large scale dynamics of the mesosphere and lower thermosphere an analysis using the extended canadian middle atmosphere model the extended canadian middle atmosphere model is used to investigate the large scale dynamics of the mesosphere and lower thermosphere mlt it is shown that the 4 day wave is substantially amplified in southern polar winter in the presence of instabilities arising from strong vertical shears in the mlt zonal mean zonal winds brought about by parameterized nonorographic gravity wave drag a weaker 4 day wave in northern polar winter is attributed to the weaker wind shears that result from weaker parameterized wave drag the 2 day wave also exhibits a strong dependence on zonal wind shears in agreement with previous modeling studies in the equatorial upper mesosphere the migrating diurnal tide provides most of the resolved westward wave forcing which varies semiannually in conjunction with the tide itself resolved forcing by eastward traveling disturbances is dominated by smaller scales nonmigrating tides and other planetary scale waves play only a minor role in the zonal mean zonal momentum budget in the tropics at these heights resolved waves are shown to play a significant role in the zonal mean meridional momentum budget in the mlt impacting significantly on gradient wind balance balance fails at low latitudes as a result of a strong reynolds stress associated with the migrating diurnal tide an effect which is most pronounced at equinox when the tide is strongest resolved and parameterized waves account for most of the imbalance at higher latitudes in summer this results in the gradient wind underestimating the actual eastward wind reversal by up to 40

isotope systematics and shock wave metamorphism iii k ar in experimentally and naturally shocked rocks the haughton impact structure canada this is a report on the first comparative study of the effects of experimental and natural shock on the k ar system first mineral separates from a 451 plus minus 1 ma old gneiss experimentally shocked up to 60 gpa were investigated by stepwise heating sup 40 ar sup 39 ar technique compared with an unshocked samples the shocked samples have lower sup 40 ar sup 39 ar ages and the diffusion properties have changed depending on peak shock pressure and mineralogic composition total resetting of the k ar clock did not occur secondly to compare these results with the effects of natural shock samples from the approximately 23 ma old haughton impact crater devon island canada with different shock stages were investigated up to shock stage 3 no total resetting of the k ar clock was observed but severe argon losses depending on shock pressure result in sup 40 ar sup 39 ar plateau ages which are incorrect in terms of the true crater age yet they provide an upper limit to the time of the cratering event

isotope systematics and shock wave metamorphism i u pb in zircon titanite and monazite shocked experimentally up to 59 gpa this study reports the first u pb isotope analyses on experimentally shocked zircon titanite and monazite extracted from proterozoic granitoid rocks in all three types of minerals shock waves produce drastic changes in the crystal lattices causing strong lowering of birefringence turbidization and decolorization of the individual grains moreover x ray patterns indicate transition of the crystals into polycrystalline aggregates of 10 5 mm block size precisely dated grains with concordant or nearly concordant ages were embedded in kbr and shocked at 35 47 5 and 59 gpa u pb isotope analyses on these grains show that shock metamorphism does not fractionate pb isotopes within the analytical precision of 0 1 as far as chemical fractionation is concerned there is no difference in degree of concordancy between shocked and unshocked monazite and small degrees 2 of relative upb fractionation in shocked zircon and titanite are due to time integrated pb loss and not to the shock experiment in consequence the data document that shock wave metamorphism alone does not measurably effect the u pb chronometer questioning the view that lower intercept ages of discordant u pb data reflect shock induced re equilibration of the chronometer in moderately to highly shocked rapidly cooling rocks

investigating experimental knapping damage on an antler hammer a pilot study using high resolution imaging and analytical techniques organic bone antler wood knapping tools were undoubtedly a component of early human tool kits since the lower palaeolithic previous studies have identified pitting and the occasional presence of embedded flint flakes as important features for recognizing archaeological bone and antler percussors however no systematic protocol of analysis has been suggested for the study of this rare archaeological material here we present qualitative and quantitative results of a preliminary analysis of an experimental knapping hammer using a novel combination of microscopy focus variation optical microscope and scanning electron microscope micro ct scanning and energy dispersive x ray spectroscopy these imaging and analytical techniques are used to characterize use damage from the manufacture of handaxes this paper highlights the strengths and weakness of each technique use wear on the working area included attritional bone loss micro striations and compaction of the outer layer of the antler matrix from repeated hitting of the beam against the sharp edge of the handaxe during knapping embedded flint flakes were also identified in the pits and grooves this combination of high resolution imaging techniques is applicable to fragile archaeological specimens including those encrusted by sediment or encased in matrix

fission track dating of haughton astrobleme and included biota devon island canada haughton astrobleme is a major extraterrestrial impact structure located on devon island in the canadian arctic archipelago northwest territories apatite grains separated from shocked precambrian gneiss contained in a polymict breccia from the center of the astrobleme yielded a fission track date of 22 4 million 1 4 million years before the present or early miocene aquitanian this provides a date for the impact event and an upper limit on the age of crater filling lake sediments and a flora and vertebrate fauna occurring in them a geologically precise date for these fossils provides an important biostratigraphic reference point for interpreting the biotic evolution of the arctic

the problem of inherited 40ar in dating impact glass by the 40ar 39ar method evidence from the tswaing impact crater south africa abstract the tswaing meteorite impact crater is a 1 13 km diameter structure located in the 2 05 ga nebo granite of the bushveld complex the impact age had previously been determined by fission track dating to 220 104 ka 40ar 39ar step heating and total fusion experiments performed on single and multi grain impact glass aliquots gave apparent ages ranging from 1 0 0 3 ma to 204 6 ma these ages indicate that the radiogenic ar derived from the target rocks has not been completely degassed as a result of the impact process despite fusion of the target material results of step heating experiments imply that the 40 ar inherited trapped within the glass is located in two distinct reservoirs thought to be the glass matrix and fluid vapor inclusions or un melted residual clasts calculations assuming an age of 0 2 0 1 ma for tswaing fission track data reveal that the amount of inherited 40ar 40 ar inherited relative to the pre impact concentration varies from 0 015 to 4 15 the spread defined by 40 ar inherited likely reflects the various quench rates experienced by the glass most certainly due to the pre impact position of the sample relative to the center of the crater we compare the influence of 40 ar inherited on the apparent 40ar 39ar age determination of five impact structures our calculations show that the main characteristic controlling the age offset for a given proportion of 40 ar inherited is the age difference between the impact and the target rocks i e the 40ar concentration in the target rock the buffer effect for a given crater structure can be predicted knowing the age of the basement and having a rough estimation of the age of the crater structure itself the occurrence of 40 ar inherited is likely influenced by 1 the degree of polymerization i e silicate structure complexity of the target rock and presumably related to the diffusivity of ar in the melt and glass 2 the ar partial pressure at the grain boundary 3 the quantity of energy involved in the impact and 4 the porosity of the target rocks for glass that inevitably suffers inherited and or excess 40ar the use of the inverse isochron technique can be appropriate but should be applied with careful statistical treatment

a late middle stone age artifact assemblage from sibudu kwazulu natal comparisons with the european middle paleolithic abstract it has been suggested that many behavioral innovations said to appear during the late middle stone age in sub saharan africa facilitated the expansion of anatomically modern humans from africa and the near east into europe at about 50 kyr the process eventually led to the replacement of neanderthals by modern humans and the emergence of the upper paleolithic however assemblages in this time range are little known in south africa in fact the transition from middle to the later stone age in southern africa is controversial the early appearance in south africa of many innovations such as sophisticated knapping techniques e g the use of soft hammer or indirect percussion in blade production of composite tools of microlithic and bladelet technologies remains to be established through technological analysis we present here the first results of a project designed to carry out detailed technological studies of several lithic assemblages in south africa and france dated to the transition period at this time we have completed the study of a post howiesons poort assemblage from the rock shelter site of sibudu the 2 m deep stratigraphic sequence of sibudu extends from howiesons poort at its base to final middle stone age directly under iron age layers we have analyzed in detail layer rsp ca 53 kyr 1 m above the howiesons poort levels which has provided a large assemblage of several thousand stone artifacts compared to published msa assemblages this industry is unusual for the very high proportions of retouched pieces 15 the technology is not very elaborate and there is no strong standardization of the end products there are no flakes of predetermined shapes retouch is used to modify irregular flakes to obtain desired edges knapping of flakes and blades is done by hard hammer soft hammer is used only for retouching tools interestingly the older howiesons poort blades were produced on the same raw materials by soft hammer raw material hornfels and dolerite was procured from distances of less than 20 km unifacial points are the dominant type and there is strong evidence of hafting and use as spear armatures detailed comparisons with middle paleolithic assemblages of western europe show that the late middle stone age technology in south africa is very similar to that of the middle paleolithic in fact we see no fundamental differences between the two entities as far as lithic technology is concerned implications for the out of africa hypothesis are discussed

chronology of the youfang site and its implications for the emergence of microblade technology in north china abstract the youfang paleolithic site located in the eastern nihewan basin hebei province china was discovered in 1984 however the microblade assemblages which were excavated from the site lacked reliable chronological data in this study an optical dating technique was applied to nine samples from late pleistocene eolian sequences at the site the ages of three samples from artifact bearing deposits were in the range of ca 26 29 ka with depths between 2 1 m and 2 9 m obtained with medium grained quartz corresponding to marine isotope stage 3 mis3 these displayed evidence of a longer term climate trend in which the climate became gradually warmer and more humid the sample from the upper culture layer was dated to 26 4 2 1 ka five samples taken from the lower culture layer yielded ages between ca 28 ka and 43 ka the results suggest that human occupation at the youfang site ranged from ca 26 ka to 29 ka indeed the nihewan basin yields the oldest microblade site in northern high latitudes 40 n and offers a unique opportunity to study the emergence and characteristics of microblade technologies in northeast asia nevertheless extensive archeological field surveys and excavations are still needed to understand further the developmental process of microblade technologies in the region

analysis of the xiaonanhai lithic assemblage excavated in 1978 abstract an analysis of the lithic artifacts excavated by the late mr zhimin an in 1978 from the xiaonanhai hsiao nan hai cave site in anyang county henan province is presented in addition to the materials reported in 1965 from the first excavation analysis suggests the poor quality of the raw material e g chert was a major constraint on lithic production at xiaonanhai highly developed fissures within the locally available chert resulted in lithic artifacts that are small in size hard hammer direct percussion was the primary mode of stone knapping the bipolar technique was commonly used as well which might have been employed to cope with the small poor quality raw materials secondary retouch is simple and not sophisticated limited tool types could be classified most are probably debitage or discarded blanks use wear analysis indicates that most of the flakes were used to process soft materials based on the associated faunal diversity the environment is characterized as a tropical subtropical forest this could be the reason for the expedient nature of lithic production at xiaonanhai the xiaonanhai industry might not be related to the zhoukoudian locality 1 stone tool industry as traditionally thought but instead may represent a specific adaptation to the local environment in terms of what is currently known about the nature of paleolithic stone tool technology in china the unilinear model is no longer relevant to explain the paleolithic development in north china in order to better understand the complexity and diversity of human behavior study of the adaptation and idiosyncrasy of specific lithic industries in terms of cultural ecology and how they reflect variability in time stress and risks is required

re evaluating the age of the haughton impact event we have re evaluated the published age information for the haughton impact structure which was believed to have formed 23 ma ago during the miocene age and report new ar ar laser probe data from shocked basement clasts this reveals an eocene age which is at odds with the published miocene stratigraphic apatite fission track and ar ar data we discuss our new data within this context we have found that the age of the haughton impact structure is 39 ma which has implications for both crater recolonization models and post impact hydrothermal activity future work on the relationship between flora and fauna within the crater and others at high latitude may resolve this paradox

the shuidonggou site complex new excavations and implications for the earliest late paleolithic in north china the initial late paleolithic said to appear between 40 and 30 kya in eastern asia is defined by the appearance of many innovations these archaeological indicators include the appearance of more refined stone tool making techniques e g include the appearance of blade and microblade technology complex hearth construction use of pigments and personal ornamentation as well as worked faunal implements such as bone and antler tools we report here new findings from a multidisciplinary research project conducted at the shuidonggou choei tong keou site complex in northern china a series of localities that date from the initial late paleolithic to the neolithic six new localities sdg7e12 were discovered and five localities sdg2 previously identified and sdg7e9 and 12 were excavated yielding more than 50 000 stone artifacts fauna ostrich eggshell beads and hearths dating results suggest that human occupation of the shuidonggou area occurred during the late pleistocene to middle holocene w32 000e6000 bp some sites are characterized by small irregular flakes casually retouched tools modified or informally retouched tools i e non standardized tools with sporadic retouch which was not well controlled and small numbers of blades or no blades others lithic assemblages are dominated by blades and microblades at two sites higher quality or exotic raw materials were exploited but at the majority of sites locally available river cobbles were used in addition to blades microblades and hearths more than 80 finely perforated and polished ostrich eggshell beads mostly colored with red ochre were recovered from three sites several worked bone needles and an awl were also uncovered from the youngest site sdg12 in deposits dating to c 13 000 cal bp the implications for the initial appearance of the late paleolithic in china and movement of modern human populations into north china are discussed

extended canadian middle atmosphere model zonal mean climatology and physical parameterizations 1 this paper describes the energetics and zonal mean state of the upward extension of the canadian middle atmosphere model which extends from the ground to 210 km the model includes realistic parameterizations of the major physical processes from the ground up to the lower thermosphere and exhibits a broad spectrum of geophysical variability the rationale for the extended model is to examine the nature of the physical and dynamical processes in the mesosphere lower thermosphere mlt region without the artificial effects of an imposed sponge layer which can modify the circulation in an unrealistic manner the zonal mean distributions of temperature and zonal wind are found to be in reasonable agreement with observations in most parts of the model domain below 150 km analysis of the global average energy and momentum budgets reveals a balance between solar extreme ultraviolet heating and molecular diffusion and a thermally direct viscous meridional circulation above 130 km with the viscosity coming from molecular diffusion and ion drag below 70 km radiative equilibrium prevails in the global mean in the mlt region between 70 and 120 km many processes contribute to the global energy budget at solstice there is a thermally indirect meridional circulation driven mainly by parameterized nonorographic gravity wave drag this circulation provides a net global cooling of up to 25 k d 1

tracing the source of upper palaeolithic shell beads by strontium isotope dating abstract while the identification of the source of shells used as personal ornaments is crucial for determining home range and exchange networks of prehistoric hunter gatherers it is often difficult to identify the coastal versus fossil origin of the shells as most genera used as beads were available both at beaches and fossil outcrops here we present the first application of 87sr 86sr isotope dating to identify the origin of upper palaeolithic shell beads we analysed four out of a collection of one thousand dentalium shells associated to the la madeleine child burial dated to 10 190 100 bp and one dentalium from the occupation layers of this site 87sr 86sr ratios indicate that shells were collected by late upper palaeolithic beadworkers on far away beaches rather than at nearer miocene outcrops this may be due to the narrowness of miocene dentalium shells incompatible with the size of bone needles used to sew these shell beads on clothes

new ages for the post howiesons poort late and final middle stone age at sibudu south africa abstract optically stimulated luminescence osl measurements are reported for single grains of quartz from deposits within sibudu rock shelter such measurements enable rejection of unrepresentative grains and application of the finite mixture and central age models to obtain the most reliable age estimates three types of single grain equivalent dose de distributions were observed one sample represented a single dose population three samples indicated mixing between iron age ia and middle stone age msa deposits and 10 samples in addition to the three mixed samples showed scattered distributions the latter type resulted from differences in the beta dose received by individual grains for these samples the beta doses were modelled and adjusted accordingly ages for the 14 samples collected from msa deposits post dating the howiesons poort hp resulted in three age clusters which are stratigraphically consistent with the three informally named cultural phases at sibudu namely the post hp late msa and final msa weighted mean ages of 58 5 1 4 ka 47 7 1 4 ka and 38 6 1 9 ka were calculated for these phases respectively the three phases were separated by two occupational hiatuses with durations of 10 8 1 3 ka and 9 1 3 6 ka we hypothesise that the punctuated presence of humans at sibudu was determined by large scale fluctuations in climate during oxygen isotope stage ois 3 which resulted in alternating wet and dry periods phases of occupation correspond to wet periods when fresh water was available in the tongati river whereas intervals of site abandonment correspond to dry periods when people were forced to migrate in search of a reliable source of fresh water where people migrated to remains unresolved

shock effects on the k ar system of plagioclase feldspar and the age of anorthosite inclusions from north eastern minnesota abstract artificial shock pressures up to 52 5 gpa have no influence on the k ar system of plagioclase feldspar the 40ar 39ar analysis of feldspar labradorite an67 from anorthosite of north eastern minnesota shocked up to 45 gpa in vacuo to prevent massive entrapment of atmospheric argon shows that the age spectra and the argon diffusion properties remain unaltered similar feldspar samples labradorite an51 from nain labrador shocked in air up to 52 5 gpa and dated by the conventional k ar method also yield the same age as unshocked samples but with a higher atmospheric argon contribution the minnesota anorthosite has an 40ar 39ar age of 1075 10 m y no information on a possible previous history of the anorthosite became apparent

surface modification on bone trampling versus butchery abstract previous researchers have reported difficulties in distinguishing between surface marks on bone formed by sedimentary abrasion and those inflicted while butchering trampling by large ungulates and humans has been credited with producing pseudocut marks natural alterations to the bone that mimic cultural ones the purposes of this research are 1 to re examine trampling as a taphonomic process and 2 to suggest criteria useful for distinguishing sedimentary abrasion including trampling from butchery macroscopic and microscopic comparison of experimentally trampled bones and those which have had soft tissue removed with a flint tool demonstrate significant differences between the surface modifications produced by the two processes

geological overview and cratering model for the haughton impact structure devon island canadian high arctic the haughton impact structure has been the focus of systematic multi disciplinary field and laboratory research activities over the past several years regional geological mapping has refined the sedimentary target stratigraphy and constrained the thickness of the sedimentary sequence at the time of impact to 1880 m new 40ar 39ar dates place the impact event at 39 ma in the late eocene haughton has an apparent crater diameter of 23 km with an estimated rim final crater diameter of 16 km the structure lacks a central topographic peak or peak ring which is unusual for craters of this size geological mapping and sampling reveals that a series of different impactites are present at haughton the volumetrically dominant crater fill impact melt breccias contain a calcite anhydrite silicate glass groundmass all of which have been shown to represent impact generated melt phases these impactites are therefore stratigraphically and genetically equivalent to coherent impact melt rocks present in craters developed in crystalline targets the crater fill impactites provided a heat source that drove a post impact hydrothermal system during this time haughton would have represented a transient warm wet microbial oasis a subsequent episode of erosion during which time substantial amounts of impactites were removed was followed by the deposition of intracrater lacustrine sediments of the haughton formation during the miocene present day intracrater lakes and ponds preserve a detailed paleoenvironmental record dating back to the last glaciation in the high arctic modern modification of the landscape is dominated by seasonal regional glacial and niveal melting and local periglacial processes the impact processing of target materials improved the opportunities for colonization and has provided several present day habitats suitable for microbial life that otherwise do not exist in the surrounding terrain

a newly discovered antler flint knapping hammer and the question of their rarity in the palaeolithic archaeological record reality or bias abstract the use of soft bone antler tooth and wood hammers and retouchers is a key innovation in early stone tool technology first appearing in the archaeological record with lower palaeolithic handaxe industries e g boxgrove uk 500 ka although organic knapping tools were undoubtedly a component of early human toolkits and are essential for example for the manufacture of finely flaked handaxes mousterian scrapers and upper palaeolithic blades tools such archaeological finds are exceptionally rare in this study we present qualitative and quantitative analyses focus variation optical microscope scanning electron microscope micro ct scanning and energy dispersive x ray spectroscopy of a newly discovered antler flint knapping from laugerie haute west france this specimen was originally identified as a waste product from splinter manufacture and the use damage appears to have been overlooked by earlier workers the new analysis shows that prior to being used as a flint knapping percussor the red deer antler had been modified to reduce the length of its beam and to remove the tines although minimally used characteristic use damage includes attrition pits and scores compression of the antler matrix and flint chips embedded within some of the percussion features on the base of the burr an ams radiocarbon date of 12 385 55 bp 12 647 335 bc calibrated confirms a magdelenian context for the hammer the fact that the laugerie haute knapping hammer went unrecognised in a well studied and accessible collection where it was stored for almost 200 years suggests that antler hammers may be more common than generally assumed only further re examination of prehistoric antlers in museum collections will confirm whether the apparent rarity of antler hammers during the lower and middle palaeolithic is real phenomenon or the result of analytical biases

recycling bones in the middle pleistocene some reflections from gran dolina td10 1 spain bolomor cave spain and qesem cave israel abstract archaeologists can use different kinds of data to identify recycling however most approaches to recycling are based on lithic artefact attributes especially on surface alterations suggesting a period of discard between different events recycling can also be approached by means of faunal remains based on bone damage characteristics bone breakage processes aimed at maximizing the nutritional value of consumed animals generate a high number of small and large sized fragments which are eventually discarded some of these are morphologically suitable for human use it is necessary to distinguish between the use of bone as raw material from pre existing very large sized carcasses such as elephants in cases where it is not certain if these had a nutritional purpose and the recycling of fragments resulting from bone marrow extraction of smaller mammals that were obtained and consumed by human groups in the first case when the bones of a pre existing elephant including natural deaths are exploited for tool making the bones can be considered raw material very similar to collecting stones as raw material for the lithic industry in the second case the bones of smaller mammals are selected to be used in a subsequent life cycle after being broken for nutritional purposes and discarded here we present some early cases of recycled bones from the middle pleistocene sites of gran dolina td10 1 and bolomor cave in spain and qesem cave in israel the studied elements appear to have been part of a previous faunal processing sequence nutritional in nature which were later discarded and then used or modified for purposes other than the original ones these fragments are dated to mis 9 and show damage produced by use retouched and unmodified soft retouchers or shaped forms bone artefacts this study is an attempt to provide new data on recycling activities of faunal remains in the middle pleistocene and discuss the origin of this behaviour

luminescence dating at katanda a reassessment abstract a luminescence date of 80 ka for sediments associated with bone harpoon points recovered at katanda in east africa has been reassessed using additional samples an original problem with radiation quenching has been overcome by using a higher preheat single aliquot analyses suggest sufficient bleaching new osl dates while scattered support the original date and the antiquity of the site

shock effects and argon loss in samples of the leedey l6 chondrite experimentally shocked to 29 70 ga pressures abstract shock recovery experiments between 29 and 70 gpa were made on the leedey l6 chondrite to determine the possible loss of radiogenic ar caused directly by passage of shock waves as opposed to purely thermal loss during prolonged post shock cooling experiments were made in vacuum to prevent shock implantation of terrestrial air and following neutron irradiation the 39 ar 40 ar ratios were measured by stepwise temperature release petrographie examination of experimentally shocked leedey showed predominantly solid state effects in the form of increasing disaggregation of component minerals with increasing shock pressure but very little melting even at the highest shock levels the melting behavior of the minor feldspar phase was difficult to document but likely was complete by the higher shock levels the 39ar 40ar release patterns were complex for both shocked and reference leedey probably because of a natural shock history for the meteorite at ca 3 8 gy the average 39ar 40ar age for shocked leedey decreased with increasing shock levels from essentially no change at 29 gpa to a 20 decrease in age at 60 gpa the feldspar phases degas at lower extraction temperatures and show even greater lowering of 39ar 40ar age with increasing shock pressure the sample shocked at 69 gpa shows less mechanical disruption than samples shocked to lesser pressures and also shows a smaller loss of ar compared to samples shocked at 45 and 60 gpa we conclude that observed ar loss is caused by extensive grain fracturing and heating during shock and that greater ar loss at low extraction temperatures is enhanced by feldspar melting none of the experiments duplicated the magnitude of ar loss commonly seen in naturally shocked materials that lack evidence of pervasive melting we conclude that large scale gas loss in shocked but unmelted samples requires that the materials reside for prolonged periods of time at elevated temperatures in a relatively hot impact formation either inside or outside the crater cavity

bone needle fragment in lgm from the shizitan site china archaeological evidence and experimental study an eyed bone needle fragment found in shizitan 29 site shanxi province dated to ca 23 26 ka cal bp is one of the early needles with a precise stratigraphic context and date among the open air palaeolithic sites in north china although the needle was found broken based on microwear observation and experiments in making and using bone needles we conclude that it had been used for sewing further archaeological evidence including a sandstone needle shaping stone drilling tools perforated ornaments and microscopic evidence of thread support the presence of a bone needle at the shizitan 29 site it was the same type as the bone needles used in siberia during the late pleistocene and the use of needles at shizitan was one of the strategies for making warm clothes to adapt to the coming of the last glacial maximum lgm 24 000 18 000 cal bp

polar mesosphere and lower thermosphere dynamics 1 mean wind and gravity wave climatologies 1 mean wind and gravity wave climatologies are presented for the polar mesosphere and lower thermosphere mlt the data were derived using mf radars at davis 69 s 78 e and syowa 69 s 40 e in the antarctic and poker flat 65 n 147 w and andenes 69 n 16 e in the arctic the dynamics of the antarctic mlt are found to be significantly different from the arctic mlt summer maxima in both the westward and equatorward winds occur closer to the solstice in the antarctic than in the arctic the greater symmetry around the solstice suggests radiative effects may play a greater role in controlling the state of the antarctic mlt than in the arctic where dynamical effects appear to be more important gravity wave observations also suggest that wave drag may be greater in the arctic than in the antarctic the equatorward flow near the mesopause persists later in summer in the arctic than in the antarctic as do observations of polar mesospheric clouds and polar mesospheric summer echoes all three phenomena begin at about the same time in each hemisphere but end later in the arctic than in the antarctic it is proposed that the magnitude of the meridional winds can be used as a proxy for gravity wave driving and the consequent adiabatic cooling in the mlt seasonal variations in gravity wave activity are predominately combinations of annual and semiannual components significant hemispheric differences are observed for both the timing and magnitude of these seasonal variations

the periglacial climate and environment in northern eurasia during the last glaciation this paper summarizes the results of studies of the late weichselian periglacial environments carried out in key areas of northern eurasia by several queen teams european science foundation esf programme quaternary environment of the eurasian north the palaeoglaciological boundary conditions are defined by geological data on timing and extent of the last glaciation obtained in the course of the eu funded project eurasian ice sheets these data prove beyond any doubt that with the exception of the northwestern fringe of the taymyr peninsula the rest of the eurasian mainland and severnaya zemlya were not affected by the barents kara sea ice sheet during the last glacial maximum lgm inversed modelling based on these results shows that a progressive cooling which started around 30 ka bp caused ice growth in scandinavia and the northwestern areas of the barents kara sea shelf due to a maritime climate with relatively high precipitation along the western flank of the developing ice sheets in the rest of the eurasian arctic extremely low precipitation rates less than 50 mm yr 1 did not allow ice sheet growth in spite of the very cold temperatures palaeoclimatic and palaeoenvironmental conditions for the time prior to during and after the lgm have been reconstructed for the non glaciated areas around the lgm ice sheet with the use of faunal and vegetation records permafrost eolian sediments alluvial deposits and other evidences the changing environment from interstadial conditions around 30 ka bp to a much colder and drier environment at the culmination of the lgm at 20 15 ka bp and the beginning of warming around 15 ka bp have been elaborated from the field data which fits well with the modelling results

stratigraphic placement and age of modern humans from kibish ethiopia in 1967 the kibish formation in southern ethiopia yielded hominid cranial remains identified as early anatomically modern humans assigned to homo sapiens however the provenance and age of the fossils have been much debated here we confirm that the omo i and omo ii hominid fossils are from similar stratigraphic levels in member i of the kibish formation despite the view that omo i is more modern in appearance than omo ii 40ar 39ar ages on feldspar crystals from pumice clasts within a tuff in member i below the hominid levels place an older limit of 198 14 kyr weighted mean age 196 2 kyr on the hominids a younger age limit of 104 7 kyr is provided by feldspars from pumice clasts in a member iii tuff geological evidence indicates rapid deposition of each member of the kibish formation isotopic ages on the kibish formation correspond to ages of mediterranean sapropels which reflect increased flow of the nile river and necessarily increased flow of the omo river thus the 40ar 39ar age measurements together with the sapropel correlations indicate that the hominid fossils have an age close to the older limit our preferred estimate of the age of the kibish hominids is 195 5 kyr making them the earliest well dated anatomically modern humans yet described

impact induced phase transformations at 50 60 gpa in continental crust an epma and atem study strongly shocked gneiss fragments from the allochthonous polymict breccia of the 23 ma old haughton impact crater were studied by optical microscopy electron probe microanalysis epma and analytical transmission electron microscopy atem the study is focused on the substantiation of shock induced phase transformations in rock forming minerals and their implications for post shock thermal regimes and impact age dating in the gneiss fragments the original layering is largerly preserved although all the minerals have experienced dramatic phase transformations chemically the various shock generated decomposition regions still reflect the pre shock mineralogy however significant heterogeneities exist on the 10 100 m scale four different regions of decomposition products can be distinguished epma 1 shocked biotite rich regions with strong variations in si al k fe and mg on the 10 m scale 2 shocked quartz with about 3 al and k and traces of fe and mg 3 a region with al si 1 which does not correspond to any pre shock mineral and 4 shocked k feldspar showing a significant deficit in k and traces of fe and mg on the nanometer scale a uniform bimodal reaction pattern emerges all minerals are transformed to new crystals embedded in a silica rich glass the shock generated crystals are 1 spinel in shocked biotite 2 quartz cristobalite and coesite in shocked quartz 3 an unknown polymorph of corundum al2o3 in feldspar and in the al si 1 region and 4 mullite in association with sio2 glass in shocked sillimanite grains all crystals range in size between 0 05 and 1 0 m taking into account estimated durations and pressure temperature conditions for shock wave passage and post shock temperatures the reactions observed can be ascribed to high temperatures during and after pressure release the different mineral glass parageneses suggest temperatures in excess of 1400 c moreover given the small size of the newly formed minerals very rapid cooling down to 1200 c is required

the use of lithic raw materials during the upper paleolithic in eastern china a focus on microblade industries abstract during the upper paleolithic many sites with microblade industries were distributed across northeastern china and the north china plain in eastern china based on the composition of lithic raw materials lrms and the site distributions of microblade industries this study defined five territories of human groups in two regions of china 1 the western changbai shan mountains mount paektu and song nen plain in northeastern china and 2 the southern yanshan mountains yi shu river basin and western huang huai plain in the north china plain in northeastern china high quality lrms including various types of igneous rock and obsidian were used in combination with local lrms such as flint and agate based on the distribution range of high quality lrms the territories of human groups in that region are estimated at 300 450 km it is believed that residential systems were established for the long distance transport of lrms and the long distance movement of human groups one such system included microblade technology based on biface and flake blade reduction systems in contrast the territory of human groups in the north china plain was small with an area estimated at 100 230 km given the numerous small sites in that region it is believed that human groups moved frequently within their territories because they were highly mobile and dependent on local lrm sources e g flint near their occupation sites human groups might have employed various microcore reduction systems to produce microblades even from limited lrms preliminary conclusions suggest that the divergent activities of late upper paleolithic human groups in eastern china could reflect variations in regional economic strategies and ecological environments between the last glacial maximum and the younger dryas

middle stone age bone tools from the howiesons poort layers sibudu cave south africa abstract recently discovered bone implements from middle stone age msa deposits at sibudu cave south africa confirm the existence of a bone tool industry for the howiesons poort hp technocomplex previously an isolated bone point from klasies river provided inconclusive evidence this paper describes three bone tools two points and the end of a polished spatula shaped piece from unequivocal hp layers at sibudu cave with ages greater than 61 ka comparative microscopic and morphometric analysis of the sibudu specimens together with bone tools from southern african middle and later stone age lsa deposits an iron age occupation nineteenth century bushman hunter gatherer toolkits and bone tools used experimentally in a variety of tasks reveals that the sibudu polished piece has use wear reminiscent of that on bones experimentally used to work animal hides a slender point is consistent with a pin or needle like implement while a larger point reminiscent of the single specimen from peers cave parallels large un poisoned bone arrow points from lsa iron age and historical bushman sites additional support for the sibudu point having served as an arrow tip comes from backed lithics in the hp compatible with this use and the recovery of older larger bone and lithic points from blombos cave interpreted as spear heads if the bone point from the hp layers at sibudu cave is substantiated by future discoveries this will push back the origin of bow and bone arrow technology by at least 20 000 years and corroborate arguments in favour of the hypothesis that crucial technological innovations took place during the msa in africa

39ar 40ar dating of mesosiderites evidence for major parent body disruption 4 ga ago 39ar 40ar ages were measured on 17 samples of 14 different mesosiderites and indicate major degassing of ar by one or more thermal events less than 4 0 ga ago three samples gave release patterns of constant age whereas the other samples typically showed 200 400 ma increases in 39ar 40ar age with increasing gas extraction temperature these stepwise releases indicate ages of 3 4 3 8 ga 1 ga 109 a averaged ages for individual meteorites are 3 45 3 82 ga no substantial evidence exists in the temperature releases for 39ar 40ar ages older than 4 0 ga and the ar ages appear to be in contradiction to 244pu fission track ages previously reported for a few mesosiderites the ar ages probably date the event that caused disturbance in previously reported rb sr sm nd and pb pb ages of estherville and other mesosiderites data on release of ar as a function of extraction temperature were used in arrhenius plots to estimate activation energies for ar diffusion of 18 52 kcal mol these values were then used to calculate closure temperatures against ar loss of 2 340 c and 180 600 c for assumed cooling rates of 1 c ma and 1 c a respectively the ar data suggest that for certain assumed models of mesosiderite formation the 39ar 40ar ages may date the time of formation of those metal textures in mesosiderites which have led others to calculate cooling rates of 1 c ma models which call for metal silicate mixing 4 5 ga ago followed by cooling at 1 c ma from temperatures 1150 c seem unlikely single event models which produce the silicate metal mixture at high temperatures rapidly cool the objects to temperatures of 500 c followed by cooling of 1 c ma and are not consistent with the ar data unless the thermal event occurred 500 c and left them deeply buried to undergo slow cooling

southern hemisphere summer mesopause responses to el nino southern oscillation abstractin the southern hemisphere sh polar region satellite observations reveal a significant upper mesosphere cooling and a lower thermosphere warming during warm enso events in december an opposite pattern is observed in the tropical mesopause region the observed upper mesosphere cooling agrees with a climate model simulation analysis of the simulation suggests that enhanced planetary wave pw dissipation in the northern hemisphere nh high latitude stratosphere during el nino strengthens the brewer dobson circulation and cools the equatorial stratosphere this increases the magnitude of the sh stratosphere meridional temperature gradient and thus causes the anomalous stratospheric easterly zonal wind and early breakdown of the sh stratospheric polar vortex the resulting perturbation to gravity wave gw filtering causes anomalous sh mesospheric eastward gw forcing and polar upwelling and cooling in addition constructive inference of enso and quasi biennial oscillation qbo could lead to st

environmental reconstruction and dating of shizitan 29 shanxi province an early microblade site in north china global cooling during the last glacial maximum lgm posed significant challenges to peoples living in northern eurasia using micromorphology pollen and non pollen palynomorphs npp and faunal analyses this study reconstructs the local paleoenvironmental contexts of repeated ephemeral occupations at shizitan 29 in shanxi province north china across the lgm from ca 28 to 18 ka cal bp followed by a gap until a final occupation ca 13 5 ka cal bp among the significant finds at shizitan 29 are remains of 285 hearths and a rich lithic assemblage that contains the earliest radiocarbon dated evidence for microblades in china appearing first in layer 7 the environmental data show that the low mountains and tributary river valleys of the yellow river in the loess plateau provided abundant sources of water and food in spite of environmental fluctuations microblade producing groups repeatedly visiting this locality survived severe climate change by making use of fire selective herbivore hunting processing plant foods with grinding stones and symbolic ornamentation such as ostrich shell beads npp data also indicate the potential presence of flax and other fiber processing the shizitan 29 data demonstrate how humans adapted to challenging local conditions throughout the lgm allowing them to stay within this northerly region without migrating to warmer southern latitudes

the application of geometric morphometric shape analysis to middle paleolithic bone retouchers from the altai mountains russia abstract here we apply geometric morphometric shape analysis to middle paleolithic bone retouchers from chagyrskaya cave in the altai mountains of southern siberia the cave contains evidence of the easternmost manifestation of the micoquian industry associated with neanderthals at end of mis4 and the beginning of mis3 taphonomic and scar pattern analyses were performed first on random samples exhibiting appropriate characteristics several retouchers produced on intentionally modified blanks were identified in our sample suggesting that some of the chagyrskaya cave bone retouchers can be described as formal tools all retouchers from chagyrskaya cave exhibit a similar general morphology the most variable group is comprised of complete retouchers without blank modifications retouchers exhibiting minor damage affect the general pattern of variability and it is not possible to identify them only by means of geometric morphometric shape analysis complete retouchers with blank modifications fall within the range of variability of complete retouchers without blank modification suggesting intentional shaping of blanks to conform to a standard template the range of variability of the bone retouchers does not differ significantly from that of the most highly modified lithic artifacts at chagyrskaya plano convex bifaces which may indicate intentional shape control for such artifacts geometric morphometric analysis indicates that the anatomical origin of bone blanks does not significantly influence the retouchers shape which may point to strict blank selection and at the same time intentional modification our results raise questions regarding the integration of retouchers into a complex multidimensional chaine operatoire as well as the nature of neanderthal cognitive abilities geometric morphometric shape analysis represents a major step forward in the study of prehistoric retouchers

food or fibercraft grinding stones and aboriginal use of triodia grass spinifex plant tissue and wooden objects are rare in the australian archaeological record but distinctive stone tools such as grinding stones and ground edge hatchets are relatively common and they provide strong indirect evidence for plant food processing and woodworking respectively ethnohistorical references to the aboriginal use of stone tools for technologies related to fibercraft basketry hafting adhesives and fixative sealants with gum wax and resin are also rare but all these tasks were probably more common than records indicate here we consider ethnohistorical evidence for stones in fibercraft and the processing of triodia grass spinifex as a case study we compare functional traces on experimental stones with traces on a museum specimen cmaa 1926 591 which was collected ethnohistorically and reportedly used for grinding spinifex leaves residues and other traces on the museum specimen are consistent with both fiber processing and seed grinding we suggest that it may be difficult for usewear and residue analysis to determine if grinding stones were used to target triodia spinifex for fiber food or another particular plant product further experimental research is needed to refine criteria for identifying archaeological fiber processing tools however we propose that the combination of traces previously interpreted as seed processing on bedrock grinding patches and portable grinding stones may also indicate the processing of triodia spinifex for fiber

climatological effects of orography and land sea heating contrasts on the gravity wave driven circulation of the mesosphere abstract on the basis of permanent january simulations performed with an idealized general circulation model for the troposphere and middle atmosphere the sensibility of the general circulation to orographic and thermal forcing of large scale stationary waves is assessed gravity waves are parameterized following lindzen s saturation theory up to the stratopause present model results coincide with earlier estimates confirming that the boreal winter zonal mean climate does crucially depend on the combined action of orography and land sea heating contrasts since in turn the propagation and breakdown of internal gravity waves is strongly modulated by the background horizontal winds the mesospheric response to stationary wave forcing turns out be substantial as well it is found that in the climatological zonal mean a warmer polar night stratosphere is accompanied by lower temperatures in the mesosphere up to about 80 km the temperature signal induced by stationary wave forcing changes sign again in

geochemistry petrology and ages of the lunar meteorites kalahari 008 and 009 new constraints on early lunar evolution abstract kalahari 008 and 009 are two lunar meteorites that were found close to each other in botswana kalahari 008 is a typical lunar anorthositic breccia kalahari 009 a monomict breccia with basaltic composition and mineralogy based on minor and trace elements kalahari 009 is classified as vlt very low ti mare basalt with extremely low contents of incompatible elements including the ree the lu hf data define an age of 4286 95 ma indicating that kalahari 009 is one of the oldest known basalt samples from the moon it provides evidence for lunar basalt volcanism prior to 4 1 ga pre nectarian and may represent the first sample from a cryptomare the very radiogenic initial 176hf 177hf ehf 12 9 4 6 the low ree th and ti concentrations indicate that kalahari 009 formed from re melting of mantle material that had undergone strong incompatible trace element depletion early in lunar history this unusually depleted composition points toward a hitherto unsampled basalt source region for the lunar interior that may represent a new depleted endmember source for low ti mare basalt volcanism apparently the moon became chemically very heterogeneous at an early stage in its history and different cumulate sources are responsible for the diverse mare basalt types evidence that kalahari 008 and 009 may be paired includes the similar fayalite content of their olivine the identical initial hf isotope composition the exceptionally low exposure ages of both rocks and the fact that they were found close to each other since cryptomaria are covered by highland ejecta it is possible that these rocks are from the boundary area where basalt deposits are covered by highland ejecta the concentrations of cosmogenic radionuclides and trapped noble gases are unusually low in both rocks although kalahari 008 contains slightly higher concentrations a likely reason for this difference is that kalahari 008 is a polymict breccia containing a briefly exposed regolith while kalahari 009 is a monomict brecciated rock that may never have been at the surface of the moon altogether the compositions of kalahari 008 and 009 permit new insight into early lunar evolution as both meteorites sample lunar reservoirs hitherto unsampled by spacecraft missions the very low th and ree content of kalahari 009 as well as the depletion in sm and the lack of a kreep like signature in kalahari 008 point to a possible source far from the influence of the procellarum kreep terrane possibly the lunar farside

the still bay points of blombos cave south africa we present the results of a technological and morphometric analysis of all the still bay points n 371 recovered from the 1993 to 2004 excavations at blombos cave we have been able to reconstruct the manufacturing sequence of the bifacial points from initial shaping by direct internal percussion to finished morphology by direct marginal percussion identifications of impact fractures and manufacturing breaks are based on comparisons with experimental and archaeological bifacial points of verified function i e paleoindian points from bison kill sites replicates of solutrean points mounted as spear heads or arrowheads and shot into adult cattle and experimental replication on local raw materials our analysis shows that a only a minority of the points are finished forms and that a large number of pieces are production failures a situation known at bifacial point production sites of later ages b morphometric and impact scar analyses should take into account this process and distinguish finished points from preforms and unfinished points c there were at least three different kinds of raw material sources and that there is a marked increase in the frequencies of silcrete with respect to the m2 and m3 phases at blombos d three kinds of evidence prove that some of the points were hafted axially and used as spear tips e production of bifacial points was a primary activity at the site but the hypothesis of intergroup exchange of still bay points cannot be sustained on the basis of present evidence and f the still bay phase appears to initiate a trend to relatively rapid changes in specialized hunting weaponry and that this innovation is congruent with other innovations such as bone tools shell beads and engraved ochre of the m1 and m2 phases at blombos

isotope systematics and shock wave metamorphism ii u pb and rb sr in naturally shocked rocks the haughton impact structure canada minerals and whole rocks from crystalline fragments collected in the allochthonous polymict breccia of the 23 ma old haughton impact crater on devon island arctic canada were analysed for u pb k and rb sr in order to constrain degrees of shock wave induced perturbations in these systems the results show that shock wave metamorphism at 50 gpa with onset of total melting does not significantly affect the u pb chronometers in monazite and zircon monazite preserved its age of crystallization during high grade metamorphism at 1928 2 2 1 2 0 ma 2 errors as dated by the upper intercept of 2 9 discordant monazites the same analyses yield a lower intercept age of 277 5 35 1 35 0 ma in the concordia diagram demonstrating that discordancy is not a direct effect of shock wave metamorphism but a product of time integrated pb diffusion prior to the impact event which occurred 23 ma ago this constrains maximal shock induced pb loss to less than 3 including possible alteration related pb diffusion from the shock damaged grains in 1903 1 1 4 1 1 ma old monazite from an unshocked reference gneiss recent pb loss also reaches 3 corroborating the occurrence of weak alteration related upb fractionation the data substantiate that u pb discordancy patterns are not a reliable chronometer to date impact events small rock fragments and a coherent block of shock stage i to iii vi consist of heterogeneous unequilibrated rb sr sub systems on the 10 m scale with drastically varying isr shock related rbsr fractionation is very limited and in the large block stage iii three biotite fractions yield an rb sr isochron age of 1791 34 ma 2 which is undistinguishable from the 1814 8 ma age of biotite in the unshocked basement gneiss in contrast to this m3 sized fragment rb sr systematics in a fist size sample of shock stage iii do not yield any reliable age information due to small scale 1 cm3 isotopic disequilibrium it appears that such small scale disequilibrium is essentially due to a take up of radiogenic 87sr in feldspar glass from biotite during shock wave passage this prevents dating of the impact events by the rb sr internal isochron method and it can be concluded that total rock melting is the first condition necessary to reset the rb sr chronometer in shocked crystalline rocks

finding resolution for the howiesons poort through the microscope micro residue analysis of segments from sibudu cave south africa in this paper i present the results of a micro residue analysis of stone segments the type fossils of the howiesons poort technocomplex in south africa with an age of more than 60 ka at sibudu cave kwazulu natal fifty three segments were systematically analysed and 1826 organic micro residue occurrences were documented on the sample the distribution patterns of micro residues and other use traces are interpreted in terms of hafting and function it is shown that most of the tools were indeed hafted and most were probably used as inserts for hunting weapons there is evidence for differences and changes over time in haft materials and hafting configurations of the segments the study demonstrates how functional studies could improve our understanding of change and variability in human behaviour during the middle stone age a period that used to be portrayed as static or slow changing

the significance of shuidonggou locality 12 to studies of hunter gatherer adaptive strategies in north china during the late pleistocene the effect of rapid climate change during the late upper paleolithic on hunter gatherers is attested by a variety of signals in the archaeological record one of these the spread of the microblade technology in north china shows a particularly close relationship with climate change the appearance of microblades and functionally related bone and ground stone technology at sdg12 is particularly revealing of this late pleistocene adaptive diversification in north china sdg12 and other records suggest that microblade technology flourished in harsh environments that demanded high residential mobility that in addition to their use in hunting weaponry microblades were used in manufacturing the sophisticated cold weather clothing required for winter mobility is shown by the presence of bone needles and a bone knife handle slotted to accept microblades the sdg12 fauna and ground stone indicate an attendant shift from a more large game dominated to a more plant and small game dominated diet that included net hunting and demanded a variety of production tasks that included net making spinning and extensive stone boiling to maximize nutrient returns and as a step in manufacturing we suspect these changes are the root cause of subsequent changes in social structure

context matters ar ar results from in and around the manicouagan impact structure canada implications for martian meteorite chronology abstract as an analog for interpretations of the ages of martian shergottite meteorites we have conducted an argon isotopic study of plagioclase feldspars exhibiting varying levels of shock from in and around the manicouagan impact structure canada plagioclase from the impact melt sheet at manicouagan yields an age of 215 40 0 16 ma which indicates the time of impact plagioclase from a clast within melt bearing breccias of the melt sheet and a hornfels adjacent to the melt sheet yield ages of 216 3 ma and 218 7 ma respectively which are interpreted to have been reset by contact metamorphism from the impact melt country rocks that were unaffected by the impact gives 849 ma ages consistent with the known grenvillian target rock history maskelynite amorphous plagioclase which has been transformed in the solid state yields an age of 567 6 ma this age is geologically meaningless because it is not consistent with the target age the impact age or regional metamorphic ages at manicouagan our results show that maskelynite argon ages are not meaningful and that context is critical for proper interpretation of impact affected argon ages

a stratigraphical basis for the last glacial maximum lgm abstract the last glacial maximum lgm is widely used to refer to the episode when global ice volume last reached its maximum and associated sea levels were at their lowest however the boundaries of the interval are ill defined and the term and acronym have no formal stratigraphical basis this is despite a previous proposal to define it as a chronozone in the marine records on the basis of oxygen isotopes and sea levels spanning the interval 23 19 or 24 18 ka and centred on 21 ka in terrestrial records the lgm is poorly represented since many sequences show a diachronous response to global climate changes during the last glacial cycle for example glaciers and ice sheets reached their maximum extents at widely differing times in different places in fact most terrestrial records display spatial variation in response to global climate fluctuations and changes recorded on land are often diachronous asynchronous or both leading to difficulties in global correlation however variations in the global hydrological system during glacial cycles are recorded by atmospheric dust flux and this provides a signal of terrestrial changes whilst regional dust accumulation is recorded in loess deposits global dust flux is best recorded in high resolution polar ice core records providing an opportunity to define the lgm on land and establish a clear stratigraphical basis for its definition on this basis one option is to define the global lgm as an event between the top end of greenland interstadial 3 and the base onset of greenland interstadial 2 spanning the interval 27 540 23 340 ka greenland stadial 3 this corresponds closely to the peak dust concentration in both the greenland and antarctic ice cores and to records of the global sea level minima this suggests that this definition includes not just the coldest and driest part of the last glacial cycle but also the peak in global ice volume the later part of the lgm event is marked by heinrich event 2 which reflects the onset of the collapse of the laurentide at c 24 ka together with other ice sheets in the north atlantic region a longer and later span for the lgm may be desirable although defining this in chronostratigraphical terms is problematic whichever formal definition is chosen this requires the contribution of the wider quaternary community

loss of radiogenic argon from shocked granitic clasts in suevite deposits from the ries crater five granitic clasts from the otting and aumuhle quarries in the suevite ejecta deposits beyond the rim of the ries germany impact crater have been characterized as to modal composition degree of shock and loss of radiogenic argon the shock pressures experienced by this selected suite of samples range from 60 gpa and the samples have been modestly shocked to heavily shocked or even melted ages for these samples were determined by the 39ar40ar technique the least shocked specimen 10 15 gpa shows very little loss of radiogenic ar relative to the approximately 320 my age of the variscan basement at the ries all other samples 28 gpa 42 gpa 52 gpa and an impact melt suggest complete to nearly complete loss of radiogenic ar at the time of the 15 my old impact event most of the radiogenic ar in these granitic samples is contained in feldspar with a lesser amount in biotite diffusive loss of ar occurs relatively easily from these highly disordered feldspars the essentially complete loss of radiogenic ar from 4 of the 5 samples is in large part ascribed to thermal activation during the cooling history of the suevite rather than during initial passage of the shock wave these data are consistent with the conclusion from previous paleomagnetic studies that the suevite was deposited at temperatures above 500 c the fact that staudacheret al 1982 found almost no loss of radiogenic ar in a wide variety of ries samples is ascribed to two causes a most of their samples were shocked to 15 gpa and were collected in drill cores from the modestly shocked crater bottom which was not as hot as the suevite and b their observations were primarily made on hornblende and biotite separates that are more resistant to shock effects and to diffusive loss of ar compared to shocked feldspars loss of argon from our suevite samples likely occurred in a hot post impact ejecta layer from data presented here we estimate that 50 of the material composing the hot ries ejecta should show at least partially reset k ar ages such materials compose no more than 5 of the total displaced crater volume

the mousterian bone retouchers of noisetier cave experimentation and identification of marks retouchers are fragments of bone used during the paleolithic to strike stone flakes in order to transform them into retouched tools our experiments show that the mark produced on retouchers differs depending on whether they were used to strike flint or quartzite our results suggest that numerous pits most often with an ovoid form characterize the retouching of quartzite flakes most of the scores produced with this material have a sinuous morphology with rough interior faces the areas with superposed traces have a pitted appearance on the other hand the retouching of flint flakes produces pits that are most often triangular in form most of the scores have a rectilinear morphology with smooth interior faces and their superposition results in the formation of hatch marks there is also a relationship between the characteristics of the mark and the relative state of freshness of the retouchers the validity of the criteria identified was confirmed by a blind test these diagnostic criteria were applied to archaeological retouchers from the mousterian site of noisetier cave the results obtained improve our knowledge of the technical behaviors of neanderthals and allow us to address questions concerning their techno economic implications

late glacial bifacial microblade core technologies in hokkaido an implication of human adaptation along the northern pacific rim abstract the wedge shaped microblade core technology found along the northern pacific rim has been regarded as a trait of hunter gatherer adaptation during the late glacial and initial holocene having recognized variable microblade core reduction methods among the technocomplexes in hokkaido by employing an optimization model in lithic technology the present paper addresses the question of what role bifacial microblade core technologies played in foraging through a comparative analysis of utility cost of transportation and failure rates between the larger sakkotsu and smaller oshorokko bifacial microblade core technologies in the late glacial hokkaido results suggest that as opposed to the larger bifacial microblade core technology the smaller bifacial microblade core technology was more effective for exploring unpredictable environment across the northern pacific rim

when neanderthals used cave bear ursus spelaeus remains bone retouchers from unit 5 of scladina cave belgium abstract evidence of neanderthals using bear remains as retouchers is rare in the sedimentary unit 5 of scladina cave belgium weichselian early glacial mis 5d to 5b twenty six bone retouchers have been discovered among these six have been made from cave bear bones four from a femur and two from two tibiae the presence of lithic splinters still embedded in grooves can be convincingly associated with their function as knapping tools particularly interesting are six bone fragments including four fragments used as retouchers and two unused splinters which have been refitted together to reconstitute an almost complete cave bear femur diaphysis these specimens present modifications in the form of cut marks scraping marks impact notches and typical fractures of percussions on green fresh bone sometimes overlapping each other that allow for a complete understanding of the operational sequence in the production of bone retouchers at this site the identification of a sophisticated operational sequence where each action succeeds another in the production of a bone tool is a major argument in favor of predetermination that guided the neanderthal actions and is similar to that described for stone tool chaine operatoire

30 000 year old wild flax fibers a unique finding of wild flax fibers from a series of upper paleolithic layers at dzudzuana cave located in the foothills of the caucasus georgia indicates that prehistoric hunter gatherers were making cords for hafting stone tools weaving baskets or sewing garments radiocarbon dates demonstrate that the cave was inhabited intermittently during several periods dated to 32 to 26 thousand years before the present kyr b p 23 to 19 kyr b p and 13 to 11 kyr b p spun dyed and knotted flax fibers are common apparently climatic fluctuations recorded in the cave s deposits did not affect the growth of the plants because a certain level of humidity was sustained

shocked meteorites argon 40 argon 39 evidence for multiple impacts to contribute to the understanding of the impact history of asteroids we performed a high resolution 40ar 39ar study of ten moderately to highly shocked chondrites which we selected according to the shock classification given by stoffler et al 1991 two recent shocked chondrite falls and two highly shocked eucrites completed our sample suite when possible we separated impact melt from host rock for separate analysis in total we studied 28 samples from 14 meteorites in some cases atmospheric ar that we associate with terrestrial weathering was identified and corrected for the ages we obtained range between 100 ma and 4 1 ga and are clearly distinct from primordial ages that correspond to solar system formation we reproduced the previously reported cluster of l chondrite ages 500 ma the most prominent result of our study is that in the case of chondrites melts generally are older than host rocks or melt embedded unmolten rocks to solve this apparent paradox we propose that the melt forming event which was the most severe shock episode in the history of these meteorites has not been the only occasion affecting their k ar systems at least one later impact metamorphism must have occured the response of the k ar clock to this second event was more severe in the host rock than in the previously in the first event generated melt veins and pockets because of different ar retention rates hence impact metamorphism on meteorite parent bodies indeed was a multistage process extending in time over billions of years

on the siting of gases shock emplaced from internal cavities in basalt abstract noble gases were extracted by stepped combustion and crushing from basalts which contained gas filled cavities of controlled sizes prior to shock at 40 gpa analysis of fractions enriched and depleted in shock glass from a single sample gave a factor of 2 higher gas abundances in the glass rich separate release patterns were nearly identical suggesting similar siting in glass in both fractions crushing of a sample released 45 of implanted noble gases but only 17 of n 2 indicating that most or all of the noble gas was trapped in vesicles analysis by sem eds confirmed the presence of vesicles in glassy areas with an average diameter of 10 m samples with relatively large pre shock cavities were found to consist of up to 70 80 glass locally and generally exhibit greater local shock effects than solid and densely packed paniculate targets at the same shock pressure though the latter give higher gas emplacement efficiencies the petrographic results indicate that in situ production of glassy pockets grossly similar to those in the shergottite eeta 79001 is possible from shock reverberations in the vicinity of a vug however the siting of the gases points to a more complex scenario in which spb gas and melt material were probably injected into eeta 79001

the paleolithic site of longwangchan in the middle yellow river china chronology paleoenvironment and implications the longwangchan paleolithic site situated on the yellow river terraces in the hukou area shaanxi province china was found in 2003e2004 and two areas localities 1 and 2 of the site were excavated in 2005e2008 abundant stone artifacts including microliths a grinding stone fragment and a shovel with some animal bones and shells were recovered from locality 1 in this study the cultural deposits from locality 1 were dated using radiocarbon and optical dating techniques and the sediment properties of the deposits were analyzed the results show that the age of the deposits ranges from 29 to 21 ka and most of them were deposited between 25 ka and 29 ka this indicates that corresponds to late marine isotope stage mis 3 and early mis 2 during the human occupation period the climate in this area became colder and drier sediments from beds where the grinding slab and the shovel were found were dated to w25 ka which is the oldest among the grinding stones found in china the microliths and the grinding stone are important evidence for an incipient socio economic process that eventually led to the regional transition from hunting foraging to farming

neanderthal and animal karstic occupations from southern belgium and south eastern france regional or common features abstract karstic systems have preserved abundant archaeological records with well represented faunal remains due to their sedimentological and topographical features these particular localities were intensely exploited and occupied by neanderthal groups we focus here on middle palaeolithic settlements from the last glacial period mis 5d 3 which is characterized by marked climatic variability with colder episodes alternating with more temperate periods the ardeche region in south eastern france and the meuse basin in belgium have recently been the focus of regional studies combining archaeological geological and chronological data in order to bring to light human land use and subsistence strategies these two areas comprise multiple rock shelters and caves with neanderthal occupations dating from mis 5d to 3 as well as the obvious traces of occupation by neanderthals most sites provide evidence of carnivore occupations e g cave bears cave hyenas or wolves each of these habitation sites presents a specific topography and type of occupation and most of them reveal behavioural homogeneity within their sequences by comparing data from faunal accumulations in these two related areas separated by a distance of about one thousand kilometres we attempt to gain a better understanding of the driving forces behind neanderthal and animal occupations of karstic networks do regional land use patterns exist in different european karstic localities or can we perceive common features related to the geography and topography of the sites

millennial scale iceberg discharges in the irminger basin during the last glacial period relationship with the heinrich events and environmental settings high resolution records of coarse lithic content and oxygen isotope have been obtained in a piston core from the irminger basin the last glacial period is characterized by numerous periods of increased iceberg discharges originating partly from iceland and corresponding to millennial scale instabilities of the coastal ice sheets and ice shelves in the nordic area a comparison with midlatitude sediment cores shows that ice rafted material corresponding to the heinrich events was deposited synchronously from 40 to 60 n there are thus two oscillating systems every 5 10 kyr massive iceberg armadas are released from large continental ice caps whereas more frequent instabilities of the coastal ice sheets in the high latitude regions occur every 1 2 3 8 kyr at the time of the heinrich events the synchroneity of the response from all the northern hemisphere ice sheets attests the existence of strong interactions between the two systems

pleistocene sea level fluctuations and human evolution on the southern coastal plain of south africa abstract humans evolved in africa but where and how remain unclear here it is proposed that the southern coastal plain scp of south africa may have served as a geographical point of origin through periodic expansion and contraction isolation in response to glacial interglacial changes in sea level and climate during pleistocene interglacial highstands when sea level was above 75 m human populations were isolated for periods of 360 3400 25 yr generations on the scp by the rugged mountains of the cape fold belt climate and vegetation barriers the scp expands five fold as sea level falls from 75 to 120 m during glacial maxima to form a continuous unobstructed coastal plain accessible to the interior an expanded and wet glacial scp may have served as a refuge to humans and large migratory herds and resulted in the mixing of previously isolated groups the expansive glacial scp habitat abruptly contracts by as much as one third in 300 yr during the rapid rise in sea level associated with glacial terminations rapid flooding may have increased population density and competition on the scp to select for humans who expanded their diet to include marine resources or hunted large animals successful adaptations developed on an isolated scp are predicted to widely disperse during glacial terminations when the scp rapidly contracts or during the initial opening of the scp in the transition to glacial maxima the hypothesis that periodic expansion and contraction of the scp as well as the coastal plain of north africa contributed to the stepwise origin of our species over the last 800 thousand years kyr is evaluated by comparing the archeological dna and sea level records these records generally support the hypothesis but more complete and well dated records are required to resolve the extent to which sea level fluctuations influenced the complex history of human evolution

ma anshan cave and the origin of bone tool technology in china abstract here we present the results of a techno functional analysis of 17 bone tools recovered from strata 6 5 and 3 of the palaeolithic site of ma anshan cave guizhou province southern china stratum 6 dated to c 35 cal kyr bp has yielded three sharp awls from stratum 5 dated to c 34 cal kyr bp come six probable spear points awls and a cutting tool separated from these layers by a sterile horizon stratum 3 dated 23 cal kyr bp to 18 cal kyr bp has yielded barbed points of two types bone tools were shaped by scraping grinding and in strata 5 and 3 finished by polishing ma anshan cave records the oldest formal bone tools from china and amongst the oldest known evidence of indisputable barbed point manufacture outside africa change in the hunting toolkit between strata 5 and 3 may indicate a shift in prey preference from medium to small size mammals and fish which needs to be verified by supplementary analyses the significance of this evidence is discussed in the context of what is known about the origin of bone tool technology in africa and eurasia

petrology geochemistry and age of low ti mare basalt meteorite northeast africa 003 a a possible member of the apollo 15 mare basaltic suite abstract northeast africa 003 nea 003 is a lunar meteorite found as a two paired stones 6 and 118 g in libya 2000 and 2001 the main portion 75 vol of the 118 g meteorite used for this study nea 003 a consists of mare basalt and a smaller adjacent portion 25 vol is a basaltic breccia nea 003 b nea 003 a has a coarse grained magmatic texture consisting mainly of olivine pyroxene and plagioclase the late stage mineral association is composed mainly of elongated plagioclase ilmenite troilite fayalite si k rich glass apatite and a rare sio2 phase other accessory minerals include ulvospinel chromite and trace fe ni metal olivine and pyroxene contain shock induced fractures and plagioclase is completely converted into maskelynite the fe mn values of the whole rock olivines and pyroxenes and the bulk rock oxygen isotopic composition provide evidence for the lunar origin of nea 003 a meteorite this is further supported by the presence of fe ni metal and the anhydrous mineral association nea 003 a is geochemically and petrographically distinct from previously described mare basalt meteorites and is not paired with any of them the petrography and major element composition of nea 003 a is similar to the composition of low ti olivine mare basalts from apollo 12 and olivine normative basalts from apollo 15 the nea 003 a meteorite shows obvious geochemical similarities in trace elements contents with apollo 15 olivine normative basalts and could represent a yet unknown geochemically primitive member of the olivine normative basalt series the meteorite is depleted in rare earth elements ree and incompatible trace elements indicating a primitive character of the parental magma the bulk rock chemical composition demonstrates that the parent melt of nea 003 a was not contaminated with kreep components as a result of magma mixing or assimilation processes results of crystallization modelling and low minimum cooling rate estimates 0 07 c h suggest that the parent melt of nea 003 a crystallized in the lower part of a lava flow containing cumulate olivine 10 and was probably derived from more primitive picritic magma by fractional crystallization processes sm nd dating yields an age of 3 09 0 06 ga which corresponds to the period of lower eratosthenian lunar volcanic activity and the near chondritic end value of 0 4 0 3 indicates that the meteorite could be derived from a slightly enriched mantle source similar to the apollo 15 green glasses ar ar step release results are inconsistent with sm nd ages suggesting that nea 003 a was exposed to one or more impact events the most extensive event took place at 1 8 ga and the shock intensity was likely between 28 and 45 gpa the absence of solar ar suggests that nea 003 a has not been directly exposed at the lunar surface but the cosmic ray exposure age of 209 6 ma suggests that nea 003 a resided in the upper regolith for part of its history

variability of diffusion of argon in albite pyroxene and olivine in shocked and unshocked samples abstract we analyzed the argon diffusion parameters of albite and pyroxene as a function of shock as well as an olivine of unknown shock pressure in albite shock pressures of 30 60 gpa all have an equal effect on the diffusion parameters lowering the activation energy e from 45 to 25 kcal mol and the log d0 a2 from 4 to 1 s 1 in a mixture of low ca and high ca pyroxene similar shock pressures also have an equal effect lowering the e from 130 to 80 kcal mol and the log d0 a2 from 14 to 7 s 1 however given that some shocked and unshocked pyroxene splits have similar release patterns making a clear distinction between the two is difficult additionally splits of pure unshocked high ca pyroxene have an e of 100 kcal mol and a log d0 a2 of 10 s 1 intermediate to the values of mixed pyroxene when shocked and unshocked the olivine fa18 has an e of 45 kcal mol and a log d0 a2 of 1 s 1 somewhat similar to that of feldspar these results will be useful in interpreting complex argon release patterns from shocked multi mineral samples too fine grained for easy mineral separation such as chondrites

a stratigraphic framework for abrupt climatic changes during the last glacial period based on three synchronized greenland ice core records refining and extending the intimate event stratigraphy due to their outstanding resolution and well constrained chronologies greenland ice core records provide a master record of past climatic changes throughout the last interglacial glacial cycle in the north atlantic region as part of the intimate integration of ice core marine and terrestrial records project protocols have been proposed to ensure consistent and robust correlation between different records of past climate a key element of these protocols has been the formal definition and ordinal numbering of the sequence of greenland stadials gs and greenland interstadials gi within the most recent glacial period the gs and gi periods are the greenland expressions of the characteristic dansgaard oeschger events that represent cold and warm phases of the north atlantic region respectively we present here a more detailed and extended gs gi template for the whole of the last glacial period it is based on a synchronization of the ngrip grip and gisp2 ice core records that allows the parallel analysis of all three records on a common time scale the boundaries of the gs and gi periods are defined based on a combination of stable oxygen isotope ratios of the ice 18o reflecting mainly local temperature and calcium ion concentrations reflecting mainly atmospheric dust loading measured in the ice the data not only resolve the well known sequence of dansgaard oeschger events that were first defined and numbered in the ice core records more than two decades ago but also better resolve a number of short lived climatic oscillations some defined here for the first time using this revised scheme we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the last glacial period that are represented in the greenland ice records the final product constitutes an extended and better resolved greenland stratotype sequence against which other proxy records can be compared and correlated it also provides a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations

on the significance of crater ages new ages for dellen sweden and araguainha brazil samples of a few grams in weight from the impact melt at the dellen crater sweden and the araguainha dome brazil were analyzed by rb sr and sm nd techniques for dellen pure labradorite orthopyroxene and glass separates from a clast free impact melt rock with holohyaline ground mass yield an internal rb sr isochron with 89 0 2 7 ma isr 0 83571 0 00007 2 compared to ar ar plateau ages of 102 3 2 ma and 109 6 2 0 ma published for total melt rocks various whole rock values not plotting on this rb sr isochron indicate primary variations in 87sr86sr over the melt sheet the age of the araguainha dome brazil is bracketed by the rb sr model age of 243 19 ma isr 0 7226 0 0005 for altered cordierite in the impact melt and by the internal rb sr isochron age of 449 9 ma isr 0 7140 0 0007 for an uplifted granite shock stage ib in melt rocks from both impact structures 143nd144nd was not homogenized during total rock melting sm nd data either scatter around the primary isochron araguainha or point to a partial resetting dellen this data array may be caused by tiny refractory ree rich inclusions in the main mineral phases which dominate the sm nd system of the impact melt rocks the significant difference between the new isochron age for dellen and ar ar ages show that the data base for analysis of periodicity in cratering record most probably lack precision and accuracy

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

what happens around a fire faunal processing sequences and spatial distribution at qesem cave 300 ka israel abstract the technological innovation involving the controlled use of fire represents a decisive change in human subsistence hearths and the spatial distribution patterns associated with them constitute a valuable element in deepening our knowledge on human behaviour and its evolution studies focused on hearths and on the use of fire in general are diverse and carried out through different perspectives thus hearths are studied for their meaning in terms of diet caloric and light capacity and spatial organisation as well as for their role as communication and socialization focal points the site of qesem cave israel shows evidence of the controlled use of fire as early as 400 ka judging by the burned bones from the lowest units of the stratigraphic sequence a particular superimposed central hearth that was repeatedly used as a focus for human activities ca 300 ka is the topic of this study this succession of hearths at the same location in the cave yields dense faunal and lithic remains as well as evidence for spatial differentiation between areas here we present faunal taphonomical data from this specific archaeological context which includes not only the hearth area approximately 4 m2 but also the surrounding areas approximately 11 m2 the most common prey species is the mesopotamian fallow deer dama cf mesopotamica which displays a wide age range and a biased anatomical profile including mainly marrow rich bones such as long limb bones these characteristics especially those regarding the relative abundance of infantile and young fallow deer lead us to propose that social hunting techniques were practised following a seasonal regime this paper provides data on human subsistence behaviour during the formation of the hearth and the archaeological unit around it comparing the two from a taphonomical perspective elements such as size length of bone fragments and intensity of burning are spatially plotted to show differential space division all these data are considered in the reconstruction of subsistence strategies and hominin behaviour in the acheulo yabrudian cultural complex in the levant

variability in the middle stone age lithic sequence 115 000 60 000 years ago at klasies river south africa abstract stratified samples of artefacts from the late pleistocene deposit at the klasies river main site covering some 60 000 years have been studied variability in the artefact sequence has been documented in the technologies of artefact production in addition to conventional typological analysis particular emphasis has been given to the recognition of the reduction sequences used in producing the pre formed blanks that are a feature of the middle stone age the results show that the variability is due to changes between the dominant blade and or point technological conventions traditions through time technological study supports and gives meaning to the recognition of distinct sub stages msa i klasies river msa ii mossel bay howiesons poort and a post howiesons poort at main site these sub stages are more than convenient site specific organizational entities they delineate separate technological conventions that may have relevance on a sub continental scale

cratering history and lunar chronology the moon is exceptional and important because it is the only planetary body besides the earth for which we have both a detailed stratigraphic history and datable rock samples that can be related to specific geomorphologic units fig 5 1 the moon has preserved much of its magmatic and impact record of at least the last 4 billion years while its endogenic history is of great interest for the fundamentals of planetary interiors and surfaces the moon has become a calibration plate for the cratering record of the earth moon system and by extrapolation of the entire inner solar system if one assumes a heliocentric origin for impactor populations these populations range from asteroids through long and short period comets to interplanetary dust and cover a size range from hundreds of kilometers to micrometers figure 5 1 telescopic view of the nearside of the earth s moon with landing sites of the apollo and luna missions this chapter reviews the presently available data sets in support of this paradigmatic assumption as follows 1 the phenomenology of lunar impact craters 2 the terrestrial record of the impact cratering process and the interpretation of terrestrial impactites as far as this ground truth is relevant for the interpretation of lunar impact craters and datable lunar impact breccias and melt rocks 3 the theory and numerical simulation of the cratering process and the characteristics of the earth moon crossing population of impactors asteroids and comets 4 the principles of relative age dating of lunar surface units and the general lunar stratigraphy 5 the stratigraphic significance and ages of lunar samples impactites and basalts and based on this data set the absolute ages of lunar surface units 6 the cratering rate of the moon as a function of time and 7 the time calibration of this cratering rate based on the

innovation in bone technology and artefact types in the late upper palaeolithic of china insights from shuidonggou locality 12 abstract information on palaeolithic bone technology from china is sparse here we present the results of a techno functional analysis of a bone tool assemblage recovered from shuidonggou locality 12 sdg12 layer 11 northern china dated to c 12 11 cal ka bp six bone tool artefact types are identified wedges awls spear points a knife handle a possible sewing implement and a notched carpal two other artefacts could not be attributed to a specific type the artefacts are made of procapra przewalsikii lepus sp sus sp equus przewalskii and unidentifiable bone fragments from medium large size mammals at least three methods are used to extract blanks percussion of altered limb bones longitudinal splitting of sus sp canine and large rib and probably the groove and splinter technique grinding and scraping are the dominant shaping techniques together with grooving notching polishing drilling flaking and retouching tool type variability and function fit the hypothesis according to which the sdg12 and similar sites would be residential camps in which hunter gatherers produced artefacts enabling them to cope with cold environmental conditions our results however indicate that not all bone tools match the expectations associated with a serial specialist production expedient wedges and awls may have been produced by any member of the group and whenever the need arose the sdg12 bone tool assemblage provides a significant contribution to our knowledge about hunter gatherer adaptations to the tardiglacial environments of northern china

late persistence of the acheulian in southern britain in an mis 8 interstadial evidence from harnham wiltshire this paper presents evidence of the discovery of a new middle pleistocene site in central southern england with undisturbed evidence of hominin occupation well dated to an interstadial towards the end of marine isotope stage 8 c 250 000 bp the site consists of a preserved remnant of a river terrace and its alluvial floodplain overlain by chalk rich bankside deposits all abutting a chalk bedrock riverbank it preserves an area of occupation with activity focused on the riverbank complemented by occasional activity on a palaeo landsurface developed on the surface of the alluvial floodplain lithic technology at the site consists almost entirely of handaxe manufacture allowing attribution to an acheulian industrial tradition mammalian and other palaeo environmental remains are present and associated with the occupation horizons including large mammal bones showing signs of hominin interference dating was based on osl determinations on the sediments and amino acid racemisation of molluscan remains supported by biostratigraphic indications besides being a rare instance of an undisturbed palaeolithic palaeo landscape covering several hectares the site contributes to wider quaternary research concerns over the ability of middle pleistocene hominins to tolerate colder climatic episodes in higher latitudes and over settlement history and changing lithic industrial traditions of northwest europe in relation to climate change and british peninsularity it is suggested that the harnham evidence may represent an insular population that had persisted in southern britain since mis 10 9 which became locally extinct during the glacial maximum 8 2 marking the end of mis 8

new ages for the upper palaeolithic site of xibaimaying in the nihewan basin northern china implications for small tool and microblade industries in north east asia during marine isotope stages 2 and 3 it has been suggested that the small tool and microblade upper palaeolithic industries coexisted in the nihewan basin of northern china for about 8 14 000 years during marine isotope stage mis 2 this inference was based on uranium series ages of around 15 and 18 ka for bovid teeth recovered from the latest small tool site of xibaimaying the youngest occurrence of such tools in the region and optically stimulated luminescence osl dating of the earliest typical microblade site youfang 26 29 ka in this study we re dated the xibaimaying site using single grain osl methods and the resulting ages indicate that the cultural layer was deposited 46 3 ka ago during mis 3 more than 20 millennia earlier than previously thought and older also than the so called earliest primitive and typical microblade tools found at zhiyu 31 39 ka cal bp and youfang these new ages for human occupation of xibaimaying remove support for the parallel development of the small tool and microblade industries in the nihewan basin during the upper palaeolithic but reliable age estimates from additional sites are needed to confidently infer the nature of the chronological relationship between these two upper palaeolithic industries and the associated toolmakers

on the seasonal onset of polar mesospheric clouds and the breakdown of the stratospheric polar vortex in the southern hemisphere 1 southern hemisphere sh polar mesospheric clouds pmcs also known as noctilucent clouds have been observed to be more variable and in general dimmer than their northern hemisphere nh counterparts the precise cause of these hemispheric differences is not well understood this paper focuses on one aspect of the hemispheric differences the timing of the pmc season onset observations from the aeronomy of ice in the mesosphere satellite indicate that in recent years the date on which the pmc season begins varies much more in the sh than in the nh using the canadian middle atmosphere model we show that the generation of sufficiently low temperatures necessary for cloud formation in the sh summer polar mesosphere is perturbed by year to year variations in the timing of the late spring breakdown of the sh stratospheric polar vortex these stratospheric variations which persist until the end of december influence the propagation of gravity waves up to the mesosphere this adds a stratospheric control to the temperatures in the polar mesopause region during early summer which causes the onset of pmcs to vary from one year to another this effect is much stronger in the sh than in the nh because the breakdown of the polar vortex occurs much later in the sh closer in time to the pmc season

luminescence dating in less than ideal conditions case studies from klasies river main site and duinefontein south africa abstract luminescence dating results are reported for two south african archaeological sites where changes in the dose rate through time are apparent a subtraction procedure involving analysis of both quartz and potassium feldspar extracts is applied to detect and correct for these changes at the middle stone age site of klasies river the dose rate changes inferred from geologic evidence for shell dissolution turn out not to be significant having occurred rapidly after deposition the dates here range from 50 115 ka in broad agreement with other evidence the important howiesons poort component here appears to date somewhat later about 55 60 ka than at several other sites in south africa at the acheulian site of duinefontein the dose rate changes also thought to be caused by shell dissolution are on the other hand very significant the subtraction ages here 125 300 ka agree with independent chronological assessments

rethinking the origin of microblade technology a chronological and ecological perspective abstract there are four hypotheses on the origin of microblade technology in north china i that it originated from siberia before the last glacial maximum ii that it emerged in siberia after the last glacial maximum iii that it developed from the long narrow flakes produced by the long established knapping tradition in north china and iv that it had multi regional origins among which a microblade industry may have emerged from the bipolar technology in northern china based on archaeological data from siberia mongolia the japanese archipelago korean peninsula and north china it is reasonable to say that the technological groundwork of siberia was more substantial and the initial microblade technology appeared in siberia earlier than in the other areas microblade technology was involved in core preparation systematic knapping soft hammer and indirect pressure flaking techniques which were all present in the blade technology in siberia but hardly ever evidenced in the traditional flaking technology systems in north china it is well accepted that the microblade technology was closely related the high mobility of foragers to live in harsh environments the climatic fluctuations of the last glacial in siberia were more severe than in low latitudes and placed greater subsistence pressure on hunter gatherers in siberia the advantages of the initial microblade technology in dealing with these hostile circumstances encouraged foragers to employ and develop it and finally generated its widespread use during the upper paleolithic through human migration and cultural transmission in northeast asia and north america

laboratory shock emplacement of noble gases nitrogen and carbon dioxide into basalt and implications for trapped gases in shergottite eeta 79001 abstract basalt samples have been analyzed mass spectrometrically for shock implanted noble gases n2 and co2 after exposure to 20 60 gpa 200 600 kbar shock in the presence of 0045 3 0 atm of ambient gas isotopically labelled gases were used in some samples to distinguish implanted atmospheric gases from contaminant or indigenous gases abundances of emplaced gases varied linearly with ambient gas pressure for constant shock pressure and gas emplacement was most efficient in the range of 35 50 gpa shock pressure uncrushed samples shocked in this range gave emplacement efficiencies number densities of gases in shocked samples number densities in ambient gas of 2 0 6 7 for heavy noble gases and nitrogen while powdered samples with higher effective porosity yielded 40 50 efficiencies indicating that 50 of noble gases and nitrogen available in porespaces was emplaced no elemental or isotopic fractionation was detected with ar kr xe or n2 helium and in some samples ne were lost by diffusion subsequent to shock emplacement efficiencies for co2 averaged a factor of 1 8 0 2 greater than those of n2 and noble gases in 4 samples with 20 50 gpa shock and yielded 3 2 times greater efficiency in a sample shocked to 60 gpa enhanced co2 emplacement is thought to be due to reaction with silicate materials data from shergottite eeta 79001 glass may be consistent with co2 efficiencies a factor of 2 3 greater than noble gas efficiencies trapped gases in eeta 79001 glass were probably emplaced by shock however apparent emplacement efficiencies are somewhat higher than even shocked powder samples possible explanations for the difference include atmospheric overpressure at the time of shock trapping of gas already in vugs by intruding melt material or collapse of gas filled vugs to form gas laden glass inclusions not enough is yet known about the behavior of vugs under shock to discount the latter possibility

examining histology to identify burned bone abstract early research suggests that examination of the microscopic internal structure is a valid method for distinguishing burned from unburned bone in the archaeological record this study compares burned and unburned modern bones with archaeological bones from sibudu cave ca 60 000 years ago and cave of hearths over 200 000 years ago to more fully describe the heat induced histological changes to bone we also explore the effects of diagenesis on those changes to determine if histological evidence of burning preserves through fossilisation and diagenetic processes and can be successfully used to identify ancient burning application of this technique can help in addressing various issues including the origins of controlled use of fire and understanding animal butchery and disposal