handaxe and non handaxe assemblages during marine isotope stage 11 in northern europe recent investigations at barnham suffolk uk britain has an important geological environmental and archaeological record for marine isotope stage 11 mis 11 which makes a major contribution to understanding of the human occupation of northern europe new fieldwork at barnham suffolk uk has identified through improved geological resolution the change in assemblages from simple core and flake working to those with handaxe technology the two assemblages are argued to reflect distinct human populations from different source areas in europe the paper examines the european record and puts forward a new model of how the complex mosaic of lithic assemblages reflects local habitual practices during stable environments but changes in climate and environment led to larger scale shifts in population resulting in new human groups arriving in britain

the paleoclimatic record provided by eolian deposition in the deep sea the geologic history of wind the mineral component of pelagic sediment is brought to the deep sea by transport in the wind extraction and analysis of this dust allows estimation of the past aridity of the eolian source region via flux determinations and of the intensity of the transporting winds from grain size data these two parameters the grain size and mass flux of dust vary independently there are three significant sources of modern dust eastern and central asia northwest africa and arabia all in the northern hemisphere as the rainfall associated with the intertropical convergence zone is an effective barrier to southerly transport of dust the northern hemisphere is an order of magnitude more dusty than is the southern an asymmetry that has characterized most of the cenozoic eolian flux data show that most of the northern hemisphere was more arid during glacial maxima with 3 to 5 times as much dust transported during glacial stages than during interglacials only northwestern south america varied in the opposite sense the periodicity of quaternary variation in both eolian flux and eolian grain size data is strongly influenced by the milankovitch cycles of orbital variability wind intensities vary on a shorter time scale than the general 100 kyr cycles of glaciation and general aridity eolian grain sizes display forcing at precessional 19 and 23 kyr tilt 41 kyr and at approximately 30 kyr periodicities as a result the generalization that winds are uniformly stronger during glacial times is not valid whole cenozoic records show that the largest change in dust flux an order of magnitude increase occurred in the northern hemisphere and reflects continental drying associated with the late pliocene onset of northern hemisphere glaciation southern hemisphere eolian records show no sign of paleoclimatic changes in the late pliocene the most important change in cenozoic atmospheric circulation was a severalfold reduction in wind intensity that occurred at the time of the paleocene eocene boundary before then latest cretaceous and paleocene winds were essentially as strong as those of the late cenozoic this shift appears to be one of several climatic responses to a change in the nature and amount of global heat transport at about 55 ma

the oldest handaxes in europe fact or artefact abstract hominin presence is well documented in a number of early pleistocene and early middle pleistocene european localities however the evidence currently available indicates that acheulean handaxes spread in the fluvial basins of western europe during mis 11 400 kyr ago associated with homo heidelbergensis although a number of early middle pleistocene acheulean assemblages have been dated from mis 16 onwards for this reason the magnetostratigraphic dating in southeast spain of two archaeological localities the open air site of solana del zamborino sz and the rock shelter site of cueva negra del estrecho del quipar eq that put back the appearance of handaxes to the early middle pleistocene limit scott and gibert 2009 is of particular interest as the new ages suggest that h heidelbergensis was a contemporary of h antecessor that had the ability to produce levallois debitage and to control fire during the early middle pleistocene transition however we have detected a number of errors in the interpretation of the archaeological assemblage from the first site as well as striking discrepancies with the original faunal lists published for both localities with several large mammal species that are omitted or arbitrarily changed to make the assemblages consistent with the new ages deduced from magnetostratigraphy for this reason we suggest that 1 the finding of reverse polarity in the sediments sampled for paleomagnetism in sz may simply record one of the polarity reversals that took place during the brunhes chron although the use by scott and gibert 2009 of a composite stratigraphic column precludes correlating these levels with a specific reversal and 2 the fauna and tools of eq correspond to the late middle pleistocene sedimentary infillings of this karst site while the samples taken for paleomagnetism belong to a previous sedimentary cycle during the matuyama chron such interpretations would be in better agreement with the age estimates provided by biostratigraphy and also with the currently accepted chronology for the appearance of acheulean industries in western europe

north west european mis 11 malacological successions a framework for the timing of acheulean settlements apart from a few lacustrine sequences in north west europe the marine isotope stage mis 11 interglacial is mainly represented in fluvial sequences and is particularly well preserved in calcareous tufa formations these are favourable for the preservation of a range of fossil groups and several of them have yielded artefacts of acheulean affinity molluscan shells are the most abundant proxy occurring throughout these calcareous deposits they provide a valuable means for reconstructing the palaeoenvironments contemporaneous with human occupation allowing direct comparisons between sites the la celle tufa northern france provides the longest malacological succession which allows a detailed reconstruction of the development of forest cover successive arrivals of forest species first from an atlantic corridor and later from central and southern european routeways allow characterization of vegetational development the initial immigrants indicate the spread of closed habitats while a peak in the diversity of thermophilous snails corresponds to the optimum phase of deciduous forest expansion a subsequent decrease in forest molluscs together with expansion of hygrophilous species indicates the decline of closed canopy conditions the occurrence of critical forest species especially those now extinct or occurring far beyond their modern ranges provides a framework within which associated acheulean industries can be set

differing controls over the cenozoic pb and nd isotope evolution of deepwater in the central north pacific ocean dissolved pb and nd isotope ratios of seawater as recorded by chemical marine precipitates such as hydrogenetic ferromanganese crusts have been used as paleoenvironmental proxy tracers for the north pacific however all ferromanganese crusts studied so far have either been subject to phosphatization or hydrothermal influence in their old part or only the young parts have been analyzed thus the pb and nd isotope compositions of north pacific deep waters prior to 20 ma are not well constrained we present new results for three ferromanganese crusts one of which cj01 shows no phosphatization and is located far away from the epr its age is inferred to be 75 ma and thus provides for the first time an opportunity to trace the nd and pb isotope evolution of central north pacific seawater back to the latest cretaceous the three crusts no matter whether phosphatized or not display very similar pb and nd isotope trends with age suggesting no modification of the pb and nd isotope distribution by post depositional phosphatization our data suggest that dissolved pb in deep waters of the central north pacific over the cenozoic and latest cretaceous has mainly been derived from eolian dust and only to a minor extent from weathering of island arcs for pb these trends broadly resemble the pb isotope evolution of the eolian silicate dust fraction of core ll44 gpc3 in the central north pacific we suggest that the isotope evolution of dissolved pb in central north pacific seawater has been mainly controlled by pb released from eolian dust from north america prior to 50 ma and after 40 ma from asia in contrast the nd isotope time series of the crusts are by no means similar to the nd isotope evolution of the silicate dust fraction in core gpc3 suggesting a decoupling from the pb and negligible contributions from dust to the dissolved nd in the central north pacific deep water the rise of nd isotope ratios of pacific seawater during the cenozoic has most likely been caused by the increasing volcanic activity and erosion of the volcanic arcs around the pacific

the hafnium and neodymium isotope composition of seawater in the atlantic sector of the southern ocean we present the first combined dissolved hafnium hf and neodymium nd concentrations and isotope compositions of deep water masses from the atlantic sector of the southern ocean eight full depth profiles were analyzed for hf and twelve for nd hafnium concentrations are generally depleted in the upper few hundred meters ranging between 0 2 pmol kg and 0 4 pmol kg and increase to relatively constant values of around 0 6 pmol kg in the deeper water column at the stations north of the polar front pf nd concentrations increase linearly from about 10 pmol kg at depths of 200 m to up to 31 pmol kg close to the bottom indicating particle scavenging and release within the weddell gyre wg however nd concentrations are essentially constant at 25 pmol kg at depths greater than 1000 m the distributions of both elements show a positive correlation with dissolved silicon implying a close linkage to diatom biogeochemistry hafnium essentially shows invariant isotope compositions with values averaging at ehf 4 6 whereas nd isotopes mark distinct differences between water masses such as modified north atlantic deep water nadw end 11 to 10 and antarctic bottom water aabw end 8 6 to 9 6 but also waters locally advected via the agulhas current can be identified by their unradiogenic nd isotope compositions mixing calculations suggest that a small fraction of nd is removed by particle scavenging during mixing of water masses north of the pf nevertheless the nd isotope composition has apparently not been significantly affected by uptake and release of nd from particles as indicated by mixing calculations a mixing envelope of an approximated north pacific and a north atlantic end member shows that nd isotope and concentration patterns in the lower circumpolar deep water lcdw can be fully explained by 30 70 percentage contributions of these respective end members

ostracod distribution and habitat relationships in the kunlun mountains northern tibetan plateau abstract surface sediment samples were collected from the lakes heihai kusai haiding nuur and yan hu and from streams and ponds in the kunlun mountains at the northern margin of the tibetan plateau to investigate the sub fossil ostracod micro crustacean fauna of the region among 65 collected samples 46 ostracod shell rich samples were used to study the relationship between the ostracod distribution and specific conductivity sc of the water which ranged from 0 6 to 53 0 ms cm 1 a total of eleven ostracod species was identified from this region with about half of the species restricted to the tibetan plateau and its adjacent mountain areas and the other half representing holarctic taxa tonnacypris cf estonica and tonnacypris tonnensis are reported from the tibetan plateau for the first time leucocythere sp is the dominant species and ilyocypris cf bradyi is also relatively abundant the other seven species were recorded with limited abundances apparently due to lower sc tolerances leucocythere sp was recorded over the full sc range from 0 6 to 53 ms cm 1 eucypris mareotica is a typical brackish and saline water species which was found at sample sites with high sc 2 8 53 0 ms cm 1 in contrast leucocythere dorsotuberosa candona candida and eucypris afghanistanensis prefer freshwater to slightly oligohaline waters with sc 1 the sc optimum and tolerance range for each species were determined and compared to earlier reported data from other regions of central asia the results indicate that species assemblage data from fossil ostracod shells have a large potential to provide information on past sc levels and more general climate determined moisture conditions

how heat alters underlying deposits and implications for archaeological fire features a controlled experiment abstract while it is true that the use of fire is undoubtedly an important behavioral trait fire can also leave important traces in archaeological deposits including altering previously deposited sediments and artifacts the set of controlled experiments reported here do not focus on fire per se but rather on the effects of some of the most important variables underlying the transfer of heat to subsurface sediments these variables including temperature duration sediment type moisture and mineralogy are altered here in ways that essentially bracket the range of conditions under which past fires may have existed the results show that sediments as much as 10 cm directly below a heat source routinely reach temperatures of 200 c with higher temperatures and greater depth of heat transfer possible with longer durations or higher surface temperatures one of the implications of these results is that a surface can produce substantial thermal alterations of archaeological artifacts and sediments deposited much earlier in the sequence likewise there are significant implications for the analyses and chronometric dating of thermally altered sediments and burned artifacts

marine isotope stage 11 palaeoclimates palaeoenvironments and its role as an analogue for the current interglacial abstract interglacials of the quaternary period are currently the focus of a great deal of attention within the scientific community this is primarily because they play a vital role in distinguishing between natural and human climate change in the current interglacial and in understanding how the holocene would evolve in the absence of anthropogenic greenhouse warming in this respect marine isotope stage 11 mis 11 ca 410 000 yr bp is one of the key interglacial stages of the past 450 000 yr the pattern of insolation variability that occurs during mis 11 matches that which occurs in the holocene more closely than in any other warm stage of the past half a million years in addition there is now an extensive range of evidence for mis 11 palaeoclimates and palaeoenvironments from marine ice core lacustrine and terrestrial sequences the aim of this paper is to provide a comprehensive review of the current state of our understanding of mis 11 this is the first paper to provide a detailed review of mis 11 that incorporates the wide range of marine ice core long lacustrine and terrestrial records that have been generated over the last ten years since the last major overview crucially it is the first review of mis 11 that incorporates a detailed synthesis of the high resolution terrestrial sequences of western and central europe this paper therefore provides a holistic integration of a diverse range of proxies and archives to provide a detailed understanding of the expression of mis 11 in the earth system in particular the review focuses on 1 the climatic background of mis 11 2 the robustness of the identification of mis 11 in a diverse range of sequences 3 the climatic structure of mis 11 4 the magnitude of warmth that occurred in this warm stage 5 mis 11 sea level magnitude and variability 6 the duration of mis 11 7 evidence for abrupt climatic events within the interglacial of mis 11 and 8 precipitation patterns and trends during this interglacial the paper concludes by considering how useful mis 11 is as an analogue for holocene climates and compares it with other proposed analogues such as mis 19 with particular reference to the early anthropogenic hypothesis

the isotopic composition of neodymium in the north pacific abstract we have determined the isotopic composition of neodymium in two water column profiles in the western north pacific and in bottom waters from three other locations in the north pacific the vertical profiles reveal that the water column is stratified with respect to isotopic composition mid depths associated with pacific deep water are uniform having nd 0 3 shallow waters are variable but deep waters are less radiogenic having md 0 4 4 to 5 in the western basin the more negative bottom waters in the western north pacific provide evidence for the advective transport of rare earth elements from antarctic sources to this region bottom waters in the eastern north pacific are more radiogenic nd 0 3 3 to 3 8 indicating very little transport of ree from antarctic sources to this basin overall the isotopic composition of nd in pacific bottom waters appears to be conservative when compared to the silica distribution in spite of evidence for nd removal the findings are generally compatible with other parameters such as temperature salinity and nutrient distributions the presence of nd isotopic signatures associated with antarctic sources in these waters provides evidence for a small component of rare earth elements of north atlantic origin in the bottom waters of the north pacific this is the first tracer evidence to corroborate the suggestion of reid and lynn 1971 that some of the temperature and salinity properties of the deep waters of the north pacific originated in the norwegian and greenland seas

two stage mid brunhes climate transition and mid pleistocene human diversification abstract global climate shifted to markedly warmer interglacial conditions across the mid brunhes transition mbt 400 ka however a global mbt synthesis that spans marine and terrestrial evidence remains elusive which limits our understanding of the role of the mbt in mid pleistocene human evolution we synthesize asian precipitation reconstructions within a context of global palaeoclimatic records and find that the mbt occurred in two stages first stronger warming of northern hemisphere continents weaker southern hemisphere warming and related more extensive northward displacement of the intertropical convergence zone itcz during interglacial marine isotope stage mis 13 intensified and expanded precipitation in asian monsoon regions and in other widespread northern hemisphere regions with accompanying carbon reservoir changes featuring globally high marine benthic 13c values because of vegetation expansion at 500 ka subdued southern hemisphere warming and northward itcz displacement decreased southern hemisphere precipitation simultaneously during mis 13 second a shift to globally warmer interglacials at 400 ka with elevated atmospheric co2 concentrations smaller ice volume and higher sea level resulted in sustained high interglacial precipitation in east asia from mis 11 onward and sustained high marine benthic 13c values during mis 11 we also synthesize palaeoanthropological data and find that the climate and ecosystem changes across the mbt coincided with the timing of human lineage diversification including the emergence of neanderthals and denisovans in eurasia and homo sapiens in africa and their potential coexistence with h heidelbergensis h erectus h floresiensis h naledi and other homo archaics the timing of the mbt also coincided with novel hominin behavioural developments including fire control and the transition from handaxe industries to more versatile levallois techniques combined with environmental theories of human evolution this chronological coincidence suggests a potential link between mid pleistocene environmental changes and human evolution

nd and pb isotopes in atlantic and pacific water masses before and after closure of the panama gateway two nd and pb isotope time series of hydrogenous ferromanganese crusts one from the tehuantepec ridge in the deep eastern equatorial pacific and the other from blake plateau in the shallow northwestern atlantic which cover the past 7 8 m y show no variations coincident with the final closure of the panama gateway estimated as ca 3 5 ma the record of the atlantic crust located in the present day gulf stream shows a shift in isotope composition from ca 8 to 5 ma that is explained by a diminishing supply of pacific water it is argued that the major restriction of water mass exchange through the panama gateway occurred before 5 ma and thus cannot serve as a direct cause of the onset of northern hemisphere glaciation the absence of a significant signature in the isotope records from the pacific crust suggests that the volume of water exchanged with the atlantic through shallow archipelagic straits of the gateway during the 3 4 m y prior to closure was too small to influence the radiogenic isotope composition of pacific deep water

the british lower palaeolithic of the early middle pleistocene the archaeology of britain during the early middle pleistocene mis 19 12 is represented by a number of key sites across eastern and southern england these sites include pakefield happisburgh 1 high lodge warren hill waverley wood boxgrove kent s cavern and westbury sub mendip alongside a background scatter lithic record associated with the principal river systems bytham pre diversion thames and solent and raised beaches westbourne arundel hominin behaviour can be characterised in terms of preferences for temperate or cool temperate climates and open woodland mosaic habitats indicated by mammalian fauna mollusca insects and sediments a biface dominated material culture characterised by technological diversity although with accompanying evidence for distinctive core and flake pakefield and flake tool high lodge assemblages probable direct hunting based subsistence strategies with a focus upon large mammal fauna and generally locally focused spatial and landscape behaviours principally indicated by raw material sources data although with some evidence of dynamic mobile and structured technological systems the british data continues to support a modified short chronology to the north of the alps and the pyrenees with highly sporadic evidence for a hominin presence prior to 500 600 ka although the ages of key assemblages are subject to ongoing debates regarding the chronology of the bytham river terraces and the early middle pleistocene glaciations of east anglia

closing of the central american seaway and the ice age a critical review 1 what role did the closing of the central american seaway play in enabling continental ice sheets to wax and wane over north america and fennoscandia a summary of relevant evidence presented here permits a causal relationship between them but can be interpreted to show none the common denominator of such evidence is the approximate simultaneity of that closing with global cooling and the first major ice advance at the resolution of paleoclimate however geologic evidence from central america places only weak constraints on when interchange between pacific and caribbean water ceased the strongest evidence for when north and south america became connected by a continuous land bridge the great american exchange of vertebrates assigns climate change the causal role for an arid central american climate typical of glacial times seems necessary for animals that inhabited savannas to pass through panama paleoceanographic and geochemical studies of environments and water masses in the eastern pacific western caribbean and atlantic in general call for continual change since 6 ma or earlier if evidence concurrent with global change near 3 5 3 ma seems more widespread than for other times hypothesized connections between a closed seaway and glaciation commonly call for profoundly different north atlantic ocean circulation but simulations using general circulation models provide a spectrum of differences in circulation for open and closed seaways might much not all of the evidence implicating the closing of the seaway in global climate change in fact be a consequence of that change and blind to central america s tectonic development

hydrothermal sediments as a potential record of seawater nd isotope compositions the rainbow vent site 36 14 n mid atlantic ridge 1 geochemical compositions and sr and nd isotopes were measured in two cores collected 2 and 5 km from the rainbow hydrothermal vent site on the mid atlantic ridge overall the cores record enrichments in fe and other metals from hydrothermal fallout but sequential dissolution of the sediments allows discrimination between a leach phase easily leachable and a residue phase refractory the oxy anion and transition metal distribution combined with rare earth element ree patterns suggest that 1 the leach fraction is a mixture of biogenic carbonate and hydrothermal fe mn oxy hydroxide with no significant contribution from detrital material and 2 99 5 of the ree content of the leach fraction is of seawater origin in addition the leach fraction has an average 87sr 86sr ratio indistinguishable from modern seawater at 0 70916 although we lack the nd value of present day deep water at the rainbow vent site we believe that the ree budget of the leach fraction is predominantly of seawater origin we suggest therefore that the leach fraction provides a record of local seawater nd values nd isotope data from these cores span the period of 4 14 ka 14c ages and yield nd values for north east atlantic deep water neadw that are higher 9 3 to 11 1 than those observed in the nearby madeira abyssal plain from the same depth 12 4 0 9 this observation suggests that either the iceland scotland overflow water isow and lower deep water contributions to the formation of neadw are higher along the mid atlantic ridge than in the surrounding basins or that the relative proportion of isow was higher during this period than is observed today this study indicates that hydrothermal sediments have the potential to provide a higher resolution record of deep water nd values and hence deepwater circulation patterns in the oceans than is possible from other types of sediments

longshot experiments to study velocity anisotropy in the oceanic lithosphere of the northwestern pacific abstract several long range explosion seismology experiments have been conducted in the northwestern pacific basin where one of the oldest oceanic lithospheres is postulated to exist the experiments were conducted from 1974 to 1980 highly sensitive ocean bottom seismographs which had been developed for longshot experiments were used the lengths of the profiles ranged from 1000 to 1800 km and the directions were chosen to provide wide azimuthal coverage one of the aims of this series of experiments was to test the existence of velocity anisotropy on a large regional scale the results show that the oceanic lithosphere has anisotropy wherein the velocity changes by 4 7 the anisotropy extends from a depth of at least 40 to 140 km beneath the sea bottom however the magnitude of the anisotropy may vary with depth the azimuth of the maximum velocity is 150 160 clockwise from north and coincides with the fossil direction of spreading of the pacific plate whereas it differs from the present direction of plate motion by 30 the azimuth does not seem to depend on depth in the direction of maximum velocity the lithosphere is basically two layered 8 0 8 2 and 8 6 km s 1 the depth of the interface is 50 60 km beneath the sea floor

trends in caribbean paleoproductivity related to the neogene closure of the central american seaway abstract this study tests the hypothesis that the late miocene to early pliocene constriction and closure of the central american seaway cas connecting the tropical atlantic and east quatorial pacific eep caused a decrease in productivity in the caribbean due to decreased coastal upwelling and an end to the connection with high productivity tropical pacific waters the present study compared paleoceanographic proxies for the interval between 8 3 and 2 5 ma in 47 samples from south caribbean odp site 999 with published data on eep dsdp site 503 proxies for site 999 include the relative abundance of benthic foraminiferal species representing bottom current velocity and the flux of organic matter to the sea floor the ratio of infaunal epifaunal benthic foraminiferal species and benthic foraminifer accumulation rates bfars in addition we calculated resistant planktic foraminifers species and used the previously published sand fraction and benthic carbon isotope values from site 999 during early shoaling of the isthmus 8 3 7 9 ma the caribbean was under mesotrophic conditions with little ventilation of bottom waters and low current velocity the pre closure interval 7 6 4 2 ma saw enhanced seasonal input of phytodetritus with even more reduced ventilation and enhanced dissolution between 6 8 and 4 8 ma during the post closure interval 4 2 2 5 ma in the caribbean paleoproductivity decreased current velocity was reduced and ventilation improved while the seasonality of phytodetrital input was reduced dramatically coinciding with the establishment of the atlantic pacific salinity contrast at 4 2 ma our data support the hypothesis that late miocene constriction of the cas at 7 9 ma and its closure at 4 2 ma caused a gradual decrease in paleoproductivity in the caribbean consistent with decreased current velocity and seasonality of the phytodetrital input

the human occupation of britain during the hoxnian interglacial abstract this paper provides an overview of the mis 11 record for britain the glacial history of britain in particular the anglian glaciation of mis 12 enables the identification of a number of sites that can be attributed to mis 11 the good biological preservation at several of the sites allows correlation between them and therefore a better understanding of the chronology of the associated lithic industries these assemblages can also in some cases be linked to the changing geographic position of britain as sometimes a peninsula and other times an island of mainland europe it means that populations were colonising retreating or becoming locally extinct then recolonizing as the geographic status changed the initial colonisers seem to have lacked handaxe technology although this has been traditionally framed within a parochial clactonian debate this paper suggests that it is better viewed within a european context to understand better the dynamics of population movement and the possible source areas for those populations equally differences in other lithic technologies such as handaxes can be viewed in this light finally the paper suggests that within a european context non handaxes assemblages should be viewed as part of the technocomplex of the acheulian and that there are many other technological and behavioural features that unite the various sites of mis 11 europe

a short circuit in thermohaline circulation a cause for northern hemisphere glaciation the cause of northern hemisphere glaciation about 3 million years ago remains uncertain closing the panamanian isthmus increased thermohaline circulation and enhanced moisture supply to high latitudes but the accompanying heat would have inhibited ice growth one possible solution is that enhanced moisture transported to eurasia also enhanced freshwater delivery to the arctic via siberian rivers freshwater input to the arctic would facilitate sea ice formation increase the albedo and isolate the high heat capacity of the ocean from the atmosphere it would also act as a negative feedback on the efficiency of the conveyor belt heat pump

holywell coombe folkestone a 13 000 year history of an english chalkland valley abstract holywell coombe is a valley cut into the scarp face of the north downs chalk cuesta near folkestone kent its geological importance stems from a highly fossiliferous sequence of lateglacial and holocene deposits that line the valley floor these have yielded a molluscan succession of particular importance providing a record of environmental change throughout the past 13 000 radiocarbon years waterlogging of the basal deposits has prevented oxidation leading to the preservation of a range of organic fossils such as plant and insect remains that normally do not survive in calcareous environments this enables linkage between faunal and vegetational records allowing the differential rates of response of particular groups to be critically compared the importance of the site was revealed in 1968 in trial pits connected with an aborted channel tunnel project resurrection of plans to build a tunnel led in 1987 to major rescue excavations and multidisciplinary investigations the results of which are reviewed here a three dimensional picture of the valley infill was established from a network of 180 boreholes critical parts of the sequence were investigated in specially excavated trenches and sections exposed during construction of the tunnel systematic sampling at a number of locations within the valley provided a palaeontological record from the full stratigraphical succession a number of lateglacial and holocene soils were found to be represented in the sequence including that formed during the allerod phase of the lateglacial interstadial the molluscan zonation scheme previously defined at holywell coombe and applicable over large areas of southern britain and possibly further afield has been refined and dated with greater precision the lateglacial sequence has been extended back to the early part of the lateglacial interstadial by this study and the site chronology is now underpinned by over 35 new radiocarbon dates quantitative palaeoclimatic reconstructions from beetle remains using the mutual climatic range method cover the period between 13 000 and 9000 yr bp the earliest sediments marsh deposits with thermophilous insect taxa and a species poor molluscan assemblage date from around 13 000 12 000 yr bp just before the end of this period changes in beetle faunas record climatic cooling heralding slope instability and the accumulation of thick colluvial deposits by 11 500 yr bp the climate had stabilized and slope movement had ceased allowing the formation of the allerod soil there followed a major deterioration to the arctic climate of the younger dryas during which renewed erosion from the valley sides brought further material onto its floor burying and sealing the earlier sediments the beginning of the holocene saw the onset of tufa formation around two dominant springs in the upper valley there was progressive development of forest hazel dominated woodland being established by 9500 yr bp there is some evidence for thinning of the forest canopy during the late mesolithic and neolithic but the major clearance occurred during the early bronze age causing renewed instability on slopes and consequent hillwash accumulation this final depositional phase continued with pauses marked by soil formation in the early bronze age and the iron age to the present day the hillwash seals structures relating to prehistoric human activity including plough marks and contains an extensive sequence of artefacts

closure of the central american isthmus and its effect on deep water formation in the north atlantic modern ocean thermohaline driven circulation influences global climate by transporting heat to high latitudes1 2 and by affecting the exchange of co2 between ocean and atmosphere3 north atlantic deep water nadw plays a key role in this circulation and quaternary climate cycles have been linked to changes in nadw flow4 general circulation model simulations indicate that before closure some 3 4 million years ago of the central american isthmus the narrow strip of land linking north and south america the direct flow of low salinity water from the pacific to the atlantic ocean would have led to a smaller nadw flow5 6 sedimentation patterns7 and nutrient proxies8 11 support these model results by indicating an increase in nadw flow around the time of isthmus closure but these records do not allow changes in different nadw sources to be distinguished and the overall effect of closure on global ocean circulation is poorly known here we present nd pb and sr isotope records preserved by a hydrogenous ferromanganese crust from the nadw flow path in the western north atlantic ocean these records indicate that the isotopic signal associated with nadw strengthened around 3 4 million years ago showing that deep water that formed in the labrador sea made a gradually increasing contribution to nadw flow these data taken together with those from the central pacific ocean12 indicate an increased nadw flow since isthmus closure and suggest that the closure established today s general pattern of ocean circulation

oldest evidence of acheulean occupation in the upper seine valley france from an mis 11 tufa at la celle the tufa deposit of la celle located in the upper seine valley northern france has been known for more than a century and extensive collections of shells and leaf impressions exist these fossils led earlier authors to recognize the tufa as evidence of an old temperate phase of the pleistocene new studies have recently been undertaken at the site in order to reappraise its palaeontological potential and to improve its dating recent investigations are based on the analysis of a new series of stratified samples coupled with a revision of material in several old collections the new work shows that the tufa accumulated under interglacial conditions and demonstrates the progressive development of forest biotopes culminating in the climatic optimum in the upper levels the reopening of the landscape is registered by both molluscan communities and plant remains the tufa at la celle has been correlated with mis 11 based on the geomorphological context of the site together with the occurrence of the lyrodiscus fauna a malacological assemblage characteristic of tufa deposits of this period in northwest europe this correlation is supported by radiometric measurements u series and esr u series which have produced a mean age of w400 ka mammalian remains are also preserved and include macaca and hippopotamus which are the first well provenanced records of these species from this region an archaeological horizon with flint artefacts demonstrates human occupation during the interglacial optimum analysis of the lithic artefacts confirms their similarity with the acheulean assemblage collected at the end of the 19th century la celle therefore represents one of the best dated acheulean occupation sites in northern france and one where the palaeoenvironmental context can be described in great detail

evidence for the repeated use of a central hearth at middle pleistocene 300 ky ago qesem cave israel abstract a major debate in prehistory revolves around the time and place of the earliest habitual use of fire and the hominin species responsible for it here we present a newly discovered hearth at qesem cave israel that was repeatedly used and was the focus of hearth centered human activities as early as three hundred thousand years ago the hearth identified based on mineralogical and microscopic criteria contains two superimposed use cycles each composed of shorter episodes possibly the earliest superimposed hearth securely identified to date the hearth covers ca 4 m 2 in area making it a uniquely large hearth in comparison to any contemporaneous hearth identified thus far possibly indicating it has been used by a relatively large group of people in addition the hearth is located in the center of the cave and is associated with butchered animal remains and a dense flint assemblage the flint assemblage indicates spatially differentiated meat cutting and hide working activity areas the central location of the hearth within the cave and the activities associated with it may reflect an embedded perception of space organization of the qesem cave inhabitants since fire was habitually used throughout the 420 200 ky sequence of qesem cave where preservation conditions are alike throughout we suggest that this unique hearth may reflect a development in nature and most probably in the intensity of fire use in qesem cave from ca 300 ka ago onwards

actual timing of neodymium isotopic variations recorded by femn crusts in the western north atlantic hydrogenetic ferromanganese femn crusts from the western north atlantic record variations in the nd and pb isotopic composition of cenozoic deep water preserved during their growth the timing and cause of the most striking change have been the subject of debate some have proposed that the shift took place after 4 ma in response to the closure of the panama gateway others have argued that the major change in isotope composition occurred as early as 8 ma this study presents high resolution nd isotope records for crusts previously dated using 10be 9be chronology these data confirm that the shifts in nd occurred after 4 ma consistent with a likely relationship with the closure of the central american isthmus and intensification of northern hemisphere glaciation and in accordance with changes seen in other physical and chemical records these results illustrate the need for both a robust chronological framework and high resolution records before a reliable paleoceanographic interpretation can be made of the variations recorded by femn crusts

neogene stratigraphy paleoceanography and paleobiogeography in northwest south america and the evolution of the panama seaway abstract the atrato basin in the pacific coastal region of nw south america colombia exhibits stratigraphic and biostratigraphic characteristics similar to other neogene pacific coastal basins of southern central america and northern south america an evaluation of the neogene stratigraphy and foraminiferal biostratigraphy with emphasis on paleoceanographic and paleobiogeographic phenomena indicate the following 1 previous to the middle miocene well aerated deep and open oceanic conditions and free and active water circulation prevailed along the steep continental margins of nw south america 2 during the early middle miocene right after the neogene hiatus nh 2 15 2 ma tectonic disturbances triggered the initial uplift of the panama sill bottom water circulation foraminiferal and sedimentation changes are observed in both the pacific and caribbean coastal areas of nw south america 3 during the middle miocene coinciding with the neogene hiatus nh 3 12 9 11 8 ma an abrupt paleobathymetric change from lower to middle bathyal depths indicates a major uplift of the panama sill to about 1000 m reflecting the middle miocene tectonic disturbances in nw south america 4 during the late middle miocene immediately following this uplift a distinctive pacific benthic foraminiferal fauna abruptly appeared and extended from ecuador to california because these assemblages do not occur in the adjacent caribbean region a circulation barrier between the atlantic and pacific oceans as a result of intensification of the cool marginal california current is proposed anoxic middle to upper bathyal environments prevailed under well aerated cool surface waters in the pacific coastal areas of nw south america 5 during the latest miocene immediately following the neogene hiatus nh 6 7 0 6 3 ma surface water circulation between the caribbean and the pacific was re established and the previous influence of the california current disappeared a rapid filling and shallowing of the basin to mostly neritic depths is indicated along the pacific and caribbean coastal basins of colombia as well as a progressive increase in similarity between the coastal pacific and caribbean benthic biotas this shallowing in the early late miocene also appears to have been associated with the earliest terrestrial interchange of ground sloths to north america and raccoons and their allies to south america 6 immediately following early pliocene time the panamanian isthmus became completely emergent providing a terrestrial environment favourable for intermingling of terrestrial faunas and floras between north and south america i correlate this pliocene uplift with the neogene hiatus nh 8 3 7 3 1 ma four regional unconformities associated with tectonic disturbances in the nw corner of south america have also been recognized and correlated with neogene hiatuses recorded from the oceans early middle miocene middle miocene late miocene and early pliocene

major river systems of central and southern britain during the early and middle pleistocene central and southern britain was drained by two main river systems during the larger part of the early and middle pleistocene the thames and bytham rivers evidence for these rivers and their quaternary history is represented by their sediments the kesgrave and bytham sands and gravels respectively the geomorphological position of the sediments biostratigraphy and amino acid geochronology evidence from the earlier parts of the early pleistocene tiglian c4b and earlier indicates low energy river systems and marine conditions over much of east anglia for most of the early pleistocene tiglian c4c to the cromerian complex the ancestral thames was the main river with at its maximal extent a catchment that extended into wales and across east anglia and what is now the north sea to join the ancestral rhine during this period glaciers in the uplands of wales and periglacial mass movement elsewhere supplied material to the catchment and it was at this time that the bulk of the sorted quaternary ssediments of lowland britain were deposited the bytham river system has no successor because the landscape now in existence has been fundamentally altered by glacial erosion this catchment drained most of midland england and joined the thames in central east anglia initially the bytham river was a tributary of the thames but over time it extended its catchment and at the beginning of the cromerian complex it became the main river of southern britain with the anglian glaciation 01 stage 121 the bytham river was destroyed and the thames was diverted to its present route through london

humans in the hoxnian habitat context and fire use at beeches pit west stow suffolk uk a lower palaeolithic industry at beeches pit west stow suffolk occurs within an interglacial sequence that immediately overlies glacial deposits referable to the anglian lowestoft formation there is strong biostratigraphical evidence from both vertebrates and molluscs that the interglacial represented is the hoxnian mis 11 this conclusion is supported by uranium series dates from carbonate nodules 400 kyr tl dates from burnt flint 414 30 kyr and a range of amino acid racemisation data the archaeology consists of flint artefacts of acheulian character including many refitting examples charred material is abundant in three stratigraphical units and many bones and flints have been burnt indicating repeated occurrence of fire several discrete areas of burnt sediment appear to be hearths this interpretation is supported by 1 the intensity of burning 600 8008c implied by the charred and calcined bones 2 the intersection of two of the burnt areas implying separate burning events at slightly different overlapping locations 3 the discovery of two burnt flakes that refit onto an adjacent group that are unburnt indicating that the burning was highly localised and 4 the spatial distribution of artefacts respects the features interpreted as hearths suggesting fireside knapping fossils associated with the archaeology indicate occupation within closed deciduous forest in a fully temperate climate attractions to this unusual environment would have included the fresh water provided by springs a rich supply of potential food and a prolific source of good quality flint for tool manufacture the archaeological evidence therefore suggests that the site repeatedly served as an area of focused activities perhaps a home base during much of the interglacial the upper levels of the sequence provide clear faunal evidence of climatic deterioration during which human occupation and fire use persisted biostratigraphical correlations with other lower palaeolithic sites lend support to the suggestion that acheulian and clactonian industries occurred in britain during the same substage of the hoxnian although not necessarily at precisely the same time copyright 2006 john wiley sons ltd

west european terrestrial molluscs assemblages of isotopic stage 11 middle pleistocene climatic implications rousseau d d puiss6gur j j and lecolle f 1992 west european terrestrial molluscs assemblages of isotopic stage ii middle pleistocene climatic implications palaeogeogr palaeoclimatol palaeoecol 92 15 29 tufil deposits in the seine and the avelasse valleys have yielded numerous molluscs assemblages belonging to the lyrodiscus biome these malacofaunas primilarily indicative of forest which developed under a warm climate have no present day counterpart the biostratigraphical study of several localities based on new investigations at vernon seine valley and arrest avelasse valley and a reexamination of the faunas from st pierre les eibeuf suggests the allocation of a holsleinian age this is supported by u th dates for vernon and the stratigraphy of the loess sequence of st pierre les elbeuf similar assemblages yielded by tufas of the same age in england and germany indicate that the lyrodiscus biome was widespread the warm climate recorded by the molluscs of the tufa deposits is in agreement with pollen and marine analyses for the isotopic stage 11 362 423 kyr b p in this way the lyrodiscus biome appears as an interesting marker for the continental quaternary in western europe if the occurrence of these particular molluscan assemblages is due to climate refuges from the declined tertiary biota from which i e r lyrodiscu s could have emigrated also needed to exist

plate tectonics radiogenic isotopic tracers and paleoceanography the case of the manganese crusts in the pacific abstract hydrogenous ferromanganese crust deposits on seafloor and volcanic seamounts are archives of past isotopic compositions of the ocean isotopic compositions of long life radiogenic isotopes that are dissolved in the ocean such as nd and pb are mixtures of different erosion products continents volcanics arcs ridges etc transported by oceanic currents or winds isotopic studies on mn crusts are thus potential paleogeographic and paleoceanographic tracers however global paleogeography can drastically evolve over the period of growth of crust as well as the latitude longitude and water depth of the mn crust thus each crust sampled a succession of geographic sites related to its spatial evolution through time for this reason valid information about the past ocean isotopic composition can only be extracted from mn crust under the condition that the successive paleogeographic and paleodepth positions can be reconstructed for each mn crust we followed this approach for six hydrogenous mn crusts from the pacific ocean that have recorded pb and nd isotopic signals for the past 80 myr the evolution of the isotopic data was considered within a proper geodynamical framework that takes into account the paleopositions of the pacific plate and surrounding continents of the hot spots and ridges as well as the paths of the six crusts the differences and similarities between the pb and nd revealed by our analysis emphasize their complementarity as paleoceanographic tracers the nd isotopes are strongly influenced by the exchange between indian and pacific waters specifically by the progressive closure of the indonesian gateway the closed central pacific characteristics are defined from the extrapolation of the isotopic trend this highlights the important role played by erosion of volcanic arcs in the nd isotopic value of seawater our approach also stresses the influence of local volcanic activity ridges or active hot spot for lead isotopes

pre anglian fluvial and coastal deposits in eastern england lithostratigraphy and palaeoenvironments abstract clast lithology and derived microflora are used to provide a basis for correlating pre anglian fluvial and coastal deposits in eastern england and to provide a lithostratigraphic framework for these early and early middle pleistocene sediments three fluvial systems are recognised i the thames which drained an area from wales through midland england to the thames basin and southern east anglia the catchment was truncated over the period concerned and the western headwaters diverted to other river systems ii the bytham river which drained midland england and the southern pennines and reached the southern north sea delta in the region of north central east anglia this river extended its catchment over the period concerned iii the ancaster river which drained the southern pennines and received sediment from northeast england each of these catchments contributed sediment to the southern north sea delta estuary and contributed to the lithologies of the red norwich and wroxham crag formations the lithostratigraphic subdivisions are based on the fact that i the pliocene and early pleistocene rivers and the equivalent red and norwich crags are characterised by far travelled microflora which was transported in suspension and a locally derived clast assemblage transported as bedload and ii the later early and early middle pleistocene rivers and the equivalent wroxham crag are characterised by a far travelled microflora and a far travelled clast assemblage variations in the amount and composition of far travelled materials is determined by the relative importance of the three river systems this provides a basis for identifying different formations of the thames river sediments older sudbury formation and younger colchester formation and different members of the wroxham formation dobb s plantation member local material with minor components of thames and ancaster river sediments how hill member local material with major components of thames and ancaster river sediments mundesley member with major components of bytham river sediments these lithostratigraphic units are related to established north european biostratigraphy and oxygen isotope stratigraphy the factors forcing the changes in river energetics are explained in terms of the relative importance of geomorphic processes operating within the river catchments determined by the patterns of milankovitch orbital forcing

the late miocene panama isthmian strait miocene sediments of the caribbean gatun and chagres formations panama canal basin were deposited within an archipelagic strait that connected caribbean and pacific waters shallow water 25 m benthic foraminifera of the gatun formation have a strong caribbean affinity indicating that a significant interoceanic biogeographic barrier had formed at 8 ma however benthic foraminifera of the overlying chagres formation are bathyal and markedly pacific in affinity indicating that at 6 ma waters of the panama isthmian strait deepened to 200 500 m and pacific bathyal waters flowed into the caribbean the chagres formation crops out at the caribbean entrance to the panama canal in a large wedge of cross laminated sandstone and coquina the cross laminations and coarse grain size indicate high energy currents atypical of bathyal settings we infer that a jet of the pacific north equatorial countercurrent equatorial undercurrent passed through the panama isthmian strait to deposit these sediments on the caribbean side this later entry of pacific taxa into the caribbean had no apparent effect on the subsequent composition of caribbean faunas

excavations at the lower palaeolithic site at east farm barnham suffolk 1989 92 preliminary results are presented from three seasons9 work at the lower palaeolithic site at barnham the complex stratigraphy is described and a provisional interpretation given which suggests that the archaeological deposits date to a warm phase after the anglian middle pleistocene cold stage a fauna1 assemblage from the deposits is described providing an environmental and biostratigraphic context for the site further geochronological control is provided by amino acid ratios on shells from the sequence two flint assemblages have been excavated the first consisting of flakes and cores and the second including bifaces these assemblages and their position in the british sequence are considered in terms of their stratigraphic context and their relationship to other lower palaeolithic assemblages in the british isles

middle pleistocene interglacial thames medway deposits at clacton on sea england reconsideration of the biostratigraphical and environmental context of the type clactonian palaeolithic industry abstract in 1987 an archaeological investigation was undertaken during redevelopment of the erstwhile butlin s holiday camp at clacton on sea on the grounds that the middle pleistocene clacton channel deposits containing the type clactonian palaeolithic industry were known to extend beneath the site excavations for a storm drain allowed sampling at points along a longitudinal traverse of the main clacton channel analysis of these samples has provided new palaeontological information including data pertaining to the rise in relative sea level during the interglacial represented systematic studies of molluscs and ostracods the latter undertaken at clacton for the first time have been particularly valuable information from the butlin s site supplements evidence previously gathered from the west cliff section and from other localities at clacton the calcareous clay marl that underlies the clacton golf course extends beneath butlin s where it was found to be part of the freshwater beds not the estuarine beds as hitherto supposed the clacton estuarine beds restricted to the eastern end of the site have their base just below 2 m o d implying that their superposition upon the clacton freshwater beds occurred when relative sea level in this area was close to present ordnance datum correlation of the clacton channel deposits with the interglacial immediately following the anglian elsterian stage appears secure equivalence with oxygen isotope stage 11 of the oceanic sequence is most probable a borehole survey and subsequent excavation revealed a holocene sequence of unlithified tufa and organic sediments beneath part of the site

the use of foraminifera as a record of the past neodymium isotope composition of seawater 1 we present new isotopic data for sedimentary planktonic foraminifera as well as for potential water column and sedimentary sources of neodymium nd which confirm that the isotopic composition of the foraminifera is the same as surface seawater and very different from deep water and sedimentary nd the faithfulness with which sedimentary foraminifera record the isotopic signature of surface seawater nd is difficult to explain given their variable and high nd ca ratios ratios that are often sedimentary foraminifera ratios that are often much higher than is plausible for direct incorporation within the calcite structure we present further data that demonstrate a similarly large range in nd ca ratios in plankton tow foraminifera a range that may be controlled by redox conditions in the water column cleaning experiments reveal in common with earlier work that large amounts of nd are released by cleaning with both hydrazine and diethylene triamine penta acetic acid but that the nd released at each step is of surface origin while further detailed studies are required to verify the exact location of the surface isotopic signature and the key controls on foraminiferal nd isotope systematics these new data place the use of planktonic foraminifera as recorders of surface water nd isotope ratios and thus of variations in the past supply of nd to the oceans from the continents via weathering and erosion on a reasonably sure footing

progress in faunal correlation of late cenozoic fluvial sequences 2000 4 the report of the igcp 449 biostratigraphy subgroup abstract vertebrate and invertebrate faunal biostratigraphy is a well tested method for establishing relative chronologies for fluviatile sequences that has proved useful in many parts of the world the robust bones and teeth of large mammals are commonly found in fluviatile deposits whereas small vertebrates can be readily recovered through systematic sieving of calcareous sediments as can molluscs the other major faunal group that has been used for biostratigraphical analysis of fluvial sequences because of their rapid and quantifiable rates of evolution extinction body mass change and dispersal during the late cenozoic mammals are especially useful for ordering the fragmentary terrestrial sequence of interglacials and glacials and proposing correlation with the global marine climatostratigraphic record other groups e g reptiles and amphibians ostracods are as yet only in the initial stages of development as a dating tool whereas some e g fish birds still require substantial development in order to fully explore their utility as part of igcp 449 vertebrate and molluscan assemblages have made important contributions to datasets from a number of areas notably northern france central germany the czech republic and the ukraine further south mammalian assemblages have proved useful in separating discrete periods of climatic change in iberia and syria at greater distances from the core area of fluvial biostratigraphical archives significant contributions have come from south america uruguay river south africa vaal and australia riverine plain and lake eyre drainage basin

strontium neodymium and lead isotope variations of authigenic and silicate sediment components from the late cenozoic arctic ocean implications for sediment provenance and the source of trace metals in seawater proven ance changes of silicate sediment deposited during the late cenozoic 5 0 ma on the alpha ridge central arctic ocean are determined from variations in strontium lead and neodymium isotope compositions whereas strontium and lead isotope compositions are relatively invariant from 5 to 1 7 ma end values start to increase at 3 ma subsequently s7sr 86sr and 2 6pb z 4pb ratios progressively increase and end values progressively decrease from 1 7 ma to the present day from these isotope variations three different endmember compositions for sediment source regions are defined the two endmember compositions defined by sediment that was deposited by sea ice from 5 to 1 7 ma are consistent with a significant component being derived from the east siberian shelf the progressive change in isotope compositions from 1 7 to 0 ma correlates with an increase in coarse detritus deposited by icebergs over this time period the isotope data are consistent with a progressive increase in the proportion of sediment that was deposited in the central arctic ocean since 1 7 ma having been derived from the northern canada or queen elizabeth island region changes in the strontium neodymium and lead isotope compositions of arctic seawater are determined by analyzing the oxide fractions of fe mn micronodules strontium isotope compositions of the microno dule oxide fractions are similar to published late cenozoic seawater data and indicate that 97 of the sr is seawater derived but minute contributions of sr from silicate detritus prohibit using the hydrogenous fractions for chronostratigraphic purposes neodymium and lead isotope compositions of the micronodule oxide fractions which reflect those of arctic seawater follow the isotope variations of the silicate components throughout the late cenozoic these relations indicate that river water can not be the primary source of rare earth elements and pb to the dissolved reservoir in arctic seawater and that ice rafted detritus by dissolution or exchange processes is an important source of trace elements to seawater in ice covered oceans copyright 1997 elsevier science ltd

differentiation of the british late middle pleistocene interglacials the evidence from mammalian biostratigraphy abstract acknowledgement of the climatic complexities of the marine oxygen isotope 18o record has inspired fresh investigations into methods of identifying and separating interglacial deposits on land biostratigraphical analysis of fossil mammalian assemblages particularly those from long fluvial sequences has proved to be a uniquely valuable technique in the differentiation of the various temperate episodes of the late middle pleistocene in britain thereby enabling a sequence of diagnostic mammalian assemblage zones to be established the scheme has provided an important means of correlation between geographically distant localities and between different types of depositional environment using mammalian biostratigraphical information this paper explores the evidence for three post anglian interglacials prior to the last ipswichian interglacial correlated with stages 11 9 and 7 of the oxygen isotope record and presents the case for the recognition of much smaller scale environmental and climatic oscillations within these interglacials possibly corresponding to marine isotopic substages

response of beryllium and radiogenic isotope ratios in northern atlantic deep water to the onset of northern hemisphere glaciation we present time corrected ratios of cosmogenic 10 be to continent sourced 9 be from two fe mn crusts located in the northwest atlantic in the vicinity of the origins of northern atlantic deep water nadw these initial 10 be 9 be ratios represent those of the ambient seawater at the time of crust deposition and are constant through the last 7 ma previously published isotope records of radiogenic nd and pb isotopes in these crusts show a decrease in e nd and an increase in 206 pb 204 pb over the last 5 ma these changes are consistent with a gradual increase in the strength of nadw production an increase in the labrador sea component of nadw or an increased erosional input into the labrador sea since the residence time and thus the advective length scales of dissolved be in deep water lie between those of nd and pb records of 10 be 9 be should contrary to what has been observed vary in phase with those of nd and pb if these variations are accounted for by changes in paleo circulation the observed variations in radiogenic nd and pb isotopes are therefore most likely to be explained with an increase in the flux of terrigenous matter in the area of the labrador sea which was possibly associated with ice rafting and selective leaching of pb isotopes an increase of the labrador sea component that contributes to nadw is also a possibility but based on the 10 be 9 be data presented here large scale changes in the thermohaline circulation can be discounted as cause for the radiogenic tracer variations

the role of co2 decline for the onset of northern hemisphere glaciation the pliocene pleistocene transition ppt from around 3 2 to 2 5 million years ago ma represented a major shift in the climate system and was characterized by a gradual cooling trend and the appearance of large continental ice sheets over northern eurasia and north america paleo evidence indicates that the ppt was accompanied and possibly caused by a decrease in atmospheric co2 but the temporal resolution of co2 reconstructions is low for this period of time and uncertainties remain large therefore instead of applying existent co2 reconstructions we solved an inverse problem by finding a schematic co2 concentration scenario that allows us to simulate the temporal evolution of key climate characteristics in agreement with paleoclimate records to this end we performed an ensemble of transient simulations with an earth system model of intermediate complexity from which we derived a best guess transient co2 scenario for the interval from 3 2 to 2 4 ma that gives the best fit between the simulated and reconstructed benthic 18o and global sea surface temperature evolution our data constrained co2 scenarios are consistent with recent co2 reconstructions and suggest a gradual co2 decline from 375 425 to 275 300 ppm between 3 2 and 2 4 ma in addition to a gradual decline the best fit to paleoclimate data requires the existence of pronounced co2 variability coherent with the 41 kyr 1 kyr 1000 years obliquity cycle in our simulations the long term co2 decline is accompanied by a relatively abrupt intensification of northern hemisphere glaciation at around 2 7 ma this is the result of a threshold behaviour of the ice sheets response to gradual co2 decrease and orbital forcing the simulated northern hemisphere ice sheets during the early pleistocene glacial cycles reach a maximum volume equivalent to a sea level drop of about 40 m both ice volume and benthic 18o are dominated by 41 kyr cyclicity our simulations suggest that before 2 7 ma greenland was ice free during summer insolation maxima and only partly ice covered during periods of minimum summer insolation a fully glaciated greenland comparable to its present day ice volume is modelled only during glacial maxima after 2 7 ma and more continuously after 2 5 ma

neogene overflow of northern component water at the greenland scotland ridge in the north atlantic ocean flow of north atlantic deep water nadw and of its ancient counterpart northern component water ncw across the greenland scotland ridge gsr is thought to have played an important role in ocean circulation over the last 60 ma the iceland plume has dynamically supported an area which encompasses the gsr consequently bathymetry of the gsr has varied with time due to a combination of lithospheric plate cooling and fluctuations in the temperature and buoyancy within the underlying convecting mantle here we reassess the importance of plate cooling and convective control on this northern gateway for ncw flow during the neogene period following wright and miller 1996 to tackle the problem benthic foraminiferal isotope data sets have been assembled to examine 13c gradients between the three major deep water masses i e northern component water southern ocean water and pacific ocean water composite records are reported on an astronomical timescale and a nonparametric curve fitting technique is used to produce regional estimates of 13c for each water mass confidence bands were calculated and error propagation techniques used to estimate ncw and its uncertainty despite obvious reservations about using long term variations of 13c from disparate analyses and settings and despite considerable uncertainties in our understanding of ancient oceanic transport pathways the variation of ncw through time is consistent with independent estimates of the temporal variation of dynamical support associated with the iceland plume prior to 12 ma 13c patterns overlap and ncw cannot be isolated significant long period variations are evident which are consistent with previously published work from 12 ma when lithospheric cooling probably caused the gsr to submerge completely long period 13c patterns diverge significantly and allow reasonable ncw estimates to be made our most robust result is a dramatic increase in ncw overflow between 6 and 2 ma when dynamical support generated by the iceland plume was weakest between 6 and 12 ma a series of variations in ncw overflow have been resolved

the initiation of northern hemisphere glaciation for well over a century scientists have speculated that variations in the atmospheric concentration of radiatively important trace gases such as carbon dioxide could control the earth s climate e g arrhenius 1 896 recent observations of significant glacial interglacial variation in atmo spheric co2 in ice cores put this idea on a firm observational as well as theoretical footing e g barnola et ai1 987 in this century as atmospheric co2 levels creep steadily upwards in response to the burning of fossil fuels and forests the specter of manmade global climate change looms before us ipcc 1990 a possibility that has heightened interest in the natural variability of climate in the past in particular the 3 c warming pre dicted for the next century has stimulated interest in past warm climates such as the middle pliocene around 3 0 million years ma ago an interval that has often been invoked as a greenhouse world budyko et al 1985 in this paper the climate transition from the warm mid pliocene around 3 2 ma to the onset of northern hemisphere ice ages around 2 4 ma is examined evidence for the initiation of significant northern hemisphere glaciation is examined as well as how this event affected climate around the globe while the cause of individual glacial interglacial oscillations is tied to milankovitch variations in the earth s orbit around the sun e g imbrie et ai 1 992 these insolation changes cannot account for the long term cooling trend which culminated in northern hemisphere glaciation in the final section of this paper mechanisms of long term climate change

evolution of nd and pb isotopes in central pacific seawater from ferromanganese crusts abstract hydrogenetic ferromanganese crusts incorporate elements from ambient seawater during their growth on seamounts by analysing nd pb and be isotope profiles within crusts it is possible to reconstruct seawater tracer histories depth profiles of 10be 9be ratios in three pacific ferromanganese crusts have been used to obtain growth rates which are between 1 4 and 3 8 mm ma nd and pb isotopes provide intact records of isotopic variations in pacific seawater over the last 20 ma or more there were only small changes in pb isotope composition in the last 20 ma this indicates a constant pb composition for the erosional sources and suggests further that erosional nd inputs may have been uniform too end values vary considerably with time and most probably reflect changes in ocean circulation the end values of the crusts not only vary as a function of age but also as a function of water depth from 25 to 0 ma crust va13 2 from 4 8 km water depth has a similar pattern of end variation to the two shallower crusts from 1 8 and 2 3 km but about 1 0 to 1 5 units more negative this suggests that end stratification in pacific seawater as demonstrated for the present day has been maintained for at least 20 ma each crust shows a decrease in end from 3 5 ma to the present which is interpreted in terms of an increase in the nadw component present in the pacific from 10 to 3 5 ma ago the crusts show an increase in end this suggests a decreasing role for a deep water source with end less than circum pacific sources in this regard the panamanian gateway restriction from 10 ma with final closure at 3 5 ma may have played an important role in reducing access of atlantic derived nd to the pacific

miocene deepwater oceanography a global synthesis of miocene benthic foraminiferal carbon and oxygen isotopic and faunal abundance data indicates that miocene thermohaline circulation evolved through three regimes corresponding approximately to early middle and late miocene times there is evidence for major qualitative differences between the circulation of the modern ocean and the miocene ocean prior to 11 ma the 13c 12c ratios of the benthic foraminifera cibicidoides are interpreted in terms of water mass aging i e the progressive depletion of dissolved o2 and lowering of 13c values as the result of oxidation of organic matter as water flows further from its sources at the surface of the oceans both isotopic and faunal data indicate that the early miocene regime from 22 to 15 ma was the most different from today s during that interval intermediate and deep waters of both the atlantic and the pacific oceans aged in a northward direction and the intermediate waters of the indian the south atlantic and the south pacific oceans were consistently the youngest in the global ocean we speculate that early miocene global thermohaline circulation may have been strongly influenced by the influx of warm saline water tethyan indian saline water from the tethys into the northern indian ocean the isotopic and faunal data suggest that flow from the tethyan region into the indian ocean diminished or terminated at about 14 ma isotopic and faunal data give no evidence for north atlantic deep water nadw formation prior to about 14 5 ma with the exception of a brief episode in the early miocene from 14 5 to 11 ma nadw formation was weak and circumpolar and antarctic water flooded the deep south atlantic and south pacific as the antarctic ice cap grew from about 10 ma to the end of the miocene thermohaline circulation resembled the modern circulation in many ways in latest miocene time 6 to 5 ma circulation patterns were very similar to today s except that nadw formation was greatly diminished the distribution pattern of siliceous oozes in miocene sediments is consistent with our proposed reconstruction of thermohaline circulation major changes which occurred in circulation during the middle miocene were probably related to the closing of the tethys and may have contributed to rapid middle miocene growth of the antarctic ice cap appendices 1 4 6 and 7 are available withentire article on microfiche order fromamerican geophysical union 2000 floridaavenue n w washington dc 20009 document 88p 002 5 00 payment mustaccompany order

isotopic paleoceanography of the caribbean and east pacific role of panama uplift in late neogene time comparisons of carbon isotopic data on benthic foraminifera from deep sea drilling project sites 502 western caribbean and 503 eastern pacific indicate that the difference between the atlantic and the pacific in the per mil enrichment in carbon 13 of total dissolved carbon dioxide increased about 6 million years ago and again 3 million years ago when the difference reached the modern level 1 per mil comparisons of planktonic foraminiferal oxygen isotopic data for the caribbean and the pacific suggest that the salinity of caribbean surface waters began increasing 4 million years ago possibly in response to shoaling of the panama isthmus these results suggest that modern circulation patterns in the caribbean and eastern pacific developed by 3 million years ago in concert with changing tectonic climatic and biogeographic patterns

terrestrial environments during mis 11 evidence from the palaeolithic site at west stow suffolk uk abstract multidisciplinary investigations of the sequence at beeches pit west stow suffolk uk have a direct bearing the age of the hoxnian interglacial and its correlation with the continental holsteinian and with the global marine record at this site glacial deposits till and outwash gravels referable to the anglian lowestoft formation fill a subglacial channel cut in chalk bedrock above these glacial deposits a series of interglacial sediments occurs consisting of limnic tufaceous and colluvial silts lacking pollen but rich in shells ostracods and vertebrates lower palaeolithic flint artefacts of acheulian character have also been recovered including refitting examples charred material is abundant at certain horizons and many of the bones have been burned several discrete areas of burnt sediment are interpreted as hearths the molluscan fauna comprises some 78 taxa and includes species of considerable zoogeographical and biostratigraphical importance the land snail assemblage from the tufa consists of woodland taxa with no modern analogue including species that are either extinct e g zonitoides sepultus or which no longer live in britain e g platyla polita p similis neniatlanta pauli this is also the type locality of retinella lyrodiscus skertchlyi which belongs to a subgenus of zonitid land snail now living only on the canary islands there are indications from this fauna the lyrodiscus biome that the climate was wetter and perhaps warmer than the present day the vertebrate fauna is also noteworthy with species of open habitats such as rabbit oryctolagus cf cuniculus and of closed forest such as squirrel sciurus sp and garden dormouse eliomys quercinus present at different times the occurrence of southern thermophiles such as aesculapian snake zamenis longissimus indicates temperatures warmer than those of eastern england today the upper levels include much material reworked from the interglacial sediments although there is clear faunal evidence for climatic deterioration both the molluscan and vertebrate faunas suggest correlation of the interglacial sediments with the hoxnian uranium series dates from the tufa 455 ka bp tl dates from burnt flints 414 30 ka bp and a range of amino acid racemization data all support correlation of this interglacial with mis 11 however four osl dates from sand beneath the interglacial sequence yield a mean age of 261 31 ka bp far younger than all other age determinations and far younger than implied by the biostratigraphy archaeologically the site is unusual in showing prolonged human occupation within closed deciduous forest and evidence for controlled use of fire in a lower palaeolithic context biostratigraphical correlations with other lower palaeolithic sites support the suggestion that acheulian and clactonian industries both occurred in southern britain during the same substage of the hoxnian although not necessarily at precisely the same time the characteristics of the mis 11 interglacial in britain are discussed in the light of evidence from beeches pit and elsewhere

land sea correlation of middle pleistocene temperate sub stages using high precision uranium series dating of tufa deposits from southern england abstract high precision u series dating allows a direct correlation to be made between terrestrial records of the penultimate interglacial marine oxygen isotope stage 7 mis 7 in britain and sub stage climate forcing in the marine oxygen isotope sequence u series ages of surficial tufa deposits are of sufficient precision to correlate discrete episodes of temperate conditions with individual warm sub stages within mis 7 furthermore detailed biostratigraphy allows periods of faunal turnover to be correlated with cold climates and lowered sea level ecological and environmental conditions in britain during mis 7 are therefore driven by the short lived sub stage climate forcing that is observable in the marine isotope record it is clear that interglacial climates are highly dynamic producing multiple climatic optima and a diverse range of environments within single warm episodes consequently sub stage records of climate forcing are crucial frameworks for reconstructing terrestrial records of environmental change

new constraints on the pb and nd isotopic evolution of ne atlantic water masses 1 time series of lead pb and neodymium nd isotope compositions were measured on three ferromanganese crusts recording the evolution of ne atlantic water masses over the past 15 ma the crusts are distributed along a depth profile 700 4600 m comprising the present day depths of mediterranean outflow water and north east atlantic deep water a pronounced increase of the 206pb 204pb in the two deeper crusts starting at 4 ma and a decrease in 143nd 144nd in all three crusts took place between 6 4 ma and the present these patterns are similar to isotope time series in the western north atlantic basin and are consistent with efficient mixing between the two basins however the changes occurred 1 3 ma earlier in the eastern basin indicating that the northeastern atlantic led the major change in pb and nd isotope composition probably due to a direct supply of labrador seawater via a northern route the pb isotope evolution during the pliocene pleistocene can generally be explained by mixing between two end members corresponding to mediterranean outflow water and north east atlantic deep water but external sources such as saharan dust are likely to have played a role as well the pb isotope composition of the shallowest crust that grew within the present day mediterranean outflow water does not show significant pb isotope changes indicating that it was controlled by the same pb sources throughout the past 15 ma

sedimentology palaeontology and archaeology of late middle pleistocene river thames terrace deposits at purfleet essex uk middle pleistocene fluvial deposits of the corbets tey formation at purfleet essex provide evidence of an un named and previously poorly recognized interglacial thought to corrrelate with oxygen isotope stage ois 9 previous attributions of the sediments to the ipswichian last interglacial stage are refuted new investigations have yielded rich molluscan mammalian and ostracod assemblages that indicate fully temperate conditions and the distal influence of marine transgression pollen analyses suggest a previously unrecorded phase of interglacial vegetational development clast composition geomorphological evidence and the occurrence of molluscs that favour large rivers all point to deposition by the thames rather than in a minor tributary as suggested previously three separate palaeolithic industries in stratigraphical superposition are recognized at purfleet these being clactonian acheulean and levallois purfleet is therefore a key locality in the understanding of the early human occupation and exploitation of southern britain as well as for the interpretation and correlation of the terrace sequence in the thames valley

high potential of calcareous tufas for integrative multidisciplinary studies and prospects for archaeology in europe calcareous tufas are continental carbonates from open air conditions specific to wet and warm periods they contain abundant remains of fauna and flora fossilised in situ and may accumulate regularly over thousands of years offering high stratigraphic resolution for palaeoenvironmental reconstructions as they are mainly comprised of calcite tufas allow direct and precise dating as well as geochemical reconstructions of past climates additionally recent investigations have highlighted their strong potential for archaeology as several studied sequences provided high quality record of in situ prehistoric levels tufas are thus a unique archive in continental areas for development of synergic multidisciplinary investigations of past human societies and associated environmental and climate evolution we emphasise that calcareous tufa are key deposits to investigate human environment climate interactions during interglacial periods from lower palaeolithic to antiquity in europe

a methodological approach for identifying archaeological evidence of fire resulting from human activities abstract the identification of unequivocal evidence of humanly controlled fire is extremely problematic in archaeological contexts where obvious remains such as charcoal and ash have not been preserved until recently the difficulty of identification had been magnified by the lack of an established methodological approach which addressed the problem a methodological approach which can be used to identify and discriminate between archaeological evidence of fire resulting from natural processes and archaeological evidence of fire resulting from human activities is now available the approach utilizes several parameters of investigation including 1 macroscopic examinations of fire feature surfaces and profiles 2 analyses of magnetometer data 3 magnetic susceptibility studies 4 analyses of alternating field demagnetization characteristics 5 studies of isothermal remanent magnetization irm acquisition 6 analyses of coercivity of remanence characteristics and 7 palaeointensity studies the methodological approach is illustrated by comparing the results from analyses of features and samples from grass fire experiment sites isolated tree stump fire experiment sites multiple burn campfire experiment sites modern forest fire sites known archaeological hearths from modoc rock shelter illinois and known archaeological clay ovens from tell ashkelon israel for each available parameter of investigation comparisons revealed that multiple burn campfire sites exhibited basin shaped three dimensional configurations of oxidized sediments and diagnostic magnetic anomalies while multiple burn campfire samples displayed dramatic increases in magnetic susceptibility highly stable to very highly stable responses to alternating field demagnetization dramatic differences in irm acquisition and coercivity of remanence responses and diagnostic palaeointensity results when compared with the responses of adjacent unfired control samples archaeological hearth features and samples and samples from archaeological clay oven features exhibited results which were broadly consistent with the results from multiple burn campfire sites and samples the results displayed by grass fire isolated tree stump fire and forest fire sites and samples were generally found to be mutually exclusive from the results exhibited by multiple burn campfire and archaeological hearth and oven sites and samples for all parameters of investigation the results demonstrate that the methodological approach can be used to unequivocally identify archaeological evidence of humanly controlled fire resulting from multiple burn campfires fire hearths ovens and similar kinds of humanly produced fires

effect of the formation of the isthmus of panama on atlantic ocean thermohaline circulation the late cenozoic closure of the seaway between the north andsouth american continents is thought to have caused extensive changes in ocean circulation and northern hemisphere climate1 2 but the timing and consequences of the emergence of the isthmus of panama which closed the seaway remain controversial1 2 3 4 5 here we present stable isotope and carbonate sand fraction records from caribbean sediments which when compared to atlantic and pacific palaeoceanographic records indicate that the closure caused a marked reorganization of ocean circulation starting 4 6 million years ago shallowing of the seaway intensified the gulf stream and introduced warm and saline water masses to high northern latitudes these changes strengthened deep water formation in the labrador sea over the next million years as indicated by an increased deep water ventilation and carbonate preservation in the caribbean sea and favoured early pliocene warming of the northern hemisphere the evaporative cooling of surface waters during north atlantic deep water formation would have introduced moisture to the northern hemisphere although the pronounced intensification of northern hemisphere glaciation between 3 1 and 2 5 million years ago substantially lagged the full development of north atlantic deep water formation we propose that the increased atmospheric moisture content was a necessary precondition for ice sheet growth which was then triggered by the incremental changes in the earth s orbital obliquity

rare earth element transport in the western north atlantic inferred from nd isotopic observations the isotopic composition of nd in the water column from several western north atlantic sites and formational areas for north atlantic deep water shows extensive vertical structure at all locations in regions where a thermocline is well developed large isotopic shifts 2 to 3 units are observed across the base of the thermocline regions without a thermocline are characterized by much more gradual shifts in isotopic composition with depth in general the data reveal an excellent correlation between the nd isotopic distribution in the western north atlantic water column and the distribution of water masses identified from temperature and salinity characteristics nadw as identified from t s properties is also characterized by a well defined isotopic composition having nd 0 13 5 0 5 this signature is associated with waters identified as nadw from high latitudes near formational areas in the labrador sea down to the equatorial region the isotopic signature of nadw would appear to be formed by a blend of more negative waters originating in the labrador sea nd 0 18 and more positive waters originating in the overflows from the norwegian and greenland seas nd 0 8 to 10 and is consistent with classical theories on the formation of nadw the isotopic signature of nadw is propagated southward to the equator where it is gradually being thinned out by mixing from above and below with more radiogenic nd associated with northward spreading antarctic intermediate and bottom waters the preservation of the isotopic signature of nadw over these large distances indicate that the ree undergo extensive lateral transport the isotopic composition of nd is largely conservative over the time scales of mixing within the atlantic in spite of the intrinsic nonconservative behavior of neodymium nd concentration gradients generally show surface waters to be depleted in nd relative to deep waters which must require vertical transport processes however isotopic differences in the water column preclude the local downward transport of ree from the surface into underlying deep waters as a simple explanation of the concentration gradient the apparent decoupling of ree in nadw from overlying local surface waters and the increasing concentration with depth provide a conflict with simple vertical transport mechanisms that is not yet resolved

role of panama uplift on oceanic freshwater balance comparison between planktic foraminiferal oxygen isotope records from the caribbean sea ocean drilling program odp site 999 and the equatorial east pacific odp site 851 suggests an increase in caribbean surface water salinity between 4 7 and 4 2 ma the modern atlantic pacific salinity contrast of about 1 became fully established at 4 2 ma as reflected by a 0 5 planktic foraminifera 18o enrichment in the caribbean sea this is interpreted as the result of restricted surface water exchange between the tropical atlantic and pacific in response to the shoaling of the central american seaway as a consequence the atlantic and pacific surface ocean circulation regime changed as did the freshwater balance between the major ocean basins simultaneous shifts in benthic carbon isotope records in the caribbean sea suggest an intensification in north atlantic thermohaline circulation these results indicate that the panamanian isthmus formation caused several new ocean atmosphere feedback mechanisms that have affected climate since the early pliocene

ostracod based palaeotemperature reconstructions for mis 11 human occupation at beeches pit west stow suffolk uk abstract the mutual ostracod temperature range motr method is applied to ostracod assemblages from the well documented middle pleistocene mis 11 human occupation site of beeches pit west stow suffolk england the results provide palaeotemperature reconstructions which are compared against other proxy data from molluscs and ostracod indicator species ostracod assemblages from the lower part of the sequence beds 3 and 4 suggest a temperate climate with mean monthly temperatures january and july not dissimilar to those of today while those of the overlying bed 7 indicate a climatic shift to a more continental climate with winter temperatures at least 4 c colder than today these results corroborate previous suggestions that the evidence of human occupation at beeches pit occurs not only in the interglacial mis 11c but also in a succeeding cold phase possibly mis 11b and provide the first quantitative palaeotemperature reconstructions for this site and interval