structure and hydrology of mounds of the imported fire ants in the southeastern united states imported fire ants comprise two introduced species which build large mounds at high densities throughout the southeastern united states they represent a new soil forming factor for these soils a study was conducted to quantify the channel network geometry clod density aggregate stability and micromorphology of the mounds on three texturally different soils and examine the moisture relationships in the mounds the channels averaged 0 6 cm wide in mounds on a sandy loam and a silt loam and 1 0 cm wide in a mound on a clay soil channels occupied 39 of the horizontal cross sectional area in the mound on the sandy loam and 55 in the mounds on the silt loam and the clay the interchannel matrix of the mound assembled by the ants consists of a porous bridged pellet framework which is separated from the channels by a thin 1 mm thick semi coherent lining at the exterior of the mound this lining forms the underside of the crust of the mound which is only a few millimeters thick the aggregates created by the ants do not differ significantly 0 05 in bulk density or aggregate stability from those of the undisturbed topsoil with the exception of aggregates from the crust of the mound which are up to 38 less dense and up to 82 less stable than the adjacent soil aggregates the fragile crust allows more infiltration than the surrounding soil moisture contents are up to 170 greater in the mound than in the adjacent soil shortly after rainfall infiltrating water rapidly drains from the mound and can be stored in the channels below the mound as indicated by the occurrence of free water below mounds at 120 81 and 46 cm deep while no free water was present in the adjacent pedons the mound dries quickly to moisture contents as much as 82 lower than those of adjacent pedons as a result of this rapid drainage as colonies relocate their mounds over time entire landscapes may be exposed to the greater leaching of the pedogenic regime of the mound and soils may inherit new macropores and soil aggregates

sources of spatial complexity in two coastal plain soil landscapes abstract the spatial pattern of soils and soil properties in soil landscapes is considered here as a function of 1 systematic variation along catenas or associated with spatial patterns of soil forming factors and 2 local pseudo random variations associated with local disturbances or small unobserved variations in soil forming factors the problem is approached at two study sites in the u s atlantic coastal plain using algebraic graph theory and the spectral radius of the soil adjacency matrix as a measure of complexity the matrix is constructed based on the observed spatial contiguity of soil taxa and soil factor sequences sfs are defined for each site based on systematic soil variation associated with variations in parent material topography sandy surface thicknesses and secondary podzolization the spectral radii of the networks described by the adjacency graphs are compared to those associated with the maximum for a graph of the same size and the maximum associated with control entirely by variations in soil forming factors at the clayroot study site which is entirely cropland complexity of the adjacency matrix is less than the maximum that could be accounted for by the four identified sfs due to redundant information in the sfs the littlefield site by contrast has a spectral radius greater than here where about half the site is forested the contingent variation is likely associated with effects of individual trees on soil morphology the utility of the adjacency analysis is in identifying whether soil heterogeneity is likely associated with sfs or with contingent factors not captured in sfs

application of osl single aliquot and single grain dating to quartz from anthropogenic soil profiles in the se united states abstract reduced luminescence intensity in soils is a widespread phenomenon but is not understood we examine the distributions of equivalent dose d e values of quartz from surface and buried soils from earthen mounds in louisiana where pedoturbation is the likely cause of luminescence resetting we first investigated the effectiveness of optical bleaching in surface samples similar in composition and environment to those at depth resulting d e distributions from the top 10 cm of the topsoils approach 0 gy the concentration of zero age grains decreases rapidly with depth paleosol ages based on low values of the d e distribution demonstrate good agreement with previously published ages we propose a three zone model for the explanation of surface bleaching in which the soil surface is continuously stressed and loaded by subsurface turbation mechanisms creating surface relief surface relief is reduced by subaerial impact and transport forces causing disaggregation and single grain dispersion this results in a surface bleaching zone where soil particles and topography are in constant transition suggesting that many soils may offer frequent and thorough presentation of mineral grains to surface insolation and thus high concentrations of zero dose grains

occurrence characteristics and influential factors of movable fluids in pores with different structures of chang 63 reservoir huaqing oilfield ordos basin china abstract exploration and development of chang 63 reservoir in the huaqing oilfield ordos basin is challenging because of the complex geological features including strong heterogeneity complicated microscopic pore structures low saturation of movable fluids and distinct fluid distribution characteristics confronted with this challenge this study used the nuclear magnetic resonance nmr technique to quantitatively evaluate the movable fluids in pores with different structures moreover microscopic experiments were conducted to analyze the occurrence characteristics and influential factors of movable fluids in pores with different structures including conventional physical property analysis image porosity measurement casting thin section observation sem analysis high pressure mercury intrusion testing and constant pressure mercury intrusion testing the results showed that gray and grayish brown lithic feldspar sandstones were the dominant types of sandstone residual intergranular pores and feldspar dissolved pores were the main pore types with unevenly distributed pore throat radii among which small pores and micropores were primary four types of pore structures could be divided according to comprehensive analysis of capillary pressure curves namely types i ii iii and iv and they were featured by movable fluids with distinct occurrence characteristics in them reservoir permeability was well correlated with movable fluid saturation multiple factors were demonstrated to influence the movable fluid saturation in pores with different structures including pore throat radius pore throat radius ratio sorting coefficient effective pore and throat volume maximum mercury saturation in pores and throats and interstitial clay minerals generally good physical properties led to larger variation of movable fluid saturation among them effective pore throat radius and pore throat radius ratio were the dominant factors effective pore and throat volume as well as sorting coefficient had some degree of influence and maximum mercury saturation and physical properties had little effect on the movable fluid saturation

slope channel linkage and sediment delivery on north carolina coastal plain cropland this paper presents the results of field measurements conducted in a small 19 4 ha agricultural basin on the north carolina coastal plain the overall objective of the study is to determine the magnitude of soil erosion and sediment delivery as a result of storm runoff the results suggest that erosion in the region is more rapid and extensive than previously thought fields at the site are experiencing accelerated soil loss with rates often comparable to those of the southeastern piedmont a region long recognized as having rapid and problematic soil loss this casts doubt on some assessments of the coastal plain as being a stable non eroding landscape however much of the soil mobilized is redistributed and stored within the watershed with only a small portion of the soil eroded from slopes leaving the basin on an event time frame copyright 2002 john wiley sons ltd

age and correlation of emerged pliocene and pleistocene deposits u s atlantic coastal plain abstract paleontologic and paleomagnetic investigations were conducted on several hundred pliocene and pleistocene marine samples from five regions of the emerged atlantic coastal plain 1 the delmarva peninsula 2 eastern virginia 3 central and northern north carolina 4 southern north carolina and northeastern south carolina and 5 the charleston area south carolina molluscan and ostracode interval and assemblage zonations which are the primary means of regional correlation have been calibrated using planktic biochronologic paleomagnetic radiometric and amino acid recemization data these multiple dating criteria were used to determine the age and where possible the duration of marine transgressive regressive sequences a correlation chart illustrates the age relationships of 27 formations from five regions one important conclusion is some of the yorktown formation of virginia and north carolina including the duplin formation and some of the raysor of south carolina are late pliocene in age the late pliocene chowan river formation of north carolina is older than the early pleistocene waccamaw formation of south carolina which in turn may be older than the james city formation of north carolina during the last 1 0 million years multiple marine transgressions occurred in each region but the age of these middle and late pleistocene formations often may differ from one area to the next a significant result of the study is the evidence for the lack of time equivalence of formations in the five different regions that is the sequence of marine transgressions in one region does not necessarily correspond to that in another this appears to be the result of differing subsidence and uplift histories the patchiness of the depositional record and the limitations of the dating techniques in light of the rapidity and frequency of sea level fluctuations

divergent evolution and the spatial structure of soil landscape variability abstract the spatial structure of soil variability at the landscape scale was examined on adjacent geomorphic surfaces dating from 80 to 200 ka in eastern north carolina the purpose was to determine whether there is evidence at broader scales distances of 102 104 m for the divergent evolution observed in the field at very detailed scales distances of 100 102 m the state probability function spf which measures spatial dependence for categorical environmental data along a transect was applied to soil series mapped at a 1 24 000 scale the older talbot terrace and younger pamlico terrace surfaces showed distinctly different patterns of spatial variability the range of spatial dependence was shorter on the older surface about 200 vs 300 m and the spf was higher at any given distance indicating more variability the spf for the pamlico surface also indicates a periodicity related to fluvial dissection of the landscape which is not readily detectable on the talbot transect despite its greater degree of dissection the results confirm earlier field studies which suggest that pedogenesis is marked by divergence whereby differences in initial conditions or local perturbations persist and increase to produce a more variable soil cover

genesis of a texturally banded soil in southland new zealand abstract lamellae enriched with clay have been identified in profiles of the otama series during the course of field mapping in southland new zealand similar soils have been reported in a variety of landscapes from other parts of the world but explanations of their genesis differ considerably and do not fully account for the properties of the otama series macro and micromorphological analysis of this soil indicates a complex history in which the lamellae have formed by clay migration possibly under a seasonal freeze thaw environment as aeolian sediment was accumulating during the last glacial a cumulative mechanism of this kind may account for similar features in other aeolian landscapes limited bioturbation of lamellae occurred during the accumulation phase since establishment of a stable land surface during the holocene weathering gleying clay illuviation and bioturbation processes have been dominant with morphological features of present a and b horizons being superimposed on the uppermost lamellae and interlamellae

slope gradient and aspect effects on soils developed from sandstone in pennsylvania abstract this study was initiated to determine the basic characteristics and genesis of soils on gentle to very steep slopes on two contrasting slope aspects two transects a southwest sw and a northwest nw transect were laid out on a sandstone ridge across the summit and steepest convex shoulder positions the thickness of the o a and e horizons was not related to slope gradient across soils on all slope gradients and aspects this indicates that the present rate of soil formation is greater than erosion the influence of erosion on steep slopes could be off set by lateral movement of through flow water above the b horizon or the process of tree throw masks slope gradient effects solum depth b horizon thickness clay fe and al indexes decreased with increasing slope for both the nw and sw aspects organic carbon index decreased with increasing slope for the sw aspect decreases in effective precipitation over relatively larger surface areas at steep versus lower slope gradients a longer influence of periglacial erosion following the wisconsinan glacial advance and present slow but significant soil creep could cause these differences in soil development across the slope solum depth b horizon thickness clay fe and al indexes showed a smaller decrease across the nw compared to the sw slope organic carbon did not decrease across the nw slope the e horizon was also slightly thicker on the nw compared to the sw slope these aspect differences were probably caused by less evaporation on shaded nw compared to sunny sw slopes which produce generally higher moisture levels and more effective eluviation and illuviation on the nw slope

geogenesis pedogenesis and multiple causality in the formation of texture contrast soils abstract coarse over fine vertical texture contrasts vtc are common in soils and weathering profiles in a variety of environmental settings including many where inheritance or surficial processes alone cannot account for them a multiple causality model is presented here which shows that texture contrasts can form in response to a combination of ubiquitous phenomena there are six key elements downward translocation by water erosional winnowing soil mixing by bioturbation the tendency for surface clay additions to be mobilized while subsurface clays are more likely to remain in place and biological facilitation of moisture flux no element alone is sufficient to create a vtc but not all are necessary in any given regolith the model is illustrated by application to case studies in the ouachita mountains arkansas ridgetops in eastern kentucky the lower coastal plain of north carolina and the upper coastal plain of east texas the implications for interpretation of soils paleosols and weathering profiles is that the presence of a textural contrast by itself does not connote any particular set of geogenic or pedogenic processs or controls texture contrasts may be geogenic pedogenic or both given the widespread occurrence of the mechanisms of the multiple causality model vertical texture contrasts are inevitable

soil redistribution and pedologic transformations in coastal plain croplands in agricultural basins of the southeastern coastal plain there are typically large disparities between upland soil erosion and sediment delivered to streams this suggests that colluvial storage and redistribution of eroded soil within croplands is occurring and or that processes other than fluvial erosion are at work this study used soil morphology and stratigraphy as an indicator of erosion and deposition processes in a watershed at littlefield north carolina soil stratigraphy and morphology reflect the ways in which mass fluxes associated with cultivation transform the local soils fluvial aeolian and tillage processes were all found to be active in the redistribution of soil the soil transformations are of five general types first erosion and compaction in the cultivated area as a whole result in the thinning of arenic and grossarenic paleudults and paleaquults to form arenic typic and aquic paleudults and paleaquults second redistribution of surficial material within the fields results in transitions between arenic and typic or aquic subgroups as loamy sand a and e horizons are truncated or accreted third aeolian deposition at forested field boundaries leads to the formation of compound soils with podzolized features fourth sandy rill fan deposits at slope bases create cumulic soils distinct from the loamy sands of the source area or the darker finer terrace soils buried by the fan deposits finally tillage and fluvial deposition in upland depressions results in the gradual burial of rains poorly drained typic paleaquults soils results confirm the importance of upland sediment storage and redistribution and the role of tillage and aeolian processes as well as fluvial processes in the region copyright 1999 john wiley sons ltd

morphologic evidence of lamellae forming directly from thin clayey bedding planes in a dune an excavation in a sand dune in southern michigan revealed numerous thin 3m m clay enriched strata between otherwise weakly stratified clean fine sand deposits the parallelism of both the sandy and clayey strata suggest that they have direct geologic origins having been deposited during formation of the dune although the clay enriched strata and the intervening sandy layers are both within the sand textural class the former contained between 3 0 and 5 4 clay and the latter 1 8 clay in areas of preferred leaching such as below vertical root traces the clayey strata thin out and become absent or abend downwardb become wavy and contorted and take on the appearance of typical pedogenic lamellae these observations support a theory of lamellae genesis that is both pedogenic and geogenic thin sedimentary strata may be pedogeni cally atransformedb into features that would normally be described as entirely pedogenic lamellae thus many thin lamellae in pleistocene aged soils may simply be deformed and pedogenically altered sedimentary strata this conclusion has implications for the nature and cyclicity of clay deposition in environments where thin lamellae are common in sandy soils q 2001 elsevier science b v all rights reserved

truncation and accretion of soil profiles on coastal plain croplands implications for sediment redistribution soil stratigraphy and morphology in a small agricultural watershed on the coastal plain at clayroot north carolina indicate long term decadal scale patterns of the redistribution of sediment the most dramatic truncation of the soil profile occurs on convex upper slopes and suggests tillage and aeolian erosion as the major processes of soil loss thicker soils immediately downslope from convexities are consistent with redistribution by tillage but significant aeolian soil loss also occurs from some fields thinner apparently truncated soils were also associated with relatively steeper lower slope areas where contemporary rilling was observed the presence of thicker cumulic soils at toeslopes where small fans are observed at rill termini and about a half meter of alluvium in drainage ditches indicates that water erosion is also quite prominent distinctive soil stratigraphy is found in areas of aeolian deposition where podzolization in sandy surface deposits has created compound soil profiles on convex slopes tillage and wind erosion result in net soil loss with the former dominating on wetter soils and when plowing occurs and aeolian processes dominating on drier hilltops and when no till or minimum tillage practices are followed soils are thicker immediately downslope from convexities with thinner soils and rill erosion on lower slopes thickened soils and colluvial deposition in the form of thin fan deposits occur at toeslopes and in depressions the borders of fields often have thicker soils because of aeolian deposition water wind and tillage processes are all significant in soil redistribution at the clayroot site with relative importance in space and time controlled by topography soil properties seasonal moisture and vegetative cover and tillage practices

variability of soil physical quality and erodibility in a water eroded cropland abstract physical degradation of the soil increases its susceptibility to erosion by water action however relatively few studies have evaluated the opposite i e the impact of water erosion on soil erodibility this study was conducted in a corn field in ohio some sites within the field have experienced water induced soil erosion following heavy rainstorms physical characteristics of the soil were compared between eroded er and un eroded sites un compared with er the soil in un had lower penetration resistance 4 87 vs 4 53 mpa bulk density 1 45 vs 1 33 mg m 3 and sand content 17 4 vs 14 2 and higher shear strength 80 1 vs 125 3 kpa hydraulic conductivity 3 0 vs 3 4 cm h 1 intrinsic permeability 31 9 vs 36 4 10 10 cm 2 and contents of soil organic carbon 36 1 vs 32 1 g kg 1 total nitrogen 3 3 vs 3 1 g kg 1 clay 25 2 vs 24 2 silt 60 5 vs 58 4 and very fine sand 3 4 vs 1 1 also munsell s variables differed between er and un 1 24 vs 0 54 for hue 4 59 vs 4 35 for value and 1 99 vs 1 79 for chroma respectively the erodibility factor k was lower in un than in er 0 00327 vs 0 00354 mg ha h ha 1 mj 1 mm 1 respectively hence it is suggested the er sites within the corn field agroecosystem are more susceptible to accelerated erosion as compared with un sites

lateral flow in loamy to sandy kandiudults of the upper coastal plain of georgia usa abstract interest in site specific agronomic management in intensively cropped regions necessitates characterization of subsurface water movement for efficient water management irrigation timing and control of off site agrichemical movement soils formed in fluvial sediments in portions of the upper coastal plain of georgia usa are extensively used for peanut cotton and corn production certain proximate soils in this region possess contrasting subsoil properties and it was hypothesized that these differences would have major effects on water redistribution across the landscape this could be important in irrigation management where soils possessing increased impedance to vertical flow could require decreased irrigation as opposed to soils without vertical flow restrictions at a site near plains ga usa hydraulic properties of soils with differences in overlying sand thickness and contrasting argillic horizon textures sandy vs loamy were evaluated the soils were predominantly in loamy and sandy families of typic arenic and grossarenic kandiudults laboratory measurements field monitoring of matric potentials under simulated and natural rainfall and modeling vs2dt were utilized to evaluate soil hydraulic properties reduction in vertical k s occurred in horizons containing higher clay argillic horizon changes in tension and build ups in hydraulic gradients associated with infiltration and redistribution events existed above and within horizons with low k s evidence suggested there was less groundwater recharge occurring in the loamy than in the sandy pedons suggesting more pronounced lateral flow occurred in the loamier soils model simulations of water movement across a slightly sloping 1 simulated landscape indicated lateral gradients of flow existed within the solum of these soils analyses of tracer br movement suggested a very slight lateral redistribution occurred within a relatively short monitoring period within the sandy pedon s bt1 horizon and the bt2 and bt3 horizons of the loamy pedon evidence suggested both loamy and sandy argillic horizons slightly but not overwhelmingly induced lateral flow on these landscapes

comparing the ability of soil taxonomy 2014 and wrb 2015 to distinguish lithologic discontinuity and an abrupt textural change in major soils of iran abstract a considerable increase in clay content within a very short distance and significant change of particle size distribution or mineralogy are diagnostic soil properties defined as abrupt textural change and lithologic discontinuity in the most soil classification systems i e soil taxonomy st and world reference base for soil resources wrb this study investigates the ability of the latest versions of st 2014 and wrb 2015 to classify soils that have an abrupt textural change and lithologic discontinuity six study sites were selected from different regions north middle north central south southeast and west of iran one representative pedon was selected described and sampled in each study site the physicochemical properties of the different genetic horizons of each pedon were determined and the soils were classified according to the st 2014 and wrb 2015 systems in the st system the abrupt textural change characteristic was only used for some of the great groups or subgroups furthermore the abruptic qualifier was not considered for all of the reference soil groups rsgs in the wrb system although the presence of lithologic discontinuity at taxon name was totally neglected by the st system the wrb system showed this property with the raptic qualifier this seems to be a limitation for both of the soil classification systems thus the management of soils with abrupt textural change and lithologic discontinuity still faces an important challenge to overcome this problem and to harmonize both the classification systems defining new great groups such as palegypsids and new subgroups including lithic calcixerepts calcic palexerolls abruptic argigypsids calcic argigypsids calcic paleustalfs and the raptic subgroup for all taxa in the st system is highly recommended the addition of abruptic qualifier for the rsgs such as chernozems calcisols and gypsisols seems necessary in the wrb system

origins and implications of soil layering abstract layering is common in soils due to a variety of pedologic and geologic processes and has important consequences for the interpretation of soils and landscapes layering can derive from original sedimentary layering depositional upbuilding episodic surface erosion deposition and stability soil production by weathering vertical or lateral translocation bioturbation and various combinations of these complex and polygenetic models incorporate both geogenic and pedogenic processes and allow for physical and biological processes as well as both vertical and horizontal movements we review these conceptual frameworks and synthesize them into a vertical contrast model vcm for interpreting layered surficial materials the vcm incorporates a variety of geologic and pedologic processes which may create destroy enhance or obscure vertical contrasts the model is illustrated via application to sites in the ouachita mountains usa and northwest saxonian lowlands germany the examples illustrate the importance of a comprehensive pedogeomorphic interpretation of layering since neither standard stratigraphic or top down pedogenetic principles necessarily apply the examples also show that the same process can sometimes contemporaneously both create and destroy vertical contrasts

spatial variability of soil hydraulic conductivity along a tropical rainforest catena abstract we investigate the spatial variability of saturated hydraulic conductivity ksat along a tropical rainforest catena which consists of a typic kandiudult latossolo vermelho distrofico argissolico and plinthic hapludox latossolo amarelo distrofico tipico the former soil type extends from midslope to interfluve and has a high clay content throughout the profile whereas the latter soil type extends from the midslope to valley bottom and only has a high clay content at depths 90 cm we measured ksat along a transect at depths of 20 30 50 and 90 cm with a compact constant head permeameter ksat is not significantly different 0 10 between these soil types at any depth except for 90 cm ordinary and robust linear regression models with distance from the interfluve as in the independent variable showed no significant change in ksat as a function of topography loess regression showed some dependency of ksat on topography only at the 90 cm depth semivariograms showed no apparent spatial structure in ksat at distances 25 m for all depths we conclude that the strong topography dependence of soil types along this catena and hence primary soil attributes is not reflected in a similar dependence of ksat and tentatively attribute this lack of dependence to the overriding influence of bioturbation controlled macroporosity we outline a framework for detecting possible ksat topography relationships based on the distinction between bioturbation controlled nonstructural macroporosity and mineralogy controlled structural macroporosity

luvisols or cambisols micromorphological study of soil truncation in young morainic landscapes case study brodnica and chelmno lake districts north poland abstract eight soil profiles in brodnica lake district and chelmno lake district were described and sampled the profiles were divided into four pairs study areas dissimilar in lithology relief or land use each pair of profile contained soil located on the crest or upper slope exposed to erosion and back slope slightly exposed to erosion positions the relief of this area is inherited from the last vistulian glaciation and represents mostly flat and hummocky moraine plateau landscapes all investigated pedons have a b horizon five profiles have vertical contrasting texture and contain a significantly developed eluvial zone a and e horizons above b horizon in three cases pedons have a b c horizon sequence to date numerous studies have shown that the soils with a b c profiles developed on moraine tills should be treated as cambisols on existing soil agricultural maps these soils are also marked as cambisols the b horizons are enriched in the clay fraction and contain low amount of carbonates in comparison with the parent material all these criteria can be used to distinguish a cambic horizon but analysis of thin sections revealed the presence of significant amounts of clay and silt illuvial features the illuvial pedofeatures resulted in these horizons being classified as argic horizons bt these soils cannot be classified as cambisols which are characterized by absence of appreciable amounts of illuvial silt and clay instead the a b c profile forms represent truncated luvisols in which the material from eluvial horizons was entirely removed the soils described in this study occur in areas where soil erosion is common the upper part of slopes and crests in arable areas the illuvial origin of b horizons in truncated pedons a b c was also confirmed by the presence of eluvial horizons in nearby soils on the back slope position slightly or non exposed to erosion the results showed that accelerated erosion had a significant role in development of soil cover in agriculture moraine landscapes of brodnica and chelmno lake districts the micromorphological analysis confirmed that the loamy soils with the a b c profile developed on ground moraine tills should be classified as truncated eroded luvisols the b horizons of these soils have significant accumulation of clay and silt features the illuvial microforms are the relic feature of eluviation illuviation lessivage process the material from the eluvial horizons of luvisols was entirely removed this study is important to understand the influence of soil erosion processes on soil cover development in young glacial regions further investigations concerning formation and characteristic of a b c soils and appropriate classification of described pedons are very important for understanding the impact of accelerated erosion in young glacial landscapes

uranium series dating of fossil corals from marine sediments of southeastern united states atlantic coastal plain extensive low lying marine deposits border the southeastern united states atlantic coastal plain some units are fossiliferous and contain corals as isolated fragments in sediments of a detrital character these corals are subject to alteration processes such that suites of related samples must be examined to determine the suitability of these coral samples for reliable uranium series dating with the exception of those from one location most samples appear to have remained closed systems with respect to the isotopes of uranium and thorium throughout their geologic history extraneous 230th has been detected in some of the corals due to incorporation of some detrital materials into their skeletons for these samples different methods are applied to correct for the initial 230th contamination continued sampling and analyses have resulted in 55 individual uranium thorium determinations the average 230th ages of samples from the norfolk formation and from later and earlier deposited sediments of the wando formation are 71 000 87 000 and 129 000 yr and they appear to correlate with oxygen isotope substages 5a 5c and 5e respectively the average 230th age of samples from beds of the rappahannock river ponzer and ten mile hill localities is 212 000 yr and they correlate with oxygen isotope stage 7 the sediment of the canepatch formation is 460 000 yr old and it is tentatively correlated with oxygen isotope stage 11 there is general agreement between uranium series and uranium trend dates and between the quantitative trends of the amino acid data and uranium series dates the amino acid values however ure unacceptably high in at least two groups of samples those from localities near charleston south carolina and from central virginia

alluvial soil chronosequence in the inner coastal plain central virginia abstract a chronological sequence of soils formed on a series of alluvial depositional surfaces ranging in age from late middle miocene to late pleistocene was characterized to clarify soil geomorphic relations and provide a basis for allostratigraphic subdivision of the inner coastal plain on quaternary river terraces ultic hapludalfs containing abundant weatherable mineral species and clast types are estimated to have formed in 60 000 120 000 yr whereas typic hapludults greatly depleted in weatherable minerals and showing strong weathering of clast types are estimated to be 700 000 1 600 000 yr old typic paleudults with incipient plinthite duripan and ferricrete development characterize interfluves that have been little eroded since early pliocene time 3 4 5 3 myr ago typic plinthic paleudults with intense weathering of siliceous clasts and moderate to strong duripan and ferricrete development are found on surfaces that formed near the beginning of late miocene time 10 8 13 0 myr ago chemical weathering in the chronosequence may be classified into three progressive stages 1 decomposition of unstable sand and silt sized minerals into a mixed stable unstable clay mineral suite stable fe al si bulk chemical composition 107 yr not all soil properties show unidirectional development nor is a steady state of pedon development observed even after approximately 107 yr of chemical weathering soil development in the chronosequence is episodic the transition from one phase to the next is marked by a change in rate and sometimes a reversal in the direction of development of one or more soil properties

soil genesis optical dating and geoarchaeological evaluation of two upland alfisol pedons within the tertiary gulf coastal plain abstract much of the gulf coastal plain is mantled by sandy a and e soil horizons overlying finer grained bt horizons researchers have applied optical stimulated luminescence osl dating to a variety of depositional settings such as hillslopes and terraces in an attempt to understand depositional versus pedogenic origins of the sandy horizons and archaeological burial processes these investigations have documented a range of integrity conditions from pristine to highly bioturbated however little work has been conducted in upland summits thus we integrated field morphological descriptions constituent mass balance reconstruction and optical dating to reconstruct the timing and pedogenic pathways of two summit alfisols on the tertiary gulf coastal plain in texas investigations reveal that the sandy a and e horizons and the bt horizons in each pedon are genetically related with textural contrasts resulting from pedogenic processes optical dating revealed highly complex age structures strongly influenced by bioturbation weathering and the presence of coarse clay plus total silt particle sizes pedogenic mixing is extensive in the a and e horizons which effect apparent osl ages

comparison of amino acid racemization geochronometry with lithostratigraphy biostratigraphy uranium series coral dating and magnetostratigraphy in the atlantic coastal plain of the southeastern united states the results of an integrated study comprising litho and biostratigraphic investigations uranium series coral dating amino acid racemization in molluscs and paleomagnetic measurements are compared to ascertain relative and absolute ages of pleistocene deposits of the atlantic coastal plain in north and south carolina four depositional events are inferred for south carolina and two for north carolina by all methods the data suggest that there are four pleistocene units containing corals that have been dated at about 100 000 yr 200 000 yr 450 000 yr and over 1 000 000 yr some conflicts exist between the different methods regarding the correlation of the younger of these depositional events between charleston and myrtle beach lack of good uranium series dates for the younger material at myrtle beach makes the correlation with the deposits at charleston more difficult

nest structure of ant lasius neoniger emery and its implications to soil modification abstract the ant lasius neoniger emery is one of the most abundant ant species found in the temperate regions of north america and has been studied primarily from an entomological standpoint this study was conducted to characterize its nest structure and implications to soil modification to study the structure development and micromorphological characteristics of the ant nests we constructed three dimensional models of the nests from excavated nest castings made with dental gypsum and ant farms with plexiglas and made thin sections 30 m thick from undisturbed field soil samples that contained the nests we assessed the effect of the ant on soil chemical properties by comparing the composition of ant crater rim and nest materials with that of associated bulk soil the ant nests consisted of underground branched networks of galleries and chambers concentrated in the upper 0 3 m of the soil with a few vertical galleries penetrating to about 0 7 m the galleries tended to be circular tubes channels 1 5 to 5 0 mm in diameter whereas the chambers connected by the galleries bulged to diameters of 10 to 20 mm and were 30 to 50 mm in length the volume of the nests ranged from 20 to 250 cm 3 walls of the nests 1 m thick were more consolidated and contained larger amounts of fine sand silt and colloidal material than adjoining bulk soil the primary effect of the ants was mixing of the upper 0 7 m of soil estimated soil turnover time ranges for upper 0 3 m soil from approximately 1000 years for the grass border areas of a corn field to 2800 years inside the field for soils between 0 3 and 0 7 m depths estimated soil turnover time ranges from approximately 9000 years for the grass border areas to 24 000 years inside the corn field selective mining by ants of fine particles which concentrate in the upper tier of the soil may also counter balance processes such as clay translocation and nutrient leaching that tend to degrade physical and chemical attributes of sandy soil surfaces forming in humid environment

development of texture contrast soils by a combination of bioturbation and translocation abstract soils and weathering profiles in a wide variety of parent materials and environmental settings exhibit coarse over fine vertical textural contrasts where these cannot be attributed to inherited texture contrasts or erosion deposition the most common explanations are based on translocation eluviation illuviation which removes clays from surface layers and deposits them in the subsoil or bioturbation where preferentially fine material is delivered to the surface by organisms from whence erosional winnowing creates a coarse surface layer in some soils of the lower coastal plain of north carolina u s a neither explanation is sufficient to explain the observed texture contrasts a heuristic model based on a combination of translocation of fine material from surface to subsoil and bioturbation driven delivery and recycling of material to the surface can explain the observed vertical textural contrasts the key elements in the model are coastal plain sediments which include some fine material eluviation illuviation by percolating water delivery of additional fine and mixed grain size material to surface by bioturbation making it available for translocation concentration of fine material originally scattered throughout the parent material in a b horizon and maintenance of vertical moisture fluxes by bioturbation the model is supported by morphological evidence of the key mechanisms argillic horizons that are finer than both the surface layers and underlying parent material evidence that argillic horizon formation is not limited by the rate of clay synthesis and the absence of texture contrasts in nearby soils formed from dune sands which lack fines

pleistocene holocene cover beds on granite regolith as parent material for podzols an example from the sudeten mountains abstract pleistocene periglacial cover beds have been considered to be the proper parent material of soils in the medium mountains of the central europe and in other areas influenced by the periglacial conditions the concept highlights an importance of solifluction and cryoturbation phenomena and an addition of aeolian silt loess in the formation of cover beds significant loess admixture may however hinder podzolization process the objective of the present study was to recognize the stratification of slope materials in the upper zone 1000 1200 m asl of the sudeten mts sw poland and its relation to the morphology and properties of podzols mineralogical and submicromorphological analyzes confirmed autochthonous origin of the parent materials and excluded loess admixture macro and micro observations proved periglacial formation of deeper beds while the pollen analysis confirmed the holocene age of an uppermost sand layer finally four partial mineral sequences were distinguished in soil profiles 1 an underlying granite regolith not always present within the standard soil pit 2 a basal periglacial layer formed by solifluction 3 a cryoturbated transitional zone instead of typical intermediate periglacial layer 4 an uppermost sandy or a sandy silty layer instead of the upper periglacial layer modification of periglacial cover bed series by replacing of the silty upper periglacial layer with sandy holocene cover allowed podzol formation under favorable climate conditions the same palynological and micromorphological observations confirmed polygenetic nature of podzols the present day bh horizon is in fact a humus layer of a late pleistocene early holocene brown earth buried under a sandy cover an albic horizon thickness and its lower boundary are therefore related to the lithological discontinuity in the cover bed series

the state of au and as in pyrite studied by x ray absorption spectroscopy of natural minerals and synthetic phases abstract in many hydrothermal deposits arsenian pyrite contains economic concentrations of au in an invisible form which is structurally bound in pyrite or has grain size