depositional and sea level history from mis 6 termination ii to mis 3 on the southern continental shelf of south africa abstract pleistocene shoreline deposits comprised of calcified shallow marine palaeobeach and aeolian palaeodune facies found along mid latitude coastlines can be useful indicators of past sea levels here we describe a succession of such deposits that are presently exposed both above subaerial and below submerged mean sea level along the southern cape coast of south africa 18 km east of the town of mossel bay the submerged units provide a window on late pleistocene coastal processes as palaeoshoreline deposits in this study extend to water depths of up to 55 m on the mid shelf five sedimentary facies were identified in the strata and were compared to modern depositional environments of the local littoral zone which include aeolian dune upper shoreface foreshore intertidal swash and back barrier settings twenty two geological units were observed and mapped some of these units were directly dated with optically stimulated luminescence osl dating osl ages were obtained for ten samples from the subaerial and twelve samples from the submerged deposits those geological units not directly dated were interpreted based on sedimentology and field stratigraphic relationships to dated units the stratigraphy and chronology of the succession indicates a record of initial deposition during termination ii t ii meltwater events preceding and leading to marine isotope stage mis 5e indicators for multiple sea level fluctuations between mis 5d and mis 4 and sediment deposition at the end of mis 4 and start of mis 3 are also found both regressive and transgressive depositional cycles are well preserved in the succession we propose that palaeodune and palaeobeach deposits along the south coast of south africa have no clear preference for deposition during sea level transgressions or regressions sediment deposition more closely mirrors the rate of sea level change with deposition and preservation either during times of rapid sea level movement or oscillation around still stand events periods of relatively slow average rise or fall of sea level are represented by erosional planation surfaces in this record

information content of slug tests for estimating hydraulic properties in realistic high conductivity aquifer scenarios summary a recently developed unified model for partially penetrating slug tests in unconfined aquifers malama et al in press provides a semi analytical solution for aquifer response at the wellbore in the presence of inertial effects and wellbore skin and is able to model the full range of responses from overdamped monotonic to underdamped oscillatory while the model provides a unifying framework for realistically analyzing slug tests in aquifers with the ultimate goal of determining aquifer properties such as hydraulic conductivity k and specific storage s s it is currently unclear whether parameters of this model can be well identified without significant prior information and thus what degree of information content can be expected from such slug tests in this paper we examine the information content of slug tests in realistic field scenarios with respect to estimating aquifer properties through analysis of both numerical experiments and field datasets first through numerical experiments using markov chain monte carlo methods for gauging parameter uncertainty and identifiability we find that 1 as noted by previous researchers estimation of aquifer storage parameters using slug test data is highly unreliable and subject to significant uncertainty 2 joint estimation of aquifer and skin parameters contributes to significant uncertainty in both unless prior knowledge is available and 3 similarly without prior information joint estimation of both aquifer radial and vertical conductivity may be unreliable these results have significant implications for the types of information that must be collected prior to slug test analysis in order to obtain reliable aquifer parameter estimates for example plausible estimates of aquifer anisotropy ratios and bounds on wellbore skin k should be obtained if possible a priori secondly through analysis of field data consisting of over 2500 records from partially penetrating slug tests in a heterogeneous highly conductive aquifer we present some general findings that have applicability to slug testing in particular we find that aquifer hydraulic conductivity estimates obtained from larger slug heights tend to be lower on average presumably due to non linear wellbore losses and tend to be less variable presumably due to averaging over larger support volumes supporting the notion that using the smallest slug heights possible to produce measurable water level changes is an important strategy when mapping aquifer heterogeneity finally we present results specific to characterization of the aquifer at the boise hydrogeophysical research site specifically we note that 1 k estimates obtained using a range of different slug heights give similar results generally within 20 2 correlations between estimated k profiles with depth at closely spaced wells suggest that k values obtained from slug tests are representative of actual aquifer heterogeneity and not overly affected by near well media disturbance i e skin 3 geostatistical analysis of k values obtained indicates reasonable correlation lengths for sediments of this type and 4 overall k values obtained do not appear to correlate well with porosity data from previous studies

identification of groundwater basin shape and boundary using hydraulic tomography abstract shapes and boundary types of a groundwater basin play essential roles in the analysis of groundwater management and contaminant migration hydraulic tomography ht a recently developed new approach for high resolution characterization of aquifers is not only an inverse method but a logical strategy for collecting non redundant hydraulic information in this study ht was applied to synthetic 2 d aquifers to investigate its feasibility to map the irregular shapes and types of the aquifer boundaries we first used the forward model of vsaft2 to simulate hydraulic responses due to ht surveys in the aquifer with irregular geometry and predetermined constant head conditions at some boundaries and no flow conditions at others the simsle simultaneous successive linear estimator inverse model in vsaft2 was then used to interpret the simulated ht data to estimate the spatial distribution of hydraulic properties of the aquifer using a domain with a wrong geometry surrounded by boundaries of a constant head condition the inverse modeling experiment used steady state and transient states data from the ht forward simulations and it used the same monitoring network as in the aquifer with irregular geometry to assess the ability of ht for detecting types and shapes of the boundary as well as heterogeneity in the aquifer results of the experiment show that no flow boundaries which were incorrectly treated as constant head boundaries in inverse models were portrayed as low permeable zones of the aquifer near the boundaries overall the results show that ht could delineate not only the irregular shape of the aquifer in general but also heterogeneity in the aquifer improvements of the estimation with prior information of transmissivity and storage coefficient was also investigated the study shows that using homogeneous initial guess parameters resulted in a slightly better estimate than others moreover this study employs monte carlo simulations to ensure statistically meaningful conclusions

hydrogeologic facies models to delineate large scale spatial trends in glacial and glaciofluvial sediments recent interest in contaminant transport in ground water has led hydrogeologists to the conclusion that predicting the movement of solutes requires information on the distribution of spatial trends and heterogeneities in porous media description of spatial trends has long been of interest to sedimentologists who have produced a large body of geologic information on the subject in this paper facies models are used to construct conceptual models of hydrogeologic facies for glacialmeltwater stream sediment and till these hydrogeologic facies models which delineate large scale trends in heterogeneity are appropriate for use in designing hydrogeologic field tests and for estimating input to regional ground water flow and transport models this paper treats each facies as a homogeneous anisotropic hydrogeologic unit the models presented herein conceptualize the hydrogeologic relationships among facies and illustrate one method of converting the apparent chaos in nature into an orderly system that can be tested scientifically and modeled mathematically the principles used to create conceptual models of hydrogeologic facies for the types of sediment considered in this paper can be extended to other sedimentary environments it should be recognized however that such models do not address the small scale heterogeneity present within individual facies additional basic research is required to measure hydraulic conductivity variation within representative hydrogeologic facies and to develop statistical descriptions to represent the variations such detailed descriptions of hydraulic conductivity may be necessary to describe ground water flow at a local scale for analysis of contaminant transport

the relative importance of head flux and prior information in hydraulic tomography analysis using cross correlation analysis we demonstrate that flux measurements at observation locations during hydraulic tomography ht surveys carry nonredundant information about heterogeneity that are complementary to head measurements at the same locations we then hypothesize that a joint interpretation of head and flux data even when the same observation network as head has been used can enhance the resolution of ht estimates subsequently we use numerical experiments to test this hypothesis and investigate the impact of flux conditioning and prior information such as correlation lengths and initial mean models i e uniform mean or distributed means on the ht estimates of a nonstationary layered medium we find that the addition of flux conditioning to ht analysis improves the estimates in all of the prior models tested while prior information on geologic structures could be useful its influence on the estimates reduces as more nonredundant data i e flux are used in the ht analysis lastly recommendations for conducting ht surveys and analysis are presented

aquifer heterogeneity characterization with oscillatory pumping sensitivity analysis and imaging potential 1 periodic pumping tests in which a fluid is extracted during half a period then reinjected have been used historically to estimate effective aquifer properties in this work we suggest a modified approach to periodic pumping test analysis in which one uses several periodic pumping signals of different frequencies as stimulation and responses are analyzed through inverse modeling using a steady periodic model formulation we refer to this strategy as multifrequency oscillatory hydraulic imaging oscillating pumping tests have several advantages that have been noted including no net water extraction during testing and robust signal measurement through signal processing through numerical experiments we demonstrate additional distinct advantages that multifrequency stimulations have including 1 drastically reduced computational cost through use of a steady periodic numerical model and 2 full utilization of the aquifer heterogeneity information provided by responses at different frequencies we first perform fully transient numerical modeling for heterogeneous aquifers and show that equivalent results are obtained using a faster steady periodic heterogeneous numerical model of the wave phasor the sensitivities of observed signal response to aquifer heterogeneities are derived using an adjoint state based approach which shows that different frequency stimulations provide complementary information finally we present an example 2 d application in which sinusoidal signals at multiple frequencies are used as a data source and are inverted to obtain estimates of aquifer heterogeneity these analyses show the different heterogeneity information that can be obtained from different stimulation frequencies and that data from several sinusoidal pumping tests can be rapidly inverted using the steady periodic framework

multi instrument observations of sed during 24 25 october 2011 storm implications for sed formation processes 1 we present multiple instrument observations of a storm enhanced density sed during the 24 25 october 2011 intense geomagnetic storm formation and the subsequent evolution of the sed and the midlatitude trough are revealed by global gps vertical total electron content maps in addition we present high time resolution poker flat incoherent scatter radar pfisr observations of ionospheric profiles within the sed we divided the sed observed by pfisr into two parts both parts are characterized by elevated ionospheric peak height hmf2 and total electron content compared to quiet time values however the two parts of the sed have different characteristics in the electron temperature te the f region peak density nmf2 and convection flows the first part of the sed is associated with enhanced te in the lower f region and reduced te in the upper f region and is collocated with northward convection flows the nmf2 was lower than quiet time values the second part of the sed is associated with significantly increased nmf2 elevated te at all altitudes and is located near the equatorward boundary of large northwestward flows based on these observations we suggest that the mechanisms responsible for the formation of the two parts of the sed may be different the first part is due to equatorward expansion of the convection pattern and the projection of northward convection flows in the vertical direction which lifts the ionospheric plasma to higher altitudes and thus reduces the loss rate of plasma recombination the second part is more complicated besides equatorward expansion of the convection pattern and large upward flows evidences of other mechanisms including horizontal advection due to fast flows energetic particle precipitation and enhanced thermospheric wind in the topside ionosphere are also present estimates show that contribution from precipitating energetic protons is at most 10 of the total f region density the thermospheric wind also plays a minor role in this case

3 d transient hydraulic tomography in unconfined aquifers with fast drainage response we investigate through numerical experiments the viability of three dimensional transient hydraulic tomography 3dtht for identifying the spatial distribution of groundwater flow parameters primarily hydraulic conductivity k in permeable unconfined aquifers to invert the large amount of transient data collected from 3dtht surveys we utilize an iterative geostatistical inversion strategy in which outer iterations progressively increase the number of data points fitted and inner iterations solve the quasilinear geostatistical formulas of kitanidis in order to base our numerical experiments around realistic scenarios we utilize pumping rates geometries and test lengths similar to those attainable during 3dtht field campaigns performed at the boise hydrogeophysical research site bhrs we also utilize hydrologic parameters that are similar to those observed at the bhrs and in other unconsolidated unconfined fluvial aquifers in addition to estimating k we test the ability of 3dtht to estimate both average storage values specific storage ss and specific yield sy as well as spatial variability in storage coefficients the effects of model conceptualization errors during unconfined 3dtht are investigated including 1 assuming constant storage coefficients during inversion and 2 assuming stationary geostatistical parameter variability overall our findings indicate that estimation of k is slightly degraded if storage parameters must bemore jointly estimated but that this effect is quite small compared with the degradation of estimates due to violation of structural geostatistical assumptions practically we find for our scenarios that assuming constant storage values during inversion does not appear to have a significant effect on k estimates or uncertainty bounds less

melting ice sheets 400 000 yr ago raised sea level by 13 m past analogue for future trends abstract marine isotope stage mis 11 was possibly the longest 423 000 362 000 yr ago and warmest interglacial of the entire quaternary period this resulted from a special arrangement of earth s orbital parameters similar to the present interglacial mis 1 suggesting that mis 11 provides an analogue for future natural climate forcing and sea levels although precise documentation of mis 11 sea level history is therefore crucial especially considering additional impetus from anthropogenic warming the maximum mis 11 sea level remains highly contentious estimates from onshore indicators have ranged from below present sea level to about 20 m resulting from uncertainties in reliability of sea level indicators estimates of their subsequent displacement by vertical crustal motion and in dating we used a clear and unambiguous sea level indicator interface between subtidal and intertidal deposits in well exposed regressive raised shoreline deposits along south africa s southern coast the coast is stable in terms of tectonic setting and falls within a zone of low predicted glacio isostatic adjustment gia and low sensitivity for plausible model parameters the sea level indicators were directly dated using thermally transferred optically stimulated luminescence tt osl which gave a mean age of 390 ka corresponding with mis 11 we determined a precise maximum elevation of 14 m for the mis 11 sea level indicator which corrected for minor crustal uplift and gia yielded a eustatic sea level of 13 m 2 m the complete mis 11 transgressive regressive shoreline succession is preserved and the wave cut platform extends 950 m inland from the present shoreline indicating a prolonged highstand we have also documented sea level fluctuations during mis 11 including an earlier lower highstand close to present sea level which may explain the lower elevation range of some previous estimates at one locality mis 11 deposits form a sea cliff against which mis 5e sediments at an elevation of 6 2 m abut the 13 m mis 11 sea level tallies with total melting of the greenland and west antarctica ice sheets regarded as most susceptible to melting our data predict notably higher sea levels in the future regardless of anthropogenic influence on climate

should hydraulic tomography data be interpreted using geostatistical inverse modeling a laboratory sandbox investigation the robust performance of hydraulic tomography ht based on geostatistics has been demonstrated through numerous synthetic laboratory and field studies while geostatistical inverse methods offer many advantages one key disadvantage is its highly parameterized nature which renders it computationally intensive for large scale problems another issue is that geostatistics based ht may produce overly smooth images of subsurface heterogeneity when there are few monitoring interval data therefore some may question the utility of the geostatistical inversion approach in certain situations and seek alternative approaches to investigate these issues we simultaneously calibrated different groundwater models with varying subsurface conceptualizations and parameter resolutions using a laboratory sandbox aquifer the compared models included 1 isotropic and anisotropic effective parameter models 2 a heterogeneous model that faithfully represents the geological features and 3 a heterogeneous model based on geostatistical inverse modeling the performance of these models was assessed by quantitatively examining the results from model calibration and validation calibration data consisted of steady state drawdown data from eight pumping tests and validation data consisted of data from 16 separate pumping tests not used in the calibration effort results revealed that the geostatistical inversion approach performed the best among the approaches compared although the geological model that faithfully represented stratigraphy came a close second in addition when the number of pumping tests available for inverse modeling was small the geological modeling approach yielded more robust validation results this suggests that better knowledge of stratigraphy obtained via geophysics or other means may contribute to improved results for ht

characterization of aquifer heterogeneity using transient hydraulic tomography 1 hydraulic tomography is a cost effective technique for characterizing the heterogeneity of hydraulic parameters in the subsurface during hydraulic tomography surveys a large number of hydraulic heads i e aquifer responses are collected from a series of pumping or injection tests in an aquifer these responses are then used to interpret the spatial distribution of hydraulic parameters of the aquifer using inverse modeling in this study we developed an efficient sequential successive linear estimator ssle for interpreting data from transient hydraulic tomography to estimate three dimensional hydraulic conductivity and specific storage fields of aquifers we first explored this estimator for transient hydraulic tomography in a hypothetical one dimensional aquifer results show that during a pumping test transient heads are highly correlated with specific storage at early time but with hydraulic conductivity at late time therefore reliable estimates of both hydraulic conductivity and specific storage must exploit the head data at both early and late times our study also shows that the transient heads are highly correlated over time implying only infrequent head measurements are needed during the estimation applying this sampling strategy to a well posed problem we show that our ssle can produce accurate estimates of both hydraulic conductivity and specific storage fields the benefit of hydraulic tomography for ill posed problems is then demonstrated finally to affirm the robustness of our ssle approach we apply the ssle approach to a hypothetical three dimensional heterogeneous aquifer

last interglacial fossil elephant trackways dated by osl aar in coastal aeolianites still bay south africa abstract the impressive pleistocene coastal aeolianite exposures in sea cliffs east of still bay on the west southern coast of south africa host a rich archive of fossil mammalian trackways including the african elephant loxodonta africana neither the ichnofossils nor their host sediments have been described in any detail and chronologies remained uncertain this paper presents a new optically stimulated luminescence osl and amino acid racemisation aar chronology the first joint application of osl aar dating in south africa this provides a temporal framework for assessing the palaeoenvironmental significance of dune sedimentation patterns pedogenesis and ichnology the pleistocene aeolianite exposures at still bay represent the recently eroded remnants of a dune cordon mainly built by coalesced parabolic dune systems sedimentary facies are dominated by large scale planar cross stratification formed by foreset progradation in the nose and trailing arms of the dunes and low angle bedding chiefly representing sedimentation in low relief interdune terrain the main dune building wind regime was westerly associated with cyclonic polar frontal systems as at the present time the osl and aar dating demonstrate ages ranging from mis 5e to 5b and termination of pleistocene aeolian sedimentation at 90 ka the pleistocene aeolianite is separated from the overlying holocene dunes dated to 8 ka by a major hiatus recorded by a horizon of intense pedogenesis elephant footprints were seen in profile as casts on the underside of beds and as natural impressions the taphonomic processes controlling the morphology and preservation of these unique ichnofossils were found to be complex the presence of loxodonta africana at still bay represents the southernmost occurrence of this species recorded to date and possibly a closer proximity of woodland during mis 5 this and other observations may indicate a higher moisture regime than at present there is no available evidence that the elephants were predated by contemporary middle stone age people

a temporal sampling strategy for hydraulic tomography analysis 1 this paper investigates optimal sampling times of drawdowns for the analysis of hydraulic tomography ht survey the investigation was carried out by analyzing the spatial and temporal evolution of cross correlations between the head responses at an observation well and transmissivity t and storage coefficient s properties during a pumping test in homogeneous and heterogeneous aquifers the analysis shows that the cross correlation between the head and s values is limited to the region between the observation and the pumping well in the aquifers it reaches the highest value near the early time tm and decays to zero afterwards the time tm is approximately equal to the time t0 at which the extrapolated drawdown from the first straight line portion of an observed drawdown log time plot becomes zero at early times the high cross correlation between the head and t is confined to the region between the observation and the pumping well this region then evolves into two humps one on each side of the circular region encompassing the observation well and the pumping well the size of the two humps expands and their values reach the maximum as flow reach steady state as a consequence we hypothesize that pairs of head data at t0 and those at either the steady state or a late time during an ht survey could yield the best estimates of the heterogeneous t and s fields results from numerical experiments have verified this hypothesis and demonstrated that this sampling strategy is generally applicable even when the boundary condition is unknown we therefore recommend in principle that 1 carrying out pumping tests of ht surveys for sufficiently long period of time such that drawdown reaches the entire area of interest and 2 using a constant head or zero drawdown for all boundaries during the inverse modeling analysis

on the importance of geological data for three dimensional steady state hydraulic tomography analysis at a highly heterogeneous aquifer aquitard system abstract hydraulic tomography ht has been shown to map subsurface heterogeneity accurately through the joint interpretation of multiple pumping tests previous research has shown that smooth hydraulic conductivity k estimates are obtained beyond where pumping observation data are available using the geostatistical inversion approach when the inversion begins with a homogeneous k and when data densities are not high however geological data are typically available through outcrops and borehole logs to provide geological variability therefore we investigate the usefulness of geological data for ht analysis at a highly heterogeneous field site by 1 comparing calibrated geological models of two different resolutions to two homogeneous and four highly parameterized geostatistical inverse models in terms of both model calibration and validation performances as well as correspondence of estimated k values with permeameter estimated k profiles along boreholes and 2 using geological models as prior information for the geostatistical inversion approach results reveal that the simultaneous calibration of geological models to seven pumping test data yields k values that correctly reflect the general patterns of vertical distributions of permeameter estimated k we also find that the geostatistical inversion approach using a geological model as prior information performs better for both model calibration and validation than using a homogenous k as a prior and more importantly improves the correspondence of k estimates to permeameter test results along wells as well as in preserving geological features where drawdown measurements are lacking overall our results suggest the joint use of both geological and pumping test data for ht analysis when accurate geological data are available

three dimensional imaging of aquifer and aquitard heterogeneity via transient hydraulic tomography at a highly heterogeneous field site abstract previous studies have shown that geostatistics based transient hydraulic tomography tht is robust for subsurface heterogeneity characterization through the joint inverse modeling of multiple pumping tests however the hydraulic conductivity k and specific storage ss estimates can be smooth or even erroneous for areas where pumping observation densities are low this renders the imaging of interlayer and intralayer heterogeneity of highly contrasting materials including their unit boundaries difficult in this study we further test the performance of tht by utilizing existing and newly collected pumping test data of longer durations that showed drawdown responses in both aquifer and aquitard units at a field site underlain by a highly heterogeneous glaciofluvial deposit the robust performance of the tht is highlighted through the comparison of different degrees of model parameterization including 1 the effective parameter approach 2 the geological zonation approach relying on borehole logs and 3 the geostatistical inversion approach considering different prior information with without geological data results reveal that the simultaneous analysis of eight pumping tests with the geostatistical inverse model yields the best results in terms of model calibration and validation we also find that the joint interpretation of long term drawdown data from aquifer and aquitard units is necessary in mapping their full heterogeneous patterns including intralayer variabilities moreover as geological data are included as prior information in the geostatistics based tht analysis the estimated k values increasingly reflect the vertical distribution patterns of permeameter estimated k in both aquifer and aquitard units finally the comparison of various tht approaches reveals that differences in the estimated k and ss tomograms result in significantly different transient drawdown predictions at observation ports

ichnological evidence of semi aquatic locomotion in early turtles from eastern iberia during the carnian humid episode late triassic abstract some of the earliest european records of fossil turtle footprints late triassic middle carnian 227 237 ma are interpreted from 46 footprints from three outcrops domeno quesa and cortes de pallas located in the iberian range eastern spain the samples were obtained from upper triassic rocks in keuper facies they are characterized in the studied area by two well defined evaporitic sequences separated by a detrital stratigraphic interval constituting the manuel sandstones formation in which the studied fossil footprints were recorded these fluvial deposits are correlatable with the carnian humid episode the footprints are tridactyl and tetradactyl mainly digitigrade and elongated scratch marks are common the digit traces present triangular and curved claws the morphology of these marks suggests they were produced by the autopodium of a tetrapod animal while swimming near the bottom and they are consistent with the anatomical features of a turtle s manus other footprints were produced by turtles walking in wet medium to coarse grained sand in a subaerial environment a short trackway is identified sharing similarities with both the ichnogenera emydhipus and chelonipu s the observed tracks support a freshwater semi aquatic habit for some stem turtles during the early late triassic these are remarkably ancient turtle tracks close to the origin of the group as indicated by skeletal fossils they confirm that the earliest forms were narrowly related to aquatic fluvial environments

sequential aquifer tests at a well field montalto uffugo scalo italy 1 this paper investigates our ability to characterize an aquifer using a sequential aquifer test in a well field that consists of six wells during the test we pumped water out from the aquifer at one well and monitored the water level changes at the rest of the wells to obtain a set of five well hydrographs by pumping at another of the six wells we obtained another set of five hydrographs this procedure was repeated until each of the six wells was pumped we then analyzed the six sets of hydrographs using the classical drawdown time the drawdown distance and the drawdown distance time methods results of the analysis confirm recent findings that the transmissivity estimates vary significantly at early time and stabilize at late time at late time the estimated values from all hydrographs are similar overall but vary slightly according to the locations of the pumping and observation wells in contrast storage coefficient estimates stabilized rapidly to distinct values associated with the well locations we subsequently used a hydraulic tomography approach to include all hydrographs from the sequential aquifer test to estimate the spatially varying transmissivity and storage coefficient fields the estimated fields appear to be realistic they reflect the geologic setting and the behaviors of the well hydrographs although more definitive confirmation is needed

refining the eustatic sea level curve since the last glacial maximum using far and intermediate field sites the eustatic component of relative sea level change provides a measure of the amount of ice transferred between the continents and oceans during glacial cycles this has been quantified for the period since the last glacial maximum by correcting observed sea level change for the glacio hydro isostatic contributions using realistic ice distribution and earth models during the last glacial maximum lgm the eustatic sea level was 125 5 m lower than the present day equivalent to a land based ice volume of 4 6 4 9 107 km3 evidence for a non uniform rise in eustatic sea level from the lgm to the end of the deglaciation is examined the initial rate of rise from ca 21 to 17 ka was relatively slow with an average rate of ca 6 m ka 1 followed by an average rate of ca 10 m ka 1 for the next 10 ka significant departures from these average rates may have occurred at the time of the younger dryas and possibly also around 14 ka most of the decay of the large ice sheets was completed by 7 ka but 3 5 m of water has been added to the oceans since that time

new fossil sea turtle trackway morphotypes from the pleistocene of south africa highlight role of ichnology in turtle paleobiology more than 130 late pleistocene trackway sites from the coastal eolianites and beach deposits of the cape south coast south africa have previously mostly yielded tracks of large mammals and birds however two sites east of still bay and a third near garden route national park yield distinctive trackways of hatchling sea turtles made during the short posthatching postemergence interval when the trackmakers headed for the sea one assemblage of approximately parallel trackways indicates smaller loggerhead turtle hatchlings with alternating gaits and contrasts with a wider trackway indicating a leatherback turtle hatchling these are the world s first reports of fossil traces that document this brief run for the sea phenomenon they help delineate late pleistocene sea turtle breeding ranges and indicate climatic conditions along the cape south coast ichnotaxonomically defined swim tracks of large adult sea turtles are known from a few mesozoic sites likewise walking and swim traces of terrestrial freshwater turtles are also known from the mesozoic and cenozoic however as no ichnotaxonomy exists for these diagnostic hatchling trails we assign the trackways of the inferred loggerheads to the new ichnotaxon australochelichnus agulhasii ichnogen et ichnosp nov and the inferred leatherback trackway to marinerichnus latus ichnogen et ichnosp nov

on the importance of geological data for hydraulic tomography analysis laboratory sandbox study abstract this paper investigates the importance of geological data in hydraulic tomography ht through sandbox experiments in particular four groundwater models with homogeneous geological units constructed with borehole data of varying accuracy are jointly calibrated with multiple pumping test data of two different pumping and observation densities the results are compared to those from a geostatistical inverse model model calibration and validation performances are quantitatively assessed using drawdown scatterplots we find that accurate and inaccurate geological models can be well calibrated despite the estimated k values for the poor geological models being quite different from the actual values model validation results reveal that inaccurate geological models yield poor drawdown predictions but using more calibration data improves its predictive capability moreover model comparisons among a highly parameterized geostatistical and layer based geological models show that 1 as the number of pumping tests and monitoring locations are reduced the performance gap between the approaches decreases and 2 a simplified geological model with a fewer number of layers is more reliable than the one based on the wrong description of stratigraphy finally using a geological model as prior information in geostatistical inverse models results in the preservation of geological features especially in areas where drawdown data are not available overall our sandbox results emphasize the importance of incorporating geological data in ht surveys when data from pumping tests is sparse these findings have important implications for field applications of ht where well distances are large

crocodylomorph turtle and mammal tracks in dinosaur dominated middle upper jurassic and mid cretaceous ichnoassemblages of morocco abstract we report tetrapod traces from two stratigraphic intervals in morocco and discuss their palaeoecological implications in the first interval crocodylomorph footprints assigned to crocodylopodus meijidei are described from middle upper jurassic continental fluvial red beds of the isli formation in the imilchil region central high atlas morocco these traces are associated with a diverse dinosaur dominated ichnofauna including the footprints of theropods ornithischians sauropods and pterosaurs together with numerous invertebrate traces in the second interval we report crocodylomorph swim traces assigned to hatcherichnus isp turtle trackways assigned to emydhipus isp and isolated mammal footprints in the mid cretaceous midelt formation in the high moulouya region morocco these traces are also associated with a diverse dinosaur dominated ichnofauna including theropods and ornithopods as well as pterosaurs and abundant invertebrate traces together with plant remains conchostracans and fishes findings indicate a diverse community populating a fluvial brackish environment

capturing aquifer heterogeneity comparison of approaches through controlled sandbox experiments 1 groundwater modeling has become a vital component to water supply and contaminant transport investigations these models require representative hydraulic conductivity k and specific storage ss estimates or a set of estimates representing subsurface heterogeneity currently there are a number of approaches for characterizing and modeling k and ss heterogeneity in varying degrees of detail but there is a lack of consensus for an approach that results in the most robust groundwater models with the best predictive ability the main goal of this study is to compare different heterogeneity modeling approaches e g effective parameters geostatistics geological models and hydraulic tomography when input into a forward groundwater model and used to predict 16 independent cross hole pumping tests we first characterize a sandbox aquifer through single and cross hole pumping tests and then use these data to construct forward groundwater models of various complexities both homogeneous and heterogeneous distributions two effective parameter models are constructed 1 by taking the geometric mean of single hole test k and ss estimates and 2 calibrating effective k and ss estimates by simultaneously matching the response at all ports during a cross hole test heterogeneous models consist of spatially variable k and ss fields obtained via 1 kriging single hole data 2 calibrating a geological model and 3 conducting transient hydraulic tomography zhu and yeh 2005 the performance of these parameter fields are then tested through the simulation of 16 independent cross hole pumping tests our results convincingly show that transient hydraulic tomography produces the smallest discrepancy between observed and simulated drawdowns