using 137cs and 210pbex measurements to estimate soil redistribution rates on semi arid grassland in mongolia abstract in this study two small experimental catchments were selected in semi arid grassland in mongolia the kherlen bayan ulaan kbu catchment has been subjected to intensive grazing as a wintering shelter for domestic livestock animals and the number of livestock animals in the baganuur bgn catchment has been increasing over the last few decades the rates and patterns of soil erosion within the catchments were estimated based on cesium 137 137 cs and lead 210 210 pb ex inventories in bulk soil core samples the medium term 40 years soil erosion rates based on the 137 cs measurements indicated that annual soil loss from the kbu catchment was approximately three times greater than that from the bgn catchment the 137 cs derived rates and patterns of soil erosion indicated that soil in the kbu catchment was susceptible to surface erosion with facilitated transport of eroded sediment to the catchment outlet the 210 pb ex derived soil erosion rates were generally greater than those derived from 137 cs in both catchments if we assume that the soil erosion rate has been increasing with increasing domestic livestock numbers the most plausible explanation is that the 210 pb ex derived estimates represent recent increases in soil erosion furthermore the 210 pb ex 137 cs inventory ratio showed a tendency to increase with downslope distance on the eroded hillslope in the bgn catchment assuming that the increase in inventory ratio is a result of constant fallout input of 210 pb ex on the eroded sediment during its transportation along the hillslope the 210 pb ex inventory may not be suitable to estimate soil erosion rates at sites where downslope movement of sediment is slow further discussion regarding interpretation of 210 pb ex derived soil loss is required and the applicability of the 210 pb ex technique on semi arid hillslopes remains to be determined

the 137cs technique applied to steep mediterranean slopes part i the effects of lithology slope morphology and land use concentrations in the soil of anthropogenic and natural radionuclides have been investigated in order to assess the applicability of the cs 137 technique in an area of typical mediterranean steep slopes this technique can be used to estimate net soil redistribution rates but its potential in areas with shallow and stony soils on hard rock lithology have not been evaluated so far in this research the validity of using this technique in stony shallow soils at very steep slopes is discussed together with the relations between radionuclide concentrations and other soil properties lithology slope morphology and land use in a mediterranean environment both natural potassium 40 4 k uranium 238 u 238 thorium 232 th 212 and anthropogenic caesium 137 cs 137 radionuclides have been determined in samples taken along slope transects on uncultivated serpentinite soils and cultivated gneiss soils in addition to the radionuclide concentrations parameters such as slope position slope angle aspect soil depth surface stone cover moss litter vegetation cover soil crust stone content and bulk density have been quantified all the natural radionuclides k 40 u 238 th 232 show significantly higher concentrations in the gneiss than in the serpentinite soils opposed to the cs 137 concentration which is found significantly higher in the serpentinite soils probably because of the difference in clay mineralogy the exponential decreasing depth distribution of cs 137 and its homogeneous spatial distribution emphasise the applicability of the cs 137 technique in this ecosystem lithology determines the concentration of natural and anthropogenic radionuclides land use determines the relations between cs 137 concentration inventory and some soil characteristics higher cs 137 concentration and inventory are associated with higher percentages of vegetation cover higher percentage of stones in the soil and higher values of soil bulk density in cultivated gneiss soils slope morphology and land use influence the soil redistribution at slope scale the gneiss slopes show a zonation of four to five areas of differential erosion accumulation processes corresponding with more regular slopes and soil redistribution due to water erosion and to tillage translocation and erosion the serpentinites as an example of a more unstable slope type show more erosion areas with less accumulation downslope and soil redistribution due to water erosion c 2003 elsevier b v all rights reserved

the measurement and modelling of rill erosion at angle of repose slopes in mine spoil the process of rill erosion causes significant amounts of sediment to be moved in both undisturbed and disturbed environments and can be a significant issue for agriculture as well as mining lands rills also often develop very quickly from a single rainfall event to a season and can develop into gullies if sufficient runoff is available to continue their development this study examines the ability of a terrestrial laser scanner to quantify rills that have developed on fresh and homogeneous mine spoil on an angle of repose slope it also examines the ability of the siberia erosion model to simulate the rill s spatial and temporal behaviour while there has been considerable work done examining rill erosion on rehabilitated mine sites and agricultural fields little work has been done to examine rill development at angle of repose sites results show that while the overall hillslope morphology was captured by the laser scanner with the morphology of the rills being broadly captured the characteristics of the rills were not well defined the digital elevation model created by the laser scanner failed to capture the rill thalwegs and tops of the banks therefore delineating a series of ill defined longitudinal downslope depressions these results demonstrate that an even greater density of points is needed to capture sufficient rill morphology nevertheless siberia simulations of the hillslope demonstrated that the model was able to capture rill behaviour in both space and time when correct model parameters were used this result provides confidence in the siberia model and its parameterization the results demonstrate the sensitivity of the model to changes in parameters and the importance of the calibration process copyright 2007 john wiley sons ltd

youngest ambient inclusion trails from middle triassic phosphatized coprolites southwestern china new insights into an old intriguing phenomenon abstract copious microtubular structures are reported for the first time from the coprolites of early middle triassic guanling formation in luoping yunnan province southwestern china multiple salient characteristics of these microtubes including curved to coiled grooves with longitudinal striations angular turns cross cuttings and a terminal rounded pitting at one end of a groove support their strong affinities with ambient inclusion trails aits that are more commonly found in pre ediacaran sedimentary rocks these newly found microtubular structures are here interpreted to represent the youngest occurrence of aits in the geological record a review of all aits and similar microtubular structures reveals their common occurrences in ediacaran phosphorite and phanerozoic phosphatized fossil substrate similar to the aits found from the post ediacaran strata the aits from the luoping coprolites are also preserved in a phosphatized substrate we suggest that a microbial induced process might have contributed to the phosphogenesis of faeces and aits formation this process is interpreted to have involved the precipitation of phosphate minerals by microbial communities and the movement of pyrite through and within phosphatized substrate gel driven by fluid pressure this new interpretive model differs from the existing scenario invoked to explain the formation mechanism of pre ediacaran aits in which pyrite propulsion is thought to be more likely driven by metamorphism induced fluid pressure we thus hypothesize that the transformation in aits formative substrate from chert to phosphate as well as their formation mechanism might have been triggered by a significant change in ocean biogeochemistry linked to a phosphogenic event in the neoproterozoic

strandflat development and quaternary shorelines on tiree and coll scottish hebrides the islands of tiree and coll in the scottish inner hebrides are dominated by staircases of glaciated rock platform surfaces in lewisian gneiss that are interpreted here as areas of strandflat the rock platform surfaces exhibit differential glacio isostatic uplift from east to west and are considered to indicate at least four separate periods of strandflat formation during prolonged intervals of quaternary cold climate it is suggested that many of the well known areas of high rock platform located farther east in the scottish inner hebrides represent eroded remnants of the strandflat surfaces described here the existence of the tiree and coll strandflat surfaces in conjunction with their formation during periods of quaternary glaciation implies that they were produced during periods when mainland scotland was ice covered yet when the western margin of the ice sheet was normally located east of these islands a prominent late glacial raised shoreline also occurs on both islands and declines in altitude to the west from 22 m in northeastern coll to 9 m in western tiree it is believed that this shoreline whose regional gradient is 0 39 m km 1 may represent part of the main wester ross shoreline that was formed in the northwest highlands of scotland during a period of glacial advance that interrupted the decay of the last late devensian ice sheet the general similarity in altitude between the late glacial shoreline features and rock platform surfaces implies that during each period of quaternary strandflat formation relative sea level returned to the same approximate position this would appear to indicate that the glacio isostatic and glacio eustatic components affecting the positions of relative sea level in scotland have remained in approximate equilibrium throughout the duration of the quaternary

now a bone then calcite abstract critical transformation and degradation of skeletal tissues most frequently affect their organic components while the mineral component of bones and fossils comprises one of the most stable mineral groups on earth the apatites the case we present here relates to fossil bones from palaeolake shores whose shapes are preserved within the sediment itself but which disintegrate into a chalky disaggregated substance at the slightest touch or breath the rarity of bone apatite transformation into calcite is due to the extreme insolubility and stability of bone mineral which is highly tolerant of ionic substitutions and inclusions without changing its basic mineral nature and composition observation of this chalky substance under high magnifications reveals a delicate structure of microcrystals these crystals enclose microtunnels and grooves identical in shape and size to the characteristic bone bioerosion caused by aquatic microorganisms this microtunnelling preservation allows us to confirm that disaggregate calcite crystals replaced areas where once there had been bone furthermore the bone chalky material transformation had to occur when microorganisms were still in the interior of these tunnels otherwise the delicate empty microtunnels observed today would have collapsed two calcareous palaeo lakeshore sites show identical phenomenon detailed taphonomic environmental and chemical studies indicate that the transformation process was initiated by microorganisms arising from a combination of their metabolism and the alkaline environment they inhabited that caused a local and sudden increase in local acidity this chalky material is referred to as biogenic in contrast to environmental calcite deposits geodes and calcite infilling bone fissures that formed in the lake conditions the calcium carbonate phase of both biological and environmental origin in these two palaeolakes is aragonite which forms under restricted situations of aridity and warming and may provide a precise indication of environmental conditions when these sites formed similar situations may occur today in arid areas

gis based simulation of erosion and deposition patterns in an agricultural landscape a comparison of model results with soil map information abstract this paper presents a relatively simple two dimensional hillslope erosion deposition model the model differs from most geomorphological models in that it does not assume that erosion by surface wash is always transport limited as a first test the model is applied to an agricultural catchment in central belgium here patterns of past erosion and deposition can be deduced from information contained in the belgian soil map so that a qualitative validation of the model results is possible the results indicate that a simple model formulation allows to reproduce the basic pattern of erosion and deposition as it is observed in the landscape this confirms the major influence of topography on erosion and deposition patterns in such landscapes and indicates that in some cases a simple model formulation may well be sufficient to allow adequate modelling of landscape evolution

sand drift and soil formation along an exposed north atlantic coastline 14 000 years of diverse geomorphological climatic and human impacts this paper sets out the history of aeolian deposition and soil formation over the last 14 15 000 calendar years along the exposed and gale prone atlantic coastlines of the southern isles of the outer hebrides of scotland detailed palaeoenvironmental interpretation and chronological control have been provided by field mapping soil micromorphological analyses and radiocarbon and optically stimulated luminescence osl dating programmes two dominant types of aeolian sands are described in this region quartzose sands are shown to originate mainly as periglacial wind blown sands derived from glacial and periglacial deposits of late devensian age which were formerly exposed on the present continental shelf this aeolian deposition did however continue into the early holocene with re working perhaps by slope wash taking place as recently as the 4th millenniumbp quartzose sands mantle valley floors and hillslopes by the end of the devensian and early holocene a variety of soil types with extensive horizonation had developed upon them including podzolic brown earths peaty gleys and peat soils radiocarbon and osl dating demonstrate that the carbonate sands of the machair sand sheets which characterize the present atlantic shorelines began to accumulate very early for a european shoreline from approximately 8700 calendar years ago on benbecula and north uist whereas further south deposition began later osl dating suggests that non sequences and diastems are common in greater part these machair sand sheets are best interpreted as a composite of separate slivers of sand reflecting small scale and local episodes of sand drift rather than distinct layers of region wide distribution which might reflect past major storms or significant palaeoclimatic fluctuations the new evidence presented here provides little support for the following explanatory geomorphic or stratigraphic models which have previously sought to explain the development of these coastal machair landscapes continuous development layer cake or step wise prograding coastal barrier qualified support is given for the explanations that emphasize i the long term spasmodic input and re cycling of sands and ii that the present smoothed landscapes and distinctive machair grassland vegetation are essentially recent in age and reflect the interactions of natural and human processes in a stormy environment characterized by re working widespread layers of thick organic materials within the carbonate sands in the study area which have previously been regarded as dune palaeosols dating to the bronze age and iron age are suggested by soil micromorphological analysis to be in significant part anthropogenic in origin they are organically enriched layers or midden soils the consequence of human activities notably the disposal of organic wastes and other forms of soil modification during times of significant settlement in these coastal sands these periods of relatively intense human activity are therefore shown to be associated at least locally with periods of soil formation and stability not universal instability and dune drift along these shorelines in general these extensive layers of midden soil do not necessarily imply periods of decreased storminess relatively widespread soil formation in these coastal dunes did however take place in the period between 400 and 100 years ago essentially within the period of increased storminess associated with the little ice age it is suggested that at some point s within the following periods of time broadly defined in calendar yearsbp notable sand drift affecting the quartzose sands the carbonate sands or both took place within the study area 13 700 13 000 11 000 10 500 9000 8300 7500 7000 6900 6400 5800 4200 one of the most notable episodes of drift in the outer hebrides as well as elsewhere on the coast of north west europe 3800 3300 1700 1300 600 200 with individual great storms being recorded in the 17th and 18th centuries and 100 present day limited drift associated with machair stratification

the 137cs technique applied to steep mediterranean slopes part ii landscape evolution and model calibration over the past years the caesium 137 cs 137 technique has been successfully applied in numerous environments all over the world this technique is using the worldwide distribution of the anthropogenic cs 137 radionuclide and its redistribution associated with soil particles as an effective estimation of net soil loss rates in contrast to numerous studies on deep often cultivated clay soils with gentle to intermediate slopes typical mediterranean shallow stony soils on steep slopes have received less attention in this paper the landscape evolution over the past 37 years has been evaluated using the cs 137 technique for two lithological different areas under contrasting land use in the alora case study area malaga spain in soils on gneiss and serpentinite bedrock several transects have been selected on steep slopes up to 35 with mean soil depths from 37 cm for gneiss to 24 em for serpentinite estimating net soil redistribution rates from radionuclide distributions depends on the calculation of the local area reference inventory and the used calibration technique several methods have been tested and final results were found to differ considerably after careful parameter selection the resulting net soil redistribution estimates for the different transects have been compared with simulations of a simple landscape evolution model resulting in different possible scenarios of erosional response total net soil loss for the study area range from 2 3 0 25 to 69 1 7 8 t ha 1 year 1 for serpentinite and gneiss slopes respectively differences in total slope sediment budgets as well as differences along the transeets reveal influences of landscape representation and land use in this case the impact of soil translocation by tillage and resulting erosion rates are far more important than possible parent material induced differences however comparing the two sampled areas not only net rates but spatial patterns as well reveal important differences in distribution over the landscape of net erosion and net sedimentation zones c 2003 elsevier b v all rights reserved

fractal features of soil particle size distribution in layered sediments behind two check dams implications for the loess plateau china abstract the layered sediment deposited behind a check dam can provide useful information about soil erosion processes in the dam controlled area this study aims to evaluate the possible fractal nature of layered sediments behind check dams assessing whether fractal dimension can serve as a feasible index for evaluating the impact of land use types on the area controlled by the check dam fractal dimension measurement was employed to analyze the features of soil particle size distribution psd for different layered sediments of the shipanmao and zhangshan check dams in the dalihe river basin of the loess plateau china results show that the predominant soil particle sizes of the sediment layers behind the shipanmao and zhangshan dams are silt clay cv for the coarse sand fraction is highest followed by the fine sand and the silt clay size fractions larger soil particle sizes coincide with larger cv values the fractal dimension d m of the psd ranges from 2 111 to 2 219 and 2 144 to 2 447 for shipanmao and zhangshan respectively the d m values tend to increase and decrease for the layered sediments from top to bottom with some turning points the turning points of d m are related to the trends of the soil psds in the adjacent sediment layers although d m has significant positive and negative correlations with the silt clay and the fine sand size fractions respectively no correlation with the coarse sand fraction was observed soil psd is a more dominant factor affecting d m than the time lag between soil erosion and sediment deposition overall d m decreased for shipanmao during the deposition period 1972 1979 the total increment of the c factor in the universal soil loss equation and the soil erosion amount per rainfall erosivity were applied to analyze land use changes between 1972 and 1979 for the dam controlled area of the shipanmao dam the total increment of c during 1972 1979 was 0 021 and the soil erosion amount per rainfall erosivity was smaller in 1972 than in 1979 indicating desertification in the dam controlled area in addition the land use types prevalent in 1979 were more prone to soil loss than those in 1972 d m is a useful parameter to assess land use types and soil degradation processes in dam controlled areas of the loess plateau

holocene relative sea level changes in harris outer hebrides scotland uk evidence for relative sea level changes during the middle and late holocene is examined from two locations on the atlantic coast of harris outer hebrides scotland using morphological mapping and survey stratigraphical grain size and diatom analysis and radiocarbon dating the earliest event identified is a marine flood which occurred after 7982 8348 cal a 7370 80 14c a bp when the sea crossed a threshold lying at 0 08 m ordnance datum newlyn od 2 17 m mean high water springs mhws before withdrawing this could have been due to a storm or to the holocene storegga slide tsunami by 6407 6122 cal a 5500 60 14c a bp relative sea levels had begun to fall from a sandflat surface with an indicated mhws level of between 0 08 and 1 96 m 2 01 to 4 05 m this fall reached between 0 30 and 2 35 m 2 39 to 4 44 m after 5841 5050 cal a 4760 130 14c a bp but was succeeded by a relative sea level rise which reached between 0 54 and 1 57 m 1 55 to 3 66 m by 5450 4861 cal a 4500 100 14c a bp this rise continued possibly with an interruption until a second sandflat surface was reached between 2 34 and 0 26 m 0 25 to 2 35 m between 2952 3375 cal a 3000 80 14c a and 1948 2325 cal a 2130 70 14c a bp before present levels were reached the regressive episode from the earliest sandflat is correlated with the abandonment of the main postglacial shoreline it is maintained that the fluctuations in relative sea level recorded can be correlated with similar events elsewhere on the periphery of the glacio isostatic centre and may therefore reflect secular changes in nearshore sea surface levels despite published evidence from trim lines of differential ice sheet loading across the area no evidence of variations in uplift between the locations concerned could be found copyright 2009 john wiley sons ltd

modeling the accumulation and dynamics of beaches on shore platforms a mathematical model was used to study the development and dynamics of beaches on shore platforms the model was based on assumptions that the gradient of the beachface at its seaward edge must be greater than platform gradient beach sediment tends to move landwards and beach occurrence and extent depends upon the amount of sediment available equilibrium beachface gradient was related to breaker height wave period and sediment grain size three grain sizes were used representing fine and coarse sand and pebble two deep water wave sets representing storm wave and west coast swell wave environments and two tidal ranges of 9 1 and 3 3 m runs were made using linear concave and convex platform profiles with gradients ranging between about 0 6 and 8 because platform and beachface gradients are normally quite similar shore platforms are unable to store much sediment for a linear platform with a lower gradient than the beachface sediment first accumulates at the cliff base and then depending on the sediment available extends increasingly seawards beach development first occurs on the gently sloping seaward portions of concave platforms and on the more landward portions of convex profiles the amount of available material partly determines the landward and seaward extent of these beaches respectively although it is also controlled by beachface and platform gradients beaches on shore platforms become thinner and more gently sloping during storms and they may disappear completely depending on such factors as sediment grain size platform gradient the amount of sediment that can be stored during calm conditions wave characteristics and the duration of the storm the response of beaches on rocky coasts to rising sea level will be different from those on sedimentary coasts and will depend in part on the morphology of the rocky foundation

a new taphonomic bioerosion in a miocene lakeshore environment abstract this study describes a new type of taphonomic alteration of fossil bone that occurred in a continental carbonate palaeolake environment at the reference spanish miocene site of cerro de la garita concud teruel scanning electron microscopy showed this type of alteration to be characterized by microtunnels that penetrate inward from the bone surface and by a branching meandering arrangement of microchannels on the bone surface these microtunnels had a highly electron dense inner wall seen as a characteristic rim in transverse section microspheres were seen inside the microtunnels both this electron dense layer and these microspheres were found to be composed of calcium phosphate these taphonomic modifications bear some similarities to but also differs from those caused by bacterial attack on bone and enamel in marine and terrestrial environments suggesting the present process to be a new type of bioerosion the microspheres inside the microtunnels were similar in size shape and composition to the fossilized bacteria covering fossils from fossil lagersttaten palaeolake sites such as libros teruel spain and messel germany under the transmission electron microscope these structures showed an apparent cell wall suggesting them to be fossilized coccoid bacteria

is barrier island morphology a function of tidal and wave regime abstract classification of barrier island morphology stems from the seminal work of m o hayes and others which linked island shape to tidal range and wave height and defined coastal energy regimes i e wave dominated mixed energy tide dominated if true this general relationship represents a process based framework to link modern and ancient systems and is key for determining paleomorphodynamic relationships here we present a new semi global database of barrier islands and spits n 702 shape parameters aspect circularity and roundness are used to quantify island boundary shape and assess potential correlation with coastal energy regime using global wave and tide models in adopting the original energy classification as originally put forth i e wave dominated wave influenced mixed tide influenced mixed tide dominated results show that wave dominated islands have statistically different mean shape values from those in the mixed energy fields but the two mixed energy designations are not distinct from each other furthermore each energy regime field contains a wide range of island shapes with no clear trends present linear regression modeling shows that tidal range and wave height account for

modelling water flow and sediment processes in a small gully system on the loess plateau in china abstract a single gully system was selected in a small agricultural watershed on the loess plateau of china with the objective of measuring and then simulating water and sediment transport and defining alternative land uses to reduce discharge and soil loss the gully had a total length of about 40 m and was about 30 m wide the watershed feeding the gully occupied about 1950 m 2 including the gully itself the gully bottom had a slope of about 32 40 whereas the gully walls were from 40 to over 60 soil water content and water and sediment discharge were measured automatically the physically based hydrological and soil erosion model lisem was used to calculate water and sediment discharge calibration has been carried out for one event by adjusting the saturated conductivity values validation was performed for two additional runoff events calibration results show reasonably comparable hydrographs between measured and calculated discharge lisem could be calibrated on the hydrograph quite satisfactorily using the saturated conductivity as a calibration factor also validation of lisem for two other runoff events showed reasonably good results the calibration on total soil loss also shows good results for the validation runs these results are poor probably due to limitations of the measurement equipment and the incapability of the model to simulate small events scenario analyses showed that forest as an alternative land use for the gully bottom will result in significantly lower water and sediment this strongly supports the implementation of the reforestation policy recently suggested and activated by the central government of the p r china

the barrier island system abstract barrier islands are part of a major coastal system composed of six interactive sedimentary environments the six environments are also elements needed to impose the designation barrier island on littoral sand bodies the elements are 1 mainland 2 backbarrier lagoon 3 inlet and inlet deltas 4 barrier island 5 barrier platform and 6 shoreface the morphodynamic and sedimentary evolution of each element affects adjacent environments as well as the entire system the interactive elements are defined and described by their morphologic sedimentologic and stratigraphic relationships to the barrier island and the barrier island system the stratigraphic relationships of the various elements of the system may be a valuable tool for paleogeographic reconstruction and sand body mapping

time constraints for the yellow river traversing the sanmen gorge 1 the yellow river is the second longest river in china a total course of 5464 km the yellow river traverses 30 gorges within its main course and the last one is the sanmen gorge the timing of cut through the sanmen gorge indicates the final integration of the yellow river previous geological surveys identify a paleolake in the weihe basin located west of the sanmen gorge the lake was drained when the gorge was cut through using cosmogenic nuclide burial dating we obtain ages of transition from lake to fluvial environments in the weihe basin and formation of fluvial terraces within the sanmen gorge the timing of cut through the sanmen gorge is constrained to 1 3 1 5 ma zircon u pb age distributions further suggest that the weihe the largest tributary of the yellow river running from west to east along the northern section of the qinling mountains primarily flowed over the sanmen gorge followed by the upper and middle yellow river traversing 1 3 1 4 ma ago it appears that formation and integration of the yellow river occurred in a short duration in the early pleistocene probably related to global climate changes

stratigraphy and internal structure of wind dominated barrier islands dune and machair of the outer hebrides scotland stratigraphy and internal structure of wind dominated barrier islands

hydrological responses and soil erosion potential of abandoned cropland in the loess plateau china recent changes in hydrological processes and soil erosion in the loess plateau china are immediate responses to cropland abandonment for revegetation which lead to a long term decrease in runoff generation and soil erosion however detailed hydrological responses and soil erosion changes have not been clearly evaluated in this study two issues were focused on the plot scale the first issue relates to changes in vegetation cover and soil properties during the early stages of revegetation given the occurrence of soil compaction it was hypothesized that runoff increased during this period and the soil erosion did not significantly decline even though vegetation increased the second issue is the effect of scale on runoff and soil erosion three plot groups of three vegetation types and two restoration stages were established for comparative experiments the results from these experiments confirmed that the soil compaction occurred during revegetation in this region greater runoff was produced in plot group that experienced both a longer restoration time and with higher vegetation cover such as groups 2 and 3 in this study than that with a shorter restoration time and lower vegetation cover group 1 in addition the total soil loss rates of all plot groups were rather low and did not significantly differ from each other this indicates that a reduction in runoff generation and soil erosion as a result of revegetation was limited in the early stages of restoration following the cropland abandonment with increasing plot area the runoff coefficient decreased for the plot group with a longer revegetation time groups 2 and 3 but gently increased for the one with a shorter restoration time group 1 in groups 2 and 3 soil loss rate decreased when plot area enlarged in group 1 it decreased before a plot area threshold of 18 m 2 was exceeded however the increase occurred when plot area crossed the threshold value in conclusion the high vegetation cover alone did not lead to reduction in the runoff coefficient during the early stages of revegetation when evaluating hydrological and soil erosion responses to revegetation the soil compaction processes should be considered additionally the effect of scale on runoff and soil erosion was found to be dependent on restoration extent and thus on restoration time c 2011 elsevier by all rights reserved

bacterial origin of iron rich microspheres in miocene mammalian fossils abstract in their taphonomic study of a cretaceous dinosaur fossil from the gobi desert mongolia kremer et al 2012 noted that the histological sections of this fossil preserved within their core iron oxide microspheres containing carbonaceous matter they interpreted the carbonaceous nature of these structures as organic matter and suggested a microbial origin probably bacterial for the structures microspheres similar both in composition and shape have been identified in fossils from cerro de la garita a miocene mammalian site in teruel spain in the latter case compact bone was also attacked by terrestrially associated bacteria microscopic focal destruction mfd which were enriched in iron and gives support to the idea that bacteria acted as the biological agent for iron precipitation during soft tissue decomposition in the early stages of bone diagenesis subsequent diagenetic episodes of mineralization related to the environmental context differ between these two sites calcite precipitation at the palaeo lakeshore of cerro de la garita and calcite and gypsum in the gobi desert study case of kremer et al 2012 if the microsphere is bacterial in origin it may be a useful taphonomic indicator of terrestrial exposure within a transitional environment of land and water

reconstructing taphonomic histories using histological analysis abstract recent years have seen rapid advances in the understanding of diagenetic changes to bone tissues and how these influence the chemistry microstructure and histological appearance of ancient bone it is now possible to recognise many characteristic features of diagenetically modified bone and this has led to the potential use of these parameters in estimating the potential survival of biogenic signals such as dna lipids proteins and stable isotopes these characteristic features also hold the potential for preserving a record of different post mortem environments in individual bones or assemblages of bones from the same site in sites where the burial conditions have changed over archaeological or geological timescales histological analyses can shed light on these different burial environments and permit the reconstruction of taphonomic histories of some bones examination of polished sections of bone using bse sem has been used to identify characteristic features attributed to aerobic soil bacteria cyanobacteria and sulphate reducing bacteria the approach shows promise for providing supplementary evidence when phasing complex sites such as graveyards which developed over several hundred years

rollover drowning and discontinuous retreat distinct modes of barrier response to sea level rise arising from a simple morphodynamic model we construct a simple morphodynamic model to investigate the long term dynamic evolution of a coastal barrier system experiencing sea level rise using a simplified barrier geometry the model includes a dynamic shoreface profile that can be out of equilibrium and explicitly treats barrier sediment overwash as a flux with barrier behavior primarily controlled by the maximum potential overwash flux and the rate of shoreface response the modeled barrier system demonstrates four primary behaviors height drowning width drowning constant landward retreat and a periodic retreat height drowning occurs when overwash fluxes are insufficient to maintain the landward migration rate required to keep pace with sea level rise on the other hand width drowning occurs when the shoreface response rate is insufficient to maintain the barrier geometry during overwash driven landward migration during periodic barrier retreat the barrier experiences oscillating periods of rapid overwash followed by periods of relative stability as the shoreface resteepens this periodic retreat which occurs even with a constant sea level rise rate arises when overwash rates and shoreface response rates are large and of similar magnitude we explore the occurrence of these behaviors across a wide range of parameter values and find that in addition to the maximum overwash flux and the shoreface response rate barrier response can be particularly sensitive to the sea level rise rate and back barrier lagoon slope overall our findings contrast with previous research which has primarily associated complex barrier behavior with changes in external forcing such as sea level rise rate sediment supply or back barrier geometry

can barrier islands survive sea level rise quantifying the relative role of tidal inlets and overwash deposition barrier island response to sea level rise depends on their ability to transgress and move sediment onto and behind the barrier either through flood tidal delta deposition or via overwash our understanding of these processes over decadal or longer timescales however is limited here we use a recently developed barrier island model brie to better understand the interplay between tidal dynamics overwash fluxes and sea level rise on barrier coasts and barrier island stratigraphy model results suggest that in microtidal environments with large alongshore sediment transport fluxes tidal inlets are ephemeral and migrate rapidly these conditions lead to effective deposition of flood tidal deltas and allow inlets to constitute most of the landward sediment flux whether barrier islands can survive sea level rise depends on the combined landward sediment flux from overwash and flood tidal delta deposition likely making barrier islands with artificially stabilized inlets via jetty construction or maintenance dredging more vulnerable to sea level rise

response of surface processes to climatic change in the dunefields and loess plateau of north china during the late quaternary this paper draws on recent optically stimulated luminescence osl dating to evaluate the long held assumption that dust accumulation rates in the loess plateau and the extent of active aeolian sand in the dunefields to the north have varied together over time because both are controlled by the strength of the asian monsoons and also possibly because the dunefields are proximal loess sources the results show there is little evidence that high rates of loess accumulation coincided with well dated episodes of extensive dune activity in the mu us otindag and horqin dunefields at 11 8 ka and 1 0 ka explanations for the apparent lack of coupling include local variation in the trapping of dust and post depositional preservation of the loess and dune sediments in response to varying local environmental conditions in addition a substantial portion of the loess may be transported directly from source areas where dust emission has somewhat different climatic and geomorphic controls than aeolian sand activity within the dunefields the results of this study cast doubt on the use of loess accumulation rate as a palaeoclimatic proxy at millennial timescale the dunefield and loess stratigraphic records are interpreted as primarily recording changes in effective moisture at a local scale but the timing of late quaternary dune activity along with a variety of other evidence indicates that moisture changes in many of the drylands of northern china may not be in phase with precipitation in core regions of the asian monsoons copyright 2011 john wiley sons ltd

microbial pathways and palaeoenvironmental conditions involved in the formation of phosphorite grains safaga district egypt abstract phosphatic grains of the shallow marine phosphorite deposits of egypt are classified as either phosphatic bioclasts preserving biological structure e g skeletal fragments such as fish bones and teeth or phosphatic peloids and intraclasts this study describes the destructive and constructive microbial pathways represented by bioerosion of bones by endolithic cyanobacteria and accretion of phosphatic peloids by bacteria the palaeoenvironmental conditions and post depositional diagenetic history of these grains have also been considered scanning and transmission electron microscopy showed that the phosphatic peloids under transmitted light microscopy are composed mainly of microspheres 0 5 to 2 5 m similar in shape and size to coccoid like bacteria chemical mapping showed that these microspheres are composed of carbonate fluorapatite cfa and surrounded by degraded carbonaceous matrix these grains are suggested to be reworked from pre existing microbial mats during transgressive regressive cycles affecting the southern tethyan campanian maastrichtian shallow continental shelf the bioerosion of phosphatic bones is characterized by a network of meandering microborings that penetrated inward from the bone surface by endolithic cyanobacteria the bioerosion of bones resulted in a gradual centripetal digestion and conversion of bones into micritic phosphate peloids the bioerosion mechanism is probably started in the acidic sheath surrounding cyanobacteria followed by supersaturation of po 4 and reprecipitation of crystalline cfa as electron dense remineralized rims electron microprobe microanalyses showed that the remineralized microbored areas are higher in cao p 2 o 5 and f and depleted in cl relative to unaltered bones a gradual demineralization of remineralized rims followed by dissolution of cyanobacterial cells is probably occurred during diagenesis and meteoric water alteration leaving behind empty microborings bone exposed to meteoric water alteration is lower in cao and p 2 o 5 and higher in f and cl than the unaltered bones understanding bone bioerosion has significant implications for palaeoenvironmental and taphonomic reconstruction archaeological applications and a regional correlation of the late cretaceous to palaeogene phosphogenic province extending from middle east to north africa

sediment supply from shoreface to dunes linking sediment transport measurements and long term morphological evolution a significant problem in current coastal research is the understanding of linkages between morphological phenomena occurring on different temporal and spatial scales morphodynamic processes in the nearshore typically exhibit nonlinear behaviour and consequently phenomena which occur on short temporal event scales as e g observed during field experiments have generally been difficult to upscale to provide an understanding of the long term behaviour of the coast on the time scale of seasons or decades this paper documents a persistent onshore migration of nearshore bar features over a period of 3 decades using a set of cross shore profile surveys from a barrier on the danish north sea coast the observed behaviour is consistent with experimental data obtained during weeklong field campaigns when sediment transport and bar migration were found to be landward directed during high energy dissipative conditions hydrodynamic and sediment transport processes leading to onshore bar migration and eventually welding of the bars are documented to provide an explanation for the observed long term evolutionary trends in addition bar welding and the resulting intertidal bar formation represent an onshore sediment storage which is subsequently available for aeolian transport observations on aeolian sediment transport indicate that transport rates and sediment supply to the foredunes critically depend on the presence of dry sand sources as represented by well drained intertidal bars measurements of long term accretion rates in foredunes indicate that volumes deposited on the crest and lee slope of the dunes are in reasonable correspondence with volumes supplied to the subaerial beach through the process of bar welding hence the data suggest that a persistent onshore directed sediment supply occurs from the shoreface across the surf and intertidal zones and into the dunes of the investigated barrier

barrier islands on bedrock a new landform type demonstrating the role of antecedent topography on barrier form and evolution barrier islands commonly occur in coastal plain and deltaic settings and a variety of behavioral and stratigraphic models exist in this paper a 90 km long barrier island system in the outer hebrides of scotland is identified for the first time uniquely among barrier islands the system rests directly on a planar bedrock gneiss surface a strandflat this bedrock surface has a profound influence on the morphology of the barrier island chain and exerts the dominant influence on barrier island form and evolution during transgression topographical irregularities on the bedrock surface control both plan and profile morphology of the barrier islands under sea level rise by barrier migration sediment is redistributed onshore and alongshore in a strongly three dimensional manner determined by topographic variability in the bedrock the barrier islands represent an endpoint in transgressive barrier island geomorphology that is controlled by the bedrock surface they are at the upper end of the recognized tidal amplitude for barrier islands the offshore wave regime is very high energy they lack a shoreface and neither ravinement surface nor transgressive sand sheet are developed sediment supply is dominated by offshore derived skeletal carbonate

plausible mechanisms for the boring on carbonates by microbial phototrophs photosynthetic microbes particularly cyanobacteria that bore into carbonates are ancient biological players in various geologic phenomena such as the destruction of biogenic carbonates and coastal limestones the reworking of carbonate sands and the cementation of microbialites their signatures are important tools for paleoenvironmental reconstruction and they play a significant role in marine aquaculture in spite of their geologic environmental and economic importance the mechanism by which they are able to excavate calcareous and calcophosphatic mineral substrates remains unknown excavation by acidulation commonly thought to be a possible mechanism constitutes nothing less than an apparent paradox in that the geochemical consequence of oxygenic photosynthesis should be carbonate precipitation not dissolution three alternative mechanistic models are presented here that may allow cyanobacterial boring to proceed and be still consistent with available evidence as well as microbiological and geologic geochemical principles they are based on either temporal or spatial separation of photosynthesis and respiration and on the active extrusion of calcium ions through an active cellular uptake and transport process from the three models the latter is shown to be most appropriate in describing and explaining the boring phenomenon several experimental approaches are discussed that would be appropriate to elucidate the paradox

light at the end of the tunnels the origins of microbial bioerosion in mineralised collagen abstract microbial bioerosion in all its manifestations is one of the major factors determining the long term survival of archaeologically and environmentally important artefacts and ecofacts made from mineralised collagen bones antler teeth and ivory the bone diagenesis literature contains extensive descriptions of different morphologies and classifications of microbial bioerosion microscopical focal destruction wedl tunnels linear longitudinal budded and lamellate tunnelling etc but the causative agents remain to be discovered palaeontologists are in a similar situation when describing ichnofossils where bioerosion is classified by its characteristic morphology and only tentatively assigned to specific causes in archaeological bones wedl tunnels have traditionally been ascribed to fungi but a re examination of wedl s original paper and subsequent literature has shown that all the early specimens examined came from aquatic environments and that euendolithic microflora cyanobacteria or chlorophytes might have been responsible these microorganisms are known to tunnel into marine shells linear longitudinal budded and lamellate tunnelling have all been ascribed to bacteria however analyses using a combination of backscatter sem bsem and mercury intrusion porosimetry hgip of bones excavated from terrestrial soils suggest that the various tunnelling morphologies described by earlier researchers are actually all manifestations of a single architecture the differences arising from the inherent variability of bone microstructure and the hydrology of the burial environment an examination of the bsem and hgip data also indicates that the bacteria responsible may spread through dead bone tissues by expanding the canalicular network or dentinal tubules in teeth rather than creating new tunnels long term field burial experiments using de fleshed cow bone specimens have now demonstrated that bacterial tunnelling develops over decades rather than months as was previously thought even in warm tropical soils this has obvious implications for the origin of the bacteria responsible soil bacteria versus endogenous gut bacteria since the bone specimens were quickly isolated from gut contents although no attempt is made here to identify a specific organism or organisms responsible for tunnelling in terrestrial archaeological bones a tentative model is proposed for how cycles of wetting and drying or changes in local dissolved oxygen levels could lead a common gram positive soil bacterium to produce the pattern of bacterial bioerosion seen in exhumed bones this soil organism may act in a similar way to staphylococcus aureus which proliferates in living bone causing osteomyelitis by infiltrating and enlarging the canalicular network

influence of inherited geologic framework on barrier shoreface morphology and dynamics abstract passive margin coastlines with limited sand supplies such as much of the u s atlantic margin are significantly influenced by the geologic framework of older stratigraphic units that occur beneath and seaward of the shoreface many u s east coast barrier islands are perched barriers in which the underlying pre modern sediments determine the morphology of the shoreface and strongly influence modern beach dynamics and composition perched barriers consist of varible layers of beach sand on top of older eroding stratigraphic units with highly variable compositions and geometries along many parts of the coastal system stratigraphically controlled bathymetric features on the inner shelf modify waves and currents and thereby effect patterns of sediment erosion transport and deposition on the adjacent shoreface it is essential to understand this geologic framework before attempting to model the large scale behavior of these types of coastal systems in north carolina most shoreline features are controlled by the pre holocene stratigraphic framework of the shoreface the beaches are perched on top of pre existing pleistocene tertiary and cretaceous sediments the surficial geology of the coastal zone is subdivided into two distinct provinces resulting in different stratigraphic controls of the shoreface north of cape lookout the geological framework consists of a quaternary sequence that fills a regional depositional basin called the albemarle embayment the coastal zone south of cape lookout is dominated by tertiary and cretaceous units that crop out across the coastal plain and continental shelf with very thin quaternary units only locally preserved superimposed upon this regional stratigraphy is an ancient drainage system resulting in a series of fluvial valleys filled with younger coastal sediments separated by large interfluve areas of older stratigraphic units this results in a coastal system in which the shoreface is either nonheadland or headland dominated respectively headland dominated shorefaces are further divided into subaerial and submarine categories nonheadland dominated shorefaces are further divided into those influenced primarily by transgressive or regressive processes or channel dominated depositional processes i e inlet migration or stream valley fill examples of each of these six types of shorefaces are presented to demonstrate the control that the geologic framework exhibits on shoreface morphologies and processes

mesoscale geomorphic change on low energy barrier islands in chesapeake bay u s a this paper presents an analysis of decadal mesoscale geomorphic change on sandy barrier islands in thefetch limited environment of chesapeake bay low energy barrier islands exist in two settings on the fringe of marshes and in open water and this analysis shows the various types of barrier island to be genetically related barrier islands that face the dominant wind and wave direction e or w retreat via barrier translation preserving the barrier island volume those that exist in re entrants are dominated by longshore transport processes are strongly affected by sediment supply and are subject to disintegration marsh fringe barrier islands are perched on or draped over the surface of the underlying marsh they migrate landwards via barrier translation during periodic high water events accompanied by large waves hurricanes and northeasters the underlying marsh surface erodes under all water levels and the rate of retreat of the barrier island and underlying marsh may take place at different rates leading to various configurations from perched barrier islands several metres landward of themarsh edge to barrier islands that have a sandy shoreface extending into the subtidal zone the coastal configuration during landward retreat of marsh fringe barrier islands is subject to strong local control exerted by the underyling marsh topography as erosion ofmarsh promontories occurs and marsh creeks are intersected and bypassed the configuration is subject to rapid change periodic sediment influxes cause spits to develop at re entrants in themarsh the spits are initiated as extensions of adjacentmarsh fringe barrier islands but as the sediment volumeis finite the initial drift aligned spits become sediment starved and begin to develop a series of swash aligned cells as they strive formorphodynamic equilibrium the individual cells are stretched until breaches form in the barrier islands creating inlets with tidal deltas at this stage the low energy barrier islands closely resemble open ocean barrier islands continued reworking leads towidening of the inletswith consequent loss of constriction of tidal flow the tidal deltas are thus no longermaintained and ultimately the island systemdisintegrates through inlet widening and is transformed to subtidal shoals barrier islands at various stages in this evolutionary cycle can be observed around the bay mid bay barrier islands are affected by wave processes from both sides this helps maintain the barrier island form and enables barrier islands to persist as sediment is exchanged between both sides of the island rates of barrier island translation are extremely high up to 30 m year over a 12 year period this is attributed to the lowvolume of sand which facilitates complete rollover in short periods accelerated sea level rise is likely to hasten the translation rates ofmarsh fringe barrier islands the rapid disintegration ofmost spits compared to the persistence of marsh fringe barrier islands points to a reliance on the marsh as a stabilising point if the marshes are overstepped by rising sea level as appears to be happening the complete disintegration of the barrier islands is highly likely

measurements and relationships of diagenetic alteration of bone from three archaeological sites four diagenetic parameters have been chosen to represent the state of diagenesis of bone buried on archaeological sites they are histological preservation protein content crystallinity and porosity how these parameters are measured is described and results from populations of bones from three different sites are presented the results show the extent and variation in the degree of change both within a site and between sites in particular the correlations between diagenetic parameters are examined which give clues about the processes which cause alteration the value of porosity determinations both at the intercrystalline level and at coarser levels in revealing the degree of diagenetic change in bone and in underlying the dynamics of the interaction between buried bone and the surrounding water is stressed the data also indicate but are too restricted to prove the following microbiological attack is generally complete within less than 500 years substantial levels of protein may remain in bone after maximal micromorphological alteration loss of protein appears to be independent of other diagenetic change the correlated lose of microporosity with increase of crystallinity suggests these changes may arise from the dissolution perhaps with subsequent recrystallization of the smallest hydroxyapatite crystallites

use of landslide dammed lake deposits and pollen tracing techniques to investigate the erosional response of a small drainage basin in the loess plateau china to land use change during the late 16th century a major landslide that occurred in 1569 in the huangtuwa gully catchment within the rolling loess plateau region of china resulted in the creation of a landslide dammed lake at the outlet of the small 0 1 km2 tributary valley of the houxiaotan gully all the sediment transported to the outlet of this catchment was deposited in the lake after about 30 years the dam failed and the lake deposits were dissected as the stream cut down to its former base level substantial remnants of the sediment deposits that accumulated over the ca 30 year period are however preserved as terraces near the outlet of the catchment and a vertical section through these sediment deposits was investigated using stratigraphic and pollen tracing techniques individual flood couplets could be clearly distinguished and these permitted the establishment of a chronology for the sediment deposits and the estimation of the sediment yields associated with individual events and individual years pollen analysis undertaken on samples collected from the individual flood couplets also provided information on the variation of the pollen content of the sediment and the proportion of artemisia pollen during the period represented by the deposits interpretation of the information assembled from the sediment section has made it possible to reconstruct the erosional history of the houxiaotan catchment during the 31 year period following the landslide the average sediment yield of the catchment in the late 16th century was very similar to its present day sediment yield the sediment yield from the catchment and the relative contribution of the inter gully areas as compared to the gully system declined immediately after the landslide as a result of abandonment of the cultivated land within the catchment the restoration of cultivation in the catchment after about 17 years resulted in an increase in sediment yield from ca 9000 t km 2 yr 1 to ca 30 000 t km 2 yr 1 and a substantial increase in the proportion of sediment contributed by the cultivated inter gully areas scope exists to apply a similar approach to the sediment deposits that accumulated in other former landslide dammed lakes within the rolling loess plateau region of china in order to develop an improved understanding of the erosion history of the region

erosion processes and landform evolution on agricultural land new perspectives from caesium 137 measurements and topographic based erosion modelling despite growing interest in soil erosion on agricultural land relatively little attention has been paid to the influence of erosion processes on the pattern of contemporary landform evolution this in part reflects the problems associated with upscaling the results of short term process studies to temporal and spatial scales relevant to the study of landform evolution this paper presents a new approach to examining the influence of erosion processes on landform evolution on agricultural land which employs caesium 137 cs 137 measurements to provide medium term c 40 years estimates of rates of landform change experimental data and a topographic based model to simulate soil redistribution by tillage a mass balance model of cs 137 redistribution to separate the water erosion and tillage components of the cs 137 signatures and field observations of water erosion for validation this approach is used to examine the relative importance of water erosion and tillage processes for contemporary landform evolution at contrasting sites near leuven in belgium and near yanan in shaanxi province china this application of the approach provides good agreement between the derived water erosion rates and field observations and hitherto unobtainable insights into medium term patterns and rates of contemporary landform evolution at huldenberg in belgium despite rill incision of slope concavities and ephemeral gully incision of the valley floor contemporary landform evolution is dominated by infilling of slope and valley concavities rates 0 5 mm a 1 and gradual lowering of slope angles as a result of tillage in contrast at ansai near yanan the slope is characterized by increase in slope angle over most of the length recession of the steepest section at a rate 5 mm a 1 and by increasing planform curvature at this site contemporary landform evolution is dominated by water erosion the constraints on the approach are examined with particular attention being given to limitations on extrapolation of the results and to the sensitivity of the models to parameter variation c 1997 by john wiley sons ltd

depositional controls on a hypertidal barrier spit system architecture and evolution pointe du banc spit north western france physical stratigraphy architecture and evolution of barrier systems in hypertidal environments tidal range above 6 m are understudied and depositional controls are poorly understood compared with wave dominated barrier systems and barrier spits in microtidal mesotidal and macrotidal settings based on vibracores ground penetrating radar radiocarbon and optically stimulated luminescence age data the formation and evolution of the hypertidal barrier system of pointe du banc north western france has been reconstructed the study shows that the barrier spit has a complex composite sedimentary architecture consisting of wave dominated and tide dominated sedimentary bodies a morpho sedimentary model is presented that demonstrates how barrier spit progradation resulting from littoral drift was the main manner of spit elongation whereas sediment convergence caused by landward migration of swash bars and seaward migration of tidal dunes caused the spit terminus to grow in height and width these results suggest that long term accretion rates varied considerably in response to changes in sediment supply variations in storminess together with the large scale topography of the coast controlled the sediment supply and thus the evolution of the barrier system during latest holocene despite architectural complexity hypertidal barrier systems preserve records of past climate changes

diagenesis of archaeological bone and tooth an understanding of the structural complexity of mineralised tissues is fundamental for exploration into the field of diagenesis here we review aspects of current and past research on bone and tooth diagenesis using the most comprehensive collection of literature on diagenesis to date environmental factors such as soil ph soil hydrology and ambient temperature which influence the preservation of skeletal tissues are assessed while the different diagenetic pathways such as microbial degradation loss of organics mineral changes and dna degradation are surveyed fluctuating water levels in and around the bone is the most harmful for preservation and lead to rapid skeletal destruction diagenetic mechanisms are found to work in conjunction with each other altering the biogenic composition of skeletal material this illustrates that researchers must examine multiple diagenetic pathways to fully understand the post mortem interactions of archaeological skeletal material and the burial environment

barrier island evolution middle atlantic shelf u s a part i shoreface dynamics abstract in part i of this paper near bottom fluid velocity and sediment concentration measurements from the shoreface of a middle atlantic barrier long island coast are analyzed to provide insight into the dynamics of erosional shoreface retreat in part ii these data are combined with observations of coastal stratigraphy in order to construct a model for the evolution and behavior of middle atlantic barriers wave motions on the long island shoreface tend to drive sediment onshore calculations of the onshore sediment flux driven by asymmetrical shoaling waves show that for the wave states commonly encountered on the middle atlantic shelf values become strongly positive landward of approximately 10 m water depth upper shoreface but drop to very low values shortly seaward of that isobath on the lower shoreface and inner shelf floor fair weather wave current interaction tends to cause a landward creep of sediment even though the wave orbital component of the near bottom velocity field is nearly symmetrical this movement occurs because the wave approach direction generally lies within 90 of the direction up coast or down coast of the alongshore wind driven current therefore fluid shear stress acting on the sediments tends to be reinforced during the shoreward stroke of the wave orbital motion and partially cancelled during the seaward stroke during major storms the rate of sediment transport increases by at least an order of magnitude and the role of wind driven currents becomes important much more sediment is resuspended by the wave orbital current component because storm waves are more powerful than fair weather swells but the wind driven flow component is also much stronger and is now available for transporting the resuspended sediment storm flows over the shoreface occur in distinct dynamic zones surf zone friction dominated zone transition zone geostrophic zone the zones are defined by dynamical considerations and expand or contract with the intensity of the causative wind stress during peak flow events the characteristic length scales of the friction dominated and geostrophic zones tend to correspond with the morphologic zones of the shoreface and inner shelf the storm intensified wind driven alongshore flows of the lower shoreface are frequently jet like in nature and may be upwelling or downwelling wind driven coastal flows with a strong downwelling component occur during most storms on the long island coast and are particularly important to the coastal sand budget during these events sand is entrained by the storm intensified upper shoreface circulation system of wave driven alongshore currents and rip currents and is fed into the main wind driven coastal current because of the offshore component of bottom flow sand is swept down the lower shoreface and onto the adjacent inner shelf fair weather processes may be unable to return storm deposited sand to the beach from such an offshore position the shoreface transport regime of the long island barrier coast thus consists of long periods of time months during which sand moves slowly toward the beach punctuated by short intense periods hours or days during which sand is transferred from the shoreface to the adjacent inner shelf the long term sense of movement of the shoreface whether retreating the long island case or prograding must depend on the loss or gain of sand by shoreface with respect to the inner shelf the data shows that the coastal sand budget is controlled not only by the upper shoreface cycle withdrawl of sand from the beach prism storage in the breakpoint bar and its subsequent return to the beach but by a cycle of larger spatial and temporal scale in which sand is exchanged between the shoreface as a whole and the adjacent inner shelf

geomorphic response type model for barrier coastlines a regional perspective based on quantitative documentation of historical changes in shoreline position between 1847 and 1991 eight geomorphic response types were established for classifying megascale changes along barrier coastlines 1 lateral movement 2 advance 3 dynamic equilibrium 4 retreat 5 in place narrowing 6 landward rollover 7 breakup and 8 rotational instability long term decades to centuries monitoring of shoreline position over a spatial scale of 10 to 100 km provides a scientific basis for documenting process response relationships that shape regional coastal morphodynamics although megascale shoreline change studies often are lacking this type of information is critical for developing realistic research and management strategies regarding form process relationships in coastal depositional systems the spatial distribution of geomorphic response types is delineated along the barrier coastlines of louisiana mississippi and southern georgia northern florida at megascale the rate of relative sea level rise along these barrier coastlines appears to be one of the major factors controlling the occurrence of geomorphic response types however sediment supply exerts significant influence on shoreline response as well

review of electromagnetic induction for mapping barrier island framework geology abstract the geologic framework controls on modern barrier island transgression and the relationship of these controls to subsurface structure hydrology and island geomorphology are not well understood recent evidence suggests that alongshore variations in pre holocene geology of barrier islands modify nearshore hydrodynamic processes and sediment transport ultimately affecting how barrier islands will respond to relative sea level rise explorations of holocene barrier island geology are usually based on cores to supplement bathymetric onshore offshore seismic and or ground penetrating radar gpr surveys the advantages and limitations of these methods with respect to barrier island investigations are briefly described in this review alternative near surface geophysical methods including electromagnetic induction emi sensors are increasingly being used for coastal research because they are non invasive provide continuous subsurface information across a variety of sub environments and are capable of characterizing large areas in a short time although these emi sensors have shown promise in coastal applications a number of issues primarily related to subsurface hydrology need to be addressed to fully assess the limitations of this technique this paper reviews the theory methodology and applications of emi in support of geologic framework studies with particular reference to barrier islands resolution of these issues will allow emi sensors to complement and offer significant advantages over traditional methods in support of an improved understanding of large scale barrier island evolution

use of reservoir deposits to reconstruct the recent changes in sediment yields from a small granite catchment in the yimeng mountain region china information on recent changes in sediment yields from small catchments provides a better understanding of temporal trends in soil loss from certain physical and human influenced landscapes that have been subjected to recent environmental changes and will help bridge the current knowledge gap that exists between hillslope erosion and sediment transport in rivers the yimeng mountain region characterized by alternating granite and limestone is one of the most susceptible regions to soil erosion in northern china and has been subjected to intensive anthropogenic activity in recent years soil loss from areas underlain by granite is particularly obvious and is the main sediment source for the yihe river in this study we used reservoir deposits to estimate the changes in sediment yields over the past 50 years from a small catchment underlain by granite namely the jiangzhuang catchment in the yimeng mountain region three cores were collected from the jiangzhuang reservoir in the catchment the activities of 137cs and 210pbex at different depths clay grain size 5 m contents and sedimentary organic carbon soc contents in the cores were analysed with reference to human activity and environmental change in the catchment the chronologies of the cores were established by 137cs and 210pbex dating the area specific sediment yield ssy for different time periods since dam construction was estimated from each core by referring to the original capacity curve of the reservoir the results indicate that the depth profiles of 137cs 210pbex clay and soc contents in cores from the jiangzhuang reservoir reflect the general history of human disturbances on the catchment over the past 50 years the estimated ssy value from each core for each period ranged from 7 2 2 7 to 23 7 8 3 t ha 1 y 1 with a mean of 12 5 4 6 t ha 1 y 1 ssy decreased during 1954 1972 and then showed a general tendency to increase the temporal pattern of the sediment yield largely reflects the history of environmental change influenced by human activity in the catchment

sustained high magnitude erosional forcing generates an organic carbon sink test and implications in the loess plateau china bation of the land ocean carbon flux nevertheless the net effect of these lateral carbon fluxes on the c cycle is poorly constrained and there is no consensus as to whether they drive a net source or net sink of atmospheric co2 here we test the hypothesis that under sustained erosional forcing soil carbon stocks on hillslopes reach a new equilibrium state in which all carbon exported with erosion is replaced and therefore erosion results in a net sink for atmospheric co2 at the scale of eroding hillslopes the evidence from our study site in the loess plateau of china is consistent with this hypothesis despite net export of oc equivalent to ca 10 npp we found that all of the eroded oc was replaced and therefore that the sink strength was equal to the c export rate this sets the upper limit of the erosion induced sink term at the scale of whole watershed the fate of the exported carbon in reservoirs floodplains riverbeds and the ocean ultimately controls the watershed scale sink strength nevertheless the full replacement observed here suggests that erosion does not induce a c source irrespective of the fate of the exported carbon at least for high input agricultural systems finally we propose that assessment of the c cycle perturbation associated with erosion induced lateral c fluxes must be made an integral part of accounting mechanisms for climate change mitigation strategies that are based on land use change and c sequestration in terrestrial environments

spatial variation in soil soc and total n redistribution on affected and non affected slope terraces due to the 8 0 wenchuan earthquake in 2008 by using 137cs technique abstract using the 137 cs technique we assessed spatial variation in soil erosion and its impact on lateral movements of soil organic carbon soc and total nitrogen total n in a terraced series and a complex slope in the longmenshan fault zone china the complex slope derived from three terraced fields with damaged banks resulting from the 8 0 wenchuan earthquakes in 2008 the terraced series and complex slope are the dominant sloping farmland patterns in this area which represent for earthquake non affected and affected sloping farmland respectively soil loss occurred over the upper parts of slopes and deposition occurred towards the downslope boundary of each terrace also soil loss occurred on upper terraces and soil accumulation on lower terraces net soil erosion rates for the terraced toposequence were estimated at 3 70 14 38 mg ha 1 yr 1 indicating the terraced toposequence played an important role in soil conservation for the complex slope higher soil erosion rates occurred at the summit and other slope positions with greater slope curvature and soil accumulation occurred at the toe slope and other slope positions with lower slope curvature 15 m 25 m and 40 m in addition to water erosion collapses resulting from earthquake and tillage erosion were also important soil erosion processes for the complex slope moreover net soil erosion rate on the complex slope 4 89 18 03 t ha 1 yr 1 was significantly higher than on the terraced series soc and total n inventories showed similar patterns to the 137 cs inventory such results confirm that 137 cs can help to trace soc and total n dynamics on sloping farmland in this area

soil erosion rates on sloping cultivated land on the loess plateau near ansai shaanxi province china an investigation using 137cs and rill measurements sediment yields from the rolling hills area of the loess plateau in northern china 10 000 25 000 t km 2 yr 1 are amongst the highest in the world the sediment is believed to derive from both the deep gullies that dissect the rolling plateau and the steep cultivated fields on the slopes of the mounds between the gullies however there are few reliable data for erosion rates on the cultivated fields and it is suspected that current estimates 10 000 16 000 t km 2 yr 1 based on empirical relationships derived from erosion plot studies exceed the true values this study sought to address the need for more information concerning erosion of the cultivated fields through derivation of erosion rates from measurements of rill volume and caesium 137 cs 137 inventories for typical fields near the village of ansai shaanxi province the derived erosion rates are discussed and compared with estimates based on empirical relationships derived from erosion plot data where erosion rate estimates based on both rill volume data and cs 137 inventories are available they show good agreement in the pattern of downslope variation both show a sharp decline in erosion rates at a slope length of c 50 m this is tentatively attributed to a change from transport limited to detachment limited conditions where rill incision reaches the undisturbed loess at the base of the plough layer no such decline is visible in the predictions based on empirical relationships derived from erosion plot data further evidence is presented that supports the suggestion that these empirical relationships overestimate erosion rates at slope lengths in excess of c 50 m it is tentatively suggested that the rates of soil erosion from sloping cultivated fields in the rolling hills area are more likely to lie in the range 8000 10 000 t km 2 yr 1 than in the higher range suggested by the empirical relationships c 1998 john wiley sons ltd

sources of alluvium in a coastal plain stream based on radionuclide signatures from the 238u and 232th decay series ratios 226 ra 232 th 226 ra 230 th and 230 th 232 th channel alluvium indicates a transition from interfluve surface to subsoil sources during flood subsoil 34 to 91 over about 8 km and bank full stages subsoil 9 to 74 over about 12 km with distance downstream these results indicate strong coupling between hillslope and channel processes reflecting land use change from forested to agricultural concentrated in lower loco bayou this methodology shows that sediment sources can be differentiated based upon landscape placement where lithologic contrast is absent the geochemistry long halflives and fractionation of 238 u and 232 th decay series radionuclides during pedogenic and fluvial processes in humid climates suggest that these methods are applicable in a wide variety of fluvial systems index terms 1040 geochemistry isotopic composition chemistry 1803 hydrology anthropogenic effects 1815 hydrology erosion and sedimentation 1824 hydrology geomorphology 1625 keywords natural radionuclides fingerprinting alluvium source apportioning

bedrock controls on barrier island development west central florida coast abstract fifty vibracores and 130 km of high resolution seismic profiles were taken in the lagoons and nearshore area of northern pinellas county florida to determine the role of antecedent topography upon barrier island location origin and development east west seismic profiles show a terrace with 1 1 5 m of relief located along the seaward trend of the barrier islands between 4 and 6 m msl this antecedent topography is composed of a relatively erosion resistant miocene limestone and the terrace is usually present as an increase in slope a contour map of the pre holocene surface shows that this subsurface feature is continuous along the entire study area and is mimicked by the opposing orientations of honeymoon and caladesi islands the correspondence of the modern barrier system to the antecedent topography indicates that 1 the islands formed on the terrace or that 2 landward migration of the barriers was stopped by grounding on this feature stratigraphic analyses of lagoonal and nearshore environments were conducted in order to establish the overall response of the northern pinellas coastal system to the late holocene sea level rise this analysis indicates a basically transgressive holocene sequence with lagoonal sediments occurring seaward of the islands underlying the lagoonal deposits in all areas is a 1 m thick relict pleistocene unit that has been flooded reworked and vegetated by intertidal to subtidal organisms a model of development for these barriers is proposed which incorporates an early transgressive history followed by a recent progradational phase the progradational phase was probably initiated by the late holocene slowdown in sea level rise and an increased sediment supply as the barrier islands migrated over a relict sediment source the antecedent topography thus served as a stabilization point for landward barrier migration and seaward progradation the antecedent topographic control of barrier island location described by this model is dependent upon the coincident decline in the rate of sea level rise and an increased sediment supply

dental histology of late miocene hipparionins compared with extant equus and its implications for equidae life history abstract hipparionins were a dominant element of the late miocene faunas of europe however their biology and ecology remain incompletely understood in this paper we explore the pace of life history of different sized hipparionin horses using dental histology and compare it with extant equids in doing so we consider i the size diversity of hipparionins ii their generally smaller size compared to extant equids and iii the allometric coupling between size and life history in particular we reconstruct the dental growth in lower first second molars and in later formed lower third molars for three hipparionin taxa two dwarf species hipparion periafricanum and h gromovae and a larger species h concudense we also analyze dental growth in an extant zebra equus quagga for comparative purposes our results reveal that within each species there are differences in enamel growth parameters between the first second molars and third molars these results illustrate the differences in the developmental timing of these teeth and the existence of a relationship between dental growth parameters with somatic growth we also find that hipparionin teeth grow at slower rates and tend to erupt later in time than in extant equus dwarf hipparionins moreover exhibit lower enamel extension rates than the larger species but similar formation and eruption times considering the link between dental development and life history these results suggest a slower pace of growth of selected hipparionins compared to extant equids and a further slower life history than expected for their size in the two dwarf forms