late quaternary chronostratigraphic framework of terraces and alluvium along the lower ohio river southwestern indiana and western kentucky usa abstract the lower ohio river valley is a terraced fluvial landscape that has been profoundly influenced by quaternary climate change and glaciation a modern quaternary chronostratigraphic framework was developed for the lower ohio river valley using optically stimulated luminescence osl dating and allostratigraphic mapping to gain insights into the nature of fluvial responses to glacial interglacial stadial interstadial transitions and holocene climate change river deposits t0 youngest to t7 oldest were mapped along a 75 km reach of the lower ohio river and were dated using 46 osl and 5 radiocarbon samples the examination of cores combined with osl and radiocarbon dating shows that fluvial sediments older than marine oxygen isotope stage mis 2 are present only in the subsurface aggradation during mis 6 illinoian glaciation filled the valley to within 7 m of the modern floodplain and by 114 ka mis 5e sangamon interglacial the ohio river had scoured the mis 6 sediments to 22 m below the modern floodplain surface there were no fluvial sediments in the valley with ages between mis 5e and the middle of mis 3 the mis 3 ages 39 ka and stratigraphic position of t5 deposits suggest the ohio river aggraded 8 14 m during mis 4 or mis 3 near the end of mis 3 the ohio river incised the mid last glacial mid wisconsinan deposits 10 m and began aggrading again by 30 ka aggradation continued into mis 2 with maximum mis 2 aggradation occurring before 21 ka which is coincident with the global last glacial maximum lgm as the ohio river adjusted to changing fluxes in sediment load and discharge following the lgm it formed a sequence of fill cut terraces in the mis 2 outwash that get progressively younger with decreasing elevation ranging in age from 21 ka to 13 ka from 14 ka to 13 ka the ohio river rapidly incised 3 m to form a new terrace and by 12 ka at the onset of the holocene the ohio river established a meandering channel pattern the river formed a broad floodplain surface from 12 ka to 6 ka and then incised 1 m and formed a fill cut terrace from 6 ka to 5 ka after 5 ka likely in response to mid holocene drought in north america the ohio river incised 5 m and by 4 ka the river began aggrading again the ohio river has aggraded 4 m since aggradation began at 4 ka the chronostratigraphic framework and reconstructed history developed here suggest that the lower ohio river is highly sensitive to glacial interglacial transitions and abrupt holocene climate change and responds rapidly to these allogenic forcings

paleomagnetic age for hominid fossils at atapuerca archaeological site spain a paleomagnetic investigation at the gran dolina site excavation atapuerca spain shows that the sediments containing the recently discovered human occupation were deposited more than 780 000 years ago near the time of the matuyama brunhes boundary forty one oriented samples were obtained from 22 sites along an 18 meter section of the gran dolina karst filling the lower 16 sites displayed reversed polarity magnetizations whereas the upper six sites were normal the reversal spans the hominid finds at stratigraphic level td6 the aurora stratum and these hominid fossils are therefore the oldest in southern europe

geomagnetic field intensity and reversals during the past four million years a long and continuous record of the geomagnetic field intensity shows that intensity variations are dominated by two modes major episodes of field regeneration prevail on timescales of a few thousand years immediately after most reversals whereas stable polarity states are characterized by a slow 0 5 myr relaxation process reversals can be seen as the consequence of a progressive degradation of the dipole field

reconciling astrochronological and 40ar 39ar ages for the matuyama brunhes boundary and late matuyama chron when five matuyama brunhes m b boundary records from the north atlantic are placed on isotope age models produced by correlation of the 18o record directly or indirectly to an ice volume model the m b boundary lies consistently at the young end of marine isotope stage 19 with a mean age for the midpoint of the reversal of 773 1 ka standard deviation 0 4 kyr 7 kyr younger than the presently accepted astrochronological age for this polarity reversal 780 781 ka two recently proposed revisions of the age of the 40ar 39ar fish canyon sanidine fcs standard to 28 201 0 046 ma and 28 305 0 036 ma would adjust 40ar 39ar ages applicable to the m b boundary and other reversals and excursions back to 1 2 ma to ages older than the new astrochronological ages by 8 24 kyr the variables used to construct the ice volume models cannot account for the discrepancy the fcs standard age that best fits the astrochronological ages is 27 93 ma which is within the uncertainty associated with the commonly used value of 28 02 0 16 ma but younger than the recently proposed fcs ages the edc2 and edc3 age models in the dome c antarctic ice core yield ages of 771 7 ka and 766 4 ka respectively for the 10be flux peak that denotes the paleointensity minimum at the reversal boundary implying that the edc2 rather than edc3 age model is consistent with the observations from marine sediments at least close to the m b boundary

amphibole 40ar 39ar geochronology from the okcheon metamorphic belt south korea and its tectonic implications abstract an understanding of the okcheon metamorphic belt omb in south korea is central to unraveling the tectono metamorphic evolution of east asia amphibole bearing rocks in the omb occur as calcsilicate layers and lenses in psammitic rocks in the psammitic rocks themselves and in the mafic volcanic layers and intrusives most amphiboles fail to show 40 ar 39 ar plateau ages those that do have ages ranging from 132 to 975 ma the disturbed age pattern and wide variation in 40 ar 39 ar ages can be related to metamorphic grade retrograde chemical reactions excess ar and amphibole composition the oldest age 975 ma can be interpreted either as an old igneous or metamorphic age predating sedimentation or a false age caused by excess ar the youngest age of 132 ma and the disturbed age pattern found in amphiboles from rocks located close to jurassic granitoids are the result of retrograde thermal metamorphic effects accompanying intrusion of the granitoids some medium or coarse grained amphiboles in the calcsilicates are aggregates of fine grained crystals as a result they are heterogeneous and prove to be readily affected by excess ar a disturbed age pattern in amphiboles from the calcsilicates occurring in the high grade metamorphic zone may also be the product of excess ar on the other hand the disturbed pattern of amphiboles present in the calcsilicates from the low grade metamorphic zone could arise from both excess ar and mixed ages however amphiboles from psammitic rocks and some calcsilicates in the high grade metamorphic zone and in intrusive metabasites display real plateau ages of 237 to 261 ma the temperature conditions in the high grade metamorphic zone were higher than the argon closing temperature for amphibole and the amphiboles in this zone give plateau ages only when they are homogeneous in composition lack excess ar and have not been thermally affected by intrusion of the granitoids the unmodified 40 ar 39 ar ages prove rather younger than the age of the late paleozoic metamorphic event of 280 to 300 ma but they are close to muscovite k ar ages of 263 to 277 ma these 40 ar 39 ar amphibole ages are interpreted as the time of cooling that followed the main regional intermediate p t metamorphic climax the results demonstrate that interpretation of 40 ar 39 ar amphibole ages in an area subjected to several metamorphic events can be accomplished only by undertaking a thorough tectono metamorphic study accompanied by detailed chemical analysis of the amphiboles

the kamikatsura event and the matuyama brunhes reversal recorded in lavas from tjornes peninsula northern iceland abstract we report paleomagnetic results from four overlapping stratigraphic sections 55 flows through the lava pile in tjornes peninsula north iceland the initial aim of our study was to check the existence of intermediate directions previously interpreted as belonging to the matuyama brunhes geomagnetic reversal mbr and complete this record with thellier thellier paleointensity determinations and 40ar 39ar radioisotopic dating the directional results corroborate the findings by kristjansson et al 1988 a sequence of reversed transitional normal and transitional polarity r t n t is found in each section the polarity change is characterized by a jump from reversed virtual geomagnetic poles vgps to a quasi cluster of transitional vgps located over china followed by a second jump to a cluster of normal polarity before moving again towards intermediate polarities reversely magnetized flows exhibit a magnetic mineralogy well suited for paleointensity determination of these 25 flows 20 yielded paleointensity estimates of good quality unfortunately the systematic presence of coarse multidomain md titanomagnetite in the transitional and normal polarity flows hampered paleointensity estimates for these flows the virtual dipole moments vdm calculated for the reversed polarity flows vary from 4 9 to 7 0 1022 am2 with an arithmetic mean value of 5 5 0 8 1022 am2 this value is identical to the mean vdm obtained for the 0 3 5 ma time window and thus strengthens the conclusion that the recent geomagnetic field strength is anomalously high compared to that older than 0 3 ma 40ar 39ar isochron ages were obtained with the incremental heating technique on groundmass separates or phenocryst poor whole rock samples six of the transitionally magnetized lavas yielded isochron ages that are indistinguishable from one another at the 95 confidence level the weighted average age is 862 51 ka in the upper part of this volcanic sequence the normally magnetized flows yielded a weighted average age of 787 40 ka this finding supports the conclusion that a geomagnetic excursion within the matuyama chron is recorded in the lower part of the tjornes volcanic sequence whereas only the latest portion of the mbr is recorded by flows in the upper part of the lava pile this conclusion is supported via comparison of the vgps obtained from the lavas with those predicted by a geomagnetic field model

geomagnetic dipole strength and reversal rate over the past two million years independent records of relative magnetic palaeointensity from sediment cores in different areas of the world can be stacked together to extract the evolution of the geomagnetic dipole moment1 2 and thus provide information regarding the processes governing the geodynamo so far this procedure has been limited to the past 800 000 years 800 kyr ref 3 which does not include any geomagnetic reversals here we present a composite curve that shows the evolution of the dipole moment during the past two million years this reconstruction is in good agreement with the absolute dipole moments derived from volcanic lavas which were used for calibration we show that at least during this period the time averaged field was higher during periods without reversals but the amplitude of the short term oscillations remained the same as a consequence few intervals of very low intensity and thus fewer instabilities are expected during periods with a strong average dipole moment whereas more excursions and reversals are expected during periods of weak field intensity we also observe that the axial dipole begins to decay 60 80 kyr before reversals but rebuilds itself in the opposite direction in only a few thousand years

the preparation and conservation treatments of the human fossils from lower pleistocene unit td6 gran dolina site atapuerca the 2003 2009 record abstract the lower pleistocene unit td6 at the gran dolina site sierra de atapuerca burgos spain has yielded human remains attributed to homo antecessor many of these require some conservation treatment after recovery in order to be visible and consistent enough to be studied safely handled and preserved in this paper we report the conservation tasks carried out on the human fossils collected during the second period of the excavation of unit td6 2003 2011 the main problems with these fossils are derived from the karst sediment filling in which they are found essentially made up of clays silt and gravels that may be compacted and cemented and occasionally solidly adhered to the bones in short the treatments consisted of removing the matrix with manual and automatic tools consolidating and rebuilding the fossils the extent of treatments was adapted to the needs of the research and the entire process as well as the fossils before and after the intervention were strictly recorded with this paper we primarily aim to provide information that often remains unpublished and to share procedures that may be applied to fossils with similar problems but in describing these treatments we also aim to show that remedial conservation methodology is based equally on the mastery of the techniques and materials used for treatment and on the knowledge of fossils and the requirements of the studies conducted on them

characterizing hyena coprolites from two latrines of the iberian peninsula during the early pleistocene gran dolina sierra de atapuerca burgos and la mina barranc de la boella tarragona abstract coprolites are commonly identified in the pleistocene archaeo palaeontological record they have often been described as indirect evidence for the presence of carnivores usually hyenids during the formation of a depositional sequence however coprolites are a much larger source of information that can provide data relating to factors affecting an archaeological assemblage including its taphonomic history and palaeoecology in this paper two fossil coprolite accumulations dating to the late early pleistocene are described level td6 1 of gran dolina sierra de atapuerca burgos and unit ii of la mina barranc de la boella tarragona the results highlight the morphological homogeneity of these hyena coprolites despite a considerable variation in size the presence of microspherulites is clearly identified in all of the analysed hyena coprolites their composition is rich in elements characteristic of bone origin such as calcium ca and phosphorus p a major difference however differentiating the remains from these sites was a higher frequency of bone fragments in the la mina coprolites regarding to td6 1 pollen spores and palynomorphs are scarce in the samples from both sites which in fact share similar ecological characteristics such as the presence of pine wild grasses and coprophilous fungi hyena coprolites are relatively easy to differentiate from those of other taxa however they show intra specific similarities in their micro and macro morphology and composition despite their wide size range the species of hyenids responsible for the coprolites is not possible to identify based exclusively on the size range and the importance of a multidisciplinary study of the latrines and the coprolites is discussed as a source of palaeoecological and taphonomic information in this study coprolites are analysed compared and attributed to a hyenid identified as crocuta crocuta in the case of td6 1 but without specific attribution in the case of la mina

a new astronomical timescale for the loess deposits of northern china here we present a refined timescale for the entire sequence of quaternary chinese loess which relies upon the correlation of detailed monsoon records to the astronomical solution of laskar 1990 and the oceanic odp677 18o record of shackleton et al 1990 the chronological scheme considers in detail the relative structures of the palaeoclimatic and palaeomagnetic records to produce an accurate timescale that is consistent with the current understanding of loess depositional and post depositional processes analysis of this chronological framework demonstrates downward displacement of the palaeomagnetic horizons with respect to the climatic record

thermoluminescence dating of sediments older than 100 ka abstract for several years attempts have been made to establish reliable procedures for thermoluminescence tl dating of sediments older than 100 ka disagreement persists among tl workers about which procedures are reliable for which sediments two recent reports have demonstrated that tl ages up to 800 ka for polymineral fine silt loess and up to 600 ka for quartz from beach dune sands agree well with expected ages several factors that apparently have influeneed negatively the accuracy of other results are use of ultraviolet tl emissions use of the regeneration tl procedures for feldspar bearing samples use of a single preheating procedure and use of a peak integration procedure rather than an equivalent dose plateau test consideration of published data suggests that more attention should be paid to the variable emissions intensity glow curve shapes signal lifetimes from discrete grains within subsamples the effects of such variability would probably account for the failure of peak integration and single preheating procedures to yield expected equivalent dose values single grain or micro tl studies of feldspar and quartz tl both spectral emission and glow curve measurements are recommended as aids to further understanding of current tl sediment dating practices

geomagnetic excursions and paleointensities in the matuyama chron at ocean drilling program sites 983 and 984 iceland basin 1 we report natural remanent magnetization nrm directions and geomagnetic paleointensity proxies for part of the matuyama chron 0 9 2 2 ma interval from two sites located on sediment drifts in the iceland basin at ocean drilling program sites 983 and 984 mean sedimentation rates in the late matuyama chron are 15 9 and 11 5 cm kyr 1 respectively for the older part of the record 1 2 ma oxygen isotope data are too sparse to provide the sole basis for age model construction the resemblance of the volume susceptibility record and a reference 18o record led us to match the two records to derive the age models this match based on site 983 984 susceptibility is consistent with available site 983 984 benthic 18o data paleointensity proxies were derived from the slope of the nrm versus anhysteretic remanent magnetization plot for alternating field demagnetization in the 30 60 mt peak field range paleointensity lows correspond to polarity reversals at the limits of the jaramillo olduvai cobb mountain and reunion subchrons and to seven excursions in nrm component directions magnetic excursions defined here by virtual geomagnetic polar latitudes crossing the virtual geomagnetic equator are observed at 932 1048 1115 1190 1215 cobb mountain subchron 1255 1472 1480 1567 1575 gilsa subchron and 1977 ka the results indicate that geomagnetic directional excursions associated with paleointensity minima are a characteristic of the matuyama chron and probably of polarity chrons in general

the santa rosa event 40ar 39ar and paleomagnetic results from the valles rhyolite near jaramillo creek jemez mountains new mexico the jaramillo event was originally defined by doell and dalrymple in 1966 on the basis of k ar ages from sanidine in the normally transitionally and reversely magnetized rhyolite domes named cerro del abrigo cerro santa rosa i and cerro santa rosa ii respectively that erupted following collapse of the archetypal valles caldera new mexico we have collected new paleomagnetic data from the three domes and new 40 ar 39 ar laser fusion and furnace incremental heating experiments on sanidine crystals from the cerro santa rosa i rhyolite step wise alternating field and thermal demagnetization techniques applied to 52 samples from seven sites indicate that the original paleomagnetic results of doell and dalrymple science 152 1966 1060 1061 are valid cerro del abrigo is normally magnetized whereas the santa rosa i dome is transitional with an inclination of 363 toward the east and the santa rosa ii dome is of reversed polarity twenty five laser fusion experiments on sanidine crystals from the the cerro santa rosa i dome together with the saddle shaped spectrum obtained by incrementally heating the sanidine in a furnace reveal that this rhyolite contained a small but significant component of excess argon prior to eruption our preferred age of 936 8 ka 2c for the santa rosa i rhyolite is based on the concordant laser fusion isochron and incremental heating plateau ages this age is significantly older than was inferred on the basis of earlier laser fusion 40 ar 39 ar results that suggested a trapped component characterized by a 40 ar 36 ar ratio lower than the atmospheric value of 295 5 our new age distinguishes the santa rosa i dome by 65 kyr from the termination of the jaramillo normal subchron 1001 10 ka and by 37 kyr from basaltic lavas at haleakala and tahiti which record the kamikatsura event 899 6 ka moreover this determination is a factor of three more precise than the best previous estimate for a proposed geomagnetic event in this time period the cerro santa rosa i rhyolite dome once intimately linked with the end of the jaramillo event and the acceptance of plate tectonic theory now defines a highly resolved feature the santa rosa event in a terrestrial geomagnetic reversal time scale that is consistent with the global record of magnetic field intensity from marine sediments fl 2002 elsevier science b v all rights reserved

esr dating applied to optically bleached quartz a comparison with 40ar 39ar chronologies on italian middle pleistocene sequences abstract the geological sequences of numerous lower and middle palaeolithic sites of central and southern italy found in fluvio lacustrine contexts and rich both in archaeological and palaeontological remains have recorded various volcanic events all along the middle pleistocene timescale these sedimentary sequences made of detritic and volcanic materials are suitable to compare independent numerical geochronological methods and thus develop a multi method approach relying especially esr method applied to optically bleached fluvial quartz and the 40ar 39ar on single grain isotopic method applied to potassium feldspars in this present paper geochronological data obtained using these two methods were used on several middle pleistocene italian sites including volcanic and fluvial but also archaeological levels isoletta and lademagne in lazio and notarchirico in basilicata in this contribution esr age estimates were performed using a multi centre approach from al ti li and ti h centres we demonstrate for these sites that esr based framework is overall consistent with the 40ar 39ar chronology that over the 700 and 350 ka time window this comparison validates the multi centre approach proposed and demonstrates that the use of ti h for samples with equivalent doses higher than 280 300 gy leads to systematic age underestimates

magnetostratigraphy of plio pleistocene sediments in a 1700 m core from osaka bay southwestern japan and short geomagnetic events in the middle matuyama and early brunhes chrons abstract a magnetic polarity stratigraphy spanning more than the past 3 2 myr was determined for a long 1545 m continuous sedimentary sequence of marine fluvial and lacustrine deposits from the osaka basin southwestern japan additionally two short geomagnetic reversal events were identified a short event at about 0 69 ma lasting for about 7 kyr in the early brunhes chron around the lower boundary of a marine clay deposited during a period of eustatic high sea level during the marine oxygen isotope stage 17 and another short matuyama event 1 60 1 58 ma correlated with stage 54 event and the early stage of the sangiran excursion accumulation rate was 0 3 0 4 mm yr from 3 to 2 ma and then increased by about 50 with a rate of 0 51 mm yr during the olduvai subchron high values of 0 59 mm yr were maintained from the upper olduvai boundary to the brunhes matuyama boundary from 1 77 to 0 78 ma with a peak at 0 74 mm yr during the jaramillo subchron these changes in accumulation rate probably reflect the history of tectonic subsidence of the drilling site the magnetic polarity stratigraphy provides a chronological framework for sedimentological paleoenvironmental tephrochronological and tectonic studies of the osaka basin

insights into the age of the mono lake excursion and magmatic crystal residence time from u th he and 230 th dating of volcanic allanite we present new data for the age of the mono lake excursion at its type locality using the u th he system on allanite we dated wilson creek ash 15 lajoie 1968 to 38 7 1 2 ka 2 se the new age for this ash supports the hypothesis kent et al 2002 zimmerman et al 2006 that the mono lake excursion is coincident with and probably the same event as the laschamp geomagnetic excursion 40 4 2 ka an event that shares similar magnetic characteristics with the excursion identified at mono lake we also estimate an allanite magma residence time of slightly less than 30 ka based on 230 th 238 u disequilibrium and the u th he based eruption age

biochronology of spanish quaternary small vertebrate faunas abstract thousands of fossils of small vertebrates are recorded in one of the most complete stratigraphic sequences of the continental european pleistocene in the sierra de atapuerca this sequence with a few interruptions spans the last 1 5 million years the stratigraphic series is recorded in six karstic cavities in the sierra de atapuerca from the oldest record to the most modern one these are the sima del elefante gran dolina galeria zarpazos sima de los huesos el portalon and el mirador the faunal successions of continental microvertebrates have made it possible to divide the atapuerca sequence into 7 faunal units atapuerca faunal units ata fus which are based on the first and last local appearances of taxa lo ho the spanish quaternary small vertebrate faunas are grouped into 5 distinct biozones from the oldest to the most recent allophaiomys pliocaenicus allophaiomys lavocati allophaiomys chalinei iberomys brecciensis and iberomys cabrerae these are calibrated with radiometric and palaeomagnetic dating allowing the proposal of a continental biochronological scale for the pleistocene of the iberian peninsula

matuyama brunhes reversal and kamikatsura event on maui paleomagnetic directions 40 ar 39 ar ages and implications abstract eighty nine basaltic lava flows from the northwest wall of haleakala caldera preserve a concatenated paleomagnetic record of portions of the matuyama brunhes m b reversal and the preceding kamikatsura event as well as secular variation of the full polarity reversed and normal geomagnetic field they provide the most detailed volcanic record to date of the m b transition the 24 flows in the transition zone show for the first time transitional virtual geomagnetic poles vgps that move from reverse to normal along the americas concluding with an oscillation in the pacific ocean to a cluster of vgps east of new zealand and back finally to stable polarity in the north polar region all but one of the 16 kamikatsura vgps cluster in central south america the full polarity flows with 40ar 39ar ages spanning a total of 680 kyr pass a reversal test and give an average vgp insignificantly different from the rotation axis with standard deviation consistent with that for other 0 5 ma lava flows of similar latitude precise 40ar 39ar dating consisting of 31 incremental heating experiments on 12 transitional flows yields weighted mean ages of 775 6 1 9 and 900 3 4 7 ka for the m b and kamikatsura transitional flows respectively this matuyama brunhes age is 16 kyr younger than ages for m b flows from the canary islands tahiti and chile that were dated using exactly the same techniques and standards suggesting that this polarity transition may have taken considerably longer to complete and been more complex than is generally believed for reversals

a relative geomagnetic paleointensity stack from ontong java plateau sediments for the matuyama we present a stack of geomagnetic paleointensity estimates for the matuyama chron 0 778 2 582 ma sedimentary magnetizations from 4 ocean drilling program odp cores from the ontong java plateau ojp are analyzed with thermal techniques thellier thellier experiments are used to determine magnetic properties and indicate that a thermal treatment to 250 c can be used for paleointensity estimates the correlated records form a coherent ojp stack which is dated at reversal boundaries a coherent feature with two other data sets spanning the matuyama chron is the occurrence of a 150 kyr cyclicity however the time control of the ojp stack is not accurate except for the 10 tie points at the reversals this could at least in part explain why the three matuyama paleointensity records show no other coherent frequencies

reassessing the age of atapuerca td6 spain new paleomagnetic results we carry out a new paleomagnetic study across stratigraphic layer td7 of gran dolina site atapuerca and reassess the existing absolute ages thermoluminescence electron spin resonance obtained at this site the new and more detailed magnetostratigraphic record of the matuyama brunhes boundary combined with absolute ages enables further constraint on the age of the underlying human bearing level or aurora stratum paleomagnetism of the studied silts and sandstones reveals stable dual polarity characteristic remanent magnetization directions a new normal magnetic polarity short interval is found at several consecutive sampling localities in the upper part of td7 providing a new ante quem date for the human bearing sediments of 0 9 ma possibly formed during mis 25

magnetostratigraphic dating of the huojiadi paleolithic site in the nihewan basin north china the fluvio lacustrine sequences in the nihewan basin northern china provide important terrestrial archives of paleoclimate and paleoenvironment as well as an important source of paleolithic settlements and therefore early human occupation in the eastern old world magnetostratigraphic dating of the sequences has permitted the precise timing of the basin infilling and associated paleolithic and mammalian fauna sites here we report new magnetostratigraphic results that place stringent age controls on the huojiadi paleolithic site in this basin partially oxidized magnetite and hematite were identified as the major carriers for the characteristic remanent magnetizations magnetostratigraphic results show that the huojiadi sequence recorded the very late matuyama reverse chron and the jaramillo normal subchron the stone artifact layer resides in the jaramillo normal subchron yielding an estimated age of around 1 0 ma for the huojiadi paleolithic site furthermore by combining our magnetostratigraphy and previously published magnetochronology data a magnetochronological sequence of the early pleistocene paleolithic sites in the nihewan basin has been established the chronological sequence implies that early humans may have persistently colonized the high latitude temperate areas in the eastern old world such as the nihewan basin during the early pleistocene

evidence for the kamikatsura and santa rosa excursions recorded in eolian deposits from the southern chinese loess plateau 1 a detailed paleomagnetic investigation of a loess paleosol sequence in baoji southern chinese loess plateau reveals two distinct geomagnetic excursions accompanied by inferred relative paleointensity minima in the late matuyama chron rock magnetic experiments demonstrate that the sediments of the excursion intervals in loess unit l9 have the same magnetic properties as those from surrounding normal and reversed polarity intervals assuming constant sedimentation rate between the jaramillo matuyama and matuyama brunhes magnetic polarity boundaries the midpoint ages and durations for these two excursions are estimated at 0 89 ma and 16 kyr and 0 92 ma and 7 kyr respectively in addition these two events are separated by an interval with fully reversed polarity that had a duration of 16 kyr these estimates are supported by paleoclimatologically inferred age constraints the two excursions are probably correlated with the kamikatsura and santa rosa excursions respectively

ubiquity of anomalous fading in k feldspars and the measurement and correction for it in optical dating anomalous fading rates were measured in k feldspars separated from 49 sediment samples mainly from north america the intensity of the optically stimulated luminescence was found to decrease linea

the matuyama brunhes boundary interval 500 900 ka in north atlantic drift sediments summary ocean drilling program odp sites 984 and 983 located on north atlantic sediment drifts provide high resolution records across the matuyama brunhes boundary at odp site 984 bjorn drift iceland basin the mean sedimentation rate in the 500 900 ka interval is 12 cm kyr 1 based on an age model derived by matching the planktonic and benthic oxygen isotope records to an ice volume model the matuyama brunhes polarity transition at site 984 as defined by virtual geomagnetic polar vgp latitudes 50 has an apparent duration of 7 kyr with a mid point at 773 5 ka compared with 772 5 ka at neighbouring site 983 outside the polarity transition at both sites 984 and 983 excursions in vgp latitudes to values 20 at 540 590 and 670 ka correspond to troughs in the palaeointensity record new u channel palaeomagnetic data across the matuyama brunhes boundary for working and archive halves of core sections from three holes at both sites 984 and 983 augment data published by channell lehman 1997 and are compared with back to back 1 cm 3 discrete samples clusters of vgps in the south atlantic and northeast asia in both u channel and discrete sample records imply that polarity transition fields have characteristics similar to the modern non axial dipole nad field

40ar 39ar age constraints for the jaramillo normal subchron and the matuyama brunhes geomagnetic boundary our mid pleistocene 4oar 39ar age recalibration of the geomagnetic polarity timescale is nearly in accord with the oxygen isotope climate record calibration of the astronomical timescale proposed by johnson 1982 and shackleton et al 1990 4oar 39ar ages of a normally magnetized rhyolite dome in the valles caldera northern mexico yielded a weighted mean age of 1 004 0 019 ma a k ar age of 0 909 0 019 ma for this rock by doell and dalrymple 1966 was the linchpin for the recognition and calibration of the jaramillo normal subchron jns other 4oar 39ar ages from the vailes caldera and 4oar 39ar ages of ivory coast tektites indicate that the jns began at about 1 11 ma and ended before 0 92 ma probably near 0 97 ma the matuyama brunhes boundary occurred between 0 79 ma and 0 76 ma on the basis of 4oar 39ar sanidine ages from 1 three reversely magnetized rhyolite domes of the valles caldera 0 793 0 018 ma 0 794 0 007 ma and 0 812 0 023 ma and pumice 0 789 0 006 ma from the reversely magnetized oldest toba tuff of sumatra and 2 pumice 0 764 0 005 ma and 0 757 0 009 ma from the lower and upper units of the normally magnetized bishop tuff the age of the boundary may be close to 0 77 ma as deduced from rates of sedimentation in ancient lake bonneville utah increasingly aware that the polarity of earth s magnetic field has changed repeatedly through geologic time and isotopic dating of these polarity reversals resulted in a geomagnetic polarity time scale gpts for the late cenozoic this combined paleomagnetic and isotopic research played a pivotal role in confirming plate tectonic theory glen 19821 which revolutionized the earth sciences continual refinement of isotopic ages which define the gpts has increased the usefulness of geomagnetic polarity reversals as marker hori zons in many types of geologic studies we present 4oar 39ar data and ages for some key volcanic units that support changes in the isotopic age chronology of the gpts using volcanic rocks erupted near the time of the geologically youngest two geomagnetic polarity reversals figure 1 the older of the two reversals originally called by doell and dalrymple 1966 the jaramillo event is now named the jaramillo normal subchron jns it is recorded in middle pleistocene rocks as a brief episode of normal polar ity within the late matuyama chron the younger of the two called the matuyama brunhes boundary mbb is regis tered in middle pleistocene rocks worldwide and consists of

revisions to the age of the brunhes matuyama boundary and the pleistocene geomagnetic polarity timescale the currently referenced age of 730 ka for the brunhes matuyama b m geomagnetic polarity boundary mankinen and dalrymple 1979 is based largely on k ar and paleomagnetic data from postcollapse rhyolites in the valles caldera new mexico doell and dalrymple 1966 doell et al 1968 dating of sanidine from valles rhyolites by the 40a 39ar laser fusion technique indicates that samples critical to defining the b m boundary are up to 90 ka older than previously thought the new data combined with earlier results yield an age for the b m boundary of 780 10 ka 40ar 39ar ages from other samples suggest the jaramillo normal polarity subchron extended from 1010 to 915 ka

ungulate carrying capacity in pleistocene mediterranean ecosystems evidence from the atapuerca sites abstract large herbivore carrying capacity that is the maximum biomass of large herbivorous mammals that an ecosystem is able to sustain for the long term is a key factor in ecosystems trophic dynamics the carrying capacity of pleistocene ecosystems conditioned the survival opportunities and colonization capabilities of hominin populations in europe in this study we use the amphibian and squamate record of two early and middle pleistocene sites from sierra de atapuerca spain to obtain estimates of past temperature and rainfall values a function derived from the analysis of a wide set of recent mammalian communities is used to infer the large herbivore carrying capacity of the atapuerca ecosystems during the pleistocene from those climatic variables this function provides reliable estimates of large herbivore carrying capacity in open environments but not in forest communities the results presented in this study indicate that carrying capacity was higher at atapuerca during most of the sequence than in the present our data also suggest that in most mediterranean ecosystems large herbivore biomass is currently below the carrying capacity of the environment due to the relatively low diversity of the large herbivore guild in most recent communities although the carrying capacity was high at atapuerca in the periods the area was occupied by humans it was also high in other periods for which no evidence of human presence has been recorded thus the relationship between human occupation of the territory and carrying capacity does not appear to be simple

the acheulean from atapuerca three steps forward one step back abstract in western europe acheulean cultural evidence is well attested by ca 0 5 ma however recent work has proven that it was present earlier at the end of the early pleistocene the timing and mode of the western european acheulean needs still to be investigated and this knowledge appears to be strongly dependent upon data from sites with sufficiently well preserved archeo stratigraphical sequences and or geophysical conditions that guarantee reliable dating the karstic deposits from the sierra de atapuerca burgos spain represent one such case they contain exceptionally long and continuous archeo paleontological deposits that have yielded hominins stone tools and faunal remains from a period covering the late early pleistocene up to the holocene previous work has allowed us to reconstruct the evolution of technology on a local scale from the late early to the middle pleistocene and to situate the appearance of the acheulean more or less simultaneously in the sites of galeria gran dolina td10 and the sima de los huesos at around 0 5 ma after a hiatus of archeological evidence of approximately 300 ka these acheulean assemblages appear in association with hominin fossils that have recently been identified as early members of the neandertal lineage delving further into the description of the acheulean from atapuerca we have recently focused on the technological features that we consider to be of particular evolutionary significance and attempted to identify them in other european key sites of comparable chronologies indeed we identified some internal evolutionary trends which led us to propose that there was a local transition at atapuerca from the acheulean to the early middle paleolithic techno complexes however the chronological setting resulting from the intensive dating programs carried out in the galeria and sima de los huesos sites and especially the correlation of these dates with the ones available from gran dolina td10 confronts us with some apparent paradoxes underlining the need to reconsider the technological interpretation of the lithic technical record from atapuerca while great efforts are being made in dating and analysis at many european middle pleistocene sites as well as in establishing correlations with which to build consistent regional sequences single long continuous and accurately excavated i e over a large surface area archeological successions remain crucial to properly interpret the appearance and evolution of the acheulean throughout europe we further stress the importance of taking into account conditioning factors such as raw material availability environmental constraints and site function issues

relative geomagnetic paleointensity from the jaramillo subchron to the matuyama brunhes boundary as recorded in a mediterranean piston core piston core lc07 located west of the sicily strait in the mediterranean sea unambiguously records the matuyama brunhes m b and the upper jaramillo polarity reversals with similar average sediment accumulation rates sars for the brunhes chron 2 29 cm kyr and late matuyama chron c1r 1r 2 19 cm kyr we report a relative paleointensity record for the interval spanning the m b boundary down into the jaramillo subchron which is unique in the mediterranean because existing records from this basin cover only the last 80 kyr the average sar in core lc07 is used to translate the depth related paleointensity record to the time domain the ratio of anhysteretic remanent magnetization to low field magnetic susceptibility is climatically sensitive and is used to tune the age model this correlation produces a good fit to the global ice volume model derived for summer insolation at 65 n with this age model a paleointensity minimum in association with the m b boundary has a duration of about 4 5 kyr while the directional change has a duration of 6 3 kyr a second paleointensity minimum of similar duration is found about 16 kyr below the m b boundary this feature precursor or dip in the literature has previously been recognized at the same time interval in many marine records which reinforces the validity of our age model other relative paleointensity minima are found within chron c1r 1r and within the uncertainties of the respective age models these minima coincide with those observed from the few published coeval paleointensity records in particular there is good correspondence between the ages of minima at about 0 92 and 0 89 ma which probably correlate with two geomagnetic excursions santa rosa and kamikatsura respectively that have been recorded in lava flows and dated using the 40 ar 39 ar technique in contrast a recently dated excursion at 0 83 ma from la palma seems to correspond to a paleointensity maximum this observation is opposite to that expected and this excursion needs to be confirmed in contrast to some recently published paleointensity records spectral analysis of the lc07 record does not reveal identification of significant power at the orbital obliquity frequency fl 2002 elsevier science b v all rights reserved

dating transitionally magnetized lavas of the late matuyama chron toward a new 40ar 39ar timescale of reversals and events the k ar based geomagnetic polarity timescale was constructed using data from lavas and tuffs that bracketed but rarely dated the transitions between polarity intervals subsequent 40ar 39ar dating indicated that the ages of some polarity transitions had been underestimated by about 6 although the accepted ages of the polarity chron boundaries have increased their precise temporal definition remained uncertain we have taken a different approach and used incremental heating techniques to obtain 18 new 40ar 39ar ages from basaltic lavas within flow sequences at punaruu valley tahiti and haleakala volcano hawaii these lavas record transitional paleomagnetic directions corresponding to four mid pleistocene polarity reversals or events three lavas from punaruu valley previously thought to record the cobb mountain normal polarity subchron cmns gave a mean age of 1 105 0 005 ma indicating that they were erupted about 76 kyr after the cmns this period of transitional field behavior is designated the punaruu event in addition seven new 40ar 39ar ages from the punaruu valley indicate that the jaramillo normal polarity subchron jns lasted about 67 kyr starting at 1 053 0 006 ma and ending 0 986 0 005 ma this agrees with astronomical estimates but conflicts with jns ages proposed by spell and mcdougall 1992 and izett and obradovich 1994 on the basis of 40ar 39ar dating of rhyolite domes in the valles caldera indistinguishable 40ar 39ar ages of seven lavas including one from punaruu valley and six from haleakala that record broadly similar intermediate paleodirections suggest that the kamikatsura event occurred at 0 886 0 003 ma moreover these data indicate that the kamikatsura event occurred 20 40 kyr after another geomagnetic event most probably taking place at 0 92 ma we designate this earlier field behavior the santa rosa event adopting its name from that of a transitionally magnetized rhyolite dome which happened to figure prominently in the original definition of the end of the jns in the 1968 study of doell et al 1968 the discovery of these new short lived polarity events during the matuyama reversed chron suggests that the 400 kyr period between 1 18 and 0 78 ma experienced no less than 7 and perhaps more than 11 attempts by the geodynamo to reverse this newly determined higher frequency of geomagnetic activity illustrates vividly the importance of obtaining precise age control directly from transitionally magnetized rocks

applications and limitations of thermoluminescence to date quaternary sediments abstract the thermoluminescence tl method dates sediment by quantifying time dependent dosimetric properties of mineral grains sunlight exposure of the sediment during transportation and deposition or heating resets the tl clock to time zero after burial of the mineral grains ionizing radiation from the decay of radioisotopes imparts a tl signal this accumulated tl signal is proportional to the equivalent dose ed which is a measure of radiation exposure during the burial period a tl age estimate is determined from the ratio of the ed to the environmental radiation dose rate the calculation of an ed is influenced by the susceptibility of sediments to optical bleaching the emission spectra of minerals and possible long and short term fading there are three basic methods for determining an ed regeneration total and partial bleach the regeneration technique may yield under estimates because of sensitivity changes with laboratory bleaching the latter two techniques are most useful for well and partially light bleached sediments respectively a number of sediments can be dated by the tl method eolian and a variety of terrestrial sediments yield apparently accurate tl age estimates though there are possible complications associated with pedogenesis it appears that some fluvial sediment can be accurately dated by tl but little is known about the efficiency of optical bleaching for fluvial depositional systems till and glacier proximal deposits are inadequately light bleached to be dated by tl sediments deposited distal from the glacier margin which are at least partially bleached are preferred for dating future research is needed to understand better the relationship between sedimentary environments and the extent of light bleaching also studies should concentrate on dating feldspar extracts from well dated sequences to more fully ascertain the temporal limitations of the method only by understanding the interplay of sedimentology tl dosimetry and environmental radiation can the tl method be effectively applied to the myriad of depositional environments spanning the late to middle pleistocene

new palaeoenvironmental and palaeoclimatic reconstructions for the middle palaeolithic site of cuesta de la bajada teruel eastern spain inferred from the amphibian and squamate reptile assemblages abstract in the eastern iberian peninsula the archaeological site of cuesta de la bajada teruel spain has produced some of the earliest evidence of middle paleolithic stone tool traditions together with evidence of equid and cervid carcasses defleshed by hominins based on the numerical age of 317 240 ka derived from osl esr and aar dating methods for the lower part of the cuesta de la bajada sedimentological sequence level cb3 as well as the biochronological inferences for the small and large mammal associations the site can be attributed to marine isotope stage mis 8 or the end of mis 9 as amphibians and reptiles have precise environmental and climatic requirements and do not differ at species level from the extant herpetofauna of the iberian peninsula they can contribute to the reconstruction of the landscape and climate in this paper the fossil amphibians and squamate reptiles from cuesta de la bajada are studied for the first time the mutual ecogeographic range and habitat weighting methods were applied to the herpetofaunal assemblages to estimate quantitative data for the landscape and climate reconstructions the climate is shown to have been colder and wetter than today in the interior of eastern spain with mean annual temperature up to 2 5 c lower and mean annual precipitation slightly higher than at present the monthly climatic reconstruction shows differences in the distribution of precipitation over the course of the year with more abundant precipitation from late autumn to spring i e from october to may and more or less similar precipitation to today during the summer months july and august this suggests there was stronger rainfall seasonality between winter and summer than currently occurs the paleoenvironmental reconstruction based on the herpetofaunal assemblage depicts a poorly forested 15 20 patchy landscape with a large representation of dry meadows and scrubland habitats together with well evidenced aquatic habitats these reconstructions are consistent with other proxies recovered at cuesta de la bajada pollen small and large mammals as well as other european mis 8 9 paleoclimatic records we can thus correlate levels cb2 and cb3 with the later part of mis 8 265 257 ka or with a humid fluctuation within the mis9b 303 290 ka it is also possible to provide a new description of the environmental and climatic conditions that occurred in inner spain during a cold period of the late middle pleistocene

optical dating studies of quartz and feldspar sediment extracts abstract continuing developmental work into optical dating has led to some clarification of the optical behaviour of quartz and feldspar sediment extracts we have verified the key assumption intrinsic to the method that the optical signal is zeroed completely upon exposure to daylight we also show that the rate of zeroing in optical dating is much more rapid than it is in tl dating studies concerned with the extraction of the thermally stable signal from laboratory irradiated samples showed that problems may arise from medium to high temperature preheating of young samples optical alternatives to thermal stabilization were tested using dye and krypton lasers using a krypton laser we have succeeded in obtaining an equivalent dose of 0 0 0 7 gy for the quartz from a modern intertidal sand and an average dose of 120 22 gy for the feldspar extract of a 70 ka sand unit both were obtained using six wavelengths from the infrared to the violet and no dependence on wavelength was found we found that the photon energies of infrared and deep red light can stimulate luminescence in unirradiated quartz and feldspar extracts of sediments this was not expected and suggests that the process of trap emptying is more complex than we had envisioned but implies a far greater than expected degree of technical flexibility for the optical dating method

the lower early middle pleistocene small debitage productions in western europe new data from isernia la pineta t 3c upper volturno basin italy abstract isernia la pineta archaeological site in central italy dated to about 0 6 ma is one of the earliest archaeological sites of the italian peninsula and one of the key sites for the knowledge of human behaviour during the early middle pleistocene in western europe several archaeostratigraphic units have been recognized and systematically excavated core and flake assemblages were studied as a bulk in the eighties of last century with a typo metrical approach not taking into account a precise stratigraphic provenance here we present a review of the lithic collection from the lowermost archaeostratigraphic unit t 3c which is the first techno economic analysis based on the concept of chaine operatoire our results contrast with those from previous studies our analysis demonstrates that the technical criteria employed in small debitage are not opportunistic and unstructured as previously inferred by contrast they correspond to well established mental templates that led knappers 1 to use mainly a discoid method 2 to apply this debitage method regardless of the size and shape of the original matrix 2 to maintain a high productivity and 3 to produce medium sized flakes to be turned into small tools the new data are discussed in the framework of the lower early middle pleistocene technological complexes of western europe calling into question a number of allegations about the first technical traditions that have been previously accepted without reservation

biostratigraphy paleomagnetism and geology of the orce ravine southern spain comment on the paper by gibert et al 2006

paleointensity record from pleistocene sediments 1 4 0 ma off the california margin high resolution magnetic measurements of 45 m of sediment from the delgada fan area at ocean drilling program site 1021 39 5 n 127 46 w were performed in order to extract a reliable signal of relative paleointensity a detailed chronology was established by correlation of the magnetic susceptibility variations to the insolation curve for the past 1 4 myr covered by the record the remanence carrier is pseudo single domain sized magnetite that varies in concentration by a factor 3 stepwise alternating field demagnetization isolated a very stable natural remanent magnetization nrm which showed the succession of the cobb and jaramillo subchrons and directional changes associated with the punaruu event 1 105 ma two techniques have been used to extract the signal of relative paleointensity a significant climatic component remained present in the curve obtained from the slopes of the nrm versus the anhysteretic remanent magnetization arm in contrast the nrm and the susceptibility k lf both being driven by orbital forcing normalization by susceptibility is not contaminated by climatically driven changes and is thus taken as our best estimate of relative paleointensity comparison with other high resolution records and compilations reinforces the actual geomagnetic origin of the variations displayed by the nrm k signal overall this record confirms the succession of distinct highs and lows which are concomitant with full field reversals and short term geomagnetic events present during the matuyama chron the presence of large oscillations of the field with no periodicity confirms that the geomagnetic field at least his dipolar part is highly unstable and may have remained in this mode for a long period of time

assessing automated image analysis of sand grain shape to identify sedimentary facies gran dolina archaeological site burgos spain abstract gran dolina is a cave sierra de atapuerca spain infilled by a 25 m thick sedimentary record divided into 12 lithostratigraphic units that have been separated into 19 sedimentary facies containing early and middle pleistocene hominin remains in this paper an automated image analysis method has been used to study the shape of the sedimentary particles since particle shape is interpreted as the result of sedimentary transport and sediment source this study can provide valuable data about the sedimentological mechanism of sequence formation the shape of the sand fraction in 73 samples from gran dolina site and sierra de atapuerca was analyzed using the malvern morphologi g3 an advanced particle characterization tool in this first complete test we used this method to the published sequence of gran dolina defined previously through field work observations and geochemical and textural analysis the results indicate that this image analysis method allows differentiation of the sedimentary facies providing objective tools to identify weathered layers and measure the textural maturity of the sediments channel facies have the highest values of circularity and convexity showing the highest textural maturity of particles on the other hand terra rossa and debris flow samples show similar values with the lowest particle maturity

the early middle pleistocene palaeoenvironmental change based on the squamate reptile and amphibian proxies at the gran dolina site atapuerca spain abstract although still ongoing the archaeological and palaeontological excavations in the gran dolina cave sierra de atapuerca burgos every year since 1976 have already revealed a long culturally and palaeontologically rich sequence dated by biostratigraphy esr u series and the palaeomagnetic record at between roughly 1 my and 250 ky gran dolina has one of the longest and most continuous vertical profiles the section 19 m thick divided into 11 stratigraphic levels represents a time span of nearly 700 000 years the gran dolina sequence was partially excavated during a preliminary evaluation of its archaeological and palaeontological richness this excavation known as the gran dolina sondeo south lasted from 1993 to 1999 hominin remains were unearthed in 1994 from level 6 of gran dolina and level 6 was dated to somewhat more than 780 ky based on palaeomagnetic and microfaunal evidence making these the oldest known hominins in europe given the importance of this discovery every effort is being made to reconstruct the landscapes where these hominins once thrived the gran dolina sondeo south tds has furnished a great number of microvertebrate remains and of these around 40 000 bones are attributed to amphibians and squamates the faunal list of the squamates and amphibians of the tds comprises at least 22 species a diversity similar to what exists nowadays in spain triturus sp alytes obstetricans pelobates cultripes pelodytes punctatus bufo bufo bufo calamita hyla arborea rana temporaria rana cf dalmatina rana cf iberica pelophylax ridibunda sp blanus cinereus lacerta s l small sized indeterminate lacertids anguis fragilis natrix natrix natrix maura coronella austriaca coronella cf girondica rhinechis scalaris vipera cf aspis and vipera cf latasti these ectotherm vertebrates show variations in their taxonomic diversity throughout the sequence although they do not differ specifically from the extant herpetofauna of the iberian peninsula they do so in the composition of their taxonomic assemblage when the squamates and amphibians of tds are grouped by habitat categories the habitat weightings method and studied in terms of their vertical evolution throughout the sequence it is possible to follow environmental changes across the early middle pleistocene transition results from the squamate and amphibian studies indicate that the landscape had open habitats in the vicinity of the atapuerca caves throughout the sequence with wet points in the surrounding area open dry microhabitats were more developed during warm periods whereas during cold periods the environment was slightly more humid and wooded these results are compared with studies in small mammals pollen analysis and geomorphology giving a scenario for the palaeoclimatic and palaeoenvironmental changes that occurred during the early to middle pleistocene boundary in atapuerca and hence a scenario for the hominins that once lived in the sierra de atapuerca

luminescence dating applications in geomorphological research abstract chronological control remains critical to the interpretation of environmental change and to establishing long term rates of geomorphological processes radiocarbon dating will continue to be the central technique for age assessment of carbon bearing sediments deposited in the last ca 40 ka but alternative absolute dating strategies are required for older or non carbon bearing sediments they include uranium series dating of precipitated sediments k ar and ar ar dating of primary volcanic materials and cosmogenic isotopic dating of surface exposure ages an additional family of methods collectively termed luminescence techniques is increasingly providing a basis for the age assessment of detrital sedimentary deposits these methods directly date the deposition of detrital mineral grains typically quartz and feldspar and have been demonstrated to provide accurate deposition chronologies for up to 800 ka although 150 ka is more typical in the past decade a subset of luminescence techniques which employ optical sample stimulation methods called optical dating has made it possible to date samples from a much wider range of depositional systems given that the methods directly date sedimentation they allow direct assessment of depositional dynamism in numerous terrestrial and subaqueous including marine sedimentary systems and have demonstrated particular potential in the elucidation of chronologies from aeolian dune and loess fluvial colluvial coastal and volcaniclastic environments this paper provides a summary of the principles of the luminescence especially optical dating methods and shows how recent developments specifically single aliquot dating procedures have dramatically enhanced the scope and potential of the method the luminescence techniques are increasingly being incorporated into a wide range of geomorphological studies which seek to establish the nature of landscape changes over the past interglacial glacial cycle and beyond

magnetostratigraphic age of the xiantai paleolithic site in the nihewan basin and implications for early human colonization of northeast asia timing of the early habitation and stone technologies in the nihewan basin north china has provided insights into our understanding of early human adaptability to high northern latitudes in east asia here we contribute to this topic with detailed magnetostratigraphic investigation coupled with mineral magnetic measurements and palynological analyses on a lacustrine sequence in this basin which contains the xiantai paleolithic site magnetite and hematite were identified as the main carriers for the characteristic remanent magnetizations magnetostratigraphic results show that the xiantai lacustrine sequence recorded the brunhes chron the jaramillo and the olduvai subchrons and successive reverse polarity portions of the intervening matuyama chron stratigraphic correlation in terms of lithology magnetic susceptibility and magnetic polarity sequences between the xiantai and xiaochangliang sections indicates that the xiantai artefact layer is readily contemporary with the xiaochangliang artefact layer which has been previously estimated to be about 1 36 ma r x zhu k a hoffman r potts c l deng y x pan b guo c d shi z t guo b y yuan y m hou w w huang earliest presence of humans in northeast asia nature 413 2001 413 417 early humans of the xiantai paleolithic site lived in a steppe paleoenvironment indicated from fossil pollens furthermore the combined evidence of our magnetostratigraphy and previously published magnetochronology and paleoclimate data documents that early humans of north china were able to adjust to an increasing variability of paleoclimates and paleoenvironments over the early pleistocene

paleomagnetic record at odp site 980 feni drift rockall for the past 1 2 myrs 1 a detailed record of variations in the direction and intensity of the geomagnetic field over the past 1 2 myrs has been obtained from an 120 m thick sedimentary section cored at odp site 980 on the feni drift north atlantic the record has high resolution due to high mean sedimentation rates 11 3 cm kyr for the brunhes chron and 5 5 cm kyr for the matuyama chron paleomagnetic measurements every 1 cm along u channel samples and high quality isotopic age control the iceland basin event is manifest by virtual geomagnetic poles crossing the equator at 190 ka the base of the recovered section lies immediately below the cobb mountain subchronozone that occurs within marine isotope stage 35 normalized remanence data can be correlated to paleointensity records from odp sites 983 and 984 700 km to the nw from site 980 and with lower resolution paleointensity data from the pacific ocean differences between the site 980 paleointensity record and the pacific records are attributed to variable sedimentation rates variable quality age control and inadequacies in the normalization procedure used to derive the paleointensity proxies

one million years of cultural evolution in a stable environment at atapuerca burgos spain abstract the present paper analyses the evidence provided by three sites sima del elefante gran dolina and galeria located in the trinchera del ferrocarril of the sierra de atapuerca these three sites are cave infillings that contain sediments deposited from approximately 1 2 ma to 200 kyr pollen herpetofauna and small and large mammal remains are used as proxies to obtain a general picture of the environmental changes that occurred at the sierra de atapuerca throughout the one million year period represented at these sites similarly cultural changes are tracked analyzing the evidence of human behavior obtained from the study of several bone and lithic assemblages from these three sites at least three periods with different cultural features involving technology subsistence and behavior are determined from the available evidence the first two periods correspond to the mode 1 technology and homo antecessor the first is dated around 1 2 to 1 0 ma and reflects opportunistic behavior both in technology and subsistence the second period is around 800 kyr bp mode 1 technology is still maintained but subsistence strategies include systematic hunting and the use of base camps the third period is dated between 500 ka and 200 ka and corresponds to the mode 2 technology and the acquisition of directional hunting and other organizational strategies by homo heidelbergensis a transition from mode 2 to mode 3 seems to appear at the end of this time range and may reflect the early phases of a fourth cultural change with regard to the environment our main conclusion is that there was an absence of extremely harsh conditions at atapuerca throughout this time period the presence of mediterranean taxa was constant and the dominant landscape was a savannah like open environment probably with small forest patches an alternation of mediterranean and mesic species as the dominant component of the tree storey was induced by the climatic cycles and steppes spread across the landscape during the drier periods in any case it is not possible to establish clear cut off points separating entirely different environmental episodes our results show no evidence of any relationship between environmental change and cultural change at the sierra de atapuerca

geomagnetic palaeointensities and astrochronological ages for the matuyama brunhes boundary and the boundaries of the jaramillo subchron palaeomagnetic and oxygen isotope records from odp site 983 we have measured relative geomagnetic palaeointensity proxies palaeomagnetic directions and 18 o for the 700 1100 ka interval from odp site 983 gardar drift north atlantic where mean sedimentation rates are ca 13 cm kyr 1 the age model was generated by matching the benthic 18 o data to the ice volume model and confirmed by tuning the precessional components of both signals for the matuyama brunhes boundary mbb and the boundaries of the jaramillo subchronozone the duration of the polarity reversal process defined by virtual geomagnetic polar latitudes of less than 45 is ca 5 kyr whereas the generally accepted astrochronological estimates for the boundaries of the jaramillo subchronozone lie within the polarity transitions as recorded at site 983 the astrochronological age for the matuyama brunhes polarity transition 780 ka is ca 5 kyr older than the onset of this transition at site 983 775 ka the polarity reversals lie within palaeointensity lows with abrupt recovery of palaeointensity post reversal there is no progressive sawtooth decrease in palaeointensity within the jaramillo subchronozone or between the top of the jaramillo and the mbb but rather within polarity chrons several short intervals of low palaeointensity which sometimes coincide with high amplitude secular variation orbital 100 and 41 kyr periods are present in the palaeointensity record as they are not obviously attributable to climate lithology in these records they may be a feature of the geomagnetic field itself

geomagnetic excursions reflect an aborted polarity state abstract geomagnetic excursions represent short episodes of a few thousand years at most during which the field considerably exceeds its normal range of variability during a polarity state paleomagnetic records have now been obtained with extremely high temporal resolution which have improved our knowledge of these short events we have compiled the most detailed records of excursions that had occurred during the brunhes and matuyama chrons we show that virtual geomagnetic poles vgps of at least one record of each event are able to reach the opposite polarity in the next step we have computed different simulations of excursions during which the dipole progressively vanishes before growing back without reversing this scenario produces very few reversed directions which are only visible at some latitudes we infer that it is impossible to reach the ratio of reversed to intermediate vgps present in the paleomagnetic records if the excursions were not associated with a short period of reversed dipole field therefore excursions should be regarded as two successive reversals bracketing an aborted polarity interval we propose that the same underlying mechanisms prevail in both situations excursions or reversals and that below a certain strength the field reaches an unstable position which preludes either the achievement of a reversal or its return to the former polarity

refining the chronology of acheulean deposits at porto maior in the river mino basin galicia spain using a comparative luminescence and esr dating approach abstract trapped charge dating of optically bleached quartz which involves techniques such as electron spin resonance esr and thermally transferred optically stimulated luminescence tt osl is increasingly being used to establish middle and early pleistocene chronologies for archaeological palaeontological and palaeoenvironmental sedimentary sequences comparative dating studies that make use of several independent or semi independent radiometric techniques in tandem are an invaluable means of assessing the reliability of optically bleached quartz dating methods and ascertaining empirical relationships between different quartz dating signals in this study we undertake a comparative dating evaluation of single grain tt osl and various esr signals that exhibit different optical resetting properties al ti li and where measurable ti h centres at the middle pleistocene archaeological site of porto maior northwest spain which contains a distinctive regionally significant acheulean stone tool assemblage we expand the existing chronological framework for porto maior using single grain tt osl dating derive combined numerical ages for individual depositional units using bayesian modelling and further examine the relationship between esr and tt osl signals by reviewing a range of published comparative dating studies the new single grain tt osl ages obtained for unit pm3 at porto maior 225 31 ka and 242 32 ka are in close agreement with previously published esr ti li ages for this unit 266 23 ka and 279 26 ka and significantly younger than those reported for the al centre 441 75 ka and 452 66 ka our broader comparison of published tt osl esr dating results also shows statistically significant agreement between single grain tt osl and ti li centre ages in other sedimentary settings suggesting a potentially closer relationship between the tt osl producing traps and the ti li paramagnetic centres in quartz rather than between the tt osl and al centre signals the bayesian modelling results for porto maior enable us to refine the existing bracketing depositional age for the archaeological accumulation at porto maior and provide a stronger statistical foundation for chronostratigraphic correlations with other acheulean archaeological deposits found in the mino river basin the bayesian model indicates that the entire porto maior sedimentary sequence was deposited between 312 6 32 6 ka and 18 8 7 7 ka and that the in situ large cutting tool assemblage from level pm4 most likely accumulated during marine isotope stage 7 mean depositional age 210 7 24 7 ka the results of this study reinforce the usefulness of applying the multiple centre mc esr dating approach in many dating contexts and demonstrate the value of undertaking comparisons between semi independent quartz dating signals in order to maximise the reliability of esr and single grain tt osl quartz chronologies

palaeoenvironment and dating of the early acheulean localities from the somme river basin northern france new discoveries from the high terrace at abbeville carriere carpentier dating the earliest human occupations in western europe and reconstructing links with climatic and environmental constraints is a central issue in quaternary studies amongst the discovery of palaeolithic artefacts ascribed to the early pleistocene in southeast britain and central france the somme basin where the acheulean type site amiens saint acheul is located is a key area for addressing this topic research undertaken over the past 20 years on both quaternary fluvial and loess sequences of this area has provided a unique dataset for the study of the relations between human occupations and environmental variations studies based on an interdisciplinary approach combining sedimentology palaeontology and geochronology have highlighted the impact of the 100 kyrs cycles on terrace formation during the last million years in this terrace system the earliest in situ acheulean settlements known in the 1990s were dated to early mis 12 450 ka but new field discoveries at amiens rue du manege dated to 550 ka significantly increase the age of the oldest human occupation in the area in this context new fieldwork has been undertaken in abbeville at the carriere carpentier site famous for its white marl deposit attributed to the cromerian and in the same terrace level where the former discoveries of abbevillian bifaces were made by d ault du mesnil this research is based on an interdisciplinary approach combining sedimentology paleontology dating esr on quartz and esr u series on teeth and archaeology according to the various bio proxies molluscs large vertebrates small mammals the white marl was deposited during the early part of an interglacial phase in an aquatic slow flowing environment as emphasized by the development of oncoliths and the presence of fish and aquatic molluscs the landscape was composed of a mosaic of open bush and forest areas in which wet and grassy vegetation developed on riverbanks on the basis of terrace stratigraphy esr and esr u series dating results and biostratigraphic data the fluvial deposits of the white marl can be securely attributed to mis 15 in addition some acheulean bifaces were discovered at the base of the slope deposits directly overlying the fluvial sequence these artefacts are most likely coeval with the end of mis 15 or an early stage of mis 14 between 550 and 500 ka and represent together with the artefacts from amiens rue du manege the oldest in situ evidence of acheulean occupation in northern france however no unquestionable artefacts have been discovered in the white marl or in the underlying gravel layer these discoveries contribute to the chronology of the earliest evidence of hominin occupations in north western europe which may be related to homo heidelbergensis

the nature of technological changes the middle pleistocene stone tool assemblages from galeria and gran dolina subunit td10 1 atapuerca spain this article focuses on the origins for technological variation during the middle pleistocene through the analysis of the lithic assemblages from galeria and gran dolina subunit td10 1 atapuerca spain the technological study was organized into three main levels of analysis the first stage consisted of the technological characterization of the whole assemblage e g the general composition of each sample the exploitation and shaping methods used and the characteristics of each item the second stage involved the morphometric analysis of the large tools mainly handaxes and cleavers given the significance of these instruments in middle pleistocene assemblages in this case we combined traditional technical and metrical analyses with current morphometric methods lastly taking into account the general characteristics of these sites the third stage consisted of assessing how the different occupational strategies affected the lithic representation these analyses allowed us to define three technological groups the first includes unit galeria giia which corresponds to the appearance of the acheulean in the atapuerca caves the second is represented by the rest of the sequence of the galeria site mainly the upper part of the sequence unit giii and the third technological corresponds to gran dolina subunit td10 1 thus the galeria sequence shows the technological evolution of the acheulean over a period of 250 ka furthermore subunit td10 1 represents a new occupational strategy combining traditional acheulean tools with more evolved technical strategies

filling in the gaps the contribution of non pollen palynomorphs to knowledge about the local environment of the sierra de atapuerca caves during the pleistocene abstract for several decades conventional pollen analyses have been supplemented with information provided by non pollen palynomorphs npp generally the taxa included in this group are microalgae fungi insects and arachnid s chitinous remains as well as plant debris and other organic palynomorphs of undetermined origin that are valuable tools with which to characterise the original strata as well as the local environmental features that influence deposit formation processes in this work we present the results of the npp analysis of the archaeological and palaeontological deposits of sima del elefante gran dolina and galeria all of which are located in the trinchera area sierra de atapuerca burgos spanning a period from 200 ka to almost 1 5 million years ago the npp analysis of the three deposits has provided information about the presence of decayed organic matter accumulations erosion processes and moisture conditions knowledge of palynomorphs contributes to the understanding of the biological physical and chemical dynamics that resulted in different sedimentary sequences in almost all cases there is a clear connection between the major stratigraphic trends established for the three deposits and the npp assemblages identified however the eminently local character of the dispersion of most of the palynomorphs identified has prevented the interrelation between the three sequences analysed