Palynology,sedimentology and palaeoecology of the late Holocene Dead Sea

Palynological and sedimentological studies were performed at two Holocene profiles in erosion gullies (Ze’elim and Ein Feshkha) which dissect the retreating western shore of the Dead Sea. The aim of the project was to analyse possible links between climate, lithology, and vegetation development. The section in Ze’elim shows both lacustrine and fluvial sediments, whereas sedimentation at Ein Feshkha is predominantly lacustrine. The Ze’elim profile, previously used for paleo-lake reconstruction provides an opportunity to compare climate triggered lake levels as paleo-hydrological indicators and vegetation history by use of palynology. The vegetation development in Ze’elim and Ein Feshkha is influenced by both climate and human impact. The pollen record of Ze’elim begins in the Pottery Neolithic, the section of Ein Feshkha in the Late Bronze Age, both records end in the Middle Ages. The Ze’elim section is characterized by sedimentary hiati between the beginning of the Chalcolithic Period until the Middle Bronze Age and within the Late Bronze Age. Settlement periods during the Middle Bronze Age, Iron Age and Hellenistic–Roman–Byzantine Period are indicated by high values of anthropogenic indicators and/or Mediterranean trees. Collapses of agriculture, which can be related to climate effects, are evident during the Late Bronze Age, during the Iron Age and at the end of the Byzantine Period when the lake level curve indicates arid conditions. A comparison of the two pollen records, from different environments, illustrates a more prominent influence of Mediterranean vegetation and cultivated plants in the pollen diagram of Ein Feshkha. The southern Dead Sea region (at the desert fringe) is more vulnerable to regional climate change.     

Drainage network expansion of the Salagou drainage basin (S. France): an example of relief response to recent climate change?

Continental erosion is known to be strongly controlled by climate but the way by which geomorphological systems respond to climate change still remains poorly understood. Recent numerical modelling suggests that drainage networks are subjected to strong spatial fluctuations but few studies of natural systems have addressed this phenomenon because of the difficulty of documenting the evolution of erosional landscapes. A detailed field analysis has allowed reconstruction of the past topography of a drainage basin located in southern France where remnants of a past landscape are well preserved. A change from a smooth to a present-day dissected landscape is observed and related to a change in the dominant processes of erosion. This evolution is interpreted in terms of fluctuations in drainage network extent in response to a Holocene increase in precipitation.     

Konispol Cave,southern Albania,and correlations with other Aegean caves occupied in the Late Quaternary

Archeological excavations in a karstic cavern on the south facing slopes of the Pindus range, southern Albania, have disclosed a continuous, 4.5 m thick sequence of human occupation since the Mesolithic. In 1994 geoarcheological field work identified nine (9) principal lithostrata that correspond with successive occupations. Sedimentary sequences indicate that during the Mesolithic spring flow was active and produced a pool in the cave's central chamber. This accounts for settlement along the dry western margin of the cave. After 6000 B.P. episodic flushing of Terra Rossa soil from the cave slopes was dominant. Sediments were variously modified or mobilized by weathering, diagenesis and human agency. These changes are correlated to the chronology and contribute to a limited reconstruction of site formation process. Comparison of sediment stratigraphy with an earlier study of magnetostratigraphy verifies an inferred moist pulse of the Early Holocene/Mesolithic and a turn to warmer/drier conditions during the Middle Holocene/Neolithic. The Konispol sequence is compared to cave chronologies in neighboring Epirus (Kastritsa and Klithi) and to Franchthi in southern Greece. Sedimentation patterns reveal that these caves were initially occupied at the same time (Late Pleniglacial) and that during deglaciation there was a general hiatus in deposition (15,000–10,000 B.P.). Early Holocene moisture phases correspond to an increase in sedimentation during the Neolithic when the caves were intensely utilized. © 1998 John Wiley & Sons, Inc.     

Contrasting patterns of precipitation seasonality during the Holocene in the south‐ and north‐central Mediterranean

Pollen‐based quantitative estimates of seasonal precipitation from Lake Pergusa and lake‐level data from Lake Preola in Sicily (southern Italy) allow three successive periods to be distinguished within the Holocene: an early Holocene period before ca. 9800 cal a BP with rather dry climate conditions in winter and summer, a mid‐Holocene period between ca. 9800 and 4500 cal a BP with maximum winter and summer wetness, and a late Holocene period after 4500 cal a BP with declining winter and summer wetness. This evolution observed in the south‐central Mediterranean shows strong similarities to that recognized in the eastern Mediterranean. But, it contrasts with that reconstructed in north‐central Italy, where the mid‐Holocene appears to be characterized by a winter (summer) precipitation maximum (minimum), while the late Holocene coincided with a decrease (increase) in winter (summer) precipitation. Maximum precipitation at ca. 10 000–4500 cal a BP may have resulted from (i) increased local convection in response to a Holocene insolation maximum at 10 000 cal a BP and then (ii) the gradual weakening of the Hadley cell activity, which allowed the winter rainy westerlies to reach the Mediterranean area more frequently. After 4500 cal a BP, changes in precipitation seasonality may reflect non‐linear responses to orbitally driven insolation decrease in addition to seasonal and inter‐hemispheric changes of insolation. Copyright © 2011 John Wiley & Sons, Ltd.     

Holocene circum-Mediterranean vegetation changes: Climate forcing and human impact

The Mediterranean climate and its variability depend on global-scale climate patterns. Close correlations appear when comparing Holocene palaeoenvironmental data (lake levels, fluvial activity, Mediterranean surface temperature and salinity, marine sedimentation) with the main stages of the history of the circum-Mediterranean vegetation. They indicate an evolution of the Mediterranean biome controlled by the climate and emphasize the teleconnections between the climate of the Mediterranean area and the global climatic system. In the circum-Mediterranean area, the Holocene can be divided into three periods: a lower humid Holocene (11 500–7000 cal BP) interrupted by dry episodes; a transition phase (7000–5500 cal BP) during which occurred a decrease in insolation as well as the installation of the present atmosphere circulation in the northern hemisphere; and an upper Holocene (5500 cal BP—present) characterized by an aridification process. Throughout the Holocene, humans used and modified more or less strongly the environment but the climatic changes were the determining factors of the evolution of the Mediterranean biome. Societies had to adapt to natural environmental variations, their impact on the environment increasing the ecological consequences of the global changes.     

Fluvial system response to external forcing and human impact – Late Pleistocene and Holocene fluvial dynamics of the lower Guadalete River in western Andalucía (Spain)

The 170 km long river course of the Guadalete River (western Andalucía) provides an excellent record of Late Pleistocene and Holocene fluvial sedimentation dynamics. Furthermore, its floodplain sediments are very well suited to describe geomorphic changes forced by climate fluctuations, sea‐level changes, tectonic influences and human activity. Multiproxy investigations were based on field mapping and the study of 18 profile sections, mainly including sedimentological characterisation, soil‐chemical analyses and radiocarbon dating of 34 samples. Findings were complemented by drillings and electrical resistivity tomography. The lowermost 50 km of the river section are divided into an upper and lower part (each 25 km long), based on different sediment preservation conditions. The boundary corresponds to the disappearance of the Late Pleistocene river terrace. Significant floodplain aggradation occurred at around 10 000 cal. years BP, while dynamics were strongly affected by sea‐level fluctuations until the early Holocene. Furthermore, sedimentation starting at 8000, 6100, 4600, 2200, 900 and 400 cal. years BP is related to enhanced fluvial dynamics due to environmental stress that presumably was triggered by climate fluctuations, that is, aridification. However, the strongest intensity of sedimentation at 400 cal. years BP points to climate anomalies in the course of the Little Ice Age. In contrast, several periods of stability associated with alluvial soil formation took place during the Bølling and Allerød interstadials, prior to 8000, 6100 and 5100, and after 4300 and 2000 cal. years BP. The anthropogenic signal in floodplain evolution is not clearly distinguishable from that of climate. However, human land use had the potential to amplify geomorphic processes, especially during periods of climate deteriorations that caused increasing stress on the environment.     

Holocene climate and cultural evolution in late prehistoric-early historic West Asia

The precipitation climatology and the underlying climate mechanisms of the eastern Mediterranean, West Asia, and the Indian subcontinent are reviewed, with emphasis on upper and middle tropospheric flow in the subtropics and its steering of precipitation. Holocene climate change of the region is summarized from proxy records. The Indian monsoon weakened during the Holocene over its northernmost region, the Ganges and Indus catchments and the western Arabian Sea. Southern regions, the Indian Peninsula, do not show a reduction, but an increase of summer monsoon rain across the Holocene. The long-term trend towards drier conditions in the eastern Mediterranean can be linked to a regionally complex monsoon evolution. Abrupt climate change events, such as the widespread droughts around 8200, 5200 and 4200 cal yr BP, are suggested to be the result of altered subtropical upper-level flow over the eastern Mediterranean and Asia.The abrupt climate change events of the Holocene radically altered precipitation, fundamental for cereal agriculture, across the expanse of late prehistoric-early historic cultures known from the archaeological record in these regions. Social adaptations to reduced agro-production, in both dry-farming and irrigation agriculture regions, are visible in the archaeological record during each abrupt climate change event in West Asia. Chronological refinement, in both the paleoclimate and archaeological records, and transfer functions for both precipitation and agro-production are needed to understand precisely the evident causal linkages.     

晚冰期以来青藏高原降水序列集成重建

选取青藏高原36条(34个地点)由孢粉已重建的降水序列(8条)和化石孢粉谱(28条),分别采用直接提取和现代类比法获得1852个具有年代的定量降水数据,以高原4个分区为单位,建立青藏高原晚冰期以来古降水数据集。构建分区古降水空间模拟-多区面积加权的集成方法,即借助GIS分析,基于现代高原降水空间分布的地理因子模拟,集成重建晚冰期以来高原古降水序列。结果表明:16~12 ka B.P.,高原总体降水量较少,其中16 ka B.P.不到200 mm,约为现代降水量的一半,15~13 ka B.P.后降水显著增长,较前期上升70 mm;13~12 ka B.P.,又跌至220 mm,较现代低100 mm。进入全新世后,降水量迅速增长,降水在全新世早期的9.2~8.7 ka B.P.即达到最大值,高出现代70 mm,9.2~5.0 ka B.P.为全新世湿润期,平均高出现代50 mm;5 ka B.P.之后,降水波动较小,与现代基本持平。集成降水与其他高低分辨率环境记录有很好的可比性,说明集成序列有很好的代表性和一定的准确性。此外,高原降水变化区域差异明显,全新世最大降水呈现出西早东晚,西南季风(ISM)区早于东南季风(EASM)区的特点,高原西部和南部全新世早期9 ka B.P.左右即达极大值,而高原东缘迟至全新世中期的8.0~7.5 ka B.P.;降水增加最为明显的是高原西北部,最盛期降水约高出为现代的1倍,高原东部和南部现季风控制区域,只比现代高出0.2倍。     

Flood frequencies reveal Holocene rapid climate changes (Lower Moulouya River,northeastern Morocco)

Current high‐resolution palaeoenvironmental records reveal short‐term Holocene coolings. One of these major Holocene rapid climate changes occurred between 3.2 and 2.7 cal. ka BP. The sensitivity of river systems vis‐à‐vis slight and short‐term Holocene climatic variations is a subject of controversy in the scientific community. In this paper, we present a 4.0 to 1.4 cal ka BP palaeoflood record from the Lower Moulouya River (northeastern Morocco) to demonstrate the high sensitivity of semiarid rivers in the southwestern Mediterranean towards Holocene environmental changes. The Lower Moulouya flood deposits are characterised by thick, well‐stratified, predominantly clayey to silty overbank fine sediments. These cohesive sediments show evidence of excellent preservation conditions against fluvial erosion and contain a continuous record of mid to late Holocene flood sequences. The Moulouya palaeoflood record can be interpreted in the context of regional and global high‐resolution proxy data, revealing a strong coupling with Holocene rapid climate changes. The centennial‐scale Moulouya palaeohydrological history will be discussed with palaeoenvironmental data from the same record (palaeomagnetics, sedimentary charcoal record, anthracological analyses, snail analyses) to generate new ideas about the mid to late Holocene hydrological cycle in the southwestern Mediterranean. The deduced features of pronounced Lower Moulouya flooding and the decreased fire recurrence during Holocene cooling remain somewhat inconsistent with the interpretation of other palaeohydrological and paleaoecological records from the southwestern Mediterranean. However, enhanced Lower Moulouya flood frequencies between 3.2 and 2.7 cal. ka BP agree with increased floodplain aggradation in other major river systems of Mediterranean North Africa. Copyright © 2009 John Wiley & Sons, Ltd.     

Lateglacial to Holocene rapid crater infilling of a MIS 2 maar volcano (West‐Eifel Volcanic Field,Germany): environmental history and geomorphological feedback mechanisms

We document the Lateglacial to Holocene sedimentation and vegetation history of a small, infilled crater landform in the West‐Eifel Volcanic Field (WEVF; western Germany). We analysed geomorphological landform change, sedimentological and geochronological data, pollen, and plant macrofossils of a 16‐m‐long sediment core from the Eichholz Maar (EHM). The EHM erupted between ～20 and 15 ka ago (MIS 2). Lacustrine siliclastic infilling was completed about 7500 years ago. Lateglacial rates of sedimentation are generally 2 to 5 times higher than in other maar lakes of the WEVF. Local factors, therefore, overprint the relative efficacy of the climate‐controlled variance of sedimentation rates at the Lateglacial/Holocene transition. The predominance of local factors relates to inherent geomorphological process–response mechanisms that were triggered by the EHM eruption. Rapid crater infilling and its completion by the mid‐Holocene are attributed to a combination of small storage capacity and geomorphological activity. A late Boreal interval of significant lake‐level fall can, however, be attributed to a period of continental‐scale climate change as recorded in other European lacustrine settings. Our findings highlight the importance of utilizing geomorphological information to reveal the relative significance of local controls as opposed to climate control when investigating small‐sized lake settings with active sediment supply systems.     

Landforms,sediments, soil development,and prehistoric site settings on the Madaba‐Dhiban Plateau,Jordan

This paper examines recurrent spatial patterns of prehistoric sites in relation to landforms, alluvial fills, and soil development in the uplands and valleys of the Madaba and Dhiban Plateaus of Jordan. Mousterian lithics (Middle Paleolithic) are largely found on high strath terraces plateaus, where they are associated with red Mediterranean soils. In valleys, Upper Paleolithic sites are often associated with reworked loess deposits of the Dalala allostratigraphic unit. Epipaleolithic occupations are found stratified in deposits of the Thamad Terrace, and Pre‐Pottery Neolithic and Pottery Neolithic occupations are associated with colluvium mantling the Thamad Terrace. The Tur al‐Abyad Terrace and the Iskanderite alluvial inset are the remnants of middle Holocene floodplains, which were attractive areas for Chalcolithic and Early Bronze Age settlements. Sometime around 4000 B.C., stream incision and further lateral erosion destroyed these floodplains. These historic terraces are underlain by alluvial deposits ranging in age from Roman to Early Islamic periods. The sequence of allostratigraphic units, paleosols, and terraces are the basis for reconstructing phases of fluvial aggradation and stream incision during the past 20,000 years. © 2005 Wiley Periodicals, Inc.     

The last millennia history of detrital sedimentation in the Lower Seine Valley (Normandy,NW France): review

Post‐glacial climate changes and sea‐level fluctuations have strongly influenced N‐W European environments and sedimentation. To these natural events, increasing anthropogenic pressure has to be added. Forest clearance and agricultural development are the main factors responsible for the erosional processes in Northwest Europe. This article analyses Holocene sequences of the Lower Seine Valley (LSV) (Paris Basin) to understand better the origin of detrital and terrigenous input and how much humans have contributed to it. Three main sectors of the LSV are analysed: estuarine, fluvial and tributaries. Since Neolithic times, there are seven erosional phases that can be identified and essentially linked to human pressure. Terra Nova, 00, 000–000, 2010     

Quantifying climatic change through the last glacial–interglacial transition based on lake isotope palaeohydrology from central Turkey

Questions remain as to the nature of climatic change through the last glacial–interglacial transition in the eastern Mediterranean region, particularly the relative contribution of evaporation and precipitation to regional water balance. Here changes in oxygen isotope values through this time period from Eski Acıgöl, a crater lake in central Turkey, are investigated using hydrological and isotope mass balance models. These allow changes in evaporation and precipitation to be quantified and their relative importance evaluated. We show that it is the volumetric flux rate of water passing through the lake system and not the precipitation-to-evaporation ratio per se which controlled the stable isotope record in Eski Acıgöl. Early Holocene precipitation is shown to be much greater than that during both the latter part of the last glaciation and the present day. We test these calculated values against other records in the same region, firstly with other lake records in Anatolia, the Konya basin and Lake Van, and secondly with isotope-inferred palaeo-precipitation data from Soreq cave in Israel. This reveals a contrast between pre- and post-LGM precipitation values in Turkey (wetter and drier, respectively) and also suggests that during the last glacial–interglacial transition there was a more marked precipitation gradient than at present between northern/interior and southern/coastal parts of the eastern Mediterranean region.     

Holocene climate changes in southern Greenland: evidence from lake sediments

A Holocene lake sediment record is presented from Lake N14 situated on Angissoq Island 15 km off the main coast of southern Greenland. The palaeoclimatic development has been interpreted on the basis of flux and percentage content of biogenic silica, clastic material, organic material and sulphur as well as sedimentation rate, moss content and magnetic susceptibility. A total of 43 radiocarbon dates has ensured a reliable chronology. It is argued that varying sediment composition mainly reflects changing precipitation. By analogy with the present meteorological conditions in southern Greenland, Holocene climate development is inferred. Between 11 550 and 9300 cal. yr BP temperature and precipitation increase markedly, but this period is climatically unstable. From 9300 yr BP conditions become more stable and a Holocene climatic optimum, characterised by warm and humid conditions, is observed from 8000 to 5000 cal. yr BP. From 4700 cal. yr BP the first signs of a climatic deterioration are observed, and from 3700 cal. yr BP the climate has become more dry and cold. Superimposed on the climatic long‐term trend is climate variability on a centennial time‐scale that increases in amplitude after 3700 cal. yr BP. A climatic scenario related to the strength and position of the Greenland high‐pressure cell and the Iceland low‐pressure cell is proposed to explain the Holocene centennial climate variability. A comparison of the Lake N14 record with a terrestrial as well as a marine record from the eastern North Atlantic Ocean suggests that the centennial climate variability was uniform over large areas at certain times. Copyright © 2004 John Wiley & Sons, Ltd.     

Late Quaternary mammalian zoogeography of eastern Washington

The late Quaternary mammalian zoogeographic history of eastern Washington as revealed by archaeological and paleontological research conforms to a set of past environmental conditions inferred from botanical data. During the relatively cool and moist late Pleistocene and early Holocene, Cervus cf. elaphus, Ovis canadensis, Vulpes vulpes, Martes americana, Alopex lagopus, and perhaps Rangifer sp., taxa with ecological preferences for mesic steppe habitats, were present in the now xeric Columbia Basin. As the climate became progressively warmer and drier during the late Pleistocene and early Holocene, Antilocapra americana, Onychomys leucogaster, Spermophilus townsendii, and Neotoma cinerea, taxa with ecological preferences for xeric steppe habitats, appear in the Columbia Basin. Bison sp. and Taxidea taxus may have been present in eastern Washington for the last 20,000 yr. Middle and late Holocene records for Oreamnos americanus, Spermophilus columbianus, S. townsendii, Lagurus curtatus, and Urocyon cinereoargenteus in central eastern Washington suggest fluctuations in the ranges of these taxa that conform to a middle Holocene period of less effective precipitation and a ca. 3500-yr-old period of more effective precipitation before essentially modern environmental conditions prevailed.     

湖北省土壤侵蚀景观空间异质性及驱动因子分析

地域分异是地球表层大小不等、内部具有一定相似性地段之间的相互分化以及由此产生的差异。为了研究不同区位土壤侵蚀问题，从土壤生态景观及系统论出发，运用地质学、地理学、景观生态学、环境学的理论和研究方法，研究湖北省土壤侵蚀景观空间格局及其驱动因子，使土壤侵蚀问题研究提高到一个新的水平。湖北省土壤侵蚀景观具有南北分带、东西分区，为一不对称的断块一环组合，土壤流呈现向长江、江汉盆地中心轴带辐聚、单流向特点。景观空间异质性形成的首要驱动因子是大地构造背景，以房县一襄樊一广济断裂带为界，南北两侧地壳物质组成和构造发展史存在较明显的差异，现代气候带、降雨量、温热程度及土地利用等差异，造成了湖北省区域土壤地理、土壤生态的分异，形成湖北省土壤生态带、区具有南北分带，东西分区的宏观格局；其次大兴安岭一武陵山深部构造陡变带两侧新构造运动强度差异、大别造山带构造强烈隆升，导致土壤侵蚀强度的西强东弱、南北强中间弱的态势；成土母岩差异性决定了土壤可蚀性的多变；空间上“土壤侵蚀内城区”分布在湖北省的周边地区，经济贫困、管理落后，这一地区的经济水平与水土流失间形成“自反馈作用”，这一现象在我国水土保持、生态建设工作中应该引起重视。     

Drought, vegetation change, and human history on Rapa Nui (Isla de Pascua, Easter Island)

Stratigraphic records from lake sediment cores and slope deposits on Rapa Nui document prehistoric human impacts and natural environmental changes. A hiatus in sedimentation in Rano Raraku suggests that this lake basin dried out sometime after 4090-4410 cal yr BP and refilled only decades to centuries before AD 1180-1290. Widespread ecosystem changes caused by forest clearance by Polynesian farmers began shortly after the end of this drought. Terrestrial sections show a chronology of burning and soil erosion similar to the lake cores. Although changing sediment types and shifts in the pollen rain suggest that droughts occurred earlier in the Holocene, as yet there is no evidence for droughts occurring after AD 1180-1290. The timing of the agricultural colonization of Rapa Nui now seems well established at ca. AD 1200 and it was accompanied by rapid deforestation that was probably exacerbated by the island's small size, its droughty climate, and the rarity of primeval fires. Detailed records of a large interval of Rapa Nui's ecological history remain elusive due to the drought hiatus in the Rano Raraku sediment record. We find no evidence for a “rat outbreak impact” on Rapa Nui's vegetation preceding anthropogenic forest clearance.     

Lacustrine sedimentation in active volcanic settings: the Late Quaternary depositional evolution of Lake Chungará (northern Chile)

Lake Chungará (18°15′S, 69°09′W, 4520 m above sea‐level) is the largest (22·5 km²) and deepest (40 m) lacustrine ecosystem in the Chilean Altiplano and its location in an active volcanic setting, provides an opportunity to evaluate environmental (volcanic vs. climatic) controls on lacustrine sedimentation. The Late Quaternary depositional history of the lake is reconstructed by means of a multiproxy study of 15 Kullenberg cores and seismic data. The chronological framework is supported by 10 ¹⁴C AMS dates and one ²³⁰Th/²³⁴U dates. Lake Chungará was formed prior to 12·8 cal kyr bp as a result of the partial collapse of the Parinacota volcano that impounded the Lauca river. The sedimentary architecture of the lacustrine succession has been controlled by (i) the strong inherited palaeo‐relief and (ii) changes in the accommodation space, caused by lake‐level fluctuations and tectonic subsidence. The first factor determined the location of the depocentre in the NW of the central plain. The second factor caused the area of deposition to extend towards the eastern and southern basin margins with accumulation of high‐stand sediments on the elevated marginal platforms. Synsedimentary normal faulting also increased accommodation and increased the rate of sedimentation in the northern part of the basin. Six sedimentary units were identified and correlated in the basin mainly using tephra keybeds. Unit 1 (Late Pleistocene–Early Holocene) is made up of laminated diatomite with some carbonate‐rich (calcite and aragonite) laminae. Unit 2 (Mid‐Holocene–Recent) is composed of massive to bedded diatomite with abundant tephra (lapilli and ash) layers. Some carbonate‐rich layers (calcite and aragonite) occur. Unit 3 consists of macrophyte‐rich diatomite deposited in nearshore environments. Unit 4 is composed of littoral sediments dominated by alternating charophyte‐rich and other aquatic macrophyte‐rich facies. Littoral carbonate productivity peaked when suitable shallow platforms were available for charophyte colonization. Clastic deposits in the lake are restricted to lake margins (Units 5 and 6). Diatom productivity peaked during a lowstand period (Unit 1 and subunit 2a), and was probably favoured by photic conditions affecting larger areas of the lake bottom. Offshore carbonate precipitation reached its maximum during the Early to Mid‐Holocene (ca 7·8 and 6·4 cal kyr bp ). This may have been favoured by increases in lake solute concentrations resulting from evaporation and calcium input because of the compositional changes in pyroclastic supply. Diatom and pollen data from offshore cores suggest a number of lake‐level fluctuations: a Late Pleistocene deepening episode (ca 12·6 cal kyr BP), four shallowing episodes during the Early to Mid‐Holocene (ca 10·5, 9·8, 7·8 and 6·7 cal kyr BP) and higher lake levels since the Mid‐Holocene (ca 5·7 cal kyr BP) until the present. Explosive activity at Parinacota volcano was very limited between c. >12·8 and 7·8 cal kyr bp . Mafic‐rich explosive eruptions from the Ajata satellite cones increased after ca 5·7 cal kyr bp until the present.     

Micromorphological studies of Greek prehistoric sites: New insights in the interpretation of the archaeological record

Ongoing micromorphological studies in several prehistoric sites of Greece (Theopetra cave, Boila rockshelter, Alonnisos, Drakaina cave, Kouveleiki cave, Lakonis cave complex, and Dispilio lake dwelling) provide new information on the relationship between environmental changes and the cultural history of the sites. The frequent climatic oscillations during the last glacial directly influenced the occupational mode of Theopetra cave and Boila rockshelter in northern Greece. Soil micromorphology may be a promising tool in unraveling differences in the occupational history due to climatic changes among diverse areas of Greece. Some preliminary observations from the Lakonis cave complex, in southern coastal Greece, support the existence of such differences. Evidence brought forward with the micromorphological study of Dispilio lake dwelling and Theopetra cave suggests that during the Holocene, aridification phases evident in the Mediterranean region might have also played a role in the Greek prehistoric settlement pattern. So far, evidence for aridification phases is present for the end of the Mesolithic and probably for part of the Final Neolithic. In several cases, micromorphology has revealed details of the cultural nature of the sites. Questions related to occupational intensity (Theopetra, Lakonis, Kouveleiki, and Drakaina caves), post‐depositional changes and cultural modification of the sediments (Alonnisos, Theopetra, and Drakaina caves), constructions (Theopetra and Drakaina caves), and stratigraphic correlation (Boila) have been satisfactorily addressed along with the analysis of the microstructure of the sediments. © 2002 Wiley Periodicals, Inc.     

Holocene alpine glaciation inferred from lacustrine sediments on northeastern Baffin Island,Arctic Canada

With accelerated melting of alpine glaciers, understanding the future state of the cryosphere is critical. Because the observational record of glacier response to climate change is short, palaeo‐records of glacier change are needed. Using proglacial lake sediments, which contain continuous and datable records of past glacier activity, we investigate Holocene glacier fluctuations on northeastern Baffin Island. Basal radiocarbon ages from three lakes constrain Laurentide Ice Sheet retreat by ca. 10.5 ka. High sedimentation rates (0.03 cm a^?1) and continuous minerogenic sedimentation throughout the Holocene in proglacial lakes, in contrast to organic‐rich sediments and low sedimentation rates (0.005 cm a^?1) in neighbouring non‐glacial lakes, suggest that glaciers may have persisted in proglacial lake catchments since regional deglaciation. The presence of varves and relatively high magnetic susceptibility from 10 to 6 ka and since 2 ka in one proglacial lake suggest minimum Holocene glacier extent ca. 6–2 ka. Moraine evidence and proglacial and threshold lake sediments indicate that the maximum Holocene glacier extent occurred during the Little Ice Age. The finding that glaciers likely persisted through the Holocene is surprising, given that regional proxy records reveal summer temperatures several degrees warmer than today, and may be due to shorter ablation seasons and greater accumulation‐season precipitation. Copyright © 2009 John Wiley & Sons, Ltd.