and associated carbon stocks. Pollen-inferred paleoclimate reconstructions show the expected warming in the Early Holocene, and indicate the Mid-Holocene initiation of lake-effect snow. This enhanced snowfall may have maintained high water tables in the adjacent wetland since ca. 8300 years ago, promoting the establishment of a swamp dominated by Thuja occidentalis. Carbon accumulation rates in a >2-m-long peat core collected from a Thuja occidentalis stand adjacent to Schmidt Lake are 30-40 g C/m2/yr, which is higher than the average of northern high-latitude peatlands. Using topographic and hydrological parameters, we estimated that mean swamp peat thicknesses could exceed 2m. Thus, this study encourages future investigations on temperate swamps from the perspective of hitherto underestimated Holocene carbon sinks and shows the importance of regional hydroclimate in supporting swamp ecosystems. [ABSTRACT FROM AUTHOR]

Analysis of patterns of faulting and hydrogeology, stratigraphic and sedimentologic studies, and luminescence dating of aeolian deposits in China Lake basin provide new perspectives on the origins and development of Late Holocene dunes and sand ramps in the seismically active Indian Wells Valley of eastern California. Aeolian dune and sand sheet deposits were sourced from alluvial material derived from granitic rocks of the south-eastern Sierra Nevada and are concentrated in areas with sand-stabilizing phreatophyte vegetation influenced by high groundwater levels along the active oblique-normal Little Lake and Paxton Ranch faults, which locally form barriers to groundwater flow. Three episodes of sand accumulation are recognized (2.1 ± 0.1 to 2.0 ± 0.1 ka, 1.8 ± 0.2 to 1.6 ± 0.2 ka, and 1.2 ± 0.1 to 0.9 ± 0.1 ka) during conditions in which sediment supplied to the basin during periods of enhanced rainfall and runoff was subsequently reworked by wind into dunes and sand ramps at the transition to more arid periods. Understanding the role tectonics plays in influencing the hydrogeology of seismically active lake basins provides insights to accurately interpret landscape evolution and any inferences made on past hydroclimate variability in a region. [ABSTRACT FROM AUTHOR]

In the Cordillera Darwin, southernmost South America, we used 10Be and 14C dating, dendrochronology, and historical observations to reconstruct the glacial history of the Dalla Vedova valley from deglacial time to the present. After deglacial recession into northeastern Darwin and Dalla Vedova, by ~16 ka, evidence indicates a glacial advance at ~13 ka coeval with the Antarctic Cold Reversal. The next robustly dated glacial expansion occurred at 870 ± 60 calendar yr ago (approximately AD 1150), followed by less-extensive dendrochronologically constrained advances from shortly before AD 1836 to the mid-twentieth century. Our record is consistent with most studies within the Cordillera Darwin that show that the Holocene glacial maximum occurred during the last millennium. This pattern contrasts with the extensive early- and mid-Holocene glacier expansions farther north in Patagonia; furthermore, an advance at 870 ± 60 yr ago may suggest out-of-phase glacial advances occurred within the Cordillera Darwin relative to Patagonia. We speculate that a southward shift of westerlies and associated climate regimes toward the southernmost tip of the continent, about 900–800 yr ago, provides a mechanism by which some glaciers advanced in the Cordillera Darwin during what is generally considered a warm and dry period to the north in Patagonia. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents new evidence from the Dhamar highlands, Yemen, of paleohydrologic response to fluctuations in Holocene climate. Stratigraphic, geochemical, and chronological analyses of highland peat and lacustrine deposits contribute to knowledge of the timing of early Holocene moisture changes on the Arabian Peninsula, providing a backdrop to understanding early cultural development in the Arabian highlands. The location of the Dhamar highlands, characterized by intermontane valleys surrounded by the highest mountains on the Arabian Peninsula and adjacent to the Indian Ocean is ideal for examining the influence of the Indian Ocean Monsoon (IOM) on the moisture history of this region. Fluctuations in the lacustrine and paleosol records of the Dhamar highlands reflect both local changes in paleohydrology and regional influences on the Holocene paleoclimatic conditions in southwest Arabia. In addition, a peat deposit with a radiocarbon age of 10,253 – 10,560 cal yr BP documents some of the earliest Holocene high moisture conditions on the Arabian Peninsula. [Copyright &y& Elsevier]

Abstract: This paper describes palynological evidence for what appears to be comparatively large-scale human impact in the catchment of the Sungai Niah in the wet tropical lowland swamp forests of Sarawak, Malaysian Borneo close to the Great Cave of Niah. Pollen associated with cleared landscapes and rice cultivation is evident in the sedimentary record from before 6000 cal yr B.P. Human activity seems to have been associated with changes in sedimentary regime, with peat-dominated environments being replaced diachronously by clay-dominated deposition. This may reflect anthropogenic soil erosion in the catchment of the Sungai Niah. [Copyright &y& Elsevier]

Raised beach ridges on Livingston Island of the South Shetland Islands display variations in both quantity and source of ice rafted detritus (IRD) received over time. Whereas the modem beach exhibits little IRD, all of which is of local origin, the next highest beach (∼250 14C yr BP) has large amounts, some of which comes from as far away as the Antarctic Peninsula. Significant quantities of IRD also were deposited ∼1750 14C yr BP. Both time periods coincide with generally cooler regional conditions and, at least in the case of the ∼250 yr old beach, local glacial advance. We suggest that the increases in ice rafting may reflect periods of greater glacial activity, altered ocean circulation, and/or greater iceberg preservation during the late Holocene. Limited IRD and lack of far-travelled erratics on the modem beach are both consistent with the ongoing warming trend in the Antarctic Peninsula region. [ABSTRACT FROM AUTHOR]

Paleoperspectives of climate provide important information for understanding future climate, particularly in arid regions such as California, where water availability is uncertain from year to year. Here, we present a record from Barley Lake, California, focusing on the interval spanning the Younger Dryas (YD) to the early Holocene (EH), a period of acute and rapid global climate change. Twelve radiocarbon dates constrain the timing between 12.9 and 8.1 ka. We combine a variety of sediment analyses to infer changes in lake productivity, relative lake level, and runoff dynamics. In general, the lake is characterized by two states separated by a <200-year transition: (1) a variably deep, lower-productivity YD lake; and (2) a two-part variably shallow, higher-productivity EH lake. Inferred EH winter-precipitation runoff reveals dynamic multidecadal-to-centennial-scale variability, in agreement with the EH lake-level data. The Barley Lake archive captures both hemispheric and regional signals of climate change across the transition, suggesting a role for both ocean-atmosphere and insolation forcing. Our paleoperspective emphasizes California's sensitivity to climate change and how that change can generate abrupt shifts in limnological regimes. [ABSTRACT FROM AUTHOR]

This paper reexamines the stratigraphy, sources, and paleoclimatic significance of Holocene Bignell Loess in the central Great Plains. A broadly similar sequence of loess depositional units and paleosols was observed in thick Bignell Loess sections up to 300 km apart, suggesting that these sections record major regional changes in the balance between dust deposition and pedogenesis. New optical ages, together with previously reported radiocarbon ages, indicate Bignell Loess deposition began 9000–11,000 yr ago and continued into the late Holocene; some Bignell Loess is <1000 yr old. There is little evidence that Holocene Loess was derived from flood plain sources, as previously proposed. Instead, thick Bignell Loess occurs mainly near the downwind margins of inactive dune fields, particularly atop escarpments facing the dunes. Thus, the immediate loess source was dust produced when the dunes were active. Previous work indicates that widespread episodes of dune activity are likely to have resulted from drier-than-present climatic conditions. The regionally coherent stratigraphy of Bignell Loess can be interpreted as a near-continuous record of climatically driven variation in dune field activity throughout the Holocene. [Copyright &y& Elsevier]

When dealing with stratigraphic successions in marginal basin settings, the geological record is often fragmented due to erosion and reworking processes. The North Sea Basin is an example: it has a fragmented Quaternary record; in particular, Middle Pleistocene intervals are poorly known. As a result, we have little insight into climate, marine environmental conditions and biodiversity in this period. Here we describe and discuss a succession of three interglacial marine mollusc-bearing intervals in a borehole from Ameland in the northern Netherlands (borehole B01H0189 near Hollum). These intervals are attributed to marine isotope stages MIS7, MIS5e and MIS1. The Holocene Celtic type of faunas (interval 0–26.24 m below surface (b.s.)) and Eemian Lusitanian type of faunas (26.24–30.40 m b.s.) are well-known from previous research. The newly reported MIS7 Oostermeer fauna (32.80–39.00 m b.s.) represents mostly full marine settings between storm wave base and fair-weather wave base. In composition and diversity, the MIS7 and MIS1 faunas strongly resemble and differ from the MIS5e fauna. This is the first well-documented record of three stacked marine interglacial assemblages from the southern North Sea Basin at one location. This new record enables us to make complete marine faunal characterisations of successive interglacial periods. Key implications for southern North Sea stratigraphy and palaeogeography are the resemblance of marine faunas and conditions in MIS7 and MIS1, the presence of a relatively warm latest MIS6 freshwater interval and confirmation and characterisation of the warm Eemian interval north of the classical type area. [ABSTRACT FROM AUTHOR]

Debris-covered glaciers constitute a large part of the world's cryosphere. However, little is known about their long-term response to multi-millennial climate variability, in particular in the Southern Hemisphere. Here, we provide first insights into the response of a debris-covered glacier to multi-millennial climate variability in the sub-Antarctic Kerguelen Archipelago, which can be compared to that of recently investigated debris-free glaciers. We focus on the Gentil Glacier and present 13 new 36Cl cosmic-ray exposure ages from moraine boulders. The Gentil Glacier experienced at least two glacial advances: the first one during the Late Glacial (19.0–11.6 ka) at ~14.3 ka and the second one during the Late Holocene at ~2.6 ka. Both debris-covered and debris-free glaciers advanced broadly synchronously during the Late Glacial, most probably during the Antarctic Cold Reversal event (14.5–12.9 ka). This suggests that both glacier types at Kerguelen were sensitive to abrupt temperature changes recorded in Antarctic ice cores, associated with increased moisture. However, during the Late Holocene, the advance at ~2.6 ka was not observed in other glaciers and seems to be an original feature of the debris-covered Gentil Glacier, related to either distinct dynamics or to distinct sensitivity to precipitation changes. [ABSTRACT FROM AUTHOR]

The variability of the East Asian monsoon (EAM) during the Holocene exhibits significant regional response, and its evolution needs further discussion. A well-dated, high-resolution sea-surface temperature record based on long-chain unsaturated alkenones, grain-size data, and clay mineral assemblages from the South Yellow Sea sediment is presented to investigate the sedimentary provenance and reconstruct the EAM over the past 9.5 ka. The results show that the sediments are most likely supplied by the Huanghe. The evolution of the East Asian summer monsoon (EASM) can be divided into three periods: strong and relatively stable conditions during 9.5–7.0 ka, weakened conditions during 7.0–1.5 ka, and strengthened conditions during 1.5–0 ka. The East Asian winter monsoon (EAWM) has experienced five periods: weakened conditions during 9.5–6.7 ka, weak and relatively stable conditions during 6.7–5.6 ka, strong and relatively stable conditions during 5.6–2.6 ka, strengthened conditions during 2.6–1.5 ka, and weak and stable conditions during 1.5–0 ka. Moreover, in-phase correlation was found between the EAWM and EASM at the orbital time scale in response to orbital-driven solar insolation, but out-of-phase correlation at a centennial time scale is predominantly associated with solar activity. [ABSTRACT FROM AUTHOR]

The East Asian monsoon (EAM) has experienced significant changes over the past 10,000 years that influenced East Asian agricultural development. However, the magnitude and extent of the EAM precipitation fluctuations at 6 ka remain unresolved, owing to uncertainty in individual lake records and substantial variations in the expansion limits in simulations of the mid-Holocene EAM precipitation. Here we present an approach based on multiple lake-level records using the "1D lake level—2D lake area—3D catchment hydrology" model to reconstruct the precipitation patterns in northern China, and to further quantify the extent of the EAM precipitation expansion in the mid-Holocene relative to today. The precipitation reconstructions suggest an ~550–1100 km northward expansion and an ~530–840 km westward migration of the EAM at 6 ka. At that time, the EAM precipitation domain covered over 6 million square kilometers. Thus, this approach mitigates the uncertainty and arbitrariness of reconstructions of the limit of the EAM precipitation fields and provides a benchmark for future climate modeling studies. [ABSTRACT FROM AUTHOR]

In contrast to temperate regions, relationships between basin characteristics (e.g., type/size) and fossil pollen archives have received little attention in Amazonia. Here, we compare fossil pollen records of a small palm swamp (Cuatro Vientos; CV) and a nearby large lake (Laguna Chaplin, LCH) in Bolivian Amazonia, demonstrating that palm swamps can yield Quaternary pollen archives recording the history of terrestrial vegetation beyond the basin margin, rather than merely a history of localized swamp vegetation dynamics. The pollen assemblages from these two contrasting basins display remarkable agreement throughout their late Quaternary history, indicating past drier climates supported savanna landscape during the last glacial maximum (LGM; 24,000–18,000 cal yr BP) and savanna/semideciduous forest mosaic during the middle Holocene (7000-4750 cal yr BP) at both regional (inferred from LCH) and local (inferred from CV) spatial scales. Additionally, the local-scale catchment of CV and the basin's proximity to the riverine forests of the Río Paraguá enables exploration of the extent of gallery/riverine forests during the LGM and middle Holocene. We show that, between 24,000–4000 cal yr BP, riverine/gallery rainforests were substantially reduced compared with present, challenging the hypothesis that gallery rainforests were important refugia for rainforest species during the drier LGM and middle Holocene. [ABSTRACT FROM AUTHOR]

A physical oceanographic, geophysical and marine geological survey of Edward VIII Gulf, Kemp Coast, collected data from conductivity–temperature–depth casts, multi-beam bathymetric swath mapping and 3.5 kHz sub-bottom surveying. Modified circumpolar deep water (mCDW) is observed in Edward VIII Gulf, as well as notable bathymetric features including mega-scale glacial lineations and a 1750 m-deep trough. Sedimentological, geochemical, rock-magnetic and micropalaeontological analysis of two kasten cores document regional palaeoclimate and palaeo-oceanographic conditions over the past 8000 years, with a warm period occurring from c. 8 to 4 ka and a shift to cooler conditions beginning at c. 4 ka and persisting until at least 0.9 ka. Sediment packages > 40 m thick within deep troughs in Edward VIII Gulf present potential targets for higher-resolution Holocene and deglacial climate studies. Despite the presence of mCDW on the shelf, inland bed topography consisting of highland terrain suggests the likelihood of relative stability of this sector of the East Antarctic Ice Sheet. [ABSTRACT FROM AUTHOR]

Some lateral moraines contain a rich record of Holocene glacial expansion. Previous workers have used such evidence to document glacial fluctuations in western Canada, Alaska, and the U.S. Pacific Northwest, but similar studies in Patagonia are uncommon. Here we report on the late Holocene behavior of Stoppani Glacier, a 75 km2 glacier sourced in the Cordillera Darwin, southernmost Patagonia. Based on radiocarbon-dated wood and organic material contained in the glacier's northeast lateral moraine, we infer that Stoppani Glacier advanced shortly before 3.8–3.6, at 3.2–2.8, 2.3–2.1, and 0.3–0.2, and possibly sometime before 1.4–1.3 and 0.8–0.7 cal ka BP. These advances culminated at 0.3–0.2 cal ka BP, when the glacier constructed a prominent end moraine, marking its greatest extent of the past 4000 years. Although the timing of several of the advances overlap with the age range of glacial expansion recognized elsewhere in Patagonia, some do not. Asynchronous behavior observed in the glacial record may arise from the type of evidence (e.g., lateral stratigraphy vs. end moraine) used to document glacial fluctuations or variations in climate or glacial response times. A significant difference between the Stoppani record and some other Patagonian records is that the former indicates general expansion of ice over the last 4000 years, whereas the latter indicate a net decrease in extent over that period. [ABSTRACT FROM AUTHOR]

The directions of strong winds are important for the distribution of marine salt spray, rock weathering, lake chemistry and the distribution of vegetation in Bunger Hills, a coastal ice-free oasis in East Antarctica. Present-day strong winds (> 10 m s−1) dominantly blow from 118 ± 21 degrees true (°T; ± 1 SD). Orientated tafoni (weathering pits) might form in bedrock surfaces by salt and ice crystallization, thermal stress and saltating sand particles, recording the orientation of a strongly directional wind field since the last deglaciation, which commenced > 30 000 years ago. The orientations of these tafoni, at 101 ± 18°T for 686 measurements at 28 sites, are indistinguishable from the direction of modern-day strong winds (> 10 m s−1), indicating that the orientation of the slope of the ice sheet has been stable throughout the last 10 000 years during the Holocene. [ABSTRACT FROM AUTHOR]

Pollen, plant macrofossils, and sedimentary analyses from archaeological deposits at North Creek Shelter (NCS) on the Colorado Plateau provide data on vegetation and climate change during the Holocene. From 11,300–10,200 cal yr BP, NCS was embedded in a mixed conifer forest of cool-adapted species (e.g., Abies , Pseudotsuga menziesii , and Pinus ponderosa) with an Artemisia understory. During this interval, NCS pollen corresponds to modern pollen from Picea–Abies forests that reside 950 m higher in elevation. Rapid deposition rates of NCS sediments indicate that climatic conditions during the Early Holocene were more mesic than today, with increased precipitation. The onset of warmer conditions at NCS began at 10,200 cal yr BP, and pollen and plant macrofossils indicate that a semiarid woodland and scrub mosaic dominated by Pinus edulis , Juniperus osteosperma , and Amaranthaceae surrounded NCS by 9300 cal yr BP. This is corroborated by fossil pollen that is similar to modern pollen from P. edulis – J. osteosperma woodlands and Amaranthaceae scrub that currently surround NCS. Sedimentary analyses suggest that during this time, accumulation rates were very low due to low precipitation and a drier climate overall. Migration of P. edulis into southern Utah is directly dated to 8100 cal yr BP, thus confirming recently proposed patterns of northward expansion. [ABSTRACT FROM AUTHOR]

The sedimentological and geochemical characteristics of sediments from Lake Szurpiły (northeastern Poland) can be used as a record of mass movement and climate dynamics since the Allerød. Late-glacial sediments suggest enhanced runoff conditions in the catchment after the retreat of the Scandinavian Ice Sheet, while Holocene varved sediments are interrupted by mass-movement deposits (MMDs). We identified 85 thin (<10 cm) MMDs (type 1) that consist of autochthonous material and frequently occur during the Atlantic period. Mobilization of littoral zone and slope sediments caused redeposition in the deepest part of the lake and was likely related to climatic conditions. In contrasting, one sedimentary unit (>1-m-thick MMD type 2) consists of auto- and allochthonous material and represents multistage processes, including erosion and deformation of underlying varved sediments, rapid deposition of clastic material, and redeposition of previously eroded varved sediments. Seismic activity or permafrost degradation was responsible for the deposition of MMD type 2. Furthermore, varve-thickness variability suggests Gleissberg and Suess solar cycles before 850 BC, when human impact was limited. Additionally, 22 and 11 yr sunspot cycles are recognized in light/dark laminae-thickness ratios and reflect influences of solar irradiance on lacustrine productivity. [ABSTRACT FROM AUTHOR]

Wildfires are sensitive to climate change, but their response to changes in temperature and precipitation on long timescales is still disputed. In this study, we present a ~9.4 ka black carbon mass sedimentation rate (BCMSR) record from Lake Ximenglongtan (XMLT), southwestern China, to elucidate the Holocene fire regime and its linkages to climatic conditions. The results indicate that the regional fire activity was low during the early Holocene (before 7.6 cal ka BP), increased notably at 7.6 cal ka BP, and continued to increase gradually during the mid- to late Holocene until 2.2 ka. The episodes of higher fire occurrence reflected by higher BCMSR over the last 2.2 ka might be more likely related to the intensified human activities. The cool and humid climate during the early Holocene limited the spread of fire, while warming and drying at ~7.6 cal ka BP triggered higher fire occurrence. Instead of temperature, changes in precipitation dominated fire regime variation during the mid- to late Holocene. On millennial timescales, we suggest that Holocene fire variability has been predominantly controlled by the combined effects of Northern Hemisphere (NH) summer and winter insolation that influenced monsoonal precipitation and fire season temperature, respectively. Indian Ocean Dipole (IOD) events may also have affected fire incidence through influencing monsoon intensity. [ABSTRACT FROM AUTHOR]

Stratigraphic records extending to Marine Oxygen Isotope Stage (MIS) 3 (57,000–29,000 cal yr BP) or older in Beringia are extremely rare. Three stratigraphic sections in interior western Alaska show near continuous sedimentological and environmental progressions extending from at least MIS 3, if not older, through MIS 1 (14,000 cal yr BP–present). The Kolmakof, Sue Creek, and VABM (vertical angle bench mark) Kuskokwim sections along the central Kuskokwim River, once a highland landscape at the fringe of central and eastern Beringia, contain aeolian deposition and soil sequences dating beyond 50,000 14C yr BP. Thick peaty soil, shallow lacustrine, and tephra deposits represent the MIS 3 interstade (or older). Sand sheet and loess deposits, wedge cast development, and very thin soil development mark the later MIS 3 period and the transition into the MIS 2 stade (29,000–14,000 cal yr BP). Loess accumulation with thicker soil development occurred between ~16,000–13,500 cal yr BP at the MIS 2 and MIS 1 transition. After ~13,500 cal yr BP, loess accumulation waned and peat development increased throughout MIS 1. These stratigraphic sequences represent transitions between a warm and moist period during MIS 3, to a cooler and more arid period during MIS 2, then a return to warmer and moister climates in MIS 1. [ABSTRACT FROM AUTHOR]

Clay minerals from the Indus Canyon and eastern clinoform since ~12 ka are uniformly rich in smectite and illite, similar to those from the Holocene Indus flood plains. A systematic enrichment of smectite in the proximal delta compared to the canyon and eastern clinoform argues for preferential capture of smectite close to the river mouth since ~12 ka. There is a rapid shift to a more smectite-rich assemblage in the canyon and eastern clinoform after ~5 ka. This change is probably caused by a change in sediment source, with less direct flux from the Himalaya and more erosion of older, weathered, smectite-rich sediment from the Indus River flood plains, driven by incision of the Indus and its tributaries into the floodplain as summer monsoon rains weakened. This influx of smectite is consistent with lower kaolinite/smectite values since ~5 ka. The onset of large-scale agricultural activities since ~5 ka, especially starting with the Harappan Civilization, may also have enhanced incision and erosion of floodplain sediments over the same time period. This study reports for the first time how monsoon strength variations since ~12 ka affected the clay mineral assemblages and sediment provenance in a major submarine canyon. [ABSTRACT FROM AUTHOR]

Despite many ideas about the age and processes of sand movements and paleosol formation, there are still some uncertainties in this relations in the Nyírség, eastern Hungary. The major aim of the present study was to clarify the chronology of fossil soils and blown-sand layers in the sand dunes of the Nyírség using radiocarbon (14C) dating on soil and charcoal samples. Charcoal and soil samples were collected from buried paleosols from different sand quarries for 14C dating. The bulk organic carbon content of the buried soil and charcoal pieces recovered from buried fossil soil layers allowed parallel 14C accelerator mass spectrometry dating in several cases. The new 14C results indicate paleosol development during Younger Dryas, while the preceding interstadial was assumed as a cold and dry period when only sand movement occurred in the area. Our results also confirm and support the previous assumptions, that in the Late Glacial, the first paleosol development period was during the Bølling-Allerød Interstadial. Four soil-forming periods could be determined during the Holocene (Preboreal, Boreal, Atlantic, Subatlantic). We have also indirectly identified sand movements during the Oldest Dryas, Younger Dryas, Preboreal, Boreal, and Subatlantic phase in the study area. [ABSTRACT FROM AUTHOR]

To identify chronological changes in the marine reservoir effect in southwest Japan, the radiocarbon ages of eight pairs of marine shells and terrestrial plants were measured from the same horizons of one core of Holocene sediments. This core was obtained from the northern part of the Sukumo Plain in southwestern Shikoku Island, which faces the warm Kuroshio Current. The drilling site is located in an area of subsidence associated with the convergence of the Philippine Sea Plate and the Eurasian Plate. On analyses of lithology, molluscan assemblages, and radiocarbon dating, we interpreted, from oldest to youngest, nine units: basement rock, a braided river channel, a meandering river channel, an estuary, a transgressive inner bay, Kikai-Akahoya volcanic ash, a deltaic inner bay, a tidal flat, and artificial soil. Changes in the depositional environment were mainly associated with sea-level rise after the end of the last glaciation. The reservoir ages of the eight pairs, 330 ± 70 yr, were obtained from a transgressive inner bay to deltaic inner bay sediments, formed during 4100–9200 cal BP. The chronological change in the reservoir effect allows us to correlate the Sukumo Core sediments with previous results from southwestern Japan, the Korean Peninsula, and Taiwan Island. [ABSTRACT FROM AUTHOR]

The introduction of agriculture is known to have profoundly affected the ecological complexion of landscapes. In this study, a rapid transition from C3 to C4 vegetation is inferred from a shift to higher stable carbon (13C/12C) isotope ratios of soils and sediments in the Benoué River Valley and upland Fali Mountains in northern Cameroon. Landscape change is viewed from the perspective of two settlement mounds and adjacent floodplains, as well as a rock terrace agricultural field dating from 1100 cal yr BP to the recent past (<400 cal yr BP). Nitrogen (15N/14N) isotope ratios and soil micromorphology demonstrate variable uses of land adjacent to the mound sites. These results indicate that Early Iron Age settlement practices involved exploitation of C3 plants on soils with low δ15N values, indicating wetter soils. Conversely, from the Late Iron Age (>700 cal yr BP) until recent times, high soil and sediment δ13C and δ15N values reflect more C4 biomass and anthropogenic organic matter in open, dry environments. The results suggest that Iron Age settlement practices profoundly changed landscapes in this part of West Africa through land clearance and/or utilization of C4 plants. [ABSTRACT FROM AUTHOR]

Pollen, spores, phytoliths, and microscopic charcoal from a sedimentary column in Hall's Cave, south-central Texas, provide information for local and regional vegetation change during the last deglaciation and the Holocene in the context of broader regional and global climatic changes. The combination of paleoenvironmental proxy data from the cave indicates that between about 18,000 and 16,500 cal yr BP the cave area was dominated by an open plant community consisting of herbaceous vegetation, dominated by C3 grasses, and scattered trees, primarily Quercus and Pinus species. After about 16,500 cal yr BP, the arboreal component fluctuated, attaining a peak between 14,000 and 13,000 cal yr BP with relatively equal proportions of C3 and C4 grasses, including a sizable proportion of Panicoideae grasses. The Younger Dryas is marked by a conspicuous decrease in arboreal pollen with an apparent increase of C4 grasses toward its termination. Early Holocene recovery of arboreal vegetation is followed by a drying trend marked by the increasing dominance of C4 drought-tolerant Chloridoideae grasses. Increasing human use of the cave in middle to late Holocene times creates noise in the climatic significance of pollen, phytolith, and other proxies, a factor to consider when interpreting paleoenvironmental proxies in other cave sedimentary records. [ABSTRACT FROM AUTHOR]

This contribution discusses possible relationships between human populations and Holocene environmental deterioration phenomena (cold/arid pulses and volcanic eruptions) in the Fuegian Archipelago (South America), based on summed probability distributions of archaeological dates, paleoenvironmental information, geospatial data, and archaeological evidence. During the first millennia after peopling, only the Hudson (ca. 7700 cal yr BP) and the first Monte Burney (ca. 8600 cal yr BP) eruptions might have played a role in human dispersion. Particularly, a more intense human occupation around the Beagle Channel and long-distance interactions are proposed as risk-buffer strategies related to the Hudson eruption. A cooling phase and a demographic growth at ca. 5500 cal yr BP might have favored more dispersed spatial occupations and a subsistence diversification in the Beagle Channel. In the northern steppes, the second Monte Burney eruption (ca. 4300 cal yr BP) and an arid episode (ca. 2600 cal yr BP) are proposed as the main triggers for changes in land-use patterns, long-network interactions, and subsistence strategies. Even though occupation changes in the Fuegian Archipelago coexist with environmental deterioration episodes after 1500 cal yr BP, demographic processes and the European colonization most likely explain this trend. Similarities between the steppe/ecotone and forest occupation curves suggest common behavioral patterns across the Holocene. [ABSTRACT FROM AUTHOR]