the position of paleopedology in geosciences and agricultural sciences abstract paleopedology is a relatively young science with roots in various older geosciences at present it suffers from a lack of clear definitions and fundamental principles nevertheless it has considerable potential for applications in stratigraphy paleontology sedimentology archeology paleoclimatology seismology geomorphology soil classification and agriculture consequently it could play a major coordinating role in soil science especially in contributing to a natural strongly genetic system of soil classification we suggest that such a system with emphasis on development of soil properties in relation to current and past environmental factors would be of greater value in all these subjects than the current systems designed principally for agricultural interpretation

continental ichnofossil assemblage from the upper silurian of laurentia the bloomsburg formation of eastern pennsylvania abstract few unequivocal silurian examples of continental ichnofossils have been reported in eastern pennsylvania the upper silurian bloomsburg formation consists of fluvial deposits that have yielded a low diversity ichnofauna described here the rarity of reported silurian continental ichnofauna the quality of the recovered ichnofossil specimens as well as the richly descriptive sedimentary and palaeontological context makes this discovery significant by expanding our understanding of continental ichnodiversity and affirming ichnotaxa reported elsewhere the bloomsburg formation ichnofauna now suggests the possibility that there was a cosmopolitan global ichnofauna of relatively low ichnodiversity in continental especially fluvial paleoenvironnments during the late silurian the fluvially deposited bloomsburg formation is characterized by erosively based fining up sequences from medium grained sandstone to mudstones channel fills are dominated by ripple laminated strata and thinner graded beds floodplain deposits are characterized by thinly laminated graded beds consisting of fine grained siltstones to mudstones thicker laminated mudstones contain reduction halos around ribosome traces mudcracks and some well developed bk horizons of calcisols the bloomsburg fluvial systems thus were low gradient systems that built extensive floodplain deposits and were transitional between low and high sinuosity fluvial systems the strata contain a low diversity invertebrate ichnofauna that includes 1 sinuous traces palaeophycus 2 bilobate oval traces rusophycus 3 slightly sinuous traces with a medial ridge and scratches cruziana 4 two rows of parallel circular or ellipsoid depressions diplichnites 5 substrate penetrating burrows not identified and 6 traces of fossil plant roots palaeophycus and substrate penetrating burrows are the dominant ichnofossils in the bloomsburg formation the bloomsburg formation ichnofauna adds an important datapoint in western laurentia to the distribution of the biota of the freshwater ecosystem of the late silurian it also well represents the epifaunal arthropod ichnofauna of the diplichnites ichnoguild of the scoyenia ichnofacies developed in fluvial environments during the silurian to devonian

determining the burial time of single grains of quartz using optically stimulated luminescence abstract in the optical dating of sediments it is usually assumed that the optically stimulated luminescence osl signal has been completely reset by light exposure prior to burial this assumption is often not valid one approach to testing and perhaps circumventing this assumption is to examine the apparent date of last exposure to daylight of individual sediment grains this paper reports on the application for the first time of 2 new measurement protocols to the estimation of the radiation dose received during burial for individual quartz grains from an aeolian deposit of known age 10 000 year old which is considered likely to have been completely reset by sunlight at deposition additive dose laboratory doses added to the burial dose before osl measurement and regenerative dose doses added after measurement of osl from burial dose single aliquot protocols are applied to 28 and 25 individual grains respectively each grain provides an independent estimate d e of the burial dose the average d e from the additive dose protocol 21 8 1 1 gy is in good agreement with the average from the regenerative dose protocol 23 8 1 0 gy both agree well with 1 13 multiple grain regenerative dose single aliquot measurements each on 1 mg sub samples of 23 9 0 3 gy 2 9 multiple grain additive dose single aliquot measurements also on 1 mg sub samples of 22 4 0 7 gy and 3 one previously published multiple aliquot additive dose estimate of 23 5 0 6 gy using 52 sub samples each of 5 mg the resulting optical ages are in good accord with 14 c and thermoluminescence age determinations the distribution of equivalent doses in the single grains is however unexpectedly large 23 of mean d e given the very likely complete resetting of the osl signal at deposition possible reasons are discussed and it is concluded that heterogeneity in beta dosimetry is the most likely explanation the single grain optical dating protocols reported here allow a detailed examination of the dose distribution in very small samples thus they should enable accurate dates to be obtained for sediments and soils that contain poorly bleached or mixed age components as well as deposits in which quartz grains are present in extremely low abundance

meteoric diagenesis below a submerged platform implications for δ13c compositions prior to pre vascular plant evolution middle ordovician alabama u s a abstract the middle ordovician chickamauga formation at red mountain expressway rme and tidwell hollow twh sections in alabama u s a has a complex early diagenetic history early diagenetic history of the buildup facies consisted of two phases of marine cementation separated by two generations of meteoric equant calcite with moldic dissolution separating equant calcite generations a third generation of meteoric equant drusy calcite is present after secondary marine diagenesis equant drusy calcite is interpreted as meteoric because its stable isotopic composition 13 c 0 1 to 1 6 18 o 4 8 to 7 3 is too variable to be accounted for by marine or mixing zone precipitation equant drusy calcite from buildup facies is mostly non luminescent and non ferroan this is unlike early ferroan equant calcite dull to bright luminescent from below the unconformity that overlies the chickamauga formation at rme meteoric diagenesis below the unconformity is unrelated to early diagenesis in the underlying buildup facies equant drusy calcite from the buildup facies at rme has a covariation of 13c and 18o values that forms a truncated inverted j and has elevated mg values these geochemical signatures indicate precipitation at a site that was distal from the recharge zone meteoric diagenesis at rme occurred during rising relative sea level and flow of meteoric fluids under a submerged platform is the only mechanism able to reconcile available stratigraphic petrologic and geochemical data ordovician meteoric 13c values from twh and other formations are slightly depleted 2 4 relative to coeval marine carbonate especially when compared with post silurian meteoric carbonate minor depletion of ordovician carbonate is the result of limited generation of light soil gas co2 before the development of vascular plants

factors controlling the geochemical evolution of fumarolic encrustations valley of ten thousand smokes alaska abstract factor and canonical correlation analysis of geochemical data from eight fossil fumaroles suggest that six major factors controlled the formation and evolution of fumarolic encrustations on the 1912 ash flow sheet in the valley of ten thousand smokes vtts the six factor solution model explains a large proportion low of 74 for ni to high of 99 for si of the individual element data variance although the primary fumarolic deposits have been degraded by secondary alteration reactions and up to 75 years of weathering the relict encrustations still preserve a signature of vapor phase element transport this vapor phase transport probably occurred as halide or oxyhalide species and was significant for as sb and br at least three and possibly four varied temperature leaching events affected the fumarolic deposits high temperature gases liquids heavily altered the ejecta glass and mineral phases adjacent to the fumarolic conduit as the fumaroles cooled fe rich acidic condensate leached the ejecta and primary fumarolic deposits and resulted in the subsequent precipitation of fe hydroxides and or fe oxides low to ambient temperature leaching and hydration reactions generated abundant hydrated amorphous phases up to 87 of the individual element data variance is apparently controlled by the chemistry of the ejecta on which the relict encrustations are found this matrix chemistry factor illustrates that the primary fumarolic minerals surrounding the active vtts vents observed by earlier workers have been effectively removed by the dissolution reactions element enrichment factors calculated for the vtts relict encrustations support the statistical factor interpretations on the average the relict encrustations are enriched relative to visibly unaltered matrix protolith in as br cr sb cu ni pb fe and loi an indirect measure of sample h 2 o content

optical dating of deep sea sediments using single grains of quartz a comparison with radiocarbon abstract in this paper we demonstrate that optical dating of single grains of quartz offers an alternative means of dating deep sea sediments the precision and accuracy of the technique which has the potential to date sediments deposited during the last 500 000 years or so is limited by the random and systematic uncertainties associated with producing optical ages these result in total relative age uncertainties of between 10 and 20 at the 68 confidence interval which are similar in size to those associated with late quaternary oxygen isotope chronologies we analysed single grains of quartz from several depth intervals down core fr10 95 gc17 which was collected offshore from cape range peninsula western australia from a water depth of 1093 m in the eastern indian ocean the single grain optical ages are shown to be consistent with ams radiocarbon ages obtained from planktonic foraminifera from the same core we also show that marine sediments are not immune from partial or heterogeneous bleaching incomplete resetting of the optical dating signal where partial or heterogeneous bleaching of the optical dating signal is indicated we recommend that single grain dating be employed and the burial dose estimated from the population of grains with the lowest absorbed radiation dose

marine derived 14c calibration and activity record for the past 50 000 years updated from the cariaco basin abstract an expanded cariaco basin 14c chronology is tied to 230th dated hulu cave speleothem records in order to provide detailed marine based 14c calibration for the past 50 000 years the revised high resolution cariaco 14c calibration record agrees well with data from 230th dated fossil corals back to 33 ka with continued agreement despite increased scatter back to 50 ka suggesting that the record provides accurate calibration back to the limits of radiocarbon dating the calibration data document highly elevated 14c during the glacial period carbon cycle box model simulations show that the majority of observed 14c change can be explained by increased 14c production however from 45 to 15 ka 14c remains anomalously high indicating that the distribution of radiocarbon between surface and deep ocean reservoirs was different than it is today additional observations of the magnitude spatial extent and timing of deep ocean 14c shifts are critical for a complete understanding of observed glacial 14c variability

late quaternary mega lakes fed by the northern and southern river systems of central australia varying moisture sources and increased continental aridity optically stimulated and thermoluminescence ages from relict shorelines along with accelerator mass spectrometer 14c ages from freshwater molluscs reveal a record of variable moisture sources supplied by northern and southern river systems to lake mega frome in southern central australia during the late quaternary additional lacustrine palynological and terrestrial proxies are used to reconstruct a record that extends back to 105 ka confirming that lakes mega frome and mega eyre were joined to create the largest system of palaeolakes on the australian continent as recently as 50 47 ka the palaeohydrological record indicates a progressive shift to more arid conditions with marked drying after 45 ka subsequently lake mega frome has filled independently at 33 31 ka and at the termination of the last glacial maximum to volumes some 40 times those of today further sequentially declining filling episodes to volumes 25 10 those of today occurred immediately prior to the younger dryas stadial in the mid holocene and during the medieval climatic anomaly southern hemisphere summer insolation maxima are a poor predictor of palaeolake filling episodes an examination of multiple active moisture sources suggests that palaeolake phases were driven independently of insolation and at times by some combination of enhanced southern ocean circulation and strengthened tropical moisture sources

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

metamorphosed soils as stratigraphic indicators in deformed terranes an example from the eastern alps amphibolite facies schists of anomalously high aluminum and iron content occur along a major unconformity in the tauern window austria their stratigraphic position is consistent with a weathering or paleosol origin for the protolith this interpretation is supported by geochemical data previous paleosol studies have concentrated on their significance as paleoenvironmental indicators the use of the tauern window schists for this purpose is precluded by their metamorphic grade and degree of deformation however these and other similar metasoils can serve as valuable field indicators in structurally complicated areas

ash deposits in hayonim and kebara caves israel macroscopic microscopic and mineralogical observations and their archaeological implications abstract a study of the hearths and ash layers preserved in hayonim and kebara caves israel showed that they are composed of one or several different minerals these include the polymorph of caco3 calcite a variety of phosphate minerals and a suite of siliceous minerals the major component of the latter are siliceous aggregates that are present in wood detailed studies of the mineral associations in these fossil ash layers as well as in fresh wood ash using optical and scanning electron microscopy in the back scattered electron mode together with elemental analyses showed that ash in these caves undergoes a series of diagenetic changes the best preserved ash layers resemble fresh ash and are composed mainly of calcite with minor amounts of siliceous minerals the calcite reacts with phosphate rich solutions to form carbonated apatite and with time the latter dissolves and a variety of other phosphate containing minerals form with each diagenetic change some of the more soluble minerals are lost and ultimately only the ash derived siliceous minerals remain in both caves there are local accumulations of such siliceous minerals that are metres thick in fact ash derived minerals in general are major components of the sediments in both kebara and hayonim caves their diagenesis involves a hugh reduction in volume which in turn may have important effects on the geological structures and stratigraphy of the sediments the changing mineralogy of the sediments due to diagenesis complicates the use of present day estimates of radiation content of the sediments for correcting age estimates by thermoluminescence and electron spin resonance finally the presence of the relatively stable ash derived siliceous minerals in a sedimentary layer in other caves could be a useful means of identifying the presence of ash in other archaeological sites where macroscopic hearth features are absent

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

the impacts of land plant evolution on earth s climate and oxygenation state an interdisciplinary review abstract the paleozoic emergence of terrestrial plants has been linked to a stepwise increase in earth s o2 levels and a cooling of earth s climate by drawdown of atmospheric co2 vegetation affects the earth s o2 and co2 levels in multiple ways including preferential organic carbon preservation by decay resistant biopolymers e g lignin and changing the continental weathering regime that governs oceanic nutrient supply and marine biological production over shorter time scales 1 myr land plant evolution is hypothesized to have occasionally enhanced p weathering and fertilized the oceans expanding marine anoxia and causing marine extinctions oceanic anoxia would eventually become limited by oceanic o2 uptake as oxygen accumulates in the atmosphere and surface oceans when excess organic carbon is buried in marine sediments here we review hypotheses and evidence for how the evolving terrestrial ecosystems impacted atmospheric and oceanic o2 and co2 from the ordovician and into the carboniferous 485 298 9 ma five major ecological stages in the terrestrial realm occurred during the prolonged time interval when land was colonized by plants animals and fungi marked by the evolution of 1 non vascular plants 2 vascular plants with lignified tissue 3 plants with shallow roots 4 arborescent and perennial vegetation with deep and complex root systems and 5 seed plants the prediction that land vegetation profoundly impacted the earth system is justified although it is still debated how the individual transitions affected the earth s o2 and co2 levels the geological record preserves multiple lines of indirect evidence for environmental transitions that can help us to reconstruct and quantify global controls on earth s oxygenation and climate state

going underground experimental carbonization of fruiting structures under hearths we show that carbonized fruits and seeds recovered from middle stone age deposits in rock shelters are likely to have been carbonized as part of post depositional processes we buried indigenous south african fruits nuts and seeds at pre determined depths and distances from the centers of experimental fires the cold ashes of the hearths and the sand surrounding them were subsequently excavated using standard archaeological techniques and dry screening the fruiting structures from the oxidizing part of the fire were burnt to ashes whereas those buried in sand under anoxic conditions survived in varying forms those buried 5 cm below the center of the fire were carbonized those buried 10 cm below the center of the fire were dehydrated and those 5 cm and 10 cm below the surface at the outer edge of the fire were unaffected size moisture or oil content of the original fruit or seed did not appear to influence whether or not carbonization took place temperatures recorded 5 cm below the experimental fires suggest that the carbonization occurred at or before a maximum temperature of 328 c and also at lower maximum temperatures 152 c that were maintained for long periods even when the quantities of a particular wood are controlled open fires may produce variable underground temperatures and the temperatures below ancient hearths would have been equally variable we suggest that cyperaceae sedge nutlets the most numerous fruiting structures in the sibudu middle stone age archaeobotanical assemblage occur in the shelter as a result of human activity subsequent burial and accidental carbonization when hearths were built directly above the buried nutlets

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

osl dating of the aterian levels at dar es soltan i rabat morocco and implications for the dispersal of modern homo sapiens the aterian is a distinctive middle palaeolithic industry which is very widely spread across north africa its dating and significance have been debated for nearly a century renewed interest in the aterian has arisen because of a recent proposal that its development and spread may be linked to the dispersal of anatomically modern humans the industry contains technological innovations such as thin bifacially flaked lithic points and pedunculates as well as evidence for personal ornaments and use of red ochre such markers as shell beads are believed to be indicative of symbolic behaviour dar es soltan i on the atlantic coast of morocco contains a thick sequence of aterian deposits that were thought to represent the later stages of development of this industry new optically stimulated luminescence dates and geomorphological study indicate a much older sequence and so far the earliest yet recorded ages for the aterian they suggest an appearance in the maghreb region during mis marine isotope stage 5

equivalent dose distributions from single grains of quartz at sibudu south africa context causes and consequences for optical dating of archaeological deposits abstract optical ages for 14 sediment samples collected from the post howiesons poort late middle stone age msa and final msa deposits at sibudu kwazulu natal south africa were reported in a companion paper jacobs z wintle a g duller g a t roberts r g wadley l new ages for the post howiesons poort late and final middle stone age at sibudu south africa journal of archaeological science 2008 these ages were based on equivalent dose d e distributions that were overdispersed in this paper we investigate factors both internal and external to the grains that may contribute to such higher than expected overdispersion in single grain d e values intrinsic factors accounted for some but not all of the observed scatter and application of a set of rejection criteria filtered grains for which erroneous d e values would otherwise be calculated we investigated sediment mixing and differences in the beta dose received by individual grains in their burial environment as two likely reasons for the observed overdispersion the scatter in d e distributions for all the samples is best explained by grains that were deposited at the same time and which were well bleached but that subsequently received a range of beta doses a procedure is presented for adjusting the measured beta dose rate and its associated error we show that using a combination of single grain osl measurements of d e the finite mixture model and adjustment of the beta dose rate result in stratigraphically consistent ages these ages are more consistent than the ages obtained from multiple grain aliquot d e values and the average dose rates for each sample the multiple grain ages are about 10 older partly because of the variable dose rate and partly because these aliquots contained grains with undesirable osl characteristics

late quaternary hillslope evolution recorded in eastern south african colluvial badlands abstract infrared stimulated luminescence irsl ages have been obtained from a sequence of sandy colluvial deposits in northern kwazulu natal comparison of the irsl ages on sand sized potassium rich feldspars with radiocarbon dates on a horizon organic matter from buried palaeosols within the colluvial succession shows good agreement between the dating techniques when compared with palaeoenvironmental records the data suggest that the colluvium accumulated during arid stages of the late quaternary whilst pedogenesis repeatedly occurred at intervals of hillslope stability which may reflect periods of greater humidity temperature does not seem to have been a forcing factor in the landscape development extensive colluviation took place during the arid last glacial maximum but the occurrence of several palaeosols indicates that it was a time of fluctuating climatic conditions

trace fossil evidence for late ordovician animals on land fossil burrows within newly recognized buried soils in the late ordovician juniata formation near potters mills in central pennsylvania represent the oldest reported nonmarine trace fossils they are thought to have been an original part of the soil because their greater density toward the top of the paleosols corresponds with mineralogical microstructural and chemical changes attributed to ancient weathering and because about half the burrows are encrusted with nodular carbonate interpreted as caliche associated fossil caliche the size distribution of the burrows and their w shaped backfills are evidence that the burrows may have been excavated by bilaterally symmetrical organisms that grew in well defined growth increments and were able to withstand desiccation among well known soil organisms millipedes are burrowing animals that satisfy these requirements but have a fossil record not quite this old this trace fossil evidence for animals on land together with recent palynological evidence for land plants of a bryophytic grade of evolution during late ordovician time are indications of terrestrial ecosystems of slightly greater antiquity and complexity than hitherto suspected

radiocarbon dating from 40 to 60 ka bp at border cave south africa abstract we present 21 radiocarbon dates on 19 charcoal samples from the sedimentary sequence preserved in border cave south africa the background radiocarbon activity for charcoal from the cave was determined to be 0 050 0 018 percent modern carbon from the analysis of a radiocarbon dead sample from unit 5wa radiocarbon ages for individual samples ranged from 25 2 to 58 2 ka bp the error weighted mean ages for successively older strata are 38 5 0 85 0 95 ka bp for unit 1wa 50 2 1 1 1 0 ka bp for units 2bs lr a and 2bs lr b 56 5 2 7 2 0 ka bp for unit 2bs lr c and 59 2 3 4 2 4 ka bp for unit 2wa this radiocarbon chronology is consistent with independent chronologies derived from electron spin resonance and amino acid racemization dating the results therefore provide further evidence that radiocarbon dating of charcoal by the abox sc technique can yield reliable radiocarbon ages beyond 40 ka bp they also imply that border cave 5 a modern human mandible predates 58 2 ka bp and that the middle stone age mode 3 later stone age mode 5 transition of border cave was largely effected between 56 5 and 41 6 ka ago

where were the hearths an experimental investigation of the archaeological signature of prehistoric fire technology in the alluvial gravels of the southern plains the interpretation that a rock has been subjected to cultural utilization is a basic element of hunter gatherer research the fracture mechanics of the flaked stone tool production process are well understood and the material residues are routinely identified during fieldwork conversely non percussion processes such as hot rock technology which can result in rock fracture are less well understood an experimental study has been developed to examine the fractured gravels observed at a prehistoric site on the southern plains usa the experiment has sought to determine whether cultural or natural agencies were responsible for the production of the angularly fractured rocks the positive results of the experiment indicate that not only were humans most likely responsible for the breakages but also that the fractured rocks often exhibit distinctive morphologies that may be identified during fieldwork this simple experimental methodology is applicable to other hunter gatherer sites where the depositional environment is not conducive to the structural preservation of features such as hearths

a possible annelid from the trenton limestone ordovician of quebec with a review of fossil oligochaetes and other annulate worms a single specimen of fossil worm from the trenton limestone recovered from a quarry northeast of quebec city may represent a new form that cannot be directly compared with any other known fossil

late quaternary sea level change in south africa abstract a late quaternary sea level curve for south africa is presented on the basis of new and published data from a range of sea level indicators and a variety of locations available evidence suggests that sea level in south africa broadly follows that described from the caribbean but that deviations occur during sea level highstands during the last interglaciation oxygen isotope stage 5 and the late holocene coastal emergence produced higher sea levels in south africa than those identified in the caribbean during the same time intervals this is tentatively ascribed to predicted lithospheric deformation in continental margin settings

orbital forcing of climate over south africa a 200 000 year rainfall record from the pretoria saltpan late pleistocene variations in rainfall in subtropical southern african are estimated from sediments preserved in the pretoria saltpan a 200000 year old closed basin crater lake on the interior plateau of south africa we show that south african summer rainfall covaried with changes in southern hemisphere summer insolation resulting from orbital precession as predicted by orbital precession geometry berger 1978 this south african record is out of phase with north african palaeomonsoon indices street and grove 1979 rossignol strick 1983 mcintyre et al 1989 the amplitude of the rainfall response to insolation forcing agrees with climate model estimates prell and kutzbach 1987 these results document the importance of direct orbital insolation forcing on both subtropical north and south african climate as well as the predicted antiphase sensitivity to precessional insolation forcing

caradocian land plant microfossils from libya the oldest paleontologically well dated spore tetrads and cuti clelike sheets of cells have been recovered from beds of caradoc mid ordovician age from boreholes in the murzuk murzuq and rhadames ghad mis basins of western libya these microfossils together with late llandovery early wenlock vascular plant megafossils lycophytes and psilophyton known from libya lead us to conclude that land plants including vascular plants probably had a long pre silurian record extending at least into the basal caradocian additonal evidence suggests that this record does not extend as far back as the earlier late cambrian dresbachian

a segment is not a monolith evidence from the howiesons poort of sibudu south africa segments from the howiesons poort of sibudu south africa can be separated into at least three populations based on quartz hornfels and dolerite rocks used for their production length breadth thickness and tip cross sectional areas are significantly different between segments made on the three rock types segments are not monoliths and they were not intended as a single tool type they were flexible enough to be mounted to shafts in a variety of ways several hafting strategies are evident including the use of different adhesive recipes most segments were probably parts of hunting weapons based on use trace analysis but weapon types varied quartz segments have standardized shapes short and deep perhaps because they were hafted as transverse arrowheads while hornfels and dolerite segments may on occasion also have been parts of projectiles the large dolerite segments could sometimes have served as parts of spearheads with two segments hafted back to back howiesons poort segment technology is sophisticated its makers appreciated distinct properties of rocks their flaking wear and impact possibilities further they recognized the best sizes and shapes for use with each kind of weapon they understood the qualities and applications of various adhesive recipes and they knew how to make a variety of hafts from materials that included bone and wood

ichnological signatures of shallow freshwater lakes in the glacial itarare group mafra formation upper carboniferous lower permian of parana basin s brazil abstract the upper carboniferous lower permian glacigenic deposits of the itarare group parana basin are widely known and cover an extensive area in the southern brazil these deposits consist of different arrangements of massive shales diamictites rhythmites and fine to medium grained sandstones with trough cross stratification five genetically distinct thickening locally coarsening upward successions of regular rhythmites can be distinguished in the mafra rio negro region santa catarina and parana states southern brazil representing the landward portion of an incised valley filled during deglaciation a low diversity invertebrate ichnofauna composed of a freshwater shallow burrow dominated suite and trackway dominated suite occurs in these rhythmites the freshwater shallow burrow dominated suite is composed of cochlichnus anguineus cruziana cf problematica gordia arcuata gordia marina hormosiroidea meandrica rusophycus cf carbonarius and treptichnus pollardi as well as undichnia consulca and intermittent rusophiciform traces it represents a mermia ichnocoenosis and occurs in the rhythmites of the upper sets commonly overlapped by d gouldi and d biformis in palimpsest preservation d gouldi and d biformis compose the trackway dominated suite which occur in all ichnofossiliferous paired mudstone siltstone of the basal sets of the rhythmite succession and in almost all of the upper sets it represents an atypical scoyenia ichnocoenosis and is generally preserved over microbially induced wrinkle structures the rhythmic deposition suggests distal underwater gravity flow deposits filling shallow lakes or ponds in depressed areas the siltstones deposited by melting currents and the mudstones by sediment fall out after the flux ceased the abundant wrinkle structures suggest quiet waters the overlying deposits bearing a brackish water ichnofauna and marine fossils suggest a coastal setting connected with the sea although atypical the occurrence of a scoyenia ichnocoenosis in almost all ichnofossiliferous rhythmite couplets preserved over wrinkle structures or overlapping mermia ichnocoenosis suggests that these shallow lakes were episodically dried up at least partially the present data allow interpreting the regular ichnofossiliferous rhythmites of the mafra formation as deposited in shallow lakes or ponds developed in outwash plains at the landward side of a fjord embayment during deglaciation

phanerozoic large igneous provinces lips heatt haline euxinic acidic thermal transgression episodes and mass extinctions abstract the phanerozoic consists of three mutually exclusive climate states icehouse greenhouse and hothouse the greenhouse is the default state representing 70 of the phanerozoic it is characterized by a weak thermal mode pole driven deep water formation with little or no continental sea ice and weakly oxic cool water sinking near the poles nitrogen limitation characterizes greenhouse oceans in which ammonium may be the dominant bioavailable form of nitrogen the steady state greenhouse default must be forced to produce either of the other two states continent continent collision produces the intense chemical weathering that draws down atmospheric co2 and results in the icehouse state that comprises 20 25 of the phanerozoic icehouses have ice caps in contact with the ocean that produce icebergs and foster sea ice formation sea ice formation fills the ocean with highly oxic phosphorus limited icewater except for a thin layer of warm surface water in the tropics of the 23 most conspicuous mass extinctions of the phanerozoic including the late ediacaran 4 are associated with ice volume related regressions and 3 are problematic we suggest that the other 16 mass extinctions occurred when greenhouse climate was forced to hothouse climate large igneous provinces lips can trigger the heatt haline euxinic acidic thermal transgression mechanism which can force greenhouse climate to a hothouse climate state the rapid voluminous co2 emissions of lips cause a series of events that result in very slow but pronounced haline mode circulation mid latitude driven deep water formation that produces warm saline bottom water at very dry hot subtropical and middle latitudes this water upwells at the poles causing warm and moist equable climate hothouse development promotes deep sea anoxia that is generated in concert with co2 buildup and warming the spread of anoxia favors reduced nitrogen over nitrate and limited iron dust curtails nitrogen fixation this leads to dominance of primary productivity by primitive green algae and or cyanobacteria progression to euxinia that reaches the photic zone severely curtails primary productivity via poisoning even as availability of usable nitrogen plummets the result is eukaryotic mass extinction we suggest that the 16 phanerozoic mass extinctions referred to above resulted at least in part from the heatt process evidence for this relationship at 11 of the most severe extinctions is convincing data sets for the other 5 are strongly suggestive of heatt related mass extinction but do not yet have enough documentation to reliably characterize them as heatt episodes

optical dating of holocene sediments from a variety of geomorphic settings using single grains of quartz this paper presents an improved method for the optical dating of holocene sediments from a variety of geomorphic settings we have measured the equivalent dose de in individual grains of quartz using green laser light for optical stimulation and have simulated the de distributions for multiple grain synthetic aliquots using the single grain data for 12 samples of known independent age we show that application of a minimum age model to the single grain and small 10 grain aliquot de data provides the most accurate estimate of the burial dose for nine of the samples examined 3 aeolian 5 fluvial and 1 marine the weighted mean de as obtained using the central age model gives rise to burial age overestimates of up to a factor of 10 for these nine samples whether single grains small aliquots or large 100 grain aliquots are used for the other three samples two aeolian and one fluvial application of either the minimum age model or the central age model to the single grain small aliquot and large aliquot de data yields burial ages in accord with the independent age control we infer that these three samples were well bleached at the time of deposition these results show that heterogeneous bleaching of the optical dating signal is commonplace in nature and that aeolian transport offers no guarantee that the sample will be well bleached at the time of deposition we also show that grains sensitive to infrared ir stimulation can give rise to low de values which will result in significant underestimation of the burial dose and hence of the age of deposition we demonstrate that use of a modified single aliquot regenerative dose protocol incorporating ir stimulation prior to green light stimulation deals effectively with contamination by ir sensitive grains we conclude that application of the modified protocol to single grains or small aliquots of quartz using the lowest de population to estimate the burial dose is the best means of obtaining reliable ages for holocene sediments from a wide range of depositional environments d 2003 elsevier b v all rights reserved

an experimental micromorphological investigation of bedding construction in the middle stone age of sibudu south africa abstract we conducted experiments to compare the micromorphological signatures of modern burnt sedge and grass bedding to laminated layers of carbonized material and phytoliths in middle stone age deposits at the shelter sibudu the experiments were designed to clarify the formation processes associated with the laminated layers and to investigate whether these previously identified layers of bedding were deliberately burned or not the results indicate that the laminated layers were most likely produced by human activity related to the construction maintenance and burning of bedding furthermore our experiments demonstrate that large volumes of vegetal material could have produced the relatively thin archaeological deposits of burnt bedding

criteria for identifying bone modification by termites in the fossil record three geographically dispersed middle and later stone age cave sites in south africa and a middle stone age cave site in ethiopia share a similar taphonomic signature that includes destruction of bones associated with variable forms of star shaped features clusters of microscopically visible sub parallel striations edge gnawing pits and etching of the bone surface similar traces preserved on plio pleistocene fauna are interpreted by different authors as the possible work of termites or ants considering that ambiguity exists in the interpretation of these traces and that there are no modern examples available for comparison we set out to create a reference collection of bones modified by southern african termites here we present the results of an actualistic experiment conducted with the harvester termite trinervitermes trinervoides sjostedt isoptera termitidae in the sterkfontein valley south africa results show that within six months all bones were approximately half covered with a dark surface residue had an etched surface appearance and recorded boreholes and destruction particularly of less dense elements and epiphyses star shaped marks edge gnawing and clusters of sub parallel striations on the periosteal surface were faint after six months but became clearly visible and more plentiful after 12 months a finding attributed to the termites being more active in austral autumn and spring this result demonstrates the pertinence of insect modification studies to our understanding of regional palaeoenvironment palaeoecology and palaeoclimate this experiment has demonstrated that t trinervoides can destroy bone in all stages of preservation favouring fresh thin cortical and spongy bone with meat and marrow the presence of appreciable quantities of calcium carbonate in termite mounds suggests that termites may be drawn to dolomitic cave sites and the calcium rich bones they contain to satisfy their mineral requirements they therefore have the potential to bias taxonomic and element representation minimum number of individuals and age profiles in a faunal assemblage and may account in part for the patchy preservation of faunal remains including hominins in fossil deposits and or the lack of bone artefacts at some middle stone age cave sites preserving long sequences of occupation

reconstructing the history of sediment deposition in caves a case study from wonderwerk cave south africa we applied cosmogenic isotope burial dating magnetostratigraphy and grain size distribution analysis to elucidate the history of the sedimentary sequence composed of fine quartz sands and silts of wonderwerk cave located on the southern edge of the kalahari desert south africa the source for the quartz sand is the kalahari sand dunes presently located 100 km to the north of the cave field observations and grain size analysis suggest a sediment transport scenario that includes eolian transport of kalahari sand abraded to a size of 70 100 m to the kuruman hills temporary storage on the hill slopes and valleys surrounding wonderwerk cave and later transport and deposition inside the cave our results suggest simple burial ages for sediments from both the front and back of the cave that range between 2 63 0 17 ma and 1 56 0 10 ma following initial exposure of 310 620 k y however 26 al 10 be ratios of 3 98 0 24 and 4 08 0 22 measured in a sand sample collected from the surface outside the cave may imply an initial burial signal equivalent to 0 78 0 15 ma thus reducing the possible age range of the buried samples to between 1 85 0 23 and 0 78 0 18 ma the paleomagnetic results for the front of the cave gave a polarity sequence of n r n n where n indicates normal polarity and r indicates reverse polarity this sequence can be correlated with both the older and younger cosmogenic burial age ranges the correlation suggests that in the cave front cosmogenic burial ages and the acquisition of stable remanent magnetization were not significantly affected by chemical and physical processes and that postburial production of cosmogenic isotopes was insignificant in contrast at the back of the cave the paleomagnetic polarity sequence of r n cannot be correlated with the cosmogenic burial ages since the temporal gap between the initial penetration of the sediment into the cave and the final acquisition of a stable remanent magnetization may have been long 10 5 yr and the single polarity transition can be correlated to any reverse normal transition that occurred during the quaternary this highlights the need for caution when cosmogenic burial ages and paleomagnetic sequences are compared the buried sediments in wonderwerk cave show similar grain size distributions to the fine sand sediment presently exposed at the surface in the vicinity of the cave furthermore calculated preburial 10 be concentrations for the buried sediment are similar to those measured in sediment outside the cave these similarities suggest that the environmental conditions and rates of geomorphic processes that persisted during sand deposition in wonderwerk cave during the late pliocene and early pleistocene may have been similar to those currently experienced in the southern kalahari the kuruman hills and the western ghaap plain these conditions favor the transport of fine grained quartz sand to the vicinity of the cave

fluid mineral equilibria in a hydrothermal system roosevelt hot springs utah the availability of fluids and drill cuttings from the active hydrothermal system at roosevelt hot springs allows a quantitative comparison between the observed and predicted alteration mineralogy calculated from fluid mineral equilibria relationships comparison of all wells and springs in the thermal area indicates a common reservoir source and geothermometer calculations predict its temperature to be higher 288 c 10 than the maximum measured temperature of 268 c the composition of the deep reservoir fluid was estimated from surface well samples allowing for steam loss gas release mineral precipitation and ground water mixing in the well bore this deep fluid is sodium chloride in character with approximately 9700 ppm dissolved solids a ph of 6 0 and gas partial pressures of o2 ranging from 10 32 to 10 35 atm co2 of 11 atm h2s of 0 020 atm and ch4 of 0 001 atm comparison of the alteration mineralogy from producing and nonproducing wells allowed delineation of an alteration pattern characteristic of the reservoir rock theoretical alteration mineral assemblages in equilibrium with the deep reservoir fluid between 150 and 300 c in the system na2o k2o cao mgo feo fe2o3 al2o3 h4sio4 h2o h2s co2 hcl were calculated minerals theoretically in equilibrium with the calculated reservoir fluid at 240 c include sericite k feldspar quartz chalcedony hematite magnetite and pyrite this assemblage corresponds with observed higher temperature 210 c alteration assemblage in the deeper parts of the producing wells the presence of montmorillonite and mixed layer clays with the above assemblage observed at temperatures 210 c corresponds with minerals predicted to be in equilibrium with the fluid below 240 c alteration minerals present in the reservoir rock that do not exhibit equilibrium with respect to the reservoir fluid include epidote anhydrite calcite and chlorite these may be products of an earlier hydrothermal event or processes such as boiling and mixing or a result of errors in the equilibrium calculations as a result of inadequate thermochemical data

quantification of climate and vegetation from southern african middle stone age sites an application using late pleistocene plant material from sibudu south africa abstract in southern africa numerous middle stone age msa sites document important steps in technological and behavioural development leading to significant changes in the lifeways of modern humans to assess whether these cultural changes and developments may be related to environmental changes we need to ascertain past environments to do this we apply a new quantitative method the gis based coexistence approach cagis on fossil plant material from the msa site sibudu kwazulu natal south africa previous qualitative environmental interpretations of the fossil fauna and flora of the site remain ambiguous because much of the material is anthropogenically introduced it is difficult to distinguish between the effects of natural changes in the local vegetation and behavioural changes of the people that inhabited the shelter cagis can be applied to such biased assemblages and seems to be an adequate method to directly quantify palaeoclimate and vegetation parameters at an archaeological site the cagis analysis shows that during the howiesons poort hp industry winters were slightly colder and drier than present whereas during summer temperatures and precipitation were similar to today post hp winters were drier and colder than present presumably colder than during the hp summer temperatures remained the same but summer precipitation decreased from the hp to post hp vegetation cover was less than today may be even less than during the hp the late msa was observably warmer than the older periods especially during winter at the same time summer precipitation slightly increased and vegetation became more dense but still remained generally open similar to today s anthropogenic landscape generally climatic changes are most pronouncedly reflected in winter temperature parameters especially in minimum winter temperatures and to a lesser extent by changes in summer precipitation the observed ecological trends seem to be affected mainly by variations through time in winter temperatures this refinement of interpretation was not discernible using previous methods for analysing the sibudu data

trace element distribution in an active hydrothermal system roosevelt hot springs thermal area utah abstract chemical interaction of thermal fluids with reservoir rock in the roosevelt hot springs thermal area utah has resulted in the development of characteristic trace element dispersion patterns multielement analyses of surface rock samples soil samples and drill cuttings from deep exploration wells provide a three dimensional perspective of chemical redistribution within this structurally controlled hot water geothermal system five distinctive elemental suites of chemical enrichment are recognized each characteristic of a particular combination of physical and chemical conditions within the geothermal system these are 1 concentrations of as sb be and hg associated with siliceous material at locations of liquid discharge fluid mixing or boiling 2 concentrations of mn ba w be cu co as sb and hg in manganese and iron oxide deposits 3 high concentrations of hg in argillized rock near fumaroles and lower concentrations in a broad diffuse halo surrounding the thermal center 4 concentrations of as in sulfides and li in silicate alteration minerals immediately surrounding high temperature fluid flow controlling fractures 5 deposits of caco 3 at depth where flashing of brine to steam has occurred due to pressure release the geochemical enrichments are not in general widespread pervasively developed zones of regular form and dimension as are typical in many ore forming hydrothermal systems as the geothermal system develops changes and eventually declines through time the chemical deposits are developed remobilized or superimposed upon each other thus preserving within the rocks a record of the history of the geothermal system recognition of trace element distribution patterns during the exploration of a geothermal system may aid definition of the present geometry and interpretation of the history of the system

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

the potential of paleozoic nonmarine trace fossils for paleoecological interpretations abstract many late paleozoic environments have been interpreted as marine because of the co occurrence of supposedly exclusively marine trace fossils beginning in the late ordovician however nonmarine trace fossil diversity increased throughout the paleozoic this diversification of nonmarine organisms and nonmarine trace fossils was especially prevalent in devonian and later times diversification of freshwater organisms is indicated by the large number of freshwater fish arthropods annelids and molluscs that had developed by the carboniferous in addition to diverse freshwater assemblages entirely terrestrial vertebrate and invertebrate ecosystems had developed by the devonian this rapid diversification of freshwater and terrestrial organisms is inherently linked to development and diversification of land plants and subsequent shedding of large quantities of organic detritus in nonmarine and marginal marine areas nearshore marine organisms and their larvae that are able to tolerate relatively short periods of lowered salinities will follow salt water wedges inland during times of reduced freshwater discharge similarly amphidromous marine organisms will migrate periodically inland into nonmarine environments undoubtedly both of these processes were active in the paleozoic however both processes are restricted to stream distributary channels interdistributary bays or estuaries therefore the presence of diverse trace fossil assemblages in association with floodplain deposits is interpreted to reflect true nonmarine adaptation and diversity conversely diverse trace fossil assemblages in association with stream distributary channel deposits interdistributary bay deposits or estuarine deposits may reflect migration of salt water wedges inland or migration of marine organisms into freshwater environments amphidromy or both

high resolution absolute dated indian monsoon record between 53 and 36 ka from xiaobailong cave southwestern china the oxygen isotopic record of stalagmite xbl 1 from southwestern china reveals millennial scale variability of the indian monsoon between 53 and 36 ka synchronous with changes in the east asian monsoon recorded at hulu cave and similar to dansgaard oeschger cycles recorded in greenland ice our record in general confirms the chronology of hulu cave if our correlations between greenland and the xiaobailong cave record are correct both the greenland ice sheet project 2 and greenland ice core project ss09sea chronologies are accurate within quoted errors a dry interval that we correlate with heinrich event 5 h5 and the greenland stadial preceding greenland interstadial 12 gis 12 is centered ca 48 0 ka and a shift to drier conditions correlated to the end of gis 12 is ca 43 5 ka overall the variability of the indian monsoon from xbl 1 data on millennial scales is similar to and correlated with high latitude ice core rec ords from the northern hemisphere however some indian monsoon characteristics more closely resemble but are anticorrelated with features in the antarctic record suggesting some link to climate of the high southern latitudes in addition to the clear link to the climate of the high northern latitudes

earliest modern humans in southern africa dated by isoleucine epimerization in ostrich eggshell the oldest anatomically modern human remains are beyond the range of radiocarbon dating and associated deposits lack material suitable for most other dating methods consequently age estimates for early human skeletal material and correlative stratigraphic horizons in southern africa are frequently based on paleoclimatic correlations to the deep sea record and extrapolated sedimentation rates both of which incorporate a number of untested assumptions here we focus on one substage of the middle stone age of southern africa the howiesons poort industry a distinctive culture stratigraphic marker in sequences south of the zambezi anatomically modern human skeletal material has been found associated with or even older than the howiesons poort layer in stratified deposits at border cave and klasies river main site we have dated or bracketed the howiesons poort horizon at border cave boomplaas cave and apollo 11 cave three stratified cave sites in southern africa based on the extent of isoleucine epimerization in associated ostrich eggshells we conclude that the howiesons poort lithic industry is bracketed by limiting dates of 56 and 80 ka and is most likely centered on 66 5 ka anatomically modern human remains in deeper levels are more than 100 ka old lending support to the hypothesis of an african origin for homo sapiens

early forest soils and their role in devonian global change a paleosol in the middle devonian aztec siltstone of victoria land antarctica is the most ancient known soil of well drained forest ecosystems clay enrichment and chemical weathering of subsurface horizons in this and other devonian forested paleosols culminate a long term increase initiated during the silurian from silurian into devonian time red clayey calcareous paleosols show a greater volume of roots and a concomitant decline in the density of animal burrows these trends parallel the decline in atmospheric carbon dioxide determined from isotopic records of pedogenic carbonate in these same paleosols the drawdown of carbon dioxide began well before the devonian appearance of coals large logs and diverse terrestrial plants and animals and it did not correlate with temporal variation in volcanic or metamorphic activity the early paleozoic greenhouse may have been curbed by the evolution of rhizospheres with an increased ratio of primary to secondary production and by more effective silicate weathering during silurian time

technical considerations and methodology for creating high resolution color corrected and georectified photomosaics of stratigraphic sections at archaeological sites abstract using a conventional off the shelf digital single lens reflex camera and flashes we were able to create high resolution panoramas of stratigraphic profiles ranging from a single meter to over 5 m in both height and width at the middle stone age site of pp5 6 at pinnacle point mossel bay south africa the final photomosaics are isoluminant rectilinear and have a pixel spatial resolution of 1 mm furthermore we systematically color corrected the raw imagery this process standardized the colors seen across the photomosaics while also creating reproducible and meaningful colors for relative colorimetric analysis between photomosiacs here we provide a detailed discussion about the creation and application of our photomosaics in the first part of the paper we examine the specific characteristics of modern digital single lens reflex dslr cameras and lenses that were important to us in developing our methodology we also provide a detailed discussion about how to reproduce the methodology in the field and to post process the imagery in the final section of the paper we give several examples to show how we apply our photomosaics within an empirical 3d gis database these examples are provided to show how photographic data can be integrated with other digitally captured data and used to study the relationships between the stratigraphic features seen in the photomosaics and the 3d distribution of excavated archaeological piece plots geochronological samples and other kinds of geological samples

arsenic in surface and up to 90 c ground waters in a basalt area n iceland processes controlling its mobility the concentrations of as in surface and up to 90 c ground waters in a tholeiite flood basalt area in n iceland lie in the range 0 5 g kg as the as content of ground waters increases on the whole with rising temperature arsenic is highly mobile in the basalt water environment of the study area an insignificant fraction of the as dissolved from the rock is taken up into secondary minerals arsenic is less mobile than b but considerably more mobile than na which has the highest mobility among the major aqueous components a significant fraction of the as in the basalt occurs in an easily soluble form the as hosted in the primary minerals is expected to be concentrated in the titano magnetite this mineral is stable in contact with both surface and ground waters and does not therefore supply as to the water explaining the difference in mobility between as and b aqueous as concentrations are a reflection of water rock ratios i e how much rock a given quantity of water has dissolved this ratio increases with increasing temperature and increasing residence time of the water in contact with the rock the distribution of as species has been calculated on the assumption of equilibrium at the redox potential retrieved from measurement of aqueous fe ii and fe iii concentrations these calculations indicate that pentavalent as is stable in surface waters and in ground waters with an in situ ph of 10 and would occur mostly as h 2 aso 4 and haso 2 4 in higher ph ground waters the concentrations of the arsenite species h 2 aso 3 is significant at equilibrium up to 65 of the total dissolved as

invertebrate trace fossils in semi arid to arid braided ephemeral river deposits of the mississippian middle member of the mauch chunk formation eastern pennsylvania usa abstract the rapid diversification of terrestrial ecosystems was initiated in the silurian and subsequently continued through the mississippian detailed collecting of the middle member of the mississippian mauch chunk formation in eastern pennsylvania has yielded a number of important vertebrate and invertebrate trace fossils indicating the presence of a significant terrestrial biotic diversity during the early carboniferous this report illustrates the diverse invertebrate trace fossil assemblage associated with the ephemeral river systems of the mauch chunk the mauch chunk invertebrate ichnoassemblage consists of backfilled burrows of deposit feeders both meniscate taenidium and non meniscate planolites that typically cross cut bedding arthropod trackways diplichnites diplopodichnus stiaria kouphichnium and stialla striated trails cruziana and resting traces rusophycus and surface or shallow subsurface grazing trails or burrows gordia tetrapod footprints mostly made by temnospondyl amphibians are also part of this ichnoassemblage the mauch chunk invertebrate ichnoassemblage corresponds well to the scoyenia ichnofacies in consisting of simple burrows trackways striate and bilobate trails and pits and simple meniscate burrows typically trace fossils of the scoyenia ichnofacies indicate opportunistic behaviors in subaerial environments that are temporarily or periodically inundated indeed the palaeoenvironmental setting of these traces is a semi arid to possibly arid braided ephemeral river system with extensive overbank deposits the invertebrate traces were developed both as infaunal burrows in the tops and within channel sandstones and as surface and grazing traces on in channel mudstone draped bedforms and in proximal overbank deposits the in channel mudstone draped bedforms display both vertebrate and invertebrate trace fossils the mauch chunk invertebrate ichnofossil assemblage resembles other devonian through triassic ichnoassemblages from ephemeral fluvial red beds confirming that the terrestrial invertebrate fauna had already fully colonized fluvial environments by mississippian time furthermore the development of the scoyenia ichnoguild in the mauch chunk formation in the form of abundant traces of deposit feeders of a shallow to intermediate depth infauna esp taenidium is unusually early when compared to the previously known palaeozoic record

optical dating in archaeology thirty years in retrospect and grand challenges for the future in 1982 when richard klein first became one of the editors of this journal the luminescence dating community was embarking on a new phase of exploratory research attention was turning from the use of thermoluminescence tl dating to estimate the time of last heating of archaeological objects such as pottery and burnt flint to the tl dating of unheated sediments that had been transported by wind and then deposited on the landscape this revolutionary development enabled the extension of tl dating to sedimentary deposits in a variety of environmental settings and to the multitude of archaeological sites that lack suitably heated artefacts in sediment dating the age of most interest is usually the time elapsed since grains of quartz or feldspar were last exposed to sunlight as the energy of the sun s rays is sufficient to evict electrons from their light sensitive traps these traps are steadily refilled after sediment deposition and the longer the grains remain buried the more tl they will emit when measured in 1985 huntley and colleagues proposed optical dating as a simpler and superior means of stimulating the light sensitive traps in quaternary sediments and this is now the principal luminescence based method of dating geological and archaeological deposits optical dating is an umbrella term for an armada of acronyms the most common in archaeological contexts being osl optically stimulated luminescence tt osl thermally transferred osl irsl infrared stimulated luminescence and pirir post infrared irsl all of these variants are founded on the same basic tenet measurement of a light sensitive signal to determine typically the last time that sediment grains were sun bleached but each approach has its virtues and vices in this paper we review this family of luminescence dating techniques and look back on 30 years of optical dating in archaeology some of the more interesting and important achievements are highlighted including the critical insights gained in the last two decades from osl measurements of individual grains of quartz we also look to the future of optical dating in archaeological contexts efforts to extend the age limits of optical dating to older hominin and archaeological sites will remain a key goal and understanding how archaeological sites of all ages form and evolve over time could be improved greatly by combining micromorphology analysis with optical dating of undisturbed intact sediments the latter poses a series of particularly formidable technical challenges but if the past is any guide to the future then we can expect optical dating to illuminate much more of human history before celebrating its golden jubilee

the distribution of arsenic iii and arsenic v in geothermal waters examples from the massif central of france the island of dominica in the leeward islands of the caribbean the valles caldera of new mexico u s a and southwest bulgaria abstract data for as iii as v and total as for various types of geothermal spring water are given the different species of as were separated at the time of sampling after filtration acidification and dilution where necessary using an anion exchange method total as as iii and as v were determined by flameless atomic absorption spectrometry the total as content ranges from 5 to 1800 g l 1 samples from dominica show evidence of different sulfur arsenic oxidation kinetics as iii being the major component 85 99 in fluids from deep levels of the geothermal reservoir and also 99 in oxidized waters of the acid sulfate type the bicarbonate spring water of the valles caldera new mexico contains more as iii than as v but there as v is the major component of the acid sulfate springs as iii proves to be the predominant form 60 100 in the warm alkaline waters from southwest bulgaria a selection of co 2 rich spring waters from the central massif france cezallier is analysed two groups are distinguished on the basis of major element chemistry and total as content oxidized forms are mainly encountered in the first group including a well sample containing 0 5 as iii the as iii content of the second group ranges from 10 to 70 these preliminary results indicate that the fluids directly related to hydrothermal systems contain mainly as iii whereas acid sulfate springs have a variable as iii content bicarbonate waters are generally enriched in oxidized as in the absence of springs or sinks within a geothermal region the total as concentration may display conservative properties but both as iii and as v may be reactive during mixing and cooling

biogeography and evolution of body size in marine plankton body size is a central feature of any organism reflecting its physiology ecology and evolutionary history marine microplankton are major contributors to the particulate inorganic carbonate foraminifers and coccolithophorids and opal flux radiolaria and diatoms in the ocean and hence size changes in these organisms can influence global biogeochemical cycles this paper is discussing abiotic influences on micro and macroecological size changes among major marine plankton groups linking these to evolutionary size changes during the neogene we review the patterns and outline the causes of size changes geographically and through time in coccolithophorids foraminifers and radiolarians the main feature of the neogene size record is a dramatic size increase in foraminifers a similarly dramatic reduction in the size range of coccolithophorids and highly variable size patterns in radiolarians we argue that the observed pattern is too complex to be explained by a simple common forcing and propose that speculations on the response of oceanic biomineralisation to global warming have to consider the scales at which marine plankton evolve

size matters preliminary results from an experimental approach to interpret middle stone age hearths abstract this paper reports on ten fire experiments and their significance for interpreting hearths from the middle stone age site sibudu kwazulu natal south africa the experiments were conducted on four different substrata and four wood taxa were used in the experiments four of the experiments consisted of a single fire while the other experiments consisted of multiple fires on top of each other the experimental fires produced hearth areas of 962 1 1661 9 cm and hearth depths of 3 12 cm hearth size and depth do not correlate hearth area seems to correlate with the fuel load used in a hearth and it is argued that this can be used in interpretations of fire use at an archaeological site nine hearths from the same layer at sibudu are used as examples and it is argued that variation in hearth area indicates variation in hearth use some hearths at sibudu were possibly only used once whereas others represent long term use and or repeated reloading of the same hearth

surface mercury geochemistry as a guide to volcanic vent structure and zones of high heat flow in the valley of ten thousand smokes katmai national park alaska abstract a reconnaissance survey of hg was designed to model the 1912 novarupta vent structure and delineate zones of near surface high heat flow statistical analysis of 294 regolith samples collected at 127 sites from fossil active fumaroles and relatively unaltered ash flow tuff and air fall ejecta indicates two hg sample populations one associated with fumarole deposits and the other corresponding to the relatively unaltered regolith measured hg concentrations range from 12 to 6913 ppb sample threshold upper limit of background hg concentrations fumarole deposits 351 ppb unaltered regolith 110 ppb and contrast sample value threshold determinations enable differentiation between relict and actively accumulating hg contents all significant hg anomalies contrast values 1 5 occur within novarupta basin high magnitude active hg2 enrichment was found on the turtle a dome like feature northeast of the novarupta extrusive dome the hg data coupled with available geologic and geophysical evidence suggest a shallow intrusion beneath the turtle results from two novarupta basin sample traverses do not support the presence of a near surface magma feeder dike connecting the proposed intrusion beneath the turtle with the novarupta dome based on the hg data the preferred vent model is one generated by collapse of supporting walls after the major eruptive phase into a cored out explosive vent collapse of vent walls is initiated along a series of deep extending faults which subsequently serve as migration pathways for hg to the surface the overall vent morphology is funnel like with subsidence concentrated in the narrow funnel center results of this study show that hg surveys can further constrain the morphology of the 1912 vent and aid in delineating zones of near surface high heat flow in this region

blombos cave southern cape south africa preliminary report on the 1992 1999 excavations of the middle stone age levels the later and middle stone age levels at blombos cave bbc were excavated over four field seasons between 1992 and 1999 here we report on the results from the middle stone age msa levels the taphonomy and depositional history of the msa levels is complex due to faulting folding and spalling careful observations during excavation have assisted in understanding some of these taphonomic and site formation processes microstratigraphic analysis currently in progress will add to this information the uppermost msa level the still bay phase contains high densities of bifacial points the fossile directeur of the still bay industry placing the still bay within the msa culture sequence has been problematic in the past because still bay assemblages are rarely found in situ and previous excavations were inadequately recorded however with the regional data discussed in the text the still bay can be securely placed before the howiesons poort dated at 65 70 ka flaked stone makes up the greatest proportion of all artefacts with the highest incidence of retouch and use of fine grained non local materials found in the still bay levels the ochre assemblage is remarkable for the mass of material compared to other msa sites finds uncommon in an msa context are two pieces of ochre from the still bay phase engraved with a geometric design a fragment of deliberately engraved bone also 28 shaped and polished bone tools recovered mainly from a phase just below the still bay blombos cave is the first site where well preserved faunal remains have been recovered in association with the still bay allowing for unique insights into human subsistence behaviour and palaeoenvironmental reconstruction large fish bones marine shells seals and dolphins attest to extensive exploitation of aquatic resources and a wide range of terrestrial animals were hunted and gathered the few human teeth recovered are heavily worn and damaged thus the issue of morphological modernity cannot be addressed the bbc findings are a useful adjunct to findings from other msa coastal sites in the southern cape especially klasies river kr and die kelders cave 1 dk1 uniquely bbc provides insights into human behaviour during a phase of the msa never before studied in detail

cemented ash as a receptacle or work surface for ochre powder production at sibudu south africa 58 000 years ago the white ash of sibudu hearths sometimes became cemented and when this was the case some of these crusts were used as work surfaces or receptacles particularly in occupations dating about 58 000 years ago substantial deposits of red and yellow ochre powder have been found on these crusts this suggests that the ochre was not associated with hearths for heat treatment because yellow ochre readily transforms to red even at low temperatures xrf readings suggest that the ochre used at the site derives from different geological sources micromorphological studies imply that phosphatization caused the cementation of the ashes in some hearths while gypsum growth hardened one of the hearths described here

tracking crystallinity in siliceous hot spring deposits siliceous hot spring deposits sinters entrap paleoenvironmentally significant components and are used as extreme environment analogs in the search for early earth and extraterrestrial life however sinters undergo a series of textural and mineralogical changes during diagenesis that can modify and overprint original environmental signals for ancient hydrothermal settings including those close to the dawn of life these transformations have long since occurred so that study of diagenetic processes and effects is best undertaken in much younger deposits still undergoing change three young sinters preserve the entire diagenetic sequence of silica phases from opal a to quartz the 6000 to 11 500 years bp 70 years sinter at steamboat springs nevada the 1600 1900 160 years bp opal mound sinter at roosevelt hot springs utah and the 456 35 years bp deposit at sinter island taupo volcanic zone new zealand provide an opportunity to track crystallographic mineralogic and morphologic transitions of sinter diagenesis using standard and new analytical approaches worldwide sinter forms from cooling alkali chloride waters as noncrystalline opal a transforming first into noncrystalline opal a ct then paracrystalline opal ct moganite paracrystalline opal c and eventually to microcrystalline quartz in this study these changes were identified by the novel and combined application of electron backscatter diffraction x ray powder diffraction and scanning electron and optical microscopy techniques we show that mineralogical changes precede morphological and accompanied crystallographic transformations during this modification silica particles grow and shrink several times from the micron to nano meter scales via dissolution reprecipitation and recrystallization and diagenesis follows the ostwald step rule all deposits followed nearly identical diagenetic pathways with time as the only variable in the march toward physicochemically stable quartz crystals diagenesis alters original environmental signatures trapped within sinters after five silica phase changes filamentous microfossils are modified but still remain recognizable within sinter from the opal mound and steamboat springs deposits and during the opal a to opal ct silica phase transformations at sinter island therefore delineating diagenetic components and how they affect sinters is necessary to accurately identify biosignals from ancient hot spring deposits

late ordovician glaciation initiated by early land plant evolution and punctuated by greenhouse mass extinctions abstractlate ordovician hirnantian glaciation indicated by periglacial paleosols tillites and glacial pavements in saharan africa has been attributed to advances in weathering and carbon sequestration due to evolution of early land plants in the same way that devonian permian glaciation has been attributed to evolution of forests and quaternary glaciations to evolution of grasslands two problems for carbon cycle explanations of this glaciation are an hirnantian co2 greenhouse estimated at 4035 ppmv from mass balance models and possibly related hirnantian mass extinctions this estimate of high co2 is a 10 m yr average here evaluated against high resolution sequences of paleosols that give estimates not only of co2 but also of paleoclimate and vegetation through the late ordovician katian paleosols of the eastern united states show increases in depth and in degree of carbon consumption and storage comparable with those preceding glaciation of the devonian permian and quaternary early thalloid l

earliest known uniramous arthropod the earliest known fully terrestrial animals are myriapods from the upper silurian of britain1 and unnamed myriapod like fossils have recently been reported from lower silurian marine deposits in wisconsin2 3 myriapod like burrows in upper ordovician soils from pennsylvania4 indicate the existence of earlier land animals here i report the discovery of a myriapod like fossil from marine deposits in the middle cambrian wheeler formation of utah that extends the record of myriapod like body fossils back by approxia mately 100 myr it thus represents the earliest known uniramous arthropod and may have special significance with respect to the ancestry of the terrestrial myriapods centipedes and millipedes and insects

high element mobility in 1 9 1 86 ga hydrothermal alteration zones bergslagen central sweden relationships with exhalative fe ore mineralizations abstract the 1 9 1 86 ga ensialic belt of western bergslagen sweden comprizes a 12 km thick felsic volcano sedimentary sequence intruded by syn volcanic granitic plutons and mafic dykes and sheets developed in a rifted continental setting regional low temperature alteration of the supracrustal sequence produced greenschist to low amphibolite facies mineral assemblages localized cross cutting zones of intense alteration are developed in felsic volcanics which have been affected by the regional alteration producing drastic changes in both mineralogy and chemistry these zones are found close to the hjulsjo granite granophyre intrusive complex most probably the heat source for the hydrothermal system and related to the exhalative sirsjoberg osjoberg fe oxide deposits the hjulsjo zones are subdivided into inner and outer zones based on differences in mineralogy and chemistry resulting from the variable intensity of alteration while the degree to which most elements are leached increases from the outer into the inner zones mg increases with alteration intensity and si and al stay unchanged although they were mobilized during alteration initially k rb fe and mn increase in the outer zones but are depleted in the inner zones rare earth elements ree are depleted with the light ree being more depleted than the heavy ree a pronounced negative eu anomaly is generally present the hydrothermal fluid was enriched in ore forming metals during alteration and leaching ree patterns of exhalative minerals indicate that the fe oxide deposits were derived from these hydrothermal fluids

hardly used habitats dearth and distribution of burrowing in paleozoic and mesozoic stream and lake deposits limited use of substrate ecospace by a meager infauna in streams and lakes is indicated by analysis of more than 10 000 observations of bioturbation in permian through jurassic freshwater deposits in contrast marine substrates have been inhabited and bioturbated since the cambrian colonization of freshwater substrates differed fundamentally from that of marine substrates bioturbation enhanced flux of dissolved materials across the sediment water interface was not operating until after the paleozoic in freshwater ecosystems

burned bone in the howieson s poort and post howieson s poort middle stone age deposits at sibudu south africa behavioral and taphonomic implications abstract despite a growing awareness of the wide range of information that can be provided by detailed analyses of burned bone from archaeological contexts such analyses are still relatively uncommon this paper focuses on the behavioral and taphonomic implications of burned bone from the middle stone age msa site of sibudu cave south africa reporting on the analysis of a large sample 377 000 fragments of bone recovered from the howieson s poort hp and post hp msa deposits at the site faunal remains were initially sorted into burning categories based on changes in color microscopic analyses focused on the optical properties of the bone matrix degree of preservation of the bone structure reflectance and fluorescence indicated that the color is a valid indicator of thermally altered bone in the sibudu assemblage the association of burned bone with hearths the intensity of burning damage and the sheer quantity of thermally altered bone suggests that the bone was not burned primarily as a result of natural fires we propose that the high incidence of burned bone primarily reflects two types of site maintenance activities first the discarding of bone into fire as a means of disposing of food waste as also argued by cain 2005 using burned animal bone to look at middle stone age occupation and behavior j archaeol sci 32 873 884 for a smaller sample of material from the post hp and late msa deposits at the site and second the incidental burning of bone on near the surface during the periodic burning of plant based bedding in considering the taphonomic implications of the burned bone we demonstrate that calcined bone is in fact more heavily fragmented than unburnt or moderately burned bone furthermore cortical preservation was negatively correlated with the intensity of burning damage which has implications for the study of surface modifications these results indicate the importance of conducting thorough taphonomic analyses prior to making comparisons between units that show differing degrees or intensities of burning damage

investigation of organic matter and biomarkers from diepkloof rock shelter south africa insights into middle stone age site usage and palaeoclimate the file associated with this record is under embargo until 36 months after publication in accordance with the publisher s self archiving policy the full text may be available through the publisher links provided above

intra basaltic soil formation sedimentary reworking and eodiagenetic k enrichment in the middle to upper ordovician dunn point formation of eastern canada a rare window into early palaeozoic surface and near surface conditions mafic flows of the middle to upper ordovician dunn point formation of eastern canada were deeply weathered under warm and relatively humid conditions before being buried by subsequent flows in the absence of superior plants and in the context of relatively low atmospheric carbon levels the soils developed alkaline groundwater conditions through mineral water interactions which resulted in an enhanced mobility of al relative to si in most palaeosols of that formation although the vegetation cover was volumetrically insignificant compared with that of subsequent geological times it was apparently producing very efficient chelates which for most palaeosols of the succession generated a well defined cheluviation pattern for not only al and fe but also and mainly ti which is typically immobile in modern soils the resulting soils developed an al fe ti depleted upper horizon that was enriched in si probably through periodic ground saturation long term climatic variations related to orbital cycles are inferred to have accounted for a second type of soil in the succession which contrasts with the former by showing a si depleted and less al fe ti depleted upper horizon some soil material was substantially reworked by surface runoff but such occurrences can be easily differentiated from in situ soil material in terms of texture structure and composition a thick overlying rhyolite flow is thought to be responsible for providing abundant k in solution which was incorporated in the underlying basalt palaeosols as exchangeable cations within a probably montmorillonitic clay precursor to the fe mg rich phengite that later developed during deep burial and orogenic compression

hydrothermal overprint on cenozoic sediments in the quadrilatero ferrifero of minas gerais implications for precious metals in cratonic terrains cenozoic sediments deposited in graben like basins in the quadrilatero ferrifero southern sao francisco craton brazil have anomalous contents of hg and sb two localities have been studied the topaz deposit of antonio pereira and the remains of the old opencast workings at cata preta one of the earliest au mines of minas gerais that dates back to about 1690 at cata preta a brecciated wad like rock exhibits geochemical fingerprints that point to fractionation of pt and pd from ag this metal fractionation reflected in the au ingots produced in the region genetically links cata preta to the near surface bonanza ore of serra pelada which formed as a result of a late cretaceous hydrothermal overprint in the amazon craton here we propose that anorogenic hydrothermal activity in cratonic terrains prepared the ground for the enrichment in precious metals that gave rise to two of the most important au rushes in brazilian history

still bay and serrated points from umhlatuzana rock shelter kwazulu natal south africa abstract umhlatuzana rock shelter is a long sequence middle and later stone age site in kwazulu natal south africa jonathan kaplan excavated the site and analysed the material in the 1980s as a rescue project for many years thereafter the collection remained untouched partly because of doubts raised about the stratigraphic integrity of the site using single grain osl dating we show that post depositional mixing of sediment was restricted to time specific small scale events the osl ages obtained for the howiesons poort and pre howiesons poort are comparable to those of other southern african sites with unambiguous howiesons poort and still bay industries based on morphological and other characteristics we reason that the still bay is represented at umhlatuzana and announce the presence of a serrated point assemblage closely associated in time with the still bay points

timing of millennial scale climate change in antarctica and greenland during the last glacial period a precise relative chronology for greenland and west antarctic paleotemperature is extended to 90 000 years ago based on correlation of atmospheric methane records from the greenland ice sheet project 2 and byrd ice cores over this period the onset of seven major millennial scale warmings in antarctica preceded the onset of greenland warmings by 1500 to 3000 years in general antarctic temperatures increased gradually while greenland temperatures were decreasing or constant and the termination of antarctic warming was apparently coincident with the onset of rapid warming in greenland this pattern provides further evidence for the operation of a bipolar see saw in air temperatures and an oceanic teleconnection between the hemispheres on millennial time scales

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

life on land in the precambrian microfossils have been discovered in cavity fill and replacement silica that occurs between chert breccia clasts in 1200 million year old paleokarst at the top of the mescal limestone central arizona and in 800 million year old paleokarst at the top of the beck spring dolomite southeastern california microbial communities on precambrian g550 million years ago land may have been extensive enough to affect weathering erosion sedimentation and geochemical processes

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

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

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr