Published by MDPI AG
Online ISSN: 2571-550X
Pollen and sediment data from a 10.5 m-deep alluvial exposure and a secondary tributary exposure at Upper Arroyo, a seasonal river, in Saltillo, Mexico, were examined with the aim of reconstructing the vegetation and environmental history during the Holocene as a whole. The role of climate change in Chihuahuan Desert flora development after 8800 BP was assessed, in addition to more local physiographic factors, such as erosion and accumulation, soil development and denudation, and hydrological entrenchment. Climate change appeared to have been a principal agent of vegetation change in the Early and Middle Holocene, with a periodic expansion of desert vegetation. A reduction in the environmental carrying capacities for mesophytic flora according to physiographic factors, such as soil erosion and channel entrenchment, was then identified after 2300 BP, also promoting azonal ecological niches for xerophytic vegetation in southern Coahuila, Mexico, that persist despite modern variations in precipitation.
Age-depth model for El Gancho.
Measured, calibrated and modelled 14 C ages from El Gancho.
The Central American Dry Corridor (CADC) is the most densely populated area of the Central American Isthmus and is subject to the greatest variability in precipitation between seasons. The vegetation of this region is composed of Dry Tropical Forests (DTF), which are suggested to be highly susceptible to variations in climate and anthropogenic development. This study examines the vulnerability of past DTF surrounding the Asese peninsula, Nicaragua to climatic and anthropogenic disturbances over the past c. 1200 years. Past vegetation, climate, burning, and animal abundance were reconstructed using proxy analysis of fossil pollen, diatoms, macroscopic charcoal, and Sporormiella. Results from this research suggest that DTF have been highly resilient to past climatic and anthropogenic perturbations. Changes in DTF structure and composition appear to be linked to the abundance and intensity of fire. Pre-Columbian anthropogenic impacts on DTF are not detected in the record; however, DTF taxa decline slightly after European contact (1522 C.E.). Overall the DTF for the Nicaraguan region of the CADC were found to be highly resilient to both climatic and anthropogenic disturbances, suggesting that this region will continue to be resilient in the face of future population expansion and climatic variation.
Numerous loess/paleosol sequences (LPS) in the Carpathian Basin span the period of Marine Isotope Stage (MIS) 2 and the last glacial maximum (LGM). Nevertheless, only two known records—Madaras and Dunaszekcső—preserve highly resolved records with absolute chronologies with minimal uncertainties, which enable the meaningful assessment of feedbacks and short-term climatic fluctuations over this period. The Madaras profile is located at the northern margin fringe of the Bácska loess plateau; Dunaszekcső, located on the Danube to its west, yields a chronology built on over 100 14C dates yet spans only part of MIS 2, missing half of the LGM including its peak. Here, we add to the previously published 14C chronology for Madaras (15 dates) with an additional 17 14C and luminescence ages. Resulting age models built solely on quartz OSL and feldspar pIRIRSL data underestimate the 14C based chronology, which is likely based on inaccuracies related to luminescence signal behavior; we observe age underestimations associated with unusual quartz behavior and significant signal loss, a phenomenon also observed in Serbian and Romanian loess, which may relate to non-sensitized grains from proximal sources. Our new chronology provides higher resolution than hitherto possible, yielding consistent 2 sigma uncertainties of ~150–200 years throughout the entire sequence. Our study indicates that the addition of further dates may not increase the chronological precision significantly. Additionally, the new age model is suitable for tackling centennial-scale changes. The mean sedimentation rate based on our new age-depth model (10.78 ± 2.34 years/cm) is the highest yet recorded in the Carpathian Basin for MIS 2. The resolution of our age model is higher than that for the Greenland NGRIP ice core record. The referred horizons in our profile are all characterized by a drop in accumulation and a higher sand input, the latter most likely deriving from nearby re-exposed sand dunes.
The tomographic images of cave lion cubs' skulls and mandibles with marked deciduous teeth: (a) Sparta's skull; (b) Boris's skull; (c) Sparta's mandible.
Appearance of the frozen mummies of fossil cave lion cubs: (a) female Sparta; (b) male Boris. Photos of lion cubs' heads from the side: (c) Sparta; (d) Boris; (e) Sparta mummy as seen from above; (f) dark brown 'brush' of Sparta's tail.
Frozen mummy of the cave lion cub named Uyan, Uyandina River, Yakutia.
The tomographic images of Sparta's body from the left side: (a) skin; (b) skull and spine. The spinal bones: C-cervical vertebrae, T-thoracic vertebrae, L-lumbar vertebrae, S-sacral vertebrae, Ca-caudal vertebrae.
Selected paintings of adult cave lions from Chauvet cave, showing interesting colouration on their head fur. Pictures: P. Fosse, numbers labelled as in Clottes and Azéma [40].
A preliminary description is presented of the well-preserved frozen mummies of two cubs of the extinct cave lion Panthera spelaea (finds of 2017–2018, Semyuelyakh River, Yakutia, eastern Siberia, Russia). The fossil lion cubs were found in close proximity, but they do not belong to the same litter, since their radiocarbon ages differ: the female (named ‘Sparta’) was dated to 27,962 ± 109 uncal years BP, and the male (named ‘Boris’) was dated to 43,448 ± 389 uncal years BP. The lion cubs have similar individual ages, 1–2 months. The general tone of the colour of the fur coat of Sparta is greyish to light brown, whereas, in Boris, the fur is generally lighter, greyish yellowish. It is, therefore, possible that light colouration prevailed with age in cave lions and was adaptive for northern snow-covered landscapes. The article discusses the results of computed tomography of cubs of the cave lion, the possible reasons for their death, and the peculiarities of their existence in the Siberian Arctic.
The examined material (207 bones and bone fragments) of 53 avian taxa from two human cave dwellings is dated between 24,000 ± 1000 BP and 9400 ± 100 BP. It reveals that 49.0% of the bird species/taxa disappeared from the recent bird fauna of the Thanh Hoa Province; 39.6% disappeared from the recent bird fauna of North Vietnam (except Thanh Hoa Province); 33.9% disappeared from the recent bird fauna of Vietnam (except North Vietnam); 28.3% are not extant in the recent bird fauna of Indochina (except Vietnam); and 52.8% disappeared from the recent bird fauna of Southeast Asia (except Indochina). This suggests more considerable influence of the Late Pleistocene climatic events on the environment and bird fauna than previously accepted in the Eastern part of the Indochinese peninsula in the last 24–millenia. The gallinaceous birds are best represented. Of the 39 Southeast-Asian species, 18 species/taxa (46.2 percent) are Galliforms. They consist of 34 percent of all bird taxa recorded in both caves. Four categories of the IUCN Red List have been represented among the established birds in the sites: LC—28, NT—7, VU—2 (Buceros bicornis and Rhyticeors undulates), and CR—2 (Lophura edwardsi and Rhinoplax vigil).
We investigated 34 sediment cores to reconstruct spatiotemporal variations in hypolimnetic hypoxia for the past 200 years in Lehmilampi, a small lake in Eastern Finland. As hypoxia is essential for varve preservation, spatiotemporal changes in varve distribution were used as an indicator for hypolimnetic hypoxia oscillations. The hypoxic water volume was used as a variable reflecting hypolimnetic hypoxia and determined for each year by estimating the water volume beneath the water depth where shallowest varves were preserved. As a result, seven hypoxia periods, highlighting the variations in hypolimnetic hypoxia, are established. These periods may be influenced by bioturbation, lake infill, and lake level changes. Furthermore, we evaluated the relationship between hypolimnetic hypoxia oscillations and climatic factors. Diatom assemblage changes were also analyzed to estimate whether the hypoxia periods could be related to anthropogenic eutrophication. The diatom analyses suggest relatively stable nutrient conditions for the past 200 years in Lake Lehmilampi. Climate, on the other hand, seems to be an important driver of hypoxia oscillations based on correlation analysis. The role of individual forcing factors and their interaction with hypolimnetic hypoxia would benefit from further investigations. Understanding climatic and anthropogenic forcing behind hypolimnetic hypoxia oscillations is essential when assessing the fate of boreal lakes in a multi-stressor world.
Average monthly precipitation and temperature for Thailand for 30 years from 1985 to 2014. Data sourced from the Climatic Research Unit (CRU) multivariate climate dataset [23].
Location of proxy records in Thailand.
A plot comparing historic ENSO events to climatic proxies. (a) Standardised Tree Ring Width [29] (R 2 =0.02). (b) Stalagmite δ 18 O values [31] (R 2 = 0.27). (c) The MEI.v2 ENSO index (sourced from: https://www.esrl.noaa.gov/psd/enso/mei/) spanning 1871 to 2009. Red shading highlights El Niño events (>0.5), and blue shading depicts La Niña events (<−0.5).Trendlines are present to show the overall gradual change to a drier climate.
A plot comparing climate proxies and modelled sea surface temperature (SST) anomalies from 425 BC to 1964 AD. (a) Stalagmite δ 18 O values [31], the grey lines represents the raw data which is overlaid by black smoothed data using the Savitzky-Golay filter (R 2 = 0.25). (b) Sediment core δ 13 C values [30]. (c) Modelled SST for Niño region 3.4 spanning from the TraCE-21ka simulation (sourced from Earth System Grid: https://www.earthsystemgrid.org/project/trace.html). Blue shaded areas represent drought periods discussed by the papers associated with each proxy. The grey shaded area shows the hiatus in the sediment core. Trendlines are present to show the overall gradual change to a drier climate.
Irregular climate events frequently occur in Southeast Asia due to the numerous climate patterns combining. Thailand sits at the confluence of these interactions, and consequently experiences major hydrological events, such as droughts. Proxy data, speleothem records, lake sediment sequences and tree ring chronologies were used to reconstruct paleo drought conditions. These trends were compared with modelled and historic El Niño Southern Oscillation (ENSO) data to assess if the ENSO climate phenomena is causing droughts in Thailand. Drought periods were found to occur both during El Niño events and ENSO neutral conditions. This indicates droughts are not a product of one climate pattern, but likely the result of numerous patterns interacting. There is uncertainty regarding how climate patterns will evolve under climate change, but changes in amplitude and variability could potentially lead to more frequent and wider reaching hydrological disasters. It is vital that policies are implemented to cope with the resulting social and economic repercussions, including diversification of crops and reorganisation of water consumption behaviour in Thailand.
Editorial summaries of selected papers relevant to Quaternary science published in high-impact multidisciplinary journals between December 2018 and February 2019 [...]
Editorial summaries of selected papers relevant to Quaternary science published in high-impact multidisciplinary journals between 12 September and 10 December 2018. [...]
After an extensive voting period, we are proud to present the winner of the Quaternary Young Investigator Award: Dr. Oana Alexandra Dumitru [...]
Cosmogenic radionuclide information for samples from the stratigraphic layer Geo 2b of Tsiotra Vryssi.
In the published manuscript, the study presents diverse geochronological and biochronological data providing age constraints on the site of Tsiotra Vryssi (Mygdonia basin, Greece). One of the methods presented is based on burial ages from cosmogenic radionuclides. Table 2 of this study reports cosmogenic simple burial ages of 1.88 ± 0.16 Myr, 2.10 ± 0.18 Myr, and 1.98 ± 0.18 Myr (for samples COSMO 1, 2, and 3, respectively). However, after publication of the manuscript, a small error was found in the calculation of these ages. In particular, it concerns a typo in the MatLab code resulting in a too-low value for the fast muonic 10Be production rate, which affected the last column of Table 2 with the simple burial ages. After correcting this mistake, the ‘corrected’ simple burial ages in Table 2 (as well as in Figure 9) should be 1.54 ± 0.10 Myr, 1.75 ± 0.10 Myr, and 1.62 ± 0.10 Myr. These ages, as were the original published ages, are the minimum possible burial ages from this technique. Therefore, the deposit with normal polarity containing the cosmogenic samples is attributed to the Olduvai subchron (1.95–1.78 Myr). The age of the overlying layer showing a reverse polarity and containing the vertebrate fossils is therefore the same as was originally published (<1.78 Myr), and overall, an age between 1.78 and ~1.5 Myr is proposed for the Tsiotra Vryssi fauna. We emphasize that the corrected ages mentioned here do not change the interpretations of the Konidaris et al. 2021 study, and we present this Erratum so that future studies using these data have access to the corrected values.
Geological map of Pasaman (Indonesia Geological Agency).
Moment rate function, focal mechanism, and comparison of observation data (black line) and synthesis data (red line) at seismic stations used in the Pasaman earthquake inversion analysis. The small ball on focal mechanism shows the number of recorded seismic stations, red for the compression zone and white for the dilation zone.
A Mw 6.1 earthquake on 25 February 2022, at around 8:39 a.m. local time, struck Pasaman Barat Regency, West Sumatra, Indonesia, and was felt in Singapore and Malaysia. The hypocenter of this earthquake was 12 km deep and preceded by an Mw 4.9 foreshock a few minutes earlier. The earthquakes originated on a blind fault and triggered a landslide at Mount Talamau. Herein, the slip distribution and asperities along the plane fault during the earthquake were examined by teleseismic inversion and the fault location was identified by Global Gravity Model plus (GGMPlus) satellite gravity data. The slip distribution was calculated from the source parameters (strike: 136°; dip: 70°; rake: 174°) by inversion techniques based on teleseismic data. Based on the slip distribution, the earthquake was generated by stress from the Sianok fault that spread to the north and reached the uncertain fault segment in the Talamau area. In addition, the results of the First Horizontal Derivative and Second Vertical Derivative from the GGMplus data revealed a straight Simple Bouguer Anomaly pattern, confirming the existence of the uncertain Talamau fault as part of the Great Sumatra Fault. This work shows the potential application of the combination of teleseismic and gravity observation for delineating the fault structure that caused the 2022 Mw 6.1 Pasaman earthquake, which can also be applied to other locations of similar geological backgrounds.
(A) Map of South America and Santa Cruz, Argentinian Patagonia, that shows the geographical location of the study site and other paleoenvironmental records used in regional paleoenvironmental reconstruction. 1-Buenos Aires Lake [21]; 2-Pueyrredón Lake [22-24,26,27]; 3-Belgrano Lake (PNPM) [37]; 4-The Deseado Massif [20,32]; 5-San Martín Lake [18,19]; 6-Argentino
Pollen diagram in percentages (%) of the COCU archaeological sequence.
Reconstruction of the dynamics of the plant communities of the Pueyrredón Lake area (47 • S) using the pollen information of the ZB wet meadow sequence and the COCU archaeological sequence for the last 2900 cal yr BP.
Radiocarbon ages of ZB, COCU and calibrations in accordance with [63].
Patagonian shrub and ecotonal communities were sensitive to past environmental changes and thus may also be affected by future ones. Therefore, their paleoecological study constitutes a valuable tool to understand the way in which these plant communities respond to the forcings responsible for environmental variability. The aim of this paper is to reconstruct the vegetation dynamics of the Pueyrredón Lake area (47°25′55′′ S; 72°0.7′7′′ W) for the last 3000 cal yr BP and to contextualize these changes in a regional paleoclimatic framework. The results indicate that at the beginning of the 2900 cal yr BP, the vegetation in the northwest of Santa Cruz, Argentinian Patagonia, was represented by a grass-shrub steppe associated with forest–shrub steppe ecotonal elements. This information correlates with the larger-scale environmental inferences described for the period, which indicate an increase in moisture availability due to the weakening of the westerly winds. A marked change to arid conditions is indicated in the last 1050 cal yr BP, with the establishment and development of different shrub steppe communities and the lack of ecotonal elements. Although vegetation was sensitive to changes in moisture conditions related to the variability of the westerly winds, there is evidence of differences in the composition of shrub vegetation regarding the sequences analyzed. Variations in pollen proportions of the shrub steppes in the Pueyrredón Lake area suggest that changes in vegetation are not only due to climate variability but also local factors in the areas where shrub communities grow. The integration of the information with other Patagonian sequences allowed to frame these changes in a regional context. The results obtained provide useful information to understand the way vegetation changed in the past and the manner in which it may respond to future changes.
Recent findings of archaeological research in the Vathy gulf area, Astypalaia island, indicate its continuous habitation since prehistoric times, most importantly in the transitional period from the Final Neolithic to the Early Bronze Age (late 4th/early 3rd millennium BC). The evaluation of the prehistoric stone artefacts from Vathy using non-invasive analytical methods (Near Infrared Spectroscopy—NIR), in combination with the mineral-petrographic characterization of the main lithological formations of the island, is expected to provide important information about raw material procurement and possible exchange networks. The geological study of the island combined with the analytical methods applied to the archaeological artefacts and the geological samples led to the identification of both local and allogenic materials. The possible locations of raw material sources were established and the origin of allogenic materials was estimated. The stone artefacts made of local geo-materials consist mainly of calcitic sandstone, shale, marl, and limestone/marble, comprising the largest part of the lithological formations of the island, as well as pumice and volcanic rocks of varying chemical composition. By means of a portable microscope and NIR spectroscopy, we were further able to identify allogenic geo-materials including chalcedony, mica schist, bauxite and meta-bauxite, steatite, and paragonite. Based on the mineralogical and petrographic characterization of the stone artefacts, a first attempt is made to evaluate the possible raw material sources and to identify potential intra-island modes of stone exploitation.
A high-resolution multiproxy sedimentary record comprising pollen, charcoal, trace element, stratigraphy and particle size data is used to reveal environmental changes from the mangrove ecosystem at Unguja Ukuu, Zanzibar, Tanzania, over the last 5000 years. Historical human–environment interactions over the last millennia are explored by a comparison of the stratigraphic and archaeological data. The area was characterised by a mixture of mangrove forest and beaches, indicating a low level of tidal inundation to at least 3300 BCE. From 2750 BCE, mangrove forest expanded as the area experienced sea-level rise. Further sea-level rise is recorded between 600 and 1100 CE, indicated by the pollen record, particle size analysis and the presence of shell fragments. After 1100 CE, mangrove forest decreased with back mangrove species increasing, indicating a falling sea level. Cocos nucifera decreased after 1900 CE, which reflects a recent sea-level rise and possibly a phase of exploitation. Cereal pollen shows a high presence at around 1500 CE, which coincided with the arrival of the Portuguese on Zanzibar and the transition to Omani colonisation. The sedimentation rate in the core top indicates that mangroves in Unguja Ukuu cannot keep pace with the current rate of sea-level rise.
The distributions of the archaeological sites from 11,500 to 7000 cal BP (The name of the sites: 1: Zhuannian [37]; 2: Donghulin [38]; 3: Nanzhuangtou [39]; 4: Ximiao [40]; 5: Yujiagou [41]; 6:
Graphic comparison of human occupation intensity and climate fluctuation. The shaded gray bar shows the time span of the 8.2 ka BP cooling event. The curve (A) represents hemispheric changes in precipitation and temperature recorded in the North Greenland ice core [81]. Higher δ 18 O values indicate warmer temperatures and higher humidity. The curve (B) represents a proxy for monsoon intensity in South China from the Dongge Cave stalagmite records [31]. Higher δ 18 O values indicate strong winter monsoons (cold/dry) and lower δ 18 O values indicate stronger summer monsoons (warm/wet). The curve (C) represents a proxy for monsoon intensity in North China from the Lianhua Cave stalagmite records [33,82]. Higher δ 18 O values indicate strong winter monsoons (cold/dry) and lower δ 18 O values indicate stronger summer monsoons (warm/wet). The curves in (D) and (E) respectively indicate the relative occupation intensity of the Early Neolithic and the transitional sites across North China based on the sum probability of radiocarbon age estimates. The basic information of the radiocarbon dates (including the dataset of the radiocarbon dating and the explanation of how the sum probability distribution model was built) is presented in the supplementary data.
Features and artifacts found from transitional sites (11.5-8.5 ka BP) which show the innovative cultural traits that herald the "Neolithic package" and differ from typical Paleolithic remains (1: sedentary burial, Donghulin site (2 in Figure 1); 2: stone-lined hearth, Donghulin site (2 in Figure 1); 3: Pottery bowl, Zhuannian site (1 in Figure 1); 4: pottery sherd with decorations on the rim, Donghulin site (2 in Figure 1); 5: stone slab and rollers Bianbiandong site (7 in Figure 1); 6: stone slab and roller, Donghulin site (2 in Figure 1), the maximum length and width are marked in the graph, after [37,38,43]).
The items possibly used as ritual paraphernalia in the Jiahu site ((A) turtle shell with gravel, found in burial M363; (B) bone folk-shaped item; 1: found in burial M395, 2: found in burial M363. (C) bone flute; 1: found in burial M57, 2: found in burial M68; after [47])).
Toolkits of the Jiahu site which show the intensity of the techniques of food acquisition (1: stone slab and roller, the size of the stone slab is marked in the figure; 2: stone hoe; 3~4: stone sickle; 5~8: bone harpoon; 9~10: arrowhead, after [47]).
Early Neolithic lifeways in North China, which are marked by a low-level food production economy, population aggregation, and sedentism, thrived just after the period of a climatic cooling event at 8.2 ka. Instead of simply regarding this climate fluctuation as a cause for the significant socio-economic transition, this paper attempts to explore the interplay between people’s choices of coping strategies with climate change as a perspective to learn how people respond to this climate fluctuation and how such responses generated the interlocked socio-economic transitions. This analysis indicates that pre-existing changes in human adaptive behaviors prior to the cooling events were sufficient to enable people in certain areas to apply the intensification of food procurement in circumscribed territories as a strategy to cope with the climate fluctuations of the 8.2 ka BP cooling event. The application of such a coping strategy facilitated the economic and sociopolitical transition into Neolithic lifeways and led to the flourishing development of Neolithic cultures after 8 ka BP in North China.
Lithology of composite profile SPUR-A, composed of five overlapping sediment cores SPUR-A-1 to SPUR-A-5 from Spur Bog, and positions of plant macrofossils sampled for radiocarbon dating.
Lithology, loss of ignition (LOI), selected pollen species/groups data, charcoal, the humification index, and grain size data of Spur Bog core SPUR-A on a time scale and interpretation of multi-proxy data with regard to climatic and environmental changes (for detailed references, see Section 4.2). Dotted lines indicate major lithological changes. Abbreviations: LIA = Little Ice Age; MWP = Medieval Warm Period.
Pollen percentages of selected arboreal, shrub, herbaceous and aquatic pollen types in Spur Bog compared to lithology, total AP and macro-and microcharcoal fragment counts. See Figure 7 for the key of the lithological log.
Schematic maps and cross-section models (not to scale) depicting geomorphological changes at the South Haven Peninsula and landscape/ecological changes at the site of Spur Bog (red star) during the last ~900 years. (a) The period ~1150-1210 AD: intertidal zone; (b) ~1210-1390 AD: coastal floodplain with saline tolerant grassland; (c) ~1390-1470 AD: sporadically flooded coastal wetland; (d) ~1470-1610 AD: dune-protected coastal wetland and heathland; coastline defined by using the map from [17]; (e) ~1610-1720 AD: spur peat bog development in an expanding grassland environment; increase in wildfire activity; coastline defined by using the map from [6,23]; (f) ~1720-1780 AD: spur peat bog development; transition from grassland to mixed woodland; development of Little Sea; decrease in wildfire activity; coastline defined by using the map from [6,25]; (g) ~1780-1880 AD: spur peat bog fully established; further development of Little Sea; further expansion of woodlands; coastline defined by using the map from [6,26].
AMS radiocarbon dates for samples extracted from the Spur Bog composite profile SPUR-A.
A multi-proxy palaeoenvironmental dataset (LOI, pollen, charcoal, grain sizes and the humification index) was extracted and radiocarbon dated from a sedimentary sequence from Spur Bog, central South Haven Peninsula (Dorset, southern England) to reconstruct ecological and environmental changes within the last ~900 years. These analyses reveal highly unstable environmental conditions at the site, evidencing the occurrence of multiple, often rapid changes during this period. The results significantly expand upon the existing palaeoenvironmental and geomorphological frameworks of the South Haven Peninsula which previously relied upon sparse, vague historical records prior to ~1750 AD. The multi-proxy dataset of Spur Bog sediments recorded a primary “development” phase (~1150–1470 AD) during which marine processes were the dominant control upon environmental conditions at the site, resulting in marked geomorphological changes that lead to the progressive eastward expansion of the South Haven Peninsula. This is followed by a secondary “maturation” phase (~1470–1880 AD) during which the Spur Bog sequence exhibits significant ecological changes in response to fluctuations in sea level, coastal erosion and human activity, demonstrating the vulnerability of the site to future climatic and anthropogenic pressures.
Global warming is expected to increase the rate of CH4 emission from acidic peatlands leading to an increased interest on its mechanisms of formation. The main routes are through the reduction of CO2 by molecular hydrogen and through the cleavage of acetate. A predominance of the former, a reaction which also competes with homoacetogenesis to form acetate, may enrich the media in acetate, which could potentially be incorporated in the peat molecular markers. Acetates of triterpenoid biomarkers have been identified in peats and lake sediments and related to the input of higher plants. Nevertheless, the acetyl derivatives are found in very low amounts in fresh plants and in much lower amount than other derivatives with alcohol or ketone functional groups. The dichloromethane/methanol extracts of Asturian peat bog profiles (North Spain) were analyzed using gas chromatography/mass spectrometry (GC/MS) and compound-specific-isotope-analysis (CSIA). They show abundance of acetates of compounds with oleanane, ursane, and lupane skeletons derived from higher plants and with hopane skeleton, which can be considered a characteristic of these peats. Two families of 3-oxyhopenyl acetates with -17(21)- and -22(29)- configurations were detected in the upper part of the peat profiles, having a δ13C isotopic composition enriched by 4‰ compared with that of higher plant triterpenoids, and similar to that of microorganism-derived regular hopanoids. Both the acetate and ketone derivatives with the oxygenated functionality at C-3 were generally present in a given extract and tended to accumulate at certain depth in the profiles and in specific levels. The widespread occurrence of acetyl-derivatives, their higher concentration in the deeper layers of the peat, the fact that the acetates correspond to different compound families of diverse source and the very low amount of acetates identified in Ericaceae-contributing to the peat compared to the alcohols suggest that they were formed in the peat under particularly favorable environmental conditions. We postulate that these conditions could have been the existence of a medium enriched in acetic acid produced by the dominance of hydrogenotrophic methanogenesis and/or homoacetogenesis over acetoclastic methanogenesis. This phenomenon that has been preferentially described in Sphagnum bogs at high latitudes, and in the deeper layers of peat, appears to be also present in the temperate peats of the Asturian coast.
Grain size compositions plotted on separated line diagrams, GSI and U-ratio line diagrams [12,14,15,19,22,26-29].
Highlighted geochemical results from XRF (major elements above, trace elements below).
Geochemical indices used to explore weathering in the loess-paleosol sequence.
The loess-paleosol profile near the settlement of Pécel has a notable size among the loess-paleosol sequences of the Northern Carpathian territories. Therefore, comprehensive sedimentological examinations were performed to understand the profile and the information preserved in it. The past periodicity and intensity of winds were showed by particle composition studies (GSI, U-ratio). At least two source areas can be presumed based on geochemical indices (CIA, CIW, Rb/Sr, Zr/Rb). Based on the characteristics of the chemical composition of sulphide minerals (P, S, Pb, Ni, As sulphides), the lower 10 m of the profile was supposed to be transported from the NW direction (Buda Thermal Karst, Börzsöny, Cserhát). Sufficient information is not yet available in order to determine the source area of the upper 10 m. By using the mentioned indexes, major developing and weathering horizons also could be identified.
The Chalcolithic levels of El Portalón de Cueva Mayor (Atapuerca, Burgos, Spain) offer a good opportunity to test whether the small-mammal contents of different archaeo-stratigraphical units may be useful to characterize them as independent entities. With that purpose, we studied representative samples of small-mammal remains from the two main contexts identified: the Early Chalcolithic (EC) funerary context and the Late Chalcolithic (LC) habitat/stabling context, with the latter comprising three different archaeological units according to their origin, namely prepared floors, activity floors and stabling surfaces or fumiers. Following the distribution of taxa in their respective contexts, we performed several statistical tests to check for significant discrepancies between archaeological units. The exclusive presence of certain taxa, together with the statistical difference in relative taxonomic ratios, points to the integrity and unpolluted condition of the EC context. The interspersed arrangement of the different LC context’s units made them prone to inter-pollution as they are not statistically different. The unexpected presence of Pliomys lenki and Chionomys nivalis in the prepared floors evidences their Upper Pleistocene allochthonous origin. The EC levels of El Portalón contribute the first Holocene records of nine taxa in the Sierra de Atapuerca. An environment dominated by woodland, shrubland and wet meadows, with moderate presence of grassland, inland wetlands and rocky areas, is inferred from the small-mammal association of the EC levels.
Evolution of speleothem palaeoclimate research. Data from top to bottom: "Web of Knowledge" are the publications that resulted from querying the keywords "speleothem" and "isotope" in http://www.webofknowledge.com on 10 June, 2018 (may include publications only using the records). Speleothem records identified by SISAL working group members. Records in the SISAL database [16,17]. Speleothem records lodged in the NOAA repository as of 5 October, 2108
Isotopic records from speleothems are an important source of information about past climates and, given the increase in the number of isotope-enabled climate models, are likely to become an important tool for climate model evaluation. SISAL (Speleothem Isotopes Synthesis and Analysis) have created a global database of isotopic records from speleothems in order to facilitate regional analyses and data-model comparison. The papers in this Special Issue showcase the use of the database for regional analyses. In this paper, we discuss some of the important issues underpinning the use of speleothems and how the existence of this database assists palaeoclimate research. We also highlight some of the lessons learned in the creation of the SISAL database and outline potential research going forward.
The three researchers who developed the ideas that constitute the theoretical foundations of the strong fuzzy EHLFS (Environmental-Human-Landscape Feedbacks and Synergies) approach. (A) Thomas Chrowder Chamberlin (1843-1928) in the 1870s. Source: University of Wisconsin-Madison Archives. (B) Karl Raimund Popper (1902-1994) in the 1980s. Source: Library of the London School of Economics and Political Science. (C) John Rader Platt (1918-1992). Source: Google Arts & Culture. Photographs with license Wikimedia Commons.
Schematic view of the EHLFS holistic approach. E: Environment, L: Landscape, H: Humans. Feedbacks are represented by blue arrows and synergies in red arrows. Grey arrows represent internal feedbacks.
The pristine condition and the types of determinism discussed in this paper, under the general EHLFS framework. See Figure 2 for details.
Location sketch-maps and moais. (A) Map of the Pacific Ocean and its main islands and archipelagos. Easter Island is highlighted by a red dot. (B) Map of Easter Island, showing the location of the freshwater bodies discussed in the text. Ahu Tongariki (see (C)) is represented by a red dot. (C) Moais of Ahu Tongariki, close to Lake Raraku, see B for location (Photo: N. Cañellas).
EHLFS holistic approach for Easter Island's ecological and cultural changes, as is suggested in this paper. See Figure 2 for details.
Although the interpretation of Quaternary records of interrelated environmental–ecological–human processes is necessarily complex, it is often addressed using too-simple deterministic approaches. This paper suggests a holistic framework called EHLFS (Environmental–Human–Landscape Feedbacks and Synergies) to tackle Quaternary complexity. The EHLFS scheme is a multiple-working-hypotheses framework, able to account for the particular nature of Quaternary research, and is used in combination with the strong inference method of hypothesis testing. The resulting system is called the strong fuzzy EHLFS approach. This approach is explained in some detail and compared with the more extended simplistic determinisms—namely the environmental determinism and the human determinism—as well as with dual determinisms or deterministic approaches based on two contrasting and apparently contradictory and excluding hypotheses or theories. The application of the strong EHLFS methodology is illustrated using the Late Holocene ecological and cultural history of Easter Island since its initial human settlement, a topic that has traditionally been addressed using simplistic and dual deterministic approaches. The strong fuzzy EHLFS approach seems to be a robust framework to address past complex issues where environment, humans and landscape interact, as well as an open system able to encompass new challenging evidence and thorough changes in fundamental research questions.
Explaining the multifaceted, dynamic interactions of the manifold factors that have modelled throughout the ages the evolutionary history of the biosphere is undoubtedly a fascinating and challenging task that has been intriguing palaeontologists, biologists and ecologists for decades, in a never-ending pursuit of the causal factors that controlled the evolutionary dynamics of the Earth’s ecosystems throughout deep and Quaternary time. [...]
Map of the Eastern Mediterranean showing the locations of marine cores sampled in this study (purple stars: LC21, KL51 and ODP967), the potential tephra source regions (red triangles: numbered 1-10), and other locations mentioned in the text (purple circles are marine sediment cores, green circles are terrestrial environmental records).
Detailed core photograph and sedimentological features of core KL51 showing the position and preservation of the KL51 S5 tephra layer and the correction for shrinkage in the core between Sections 3 and 4. The KL51 S5 tephra layer is located at an original depth in the core of 346.3-346.8 cm (see [60]) which after correction for core shrinkage, becomes 348.3-348.8 cm. This study uses the original depth of 346.3-346.8 cm to retain consistency with previous studies [60].
Photomicrographs (transmitted light) of the eight samples of tephra from cores LC21, KL51 and ODP967B. The labels "T" shows good examples of the tephra shards for each sample. See Figure 2 for the stratigraphic position of each sample. The slight blurring around the shards in LC21 975.5 and 993.5 is likely due to the age of the mounting medium in these samples.
Top left: Total Alkali vs. Silica (TAS) diagram (after [77]) showing samples analysed in this study. Other panels show selected major element biplots of glass geochemistry from electron probe microanalysis (EPMA) of the tephra samples in this study. Reproducibility is <10% relative standard deviation for analyses with concentrations >0.8 wt% with the exception of Na2O (14%-15%). Full analytical results and standard analyses are provided in the supplementary data. Data for the LC21 970.9 (visible) tephra and LC21 957.5 are from [17]. Also shown are analyses of proximal tephras for comparison from: Santorini [48], Eastern Anatolia [78]; Central Anatolia including Acigöl [48,79]; Kos [17]; Nisyros [58]; Yali [13,14]. The geochemical field defined by proximal analyses of the Vourvoulos eruption of Santorini is shown separately from the rest of the Santorini field; see discussion in text.
Chronology of sapropel S5 and tephra layers (red lines) in Eastern Mediterranean marine cores ODP967B-2H1, LC21, and KL51. All records as in Figure 2, but plotted against age instead of depth following the sapropel chronology of [22,54]. LC21 age scale within the sapropel is not shown, due to possible changes in the sedimentation rate in this core; see text for discussion. Numbered red lines (1, 2, 3? and 4) indicate proposed tephra layer based on the major element glass chemistry and relate to the numbers of the data clusters defined by the DFA (Figure 6). Tephra 1 in LC21 is shown over a range of depths (red box) reflecting the depth uncertainty of the correlation with KL51 346.8; the analyses of all tephra samples within this red box in LC21 (899.5, 941.5 and 959.5 cm) are indistinguishable from one another. Tephra layer 2 is represented by sample LC21 970.9 (visible), tephra layer 3? is a possible eruption event represented by sample LC21 975.5 and tephra layer 4 is represented by samples ODP967B-2H1 129.5 and LC21 993.5. Shard, Ba and V counts in LC21 have been aligned to the KL51 core on the cautious interpretation that sample LC21 941.5 is synchronous with the KL51 346.8 (visible) tephra; see supplementary information for discussion.
The Eemian was the last interglacial period (~130 to 115 ka BP) to precede the current interglacial. In Eastern Mediterranean marine sediments, it is marked by a well-developed and organic-rich “sapropel” layer (S5), which is thought to reflect an intensification and northward migration of the African monsoon rain belt over orbital timescales. However, despite the importance of these sediments, very little proxy-independent stratigraphic information is available to enable rigorous correlation of these sediments across the region. This paper presents the first detailed study of visible and non-visible (cryptotephra) layers found within these sediments at three marine coring sites: ODP Site 967B (Levantine Basin), KL51 (South East of Crete) and LC21 (Southern Aegean Sea). Major element analyses of the glass component were used to distinguish four distinct tephra events of Santorini (e.g., Vourvoulos eruption) and possible Anatolian provenance occurring during the formation of S5. Interpolation of core chronologies provides provisional eruption ages for the uppermost tephra (unknown Santorini, 121.8 ± 2.9 ka) and lowermost tephra (Anatolia or Kos/Yali/Nisyros, 126.4 ± 2.9 ka). These newly characterised tephra deposits have also been set into the regional tephrostratigraphy to illustrate the potential to precisely synchronise marine proxy records with their terrestrial counterparts, and also contribute to the establishment of a more detailed volcanic history of the Eastern Mediterranean.
Coring lakes and water bodies for paleoecological studies often involves using a coring platform to properly operate a sediment sampling device. In the past, coring platforms have been developed by specific paleoecology laboratories or by private companies. Those coring platforms are generally composed of two boats (inflatable boats, kayaks, etc.) connected together by a metallic and wood structure. While these coring platforms have proven their efficacy, they are not ideal in several coring settings requiring remote transportation, and their cost may be prohibitive for less funded paleoecological laboratories. On this technical note, we describe the Light, Affordable, Stable, and Transportable (LAST) coring platform. Coring platforms based on these principles and on the design presented herein have been extensively tested in various conditions and countries by our research group and collaborators. In the first part of this manuscript, we present the principles and the design of the LAST coring platform; then, we discuss the coring setting for which the LAST coring platform is suitable, and its possible limitations. Associated with this manuscript, we provide a construction and assemblage manual developed without words and with simple illustrations in order to make it easily accessible to speakers of any language.
Elaboration from data published by Klein Goldewijk, Dr. ir. C.G.M. (Utrecht University) [33]. Anthropogenic land-use estimates for the Holocene; HYDE 3.2. DANS. Legend displays the original classification of the anthromes (with numbers) as proposed by Ellis and Ramankutty [34]. The legend includes the most represented anthromes as visible in the map (map elaborated with ArcGIS).
Pastoral areas in Fezzan (area 1 in Figure 1) according to ethnographic sources [35-37]: (a) the five areas discussed in this paper, key: 1-Wadi Shati, 2-Wadi el Ajal, 3-Wadi Berjuj, 4-Wadi Hikma, and 5-Wadi Tanezuft; (b) in relation to the Aridity Index values; (c) superimposed to rangeland values; and (d) superimposed to grazing values. Legend in (c,d) displays the land use according to Klein [33]. Spatial resolution 5 arc-minutes (maps elaborated with ArcGIS).
The reconstruction of land use practices in hyper-arid Saharan Africa is often hampered by the accuracy of the available tools and by unconscious biases that see these areas as marginal and inhospitable. Considered that this has been for a long time the living space of pastoral mobile communities, new research is showing that agriculture might have been more important in these areas than previously thought. In this paper, after a review of present-day land use strategies in Saharan Africa, we show how ethnographic and ethnoarchaeological data can offer us a different point of view and help in better defining land use and food production strategies in this area. Ultimately, these insights can be integrated into the ongoing efforts to reconstruct past land use globally.
A map of Africa, including Madagascar and southern Arabia, highlighting the distribution of karst regions through the mapping of carbonates and evaporites (data provided by The World Karst Aquifer Mapping Project (WOKAM) [3]) and the locations of speleothem records (open circles represent those included in SISAL_v1; triangles represent sites not included in SISAL_v1).
Regional climate and circulation patterns showing the boundaries of the Intertropical Convergence Zone (ICTZ), Congo Air Boundary and Mid-Latitude westerlies (adapted from [80]) and including locations of speleothem records (open circles represent those included in SISAL_v1; triangles represent sites not included in SISAL_v1): (A) January; and (B) July/August.
Modern isoscapes and recent speleothem stable isotope values: (A) speleothem δ 18 O (circles) on interpolated map of Global Network of Isotopes in Precipitation mean annual δ 18 O [153,154]; and (B) speleothem δ 13 C (circles) on modelled plant δ 13 C [155] based on MODIS data [152]. δ 13 C map colours are blank in Africa where there is little or no vegetation and outside of Africa where the model was not run. Speleothem stable isotopes are the mean of the most recent five measurements for each stalagmite growing at any point during the last 2000 years. Speleothem colours are on an identical scale as the modern isoscape for δ 18 O, but divided either side of −6‰ for δ 13 C (based on [156]), as there is substantial fractionation between leaf cover and speleothem calcite, and it has not yet been established how speleothem δ 13 C responds to mixed C3/C4 vegetation above the cave [156,157].
African speleothem isotope variability during the last 12,000 years. All plots show mean δ 18 O in 1000-year bins. Colours indicate positive δ 18 O (purple), negative δ 18 O (green), low mean δ 18 O
Africa spans the hemispheres from temperate region to temperate region and has a long history of hominin evolution. Although the number of Quaternary palaeoclimatic records from the continent is increasing, much of the history of spatial and temporal climatic variability is still debated. Speleothems, as archives of terrestrial hydroclimate variability, can help reveal this history. Here we review the progress made to date, with a focus on the first version of the Speleothem Isotopes Synthesis and AnaLysis (SISAL) database. The geology of Africa has limited development of large karst regions to four areas: along the northern coast bordering the Mediterranean, eastern Africa and the Horn of Africa, southwestern Africa and southern Africa. Exploitation of the speleothem palaeoclimate archives in these regions is uneven, with long histories of research, e.g., in South Africa, but large areas with no investigations such as West Africa. Consequently, the evidence of past climate change reviewed here is irregularly sampled in both time and space. Nevertheless, we show evidence of migration of the monsoon belt, with enhanced rainfall during interglacials observed in northeast Africa, southern Arabia and the northern part of southern Africa. Evidence from eastern Africa indicates significant decadal and centennial scale rainfall variability. In northwestern and southern Africa, precession and eccentricity influence speleothem growth, largely through changing synoptic storm activity.
Proposed evolution of the human trophic level during the Pleistocene. LP-Lower Paleolithic; MP-Middle Paleolithic; UP-Upper Paleolithic; E. hominins-Early hominins, (Australopithecus, Paranthropus). Background and position of primates adapted from [23]. Each line corresponds to the plants and animals' food-source ratio of one mammalian species. Plant specialists and hypercarnivores-mammals that obtain over 70% of their food from plants and animals, respectively. Omnivores-any mammal that obtains food from both plants and animals.
Net caloric return per hour as a function of prey size. Data in [27].
We hypothesize that megafauna extinctions throughout the Pleistocene, that led to a progressive decline in large prey availability, were a primary selecting agent in key evolutionary and cultural changes in human prehistory. The Pleistocene human past is characterized by a series of transformations that include the evolution of new physiological traits and the adoption, assimilation, and replacement of cultural and behavioral patterns. Some changes, such as brain expansion, use of fire, developments in stone-tool technologies, or the scale of resource intensification, were uncharacteristically progressive. We previously hypothesized that humans specialized in acquiring large prey because of their higher foraging efficiency, high biomass density, higher fat content, and the use of less complex tools for their acquisition. Here, we argue that the need to mitigate the additional energetic cost of acquiring progressively smaller prey may have been an ecological selecting agent in fundamental adaptive modes demonstrated in the Paleolithic archaeological record. We describe several potential associations between prey size decline and specific evolutionary and cultural changes that might have been driven by the need to adapt to increased energetic demands while hunting and processing smaller and smaller game.
The dense point cloud from Kastrouli, as classified by the fully automated Classify Points algorithm. Green points are classified as "high vegetation", orange points are classified as "building", and brown points are classified as "ground". Much of the bare earth at the site is incorrectly classified as "building."
Methods of point cloud classification in Agisoft Metashape Professional and the correspond- ing user parameters used to produce optimal DTMs at Kastrouli.
This paper tests the suitability of automated point cloud classification tools provided by the popular image-based modeling (IBM) software package Agisoft Metashape for the generation of digital terrain models (DTMs) at moderately-vegetated archaeological sites. DTMs are often required for various forms of archaeological mapping and analysis. The suite of tools provided by Agisoft are relatively user-friendly as compared to many point cloud classification algorithms and do not require the use of additional software. Based on a case study from the Mycenaean site of Kastrouli, Greece, the mostly-automated, geometric classification tool “Classify Ground Points” provides the best results and produces a quality DTM that is sufficient for mapping and analysis. Each of the methods tested in this paper can likely be improved through manual editing of point cloud classification.
Study area: Chtouka aquifer in the south of Morocco.
gives a spatial overview of the results of the classification for the summer period 2019 based on the Sentinel 2 data from 26 July 2019. The total area of greenhouses was 15,870 ha and of annual crops was 7433 ha.
Average groundwater abstraction in summer 2019.
Difference of the pixel-based classification and the vector dataset by CRTS.
Classification results compared to land use map 2019.
In semi-arid regions that are characterized by large agricultural activities, a high volume of water is needed to cover the water requirements for agricultural production. Due to low precipitation and the associated limited availability of surface water, aquifers often represent the main source of irrigation water in these regions. Especially in coastal aquifers, high groundwater abstraction rates may change the flow dynamics of the aquifer and may lead to saltwater intrusion. In this study, within the framework of German–Moroccan international cooperation, the agricultural areas for the summer period 2019 of the Chtouka coastal aquifer in southern Morocco are classified using optical and multi-spectral Sentinel 2 data. Based on the developed land use maps, the groundwater abstraction for irrigation is then quantified by referring to local farmers’ irrigation practices. Following this approach, the total amount of groundwater abstraction is estimated at 157 million m³ for the summer period 2019 in the Chtouka aquifer.
Diffusion of wet rice farming and archaeological sites in Japan ([8]. Used by permission).
Obsidian from the Motoyashiki site [29].
Occupation calendar at the Motoyashiki site (latter half and final phase of the Jomon period).
Occupation calendar of the Miomote settlement (Early Edo period).
This study was conducted to elucidate the introduction of agriculture and social continuity from the Jomon to the Yayoi period, from an ethnoarchaeological perspective. The Yayoi period has been divided into two types: a broad spectrum economy that relied on many kinds of resources, such as rice, millet, and nuts, and a selective economy that specialised in rice and wild boar. However, it is not clear how the livelihoods shifted from the Jomon to the Yayoi period. In this study, ethnohistorical materials were examined first. Ethnohistorical reference materials gathered worldwide have revealed three relationships between hunter–gatherers and farmers: coexistence, fusion, and assimilation. Focusing on fusion, this study examined situations of hunting, gathering, and fishing, as inferred from ruins of the Late and Final Jomon period, and assessed their relationships with agriculture using ethnohistorical reference materials of the Early Edo period. There were not many social changes caused by the introduction of field farming; however, the introduction of paddy rice cultivation had different effects on society depending on the level of investment in obtaining water from streams and springs and creating irrigation features.
Location of La Guillerma archaeological locality.
Types of modification on LG1 and LG5 sites.
Pits with striae in base. (A) Pit on C. aperea's femur (Id. 3713). (B) Pit and etched appearance on a mammals' tibia (Id. 2005). (C) Pit on a fresh fracture surface (Id. 340). (D) Pit on a coypu radius (Id. 5519).
Traces on bones from LG1 and LG5 sites. * Diameter; ** Affected area.
The La Guillerma archaeological locality is located in the northeast sector of Buenos Aires province (Argentina). Two of its sites (LG1 and LG5), dated between ca. 1400- and 600-years BP, have a great amount of faunal remains including deer, rodents, fish and small birds that are subjected to taphonomic agents and processes (e.g., weathering, manganese, roots). Previous studies have shown osteophagic behaviour in different insects (e.g., Coleoptera, Blattodea). In this paper, we evaluate their incidence on La Guillerma faunal assemblage. We performed an analysis on marks that were identified in bone remains of various taxa and applied the criteria for identifying bone alteration by insects (i.e., by measuring each trace and comparing them with the types of insect marks described in the literature). Fifteen specimens (LG1 = 6 and LG5 = 9) exhibited different types of modifications (e.g., pits with striae in base, pits with emanating striae, striations) that are related to the action of insects. Although the proportion of affected bones is low in relation to the total sample, we highlight our study as the first detailed analysis of insect marks on archaeological bones from Argentina. We also emphasize the significance of addressing insect-produced modifications on Argentinean archaeological sites.
Snow avalanches cause many fatalities every year and damage local economies worldwide. The present-day climate change affects the snowpack and, thus, the properties and frequency of snow avalanches. Reconstructing snow avalanche records can help us understand past variations in avalanche frequency and their relationship to climate change. Previous avalanche records have primarily been reconstructed using dendrochronology. Here, we investigate the potential of lake sediments to record snow avalanches by studying 27 < 30-cm-long sediment cores from Kenai Lake, south-central Alaska. We use X-ray computed tomography (CT) to image post-1964 varves and to identify dropstones. We use two newly identified cryptotephras to update the existing varve chronology. Satellite imagery is used to understand the redistribution of sediments by ice floes over the lake, which helps to explain why some avalanches are not recorded. Finally, we compare the dropstone record with climate data to show that snow avalanche activity is related to high amounts of snowfall in periods of relatively warm or variable temperature conditions. We show, for the first time, a direct link between historical snow avalanches and dropstones preserved in lake sediments. Although the lacustrine varve record does not allow for the development of a complete annual reconstruction of the snow avalanche history in the Kenai Lake valley, our results suggest that it can be used for long-term decadal reconstructions of the snow-avalanche history, ideally in combination with similar records from lakes elsewhere in the region.
Recent decades of warmer climate have brought drying wetlands and falling lake levels to southern Alaska. These recent changes can be placed into a longer-term context of postglacial lake-level fluctuations that include low stands that were as much as 7 m lower than present at eight lakes on the Kenai Lowland. Closed-basin lakes on the Kenai Lowland are typically ringed with old shorelines, usually as wave-cut scarps, cut several meters above modern lake levels; the scarps formed during deglaciation at 25–19 ka in a kettle moraine topography on the western Kenai Lowland. These high-water stands were followed by millennia of low stands, when closed-basin lake levels were drawn down by 5–10 m or more. Peat cores from satellite fens near or adjoining the eight closed-basin lakes show that a regional lake level rise was underway by at least 13.4 ka. At Jigsaw Lake, a detailed study of 23 pairs of overlapping sediment cores, seismic profiling, macrofossil analysis, and 58 AMS radiocarbon dates reveal rapidly rising water levels at 9–8 ka that caused large slabs of peat to slough off and sink to the lake bottom. These slabs preserve an archive of vegetation that had accumulated on a lakeshore apron exposed during the preceding drawdown period. They also preserve evidence of a brief period of lake level rise at 4.7–4.5 ka. We examined plant succession using in situ peat sequences in nine satellite fens around Jigsaw Lake that indicated increased effective moisture between 4.6 and 2.5 ka synchronous with the lake level rise. Mid- to late-Holocene lake high stands in this area are recorded by numerous ice-shoved ramparts (ISRs) along the shores. ISRs at 15 lakes show that individual ramparts typically record several shove events, separated by hundreds or thousands of years. Most ISRs date to within the last 5200 years and it is likely that older ISRs were erased by rising lake levels during the mid- to late Holocene. This study illustrates how data on vegetation changes in hydrologically coupled satellite-fen peat records can be used to constrain the water level histories in larger adjacent lakes. We suggest that this method could be more widely utilized for paleo-lake level reconstruction.
Marine geophysical surveys were carried out at the underwater site in the south-western sector of the Eastern Harbor of Alexandria, opposite to the Egyptian Sea Scout Club. Survey works aimed to detect and study the surface and subsurface geomorphological changes caused by historic sea-level rise and natural hazards, by integrating the results of high-resolution geophysical mapping for the seafloor textures and the subsurface layers with previously published core data and sea-level records, the survey works employed echo-sounder, side scan sonar, and sub-bottom profiler. Acoustic data were ground-truthed using an ROV camera and sediment grab sampler. Results of bathymetric mapping and sonar imaging outlined two breakwaters and quay corresponding to a submerged ancient port; also, sediment types were classified according to variation in the magnitude of the backscattered intensities. Interpretation of sub-bottom profiles illustrated the depositional sequence of the topmost sedimentary layers where the sediment thicknesses were thickened by rates that perfectly matched with the recorded sea-level rise rate during the last two millennia, as indicated by isopach maps. Anthropogenic activities were noticed in particular outcropping areas on the sub-bottom profiles. The results explained the role of natural hazards and sea-level rise in changing the geomorphology of the coastline and seabed features.
Eight anatomically and taxonomically different finds are presented in this paper, and they belong to four taxa: woolly mammoth (Mammuthus primigenius), giant deer (Megaloceros giganteus), red deer (Cervus elaphus), and dog (Canis familiaris). All specimens represent allochthonous Late Pleistocene and Holocene animal remains, and all were dredged during the gravel exploitation at the Sekuline site near Molve (Podravina region, SW Pannonian basin, NE Croatia). Mammoth remains (bone and tusk fragments) were radiocarbon dated, and these are the first absolute dates on mammoths in Croatia. One upper last left deciduous premolar (dP4 sin.) also belongs to the same species. Ascribed to a dog is one well-preserved skull with a peculiar abscess scar on the maxillary bone as the result of an inflammatory process on the carnassial (P4) premolar. The Late Pleistocene cervid remains are giant deer, while the other cervid finds were determined to be red deer of the Holocene age. Morphometrical and taphonomical data are presented for each specimen. Such fossil and recent bone/tooth aggregates are characteristic of fluvial deposits and selective collecting. Although lacking stratigraphic provenance, these finds help to fulfil the gaps in palaeoenvironmental, palaeoecological, and palaeoclimate reconstructions of Podravina and its neighbouring areas.
The Foxhall Road site, showing the extent of the palaeolake deposits (shaded).
Quaternary sites at Clacton-on-Sea, showing the footprint of the complex of interglacial channels (a). Part (b) is an enlargement of the area around Marine Parade West, showing the locations of the recent development sites that have yielded new data and the various temporary exposures in the West Cliff during the 1980s. Part (c) shows the section through the channel derived from those exposures and neighbouring boreholes.
Mammalian teeth from the beach recharge between Clacton and Holland-on-Sea. Top row, mammoth (Mammuthus sp.); middle, woolly rhinoceros (Coelodonta antiquitatis); bottom row, horse (Equus sp.) Photos: John Ratford.
Equivalent doses and luminescence ages. ('n' is the number of aliquots).
The sequence at Foxhall Road, according to different authors.
This paper presents an updated geological reconstruction of the Quaternary evolution of the River Thames at its downstream extremities, close to the North Sea coast, based on new data from multi-disciplinary and citizen-science sources. In this area, the interaction of the Thames with the MIS 12 (Anglian) glaciation is an important part of the Quaternary archive. The Anglian ice sheet, which reached parts of north and east London, was responsible for diverting the Thames southwards into its present course, although the footprint of the maximum ice sheet(s) does not reach the North Sea coast south of Hollesley, Suffolk. Further south, the coastal zone hosts pre-Anglian and early Anglian river-terrace deposits of the pre-diversion Thames system, superimposed upon which are products of later post-Anglian rivers, of both Middle and Late Pleistocene age. On the peninsula between the Stour and Blackwater–Colne estuaries, the lowest and most recent terrace of the pre-diversion Thames includes evidence directly pertaining to the glacial disruption event, for which geochronological data are reported here for the first time. The first post-diversion terrace of the Thames also reaches this peninsula, the river having essentially re-joined its original valley before crossing the alignment of the modern coastline. This terrace passes beneath Clacton-on-Sea, where it includes the type locality of the Clactonian Palaeolithic Industry. The area of interest to this paper, in NE Essex and southern Suffolk, includes a number of interglacial and Palaeolithic sites, the data from which assist in constraining the chronostratigraphy of the sequence. In some cases, there has been uncertainty as to whether these sites represent pre-Anglian environments and hominin occupations, part of the palaeo-Thames sequence, or whether they are the product of later post-Anglian streams, formed after the Thames had migrated southwards. This paper compiles evidence from a wide range of recent sources, including developer-funded archaeological appraisal and citizen-science activities, to explore and update the evidence from sites at Ipswich, Upper Dovercourt and Thorpe-le-Soken, as well as a number of localities associated with the Clacton Channel Deposits (host to the type-Clactonian), amongst others. The resulting new data are placed within the wider context of the Quaternary fluvial archives in southern Britain, with a discussion of how disparate sources of information, including the work of citizen scientists, have contributed.
Map showing the location of key sites mentioned in the text and the five biogeographic zones of Colombia: Caribbean, Pacific, Andean, Orinoco, and Amazon.
(a) Aerial photograph of the prominent Cerro Azul outcrop; (b) Painted panel of rock art at Cerro Azul.
Stratigraphic profile of Excavation 1 from Cerro Azul showing strata (strata labeled with Roman numerals) and AMS radiocarbon dates. Dashed lines indicate the sampling column for phytolith analysis. For full profile drawing and description see Morcote-Rios et al. [18].
Diagram of macrobotanical remains from Excavation Unit 1 from Cerro Azul. Macrobotanical remains were analyzed from arbitrary 5 cm levels collected during excavation. Data are presented by depth below surface. Reprinted from Morcote-Rios et al. [18], with permission from Elsevier. Syagrus orinocensis, Astrocaryum chambira, A. maripa and A. racemose have the highest representation, while Euterpe precatoria, Mauritia flexuosa, Oenocarpus bataua and O. minor are present in lower quantities. Carbonized macro remains of Brosimum lactescens (Moraceae) are present in all strata, indicating its continued use as an edible. Seeds belonging to the families Araceae, Euphorbiaceae, Humiriaceae, and Poaceae are associated with more research human activity in the upper stratigraphy. A total of 2388 fragments of woody charcoal were also recovered, likely representing various domestic activities at the rock shelter, including heat generation and food preparation. Fragments corresponding to palm trunks may indicate their use as fuel. The palm family is also the best represented in the phytolith assemblage (Figure 5). Mauritia flexuosa and the groups Astrocaryum-Bactris, Euterpe-Oenocarpus, as well as other palmae indet. (globular echinate) category, being the most abundant. Trapezoidal, rectangular, bilobate phytoliths, and bulliform cells, diagnostic of grasses, indicate open areas were present in close proximity to the site. Other identified taxa of note in the phytolith assemblage include Heliconia sp. Edible rhizomes of Heliconia hirsute are still consumed in the Amazon, while leaves of H. hirsuta are used in the construction of baskets. Phytoliths of the multi-purpose Phenakospermum guyannense (Strelitziaceae) were also recovered. The seeds of the species are edible and its leaves are used in campsite construction by the modern Nukak [86,98,99]. Phytoliths from arboreal and herbaceous dicots are present throughout the archaeological sequence (indet. morphotypes). Unfortunately, these groups do not produce diagnostic morphotypes to allow greater taxonomic resolution.
The role of plants in early human migrations across the globe has received little attention compared to big game hunting. Tropical forests in particular have been seen as a barrier for Late Pleistocene human dispersals due to perceived difficulties in obtaining sufficient subsistence resources. Archaeobotanical data from the Cerro Azul rock outcrop in the Colombian Amazon details Late Pleistocene plant exploitation providing insight into early human subsistence in the tropical forest. The dominance of palm taxa in the assemblage, dating from 12.5 ka BP, allows us to speculate on processes of ecological knowledge transfer and the identification of edible resources in a novel environment. Following the hypothesis of Martin Jones from his 2009 work, “Moving North: archaeobotanical evidence for plant diet in Middle and Upper Paleolithic Europe”, we contend that the instantly recognizable and economically useful palm family (Arecaceae) provided a “gateway” to the unknown resources of the Amazon forest.
It has recently been argued that pre-Columbian societies in the greater Amazon basin during the Late Holocene were subject to “adaptive cycling”. In this model, cultures practicing “intensive” land use practices, such as raised field agriculture, were vulnerable to perturbations in hydroclimate, whereas “extensive” land use patterns, such as polyculture agroforestry, are viewed as more resilient to climate change. On the basis of radiocarbon data, the relative rise and fall of late pre-Columbian cultures and their inferred patterns of land use in six regions are highlighted to exemplify this model. This paper re-examines the radiocarbon evidence marshalled in favour of adaptive cycling, demonstrating that alleged temporal patterning in these data are overwhelmingly likely due to a combination of sampling effects, lack of statistical controls, and unacknowledged uncertainties that are inherent to radiocarbon dating. The outcome of this combination of factors seriously limits the possibility of cross-referencing archaeological data with palaeo-ecological and -climatological data without controlling for these effects, undermining the central archaeological pillar in support of adaptive cycling in Amazonia. This paper illustrates examples of such mitigation measures and provides the code to replicate them. Suggestions for how to overcome the serious limitations identified in the Late Holocene radiocarbon record of Amazonia are presented in the context of ongoing debates on inferring climatic causation in archaeological and historical datasets.
Speleothem oxygen isotope records from the Caribbean, Central, and North America reveal climatic controls that include orbital variation, deglacial forcing related to ocean circulation and ice sheet retreat, and the influence of local and remote sea surface temperature variations. Here, we review these records and the global climate teleconnections they suggest following the recent publication of the Speleothem Isotopes Synthesis and Analysis (SISAL) database. We find that low-latitude records generally reflect changes in precipitation, whereas higher latitude records are sensitive to temperature and moisture source variability. Tropical records suggest precipitation variability is forced by orbital precession and North Atlantic Ocean circulation driven changes in atmospheric convection on long timescales, and tropical sea surface temperature variations on short timescales. On millennial timescales, precipitation seasonality in southwestern North America is related to North Atlantic climate variability. Great Basin speleothem records are closely linked with changes in Northern Hemisphere summer insolation. Although speleothems have revealed these critical global climate teleconnections, the paucity of continuous records precludes our ability to investigate climate drivers from the whole of Central and North America for the Pleistocene through modern. This underscores the need to improve spatial and temporal coverage of speleothem records across this climatically variable region.
Location of the Gault site and the Debra L. Friedkin site in central Texas. Reproduced from [126]; courtesy Michael B. Collins.
Gault Assemblage artifacts: (A-D,F,L) bifaces; (E) blade core; (G) quartz projectile point; (H-J) projectile points; (K) projectile-point tip; (M,V,W) blades; (N) unifacial tool; (O,T) gravers; (P) discoidal biface; (Q) end scraper; (R-U) modified-flake tools; (X,Y) lanceolate projectile points (units in cm). Reproduced from [126]; courtesy Michael B. Collins.
Bivariate plot of two relative warps, or principal components, for 241 Clovis points from various regions of North America. Red circles indicate points from the West, and green circles indicate points from the East. The four images display the shape space defined by the first two relative warps. The upper point is from the Southwest (Arizona), the point at the right is from the Northwest (Idaho), the lower point is from the Northeast (Maine), and the point at the left is from the Mid-Atlantic (Pennsylvania). Reproduced with permission from [159]; figure by Briggs Buchanan.
The timing of human entrance into North America has been a topic of debate that dates back to the late 19th century. Central to the modern discussion is not whether late Pleistocene-age populations were present on the continent, but the timing of their arrival. Key to the debate is the age of tools—bone rods, large prismatic stone blades, and bifacially chipped and fluted stone weapon tips—often found associated with the remains of late Pleistocene fauna. For decades, it was assumed that this techno-complex—termed “Clovis”—was left by the first humans in North America, who, by 11,000–12,000 years ago, made their way eastward across the Bering Land Bridge, or Beringia, and then turned south through a corridor that ran between the Cordilleran and Laurentide ice sheets, which blanketed the northern half of the continent. That scenario has been challenged by more-recent archaeological and archaeogenetic data that suggest populations entered North America as much as 15,300–14,300 years ago and moved south along the Pacific Coast and/or through the ice-free corridor, which apparently was open several thousand years earlier than initially thought. Evidence indicates that Clovis might date as early as 13,400 years ago, which means that it was not the first technology in North America. Given the lack of fluted projectile points in the Old World, it appears certain that the Clovis techno-complex, or at least major components of it, emerged in the New World.
Archaeological excavations at the Cueva del Medio performed during the 1980s and 1990s yielded an important record of both faunal and stone tool remains, as well as data, to discuss issues that occurred during the Terminal Pleistocene. Due to that, the shaped Paleoamerican artifacts collected in the author’s excavations were partially informed. The present article provides unpublished data on the field-work, the results of a techno-morphological analysis of the stone tools, and considerations about early hunter-gatherer societies along with their regional paleo-environmental interactions, as well other topics regarding the regional archaeological process during the last millennium of the Pleistocene. Findings from there have been extremely useful for discussing diverse paleo-ecological and archaeological topics and have extended the knowledge and discussions about different Pleistocene scientific issues, mainly related with flora, fauna, and the colonization of southern Patagonia.
Global atmospheric warming is causing physical and biotic changes in Earth’s high mountains at a rate that is likely unprecedented in the Holocene. We summarize changes in the presently glacierized mountains of northwest North America, including a rapid and large reduction in glacier ice and permafrost, a related increase in slope instability and landslides, river re-routing and other hydrological changes, and changing aquatic ecosystems. Atmospheric greenhouse gas concentrations continue to rise and will likely do so for at least the next several decades, if not longer, and mountains will continue to warm, perhaps reaching temperatures up to several degrees Celsius warmer than present over the remainder of this century. As a result, the rate of physical and biotic changes documented in this paper is very likely to dramatically increase and transform high-mountain environments.
(A) Satellite image (norgeskart.no accessed 29 April 2022) of Lake Jøkelvatnet and the Langfjordjøkelen glacier with inset map of Fennoscandia. (B) View looking south towards the glacier from the northern outlet of the lake. (C) View looking north over the lake from near the glacier. Photographs taken by I. G. Alsos in July 2021. (D) Topographic map (norgeskart.no) of the catchment and lake bathymetry showing the coring location of JØP-112.
Disentangling the effects of glaciers and climate on vegetation is complicated by the confounding role that climate plays in both systems. We reconstructed changes in vegetation occurring over the Holocene at Jøkelvatnet, a lake located directly downstream from the Langfjordjøkel glacier in northern Norway. We used a sedimentary ancient DNA (sedaDNA) metabarcoding dataset of 38 samples from a lake sediment core spanning 10,400 years using primers targeting the P6 loop of the trnL (UAA) intron. A total of 193 plant taxa were identified revealing a pattern of continually increasing richness over the time period. Vegetation surveys conducted around Jøkelvatnet show a high concordance with the taxa identified through sedaDNA metabarcoding. We identified four distinct vegetation assemblage zones with transitions at ca. 9.7, 8.4 and 4.3 ka with the first and last mirroring climatic shifts recorded by the Langfjordjøkel glacier. Soil disturbance trait values of the vegetation increased with glacial activity, suggesting that the glacier had a direct impact on plants growing in the catchment. Temperature optimum and moisture trait values correlated with both glacial activity and reconstructed climatic variables showing direct and indirect effects of climate change on the vegetation. In contrast to other catchments without an active glacier, the vegetation at Jøkelvatnet has displayed an increased sensitivity to climate change throughout the Middle and Late Holocene. Beyond the direct impact of climate change on arctic and alpine vegetation, our results suggest the ongoing disappearance of glaciers will have an additional effect on plant communities.
Abbreviated pollen percentage diagram for the last 200 year BP from the Cosapilla 0016-B core from a peatland in the semi-arid Andes of northern Chile.
Detrended correspondence analysis (DCA) of pollen zones of Cosapilla 0016-B core from a peatland in the semi-arid Andes of northern Chile.
Radiocarbon ages of the Cosapilla 0016-B core from a peatland in the semi-arid Andes of northern Chile. The modeled ages (mean and standard deviation) are the result of a probabilistic age-depth model.
The European conquest of the New World produced major socio-environmental reorganization in the Americas, but for many specific regions and ecosystems, we still do not understand how these changes occurred within a broader temporal framework. In this paper, we reconstruct the long-term environmental and vegetation changes experienced by high-altitude wetlands of the southcentral Andes over the last two millennia. Pollen and charcoal analyses of a 5.5-m-long core recovered from the semi-arid puna of northern Chile indicate that while climatic drivers influenced vegetation turnaround, human land use and management strategies significantly affected long-term changes. Our results indicate that the puna vegetation mostly dominated by grasslands and some peatland taxa stabilized during the late Holocene, xerophytic shrubs expanded during extremely dry events, and peatland vegetation persisted in relation to landscape-scale management strategies by Andean pastoralist societies. Environmental changes produced during the post-conquest period included the introduction of exotic taxa, such as clovers, associated with the translocation of exotic herding animals (sheep, cattle, and donkeys) and a deterioration in the management of highland wetlands.
Pollen and forest monitoring data for beech (A-C), annual pollen deposition in three sediment cores (D-F), ring width index from the Müritz and Boizenburg/Schwerin composite (G) and difference in mean July temperature one year ago minus mean the value two years ago (H). Grey bars: reference mast index, dark bars indicate supposed pollen mast years. The pollen index (A) for each year is the sum of all daily means of FAGUS pollen grains per cubic metre of air. Flowering and Pollen and forest monitoring data for beech (A-C), annual pollen deposition in three sediment cores (D-F), ring width index from the Müritz and Boizenburg/Schwerin composite (G) and difference in mean July temperature one year ago minus mean the value two years ago (H). Grey bars: reference mast index, dark bars indicate supposed pollen mast years. The pollen index (A) for each year is the sum of all daily means of Fagus pollen grains per cubic metre of air. Flowering and fructification index (B,C) are assigned by forest monitoring. The reference index is calculated as a mean of pollen, flowering and fructification index. Pollen accumulation rates (PARs) (D-F) are given in pollen grains cm −2 yr −1 .
Pollen and forest monitoring data for spruce (A-C), annual pollen deposition in three sediment cores (D-E). Grey bars: Long bars indicate supposed intense, short bars intermediate flowering years.
Lake surface sediment cores sampled for annual resolution pollen analysis.
Location and details of the pollen trap records used in the present study.
Standard deviation (SD) in the mean flowering index of major forest trees in Germany during the period 1992-2018.
Fossil wood and varved lake sediments allow proxy analysis with exceptionally high, (sub-)annual resolution. Both archives provide dating through ring and layer counting, yet with different accuracy. In wood, counting errors are small and can be eliminated through cross-dating because tree-rings show regionally synchronous patterns. In varved sediments, counting errors are larger and cross-dating is hampered by missing regional patterns in varve parameters. Here, we test whether annual pollen analysis is suited to synchronize varve records. To that end, annual pollen deposition was estimated in three short cores from two lakes in north-eastern Germany for the period 1980–2017 CE. Analysis has focused on Fagus sylvatica and Picea abies, which show the strongest annual variations in flowering (mast). For both tree taxa, annual flowering variations recorded by forest and pollen monitoring are well represented in varved lake sediments, hence indeed allow us to synchronize the records. Some pollen mast events were not recognized, which may relate to sampling uncertainties, redeposition or regional variations in flowering. In Fagus sylvatica, intense flowering limits wood growth in the same year. Peaks in pollen deposition hence correlate with minima in tree-ring width, which provides a link between varved lake sediments and fossil wood.
The collection of papers entitled “Annually Laminated Lake Sediments” illustrates the recent progress made in varved sediment research and highlights the variety of methodological approaches and research directions used. The contributions cover the monitoring of modern sediment fluxes using sediment traps, geochronological and sedimentological analyses of varves, multi-proxy investigations, including geochemical and biological proxies, as well as spatiotemporal analyses based on multi-core studies supported by satellite images. The scientific issues discussed the influences of hydroclimatological phenomena on short-term changes in sediment flux, the relationships between biogeochemical processes in the water column and the formation of varves, the preservation of environmental signals in varves, and possibilities of synchronizing varved records with other high-resolution environmental archives.
Top-cited authors
Fabien Arnaud
  • Université Savoie Mont Blanc
C. Giguet-Covex
  • The University of York
Ran Barkai
  • Tel Aviv University
Franziska A Lechleitner
  • Universität Bern
Laura Parducci
  • Sapienza University of Rome