stratification of the f 2 layer observed in southeast asia this paper describes the latitudinal variation in f2 stratification balan and bailey 1995 as observed by a number of oblique and vertical ionosondes operating in southeast asia during 1997 stratification of the f2 layer was seen at dip latitudes from 4 s to 18 s on the southern side of the magnetic equator but did not occur at the closest reflection point to the magnetic equator dip latitude 2 3 n the observed transient cusp vertical ionosonde or additional nose oblique ionosonde was defined as an f3 layer or an f1 5 layer depending on whether it occurred above or below the layer which maintained continuity with the normal f2 layer peak within the zone of occurrence the transient layer was commonly seen as an f3 layer at reflection points closest to the magnetic equator but invariably as an f1 5 layer at reflection points farther from the magnetic equator these observations suggest that the distortion in the equatorial electron density profile associated with the phenomenon moved toward the base of the f2 layer as magnetic field lines descended with increasing latitude stratification of the f2 layer commenced at the same local time e g 0845 lt in november 1997 throughout the longitudinal range of coverage and was associated with a rapid rise in f2 layer height following sunrise the stratification ended at times varying from 1300 lt to sunset and was associated with a fall in the height of f2 peak electron density the region of maximum f2 layer stratification lay between the magnetic equator and the peak of the southern equatorial anomaly

paleoclimatic signature in terrestrial flood deposits large scale process simulation was used to reconstruct the geologic evolution during the past 600 000 years of an alluvial fan in northern california in order to reproduce the sedimentary record the simulation accounted for the dynamics of river flooding sedimentation subsidence land movement that resulted from faulting and sea level changes paleoclimatic trends induced fluctuations in stream flows and dominated the development of the sedimentary deposits the process simulation approach serves as a quantitative means to explore the genesis of sedimentary architecture and its link to past climatic conditions and fault motion

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

modeling tracer transport at the made site the importance of heterogeneity 1 we examine three stochastic transport models of the macrodispersion experiment made site using high resolution conductivity fields derived from a new geostatistical interpretation of the flowmeter data evaluation of the spatial continuity of the hydraulic conductivity data revealed a hole effect structure indicating the occurrence of periodic structures i e clustered lenses or facies alternatively we examine geostatistical models based on indicator variables and found a similarity to bivariate gaussian properties tritium transport was simulated in kriged fields and in random fields generated using different geostatistical models at a grid spacing equal to the vertical support scale of the flowmeter measurements to explicitly represent small scale heterogeneity only those simulations obtained using the hole effect model resulted in a subset of realizations which reproduced the strong anomalous tracer spreading neglecting the hole effect structure of the spatial model in the gaussian simulations resulted in a reduced tailing of the tracer illustrating the importance of preferential flow on anomalous solute transport at the columbus aquifer furthermore we found that a multivariate gaussian random function is adequate to model the spatial distribution of hydraulic conductivity at the made site based on the results of the indicator transport simulations and the univariate and bivariate normality detected in the analysis of the flowmeter data we conclude that when small scale variability of hydraulic conductivity is correctly modeled at the flowmeter measurement support scale the ade is capable of reproducing the tracer spreading results suggest that the main contributor to the operational memory function used in previous successful mass transfer models is mostly a reflection of the suppressed spatial variation of hydraulic conductivity at the model scale

features of the f3 layer in the low latitude ionosphere at sunset the f 3 layer is a common feature within 10 degrees of the magnetic equatorial ionosphere in the daytime according to balan et al 1998 the f 3 layer occurs mainly during the morning noon period due to the combined effect of the upward e x b drift and the neutral wind that provides upward plasma drifts at and above the f 2 layer the f 3 layer occurrence rate is higher in summer and decreases with increasing solar activity in this study the characteristic of the sunset f 3 layer is first investigated using a solar cycle of ionosonde data 1995 2010 from the magnetic equatorial station at jicamarca and compared with the features derived from the four subtropical stations at sao luis fortaleza kwajalein and vanimo evidence shows that the local time distribution of the occurrence of the f 3 layer can extend to the postsunset time 1800 2100 local time the sunset f 3 layer has a strong seasonal dependence occurring mainly during the summertime unlike the daytime f 3 layer the occurrence of the sunset f 3 layer clearly increases and the virtual height of the bottom side of the f 3 layer statistically increases from 620 to 1000 km with increasing solar activity in addition the occurrence of the sunset f 3 layer at the other stations is much less than that at jicamarca these features of the dependence on the season solar activity and latitude are clearly related to the geomagnetic control of the evening prereversal enhancement of the equatorial zonal electric field and geomagnetic configuration

phosphate fractionation and spatial patterning in ancient ruins a case study from yucatan abstract as time passes phosphorus p in soils tends to become more tightly bound with minerals phosphate fractionation enables the measurement of loosely versus tightly bound p archaeologists have used p fractionation as a chronometric technique older soils should have greater proportions of p tightly bound with minerals research at chunchucmil a large maya ruin in yucatan mexico has used extractable p concentrations and other lines of evidence to investigate ancient uses of space because contemporary maya villagers use the land among the chunchucmil ruins in a number of ways and because the ancient land surfaces are neither sealed nor deeply buried we used p fractionation to determine whether geochemical signatures of activities such as gardening resulted from ancient or modern inhabitants the fractionation results at chunchucmil are unusual in comparison to studies from other sites furthermore there are strong correlations between the sum of p fractions and carbonate we discuss potential explanations for these patterns in p fractionation data these explanations consider local pedology differential length of ancient occupation and localized dumping of the byproducts of maize processing to examine the chemical signatures of maize processing specifically soaking maize in lime water contemporary samples of sediments and residues from this activity were analyzed our results suggest that dumping water from maize soaking provides a potential explanation for the ancient p patterns

dense nonaqueous phase liquid dnapl source zone characterization influence of hydraulic property correlation on predictions of dnapl infiltration and entrapment dnapl source zone characterization

first simultaneous observations of f3 layer and e b drift in indian sector and modeling 1 although the basic mechanism of an additional stratification of the daytime equatorial f region called the f3 layer has been explained two observational aspects that remain not so clear are its summer winter differences and simultaneous occurrences on either side of the geomagnetic equator in this paper we address these two aspects using simultaneous observations of the f3 layer and vertical e b drift velocity made for the first time in an indian station gadanki 6 5 n mag lat during the low solar activity period 2008 2009 and making model computations using the sheffield university plasmasphere ionosphere model the observations confirm the frequent occurrence of the f3 layer in summer months compared to winter months the observations also reveal the occasional occurrence of clear and distinct f3 layer in winter although such a layer is frequent in summer in addition a threshold vertical plasma velocity involving the e b drift and neutral wind and its time integrated value are found to be important for the formation of the f3 layer the model results qualitatively reproduce the observations and show that irrespective of season the formation of the f3 layer is centered on that side of the equator where the equatorward neutral wind reduces the downward field aligned flow of plasma and the latitude band of the layer can extend to the opposite hemisphere especially when the vertical plasma velocity is large

architecture of the sierra ladrones formation central new mexico depositional controls on the permeability correlation structure statistical models of hydrogeological heterogeneity are often used in aquifer and reservoir characterization the number of data required to estimate objectively the spatial correlation structure of permeability however is often prohibitive the objective of this study was to develop a better understanding of how information about depositional processes can be used to characterize hydrogeological heterogeneity an outcrop of the fluvial interfluvial sierra ladrones formation of new mexico was studied for this purpose on the basis of previous studies of paleogeography and our own field observations deposits of the sierra ladrones formation are interpreted as marginal ancestral rio grande flood plain and tributary deposits architectural elements were mapped over a 0 16 km sup 2 peninsular outcrop of pliocene pleistocene deposits of the central albuquerque basin geostatistical analysis of the architectural element map data indicates non orthogonal anisotropy in the horizontal direction the orientations of the strongest n30 degree w and weakest n90 degree e correlation correspond to the orientation of the tributary system and the ancestral rio grande flood plain respectively in the vertical direction the correlation structure exhibits exponential behavior corresponding to the average element thicknesses the results demonstrate that information about depositional environment can be used to help to quantify statistically subsurface heterogeneity 28 refs 9 figs 1 tab

magnetic conjugate observation of the f3 layer using the sealion ionosonde network 1 results from the meridional ionosonde network located in southeast asia sealion demonstrate the interesting nature of the f3 layer showing its generation mechanism ionograms obtained on 16 november 2004 and 31 march 2005 at chiang mai cmu geographic latitude 18 8 n geographic longitude 98 9 e and magnetic latitude 13 2 n chumphon cpn 10 7 n 99 4 e and 3 2 n and kototabang ktb 0 2 s 100 3 e and 10 1 s showed significant differences between cpn near the magnetic equator and cmu and ktb in the magnetic low latitude region the simultaneous magnetic conjugate observations of the f3 layer achieved using the sealion ionosonde network data showed clear dependences of the f3 layer on the magnetic latitude it is suggested that these magnetic latitude dependences of the f3 layer can be explained by considering the plasma diffusion effects along the magnetic field lines in the magnetic low latitude region

spatial variability in river sediments and its link with river channel geometry 1 this study explores the link between spatial variability within fluvial sedimentary strata and river channel geometry this link is then used to determine the macrodispersion coefficients for solute transport in groundwater flow in river deposits in doing that we combine concepts from sedimentology geostatistics and the stochastic lagrangian theory of subsurface transport it is proposed to analyze the spatial variability of river sediments in terms of transition probabilities the transition probabilities can be determined from the averages and variances of the lengths of stratasets and their volumetric fractions using concepts developed by carle and fogg 1996 and ritzi 2000 strataset length scales are shown to correlate well with the geometry of the river channel and its bed forms and can be determined indirectly from aerial photogrammetry and more directly through surface ground penetrating radar surveys stratal dimensions can also be related using lagrangian transport analysis to macrodispersivity of subsurface transport this allows relationships between the geometry of river channels and subsurface transport parameters of associated fluvial deposits for demonstration the longitudinal macrodispersivity in a compound bar deposit in the gravelly braided sagavanirktok river was investigated

numerical estimation of effective permeability in sand shale formations a numerical approach is used to estimate effective permeability in sand shale formations under steady state uniform flow conditions permeability is modeled as a binary second order stationary random function taking on two possible values kss and ksh in sandstone and shale respectively this model is realistic since experience with sandstone reservoirs has shown that randomly dispersed low permeability shales are the single dominant heterogeneity affecting flow behavior the cases of both spatially correlated and uncorrelated permeabilities are considered for the case of spatially correlated permeability an autocovariance model was fitted to data from the assakao fluvial sandstone which outcrops in the tassili region of the central sahara the turning bands method was used to simulate the spatially correlated permeabilities of blocks discretizing the flow field effective permeability was found to depend on the shale volume fraction the spatial covariance structure and the dimensionality of the flow system existing analytical methods for estimating effective permeability in a two phase medium are found to be inaccurate when compared to numerical results or unapplicable to stratified environments in addition to providing a check of analytical work the numerical approach is found to be a useful tool for exploring the effects of reservoir heterogeneity on flow behavior in a qualitative sense

evolution of the northern santa cruz mountains by advection of crust past a san andreas fault bend the late quaternary marine terraces near santa cruz california reflect uplift associated with the nearby restraining bend on the san andreas fault excellent correspondence of the coseismic vertical displacement field caused by the 17 october 1989 magnitude 7 1 loma prieta earthquake and the present elevations of these terraces allows calculation of maximum long term uplift rates 1 to 2 kilometers west of the san andreas fault of 0 8 millimeters per year over several million years this uplift in concert with the right lateral translation of the resulting topography and with continual attack by geomorphic processes can account for the general topography of the northern santa cruz mountains

an approach to estimating hydraulic conductivity spatial correlation scales using geological characteristics the estimation of hydraulic conductivity and other correlation scales by traditional geostatistical methods requires a large number of field measurements at appropriate horizontal and vertical spacings in order to extend the application of stochastic subsurface hydrology analysis to situations where such data are limited we propose an approach to correlation scale estimation that incorporates geological mapping regions of the formation with hydraulic conductivity values above or below some specified cutoff value are mapped and their dimensions are related to the correlation scale by means of threshold crossing theory

identification of activity areas by multi element characterization of sediments from modern and archaeological house floors using inductively coupled plasma atomic emission spectroscopy abstract a pilot study on the chemical analysis of earthen house floors using both modern and archaeological localities was undertaken to determine the degree to which activities leave detectable chemical residues and whether these residues are preserved in archaeological contexts the goals were to develop techniques for the identification and interpretation of activity areas in archaeological structures and to determine which elements serve to distinguish activities one modern structure from oaxaca mexico and two archaeological house floors from british columbia canada and oaxaca mexico were studied soil samples were collected from floors at all three sites and analysed by inductively coupled plasma atomic emission spectroscopy icp aes for al ba ca fe k mg mn na p sr ti and zn preliminary results show that activity areas in the modern house compound can readily be distinguished on the basis of chemical residues in soils that archaeological features are chemically distinct from natural soils and that features such as floors and hearths can be distinguished from each other and from the natural prehistoric ground surface multi element characterization by icp aes offers an advantage over traditional single element analysis by yielding more useful data for less effort expense and time

multi element soil prospection aiding geophysical and archaeological survey on an archaeological site in suburban sagalassos sw turkey in order to take full advantage of the archaeological information contained within buried archaeological sites it is important to apply an integrative approach combining complementary prospection methods in this study geochemical prospection data are combined with archaeological and geophysical survey results on an unexcavated site in suburban sagalassos sw turkey with the aim of obtaining better insights into the structural shapes and past functionalities of the area spatial and multivariate statistical analyses of the chemical data reveal anomalies of k p and zn on a location where archaeological and geophysical results suggest the presence of ceramic producing kilns these elemental enrichments are thought to result from burning wood or dung as fuel for the detected kilns in addition local anomalies of co cr fe mg mn and ni were found to reflect the working and storage of ophiolitic clays employed as a raw material for ceramic production radiocarbon dating of charcoal in a 2 5 m deep drill core in this zone provides ages between ad 120 and 350 at depths of 50 and 60 cm al as ba ca na sr ti and pb are considered geogenic elements in this study the present study supports the theory that geochemical prospection holds potential as a surveying technique as it was found that chemical data facilitate the interpretation of structures detected by geophysical and archaeological methods thereby creating an extra dimension to the interpretation of survey data the results further argue in favour of using strong acid extractions and the consideration of a large suite of elements when applying chemical soil survey as an archaeological prospection technique and highlight the importance of considering site lithology multivariate statistics proved to be invaluable in distinguishing anthropogenic from lithological soil patterns

equatorial plasma fountain and its effects over three locations evidence for an additional layer the f 3 layer the equatorial plasma fountain and equatorial anomaly in the ionospheres over jicamarca 77 w trivandrum 77 e and fortaleza 38 w are presented using the sheffield university plasmasphere ionosphere model under magnetically quiet equinoctial conditions at high solar activity the daytime plasma fountain and its effects in the regions outside the fountain lead to the formation of an additional layer the f3 layer at latitudes within about plus or minus 10 of the magnetic equator in each ionosphere the maximum plasma concentration of the f3 layer which occurs at about 550 km altitude becomes greater than that of the f2 layer for a short period of time before noon when the vertical e b drift is large within the f3 layer the plasma temperature decreases by as much as 100 k the ionograms recorded at fortaleza on january 15 1995 provide observational evidence for the development and decay of an f3 layer before noon the neutral wind which causes large north south asymmetries in the plasma fountain in each ionosphere during both daytime and nighttime becomes least effective during the prereversal strengthening of the upward drift during this time the plasma fountain is symmetrical with respect to the magnetic equator and rises to over 1200 km altitude at the equator with accompanying plasma density depletions in the bottomside of the underlying f region the north south asymmetries of the equatorial plasma fountain and equatorial anomaly are more strongly dependent upon the displacement of the geomagnetic and geographic equators jicamarca and trivandrum than on the magnetic declination angle fortaleza

the story in the floors chemical signatures of ancient and modern maya activities at aguateca guatemala abstract soil chemical analysis has been one of the most active and promising areas among the recent innovations in household archaeology ancient inhabitants unintentionally left chemical imprints of daily activities providing important clues as to past practices and space use which are difficult to judge from artifactual data alone soil chemical testing in the maya region is particularly promising given the highly calcareous nature of the soils derived from the carbonate geology of the region as calcium ions and soil alkalinity render phosphorous iron and other metallic ions insoluble this paper reports the results of soil chemical analysis of modern and ancient residential structures at the archaeological park of aguateca guatemala an ethnoarchaeological study of the guards living quarters and archaeological data from rapidly abandoned classic period residences provided opportunities to refine an understanding of the relationship between human activities and soil chemical signatures both cases exhibited good correlations of high phosphorous concentrations in soils with food processing consumption and disposal high levels of heavy metals in the modern structures probably derived from the filing of machetes and the disposal of flashlight batteries whereas the use of mineral pigments and craft activities appear to have contributed to the concentrations of these elements in archaeological contexts

altitudinal dependence of evening equatorial f region vertical plasma drifts we use jicamarca incoherent scatter radar measurements to study for the first time the altitudinal variations of late afternoon and early night equatorial f region vertical plasma drifts we also present the initial vertical drift measurements over the altitudinal range from about 200 to 2000 km these data show that the afternoon drifts decrease weakly with altitude near their evening prereversal enhancements the vertical drifts generally increase with altitude below about the f layer peak decrease with height near the f layer peak and above and are nearly height independent in the solar flux dependent topside ionosphere the transition altitudes from height decreasing to height independent evening upward drifts decrease with altitude from solar maximum to solar minimum after their reversal to downward the vertical drifts do not change much with height the altitudinal dependence of the evening vertical drifts has large day to day variability and is closely related to the time dependence of the zonal drifts as expected from the curl free electric field condition

surface expression of the chicxulub crater analyses of geomorphic soil and topographic data from the northern yucatan peninsula mexico confirm that the buried chicxulub impact crater has a distinct surface expression and that carbonate sedimentation throughout the cenozoic has been influenced by the crater late tertiary sedimentation was mostly restricted to the region within the buried crater and a semicircular moat existed until at least pliocene time the topographic expression of the crater is a series of features concentric with the crater the most prominent is an approximately 83 km radius trough or moat containing sinkholes the cenote ring early tertiary surfaces rise abruptly outside the moat and form a stepped topography with an outer trough and ridge crest at radii of approximately 103 and approximately 129 km respectively two discontinuous troughs lie within the moat at radii of approximately 41 and approximately 62 km the low ridge between the inner troughs corresponds to the buried peak ring the moat corresponds to the outer edge of the crater floor demarcated by a major ring fault the outer trough and the approximately 62 km radius inner trough also mark buried ring faults the ridge crest corresponds to the topographic rim of the crater as modified by postimpact processes these interpretations support previous findings that the principal impact basin has a diameter of approximately 180 km but concentric low relief slumping extends well beyond this diameter and the eroded crater rim may extend to a diameter of approximately 260 km

hydrostratigraphic interpretation using indicator geostatistics in this paper we describe an approach that uses indicator geostatistics to interpret qualitative borehole logs and compute experimental variograms for complex alluvial sediments borehole descriptions are first transformed into binary indicator values based on inferred relative permeability from the borehole descriptions the resulting indicator data can then be used to compute variograms and construct three dimensional variogram models the ranges of computed indicator variograms for a groundwater contamination site in santa clara valley california are very sensitive to the orientation of the search plane these variograms are consistent with known stratigraphie features and describe the spatial structure of deposits from different depositional environments indicator kriging weighs all the available data on the basis of a three dimensional anisotropic variogram model and provides an estimate of uncertainty in the hydrostratigraphic correlation kriged indicator values represent probabilities that sediments at a specific location fall into one of two indicator categories the location of the 0 5 indicator contour is approximately the boundary between high and low permeability sediments that might be constructed in a geologic cross section

dense nonaqueous phase liquid dnapl source zone characterization influence of hydraulic property correlation on predictions of dnapl infiltration and entrapment 1 the influence of aquifer property correlation on multiphase fluid migration and entrapment was explored through the use of correlated and uncorrelated porosity permeability and capillary pressure saturation pc sat parameter fields in a cross sectional numerical multiphase flow model data collected from core samples in a nonuniform sandy aquifer were used to generate three dimensional aquifer parameter fields porosity was assumed to be uniform or simulated using sequential gaussian simulation sgs permeability k was modeled independently of porosity using sgs as well as simulated geostatistical indicator classes derived from measured grain size distribution curves retention characteristics were assigned employing leverett scaling of a representative pc sat curve to the geostatistical k fields or alternatively on the basis of simulated indicator classes and porosity values ensemble dense nonaqueous phase liquid dnapl infiltration and entrapment behavior for a hypothetical tetrachloroethylene pce spill was simulated in four sets of two dimensional profiles extracted from these realizations comparisons of saturation profiles and spatial moments from point source dnapl infiltration simulations suggest that choices involving the geostatistical algorithm used to model k and the incorporation of variable versus uniform porosity have a smaller influence than choices involving the scaling of capillary retention properties to k from these simulations it is apparent that the degree of spatial correlation in pc sat parameters exerts a controlling influence on predicted dnapl spreading and redistribution in saturated aquifers the resultant distribution of mass within a dnapl source zone will have implications for dnapl recovery and subsequent mass fluxes in remediation operations

field study of dispersion in a heterogeneous aquifer 3 geostatistical analysis of hydraulic conductivity observations of the spatial variability of hydraulic conductivity at a tracer test site located at columbus air force base in mississippi are presented direct measurements of hydraulic conductivity of the heterogeneous alluvial aquifer at the site were made using borehole flowmeter logging slug tests and a laboratory permeameter to test undisturbed soil cores indirect methods estimating hydraulic conductivity were also evaluated including soil grain size analyses surface geophysical surveys and mapping of sediment facies the spatial covariance of the 2187 hydraulic conductivity values obtained with the borehole flowmeter method was examined the log hydraulic conductivity variance ln2k and the horizontal and vertical correlation scales h and v of 4 5 12 8 m and 1 6 m respectively were estimated assuming second order stationarity of the conductivity field the covariance parameters are uncertain with bounding values that are 24 76 above or below the estimate covariance parameters estimated with more limited nonflowmeter data were within the same magnitude as those obtained using the extensive flowmeter data suggesting that data from a variety of methods may be used to provide approximate values of the autocovariance parameters nonstationarity of the ln k field was examined by removing three dimensional polynomial trend surfaces and calculating variograms of the residuals significantly lower estimates for ln2k h and v of 2 7 4 8 m and 0 8 m respectively were obtained from the third order log conductivity residuals after trend removal the bounding parameter values differ 15 44 from the estimated values accounting for unsteady flow and the uncertainty in the covariance parameters of the third order log conductivity residuals the calculated longitudinal and horizontal transverse macrodispersivities ranged from 1 5 m to 1 8 m and 0 3 m to 0 6 m respectively

parameters in the use of pxrf for archaeological site prospection a case study at the reaume fort site central minnesota abstract field portable hand held x ray fluorescence pxrf analyzers have been characterized as potentially useful for archaeological site prospection but little has been published on the parameters of their use in this manner the purpose of this study is to explore whether the variability of surface geochemistry as characterized with a pxrf analyzer corresponds with subsurface archaeological features at a site subsequently excavated and what conditions influence the success of this endeavor including feature depths soil moisture and sample processing a 520 m 2 within site area was systematically surveyed on a 2 m interval within which several types of archaeological features were excavated chimney bases wall trenches and a bonebed of faunal waste taking readings in situ and collecting samples for ex situ testing undried dried but not powdered and dried powdered the four different tests of each grid location analyzed through univariate and multivariate tests showed that the pxrf surface data does correspond with some types of subsurface features when those features are very shallow within 5 cm of surface level and are associated with clayey fills further the data from the subsurface samples provides excellent distinction of feature fills from other sediments regardless of sample preparation in situ surface survey with pxrf analyzers may however be adequate for sites with a thorough baseline geochemical database

deciphering the inorganic chemical record of ancient human activity using icp ms a reconnaissance study of late classic soil floors at cancuen guatemala abstract inorganic chemical analysis of soil floors using inductively coupled plasma mass spectrometry icp ms was undertaken to provide information on the nature and location of past human activity in the ancient maya city of cancuen guatemala the use of icp ms to detect trace and ultra trace elemental enrichment of two excavated soil floors from the late classic period is the first study of its kind in mesoamerican archaeology geochemical background of the site was established by the analysis of palaeosols and nearby undisturbed off site soil profiles robust statistical methods used in the study clearly distinguished the level of anthropogenic enrichment across the former floors many elements measured showed only minor departures 10 20 from the site s background soil chemistry the greatest levels of elemental enrichment were detected in the rare earth elements mercury and gold the latter is of particular interest considering the consensus that gold was absent from the world of the classic period maya comparisons of the spatial pattern of mercury enrichment with lithic and archaeological data show strong linkages to past industrial and ritual activities elevated rare earth element concentrations were recorded broadly across both soil floors and are considered to be related to concentrated human occupation in antiquity

observations of daytime f2 layer stratification under the southern crest of the equatorial ionization anomaly region 1 ionospheric vertical sounding observations are being carried out at sao jose dos campos 23 2 s 45 9 w dip latitude 17 6 s brazil under the southern crest of the equatorial ionization anomaly eia since august 2000 in this paper we present and discuss the observations of daytime f2 layer stratification near the crest of eia for the first time under magnetically quiet high solar activity conditions three examples and a year of statistics are presented the f2 layer stratification and f3 layer were observed between 10 40 and 11 45 ut on 31 december 2000 between 13 30 and 14 30 ut on 1 january 2001 and between 13 15 and 15 15 ut on 11 february 2001 the statistics during september 2000 to august 2001 shows that the f3 layer occurs only for 66 days 18 occurrence and it occurs only during september february spring summer with maximum occurrence in september october and longest duration in february the f2 layer stratification seems to be associated with gravity waves gws which have periods of about 30 60 min downward phase velocities of about 60 140 m s and vertical wavelengths of about 200 500 km the presence of powerful gravity waves in a vertically extended f layer seems to stratify the f2 layer and produce the f3 layer because the stratifications are observed during geomagnetically quiet periods the source of the gravity waves are most likely to be associated with local tropospheric disturbances and not with high latitude disturbances

the geoarchaeological significance and spatial variability of a range of physical and chemical soil properties from a former habitation site isle of skye of the 34 major and trace elements investigated in this study enrichments of k th rb and to a lesser extent cs were associated with former habitation of the area whilst high levels of sr and to a lesser extent ca were associated with the adjacent field area this latter enrichment is thought to represent additions of shell sand and or bone and fish refuse phosphorus is a less reliable indicator of human habitation than k rb and th possibly because p enrichment may be caused by additions of animal manure as well as by human habitation of an area vanadium co zn pb ni ga sc mg cu and u all indicated negligible on site enrichment whilst cr and organic matter content were found to be depleted in the on site soils relative to the control samples consideration of the degree of variability in the soil parameters investigated has implications for the bulk or composite sampling of soils over sites of former habitation

physical mechanism and statistics of occurrence of an additional layer in the equatorial ionosphere a physical mechanism and the location and latitudinal extent of an additional layer called the f3 layer that exists in the equatorial ionosphere are presented a statistical analysis of the occurrence of the layer recorded at the equatorial station fortaleza 4 s 38 w dip 9 s in brazil is also presented the f3 layer forms during the morning noon period in that equatorial region where the combined effect of the upward e b drift and neutral wind provides a vertically upward plasma drift velocity at altitudes near and above the f2 peak this velocity causes the f2 peak to drift upward and form the f3 layer while the normal f2 layer develops at lower altitudes through the usual photochemical and dynamical effects of the equatorial region the peak electron density of the f3 layer can exceed that of the f2 layer the f3 layer is predicted to be distinct on the summer side of the geomagnetic equator during periods of low solar activity and to become less distinct as the solar activity increases ionograms recorded at fortaleza in 1995 show the existence of an f3 layer on 49 of the days with the occurrence being most frequent 75 and distinct in summer as expected during summer the layer occurs earlier and lasts longer compared to the other seasons on the average the layer occurs at around 0930 lt and lasts for about 3 hours the altitude of the layer is also high in summer with the mean peak virtual height being about 570 km however the critical frequency of the layer f0f3 exceeds that of the f2 layer f0f2 by the largest amounts in winter and equinox f0f3 exceeds f0f2 by a yearly average of about 1 3 mhz

ancient maya impacts on the earth s surface an early anthropocene analog abstract the measure of the mayacene a microcosm of the early anthropocene that occurred from c 3000 to 1000 bp comes from multiple late quaternary paleoenvironmental records we synthesized the evidence for maya impacts on climate vegetation hydrology and the lithosphere from studies of soils lakes floodplains wetlands and other ecosystems maya civilization had likely altered local to regional ecosystems and hydrology by the preclassic period 3000 1700 bp but these impacts waned by 1000 bp they altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs wetland fields and canals terraces field ridges and temples although there is abundant evidence that indicates the maya altered their forests even at the large urban complex of tikal as much as 40 of the forest remained intact through the classic period existing forests are still influenced by ancient maya forest gardening particularly by the large expanses of ancient stone structures terraces and wetland fields that form their substrates a few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the classic period 1700 1100 bp a much larger body of research documents the maya impacts on hydrology in the form of dams reservoirs canals eroded soils and urban design for runoff another metric of the mayacene are paleosols which contain chemical evidence for human occupation revealed by high phosphorus concentrations and carbon isotope ratios of c 4 species like maize in the c 3 dominated tropical forest ecosystem paleosol sequences exhibit maya clays a facies that reflects a glut of rapidly eroded sediments that overlie pre maya paleosols this stratigraphy is conspicuous in many dated soil profiles and marks the large scale maya transformation of the landscape in the preclassic and classic periods some of these also have increased phosphorous and carbon isotope evidence of c 4 species we synthesize and provide new evidence of maya period soil strata that show elevated carbon isotope ratios 13 c indicating the presence of c 4 species in typical agricultural sites this is often the case in ancient maya wetland systems which also have abundant evidence for the presence of several other economic plant species the mayacene of c 3000 to 1000 bp was thus a patchwork of cities villages roads urban heat islands intensive and extensive farmsteads forests and orchards today forests and wetlands cover much of the maya area but like so many places these are now under the onslaught of the deforestation draining and plowing of the present anthropocene

characterization of alluvial hydrostratigraphy with indicator semivariograms current trends in hydrogeology seek to enlist sedimentary concepts in the interpretation of permeability structures however depositional models tend to account insufficiently for heterogeneities caused by complex controls on sediment preservation conversely geostatistical methods empirically describe both random and structured attributes this paper presents comparative indicator semivariograms for proximal medial and distal alluvial fan settings in santa clara valley california hydrostratigraphic structures revealed by a binary textural indicator are consistent within each setting yet differ from one setting to another in the bedrock bounded proximal setting buried channel deposits exhibit a small nugget effect and a zonal anisotropy with correlation ranges up to 900 m in the distal setting deposits display relatively weak hydrostratigraphic correlation with a relative nugget effect of 50 and a correlation range of 80 m in the medial setting the correlation range is similar to the proximal area but with a large nugget effect similar to the distal area

transport modeling in heterogeneous aquifers 1 statistical description and numerical generation of gravel deposits transport of solutes in groundwater is decisively influenced by the heterogeneity of the aquifer the goal of the present work is the numerical generation of synthetic heterogeneous aquifer models based on a statistical description of heterogeneities in gravel aquifers large unweathered outcrops in several gravel pits in northeastern switzerland were investigated in this context on the basis of sedimentological observations it was possible to specify distinct sedimentary structures appearing as lenses or layers all structures have been identified in each of the investigated outcrops by inspecting and analyzing photographs of the outcrops it was possible to estimate the probability density functions pdf of the geometrical attributes of the sedimentary structures disturbed and undisturbed samples were taken from these structures to estimate the pdf of their hydraulic properties that is the hydraulic conductivity and the porosity the information obtained is used to generate distinct numerical realizations by unconditional stochastic simulation of synthetic aquifers having the same statistical properties with respect to hydraulic conductivity and porosity as the investigated deposits

comparing statistical models of physical heterogeneity in buried valley aquifers the hypothesis that physical heterogeneity has similarities in separate aquifers created by similar depositional environments is tested by comparing statistical characteristics of facies assemblages the comparisons are made for a number of data rich sites in two buried valley aquifers in the north american midcontinent the white river aquifer in indiana and the miami valley aquifer in ohio these were proglacial valleys that directed drainage away from quaternary ice margins and were filled with glaciofluvial sediments predominantly sand and gravel s lithofacies with interbedded mud and diamicton m lithofacies at scales encompassing assemblages of both lithofacies m and s permeability is strongly bimodal we find that it is useful to compare statistics that characterize the proportions geometry and spatial distribution of each facies the results give rise to a general model for heterogeneity in valley fill sediments along the proglacial sluiceway in both aquifers the proportion of facies m is 15 the mean thickness of facies m is 3 5 m and of the order of 10 m for facies s the coefficient of variation in thickness for either facies is of the order of 1 with thickness ranging over orders of magnitude correspondingly the vertical autotransition probabilities are exponential and they are relatively symmetric with effective range of the order of 10 m the lateral facies lengths are indicated to vary over orders of magnitude and to be multimodally distributed with mean lengths of the order of 102 m effective range in correlation structure of the order of 103 m and lateral anisotropy ratio 2 there is some variation in how the facies m are vertically embedded within the facies s the white river aquifer and areas in the miami aquifer have facies proportions relatively stationary with elevation in other areas of the miami there are near horizontal zones having relatively higher or lower proportions however such variations on the general model give rise to similar statistics for mass transport within the context of a relevant remediation problem and thus would lead to a similar conclusion or decision thus one general model is applicable to both aquifers in this context in a broader sense we have illustrated a method by which other examples developed from data rich sites can be compared

elemental prospecting and geoarchaeology in turkey and mexico abstract understanding past human impacts on soils requires many forms of evidence including elemental chemistry human activities leave traces of different elements distinguishing activity sites since the 1990s more scholars have used a full range of analytical techniques including inductively coupled plasma atomic emission spectroscopy icp aes and inductively coupled plasma mass spectroscopy icp ms also since that time the near singular focus on phosphate as a prime indicator of human activity has broadened to include a large suite of elemental indicators aided by the emergence of many tools and techniques such as icp this paper focuses on the elemental chemistry of sediments at two archaeology sites chunchucmil mexico and kinet turkey the purpose of this study is to understand how certain elements correlate with each other and vary by space and time at different archaeology sites and as an important methodological consideration how different solvents affect icp aes analyses in other words does human activity significantly alter the elemental chemistry of a site and if so is this in a systematic way or does it vary geographically and are these chemical signatures of human activity hidden or highlighted by different icp methods we examined soil chemistry by types of geomorphic and archaeological location contexts e g floors natural deposits walls streets and by age of deposit e g hellenistic iron age to detect differences in soil chemistry signatures associated with them and for regional variations in icp methods effectiveness our analyses revealed detectable differences between natural and anthropogenic deposits site types eras and large differences between methods high amounts of lead were correlated with streets and rooms in the medieval and bronze periods in kinet turkey and natural deposits had lower levels of cadmium and mercury icp np treatments revealed higher detection levels of most elements than did icp dt treatments in chunchucmil mexico

geochemical evidence for african dust inputs to soils of western atlantic islands barbados the bahamas and florida 1 we studied soils on high purity limestones of quaternary age on the western atlantic ocean islands of barbados the florida keys and the bahamas potential soil parent materials in this region external to the carbonate substrate include volcanic ash from the island of st vincent near barbados volcanic ash from the islands of dominica and st lucia somewhat farther from barbados the fine grained component of distal loess from the lower mississippi river valley and wind transported dust from africa these four parent materials can be differentiated using trace elements sc cr th and zr and rare earth elements that have minimal mobility in the soil forming environment barbados soils have compositions that indicate a complex derivation volcanic ash from the island of st vincent appears to have been the most important influence but african dust is a significant contributor and even mississippi river valley loess may be a very minor contributor to barbados soils soils on the florida keys and islands in the bahamas appear to have developed mostly from african dust but mississippi river valley loess may be a significant contributor our results indicate that inputs of african dust are more important to the genesis of soils on islands in the western atlantic ocean than previously supposed we hypothesize that african dust may also be a major contributor to soils on other islands of the caribbean and to soils in northern south america central america mexico and the southeastern united states dust inputs to subtropical and tropical soils in this region increase both nutrient holding capacity and nutrient status and thus may be critical in sustaining vegetation

global characteristics of occurrence of an additional layer in the ionosphere observed by cosmic formosat 3 global observations of electron density profile edp from the cosmic formosat 3 satellites were used to investigate for the first time the additional stratification of the f2 layer over the equatorial ionosphere on a global scale which is called f3 layer the f3 layer in edp was recognized through the altitude differential profile featured by two maxima existing from 220 km to the peak height of the electron density there were similar to 9 400 cases of f3 layer selected out of similar to 448 000 occultation events at low and equatorial areas during the period of april 2006 september 2010 statistical results show that the highest occurrence of f3 layer appears at dip latitude 7 similar to 8 degrees 7 similar to 8 degrees for northern southern hemisphere and is more pronounced during summer months at 10 00 14 00 lt the occurrence also has a clear longitude dependence during boreal summer with relatively higher occurrence at 80 similar to 100 degrees 20 similar to 20 degrees 80 similar to 120 degrees and 160 similar to 170 degrees longitudes that is possibly associated with the wavenumber 3 diurnal tide de3 the results support the principle of the f3 layer proposed by balan et al 1998 which in turn validate the accuracy of the retrieval of the cosmic edp data citation zhao b w wan x yue l liu z ren m he and j liu 2011 global characteristics of occurrence of an additional layer in the ionosphere observed by cosmic formosat 3 geophys res lett 38 l02101 doi 10 1029 2010gl045744

human and natural impacts on fluvial and karst depressions of the maya lowlands abstract this paper begins to differentiate the major drivers and chronology of erosion and aggradation in the fluvial and fluviokarst landscapes of the southern and central maya lowlands we synthesize past research on erosion and aggradation and add new data from water soils radiocarbon dating and archaeology to study the quantity timing and causes of aggradation in regional landscape depressions geomorphic findings come from many excavations across a landscape gradient from upland valleys karst sinks and fans into the coastal plain floodplains and depressions findings from water chemistry show that sources in the uplands have low quantities of dissolved ions but water in the coastal plains has high amounts of dissolved ions often nearly saturated in calcium and sulfate we found significant geomorphic complexity in the general trends in upland karst sinks in a few instances sediments preserve late pleistocene paleosols buried 2 3 m though many more have distinct middle to late holocene paleosols buried 1 2 m after c 2300 bp maya early to late preclassic from 2300 1100 bp late preclassic to classic periods the landscape aggraded from five main mechanisms river flooding climatic instability accelerated erosion ancient maya landscape manipulation and gypsum precipitation from a rise in a water table nearly saturated in calcium and sulfate ions evidence exists for two or three high magnitude floods possibly driven by hurricanes moreover lake core and geophysical studies from the peten lakes region have shown high rates of deposition of silicate clays maya clays starting and peaking during the maya preclassic and continuing to be high through the late classic the main driver on upland karst depressions the peten lakes upland valleys and fans was accelerated soil erosion but water table rise probably driven by sea level rise was the main driver on the wetlands of the coastal plain because the aggraded sediments here are dominantly composed of gypsum precipitated from the groundwater this latter mechanism represents a little recognized mechanism of aggradation over a large region these large scale environmental changes occurred during periods of intensive ancient maya land use and climatic instability both of which may have contributed to erosion by increasing runoff despite these geomorphic changes ancient maya farmers adapted in several key cases