effects of meteorological and hydrogeological factors on gross recharge percentage at unconfined sandy aquifers with an equatorial climate a thorough understanding of rainfall recharge processes and their controlling factors is essential for management of groundwater systems this study investigates the effects of various meteorological and hydrogeological factors on the gross recharge percentages the rainfall recharge relationships and the recharge threshold values for unconfined sandy aquifers under an equatorial climate among the meteorological factors investigated rainfall intensity was found to have the most significant impact on the gross recharge rate the effects of potential evaporation rate relative humidity and air temperature on the gross recharge percentage were significant when the vadose zone thickness is larger than 2 5 m the recharge threshold values were found to depend strongly on the vadose zone thickness the rainfall recharge relationships could generally be well defined by a normal log relationship the rainfall recharge relationships derived here are applicable to yield estimates of gross recharge percentages for unconfined sandy aquifers under an equatorial climate using rainfall intensity and vadose zone thickness as input variables in this study a theory was developed and validated to provide physical explanations for the observations based on the residence time of the percolated rainwater within the vadose zone among the soil hydraulic parameters tested porosity and saturated hydraulic conductivity were found to have the most pronounced effects on the gross recharge percentage utilizing the sensitivity results and the theory derived an approach was developed for extending the application of the derived rainfall recharge relationships to other sand textures the approach was found to be capable of producing rough and fast estimations of gross recharge percentage for other sand textures copyright 2007 john wiley sons ltd

thermoluminescence dating of a stillbay howiesons poort sequence at diepkloof rock shelter western cape south africa new excavations have been undertaken at diepkloof rock shelter drs south africa since 1999 it is one of the very few sites where howiesons poort and stillbay assemblages can be collected from the same archaeological sequence these middle stone age techno complexes are particularly interesting for their af nities with the much younger later stone age facies and their association with evidence for symbolic behaviour establishing their chronology is therefore particularly important for the understanding of the apparition and the evolution of the so called modern behaviours data already available suggest ages ranging from 55 to 80 ka for the howiesons poort and from 70 to 80 ka for the stillbay techno complexes in several south african sites the thermoluminescence dating undertaken at drs on 22 stone samples originating from the entire stratigraphic record indicates intervals starting 10 50 ka earlier for these techno complexes in this site possible caveats in the dating process are examined but to the best of our current knowledge must be rejected

luminescence dating at diepkloof rock shelter new dates from single grain quartz diepkloof rock shelter in south africa s western cape has been the subject of two different luminescence dating projects in recent years jacobs et al 2008 tribolo et al 2013 with somewhat divergent results this paper presents dating analysis of three additional samples from diepkloof as well as one sample each from kathu pan 6 and hollow rock shelter also in south africa these samples were collected in 1995 prior to the other two projects analysis of single grain quartz shows that the samples are near saturation conventional rejection criteria when applied to dose recovery data result in an underestimation of dose for high administered doses applying the fast ratio durcan and duller 2011 duller 2012 as a rejection criterion removes this underestimation and preferentially rejects grains from the samples with low equivalent dose values this makes the ages older than they would have been without this criterion age results are older than those presented by jacobs et al 2008 and slightly older or equivalent to those provided by tribolo et al 2013

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

heat treatment in the south african middle stone age temperature induced transformations of silcrete and their technological implications abstract it was recently found that silcrete raw material was heat treated during the south african middle stone age msa for altering its flaking properties this finding led to hypotheses about the implications for the msa hunter gatherers such as the cost of thermal treatment in terms of investment and firewood to date these hypotheses lack a solid basis for data on the thermal transformations of south african silcrete and hence the necessary heating procedure and heating environment is missing in order to produce such data we conducted an experimental study within the framework of the diepkloof project this work is based on the petrographic mineralogical and structural analysis of south african silcrete from the west coast and its thermal transformations our results shed light on the nature of these transformations the ideal heating temperatures and the tolerated heating speed the processes occurring in silcrete are comparable to flint i e the loss of chemically bound water and the formation of new si o si bonds but their intensity is less pronounced effective heating temperatures are significantly higher than for flint and the heating speed tolerated by south african silcrete is relatively fast these findings imply that silcrete heat treatment cannot be directly compared with flint heat treatment unlike flint heating silcrete does not require the setup of a dedicated heating environment and may have been performed in the same time as other fire related activities this would represent only a minor supplementary investment in time and firewood these results have broad implications for the discussion about technological evolution and the acquisition of specialised knowledge in the msa

relationship between modern rainfall variability cave dripwater and stalagmite geochemistry in guam usa 1 modern rainwater cave dripwater and cave stalagmite geochemical time series from a cave in guam 13 38 n 144 53 e are used to better understand how changes in cave stalagmite geochemistry relate to aboveground changes in rainfall at a tropical location a scientific field team based in guam collects monthly samples from multiple sites for geochemical analyses at a cave and aboveground rainfall from a nearby location we compute a transfer function between rainfall amount and oxygen isotopic composition 18o of a decrease increase of 0 94 0 3 m year for every 1 increase decrease in rainfall 18o based on data extracted from the international atomic energy agency iaea global networks of isotopes in precipitation gnip database and from data generated in this study dripwater 18o and mg ca ratios show annual cyclicity at some but not all sites accentuating the complex nature of cave hydrology a stalagmite 18o record for the last 160 years indicates the existence of droughts of decadal length when rainfall is estimated to be 0 65 0 3 m year less than average conditions this estimate of rainfall reduction most likely refers to wet season months as these months preferentially contribute to groundwater recharge the proxy based climate record at guam provides new evidence highlighting how a rainy site in the western pacific warm pool today can experience considerable changes in rainfall on decadal timescales

late pleistocene precipitation δ18o interpolated across the global landmass global water cycles ecosystem assemblages and weathering rates were impacted by the 4 c of global warming that took place over the course of the last glacial termination fossil groundwaters can be useful indicators of late pleistocene precipitation isotope compositions which in turn can help to test hypotheses about the drivers and impacts of glacial interglacial climate changes here a global catalog of 126 fossil groundwater records is used to interpolate late pleistocene precipitation 18o across the global landmass the interpolated data show that extratropical late pleistocene terrestrial precipitation was near uniformly depleted in 18o relative to the late holocene by contrast tropical 18o responses to deglacial warming diverged late pleistocene 18o was higher than modern across india and south china but lower than modern throughout much of northern and southern africa groundwaters that recharged beneath large northern hemisphere ice sheets have different holocene pleistocene 18o relationships than paleowaters that recharged subaerially potentially aiding reconstructions of englacial transport in paleo ice sheets global terrestrial late pleistocene precipitation 18o maps may help to determine 3 d groundwater age distributions constrain pleistocene mammal movements and better understand glacial climate dynamics

selective recharge and isotopic composition of shallow groundwater within temperate epigenic carbonate aquifers summary this paper considers the variation of 18o and 2h vsmow in precipitation and shallow groundwater from carbonate aquifers that lend insight into the source and timing of recharge within temperate epigenic karst the shallow groundwater collected during 2010 and 2011 at stream cave sc and natural bridge caverns nbc represent one input to and the primary output from the redmond creek karst aquifer in the cumberland plateau of southeast kentucky respectively these data are compared with the isotopic composition of concurrent samples of precipitation from the same watershed that covers some 1900 ha values of 18o and 2h at sc and nbc are statistically similar and cluster at the midpoint of the local meteoric water line these values remain surprisingly constant despite seasonal changes in temperature regimens and discharge samples in 2012 from regional springs that include redmond creek are more depleted in the heavier isotope and similarly stable despite coming from aquifers of a range of sizes and physical characteristics applying a priestly taylor model for daily values of potential evapotranspiration only 43 of the 1 10 m of precipitation in the 2010 2011 dataset remains as potential recharge primarily during cooler months with lower solar insolation weighting 18o and 2h values of precipitation by potential recharge creates a better match with the isotopic composition of shallow groundwater than by weighting by precipitation amount the isotopic composition and deuterium excess of precipitation samples are directly and inversely proportional to temperature respectively deuterium excess in this study and displays intra and inter annual variation that ranges from a minimum of 11 1 to a maximum of 29 5 that demonstrate the higher than average deuterium excess in greater appalachia and the shifting latitude of moisture sources including a significant winter component of re evaporated continental moisture

first molecular identification of a hafting adhesive in the late howiesons poort at diepkloof rock shelter western cape south africa abstract the hafting of tools using adhesive is one of the innovative features that characterizes the southern african middle stone age this technology has mainstream implications but remains insufficiently documented largely due to unequal organic preservation and non adapted analytical procedures a notable exception is provided by the recent results from the site of sibudu lombard 2006 wadley et al 2009 the excavation at diepkloof rock shelter has revealed several lithic artifacts with a black residue distributed over their surface their stratigraphic distribution reveals a strict association with the howiesons poort hp and suggests a close relationship between the appearance of hafting adhesive and the appearance of blades and geometric backed tools macroscopic and microscopic observations attest to a hafting that was exclusively lateralized and preliminary use wear analysis igreja and porraz in this issue supports the hypothesis that hafted tools were mostly integrated within daily domestic activities in this study we focused specifically on a chemical study of a thick black residue found on a quartz flake attributable to the late phase of the hp we determine for the first time in a msa context the nature of the compound adhesive and reconstruct a picture of the multilevel operations and interactions that comprise the process of hafting the molecular analysis attests to the exploitation of podocarpus elongatus yellowwood collected in the form of a resin that was naturally dried or heated at a low temperature and possibly mixed with fragmented bone and quartz grains compared to sibudu where ochre additive is documented the hafting technology at diepkloof introduces another level of variability within the hp tradition and suggests the existence of regional expressions and adaptations

the transfer of seasonal isotopic variability between precipitation and drip water at eight caves in the monsoon regions of china abstract this study presents new stable isotope data for precipitation 18op and drip water 18od from eight cave sites in the monsoon regions of china mrc with monthly to bi monthly sampling intervals from may 2011 to april 2014 to investigate the regional scale climate forcing on 18op and how the isotopic signals are transmitted to various drip sites the monthly 18op values show negative correlation with surface air temperature at all the cave sites except shihua cave which is opposite to that expected from the temperature effect in addition although the monthly 18op values are negatively correlated with precipitation at all the cave sites only three sites are significant at the 95 level these indicate that due to the various vapor sources a large portion of variability in 18op in the mrc cannot be explained simply by either temperature or precipitation alone all the thirty four drip sites are classified into three types based on the 18od variability about 82 of them are static drips with little discernable variation in 18od through the whole study period but the drip rates of these drips are not necessary constant their discharge modes are site specific and the oxygen isotopic composition of the stalagmites growing from them may record the average of multi year climatic signals which are modulated by the seasonality of recharge and potential effects of evaporation and in some cases infiltration from large rainfall events about 12 of the thirty four drip sites are seasonal drips although the amplitude of 18od is narrower than that of 18op the monthly response of 18od to coeval precipitation is not completely damped and some of them follow the seasonal trend of 18op very well these drips may be mainly recharged by present day precipitation mixing with some stored water thus the stalagmites growing under them may record portions of the seasonal climatic signals embedded in 18op about 6 of the thirty four drip sites are medium variability drips with constant and relatively low 18od values in the wet season but with variable and relatively high 18od values in the dry season reflecting flow switching in the karst or evaporation inside the cave

nature and significance of the howiesons poort to post howiesons poort transition at klein kliphuis rockshelter south africa abstract this paper considers the transition from howiesons poort to post howiesons poort technologies at the rock shelter site of klein kliphuis south africa the transition at this site is shown to be gradual with incremental changes in material selection and in the size and shapes of flakes and cores implements which appear to blend characteristics of those distinctive of the earlier and later industries appear briefly at the mid point of the transition the results suggest that there is unlikely to have been an occupational hiatus between the howiesons poort and post howiesons poort explanations for the howiesons poort phrased in terms of population expansion and contraction are also difficult to support technological changes at this time may relate to environmental variation though the limited nature of terrestrial archives documenting changes in resource productivity necessitate that any such suggestion be made with caution

refitting evidence for the stratigraphic integrity of the kudu koppie early to middle stone age site northern limpopo province south africa abstract stone age sites that demonstrate long sequences of occupation that span the earlier through to the later stone age are uncommon in southern africa the site of kudu koppie in the mapungubwe national park of limpopo province south africa has evidence for extended and intense occupation by prehistoric populations in the context of a talus slope deposit adjacent to the koppie itself this paper describes the use of refitting of late earlier stone age esa and middle stone age msa lithics to address issues of stratigraphic integrity and taphonomy in a slope deposit context specifically it is shown that approximately 80 of all refits fall with a vertical separation of between 0 and 10 cm it is concluded that lithics associated with kudu koppie have not been greatly affected by post depositional disturbances and therefore the material represents the general discard patterns of groups occupying the site between the late esa and msa periods as such this study provides additional evidence for earlier interpretations of the stratigraphic integrity of archaeological deposits at the site

large kinetic isotope effects in modern speleothems the application of stable isotopes in speleothem records requires an understanding of the extent to which speleothem calcite isotopic compositions refl ect the compositions of the cave waters from which they precipitate to test for equilibrium precipitation modern speleothem calcite was grown on glass plates so that the carbon and oxygen isotope composition of the calcite and the water from which it precipitated could be directly compared the plates were placed on the tops of three actively growing stalagmites that occupy a 1 m 2 area in harrison s cave barbados west indies only some of the plate 13 c values and none of the plate 18 o values correspond to equilibrium values indicating signifi cant kinetic isotope effects during speleothem calcite growth we investigate herein mechanisms that may account for the kinetic isotope effects on each plate speleothem calcite was deposited with distinct 18 o and 13 c compositions that increase progressively away from the growth axis with up to 6 6 13 c and 1 7 18 o enrichments the positive 13 c

evidence for 800years of north atlantic multi decadal variability from a puerto rican speleothem abstract the long term behavior of the tropical atlantic ocean atmospheric system prior to the 20th century is not well characterized due to a lack of high resolution proxy records to extend the short instrumental record here we present the first reconstruction of rainfall variability for the western tropical atlantic that spans the past 8 centuries and is derived from the 18o of speleothem calcite the 18o of speleothem calcite at this puerto rican location varies primarily in response to changes in the amount of summer time precipitation the speleothem documents multi decadal to centennial length oscillations in 18o that point to large variations in rainfall that have not been manifest in the short instrumental period since ad 1850 variations in 18o have tracked shifts in the atlantic multidecadal oscillation amo we tentatively suggest that the speleothem 18o based rainfall record from puerto rico extends the history of the amo to the 12th century

a method for estimating edge length from flake dimensions use and implications for technological change in the southern african msa abstract this paper presents a method for estimating edge length from flake dimensions comparison of estimated values with data from measured flake edges demonstrates the robusticity of the method building on the work of braun braun d r 2005 examining flake production strategies examples from the middle paleolithic of southwest asia lithic technology 30 107 125 braun d r harris j w k 2003 technological developments in the oldowan of koobi fora innovative techniques of artifact analysis and new interpretations of oldowan behavior in mora r de la torre i eds oldowan rather more than smashing stones treballs d arqueologia 9 pp 132 144 this estimate is used to generate an edge length to mass value for complete flakes taken to be a proxy for flaking efficiency it is shown that this value is useful in tracking the onset variability and decline of a well known technological phase the howiesons poort of south africa the results suggest that the howiesons poort was a time in which flaking efficiency was emphasised furthermore comparison of upper limits of edge to mass values for different raw materials may provide an insight into changes in raw material selection

orbital scale nonlinear response of east asian summer monsoon to its potential driving forces in the late quaternary we conducted a statistical study to characterize the nonlinear response of the east asian summer monsoon easm to its potential forcing factors over the last 260 ka on orbital timescales we find that both variation in solar insolation and global ice volume were responsible for the nonlinear forcing of orbital scale monsoonal variations accounting for 80 of the total variance specifically easm records with dominated precession variance exhibit a more sensitive response to changes in solar insolation during intervals of enhanced monsoon strength but are less sensitive during intervals of reduced monsoon strength in the case of global ice volume with 100 ka variance this difference is not one of sensitivity but rather a difference in baseline conditions such as the relative areas of land and sea which affected the land sea thermal gradient we therefore suggest that easm records with dominated precession variance recorded the signal of a shift in the location of the inter tropical convergence zone and the associated changes in the incidence of torrential rainfall while for proxies with dominated 100 ka variance it recorded changes in the land sea thermal gradient via its effects on non torrential precipitation

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

the howiesons poort and msa iii at klasies river main site cave 1a we present the results of a technological analysis of the howiesons poort and msa iii lithic artifacts from cave 1a at klasies river we studied most of the debitage and retouched pieces from deacon s excavations about 3000 pieces and all the cores and retouched pieces from three layers of singer and wymer excavations 640 pieces our analysis shows 1 that hp blade production was based on the use of marginal percussion by soft stone hammer as at rose cottage 2 that impact scars at klasies rose cottage and sibudu indicate that the backed pieces were hafted in two differentways and 3 that the hp backed pieces were an innovativeway of hafting spear tips but are not clear evidence of the invention of bows and arrows we document the gradual evolution of debitage techniques within the hp sequence with progressive abandonment of the hp technological style very similar trends occur in the upper part of the hp sequence at rose cottage the similarity in temporal trends between sites separated by more than 600 km has significant implications for the disappearance of the hp industry we suggest that the disappearance of the hp was not due to a phenomenon of population contraction and isolation that caused the collapse of social networks the internal evolution and parallel process of change documented at klasies and rose cottage speak against a collapse of social systems and are associated with evidence of environmental and subsistence changes at the transition mis 4 3

a middle stone age paleoscape near the pinnacle point caves vleesbaai south africa abstract open air middle stone age msa contexts in southern africa have received relatively little research attention compared to caves rock shelters msa caves rock shelters can provide long sequences of msa behaviors dominated by residential activities in circumscribed contexts but most procurement activities occurred on the landscape in uncircumscribed space we have a limited understanding of these activities at present making studies of open air sites crucial to alleviate this bias the south african coast paleoclimate paleoenvironment paleoecology paleoanthropology sacp4 project expanded its research scope to include msa archaeology from open air contexts we report on a series of msa open air assemblages that are exposed on ancient land surfaces suggestive of intact paleosols at vleesbaai and visbaai south africa importantly these sites occur in close proximity to the long cave rock shelter sequences at pinnacle point this presents the novel potential to study evidence of msa behavior in closed and open settings where their proximity to each other approximates the typical hunter gatherer daily foraging radius documented in ethnography we present a fabric and technological analysis of msa stone tool assemblages from three areas analysis of total station piece plotting of artifact bearing plunge suggests that the lithic assemblages have undergone limited post depositional disturbance the technological analysis and exploratory comparisons between these open air assemblages and msa cave and rock shelter contexts at pinnacle point cave 13b and 9 and cape st blaize cave suggest that the quartzite artifacts from vleesbaai were procured from locally available sources and may have been field processed there before being transported elsewhere perhaps to the caves rock shelters further the analysis suggests a dichotomous pattern of retouched tool discard where quartzite tools are discarded similarly across the landscape in contrast non quartzite tools may have been made primarily at the cave sites and discarded or lost more frequently on the landscape

combined records from a stalagmite from barbados and from lake sediments in haiti reveal variable seasonality in the caribbean between 6 7 and 3 ka bp abstract the growth of a well dated stalagmite from barbados records high infiltration rates into the karst aquifer and hence increased rainfall intensity between 6 7 and 3 ka bp in agreement with records from lake miragoane haiti hodell et al 1991 reconstruction of the caribbean climate change over the past 10 500 years nature 352 790 793 mainly reflecting the insolation maximum of the northern hemisphere both the lake record and the stable isotope record of the stalagmite reveal additional centennial variability of recharge high oxygen isotope values in stalagmite calcite corresponding to reduced recharge are synchronous with periods of lower stable isotope values recorded in lake miragoane ostracods previously attributed to enhanced precipitation accordingly periods of increased recharge in barbados correspond to 18o enriched isotope values of ostracods which were attributed to higher evaporation precipitation ratios in the lakes we ascribe this apparent discrepancy to changes in seasonality i e winter periods of reduced temperature and relative humidity following summer months of increased precipitation at present such climate conditions occur during periods of enhanced northern atlantic oscillation nao if enhanced seasonality is a consequence of a nao situation the apparent discrepancy of high isotope values in lakes previously attributed to droughts can be reconciled with lower winter temperatures in the lakes further the correlation of solar intensity derived from 14c and 10be with the isotopic signals recorded in the lacustrine sediments suggests a solar forcing of the nao during the mid holocene

patterns of temporal scaling of groundwater level fluctuation summary we studied the fractal scaling behavior of groundwater level fluctuation for various types of aquifers in puerto rico using the methods of 1 detrended fluctuation analysis dfa to examine the monofractality and 2 wavelet transform maximum modulus wtmm to analyze the multifractality the dfa results show that fractals exist in groundwater fluctuations of all the aquifers with scaling patterns that are anti persistent 1 1 5 1 62 0 07 4 wells the multifractal analysis confirmed the need to characterize these highly complex processes with multifractality which originated from the stochastic distribution of the irregularly shaped fluctuations the singularity spectra of the fluctuation processes in each well were site specific we found a general elevational effect with smaller fractal scaling coefficients in the shallower wells except for the northern karst aquifer upper system high spatial variability of fractal scaling of groundwater level fluctuations in the karst aquifer is due to the coupled effects of anthropogenic perturbations precipitation elevation and particularly the high heterogeneous hydrogeological conditions

geoarchaeological investigations at diepkloof rock shelter western cape south africa abstract the sedimentary sequence at diepkloof rock shelter formed through a complex interaction of depositional and post depositional processes and was variously influenced by biogenic geogenic and anthropogenic agents here we present the results of a micromorphological study of the sediments at diepkloof focusing in particular on the numerous anthropogenic inputs and modifications recorded within the sequence by applying the microfacies concept we were able to identify hearth burning and maintenance bedding construction and burning and surface modification by trampling as major processes that contributed to the formation of the site the human activities recorded within the sediments show a marked change throughout the sequence implying a shift in the use of the site over time the present study also provides a context for evaluating other classes of artifacts and data collected from the site

oxygen isotopic fractionation between drip water and speleothem calcite a 10 year monitoring study central texas usa abstract speleothem 18o values can serve as a paleoclimate proxy yielding information about past temperature and rainfall an accurate determination of the equilibrium calcite water oxygen isotopic fractionation factor and an assessment of kinetic isotopic fractionation are required for interpretation of speleothem 18o data in this study 18o values were measured for calcite deposited on artificial substrates at four sites in two central texas caves monitored for over 10 years the results are used to evaluate the equilibrium isotopic fractionation factor and the impact of climatic and hydrologic conditions on kinetic isotopic fractionation the 18o values of calcite from the four sites ranged from 24 8 to 26 7 v smow and associated drip water values ranged from 4 6 to 3 9 a comparison of predicted equilibrium calcite 18o values calculated using a commonly used isotopic fractionation factor with measured values indicates that 94 of the calcite samples are not in oxygen isotopic equilibrium with respect to their associated drip water the departure from oxygen isotopic equilibrium expressed as 18occ e ranges from 0 7 to 1 4 three of the four drip sites yield similar linear relationships between 18occ e and water temperature tw and can be collectively expressed as 18occ e 0 3tw 4 7 r2 0 56 n 93 therefore calcite deposited during time periods of lower tw lower cave air co2 concentration and faster calcite deposition rates have 18o values closer to equilibrium this contradicts conceptual models which predict that a faster calcite deposition rate leads to a larger departure of calcite 18o from equilibrium if slower calcite deposition indeed facilitates equilibrium fractionation i e 18occ e 0 then the results of this study support a larger than commonly accepted value for the equilibrium calcite water oxygen isotopic fractionation factor adopting a larger published value for the fractionation factor yields negative 18occ e values of up to 2 4 these negative values cannot be explained by existing kinetic fractionation models alternatively they may reflect the trapping of a calcite surface layer with a lower 18o value than that of calcite in isotopic equilibrium with ambient water the relationship between deposition rates and 18occ e for this study is consistent with the same relationship using data for synthetic calcite from the literature this relationship indicates a 0 8 shift of calcite 18o for every ten fold increase in deposition rate at 5 to 25 c and a ph of 8 3 the significant kinetic fractionation observed in this study warrant consideration in applying measured speleothem calcite 18o values to interpret past climate conditions

early use of pressure flaking on lithic artifacts at blombos cave south africa pressure flaking has been considered to be an upper paleolithic innovation dating to 20 000 years ago 20 ka replication experiments show that pressure flaking best explains the morphology of lithic artifacts recovered from the 75 ka middle stone age levels at blombos cave south africa the technique was used during the final shaping of still bay bifacial points made on heat treated silcrete application of this innovative technique allowed for a high degree of control during the detachment of individual flakes resulting in thinner narrower and sharper tips on bifacial points this technology may have been first invented and used sporadically in africa before its later widespread adoption

klipdrift shelter southern cape south africa preliminary report on the howiesons poort layers abstract surveys for archaeological sites in the de hoop nature reserve southern cape south africa resulted in the discovery of a cave complex comprising two locations klipdrift cave and klipdrift shelter excavations commenced in 2010 with later stone age deposits initially being recovered at the former site and middle stone age deposits at the latter the lithic component at klipdrift shelter is consistent with the howiesons poort a technological complex recorded at a number of archaeological sites in southern africa the age for these deposits at klipdrift shelter obtained by single grain optically stimulated luminescence spans the period 65 5 4 8 ka to 59 4 4 6 ka controlled and accurate excavations of the discrete layers have resulted in the recovery of a hominin molar marine shells terrestrial fauna floral remains organic materials hearths lithics ochre and ostrich eggshell more than 95 pieces of the latter distributed across the layers are engraved with diverse abstract patterns the preliminary results from klipdrift shelter presented in this report provide new insights into the howiesons poort in this sub region and contribute further to ongoing knowledge about the complex behaviours of early homo sapiens in southern africa excavations at the klipdrift complex will continue in the future

human adaptation strategies to abrupt climate change in puerto rico ca 3 5 ka the connection between climatic change and social response is complex because change articulates a number of inter related factors human decisions are filtered by social buffers including social

middle stone age pieces esquillees from sibudu cave south africa an initial micro residue study abstract in this paper i present the results of a micro residue study conducted on ten pieces esquillees scaled pieces from sibudu cave south africa these artefacts are associated with the howiesons poort industry 61 7 and 64 7 ka years ago at sibudu representing part of the later phase of the middle stone age until now it was unclear on what these pieces were used and whether they were functional previous experimental use wear work tentatively pointed towards bone processing however replication work on stone tool production technology suggests that pieces esquillees are merely the by end product of bipolar knapping i used residue analysis on the sibudu artefacts because this alternative method has the potential to identify if they were used and if so illuminate the specific materials the pieces were used on although the sample is small all the pieces esquillees reveal a clear animal processing signal there are some bone deposits on the utilised edges that may substantiate bone processing or perhaps a bone hammer was used with them but additional study including later stone age artefacts is needed to assess the feasibility of these observations it remains possible that the artefacts are core reduced pieces that were subsequently used as tools or simply knapped with a bone hammer

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

new knapping methods in the howiesons poort at sibudu kwazulu natal south africa abstract the lithic technology study of layer grey sand at sibudu reveals a large number of cores on flakes varying knapping methods of core reduction are presented here most of the core reduction techniques can be attributed to bladelet or small flake production also we point to a new type of blade production from prismatic cores revealed by the study of debitage these innovative knapping methods demonstrate the technological variability associated with howiesons poort lithic assemblages

estimating recharge thresholds in tropical karst island aquifers barbados puerto rico and guam the hydrology and geochemistry of groundwater in tropical island aquifers such as barbados guam and puerto rico are significantly influenced by tropical climatic conditions recharge to these aquifers is the product of regional and local climate patterns that control rainfall oxygen isotopes can be used to estimate the amount and timing of recharge on these islands because seasonal fluctuations of rainwater oxygen isotopic compositions are related to the amount of rainfall the karst aquifers on barbados guam and puerto rico have similar rainwater and groundwater oxygen isotopic compositions comparison of groundwater and rainwater oxygen isotopic compositions in the three aquifers indicates that 1 recharge occurs by rapid infiltration with little evaporation prior to recharge and 2 recharge is associated with similar monthly rainfall thresholds of 190 200 mm these rainfall thresholds are remarkably similar for three aquifers in different geographic locations differences between the spatial variations of groundwater oxygen isotopic compositions on barbados and puerto rico can be attributed to the more complex groundwater flow system on puerto rico the surprising similarities of hydrologic conditions under which recharge will take place can be attributed to similarities in climate and geologic conditions such as soils and limestone bedrock that exist on the three islands we therefore speculate that similar recharge rainfall thresholds may be observed in other tropical karst aquifers q 2003 elsevier science b v all rights reserved

an assessment of hydrogeological parameters on the karstic island of dugi otok croatia summary extensive explorations have been performed in the northern part of the island of dugi otok in the adriatic sea croatia with the purpose of extraction of fresh and or brackish water the island is predominantly composed of karstified carbonate rocks of the cretaceous age the explorations included geological and hydrogeological mapping of the area geophysical surveys by means of the geoelectric tomography method electrical resistivity sounding and surface seismic refraction exploratory core drilling hydrochemical in situ and laboratory explorations and the pumping test with the calculation of rock mass parameters based on the obtained results it was concluded that it is possible to exploit the groundwater with a pumping quantity of 5 l s without intrusion of salt water into the fresh water lens choosing a pumping regime based on the parameters of the aquifer rock mass hydraulic conductivity order of magnitude 10 4 10 6 m s and knowing the parameters of the well as well as the tidal efficiency should reduce the possibility of intrusion to the minimum because of the systematic quality of the performed explorations and obtained results the island of dugi otok can serve as a typical example for such kinds of exploration works on other karstic islands hydrogeological composition behaves partly according to ghyben herzberg s law but because of the nature of the karstic hydrogeological system such a statement needs to be accepted approximately because of the highly complicated relationships

recharge and aquifer response northern guam lens aquifer guam mariana islands abstract the northern guam lens aquifer is an island karst aquifer in uplifted young highly conductive limestone calculations of recharge based on differences between daily rainfall and daily pan evaporation suggest that the maximum annual mass of water delivered to the freshwater lens is about 67 of mean annual rainfall hydrographs of daily well level responses plotted against daily rainfall indicate that the rate at which water is delivered to the lens is a function of rainfall intensity and the relative saturation of the vadose zone together these variables determine the degree to which stormwater is shunted into fast flow through preferred pathways that bypass the bedrock matrix rather than percolating slowly through the bedrock matrix data from the 40 year interval from 1956 to 1995 show that some 17 of rainfall on northern guam arrives in small amounts 5 0 cm day which tend to promote fast flow at the expense of percolation rapid recovery of the water table from rapid recharge suggests that the lens either takes such recharge into storage very rapidly discharges it rapidly without taking it into storage or some combination of both significant vadose buffering of recharge to the lens is indicated by the fact that simulations assuming that the recharge from precipitation received in any given month is transmitted to the lens during the same month consistently over predict observed peak mean monthly water levels and under predict the minima

putslaagte 1 pl1 the doring river and the later middle stone age in southern africa s winter rainfall zone abstract existing data suggest weak human occupation of southern africa s winter rainfall zone wrz during later marine isotope stage mis 3 the causes of which are unknown here we report briefly on the results of recent surveys of alluvial terrace sites of the doring river in the wrz which document occupation over a broad expanse of the later middle stone age msa and pleistocene later stone age we then report on test excavations at one terrace site denoted putslaagte site 1 pl1 describe in detail the assemblage of flaked stone artefacts produced from that excavation and present two osl ages obtained from 0 8 m to 1 5 m below surface the results suggest that a artefact accumulations at pl1 are dense b the technological systems documented are characteristically msa but differ in form from the range of systems known from other excavated sites in the region and c that the assemblages accumulated in mis 3 taken together with the survey data the results introduce new variation into the later msa in southern africa and imply reorganisation of land use in the wrz in late mis 3 rather than abandonment we suggest that a research emphasis on rock shelter deposits may have produced misleading depictions of regional occupation

predicting aquifer characteristics to enhance hydrogeophysical model in fractured karstified rocks of dammam formation at bahr al najaf basin iraq groundwater represents a major water source in bahr al najaf basin so the knowledge of the aquifer parameters is an essential goal to assess and manage groundwater resources a comprehensive view of the fractured and karstified aquifers within dammam formation at bahr al najaf basin is very important because the karstified environments are very complex this study is an attempt to extract mathematically empirical relationships between the hydraulic parameters and the geoelectrical properties to improve the construction of a hydrogeophysical model instead of using the conventional procedures of pumping tests or drill new well which need great effort and high cost the enhanced hydrogeophysical model shows that the main aquifer has a uniform lithology of carbonate rocks good water saturation and belongs to m dammam member the correlation between hydraulic conductivity k m day and aquifer resistivity rho 0 m gave a logical relationship in such kind of aquifer which has correlation coefficient r2 equals to 0 737 in addition the correlation between transmissivity t m2 day and both of transverse resistance tr m2 and longitudinal conductance sl 1 revealed the similarity in lithological characteristics of middle dammam aquifer due to the approximately equal values of strong r2 0 862 and 0 868 respectively this may be due to the nature of the studied area as a discharge zone which has a good porosity varphi of 22 and a high water saturation sw equals to 1 approximately the extracted relationship of direct proportionality between t m2 day and sl 1 is an important one therefore this relationship can be used directly to calculate t m2 day mathematically in the present study the relations between the hydraulic parameters and the geoelectrical properties are expressed as linear equations instead of nonlinear because we believe that it is mathematically more acceptable and reliable for hard rock aquifers that the m dammam aquifer is confined with a fully saturated thickness in addition the comparison between r2 of the linear and nonlinear relation of t m2 day with tr m2 and t m2 day with sl 1 appeared to have little divergence of r2 equal to 0 028 and 0 001 respectively

liquid water storage in snow and ice in 86 eastern alpine basins and its changes from 1970 97 to 1998 2006

estimating groundwater recharge for an arid karst system using a combined approach of time lapse camera monitoring and water balance modelling groundwater is the principal water resource in semi arid and arid environments therefore quantitative estimates of its replenishment rate are important for managing groundwater systems in dry regions karst outcrops often show enhanced recharge rates compared with other surface and sub surface conditions areas with exposed karst features like sinkholes or open shafts allow point recharge even from single rainfall events using the example of the as sulb plateau in saudi arabia this study introduces a cost effective and robust method for recharge monitoring and modelling in karst outcrops the measurement of discharge of a representative small catchment 4 0 middle dot 104 m2 into a sinkhole and hence the direct recharge into the aquifer was carried out with a time lapse camera during the monitoring period of two rainy seasons autumn 2012 to spring 2014 four recharge events were recorded afterwards recharge data as well as proxy data about the drying of the sediment cover are used to set up a conceptual water balance model the model was run for 17 years 1971 to 1986 and 2012 to 2014 simulation results show highly variable seasonal recharge precipitation ratios between 0 and 0 27 in addition to the amount of seasonal precipitation this ratio is influenced by the interannual distribution of rainfall events overall an average annual groundwater recharge for the doline sinkhole catchment on as sulb plateau of 5 1 mm has estimated for the simulation period copyright c 2015 john wiley sons ltd c 2016 john wiley sons inc

petrography and diagenesis of silcrete from the kalahari basin and cape coastal zone southern africa abstract silcrete is widely distributed in southern africa and occurs both in genetic association with deeply weathered bedrock weathering profile type and as a significant component of the cenozoic kalahari beds where it has formed through silicification of a variety of continental deposits nonweathering profile type silcrete fabrics are classified into four major types gs grain supported skeletal quartz grains in contact f floating skeletal grains floating in matrix m matrix skeletal grains 5 of volume and c conglomeratic detrital component containing pebbles f and m fabric types are subdivided on the presence absence of glaebules replacement by silica of a precursor matrix can account for the development of all four fabric types but at least some gs and c fabr c silcretes have formed by passive silica precipitation in packing voids glaebules and colloform features predominantly composed of concentrations of anatase and iron oxide are common in weathering profile silcretes but their precise origin is uncertain authigenic silica is present as megaquartz microquartz length slow and length fast chalcedony predominantly in void fills cryptocrystalline silica and opal ct depending on the silica and ionic concentrations of pore waters ph and host sediment characteristics diagnostic petrographic features including glaebules colloform structures and chalcedonic vugh fills may be used in conjunction with geochemical data and sedimentary associations to interpret silcretes in the stratigraphic record with respect to weathering profile types formed in humid low ph environments or nonweathering profile types formed in high ph semiarid to arid environments

technological successions in the middle stone age sequence of diepkloof rock shelter western cape south africa the southern african msa comprises a series of phases of unique technological innovations that fuel current models on the evolutionary processes of anatomically modern humans however the nature and variability of these technological phases remain poorly documented this study reports on the previously unpublished sequence of diepkloof rock shelter south africa and investigates the main technological changes therein particularly emphasizing the emergence succession and disappearance of the still bay sb and the howiesons poort hp we argue for technological change that occurred at different rates and under the influence of variable driving factors our model implies that the sb and the hp are not related to the influx of new populations but have regionally specific origins unlike the other techno complexes the hp at diepkloof is subdivided into different phases early intermediate and late but only the upper phases resemble the so called classic hp finally the technological sequence of diepkloof questions the homogeneous picture which has been so far assumed for the southern african msa and places emphasis on the importance of exploring long regional sequences

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

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

osl and tl dating of the middle stone age sequence at diepkloof rock shelter south africa a clarification diepkloof rock shelter offers an exceptional opportunity to study the onset and evolution of both still bay sb and howiesons poort hp techno complexes however previous age estimates based on luminescence dating of burnt quartzites tribolo et al 2009 and of sediments jacobs et al 2008 were not in agreement here we present new luminescence ages for 17 rock samples equivalent dose estimated with a sar itl protocol instead of classical maad tl as well as for 5 sediment samples equivalent dose estimated with sar single grain osl protocol and an update of the 22 previous age estimates for burnt lithics modified calibration and beta dose estimates while a good agreement between the rock and sediment ages is obtained these estimates are still significantly older than those reported by jacobs et al 2008 after our own analyses of the sediment from diepkloof it is suspected that these authors did not correctly chose the parameters for the equivalent dose determination leading to an underestimate of the equivalent doses and thus of the ages from bottom to top the mean ages are 100 10 ka for stratigraphic unit su noel and 107 11 ka for su mark uncharacterized lower msa 100 10 ka for su lynn leo pre sb type lynn 109 10 ka for sus kim larry sb 105 10 ka for sus kerry kate and 109 10 ka for su jess early hp 89 8 ka for su jude msa type jack 77 8 ka for su john 85 9 ka for su fox 83 8 ka for su fred and 65 8 ka for su ob5 intermediate hp 52 5 ka for sus ob2 4 late hp this chronology together with the technological analyses greatly modifies the current chrono cultural model regarding the sb and the hp and has important archaeological implications indeed sb and hp no longer appear as short lived techno complexes with synchronous appearances for each and restricted to oxygen isotopic stage ois 4 across south africa as suggested by jacobs et al 2008 2012 rather the sequence of diepkloof supports a long chronology model with an early appearance of both sb and hp in the first half of ois 5 and a long duration of the hp into ois 3 these new dates imply that different technological traditions coexisted during ois 5 and 4 in southern africa and that sb and hp can no longer be considered as horizon markers

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

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

determining the seasonality of groundwater recharge using water isotopes a case study from the upper north han river basin korea the stable isotopes of oxygen and hydrogen were used to determine the seasonal contributions of precipitation to groundwater recharge at a forested catchment area in the upper north han river basin korea a comparison of the stable isotopic signatures of groundwater and precipitation indicates that the precipitations which occurred during both the dry and rainy seasons are the important source of groundwater recharge in this region a stable isotopic signature shown in the stream waters at the upstream reaches is similar to that of groundwaters indicating that stream waters are mostly fed by groundwater discharge reservoir waters in the downstream flood control dams have lower deuterium excess values or d values compared with those of the upstream waters indicating a secondary evaporative enrichment these results can provide a basis for the effective management of groundwater and stream water resources in the north han river basin

stable isotope variations in modern tropical speleothems evaluating equilibrium vs kinetic isotope effects applications of speleothem calcite geochemistry in climate change studies require the evaluation of the accuracy and sensitivity of speleothem proxies to correctly infer paleoclimatic information the present study of harrison s cave barbados uses the analysis of the modern climatology and groundwater system to evaluate controls on the c and o isotopic composition of modern speleothems this new approach directly compares the 18 o and 13 c values of modern speleothems with the values for their corresponding drip waters in order to assess the degree to which isotopic equilibrium is achieved during calcite precipitation if modern speleothems can be demonstrated to precipitate in isotopic equilibrium then ancient speleothems suitable for paleoclimatic studies from the same cave environment may also have been precipitated in isotopic equilib rium if modern speleothems are precipitated out of isotopic equilibrium then the magnitude and direction of the c and o isotopic offsets may allow specific kinetic and or equilibrium isotopic fractionation mechanisms to be identified carbon isotope values for the majority of modern speleothem samples from harrison s cave fall within the range of equilibrium values predicted from the combined use of 1 calcite water fractionation factors from the literature 2 measured temperatures and 3 measured 13 c values of the dissolved inorganic carbon of drip waters calcite samples range from 0 8 higher to 1 1 lower than predicted values the 13 c depletions are likely caused by kinetically driven departures in the fractionation between hco3 aq and caco3 from equilibrium conditions caused by rapid calcite growth 13 c enrichments can be accounted for by rayleigh distillation of the hco3 aq reservoir during degassing of 13 c depleted co2 modern speleothems from harrison s cave are not in o isotopic equilibrium with their corresponding drip waters and are 0 2 to 2 3 enriched in 18 o relative to equilibrium values 18 o variations in modern calcite are likely controlled by kinetically driven changes in the fractionation between hco3 aq and caco3 from equilibrium conditions to nonequilibrium conditions consistent with rapid calcite growth in contrast to 13 c 18 o values of modern calcite may not be affected by rayleigh distillation during degassing because co2 hydration and hydroxylation reactions will buffer the o isotopic composition of the hco3 aq reservoir if the effects of rayleigh distillation manifest themselves in the o isotopic system they will result in 18 o enrichment in the hco3

trade winds drive pronounced seasonality in carbonate chemistry in a tropical western pacific island cave implications for speleothem paleoclimatology carbon dioxide concentrations in caves are a primary driver of rates of carbonate dissolution and precipitation exerting strong control on speleothem growth rate and geochemistry long term cave monitoring studies in mid latitude caves have observed seasonal variability in cave pco2 whereby airflow is driven by temperature contrasts between the surface and subsurface in tropical settings where diurnal temperature cycles are larger than seasonal temperature cycles it is has been proposed caves will ventilate on daily timescales preventing cave pco2 from increasing substantially above atmospheric pco2 by contrast the relatively small temperature difference between the surface and subsurface may be insufficient to drive complete ventilation of tropical caves here we present results of an 8 year cave monitoring study including observations of cave pco2 and carbonate chemistry at jinapsan cave guam 13 4 n 144 5 e we find that cave pco2 in jinapsan cave is both relatively high and strongly seasonal with cave pco2 ranging from 500 5000 ppm the seasonality of cave pco2 cannot be explained by temperature contrasts instead we find evidence that seasonal trade winds drive cave ventilation and modulate cave pco2 calcite deposition rates at seven drip sites in jinapsan cave are shown to be seasonally variable demonstrating that speleothem growth rates in jinapsan cave are strongly affected by seasonal variations in cave pco2 these results highlight the importance that advection can have on cave ventilation processes and carbonate chemistry seasonality in carbonate chemistry and calcite deposition in this cave effect the interpretation of speleothem based paleoclimate records this article is protected by copyright all rights reserved

estimating recharge in a tropical karst aquifer unique constraints on seasonal and spatial variations in recharge to the pleistocene limestone aquifer of barbados are obtained from the analysis of oxygen isotopic compositions of groundwater and rainwater conventional methods of estimating recharge are based on groundwater chloride variations coastal groundwater discharge and potential evapotranspiration these methods typically yield estimates of recharge for barbados that range from 9 to 20 of average annual rainfall with significant uncertainties that arise from poorly constrained model input parameters owing to the low relief and tropical climate of barbados variations in rainwater and groundwater 18o values are primarily influenced by the amount of rainfall with negligible temperature or altitude effects composite monthly rainwater 18o values are inversely related to rainfall while groundwater 18o values show little seasonal variability rainwater 18o values are equivalent to groundwater values only at the peak of the wet season by using mass balance the difference between groundwater and weighted mean rainwater 18o values gives recharge values these values are in general agreement with estimates by conventional methods 10 20 and provide unique additional information including the following 1 recharge is restricted to the wettest 1 3 months of the year and 2 there is less recharge at higher elevations the effective shift in 18o values between contemporaneous rainwater and groundwater via recharge is a useful tool for estimating temporal and spatial variability in recharge and must be considered in paleoclimatic studies where climate inferences are based on groundwater 18o values preserved in the geologic record

an improved single grain osl chronology for the sedimentary deposits from diepkloof rockshelter western cape south africa the single grain optically stimulated luminescence osl chronology for the sedimentary deposit at diepkloof rockshelter reported by jacobs et al 2008c has recently been critiqued and several reasons proposed for why the osl ages for the intermediate and early howieson s poort hp and still bay sb techno complexes might be inaccurate tribolo et al 2013 presented a series of osl and thermoluminescence tl ages that were in agreement with each other but for some part of the sequence at least were much older than the osl chronology of jacobs et al 2008c in this paper we have tested the criticisms of tribolo et al 2013 and colleagues related to both the equivalent dose de estimates and the beta dose rates by performing a series of targeted experiments combined with updates and re assessments of our error calculations we show that the de estimates are stable over a range of alternative measurement conditions and also over time we also demonstrate the reproducibility of our measurement procedures for the beta dose rates and their accuracy tested against a range of independently obtained estimates we show that for the stratigraphic units sus where there are major discrepancies in age between jacobs et al 2008c and tribolo et al 2013 notably the intermediate hp and early hp and for which both studies had single grain osl ages the estimation of potassium k in the sediment surrounding the dated grains is critical we provide new and updated de and dose rate estimates and final ages which we compare with our previous age estimates and those of tribolo et al 2013 the differences in the size of the errors associated with the ages reported in the two independent studies are also addressed we can show that our ages are robust and consistent with the original chronology but we cannot satisfactorily explain why the tl and osl ages provided by tribolo et al 2013 might be wrong so the dating conundrum at diepkloof rockshelter remains as a result we caution against the development of hp and sb age models based on only one of the chronologies for this site at this stage extrapolation of the tribolo et al 2013 chronology to a re interpretation of the southern african msa would appear to be premature especially as the ages do not differ systematically between the two studies and as differences between tl and osl ages are not an issue at other sites in southern africa where both dating methods have been applied further work is needed to resolve the question of the diepkloof chronology

influence of sea water intrusion and agricultural production on the blato aquifer island of korcula croatia the blato aquifer is situated on the western side of the island of korcula southern dalmatia croatia the terrain is built of karstified carbonate rocks mostly of the cretaceous age in the blatsko karst polje there are four water supply wells with a total yield of about 60 l s the catchment area is 28 km2 the whole terrain is tectonically disturbed and compressed the most permeable fracture system is perpendicular to the structural b axes which gives rise to a general groundwater direction towards the island s northern coast average precipitation is 850 mm year but when there is less than 700 mm year there is a high possibility of sea water intrusion during the summer season the risk significantly increases when dry years repeat hydrochemical research has shown that two main pollution sources occur at different hydrological moments sea water intrusion happens in the dry summer period when there is maximal extraction and almost no recharge and the washing of nitrates and other humanly caused pollution indicators from the soil and epikarst belt during the rainy season all factors must be taken into account when planning management and protection of such a sensitive environment

stable isotope study of cave percolation waters in subtropical brazil implications for paleoclimate inferences from speleothems we analyze the interannual monthly variability of oxygen isotope ratios in data from iaea stations along the atlantic coast of south america between 238 and 348 s to evaluate the influence of parameters such as temperature rainfall amount and moisture source contribution on meteoric water recharging two karst systems in subtropical brazil in addition a 2 year monitoring program performed on soil and cave drip and rimstone pool waters from sampling sites with contrasting discharge values and located at 100 and 300 m below the surface in the santana cave system 24831v s 48843v w is used to test the influence of hydrologic and geologic features on the temporal variations of seepage water d 18 o interannual monthly variations in d 18 o of rainfall reflect primarily regional changes in moisture source contribution related to seasonal shifts in atmospheric circulation from a more monsoonal regime in summer negative values of d 18 o to a more extratropical regime in winter positive values of d 18 o variations in groundwater d 18 o indicate that the climatic signal of recent rainfall events is rapidly transmitted through the relatively deep karst aquifer to the cave drip waters regardless of location of collection in the cave in addition the data also suggest that water replenishment in the system is triggered by the increase in hydraulic head during periods when recharge exceeds the storage capacity of the soil and epikarst reservoirs significant perturbations in the groundwater composition characterized by more positive values of d 18 o are probably connected to an increased atlantic moisture contribution associated with extratropical precipitation this implies that the d 18 o of speleothems from caves in this region may be a suitable proxy for studying