predictive modeling of slope deposits and comparisons of two small areas in northern germany abstract methods for correct quantitative comparison of several terrains are important in the development and use of quantitative landscape evolution models and they need to introduce specific modeling parameters we introduce such parameters and compare two small terrains with respect to the link slope valley for the description of slope deposits colluvium in them we show that colluvium accumulation in small areas cannot be described by linear models and thus introduce non linear models two small areas perdoel 0 29 ha and bornhoved 3 2 ha are studied slope deposits in the both are mainly in dry valleys with a total thickness m total up to 2 0 m in perdoel and up to 1 2 m in bornhoved parent materials are mainly pleistocene sands aged 30 kyr bp exponential models of multiple regression that use a 1 m lidar dem digital elevation model explained 70 93 of spatial variability in m total parameters dh 12 and dv 12 of horizontal and vertical distances are introduced that permit to characterize and compare conditions of colluvium formation for various terrains the study areas differ 3 7 times by the parameter dh 12 that describes a horizontal distance from thalwegs at which m total diminishes 2 72 times dh 12 is greater in bornhoved 29 7 m than in perdoel 8 12 m we relate this difference in dh 12 to the distinction between types of the link slope valley a regional type if catchment area of a region outside a given small area plays an important role and a local type when accumulation of colluvium from valley banks within a small area is of more importance we argue that the link slope valley is regional in perdoel and local in bornhoved peaks of colluvium thickness were found on thalwegs of three studied valleys by both direct measurements in a trench and model surfaces of m total a hypothesis on the formation mechanism of such peaks is discussed the parameter dv 12 describes a vertical distance from a peak of colluvium thickness along valley bottom at which m total diminishes 2 72 times values of this parameter differ 1 4 times for the study areas dv 12 is greater in perdoel 3 0 m than in bornhoved 2 1 m thus indicating more sharp peaks of m total in bornhoved exponential models allow construction of predictive maps of buried pleistocene surfaces for both the terrains and calculate colluvium volumes with an error 4 2 for perdoel and 7 1 for bornhoved comparisons of buried and present surfaces showed that the latter are more smoothed more strongly in valleys where flow branching is increased

phases of soil erosion derived colluviation in the loess hills of south germany in south germany soil erosion is as old as farming and dates back to early neolithic times its sedimentary products form thick colluvial and alluvial sediment bodies in all drainage basins numerous local studies exist but the extrapolation of findings from local case studies to a regional scale has been problematic here a graphical approach is used for frequency analysis of existing data a frequency distribution for optical dates on colluvial sediments from the beginning of agriculture until 1200 ad was constructed by 1 representing the optical ages by gaussian distributions and 2 summing all the single curves the resulting graph clearly shows phases of increased colluviation during periods of stronger human impact a first significant increase occurred during the bronze age during the iron age roman period and at around 800 ad distinct maxima appear in the distribution and highest frequencies are present towards the end of the analysed period at around 1100 ad conclusions that can be drawn from such an approach are limited by sampling bias and other factors but for the analysed period and on a regional and long term scale colluviation seems to have been mainly triggered by intensity of land use climatic fluctuations are of only secondary importance rainfall events that were sufficiently erosive to produce colluvial sediments occurred throughout the agricultural periods the limiting factor for colluvium production was sensitivity of the landscape to erosion and this is a result of land use d 2002 elsevier science b v all rights reserved

chromium and nickel as indicators of source to sink sediment transfer in a holocene alluvial and coastal system po plain italy abstract a reliable quantitative estimate of changes in source to sink sediment transfer requires that high resolution stratigraphic studies be coupled with accurate reconstructions of spatial and temporal variability of the sediment routing system through time source to sink patterns from the contributing upland river catchments to the deltaic and coastal system are reconstructed from the holocene succession of the po plain on the basis of selected geochemical indicators sediment supplied to the delta area by the major trunk river the po exhibits naturally high cr and ni values which invariably exceed the maximum permissible concentrations for unpolluted sites this anomaly reflects remarkable sediment contribution from ultramafic ophiolitic parent rocks cropping out in the po drainage basin western alps and nw apennines in contrast alluvial and coastal plain deposits supplied by ophiolite free apenninic catchments invariably display lower cr and ni contents for constant sediment provenance domain cr and ni distribution is observed to be controlled primarily by hydraulic sorting clay silt deposits floodplain swamp and lagoon bay facies associations invariably show higher metal concentrations than their sandy counterparts fluvial channel distributary channel and beach ridge facies associations from a stratigraphic perspective in sedimentary basins characterized by strong differences in sediment composition geochemical fingerprinting of individual facies associations framed by surfaces of chronostratigraphic significance is proposed as an invaluable approach towards an accurate quantitative assessment of sediment storage in alluvial and coastal depositional systems as opposed to volumetric reconstructions based on lithologic or geometric criteria alone

inferring mean rates of sediment yield and catchment erosion from reservoir siltation in the kruger national park south africa an uncertainty assessment abstract reservoir siltation surveys facilitate the quantification of the mean area specific sediment yield ssy of catchments for decadal and longer time spans this requires information on the volume vs and dry bulk density dbd of reservoir deposits the period of time tr during which they were accumulated the reservoir sediment trap efficiency te and the catchment area a for the calculation of the catchment wide average rate of erosion by water e the sediment delivery ratio sdr of the catchment needs to be estimated each step in this workflow represents a potential source of uncertainty here we explore the extent to which individual error sources contribute to uncertainties in ssy and e values mean ssy and e values are inferred for small to medium sized catchments 100 km2 of 15 small 350 103 m3 intermittently dry reservoirs located in the southern kruger national park and observation periods of 30 to 65 yr mean relative uncertainties of resulting ssy and e values amount to 21 and 46 at the 95 confidence level respectively uncertainties in ssy values arise mainly from the te estimation mean fractional uncertainty contribution of 64 while the sdr estimation is the major cause 79 for uncertain e values uncertainties in the determination of vs and dbd values are rather unimportant contributing together

a 14 000 year sediment yield record from western germany based on annually laminated lake sediments the reconstruction of sediment yield data for the catchment of lake holzmaar 205 8 ha in the eifel mountains western germany is based on high resolution geochemical and physical analyses of an absolutely dated sediment record this technique provides flux rates of allochthonous minerogenic deposition for the last 13 840 years the pleistocene holocene transition is characterized by instable soils and vegetation caused by adjustment of the catchment to interglacial climatic conditions these instabilities are the reason for elevated mean sediment yields in the catchment of 16 t km 2 yr 1 until 9800 cal bp during most of the holocene erosive processes are insignificant and sediment yields are very low 1 5 t km 2 yr 1 since humans cleared the forests for agriculture and early industrial purposes the natural environment has been disturbed and sediment yields increased to mean values of 14 t km 2 yr 1 during the last 2750 years comparisons of reconstructions from the eifel area with similar data from southern sweden and with measured data from lakes reservoirs and monitoring sites suggest that quantitative reconstructions based on lake holzmaar sediments may be regarded as reliable despite uncertainties related to the methods of reconstruction applied

single quartz grain electron spin resonance esr dating of a contemporary desert surface deposit eastern desert egypt abstract signal resetting by sunlight prior to burial is a crucial assumption in electron spin resonance esr dating of sediments this resetting process is expected to be completed to a greater extent in arid than in fluvial environments the present paper investigates the natural and artificially irradiated signal intensity of ti related centres in single quartz grains collected from the desert surface eastern desert egypt in order to test this hypothesis the results suggest that in most grains both the ti li and ti h signal are completely reset to zero additive dose curves based on the sum of both ti centres show an anomaly in the low dose region possible causes for this behaviour are briefly discussed three fitting procedures are conducted and each of them shows a different palaeodose distribution with a rather large spread in d e values it is concluded that similar fossil deposits would be datable by single grain esr using q band measurements of the ti li or ti h signals in quartz

long term development of holocene and pleistocene gullies in the protva river basin central russia abstract the specific geomorphic structure a combination of flat or gentle watersheds with short steep valley sides and the high resistance of surface material in the case study area in the centre of the russian plain are responsible for the specific pattern of holocene erosion no or minor sheet erosion the occasional appearance of new gullies on the valley sides four out of 19 studied and a concentration of erosion activity in old gullies that had existed since pre holocene times 15 out of 19 studied the erosion activity is studied using radiocarbon dating of gully sediments summed probability density distribution spdd of 65 radiocarbon dates is applied to detect changes of erosion rates over the last five millennia three millennium scale phases of erosion activity are distinguished phase 1 1200 years bp to the present intensive erosion phase 2 2800 to 1200 years bp weak erosion and phase 3 4800 to 2800 years bp intensive erosion short episodes or single events of relatively strong erosion have been found at around 4700 3800 3000 2200 1800 and 900 years bp erosion during phase 3 coincided with the holocene lowest population density in the whole region and the start of phase 1 coincided with a population gap at the case study area which suggests other than anthropogenic causes for changing erosion regimes these may be climatic factors because changes between millennium scale phases of erosion activity coincide with pronounced climatic changes the subboreal subatlantic transition and the start of the medieval warm period however a direct correlation between erosion activity and climatic parameters warmer cooler wetter drier has not been found presumably because the available palaeoclimatic reconstructions do not contain enough information on changing frequencies and magnitudes of hydrological extremes according to population dynamics charcoal frequency in erosion derived sediments and pollen data a human impact on erosion is suggested to have occurred from the 11th century ad and more confidently from the 14th 16th centuries this contributed to erosion acceleration that began some two centuries earlier apparently for climatic reasons

atmospheric radiocarbon calibration to 45 000 yr b p late glacial fluctuations and cosmogenic isotope production more than 250 carbon 14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from lake suigetsu japan provide a first atmospheric calibration for almost the total range of the radiocarbon method 45 000 years before the present the results confirm the recently revised floating german pine chronology and are consistent with data from european and marine varved sediments and combined uranium thorium and carbon 14 dating of corals up to the last glacial maximum the data during the glacial show large fluctuations in the atmospheric carbon 14 content related to changes in global environment and in cosmogenic isotope production

geomorphometric assessment of spatial sediment connectivity in small alpine catchments abstract complex and rugged topography induces large variations in erosion and sediment delivery in the headwaters of alpine catchments an effective connection of hillslopes with the channel network results in highly efficient sediment transfer processes such as debris flows in contrast morphological conditions producing decoupling of hillslopes from channels e g glacial cirques may exclude large areas of the catchment from sediment delivery to its lower parts moreover an efficient connection between hillslopes and channel network does not always ensure an effective downstream transfer of sediment low slope channel reaches e g in hanging valleys cause sediment deposition which often results in changes of the sediment transport processes typically from debris flow to streamflow with low bedload and suspended load rates the availability of high resolution digital terrain models such as those derived from aerial lidar improves our capability to quantify the topographic controls on sediment connectivity a geomorphometric index based on the approach by borselli et al 2008 was developed and applied to assess spatial sediment connectivity in two small catchments of the italian alps featuring contrasting morphological characteristics the results of the geomorphometric analysis were checked against field evidences showing good performance and thus potential usefulness of the index

effects of bedrock landslides on cosmogenically determined erosion rates abstract the successful quantification of long term erosion rates underpins our understanding of landscape formation the topographic evolution of mountain ranges and the mass balance within active orogens the measurement of in situ produced cosmogenic radionuclides crns in fluvial and alluvial sediments is perhaps the method with the greatest ability to provide such long term erosion rates although deep seated bedrock landsliding is an important erosional process in active orogens its effect on crn derived erosion rates is largely unquantified we present a numerical simulation of cosmogenic nuclide production and distribution in landslide dominated catchments to address the effect of bedrock landsliding on erosion rates results of the simulation indicate that the temporal stability of erosion rates determined from crn concentrations in sediment decreases with increased ratios of landsliding to bedrock weathering rates within a given catchment area and that as the frequency of landsliding increases larger catchment areas must be sampled in order to accurately evaluate long term erosion rates in addition results of this simulation suggest that sediment sampling for crns is the appropriate method for determining long term erosion rates in regions dominated by mass wasting processes whereas bedrock surface sampling for crns may generally underestimate long term erosion rates response times of crn concentrations to changes in erosion rate indicate that climatically driven cycles of erosion may be detected but that complete equilibration of crn concentrations to new erosional conditions may take tens of thousands of years comparison of simulated crn derived erosion rates with a new data set of such rates from the nepalese himalaya underscore the conclusions drawn from the model results

classification and mapping of anthropogenic landforms on cultivated hillslopes using dems and soil thickness data example from the sw parisian basin france this study focuses on linear anthropogenic landforms of decametric width on cultivated hillslopes and their relations to soil thickness variability the 16 ha study area shows a rolling topography supported by cretaceous chalk of the sw parisian basin france two types of landforms were identified lynchets similar to those described as soil terraces occurring on downslope field parts in other contexts and undulations linear convex landforms that cut across fields accurate dem construction and a detailed soil thickness survey were performed all over the study area soil samples were classified considering their location on specific types of anthropogenic landforms the classification tree ct method was applied to assess whether lynchets and undulations can be discriminated through morphometric attributes slope curvature profile curvature and planform curvature and soil thickness ctsoil or through morphometric attributes only cttopo the ct application establishes predictive classification models to map the spatial distribution of lynchets and undulations over the whole study area the validation results of the ctsoil and cttopo applications show model efficiencies of 83 and 67 respectively both models performed well for lynchets errors arise mainly from difficulties in unequivocally discriminating gently convex undulations and undifferentiated surfaces especially when soil thickness is not accounted for mean values of soil thickness are 1 08 0 62 and 0 45 m in lynchets undulations and undifferentiated areas respectively the general shape of the thickened soil is characteristic to each type of anthropogenic landform multi temporal mapping of field border networks shows that undulations are linked to borders that were removed during the latest land consolidation lynchets are associated with current field borders lynchets and undulations which cover 39 of the study area define topographic indicators of human induced soil accumulations the method involves perspectives for efficiently mapping and quantifying the anthropogenically modified spatial variability of soil thickness on agricultural hillsides

sediment yield and erosion rate estimation in the mountain catchments of the camastra artificial reservoir southern italy a comparison between different empirical methods abstract the sedimentary budget assessment is an important topic for the scientific and social community because it is crucial to understand the dynamics of orogenic belts and cope with a number of practical problems such as soil conservation and sediment accumulation in reservoir sediment yield or denudation rate estimates in southern central italy are generally obtained either by applying simple empirical relationships based on the statistical regression between the geomorphic parameters of the drainage network and the suspended sediment yield measured at the drainage basins outlets or by using qualitative quantitative sediment delivery ratio or erosion models in this work we carry out a study of catchment dynamics and a sedimentary yield computation of several mountain catchments of the central western sector of the basilicata region southern italy which are located upstream of an artificial reservoir the sediment yield and erosion rate have been computed through both an indirect assessment of the suspended sediment yield based on the tu index mean annual suspension sediment yield and the application of the rusle and usped empirical methods the results obtained have been compared with the historical data of sediment accumulation measured in the artificial reservoir of the camastra dam where a detailed evaluation of the volumes of historical i e about 40 years sediment storage was collected the collected dataset represents a basic tool both for the investigation of the morpho dynamics of a typical mountain catchment of the mediterranean area and the evaluation of sediment budget related to fluvial and hillslope processes the 38 year long record of the sediment storage in the camastra artificial reservoir located at the outlet of the studied mountain catchments permits the validation of empirical relationships based on the geomorphic and climatic parameters of the drainage basin among the three different methods of sediment yield evaluation tu index rusle and usped the tu index showed the best prediction ability although usped erosion model also furnished a good estimation as also confirmed by other works the indirect estimation of sediment yield based on ciccacci s empirical relationships can represent a good proxy of short term denudation rates in the mediterranean areas with geological and geomorphological features similar to the study area but the use of empirical models with increasing complexity such as the usped erosion model can help to explore the spatial distribution of the sediment yield sectors of the drainage basin the erosion hot spots and the role of landslides in sediment mobilization and hillslope channel connectivity processes

the control mechanisms of erosion and weathering at basin scale from cosmogenic nuclides in river sediment the study of a sample of river sediment enables the determination of spatially averaged denudation rates that provide an exceptional perspective on erosion and weathering processes that have taken place within a landscape these measurements are done with in situ produced cosmogenic nuclides e g 10be 26al mostly in quartz from alluvial sediment cosmogenic nuclides are produced when secondary cosmic rays interact with the very uppermost layer of the earth s surface they are produced within a characteristic depth scale of about 1 m which means that the measured concentrations record an integrated denudation history while material passed through this depth interval depending on the denudation rate the resulting integration time scales are 103 to 105 years and one obtains a robust long term estimate of natural denudation that is relatively insensitive to short term changes the last 10 years have seen significant research activity using these methods and an array of fascinating tectono geomorphologic and geochemical insights are emerging amongst these is the ability to identify the physical and chemical processes with which a landscape responds to tectonic activity or climate change a compilation of world wide denudation rates in non glaciated areas that however does not yet include some of the world s most active mountain belts has resulted in the following findings some of which have been unexpected 1 no obvious relationship between precipitation or mean annual temperature and total denudation is apparent 2 topographic relief alone does not result in high rates of denudation 3 denudation rates are high in areas of landscape rejuvenation that is triggered and controlled by tectonic activity faulting escarpment formation and retreat rifting surface uplift 4 rates of weathering using a combination of cosmogenic nuclides and zirconium normalised cation loss balances co vary primarily with physical erosion rates and much less with temperature or precipitation 5 in some areas of high land use short term rates from river load gauging exceed those from cosmogenic nuclides by several orders of magnitude which serves to highlight the severity of geomorphic change caused by human action in the future the control mechanisms over denudation will be determined on all spatial scales ranging from the single soil section to entire river basins the same analysis can be done back through time on well dated terraces lake records and marine sediment cores which is possible with 10be for the past 1 2 my the rates obtained will be used to develop a quantitative understanding of tectonic geomorphologic and geochemical landscape processes which in turn is a prerequisite to design and calibrate models of the response of landscapes to tectonic climate and anthropogenic forcing

morphological control on sedimentation rates and patterns of delta floodplains in the swiss alps abstract glacially overdeepened alpine valleys and their perialpine lakes are very effective sedimentary sinks that include landforms as alluvial fans fan deltas and deltas the sedimentary archives of these landforms can provide long sedimentary records of erosion and aggradation processes in a catchment focusing on longer time series is vital to improve the conventional instrument based models of sediment transfer as longer time series record the effective low frequency sediment discharges triggered by high magnitude floods the research reported here combines statigraphical analysis of the sedimentary records of two lake deltas in the bernese alps with geostatistical modeling of the sedimentation storage of delta plain deposits from the three dimensional sediment storage model the sedimentary environments and aggradation dynamics of the aare and the lutschine rivers were reconstructed in 500 year time slices over the last 2500 years the spatial distributions of the aggradation rates of the two deltas show similar trends with decreasing downstream rates from delta apex to the delta front at lake brienz which is related to the adaption of the river s longitudinal profile to the pleistocene overdeepened valley morphology local modification of this trend was detected at narrowing of the valley floor caused by landslides the quantification of delta plain sediment volumes provides evidence that aggradation processes have decreased aare or remained nearly stable lutschine in the delta plains during the last 1500 years despite the strong human impact in the form of land use this decrease and the possible compensation of major human induced catchment erosion may be attributed to a more or less efficient regulation of the river channels during the last millennium which transferred the sediment load into lake brienz the sediment volumes obtained and the historical progradation of delta lobes support the previous hypothesis of the connectivity from source headwater catchments to sink perialpine lakes in the main valleys of the bernese alps the results of our study provide new insight into the quantitative estimation of sediment storage for geomorphic process modeling and into the evolution of alpine deltas during the late holocene

microbially mediated carbonates in the holocene deposits from sarlieve a small ancient lake of the french massif central testify to the evolution of a restricted environment both the mineralogy and facies of lacustrine bio induced carbonates are controlled largely by hydrological factors that are highly dependent upon climatic influence as such they are useful tools in characterizing ancient lake environments in this way the study of the sedimentary record from the small ancient sarlieve lake limagne massif central france aims to reconstruct the hydrological evolution during the holocene using petrographical mineralogical and geochemical analyses the fine grained marls mainly calcitic display numerous layers rich in pristine ca dolomite with small amounts of aragonite which are clearly autochthonous as these minerals are rather unusual in the temperate climatic context of western europe the question arises about their forming conditions and therefore that of the lacustrine environment ca dolomite prevails at the base of the sequence as a massive dolomicrite layer and in the middle part it builds up most of the numerous laminae closely associated with organic matter scanning electron microscope observations reveal the abundance of tiny crystals tens to hundreds of nanometres mainly organized as microspheres looking like cocci or bacilli such a facies is interpreted as resulting from the fossilization of benthic microbial communities by dolomite precipitation following organic matter consumption and extracellular polymeric substance degradation these microbial dolomites were precipitated in a saline environment as a consequence of excess evaporation from the system as is also suggested by their positive 18o values the facies sequence expresses the following evolution i saline pan i e endorheic stage with a perennial lowstand in lake level boreal to early atlantic periods ii large fluctuations in lake level with sporadic freshening of the system atlantic iii open lake stage sub boreal and iv anthropogenic drainage sub atlantic

sediment un balance budget in a high gradient stream on flysch bedrock a case study using dendrogeomorphic methods and bedload transport simulation abstract detailed quantification of material supply into stream channels is crucial for determining sediment un balance budget during flood events unfortunately existing quantification methods require long term field monitoring otherwise there is an insufficient amount of usable data in this study we introduce a new approach based on dendrogeomorphic methods to determine the volume of material supply generated from flysch high gradient stream bank failures this approach was supplemented by 1d sediment transport modelling using a tomsed model we analysed 138 cross sections from the roots of predominantly broad leaved trees which were exposed in bank failures from different floods using the spatial position of the roots and dating the exposure time we determined the volume of material supply into the channel during the last flood in 2010 in channel sediment transport was analysed on 14 cross sections and the channel sediment thickness was estimated using the geophysically based ert electrical resistivity tomography method the total volume of material loss during the 2010 flood within the study area according to the tomsed model was found to be at least 300 m3 this means that the calculated total volume of sediment supply resulting from bank failures during the flood 63 9 m3 based on dendrogeomorphic methods was significantly lower than the calculated bedload transport for the entire study area this finding implies that contemporary sediment sources cannot adequately cover the transport capacity during high magnitude flood events and in general in channel erosion processes prevail

extending the radiocarbon calibration beyond 26 000 years before present using fossil corals fossil coral is an excellent archive to extend the radiocarbon 14c calibration beyond tree ring records however published coral data older than 26 000 years before present are too disparate for practical calibration we propose an explanation for these discrepancies trace amounts of secondary calcite and organic matter in fossil corals shift the 14c ages toward younger ages in a series of acid leaching experiments to simulate the standard cleaning procedure prior to 14c analysis we measure up to a 300 enrichment of diagenetic calcite in corals due to the solubility differences between calcite and aragonite in model calculations we show the 14c age offsets produced by acid leaching could be hundreds to thousands of years when typical amounts of calcite are present in samples we demonstrate the necessity and our ability to detect 0 2 calcite in aragonite by x ray diffraction and apply 0 2 calcite as our a priori criterion for our coral samples the estimated age offsets of samples with 0 2 calcite fall within the reported analytical uncertainty of 14c dating in addition we present 14c results from an extended hydrogen peroxide h2o2 pretreatment for coral samples to remove organic matter our data show that treated samples yield consistent or older 14c dates compared to non treated samples these rigorous but necessary screening and cleaning techniques provide precise reproducible and accurate radiocarbon calibration data

mid to late holocene flood frequency changes in the northeastern alps as recorded in varved sediments of lake mondsee upper austria abstract annually laminated varved lake sediments with intercalated detrital layers resulting from sedimentary input by runoff events are ideal archives to establish precisely dated records of past extreme runoff events in this study the mid to late holocene varved sediments of lake mondsee upper austria were analysed by combining sedimentological geophysical and geochemical methods this approach allows to distinguish two types of detrital layers related to different types of extreme runoff events floods and debris flows and to detect changes in flood activity during the last 7100 years in total 271 flood and 47 debris flow layers deposited during spring and summer were identified which cluster in 18 main flood episodes fe 1 18 with durations of 30 50 years each these main flood periods occurred during the neolithic 7100 7050 vyr bp and 6470 4450 vyr bp the late bronze age and the early iron age 3300 3250 and 2800 2750 vyr bp the late iron age 2050 2000 vyr bp throughout the dark ages cold period 1500 1200 vyr bp and at the end of the medieval warm period and the little ice age 810 430 vyr bp summer flood episodes in lake mondsee are generally more abundant during the last 1500 years often coinciding with major advances of alpine glaciers prior to 1500 vyr bp spring summer floods and debris flows are generally less frequent indicating a lower number of intense rainfall events that triggered erosion in comparison with the increase of late holocene flood activity in western and northwestern nw europe commencing already as early as 2800 yr bp the hydro meteorological shift in the lake mondsee region occurred much later these time lags in the onset of increased hydrological activity might be either due to regional differences in atmospheric circulation pattern or to the sensitivity of the individual flood archives the lake mondsee sediments represent the first precisely dated and several millennia long summer flood record for the northeastern ne alps a key region at the climatic boundary of atlantic mediterranean and east european air masses aiding a better understanding of regional and seasonal peculiarities of flood occurrence under changing climate conditions

holocene environmental change and its impact on sediment dynamics in the eastern mediterranean abstract investigators have studied past environmental change in the eastern mediterranean region from a number of perspectives while climate reconstructions and palynological research have focused on forces that drive the geomorphologic system many researchers have attempted to use sediment archive studies to identify periods of change in sediment dynamics due to the large variability in environmental parameters and the variety of landscapes present in the eastern mediterranean region research has focused on sediment archives ranging from small colluvial sites to deltas of large rivers on the mediterranean coast as the cultural record for the region is extremely rich the main goal of palaeo environmental research in the eastern mediterranean has been to identify the relative importance of human impact on the landscape nevertheless sediment archives have significant limitations chronological control for many palaeo environmental records is highly uncertain and rates of landscape change are oftentimes difficult to assess most palaeo environmental research has been conducted on or near archeological sites where direct human impact may obscure the indirect impact on sediment dynamics through land use changes quantification and modeling of sediment dynamics in the eastern mediterranean environment offer one solution when erosion and sediment transport rate analyses are incorporated periods of relatively important change can be identified using multiple approaches the relative importance of the main driving forces climate and land use become distinguishable since field based data from the actual sediment archives remain vital an overview of numerous studies in the eastern mediterranean is provided in order to draw a general picture for different time periods and the relative scale of regional landscape development during the holocene a comparison of sediment dynamics with the record of driving forces indicates that while climate was the main driver of the geomorphic system during the early holocene at some point human impact became widespread and began to dictate sediment dynamics to a large extent from the byzantine period onward soil properties seem to play an increasingly important role as the hillslope soil reservoir in the eastern mediterranean was progressively depleted during the late holocene

limits to quantifying climate driven changes in denudation rates with cosmogenic radionuclides abstract the hypothesis that climate change significantly modifies the denudation history of an orogen can be tested by reconstructing catchment wide denudation histories cosmogenic radionuclides measured in sediment deposits of known age e g a sequence of fluvial terraces offer one approach for quantifying catchment wide paleo denudation rates we present a numerical model and two case studies that evaluate the utility of this technique for reconstructing different denudation histories the concentration of cosmogenic beryllium 10 10 be is calculated for a sequence of sediments produced from climate driven variations in the mean denudation rate of a drainage basin at sea level and high latitude the model accounts for the nucleonic and muonic production and decay of 10 be as sediment is eroded and stored in deposits of different ages two scenarios for different climate driven denudation histories are considered 1 a sinusoidal variation in the input denudation rate with free parameters of periodicity 23 41 100 kyr amplitude 0 1 0 5 1 0 and mean denudation rate 0 01 0 1 1 0 mm yr 1 2 a climate driven denudation history based on oscillations of a global benthic foraminiferal oxygen isotope 18 o record over the last 2 myr results from both scenarios suggest cosmogenic radionuclides measured in a system with high denudation rates 0 5 mm yr 1 longer periodicity 100 kyr and low amplitude have the highest potential for reconstructing climate driven paleo denudation rates unfortunately the high denudation rates preferred in the theoretical consideration are not suitable for paleo denudation rate determination due to overprinting of nuclides accumulated during denudation by post depositional decay and irradiation hence a compromise between the capability to determine changes in paleo denudation rates and the determination of true denudation rates has to be accepted application of the model to previous data sets from northwest europe and southwest north america produce a good agreement but highlight the need for future work to consider how geomorphic processes e g landsliding respond to climate change and influence catchment wide denudation rates in addition other climate proxies than the benthic foraminiferal 18 o record should be used for specific sample locations

quantifying fluvial non linearity and finding self organized criticality insights from simulations of river basin evolution abstract a numerical study was undertaken to investigate non linearity and the potential for self organized criticality soc in the evolution of river basins twenty three simulations were carried out using the authors caesar landscape evolution model in which the magnitude of storm events variability of storm events sediment heterogeneity sources of sediment supply and catchment morphology are systematically varied to evaluate their importance as possible drivers for non linear behavior and soc temporal fluctuations in simulated sediment yield show notable non linear behavior storm magnitude and occurrence of landslides appear to have little impact on variability of the sediment yield when compared to the impacts of sediment heterogeneity rainfall variability and catchment morphology particularly it appears that the non linearity of sediment yields results from the manner in which the catchment processes the variable rainfall rather than just the rainfall variability itself the variations in sediment yield show a power law magnitude frequency distribution which is a possible but inconclusive indicator of soc however several other more qualitative arguments can be made to support the case for soc in these simulations specifically we identify the nature of the critical state and suggest two cascade mechanisms by which the system can organize itself around this critical state combined these arguments indicate that simulated evolution of river basins indeed exhibits soc at least with respect to sediment yield the critical state appears to be an indicator of the connectivity of the drainage network thus the simulations indicate that unlike traditional soc systems the critical state of the system can vary in time as sudden changes in drainage network connectivity may result in sudden changes in the soc behavior of the system

holocene river and slope activity in the visoko basin bosnia herzegovina climate and land use effects alluvial and colluvial deposits were investigated at prehistoric tells close to the bosna river the chronology is based on ten radiocarbon ages five optically stimulated luminescence ages and on the archaeological record fluvial activity of the bosna river is indicated by overbank fines ca 5000 1000 bc 500 bc until today and a phase of lateral displacement of the river bed with subsequent channel fills ca 2000 500 bc early holocene fluvial activity was probably triggered by climatic variability but might have promoted the expansion of neolithic societies into the visoko basin mid to late holocene river activity occurred under increased climatic aridity but coincided with the expansion of prehistoric settlements to a wider area of the river basin on hard rocks in the adjacent mountainous areas the destruction of the thin soil cover in the mountains is discussed as a probable trigger for enduring subsequent river activity this is also indicated by a change in the geochemical signature of the alluvial sediments the proposed mechanism might explain the mid to late holocene river history in other regions the potential of geochemical analyses and diachronous high resolution archaeological records to make inferences regarding sediment sources and geomorphological processes is demonstrated copyright 2013 john wiley sons ltd

robust chronologies for landform development obtaining chronological control for geomorphological sequences can be problematic due to the fragmentary and non sequential nature of sediment and landform archives the robust analysis of 14c ages is often critical for the interpretation of these complicated sequences this paper demonstrates a robust methodology for the 14c dating of geomorphological sequences using a case study from the lower ribble valley northwest england the approach adopted incorporates using greater numbers of ages targeting plant macrofossils obtaining replicate measurements from single horizons to assess the extent of reworking and the use of bayesian approaches to test models of the relative order of events the extent of reworking of organic materials and space time dynamics of fluvial change means that it is critical that chronological control is sufficiently resourced with 14c measurements as a result bayesian approaches are increasingly important for the evaluation of large data sets assessing the conformability of relative order models informed by interpretation of the geomorphology can identify contexts or materials that are out of sequence and focuses attention on problem materials reworking and errors in interpretation outlier ages these relative order models provide a framework for the interrogation of sequences and a means for securing probability based age estimates for events that occur between dated contexts this approach has potential value in constraining the sequence of geomorphological development at scales that vary from individual sites to a catchment or region furthering understanding of forcing and change in geomorphological systems copyright 2008 john wiley sons ltd

combining ground penetrating radar surveys and optical dating to determine dune migration in namibia ground penetrating radar gpr profiles across a complex linear dune in the namib sand sea have been used to image sets of cross stratification and their bounding surfaces a combination of radar facies analysis and radar stratigraphy has been used to interpret the radar profiles and define a relative chronology thick sets of cross stratification indicate when the dune was most active whereas thin sets of cross stratification are interpreted to indicate the increased prevalence of wind reversals and lower rates of dune migration with bounding surfaces formed during periods of stabilization non deposition or erosion a drilling and dating campaign was designed on the basis of the dune stratigraphy as defined by the gpr survey sampling was targeted at large sets of cross stratification formed when the dunes were most active and avoiding bounding surfaces formed when the dune was stable or even eroded the results from optical dating give ages between 0 34 0 02 ka and 1 57 0 07 ka indicating a time averaged dune migration rate of 0 12 m a 1 over the past 1600 years

from gullies to mountain belts a review of sediment budgets at various scales this paper reviews the state of the art in the concept as well as in the application of sediment budgets in sedimentary research sediments are a product of mass dispersal at the earth surface and take part in global cycles sediment budgets aim at quantifying this mass transfer based on the principle of mass conservation and are the key to determine ancient fluxes of solid matter at the earth surface this involves fundamental questions about the interplay of uplift climate and denudation in mountain belts and transfer of sediments from the continents to the oceans as well as applied issues such as soil and gully erosion reservoir siltation and coastal protection first after introducing basic concepts relevant scales and methodologies the different components of quaternary routing systems from erosion in headwaters river systems glacial and paraglacial systems lakes deltas estuaries coasts shelves epicontinental seas and deep sea fans are discussed in terms of their sediment budget most suitable are sedimentologically closed or semi closed depositional environments e g alluvial fans lakes deltas and deep sea fans in a second step the dynamics of passive active and collisional tectonic settings and sediment budgets in related sedimentary basins are explored and new concepts of sediment portioning at large geodynamic scales are introduced ancient routing systems are more or less incomplete and may be intensively fragmented or destroyed in active tectonic settings in terms of sedimentary basin types rifts intracontinental and epicontinental settings are preferred objects of sediment budgets because of their persistence and relatively simple overall sedimentary architecture however closing basins such as foreland forearc retroarc piggy back and wedge top basins may provide excellent snapshots of orogenic sediment fluxes in a third step the large long lived routing systems of the amazon the ganges brahmaputra and the rhine are reviewed for each system estimates of either sediment volumes mass or sediment fluxes of continental and marine subsystems have been compiled in order to receive a complete routing in terms of mass conservation for specific time periods since the late glacial maximum as well as the cenozoic following lessons can be taken from these case studies i depositional centers and fluxes show strong shifts in space and time and call for caution when simply looking at subsystems ii the response times of these large systems are within the milankovich time interval thus lower than predicted from diffusion models iii cyclic routing of sediments in continental basins is much more dominated by climate human control than by eustacy and iv at long time scales ultimate sinks win over intermittent storage it is concluded from this review that the quantitative understanding of global sediment cycling over historic and geologic time and its response to allogenic forcing is still in its infancy and further research is needed towards a holistic view of sediment routing systems at various temporal and spatial scales and their coupling with global biogeochemical cycles this includes i to better determine response times of large routing systems by linking quaternary with cenozoic sediment budgets and continental with marine sub systems ii to combine advanced provenance techniques with sediment budgets in order to reconstruct ancient systems iii to study sediment partitioning at the basin scale iv to reconcile continental supply dominated sequence stratigraphy with the eustatic dominated marine concept and iv to account for non actualism of ancient systems with respect to their erosion and transport mode in particular during glaciations and pronounced arid intervals glacial and eolian sediment routing may cross over hydrologic boundaries of drainage basins thus challenging the principle of mass conservation

holocene floodplain sediment storage and hillslope erosion within the rhine catchment the response of fluvial systems to land use and climate change varies depending on catchment size while forcing response mechanisms of small catchments are reasonably well understood the response of larger drainage basins is less clear in particular the impact of land use and climate change on the rhine system is poorly understood because of the catchment size 185 000 km 2 and the long history of human cultivation which started approximately 7500 years ago a sediment budget is calculated to specify the amount of alluvial sediment that was deposited during the holocene and to estimate long term soil erosion rates the results suggest that 599 14 10 9 t of holocene alluvial sediment is stored in the non alpine part of the rhine catchment south and central germany eastern france the netherlands about 50 of holocene alluvial sediment is deposited along the trunk valley and the delta upper rhine lower rhine coastal plain while the rest is stored along the tributary valleys the floodplain sediment storage corresponds to a mean erosion rate of 0 559 0 16 t ha per yr 38 59 10 7 mm kyr across the rhine catchment outside the alps this holocene averaged estimate amounts for sediments that were delivered to the channel network and is at the lower limit of erosion rates from other studies of different methodology

a new technique for precise uranium series dating of travertine micro samples abstract secondary carbonate formations such as travertine and calcareous tufa deposits are important archives for quaternary continental climate studies and archaeology the extremely complex growth mechanisms result in some serious problems for precise mass spectrometric uranium series dating often detrital and organic particles contaminate the carbonate and large pore volumes yield a great potential for open system behavior we utilized microscopic mineralogical and geochemical methods prior to sample selection to determine the abundance of primary calcite i e micrite and spar furthermore the state of alteration was characterized by cathodoluminescence and trace element analysis we conclude that travertine and calcareous tufa are appropriate for precise u series age determination if a micrite and or spar are the dominant phases b cathodoluminescence of both phases is weak or absent c fe and al levels are low and d sr concentrations are close to the average of the studied site we mapped and sampled solely areas of major micrite spar abundance having minor alteration for accurate u series dating when this new method was applied travertines located in eastern germany sites bad langensalza burgtonna and weimar ehringsdorf gave single 230th 238u ages consistent with the lithological growth sequence and greatly improved compared to previously published chronologies in addition we determined 230th u isochron ages on bulk samples that confirm our single ages in contrast to primary calcite pore cements are homogeneously distributed throughout the travertine fabric and reflect early diagenetic processes and or weathering

geoarchaeology the four dimensional 4d fluvial matrix and climatic causality abstract geoarchaeology is the application of geological and geomorphological techniques to archaeology and the study of the interactions of hominins with the natural environment at a variety of temporal and spatial scales geoarchaeology in the uk over the last twenty years has flourished largely because it has gone beyond technological and scientific applications over the same period our ability to reconstruct the 3 dimensional stratigraphy of fluvial deposits and the matrix of fluvial sites has increased dramatically because of a number of technological advances these have included the use of lidar laser imaging and radar to produce high resolution digital surface models the use of geophysics particularly ground penetrating radar and electrical resistivity to produce sediment depth models and the use of gis and data visualisation techniques to manipulate and display the data these techniques along with more systematic and detailed sedimentological recording of exposed sections have allowed the construction of more precise 3 dimensional volumetric models of the matrix of artefacts within fluvial deposits additionally a revolution in dating techniques particularly direct sediment dating by luminescence methods has enabled the creation of 4 dimensional models of the creation and preservation of these sites these 4 dimensional models have the ability to provide far more information about the processes of site creation preservation and even destruction and also allow the integration of these processes with independent data sources concerning cultural evolution and climatic change all improvements in the precision of dating fluvial deposits have archaeological importance in our need to translate events from a sequential or geological timeframe to human timescales this allows geoarchaeology to make a more direct contribution to cultural history through the recognition of agency at the individual or group level this data can then form a component of biocomplexity or agent based modelling which is becoming increasingly used in the natural sciences particularly ecology and geomorphology and which can be used to test scenarios including the impact on and response of hominins to abrupt or catastrophic environmental change whilst catastrophic events clearly represent the atypical they can be illuminating in revealing cognitive processes resulting in abandonment coping mitigation and innovation these points are exemplified using two in depth case studies one from the holocene geoarchaeological record of the river trent in central england and the other from the palaeolithic record from rivers in south west britain in the former the interaction between climate change and human activity is illustrated at the year to century timescale whilst in the other the timescale is millennial these case studies have deliberately been chosen to be as different as possible in temporal and spatial scale with the aim of examining the applicability of methodological and theoretical aspects of geoarchaeology lastly the paper considers the problem of scale in geoarchaeology and concludes it is process dependency which ultimately affects the questions we can ask and that questions of human response to climate change are fundamentally a product of materiality and cognitive processes this demands an in depth contextual approach to such questions rather than database driven assertions of causality

advances in holocene mountain geomorphology inspired by sediment budget methodology the sediment budget which links sediment sources to sediment sinks with hydroclimatic and weathering processes mediating the response is applied to the analysis of sediments in three alpine lakes in british columbia we provide two ways of using the sediment budget as an integrating device in the interpretation of mountain geomorphology these approaches differ in their resolution and ability to budget the major components of the fine sediment cascade in glaciated environments taken together they provide an integrated index of landscape change over the holocene the first example compares the hydroclimatic controls of lake sedimentation for the last 600 years a d 1370 1998 preserved in varved sediments from two of the lake basins this hydroclimatological approach incorporates contemporary monitoring air photo analysis and detailed stratigraphy of sedimentation events within a single varve to infer the timing sources and preferred pathways of fine grained sediments reaching the lake basins the results indicate that glaciers hillslope and channel instability within the major subbasins are the principal sediment sources to the lake basins transitory sediment storage of glacially derived sediments within the channels is believed to modulate the episodic and more frequent delivery of sediments from adjacent hillslope and fluvial storage sites and direct routing of glacial rock flour during years of prolonged glacial melt the second example relying on the phosphorus geochemistry of sediments in an alpine lake basin considers the evolution of phosphorus forms from mineral to occluded and organic fractions as a function of the soil development inherent slope instability and repeated cycles of glaciation and neoglaciation over the holocene this geochemical approach demonstrates that both neoglaciation and full glaciation have essentially zeroed the system in such a way that a high proportion of mineral phosphorus remains in the present lake sediments and the bioavailability of phosphorus a key to ecosystem development is low both examples illustrate the importance of variable sediment sources the seasonality frequency and magnitude of sediment transfers and the profound influence of ice cover over contemporary neoglacial and pleistocene time scales they also signal the value of including both clastic and dissolved components in the sediment budget d 2003 elsevier science b v all rights reserved

the development and application of a database of radiocarbon dated holocene fluvial deposits in great britain abstract this paper reports on the development of a british database of 14c dated holocene fluvial units over the last 15 years since its inception in 1989 the database has undergone substantial expansion refinement and improvement together with considerable methodological development so that today it serves as a powerful research tool for investigating the spatial and temporal dynamics of holocene river development and flooding in great britain the improved analytical method is here applied to the currently existing database by examining datasets of 14c dated fluvial units from river basins that lie within and beyond the limits of late devensian glaciation this analysis indicates how the contrasted conditions in these two types of river environment have to an extent led to divergent records of flooding in response to holocene climate and land use change however even in the contrasting sedimentary records of upland glaciated and lowland unglaciated river basins six corresponding episodes of increased flood frequency are identified at c 5730 c 3540 c 2730 c 2280 c 660 and c 570 cal bp these represent widespread common responses from british river systems to large scale changes in climate the method of database construction and analysis outlined and demonstrated in this paper could be readily adopted in other parts of the world to improve our understanding of holocene river behaviour at the continental and global scale

late pleistocene holocene river dynamics at the trent soar confluence england uk although river confluences have received geomorphic attention in recent years it is difficult to upscale these studies so confluence dominated reaches are commonly presumed to be either 1 braided or 2 meandering and characterized by laterally migrating channels if the geomorphology of a confluence zone is to be considered over longer timescales changes in river style need to be taken into account this paper uses a combination of remote sensing techniques lidar gpr er borehole survey and chronometric dating to test this differentiation in the confluence zone of a medium sized mixed load temperate river system trent uk which on the basis of planform evidence appears to conform to the meandering model however the analysis of confluence sediment body stratigraphy demonstrates that the confluence does not correspond with a simple meander migration model and chronostratigraphic data suggests it has undergone two major transformations firstly from a high energy braid plain confluence in the lateglacial 25 13 k yrs cal bp to a lower energy braided confluence in the early to middle holocene early holocene 2 4 kyr bp which created a compound terrace second incision into this terrace creating a single channel confluence 2 4 0 5 kyr cal bp with a high sinuosity south bank tributary the river soar the confluence sediment body stratigraphy is characterized by a basal suite of late pleistocene gravels bisected by younger channel fills which grade into the intervening levee and overbank sediments the best explanation for the confluence sediment body stratigraphy encountered is that frequent switching soft avulsions sensu edmonds et al 2011 of the tributary are responsible for the downstream movement of the channel confluence at an average rate of approximately 0 5 m per year dissecting and reworking older braid plain sediments the late holocene evolution of the confluence can be seen as a variant of the incisional frequent channel reorganization avulsion model with sequential downstream migration of the reattachment point copyright 2012 john wiley sons ltd

quantification and regulation of organic and mineral sedimentation in a late holocene floodplain as a result of climatic and human impacts taligny marsh parisian basin france quantification in grams per metres squared per year of the sediment accumulation in a flood plain marsh located in the southwestern parisian basin showed that there is no close relationship between the accumulation of organic matter om and mineral matter mm during the late holocene and provided an accurate view of the distinct yield and storage conditions of both sediment components endogenic om accumulation in peaty sediments is not related to the climate but to felling of the alder forest and its substitution by cyperaceae and paludal taxa in the marsh iron age and middle ages mm accumulation expresses mainly the sediment yield on the slopes determined by landuse during an initial phase from the late neolithic to the early middle ages land use change from crop cultivation to pastureland possibly related to climate deterioration led to a decrease in the sediment yield during a second phase since the early middle ages the considerable development of crop cultivation over pasturing even during periods of climate deterioration such as the little ice age led to a sharp increase in sediment yield however although sediment yield was high the hydrodynamics in the fen did not favour particle retention thus since the neolithic yield and storage of om and mm sediment have been marked by human activities initially with high climatic stress but since the middle ages without significant climatic stress

sediment residence time and connectivity in non equilibrium and transient geomorphic systems abstract growing empirical evidence shows that many geomorphic systems are in transient state or out of equilibrium with respect to the external driving forces the transient state is often related to the dis connectivity of the many constituent parts of geomorphic systems as a result of sediment storage along the sediment flow path from its source to the final sink the response time of geomorphic systems to external changes is thus dependent on the residence time of sediment in various storage compartments here i present a mathematical concept based on reservoir theory to model residence time of sediment using millennial scale sediment budgets the framework sheds light on the limitation of the sediment delivery ratio which is often used as a measure of sediment connectivity in geomorphic systems and provides analytical information on process type pace of sediment flux and connectivity of storage compartments along the sediment cascade the application of the reservoir theory to geomorphic systems under agricultural land use shows that sediment delivery ratios are linked to the virtual velocity of the eroded sediment the time since the onset of agricultural land use and the size of the studied basins with respect to the temporal evolution of sediment storages that temporarily remove sediment from the conveyor belt the framework aims to estimate the sediment residence time in storages which is linked to the effective time scale of disconnectivity reanalysis of a long term empirical sediment budget from central europe reveals that the response to agricultural land use which started 5000 years bp is mainly buffered by the long residence time of sediment on hillslopes in the order of 10 3 years which results in a delayed floodplain aggradation furthermore the framework was applied to paraglacial mountain systems that inherit striking evidences of pleistocene glacial erosion and still recover from the change from glacial to interglacial conditions as a consequence of the reduced lateral and longitudinal connectivity i show that paraglacial response times of sediment flux in mountain headwater in the canadian rocky mountains range in the order of 100 400 ka the results indicate that response times at the transition from glacial to interglacial conditions are much longer than the return interval of the major glaciations causing a transient behavior of mountain headwater basins during interglacial periods the presented reanalysis of millennial scale sediment budgets of agricultural and mountain geosystems provides an integrative framework to link paleo environmental reconstructions and the connectivity of transient geomorphic system to external changes

late holocene environmental change in the howgill fells northwest england abstract new data from chapel beck in the southwest howgill fells combined with existing data support the identification of three phases of extensive hillslope gullying after 2200 between 1250 700 and after 500 cal bp examination of cumulative probability density function cpdf plots of the distribution of calibrated radiocarbon dates confirms the identification of these phases there are differences in the spatial distribution of geomorphic activity between these phases with the c 2200 1800 cal bp episode limited to the western howgill fells in comparison the 1250 700 and post 500 cal bp episodes are more widespread cross region phenomena and affected the more remote central fells pollen and geochemical data reveal several phases of increased human activity in these uplands with small scale temporary clearances during the late bronze age early iron age and more substantial clearances during the late iron age and romano british times 2300 1500 cal bp and these were followed by woodland expansion and decline in human activity during both the mid to late iron age and the period after the roman withdrawal from britain after 1500 cal bp the final substantial woodland clearances occurred from c 1100 900 cal bp after which there has been little woodland recovery a range of pollen sites across the howgill fells indicate that there is spatial variability in the level of human activity and impact iron age romano british woodland clearances appear to have affected the west of the region more than the remote central valleys whereas the later 1100 900 cal bp woodland reduction affected the entire region this pattern is similar to that identified from the geomorphology and demonstrates the importance of pollen sites that record local palaeo vegetation information and the significance of using a series of sites to explore intra regional variability in the vegetation history we suggest that human activity is a critical factor in mediating the late holocene geomorphic record but climate and particularly individual storms are the trigger mechanism responsible for erosion and incision on hillslopes and within the wider fluvial system palaeoclimate data humification and plant macrofossil from peat deposits at archer moss identify shifts to wetter conditions c 3100 2700 2400 1700 1300 1100 and after 650 cal bp and probably reflect increases in summer wetness of these the 2400 1700 1300 1100 and post 650 cal bp wetter phases coincide with increased geomorphic activity and perhaps encouraged incision on hillslopes rendered more susceptible to erosion by the activities of people

the influence of landscape configuration upon patterns of sediment storage in a highly connected river system abstract orthoimages are used to analyze the influence of valley width channel slope and the area of landslides that deliver sediment to valley floors upon the downstream pattern of sediment storage in the liwu basin eastern taiwan confined valley settings dominate this steep deeply dissected uplifting mountainous basin although they occupy 82 of the whole channel network sediment storage is limited in these reaches partly confined valley settings are restricted to relatively short reaches of two tributary systems over 95 of sediment storage in the liwu river is found within the short alluvial section of laterally unconfined valley close to the river mouth lateral bars are the primary features associated with sediment storage in confined reaches 54 in total volume while floodplains dominate the partly confined and laterally unconfined reaches 95 in total volume downstream patterns of sediment storage are controlled primarily by valley confinement i e valley width and landscape configuration channel slope and locations of contemporary landslides are not key determinants of sediment storage patterns sediment accumulation at confluence zones is not determined by the catchment area of tributaries or by landslide area rather it is determined by valley confinement of the trunk stream at the confluence and the associated downstream sequence of river types sediment conveyance is very effective within this highly connected river system

interpreting alluvial archives sedimentological factors in the british holocene fluvial record abstract a holocene alluvial archive of 506 dated units for great britain is analysed in terms of the sedimentation styles involved the database is classified by sedimentation unit channel sediments palaeochannel fills floodplain surface sediments floodbasins and colluvial deposits and alluvial ensemble fans and cones upland gullies and streams braided systems and active inactive meandering and anastomosing systems floodplain palaeochannel and floodbasin sediments dominate the record mostly from meandering anastomosing systems different sediment units show varied potential for recording environmental change some are relatively poorly dated with respect to the volumes of material involved whilst many dates float in periods of depositional activity which lasted for extended time periods much dated activity is autogenic and of relatively little value in interpreting external environmental influence ensembles and units are similar in age patterns in some respects commonly they exhibit sets of short term peaks in sedimentation activity but differ in others floodbasins and to an extent braided systems feature in the earlier holocene whilst dated fan deposition is more evident in the late holocene there is a general bias towards sediment units of late holocene age which probably reflects preservation factors previous british holocene alluviation models are reviewed it is suggested that the majority of earlier models reflect partial views imposed by limited regional coverage and available dating

from sedimentary records to sediment budgets multiple approaches to catchment sediment flux this paper reviews the traditional approach to sediment budget studies in geomorphology new approaches and more specifically the potential impact of new methodological advances each component of the budget is discussed including the spatial and volumetric estimations of erosion deposition and storage and the precision and accuracy of flux rate estimation examples are used from recent work in germany the netherlands and the uk and include the pedogenic approach to erosion estimation remote sensing lidar geophysics and sediment based dating techniques for flux rate estimation the precision and accuracy of catchment sediment flux estimates based upon sediment storage is not only dependant upon volumetric accuracy but also on the precision and accuracy of sediment dating in this area there has been a revolution with direct sediment dating techniques tl osl esr freeing budget studies from the constraints and biases of radiocarbon of particular importance is the use of cosmogenic nuclides for dating but which can also be used to derive long term erosion rates but only using a steady state assumption finally a tentative initial application of the sediment budget approach to pleistocene terrace staircase in unglaciated basins is discussed it is argued that only now do we have the techniques available to be able to produce accurate sediment budget estimations at spatial scales greater than that of zero order basins and over time periods greater than that covered by direct observations

establishing sediment budgets for two small lowland agricultural catchments in the uk sediment budgets have been established for two small 4 km2 lowland agricultural catchments by using 137cs measurements sediment source fingerprinting and more traditional monitoring techniques to quantify the individual components of the budget the gross and net erosion rates for the fields on the catchment slopes were estimated using 137cs measurements within selected fields which encompassed a representative range of slope angles slope lengths and land use these estimates were extrapolated over the entire catchment using a simple topographically driven soil erosion model terrain based gis tbgis superimposed on a dem to derive catchment average gross and net erosion rates suspended sediment yields were measured at the catchment outlets and sediment source fingerprinting techniques were used to establish the relative contributions from the catchment surface subsurface tile drains and eroding channel banks to the sediment yields in channel and wetland storage were quantified using both direct measurements and 137cs measurements the sediment budgets established for the catchments highlighted the importance of subsurface tile drains as a pathway for sediment transfer accounting for ca 60 and 30 of the sediment output from the two catchments erosion from channel banks contributed ca 10 and 6 of the sediment output from the two catchments although the suspended sediment yields from these catchments were considered high by uk standards ca 90 t km 2 year 1 the sediment delivery ratios ranged between 14 and 27 indicating that a major proportion of the mobilised sediment was stored within the catchments in field and field to channel storage were shown to be of similar magnitude but storage of sediment in the channel system and associated wetlands was relatively small representing 5 of the annual suspended sediment yield

large scale structure of calamus river deposits nebraska usa revealed using ground penetrating radar the large scale i e bar scale structure of channel deposits of the braided low sinuosity calamus river nebraska is described using ground penetrating radar gpr profiles combined with vibracores basal erosion surfaces are generally overlain by medium scale trough cross stratified sets 3 25 cm thick very coarse to medium sands that are associated with relatively high amplitude discontinuous gpr reflectors overlying deposits are bioturbated small scale cross stratified sets 3 cm thick and vegetation rich fine to very fine sands that are associated with low amplitude discontinuous reflectors near surface peat and turf have no associated gpr reflectors in along stream profiles through braid and point bars most gpr reflectors dip downstream at up to 2 relative to the basal erosion surface but some reflectors in the upstream parts of bars are parallel to the basal erosion surface or dip upstream in cross stream profiles through bars gpr reflectors are either approximately parallel to bar surfaces or have low angle inclinations up to 6 towards cut banks of adjacent curved channels basal erosion surfaces become deeper towards cut banks of curved channels these structures can be explained by lateral and downstream growth of bars combined with vertical accretion convex upwards forms up to 0 5 m high several metres across and tens of metres long represent episodic accretion of unit bars scroll bars and bar heads stratal patterns in channel fills record a complicated history of erosion and deposition during filling including migration of relatively small bars a revised facies model for this type of sandy braided river has been constructed based on this new information on large scale bedding structure

age and source of colluvial sediments at vaihingen enz germany abstract colluvial sediments accumulated on the lower slopes of a ridge as a result of past and present soil erosion were dated by optical 14 c and archaeological methods this allowed us to reconstruct the depositional history of the colluvium and also to identify temporary sedimentary sinks in its transportational pathway a cascade model of colluvium formation is developed colluvial sediments resulting from early soil erosion in the neolithic to iron age periods were mainly deposited on the upper slopes significant deposition on the lower slope occurred for the first time during the iron age and roman period since then deposition rates have increased because of more intensive land use

sea state dependent wind work on the oceanic general circulation 1 we examine sea state dependent wind work on the oceanic general circulation using a wave hindcast dataset quikscat winds and geostrophic and total ocean surface currents from 1 aviso and 2 ecco2 model products for wind work on surface geostrophic currents estimated from aviso or ecco2 sea state dependent wind stress increases an average of 24 0 17tw or 23 0 15tw compared with estimates that exclude sea state effects for wind work on the total surface currents the sea state dependent wind stress increases the wind work by about 24 0 4tw in terms of spatial distribution the increase in wind power input occurs mainly in high wind tropical regions and the mid latitude storm track regions like the antarctic circumpolar current region where the relatively rough ocean surface is characterized by young waves and high winds by comparison in some regions with relatively low winds and mature ocean waves there is a slight reduction in estimated wind power input

establishing fine grained sediment budgets for the pang and lambourn locar catchments uk summary an integrated approach to data collection combining the use of 137cs measurements sediment source fingerprinting bed sediment surveys and conventional river monitoring has been successfully employed to establish the fine grained sediment budgets of two lowland groundwater fed catchments in the uk gross surface erosion is higher on cultivated land pang 55 263 t yr 1 or 507 t km 2 yr 1 lambourn 79 997 t yr 1 or 437 t km 2 yr 1 than on pasture pang 1960 t yr 1 or 140 t km 2 yr 1 lambourn 1425 t yr 1 or 95 t km 2 yr 1 in both study areas and a substantial proportion of the mobilized sediment is sequestered within the fields pang 28 058 t yr 1 or 228 t km 2 yr 1 lambourn 55 575 t yr 1 or 281 t km 2 yr 1 and between the individual fields and the river channel network pang 28 672 t yr 1 or 233 t km 2 yr 1 lambourn 24 782 t yr 1 or 125 t km 2 yr 1 the sediment contribution from banks and subsurface sources is relatively low and typically ca 5 t yr 1 in the pang and ca 11 t yr 1 in the lambourn representing only about 1 of the suspended sediment output from each study catchment the mean level of fine grained sediment storage in the main channel system is equivalent to 38 pang and 21 lambourn of the respective mean annual suspended sediment yields of the two catchments the estimated sediment delivery ratio for both study catchments is ca 1

erosion and exhumation in the himalaya from cosmogenic isotope inventories of river sediments the outward erosional flux is a key factor in the tectonic evolution of mountain belts and there is much debate about the feedbacks between tectonics erosion and climate here we use cosmogenic nuclides 10be and 26al analysed in quartz from river sediments from the upper ganges catchment to make the first direct measurements of large scale erosion rates in a rapidly uplifting mountain belt the erosion rates are highest in the high himalaya at 2 7 0 3 mm yr 1 errors fall to 1 2 0 1 mm yr on the southern edge of the tibetan plateau and are 0 8 0 3 to 0 6 mm yr in the foothills to the south of the high mountains these relative estimates are corroborated by the nd isotopic mass balance of the river sediment analysis of sediment from an abandoned terrace suggests that similar erosion rates have been maintained for at least the last few thousand years the data presented here along with data recently published for european river catchments demonstrate that a log linear relationship between relief and erosion rate holds over three orders of magnitude variation in erosion rate and between very different climatic and tectonic regimes the erosion rate estimates from cosmogenic nuclides correlate well with exhumation rates calculated from previously published apatite fission track ages in the indian himalaya this confirms that much of the exhumation in the himalayan mountain chain is now balanced by erosion however exhumation rates calculated from high blocking temperature systems such as 40ar 39ar in muscovite imply lower exhumation rates rocks presently at the surface must have undergone a three to six fold increase in exhumation rate within the last few million years we show how this could be explained either by climatic forcing of erosion rate changes or by tectonics published evidence for equally rapid changes of exhumation rate in the past and the probable diachroneity in the time at which the present exhumation rates accelerated imply that tectonics has moderated at least some of the change in exhumation rates

rock to sediment slope to sea with 10be rates of landscape change abstract measurements of cosmogenic nuclides predominately 10be allow new insights into the ways in which and the rates at which sediment is generated transported and deposited over timescales ranging from 103 to 106 years samples from rock exposures are used to estimate erosion rates at points on the landscape whereas samples of fluvial sediment provide estimates of basin scale rates of denudation integrated over 104 km2 nuclide data show that hilltop bare rock outcrops erode more slowly than basins as a whole suggesting the potential for relief to increase over time as well drained outcrops grow higher more elaborate experiments and interpretive models provide insight into the distribution of hillslope processes including the bedrock to soil conversion rate which appears to increase under shallow soil cover and then decrease under deeper soils changes in average nuclide activity down slopes can be used to estimate grain speed over millennia suggesting for example that sediment o

boreal summer intraseasonal phases identified by nonlinear multivariate empirical orthogonal function based self organizing map esom analysis abstractthis study develops an empirical orthogonal function eof based self organizing map som esom analysis to identify the nonlinear characteristics of the boreal summer intraseasonal oscillation bsiso which involves interactions between the summer mean circulation and the convectively coupled equatorial waves which make bsiso evolution more complex than the madden julian oscillation the method utilizes the first five principal components of the outgoing longwave radiation olr and the zonal wind at 850 hpa u850 and has the advantages of filtering out uncertainties from noise and being free from mathematical restrictions such as orthogonality and linearity the esom analysis enables the detection of bsiso over the asian summer monsoon region with eight phases the four most distinguishable phases represent 1 a pair of stationary patterns with a dipole between the eastern indian ocean and the philippine sea phases 1 and 5 and 2 a pair of propagating patterns with a northwest southeast t

the geomorphology of the anthropocene emergence status and implications the anthropocene is proposed as a new interval of geological time in which human influence on earth and its geological record dominates over natural processes a major challenge in demarcating the anthropocene is that the balance between human influenced and natural processes varies over spatial and temporal scales owing to the inherent variability of both human activities as associated with culture and modes of development and natural drivers e g tectonic activity and sea level variation against this backdrop we consider how geomorphology might contribute towards the anthropocene debate focussing on human impact on aeolian fluvial cryospheric and coastal process domains and how evidence of this impact is preserved in landforms and sedimentary records we also consider the evidence for an explicitly anthropogenic geomorphology that includes artificial slopes and other human created landforms this provides the basis for discussing the theoretical and practical contributions that geomorphology can make to defining an anthropocene stratigraphy it is clear that the relevance of the anthropocene concept varies considerably amongst different branches of geomorphology depending on the history of human actions in different process domains for example evidence of human dominance is more widespread in fluvial and coastal records than in aeolian and cryospheric records so geomorphologically the anthropocene would inevitably comprise a highly diachronous lower boundary even to identify this lower boundary research would need to focus on the disambiguation of human effects on geomorphological and sedimentological signatures this would require robust data derived from a combination of modelling and new empirical work rather than an arbitrary war of possible boundaries associated with convenient but disputed golden spikes rather than being drawn into stratigraphical debates the primary concern of geomorphology should be with the investigation of processes and landform development so providing the underpinning science for the study of this time of critical geological transition

interpreting erosion rates from cosmogenic radionuclide concentrations measured in rapidly eroding terrain a combination of numerical analysis and 10be concentrations measured in sediment samples from the high relief torrente catchment southern spain allows us to investigate the sampling requirements for determining erosion rates using cosmogenic nuclides in high relief landslide dominated terrain we use simple modelling to quantify the effect of particle spalling and or landsliding on erosion rates determined using a cosmogenic in situ produced isotope analytical results show that the cosmogenic nuclide concentration of a surface experiencing regular detachment of a grain or block may be considered to be in steady state and in situ erosion rates estimated when an appropriate number of spatially independent samples are amalgamated we present equations that enable calculation of the number of bedrock samples that must be amalgamated for the estimation of mean erosion rates on an outcrop experiencing regular detachment of a grain or chip of thickness l every t years our findings confirm that mean catchment erosion rates may be reliably estimated from 10be concentrations in fluvial sediment in high relief rapidly eroding terrain these catchment wide integrated erosion rates can be calculated where erosion is primarily accomplished through shallow 3 m landslides are the dominant mode of erosion only minimum erosion rates can be determined lastly we present erosion rate measurements from the torrente catchment that reveal variation of two orders of magnitude 0 03 1 6 m ka 1 quantifying the high degree of spatial variation in erosion rates expected within rapidly uplifting catchments copyright 2006 john wiley sons ltd

a 30 000 yr record of erosion rates from cosmogenic 10be in middle european river terraces abstract cosmogenic 10 be in river borne quartz sand records a time integrated erosion rate representative of an entire drainage basin when sequestered in a terrace of known age paleo erosion rates may be recovered from the nuclide content of the terrace material paleo erosion rates between 30 and 80 mm kyr are determined from terrace sediments 200 to 30 000 yr in age of the allier and dore rivers france and the meuse maas river the netherlands erosion rates determined from cosmogenic nuclides on terraces from the allier river are consistent with rates derived from the sedimentary fill of a lake in the allier catchment a strong decrease in cosmogenic nuclide derived erosion rates from terraces of the meuse river with late pleistocene to holocene age is observed the paleo erosion signal from cosmogenic nuclides records projection of the elevated late pleistocene erosion rate into the time integrated rates derived from middle european rivers

numerical modeling of fluvial strath terrace formation in response to oscillating climate many river systems in western north america retain a fluvial strath terrace rec ord of discontinuous downcutting into bedrock through the quaternary their importance lies in their use to interpret climatic events in the headwaters and to determine long term incision rates terrace formation has been ascribed to changes in sediment supply and or water discharge produced by late quaternary climatic fluctuations we use a one dimensional channel evolution model to explore whether temporal variations in sediment and water discharge can generate terrace sequences the model includes sediment transport vertical bedrock erosion limited by alluvial cover and lateral valley wall erosion we set limits on our modeling by using data collected from the terraced wind river basin two types of experiments were performed constant period sinusoidal input histories and variable period inputs scaled by the marine 18 o rec ord our simulations indicate that strath terrace formation requires input variability that produces a changing ratio of vertical to lateral erosion rates straths are cut when the channel floor is protected from erosion by sediment and are abandoned and terraces formed when incision can resume following sediment cover thinning high sediment supply promotes wide valley floors that are abandoned as sediment supply decreases in contrast wide valleys are promoted by low effective water discharge and are abandoned as discharge increases widening of the valley floors that become terraces occurs over many thousands of years the transition from valley widening to downcutting and terrace creation occurs in response to subtle input changes affecting local divergence of sediment transport capacity formation of terraces lags by several thousand years the input changes that cause their formation our results suggest that use of terrace ages to set limits on the timing of a specific event must be done with the knowledge that the system can take thousands of years to respond to a perturbation the incision rate calculated in the field from the lowest terrace in these systems will likely be higher than the rate calculated by using older terraces because the most recent fluvial response in the field is commonly downcutting associated with declining sediment input since the last glacial maximum this apparent increase in incision rates is observed in many river systems and should not necessarily be interpreted as a response to an increase in rock uplift rate

7200 years of rhone river flooding activity in lake le bourget france a high resolution sediment record of nw alps hydrology magnetic susceptibility ms was measured with high resolution 5 mm on a 9 m long 14c dated core from lake le bourget savoie france spanning the last 7200 years the strong correlation r 0 85 of the ms with the silicate borne suite of elements si al fe mg k and anti correlation with the carbonate content r 0 87 allows it to be used as a proxy for the fluctuations of the abundance of riverborne clastic fraction versus authigenic carbonates in sediment as the rhone is the only river bringing a significant amount of silicate minerals to the coring site the ms downstream is interpreted as a proxy of the rhone suspended load discharge in lake le bourget this is confirmed over the last 3000 years by the good match with the evolution of hydrological activity of the rhone as it is known through geomorphological studies of well dated archaeological sites over the last 7200 years the record is consistent with the regional record of lake water level fluctuations while the intensity of the ms

the search for a topographic signature of life landscapes are shaped by the uplift deformation and breakdown of bedrock and the erosion transport and deposition of sediment life is important in all of these processes over short timescales the impact of life is quite apparent rock weathering soil formation and erosion slope stability and river dynamics are directly influenced by biotic processes that mediate chemical reactions dilate soil disrupt the ground surface and add strength with a weave of roots over geologic time biotic effects are less obvious but equally important biota affect climate and climatic conditions dictate the mechanisms and rates of erosion that control topographic evolution apart from the obvious influence of humans does the resulting landscape bear an unmistakable stamp of life the influence of life on topography is a topic that has remained largely unexplored erosion laws that explicitly include biotic effects are needed to explore how intrinsically small scale biotic processes can influence the form of entire landscapes and to determine whether these processes create a distinctive topography

mineral magnetic characterization of sediment sources from an analysis of lake and floodplain sediments in the catchments of the old mill reservoir and slapton ley south devon uk research on suspended sediment transport in the catchments of the old mill reservoir and slapton lower ley south devon has attempted to discriminate changing catchment sources on the basis of downcore variations in the mineral magnetic properties of lake reservoir and floodplain sediments here we examine these downcore variations and also explore the variability in catchment sources and the influence of topographic controls on mineral magnetic signatures of topsoils and subsoils particle size controls on the mineral magnetic signatures are explored by an analysis of a fractionated sediment sample whilst the possible impact of diagenesis is assessed by an examination of the mn profiles in the lake and reservoir sediments from this analysis it is evident that the mineral magnetic signatures of well sorted floodplain deposits are more likely to reflect the particle size composition of the transported material by contrast the mineral magnetic record in the sediment of slapton ley appears to be most strongly influenced by dissolution of magnetic minerals the sediment of the old mill reservoir provides the only suitable record for the application of a simple mixing model which is developed in order to quantify changes in the relative contribution of topsoil and subsoil through time the research has important implications for attempting to reconstruct sediment sources in highly eutrophic lakes and emphasizes the uncertainty in the application of simple mixing models 1998 john wiley sons ltd

sediment characteristics and sedimentations rates of a small river in western central brazil the purpose of this study is to characterise the alluvial sediments and to quantify sedimentation rates of a small river system the ribeirao do torto in central western brazil the study area provides an excellent opportunity to examine the effect of land use on sedimentation rates in the region for the first time and thus contributes to understanding sediment transport processes into water reservoirs silting 137cs 210pb and 14c dating techniques were used to estimate natural sedimentation rates and those associated with land use development complementary use of physical and chemical analyses of the sediments and contained anthropogenic materials revealed that sedimentation dynamics had varied over time natural sedimentation rates are more than ten times lower than in the period since the mid 1950s for the alluvial system of the ribeirao do torto the results indicated that human impact had accelerated the sedimentation dynamics which resulted in higher sediment quantities and sand content and changes of sediment sources the variation of sedimentation rates may reflect also several other factors e g natural fluctuation in flow energy or geomorphologic changes within the alluvial system however the multiple dating techniques and supplementary interpretation employed in this study show the potential use of radionuclides and soil sediment parameters to identify changes in sedimentation rate stream energy and sediment characteristics in floodplains

use of fallout 137cs in investigations of overbank sediment deposition on river floodplains abstract river floodplains have been recognised as important sinks for storing suspended sediment and associated contaminants mobilised from the upstream catchment however information on contemporary rates of overbank sedimentation is difficult to obtain using conventional methods measurements of the 137cs content of floodplain sediments provide an alternative approach to obtaining estimates of medium term rates ca 40 years of overbank sediment deposition the 137cs approach requires only a single site visit and minimum sample preparation furthermore it is capable of providing information on spatial patterns of sediment deposition on floodplains which is needed to improve our understanding of the processes involved in overbank flow and sediment deposition this paper reviews the basis for using 137cs measurements in floodplain sedimentation studies and presents improved procedures for interpreting 137cs profiles in floodplain sediments and for obtaining estimates of sedimentation rates from single measurements of the total 137cs inventories of bulk sediment cores the results obtained from a case study undertaken on the floodplain of the river stour dorset uk are presented

land use and climatic impacts on the rhine system rheinlucifs quantifying sediment fluxes and human impact with available data abstract the rheinlucif project investigates the effects of land use and climatic impacts on sediment fluxes in the river rhine catchment among the world s large rivers the rhine system has been particularly affected by land use changes for 7500 years resulting in its transformation to an entirely man controlled environment geomorphologically this transformation is performed by largely man induced sediment fluxes since the mid holocene as the large scale of the rhine catchment inhibits a renewed recording of stratigraphic records the main goal is to synthesize quantitative data on sediment flux climatic and human impacts from already available data from various fields of earth surface and social sciences particularly history and archaeology this paper presents the first steps and results of methodological groundwork exploring how to derive sediment budgets from available spatially distributed data soil maps geological maps dems furthermore a new basically statistical approach utilising archaeological data is outlined this approach provides time series of quantified human impact i e information on population densities and open land woodland ratios the first results derived from four different sediment budget approaches are helpful in order to assess the quality of available data for budget calculation purposes although some estimates on erosion and alluvial deposition seem to broadly agree a considerable disparity of holocene erosion and colluviation values occurs when these values are compared to the outcome of an independently recorded soil mapping campaign in a pilot area however in general the results suggest that all applied approaches chiefly require an improved estimation of sediment storage on the one hand this accounts for the need of more precise information on holocene floodplain deposits on the other hand as the larger portion of man induced sediments still resides in the sloping parts of catchments realistic estimates on man induced colluvial deposition on slopes are essential apart from budgeting issues all data on holocene erosion and sedimentation in the rhine catchment lacked a sufficient dating control therefore further investigations on fluxes between budget components necessitate additional datings quantified data on human impact is indispensable to the modelling of sediment fluxes because human impact is deemed to be the major driving force of sediment production and re distribution although the archaeological approach was developed and tested by utilising well documented data about the neolithic era the promising statistical evaluation suggests that this method can be applied to even less well documented proto prehistoric and historic periods

spatially averaged long term erosion rates measured from in situ produced cosmogenic nuclides in alluvial sediment spatially averaged erosion rates of small catchments can be accurately inferred from the concentrations of cosmogenic nuclides in stream sediment here we test this technique at two catchments by comparing erosion rates inferred from cosmogenic nuclides with rates of alluvial fan deposition over the past 16 000 years these two independent estimates agree within one standard error demonstrating that cosmogenic nuclide signatures of stream sediment can be used to measure spatially averaged long term erosion rates using this technique we show that long term erosion rates are an exponential function of average hillslope gradient at these sites

later pleistocene evolution of the exe valley a chronstratigraphic model of terrace formation and its implications for palaeolithic archaeology this paper presents the first systematic chronostratigraphic study of the river terraces of the exe catchment in south west england and a new conceptual model for terrace formation in unglaciated basins with applicability to terrace staircase sequences elsewhere the exe catchment lay beyond the maximum extent of pleistocene ice sheets and the drainage pattern evolved from the tertiary to the middle pleistocene by which time the major valley systems were in place and downcutting began to create a staircase of strath terraces the higher terraces 8 6 typically exhibit altitudinal overlap or appear to be draped over the landscape whilst the middle terraces show greater altitudinal separation and the lowest terraces are of a cut and fill form the terrace deposits investigated in this study were deposited in cold phases of the glacial interglacial milankovitch climatic cycles with the lowest four being deposited in the devensian marine isotope stages mis 4 2 a new cascade process response model is proposed of basin terrace evolution in the exe valley which emphasises the role of lateral erosion in the creation of strath terraces and the reworking of inherited resistant lithological components down through the staircase the resultant emergent valley topography and the reworking of artefacts along with gravel clasts have important implications for the dating of hominin presence and the local landscapes they inhabited whilst the terrace chronology suggested here is still not as detailed as that for the thames or the solent system it does indicate a middle palaeolithic hominin presence in the region probably prior to the late wolstonian complex or mis 6 this supports existing data from cave sites in south west england

dating fluvial terraces by 230th u on pedogenic carbonate wind river basin wyoming abstract reliable and precise ages of quaternary pedogenic carbonate can be obtained with 230th u dating by thermal ionization mass spectrometry applied to carefully selected milligram size samples datable carbonate can form within a few thousand years of surface stabilization allowing ages of quaternary deposits and surfaces to be closely estimated pedogenic carbonate clast rinds from gravels of glacio fluvial terraces in the wind river basin have median concentrations of 14 ppm u and 0 07 ppm 232th with median 230th 232th 270 making them well suited for 230th u dating horizons as thin as 0 5 mm were sampled from polished slabs to reduce averaging of long 105 yr and sometimes visibly discontinuous depositional histories dense translucent samples with finite 230th u ages preserve within rind stratigraphic order in all cases ages for terraces wr4 167 000 6 400 yr and wr2 55 000 8600 yr indicate a mean incision rate of 0 26 0 05 m per thousand years for the wind river over the past glacial cycle slower than inferred from cosmogenic nuclide dating terrace wr3 which formed penecontemporaneously with the final maximum glacial advance of the penultimate rocky mountain bull lake glaciation has an age of 150 000 8300 yr indicating that it is broadly synchronous with the penultimate global ice volume maximum

an approximation of the sediment budget of the lower mississippi river prior to major human modification a sediment budget is constructed for the lower mississippi river prior to the introduction of most human modifications components of the budget are derived from historical data including mississippi river commission hydrographic survey maps for the period from 1877 to 1924 a quantitative estimate of major sediment sources sinks and storage locations in the lower mississippi valley suggest that the most important sediment source was from bank caving and that at least 50 per cent more sediment was deposited in short term channel storage than in longer term overbank storage the budget indicates that the proportion of sediment transported as bedload was significantly greater than previously estimated the magnitude and variability of these sediment budget components are discussed the results of the study suggest that prior to modifications the river was aggrading over much of its length

estimating rates of denudation using cosmogenic isotope abundances in sediment we propose as a testable hypothesis a basin scale approach for interpreting the abundance of in situ produced cosmogenic isotopes an approach which considers explicitly both the isotope and sediment flux through a drainage basin unlike most existing models which are appropriate for evaluating in situ produced cosmogenic isotope abundance at discrete points on earth s surface our model is designed for interpreting isotope abundance in sediment because sediment is a mixture of materials in favourable cases derived from throughout a drainage basin we suggest that measured isotope abundances may reflect spatially averaged rates of erosion we investigate the assumptions and behaviour of our model and conclude that it could provide geomorphologists with a relatively simple means by which to constrain the rate of landscape evolution if a basin is in isotopic steady state and if sampled sediments are well mixed

seismic reflection investigations of a bedrock surface buried under alluvium seismic reflection techniques were used to characterize a bedrock surface buried under alluvium near a construction site on the campus of baylor university in waco texas one of the objectives of the study was to determine if either compressional or shear seismic profiling could be used to reduce the number of engineering boreholes required to determine the bedrock depth and relief prior to building construction the upper few meters of the alluvium is dry but the lower portion is below the water table making the bedrock surface a difficult target for compressional waves the compressional reflection coefficient at the water table is an order of magnitude greater than that at the bedrock surface and the dry alluvium reduces the signal bandwidth such that the two reflections cannot be distinguished also the multimode rayleigh ground roll traveling along the surface at about half the speed of the compressional wave swamps the reflections by using shear waves to profile the alluvium bedrock interface

late weichselian and holocene palaeogeography of the rhine meuse delta the netherlands abstract a large number of lithological borehole descriptions 14c dates archaeological artefacts and gradients of palaeochannels were used to reconstruct the holocene development of the rhine meuse delta data were stored in a geographical information system database that enables generation of palaeogeographical maps for any time during the holocene the time resolution of the palaeogeographic reconstruction is about 200 years during the holocene avulsion was an important process resulting in frequent shifts of areas of clastic sedimentation palaeogeographic evolution of the rhine meuse delta is mainly governed by complex interactions among several factors these are 1 location and shape of the late weichselian palaeovalley 2 sea level rise which resulted in back filling of the palaeovalley 3 peat formation which was most extensive in the western part of the back barrier area especially between 4000 and 3000 14c yr bp this more or less fixed the river pattern at that time and resulted in few avulsions 4 neotectonics differential tectonic movements of the peel horst and roer valley graben seem to have influenced river behaviour formation of an asymmetrical meander belt location of avulsion nodes especially from 4500 to 2800 14c yr bp when the rate of sea level rise had decreased after 2800 14c yr bp the sea level rise further decreased and the tectonic influence still may have influenced avulsions but from then on other factors became dominant 5 increased discharge sediment load and or within channel sedimentation after 2800 14c yr bp river meanders of rhine distributaries as well as the single channel of the meuse show remarkable increases in wavelength interpreted as a result of increased bankfull discharge and sediment load increased discharge may initially have been caused by a higher precipitation after 2000 14c yr bp both discharge and sediment load seem to have increased as a result of human influence alternatively decreasing gradients as a result of sea level rise may have caused an increased within channel sedimentation and channel widening which would also lead to increased meander wavelengths 6 composition of the river banks meandering river channels tend to adhere to the sandy margins of the late weichselian palaeovalley and a high channel sinuosity is found in areas where river banks consist of sand 7 marine ingressions e g the ad 1421 st elizabeth s flood caused large scale erosion in the southwestern part of the fluvial deltaic plain 8 human influence since about ad 1100 human influence dominated the palaeogeographic evolution rivers were embanked and dredged meanders were cut off and for the meuse a new distributary canal the bergsche maas was dug in ad 1904 discharge distribution over the various channels is strictly controlled nowadays an unusual feature of the delta is the prolonged existence of the oude rijn channel belt

radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired 230 th 234 u 238 u and 14 c dates on pristine corals abstract radiocarbon dating is the most widely used dating technique in the world recent advances in accelerator mass spectrometry ams and sample preparation techniques have reduced the sample size requirements by a factor of 1000 and decreased the measurement time from weeks to minutes today it is estimated that more than 90 percent of all measurements made on accelerator mass spectrometers are for radiocarbon age dates the production of 14 c in the atmosphere varies through time due to changes in the earth s geomagnetic field intensity and in its concentration which is regulated by the carbon cycle as a result of these two variables a radiocarbon age is not equivalent to a calendar age four decades of joint research by the dendrochronology and radiocarbon communities have produced a radiocarbon calibration data set of remarkable precision and accuracy extending from the present to approximately 12 000 calendar years before present this paper presents high precision paired 230 th 234 u 238 u and 14 c age determinations on pristine coral samples that enable us to extend the radiocarbon calibration curve from 12 000 to 50 000 years before present we developed a statistical model to properly estimate sample age conversion from radiocarbon years to calendar years taking full account of combined errors in input ages and calibration uncertainties our radiocarbon calibration program is publicly accessible at http www radiocarbon ldeo columbia edu along with full documentation of the samples data and our statistical calibration model

system dynamics and environmental change an exploratory study of holocene lake sediments at holzmaar germany the idea that much environmental information may be gained by identifying underlying environmen tal system behaviours is examined six categories of system behaviour for changes between and within steady states are identified disorder maximization self organization linear process response stochastic self organized criticality and chaotic in practical terms predictability only exists for linear behaviour simple frequency distributions of time series data are used to identify dominant behaviour in the proxy records from 10 000 years of annual laminations from holzmaar germany the results suggest that before 3000 yr cal bp the catchment lake system may have reached a state of self organized criticality where fluctuations in system properties for instance diatom productivity and sediment flux were caused by internal reorganization as much as by external forces comparison of the records for sediment flux with outputs from the golem landscape model suggests that major shifts in the holocene rec

use of fallout pb 210 measurements to investigate longer term rates and patterns of overbank sediment deposition on the floodplains of lowland rivers the potential for using fallout unsupported pb 210 210pb measurements to estimate rates of overbank sediment deposition on the floodplains of lowland rivers is explored a model which distinguishes the contribution from direct atmospheric fallout and the catchment derived input associated with the deposition of suspended sediment has been developed to interpret the fallout pb 210 inventories at floodplain sampling sites and to estimate average sediment accumulation rates over the past 100 years the approach has been successfully used to estimate rates of overbank sedimentation on the floodplains of the rivers culm and exe in devon u k a detailed investigation of the pattern of longer term sedimentation rates within a small reach of the floodplain of the river culm indicated a range of deposition rates between 0 07 and 0 59 g cm 2 a 1 which was in close agreement with estimates of current sedimentation rates obtained using sedimentation traps

the sediment budget of a highly dynamic mesoscale catchment the river isabena the paper presents the sediment budget of the isabena basin a highly dynamic 445 km2 catchment located in the central pyrenees that is patched by highly erodible areas i e badlands the budget for the period 2007 2009 is constructed following a methodology that allows the interpolation of intermittent measurements of suspended sediment concentrations and enables a subsequent calculation of sediment loads data allow specification of the contribution of each subbasin to the water and sediment yield in the catchment outlet mean annual sediment load was 235 000 t y 1 specific sediment yield reached 2000 t km 2 y 1 a value that indicates very high sedimentary activity especially in the case of villacarli and lascuarre subcatchments were most badlands are located the specific sediment yield obtained for the entire isabena is 527 t km 2 y 1 a high value for such a mesoscale basin results show that a small part of the area i e 1 controls most of the catchment s gross sediment contribution sediment delivery ratio ratio between sediment input from primary sources and basin export has been estimated at around 90 while in channel storage represents the 5 of the annual load on average the high connectivity between sediment sources i e badlands and transfer paths i e streamcourses exacerbates the influence of the local sediment production on the catchment s sediment yield a quite unusual fact for a basin of this scale

comment on radiocarbon calibration curve spanning 0 to 50 000 years bp based on paired th 230 u 234 u 238 and c 14 dates on pristine corals by r g fairbanks et al quaternary science reviews 24 2005 1781 1796 and extending the radiocarbon calibration beyond 26 000 years before present using fossil corals by t c chin et al quaternary science reviews 24 2005 1797 1808

the history of holocene soil erosion in the phlious basin ne peloponnese greece based on optical dating anthropogenic induced soil erosion has occurred in the mediterranean during historic and pre historic times but precise timeframes for periods of past soil erosion are largely missing due to the lack of datable material and suitable dating methods in this study optical dating of colluvial sediments from the phlious basin ne peloponnese greece was applied the results show that soil erosion derived colluvium formed under a mediterranean type climate can be successfully dated by optical stimulated luminescence osl and a high resolution chronology of holocene soil erosion could be established colluvial formation occurred in the early holocene but increased distinctly in the seventh millennium parallel with the onset of the neolithic the start of farming activities other periods of strong colluviation are the middle and late bronze age second millennium the roman period first century to sixth century and the period since the sixteenth century rates of reduced colluviation occurred during

cumulative probability functions and their role in evaluating the chronology of geomorphological events during the holocene cumulative probability functions cpfs for large numbers of radiocarbon age determinations are increasingly being used by scientists as a methodology to discern environmental histories while the recent compilation of regional databases of the radiocarbon dating control for fluvial sediment sequences has been beneficial for identifying gaps in knowledge and stimulating new research there are a number of problems that critically undermine the use of these cpfs as sensitive hydroclimatic proxies i the cpf method is underpinned by the assumption that each radiocarbon measurement is a true age estimate for a point in time whereas each measured age in fact forms a scatter around the true age of the sample ii calibration of radiocarbon ages is responsible for much of the structure in cpfs and compounds the problem of scatter and smears the chronological control iii the databases incorporate multiple types of environmental changes differing chronological relationships between the 14c measurements and the dated events with pre dating dating or post dating chronological control each displaying variable length temporal lags all mixed together in the same analysis and iv the radiocarbon ages from individual case studies need to be more robustly tested before being incorporated into regional databases all these factors negate the value of cpfs as sensitive proxies of environmental change because peaks in probability for individual radiocarbon measurements are likely to be an incorrect estimate for the age of a geomorphological event and this problem is compounded by combining probabilities for multiple unrelated events in this paper we present a critical analysis of cpfs and their interpretation before suggesting alternative approaches to analysing radiocarbon geochronologies of geomorphic events which include i bayesian age modelling of river terrace development ii developing regional databases that test specific geomorphic hypotheses iii bayesian age modelling of palaeoflood records and iv analysis of sedimentation rates copyright 2011 john wiley sons ltd

using unsupported lead 210 measurements to investigate soil erosion and sediment delivery in a small zambian catchment abstract traditional techniques used to assemble information on rates of erosion and soil redistribution possess many important limitations as a result the use of environmental radionuclides and more particularly 137 cs measurements has attracted increasing attention in recent years as a means of obtaining spatially distributed information on rates of erosion and deposition the application of the 137 cs approach is however hampered in some areas of the world where 137 cs inventories are low and the low concentrations of 137 cs found in soils and sediments cause problems for laboratory analysis these problems will increase as time progresses due to the radioactive decay of the existing inventory most of which was deposited as fallout ca 40 years ago this contribution explores the potential for using another fallout radionuclide namely unsupported 210 pb as an alternative to 137 cs in the small 63 km 2 upper kaleya catchment in southern zambia where 137 cs inventories are already very low the approach employed with unsupported 210 pb is similar to that used for 137 cs although the essentially constant fallout of unsupported 210 pb through time means that the resulting estimates of erosion and soil redistribution rates reflect a longer period of time ca 100 years rather than ca 40 years the estimates of erosion and deposition rates derived from the unsupported 210 pb measurements are used to construct typical sediment budgets for the three main land use types in the upper kaleya catchment namely commercial cultivation communal cultivation and bush grazing the results obtained from the unsupported 210 pb are compared with equivalent results based on 137 cs measurements provided by a previous investigation undertaken in the study catchment the two sets of results are highly consistent the study reported confirms the viability of using unsupported 210 pb as an alternative to 137 cs in this environment and demonstrates that conjunctive use of both radionuclides can provide additional information on the erosional history of a study area