back to the past symbolism and archaeology in altxerri b gipuzkoa northern spain abstract in a previous publication on altxerri b cave we explained a chronological hypothesis which proposed that the graphic activity in the site dates to an early aurignacian phase this paper presents a complete study of the parietal ensemble including descriptions of the graphic motifs and other anthropic evidence that has been documented the number of figures identified in the only panel documented in previous studies has been increased considerably while several previously unpublished panels in other parts of the cave are described the iconographic and stylistic characteristics of the rock art far from contradicting our first conclusions about the chronology support these and link the art in altxerri b with other european early upper palaeolithic graphic ensembles

tunnel development over a 12 year period in a semi arid catchment of the loess plateau china the tunnel systems in a semi arid catchment of the loess plateau of china were repeatedly surveyed prior to the rainy seasons of 1989 1999 and 2001 the surveys aimed to 1 measure tunnel development over the 12 year period 1989 2001 2 explore how the physiographical conditions affect the spatio temporal variability of tunnel development and 3 to identify the geomorphic processes associated with tunnel development the ultimate goal was to quantify the geomorphic significance of tunnel systems in the catchment over the 12 year period the number of tunnel inlets was more than doubled and most of the newly increased inlets were initiated in the few catastrophic storm events however tunnel enlargement can occur in storm or inter storm periods mainly through earth falls and slumps in inlets and water erosion and roof cave in collapses in tunnel paths tunnel development varied with material properties land uses and topographic conditions net tunnel erosion may contribute at least 25 30 of the catchment sediment yield and was mainly produced by the initiation and enlargement of tunnel inlets rather than tunnel paths to protect the areas against tunnel erosion terracing of the upper slopes seems to be more effective than planting vegetation on the lower slopes copyright 2003 john wiley sons ltd

quantitative assessment of the piping erosion susceptibility of loess derived soil horizons using the pinhole test abstract the pinhole test is an empirical test based on the qualitative evaluation of the dispersivity colloidal erodibility of compacted fined grained soils this paper evaluates the pinhole test device for the quantitative assessment of the susceptibility of soil horizons to piping assesses the effects of hydraulic head water quality antecedent soil moisture content and soil disturbance on the hydrological and erosion response during pipeflow and formulates recommendations for the application of the pinhole test to study piping erosion processes in total 255 pinhole test experiments were conducted the results obtained from disturbed soil samples ap horizon indicate i a significant positive linear increase in pipeflow discharge qw and sediment discharge qs with increasing hydraulic head ii no relationship between qw and antecedent soil moisture content asm but significant and negative relationship between qs and asm and iii significantly higher qs for distilled water than for tap water the use of disturbed soil samples resulted in significantly more rapid flow responses and lower sediment discharges than for undisturbed soil samples the pinhole test experiments performed on different loess derived soil horizons show that the plowed topsoil ap and the underlying clay enriched horizon bt are at least two times less susceptible to piping than the decalcified c1 and the calcareous horizons c2 this confirms field observations indicating that loess derived soil horizons are very susceptible for piping erosion especially when the c horizon crops out this study demonstrates that the pinhole test is suitable for assessing the susceptibility of soil horizons to piping in a quantitative way i e qw qs the time to outflow and the cross section of the pipe after the test we recommend the use of i two different hydraulic heads i e 180 and 1020 mm ii distilled water iii contrasting antecedent soil moisture contents of the soil samples to be tested and iv different soil sampling methods to investigate the effect of soil disturbance and particularly to obtain a better understanding of the sediment response during pipeflow

hydrological response of loess slopes with reference to widespread landslide events in the heifangtai terrace nw china abstract in the heifangtai terrace nw china flooding irrigation is common for the cropland production and has increased the groundwater table by 20 30 m over the past five decades it is believed that excessive irrigation has induced a large number of loess landslides in this area however these loess landslides responses to hydrological changes have still not been well understood therefore 43 boreholes and 51 2d electrical resistivity tomography ert profiles with a total length of 40 km have been investigated to analyze the hydrological characteristics for the whole terrace and characterize the effects of hydrological changes on the occurrence of different types of loess landslides our main findings are as follows 1 three groundwater domes are found in the center and eastern part of the heitai terrace and the groundwater table is gradually rising in the whole terrace based on the ert results 2 the rising rate of groundwater table at the center of the terrace is twice greater than that at the margin of the terrace and it takes approximately 4 months for irrigation water to penetrate from the top surface to the saturated layer 3 landslide deposits could block drainage channels of groundwater increase the localized hydraulic gradient and result in rising of local groundwater table at the edge of the terrace 4 the resultant hydraulic gradient impels the groundwater from the center to seep out on the eastern and southern margins and new landslides are prone to occur in the main scarp of landslides with rising groundwater table the type and magnitude of landslides are affected by groundwater seepage and movement in order to fundamentally control the occurrence of landslides effective drainage system and the restrained amount of irrigation water are needed

impact of soil characteristics and land use on pipe erosion in a temperate humid climate field studies in belgium abstract this study investigates the role of soil characteristics and land use in the development of soil pipes in the loess belt of belgium first we tested the hypothesis that discontinuities in the soil profile enhance lateral flow and piping by impeding vertical infiltration we focus on discontinuities in soil characteristics that can vary with soil depth including texture saturated hydraulic conductivity penetration resistance and bulk density these characteristics as well as soil biological activity were studied in detail on 12 representative soil profiles for different land use types twelve sites were selected in the flemish ardennes belgium four pastures with collapsed pipes cp four pastures without cp two sites under arable land without cp and two sites under forest without cp secondly this study aimed at evaluating the interaction of groundwater table positions through soil augerings and cp in a larger area with a focus on pastures pasture is the land use where almost all cp in the study area are observed therefore the position of the groundwater table was compared for 15 pastures with cp and 14 pastures without cp having comparable topographical characteristics in terms of slope gradient and contributing area finally the effect of land use history on the occurrence of pipe collapse was evaluated for a database of 84 parcels with cp and 84 parcels without cp currently under pasture as to the first hypothesis no clear discontinuities for abiotic soil characteristics in soil profiles were observed at the depth where pipes occur but pastures with cp had significantly more earthworm channels and mole burrows at larger depths 120 cm mean of 200 earthworm channels per m 2 than pastures without cp arable land or forest 120 cm depth a few or no earthworm channels left the land use history appeared to be similar for the pastures with and without cp combining all results from soil profiles and soil augering indicates that intense biological activity especially by earthworms and moles in combination with a sufficiently high groundwater table favours the development of soil pipes in the study area

impact of piping on gully development in mid altitude mountains under a temperate climate a dendrogeomorphological approach abstract gullies are complex geomorphic systems induced and transformed not only by surface erosion processes but also by subsurface processes such as piping however the transient nature of piping makes this process more difficult to observe and study especially when a pipe roof has totally collapsed this study aims at assessing piping impact on gully initiation and development using dendrogeomorphological analyses which are a novel approach in piping study the survey was carried out in a mountainous area under a temperate climate using the bere nica wyzna catchment in the bieszczady mts eastern carpathians as a case study we estimated the minimum age of pipe collapses and presented the transformation of pipe collapses in order to identify the direction of pipe and gully development we also verified the contribution of piping to gully development by the reconstruction of gully bottom deepening the analysis was based on changes in tree and root wood anatomy in diffuse porous deciduous angiosperm species i e common alder alnus glutinosa and field maple acer campestre the pipe collapses in the piping system studied are at least 19 to 23 27 years old and the pipe roof initially collapsed in the lower sections of the slope above the gully head and the pipe develops up the slope by headward erosion the gully that was analysed in forest had been deepened by piping during several episodes connected with high precipitation events in contrast the pipe located in grasslands collapsed 1 2 years after such events indicating that dense vegetation delays pipe collapse this study shows that dendrogeomorphological analyses based on diffuse porous deciduous angiosperm species may be a useful tool in piping research it provides information on pipe and gully development as well as enabling estimates to be made of the age of pipe collapses

factors underlying piping in the basilicata region southern italy abstract piping tunnelling erosion is a widely spread process in the plio pleistocene marine clays of the basilicata region in southern italy the pipes are often closely concentrated along the surface drainage networks at different depths with a tunnel length and a diameter varying from just a few centimetres to some metres the formation and evolution of pipes in the badlands can be explained through 1 geo structural characteristics of the clay 2 material properties such as a high exchangeable sodium percentage 3 favourable climatic conditions and 4 hydraulic gradient along the path controlled by the gully or ravine bottom that is acting as a local drain the exposure and the extension of joints at the surface and in the bedrock along the slope are the main factors required for development of the pipes the absence of the piping erosion on the slopes where a reasonably thick layer of the soil material covers the open joints shows that although certain material properties and climatic conditions play an important role they are not sufficient to develop extensive piping erosion in the area

gully and tunnel erosion in the hilly loess plateau region china article i nfo article history although gully development is frequently observed to be associated with piping and tunnel erosion in many parts of the world there is a lack of detailed studies on their spatial interactions such studies not only con tribute to developing geomorphic theories on the evolution of both hillslopes and drainage networks but also are useful to design effective control measures of erosion the present study aims to examine the interactions between gully development and tunnel erosion in the hilly loess plateau region of northern china firstly gullies tunnel inlets and mass movements in the 9 1 km 2 wangjiagou watershed were mapped through ae rial photo interpretation and reconnaissance surveys secondly detailed field studies were carried out to in vestigate the interactions between gully development and tunnel formation processes in the selected gullies thirdly the physiographic variables of gullies derived from gis and field measurements were analyzed to identify differences between tunneled and untunneled gullies a total of 704 channels 967 tunnel inlets and 547 mass movements were identified in the study watershed on the basis of their location and morphology all the channels were classified into four types headwater gullies hillside gullies valleyside gullies and ephemeral river channels tunnels are associated with 79 of headwater gullies 48 of hillside gullies 3 of valleyside gullies and none of ephemeral river channels mass movements are dominated by falls in headwater gullies falls and slides in hillside gullies and soil creeps in ephemeral stream channels statistical tests indicate that there are significant differences in phys iographic variables between tunneled and untunneled gullies tunnel formation in gullies is intricately affect ed by topographic conditions land uses knickpoint distribution soil materials and mass movements published by elsevier b v

combining geomorphological mapping and near surface geophysics gpr and ert to study piping systems abstract this paper aims to provide a more comprehensive characterization of piping systems in mountainous areas under a temperate climate using geomorphological mapping and geophysical methods electrical resistivity tomography ert and ground penetrating radar gpr the significance of piping in gully formation and hillslope hydrology has been discussed for many years and most of the studies are based on surface investigations however it seems that most surface investigations underestimate this subsurface process therefore our purpose was to estimate the scale of piping activity based on both surface and subsurface investigations we used geophysical methods to detect the boundary of lateral water movement fostering pipe development and recognize the internal structure of the underlying materials the survey was carried out in the bere nica wyzna catchment in the bieszczady mountains eastern carpathians poland where pipes develop in cambisols at a mean depth of about 0 7 0 8 m the geophysical techniques that were used are shown to be successful in identifying pipes gpr data suggest that the density of piping systems is much larger than that detectible from surface observations alone pipe length can be 6 5 9 2 maximum 49 higher than what surface mapping suggests thus the significance of piping in hillslope hydrology and gully formation can be greater than previously assumed these results also draw attention to the scale of piping activity in the carpathians where this process has been neglected for many years the ert profiles reveal areas affected by piping as places of higher resistivity values which are an effect of a higher content of air filled pores due to higher soil porosity intense biological activity and well developed soil structure in addition the ert profiles show that the pipes in the study area develop at the soil bedrock interface probably above the layers of shales or mudstones which create a water restrictive layer our results illustrate the suitability and limitations of gpr and ert to study soil piping in general geophysical surveying is useful for gathering more information on pipe density potential pipe detection and recognition of the internal structure of materials underlying the pipes however the interpretation of radargrams and ert profiles should be always accompanied by detailed terrain mapping due to potential disturbances affecting geophysical profiles

the nature of the fluids associated with the monte rosa gold district nw alps italy recent o isotope and fluid inclusion studies have provided evidence on the nature of the fluids associated with the late alpine quartz gold deposits of the monte rosa district the most abundant inclusions in quartz from these deposits contain a low salinity aqueous fluid about 2 to 10 wt nacl eq and a co2 phase usually less than 20 mol in places with minor methane co2 densities and total homogenization temperatures vary widely throughout the district reflecting diverse conditions of trapping p 1 to 3 kb t 300 to 450 c at miniera dei cani unmixing between co2 rich and h2o rich fluids possibly occurred a second type of inclusion contains an aqueous brine without recognizable co2 and is especially abundant at val toppa o isotope studies suggest that fluids were largely equilibrated in a metamorphic environment it is concluded that the gold related fluids in the district were mainly of a metamorphic nature at val toppa both isotopic and fluid inclusion data point to contributions of unexchanged meteoric waters mechanisms of gold transport and precipitation are less contrained a possible model involves transport of gold as bisulfide complexes and precipitation due to one or more of the following processes decrease of sulfur activity due to precipitation of sulfides wall rock reaction cooling dilution and or fluid unmixing

spatial interaction between collapsed pipes and landslides in hilly regions with loess derived soils while most studies focus on the effect of soil pipes on hillslope stability this present study investigates the impact of landsliding on pipe development it is hypothesized that poorly drained active and dormant landslides change the hillslope hydrology through i surface flow obstruction by changing topography as well as ii subsurface flow obstruction by tilting less permeable clay rich substrates hence new preferential flow paths are created at reverse slopes within the landslide zone and at the boundary of the landslide enhancing pipe formation this study aims at a better understanding of the interaction between collapsed pipe cp occurrence and landslide ls occurrence in the flemish ardennes belgium by comparing their respective spatial patterns at least 24 5 of the 139 sites with cp were related to the occurrence of an observed ls poorly drained ls may create favourable conditions for pipe development outside ls natural and anthropogenic e g broken field drains road drainage causes may result in concentrated subsurface flow resulting in pipe development no evidence was found that pipe development enhanced ls probably because the subsurface drainage discharge generated upslope of the ls is too low even when pipes become blocked it is more likely that new pipes develop and new collapses occur than they trigger or reactivate ls a conceptual model is presented summarizing all elements that influence piping erosion in the flemish ardennes including the role of ls copyright 2012 john wiley sons ltd

loess erosion patterns on a cut slope revealed by lidar scanning abstract erosion is a major environmental issue on the chinese loess plateau although the erosion intensity on the plateau has generally decreased in recent years ongoing mega engineering projects continuously produce large bare and steep loess cut slopes that are prone to erosion therefore investigating loess erosion on cut slopes in this region has practical importance multi temporal high resolution digital elevation model dem analysis has been widely used to quantify surface erosion but has not yet been applied to loess cut slopes this study aims to reveal the spatial and temporal patterns of loess erosion on an artificial cut slope through the analysis of a time series of lidar scans the results showed that the spatial distribution of loess erosion on the study cut slope was constrained by three slope characteristics slope material slope structure and slope hydrology the highest erosion rates were observed in areas with paleosols discontinuities and water accumulation in the temporal domain the variation of the loess erosion rate with rainfall intensity could be described using a power function although this research only focused on one slope findings suggest that it is possible to investigate the complex loess erosion on cut slopes using state of the art high resolution remote sensing techniques such as lidar scanning our results provide useful information for soil conservation on similar engineering loess cut slopes in the loess plateau

regional mapping of soil parent material by machine learning based on point data abstract a machine learning system mart has been used to predict soil parent material spm at the regional scale with a 50 m resolution the use of point specific soil observations as training data was tested as a replacement for the soil maps introduced in previous studies with the aim of generating a more even distribution of training data over the study area and reducing information uncertainty the 27 020 km2 study area brittany northwestern france contains mainly metamorphic igneous and sedimentary substrates however superficial deposits aeolian loam colluvial and alluvial deposits very often represent the actual spm and are typically under represented in existing geological maps in order to calibrate the predictive model a total of 4920 point soil descriptions were used as training data along with 17 environmental predictors terrain attributes derived from a 50 m dem as well as emissions of k th and u obtained by means of airborne gamma ray spectrometry geological variables at the 1 250 000 scale and land use maps obtained by remote sensing model predictions were then compared i during spm model creation to point data not used in model calibration internal validation ii to the entire point dataset point validation and iii to existing detailed soil maps external validation the internal point and external validation accuracy rates were 56 81 and 54 respectively aeolian loam was one of the three most closely predicted substrates poor prediction results were associated with uncommon materials and areas with high geological complexity i e areas where existing maps used for external validation were also imprecise the resultant predictive map turned out to be more accurate than existing geological maps and moreover indicated surface deposits whose spatial coverage is consistent with actual knowledge of the area this method proves quite useful in predicting spm within areas where conventional mapping techniques might be too costly or lengthy or where soil maps are insufficient for use as training data in addition this method allows producing repeatable and interpretable results whose accuracy can be assessed objectively

understanding soil pipe flow and its role in ephemeral gully erosion the role of soil pipeflow in ephemeral gully erosion is not well understood experiments were conducted on continuous soil pipes to better understand the role of internal erosion of soil pipes and its relation to ephemeral gully development soil beds of 140 cm length 100 cm width and 20 cm depth had a single soil pipe of different initial sizes 2 4 6 8 and 10 mm diameter extend from a water reservoir to the outlet experiments were run on providence silt loam and smithdale loam soils under a constant head of 15 cm established for 30 min either the tunnel collapsed or the head could not be maintained soil pipes that were initially 2 and 4 mm clogged instantaneously at their mouth and did not exhibit flow whereas pipes initially 6 mm enlarged by 268 397 and 699 on average for the 6 8 and 10 mm diameters respectively critical shear stress values were found to be essentially zero and erodibility values gave erosion indexes that were extremely high the rapid internal erosion resulted in erratic flow and sediment concentrations with periods of no flow as pipes were temporarily clogged followed by surges of high flow and high sediment concentrations tensiometers within 6 cm of the soil pipes did not exhibit pressure increases typically associated with pipe clogging flow through 10 mm diameter soil pipes exhibited tunnel collapse for both soils tested tunnel collapse typically occurred within minutes of flow establishment suggesting that ephemeral gullies could be misinterpreted as being caused by convergent surface flow if observations were made after the runoff event instead of when flow is first established through soil pipes copyright 2011 john wiley sons ltd

factors controlling the distribution of piping in britain a reconnaissance abstract the distribution of piping in britain has been studied from a survey of 74 piped basins and a number of in depth studies at the individual basin scale the survey suggests that nearly 30 of britain is susceptible to piping erosion this is the area covered by soils with histic and vertic properties or with impermeable subsoil horizons lying in upland regions with high annual water balance and steep slopes at an intrabasin scale the intensity of piping shows a broad correspondence with the a s drainage index although there is no fixed relationship and some significant deviations are found inhomogeneities in soil properties and differential exposure to cracking may be the main cause landuse and vegetation cover may also affect distributions however the clearest intrabasin links between pipe distribution and vegetation patterns are found in upland moorland where the pipes are the cause rather than the product of patterns in both soils and vegetation

fluid immiscibility in late alpine gold bearing veins eastern and northwestern european alps gold bearing quartz veins fill late alpine brittle structures in pennine nappes of austria in the tauern window and in northern italy the veins formed in the latter stages of uplift of the alps fluid inclusions in veins sampled from bockstein austria and valle anzasca italy have a wide variety of compositions ranging from aqueous brine about 5 wt nacl equiv to about 50 mol co2 at room temperature the inclusions range with increasing co2 content from two phase aqueous through three phase in which the co2 homogenizes to vapour to three phase with co2 homogenizing to liquid this wide range of inclusion compositions is interpreted as evidence for fluid immiscibility with most inclusions being accidental mixtures of the two end member immiscible fluids the homogenization temperatures of the aqueous inclusions 200 280 c gives the best estimate of temperature of formation of the veins vein formation fluid pressure at bockstein and valle anzasca was about 1 kbar and bockstein veins formed at lower pressure than valle anzasca veins fluid immiscibility may have contributed to deposition of gold at both valle anzasca and bockstein and possibly many other uplift related alpine gold localities

micropiping processes and biancana evolution in southeast tuscany italy abstract biancane badlands consisting of small domes dissected by rills and micropipes with rough disordered microrehef can be found along the apennines in italy the dominant processes forming biancane differ from those of badlands formed on smectite rich mudrocks as micropipes associated with pseudokarstic enlargement of pores and cracks predominate and form the main routes for evacuation of eroded material biancana evolution is controlled by water infiltration into intact bedrock producing an erodible weathering rind which is more porous than intact rock this rind is easily removed by rill or micropipe flow and erosion is therefore weathering controlled depending on rind production by infiltrating water infiltration is initially slow and stepped due to slow water movement through very small capillary pores in intact rock alternating with rapid filling of macropores and cracks this occurs due to rapid matrix pore enlargement by dispersion and or dissolution the infiltration pattern is accurately reproduced by a model built on progressive development of weathering layers by moisture penetration model results are consistent with weathering rind depths and erosion observed in the field and show that a pipe network can be generated on newly exposed rock by the rainfall of one year propagation of the pipe network diverts a progressively larger proportion of runoff into micropipes expanding weathering rind production within the biancana as well as on the surface internal weathering and flow progressively dominate with few unweathered corestones and the biancana gradually collapses into a penultimate souffle like form

loess erosion on the tokaj big hill abstract the erosion of the loess mantle of the tokaj big hill is described on the basis of field observations and surveys as well as laboratory experiments above an altitude of 250 m a 0 5 to 0 7 m thick layer of loess has been removed in the last 100 years below 250 m linear forms of loess erosion are characteristic the most striking among them being gullies and inset roads for a detailed quantitative survey of minor features the 2 hectare area of the terrace system in the rakoczi valley was selected the most common forms were depressions loess wells and loess sinks the laboratory measurements showed that after higher intensity rainfalls sheetwash on the tokaj loess transports twice as many loess grains than is the case with the forest soil and the sheetwash impact of low intensity rain exceeds by almost seven times the value measured on forest soils solution erosion is four or five times more intense underground than on the surface on the solum taken from cultivated loess different values were found k concentration was particularly high compared to loess under natural conditions the anomalies in solution erosion are caused by fertilizers and pesticides the influence of diluted acids on loess structure are presented in electron microscopic photos these experiments provide a means of interpreting the evolution of piping in the rakoczi valley

exploring the frequency size relationships of pipe collapses in different morphoclimatic regions abstract piping is an important land degradation process that occurs in almost all climatic zones this study analyses for the first time the frequency size distribution of different types of pipe collapses pcs sinkholes and compound depressions related to the coalescence of sinkholes compound sinkholes and elongated blind gullies exploring the frequency size relationships of pcs provides critical morphometric information about this hazardous erosion and ground stability process as well as its impact on hillslope denudation hillslope channel coupling and landscape development the analysis has been performed with field based inventories of pcs from five catchments located in two different morphoclimatic environments one in the semi arid ebro depression ne spain valpalmas catchment and four in the humid bieszczady mts se poland in total 724 pcs were mapped among which 335 pcs in valpalmas and 389 pcs in the bieszczady mts the morphometric analyses were based on the major axis the maximum length or width and area of the pcs despite differences between study areas from ne spain and se poland related to climate conditions rainfall regime soil water storage capacity spatial pattern of pipe networks vegetation cover and land use empirical cumulative frequency curves of pcs show similar patterns in all study sites indicating similar overall effects of piping erosion the size distribution of the inventoried pcs can be modelled satisfactorily with logarithmic functions with high goodness of fit values r2 0 93 for each type of pc and the combined set of pcs sinkholes and compound sinkholes blind gullies mapped in each area and in the five catchments together the pcs mapped in valpalmas are displaced towards larger dimensions attributable to local factors the applicability and limitations of frequency size relationships of pcs for geomorphological studies and hazard assessment are discussed

the pb sr nd isotope geochemistry of some recent circum mediterranean granites pb sr and nd isotopic compositions have been analyzed in recent granites from northern africa northern italy and greece lead isotope compositions of k feldspars are rather homogeneous and cluster close to the modern lead of stacey and kramers 1975 but with slightly higher207pb 204pb and208pb 204pb ratios the cyclades samples however have higher206pb 204pb ratios addition of mantle derived lead was probably very limited which supports a quasi closed system evolution of this element in the continental crust the sr nd data fall in the enriched part of the143nd 144nd vs 87sr 86sr diagram and define a smooth hyperbolic mixing curve over a wide area straddling different orogens most granites may be accounted for by a binary mixture between a recycled crustal component and a depleted mantle like component no correlation is observed between either pb and sr or nd isotopic ratios or any isotopic ratio and major element contents quantitative modelling suggests that two cases fit the sr and nd characteristics of these granites they both require anatexis of the crust on a scale large enough to average the isotopic properties of heterogeneous terranes in the first case the mantle derived component may be represented by differentiated island arc type magmas and the granites result from mixing these magmas with anatectic melts in the second case mantle derived igneous rocks such as obducted ophiolites are part of the crustal source and their variable involvement in the anatectic process causes isotopic variations

at the crossroad a new approach to the upper paleolithic art in the western pyrenees abstract the main corridor that has acted as an entrance to the iberian peninsula through the western pyrenees was as an important communication route in western europe during the paleolithic this is an area where despite having documented intense human occupation during different periods of the upper paleolithic the symbolic activity seems incomprehensibly limited compared to other regions such as the cantabrian the northern pyrenees or dordogne the reactivation of research during this last decade when referring to cave art leads to a very different model than the one that had been previously posed for this region mainly due to a series of new discoveries some of which are worth mentioning such as askondo and lumentxa or others of lower interest such as astigarraga praile aitz and aitzbitarte iv the re examination and revision of previously known representations has also contributed to the development of this new model especially thanks to the research carried out in sites such as santimamine altxerri isturitz oxocelhaya sasiziloaga sinhikole or sainte colome as has the revision of the great amount of portable art mainly from isturitz as well as the discovery of new objects from antolina ekain praile aitz aitzbitarte iii santa catalina arlanpe and bourrouilla due to these advances the image that we have of the artistic activity around the epicentre that was the gulf of biscay has substantially varied in a way that allows us to carry out a more detailed approximation to a series of relevant questions such as the chronology of the artistic representations the variability of their contexts the technical and formal relations among different neighbouring regions and their relation to the non symbolic archaeological record

modelling fractionation of stable isotopes in stalagmites abstract high resolution 13c and 18o profiles recorded in precisely dated speleothems are widely used proxies for the climate of the past both 13c and 18o depend on several climate related effects including meteorological processes processes occurring in the soil zone above the cave and isotope fractionation processes occurring in the solution layer on the stalagmite surface here we model the latter using a stalagmite isotope and growth model and determine the relationship between the stable isotope values in speleothem calcite and cave parameters such as temperature drip interval water p co 2 and a mixing coefficient describing mixing processes between the solution layer and the impinging drop the evolution of 13c values is modelled as a rayleigh distillation process and shows a pronounced dependence on the residence time of the solution on the stalagmite surface and the drip interval respectively the evolution of 18o values in contrast is also influenced by buffering reactions between the bicarbonate in the solution and the drip water driving the 18o value of the bicarbonate towards the value expected for equilibrium isotope fractionation between drip water and calcite this attenuates the dependence of the 18o values on drip interval the temperature dependence of 18o however is more pronounced than for 13c and in a similar range as expected for fractionation under equilibrium conditions we also investigate the isotopic enrichment of the 13c and 18o values along individual growth layers and thus the slopes expected for hendy tests the results show that a positive hendy test is only possible if isotope fractionation occurred under disequilibrium conditions however a negative hendy test does not exclude that isotope fractionation occurred under disequilibrium conditions a more reliable indicator for disequilibrium fractionation is the enrichment of the 13c values along an individual growth layer

importance of slope gradient and contributing area for optimal prediction of the initiation and trajectory of ephemeral gullies abstract ephemeral gully erosion rates are controlled by various factors out of which topography plays an important role this study investigates the possibility to predict the location of ephemeral gullies using two topographic attributes only i e local slope gradient s and upslope contributing area per unit length of contour a s an inverse relationship between s and a s in which the relative importance of the area exponent was varied was evaluated as to its performance in predicting the location of ephemeral gullies for three intensively cultivated catchments in the belgian loess belt this model is easily applicable as it only uses information on topography which can be derived from a digital elevation model and land use predicted locations of ephemeral gullies were confronted with the locations recorded over 5 years of field observations for all catchments a high relative area exponent relative to the slope exponent was required to yield good results the optimal relative area exponent ranged from 0 7 to 1 5 however the quality of the prediction did not vary significantly when changing the exponent within this range an average relative area exponent of ca 1 is appropriate for all three study areas and may therefore be proposed for similar areas under similar conditions a striking discrepancy was found between the high relative area exponent required to predict optimally the trajectory of the gullies and the low relative area exponent 0 2 required to identify the spots in the landscape where ephemeral gullies begin this indicates that spots in the landscape where gullies start are more controlled by slope gradient while the presence of concavities control the trajectory of the gullies until the slope gradient is too low and sediment deposition starts no relationship was found between the frequency of the occurrence of ephemeral gullies and the percentage of predicted gully pixels for each frequency class this indicates that frequently occurring gullies at the same location are not easier to predict than accidental gullies

characterization of macropore structure of malan loess in nw china based on 3d pipe models constructed by using computed tomography technology abstract malan loess is a grayish yellow or brownish yellow clastic highly porous and brittle late quaternary sediment formed by the accumulation of windblown dust the present day pore structure of malan loess is crucial for understanding the loessification process in history loess strengths and mechanical behavior this study employed a modern computed tomography ct device to scan malan loess samples which were obtained from the east part of the loess plateau of china a sophisticated and efficient workflow for processing the ct images and constructing 3d pore models was established by selecting and programming relevant mathematical algorithms in matlab such as the maximum entropy method medial axis method and node recognition algorithm individual pipes within the malan loess were identified and constructed by partitioning and recombining links in the 3d pore model the macropore structure of malan loess was then depicted using quantitative parameters the parameters derived from 2d images of ct scanning included equivalent radius length and aspect ratio of pores porosity and pore distribution entropy whereas those derived from the constructed 3d structure models included porosity coordination number node density pipe radius length length density dip angle and dip direction the analysis of these parameters revealed that malan loess is a strongly anisotropic geomaterial with a dense and complex network of pores and pipes the pores discovered on horizontal images perpendicular to the vertical direction were round and relatively uniform in shape and size and evenly distributed whereas the pores discovered on vertical images varied in shape and size and were distributed in clusters the pores showed good connectivity in vertical direction and formed vertically aligned pipes but displayed weak connectivity in horizontal directions the pipes in vertical direction were thick long and straight compared with those in horizontal directions these results were in good agreement with both numerical simulation and laboratory permeability tests which indicate that malan loess is more permeable in the vertical direction than in the horizontal directions

agricultural land degradation by piping erosion in chaco plain northwestern argentina abstract soil piping has been pointed out as an important water erosion agent in a wide range of climatic regions it is responsible for high soil losses in loess derived soils the goal of this study is to evaluate the factors that are acting in the generation of piping processes and explain the mechanism of pipe collapse initiation the study was carried out in loess derived soils located in a rural area of the chaco plain between tucuman and santiago del estero provinces in northwestern argentina pipe collapse types were described and soil loss estimation was performed factors influencing the process were studied under six different categories i e physico chemical and soil mechanical soil mineralogical microstructural biological and land use properties in the study area pipes took place in agricultural fields principally in pastures with slope gradients between 1 and 3 soil pipe collapse occurred in the area as a consequence of sudden wetting of the collapsible soils during summer storms pipe collapse forms vertical pipes or macropores that provide pathways for runoff directly into the soil pipe network in addition tension cracks adjacent to pipe collapses can provide pathways for preferential flow from the surface to the soil pipe network with successive water infiltration the size of the pipes tends to increase and evolves to advanced stages of the process by internal erosion and eventually more pipe collapse blind gully formation is the final step of the piping process after the pipes roof collapse

characteristics of the size distribution of recent and historical landslides in a populated hilly region despitetheavailabilityofstudiesonthefrequencydensityoflandslideareasinmountainousregions frequency areadistributions of historical landslide inventories in populated hilly regions are absent this study revealed that the frequency area distribution derived from a detailed landslide inventory of the flemish ardennes belgium is significantly different from distributions usually obtainedinmountainousareaswherelandslidesaretriggeredbylarge scalenaturalcausalfactorssuchasrainfall earthquakesorrapid snowmelt instead the landslide inventory consists of the superposition of two populations i e i small b1 2 10 2 km 2 shallow complexearthslides that areat most30yrold and ii large n1 2 10 2 km 2 deep seatedlandslides that areolder than100yr both subpopulations are best represented by a negative power law relation with exponents of 0 58 and 2 31 respectively this study focused on the negative power law relation obtained for recent small landslides and contributes to the understanding of frequency distributions of landslide areas by presenting a conceptual model explaining this negative power law relation for small landslides in populatedhilly regions according to the model hilly regions canberelatively stable under the present dayenvironmental conditions andlandslidesaremainlytriggeredbyhumanactivitiesthathaveonlyalocalimpactonslopestability therefore landslidescausedby anthropogenic triggers are limited in size and the number of landslides decreases with landslide area the frequency density of landslide areas for old landslides is similar to those obtained for historical inventories compiled in mountainous areas as apart from the negative power law relation with exponent 2 31 for large landslides a positive power law relation followed by a rollover is observed for smaller landslides however when analysing the old landslides together with the more recent ones the present day higher temporal frequency of small landslides compared to large landslides obscures the positive power law relation and rollover 2007 elsevier b v all rights reserved

tunnel erosion and sediment production in the hilly loess region north china in this study detailed monitoring of water and sediment delivery from major tunnel systems was conducted in a small semi arid sub basin locally known as yangdaogou in the hilly loess region north china these deep seated tunnels are located as much as 30 m below the slope surface in deep quaternary loess formations in the yangdaogou these systems have large amphitheatre like inlets with mean diameter and depth of 4 8 and 4 99 m respectively these dimensions represent some of the largest tunnel inlets in the world during 1989 and 1990 fifteen rainstorms were monitored at six tunnel outlets due to practical difficulties only 35 sets of tunnel storm data were obtained observed sediment concentration of tunnel flows ranges from 8 2 to 893 2 g l the peak sediment concentrations in tunnel flows are not distinctively higher than those in channel flows but considerably higher than those measured from untunneled sideslopes no significant correlations between runoff and sediment yield can be found in most tunnels at both within and between storm levels such an erratic relationship is ascribed to the rapid shift of runoff and sediment source area the occurrence of collapses within tunnels and the initiation of new tunnel inlets based on the field monitored data 57 of basin sediment production is delivered by the tunnel systems suggesting that tunnel erosion is a major erosion process in the hilly loess region

soil pipe collapses in a loess pasture of goodwin creek watershed mississippi role of soil properties and past land use little is known about the association of soil pipe collapse features with soil properties or land use history three loess covered catchments in northern mississippi usa were characterized to investigate these relationships soil pipe collapses were characterized for their size type feature and spatial location along with soil properties across the three catchments although mapped as the same soil one of the catchments did not contain pipe collapse features while the other two had 29 4 and 15 4 pipe collapses per hectare these loess soils contained fragipan layers that are suspected of perching water thereby initiating the piping processes pipe collapses associated with subsurface flow paths were not always consistent with surface topography the surface layer tended to be non erodible while layers below even the upper fragipan layers were susceptible to erosion by pipeflow soil properties of the lowest fragipan layer were highly variable but tended to prevent further downward erosion of soil pipes and thus formed a lower boundary for gullies middle to lower landscape positions in one of the piped catchments contained anthropic soils that were highly erodible these anthropic soils were previously gullies that were filled in in the 1950s when forested areas assumed to have been established when land was previously converted from crop to forest land were converted to pasture three decades after this land use change from forest to pasture pipe collapses became evident in contrast the adjacent catchment that does not exhibit pipe collapse features experienced severe sheet and rill erosion prior to the 1930s while in cotton production the surface horizons above the lower fragipan layer were completely removed during this period thus the top soil layer that tends to form a bridge above soil pipes in the more erodible subsoil layers was removed this study showed that knowledge of soil characteristics or topography alone do not explain the distribution of soil pipe collapses as past land use can play a definitive role copyright 2015 john wiley sons ltd

fluid inclusion studies on the gold deposits of the upper anzasca valley northwestern alps italy the gold deposits of the upper anzasca valley are part of the monte rosa gold district northwestern alps italy the mineralization occurs within polymetamorphic paleozoic metasedimentary and metagranitic rocks of the pennidic monte rosa unit the orebodies consist of more or less concordant veins where they are hosted by metasedimentary rocks whereas in the metagranites they occupy fractures and shear zones discordant with the foliation field evidence suggests however a common late alpine age for the emplacement of both types of orebodies the mineralogy of the orebodies is dominated by quartz gold is invariably associated with sulfides pyrite arsenopyrite galena sphalerite chalcopyrite and sulfosalts the characteristics of fluid inclusions in quartz from gold bearing veins are remarkably consistent the inclusions are moderately saline brines containing at room temperature about 20 to 60 percent vol of a low density rather pure co 2 phase they were probably homogeneous at the time of trapping small amounts of ch 4 occur in some inclusions total homogenization occurs either in the liquid or in the gas phase or by near critical phenomena at temperatures mostly on the order of 300 degrees to 350 degrees c by combining these temperatures with geologic pressure estimates and with temperatures inferred from arsenopyrite compositions trapping conditions of about 400 degrees to 450 degrees c at pressures of 1 to 1 5 kbars are derived a less common presumably later type of co 2 poor inclusion is interpreted as a late influx of cooler and less saline fluids quartz from barren veins also contains co 2 bearing inclusions however these show higher t sub m clathrate lower t sub h sub co 2 and lower total homogenization temperatures than mineralized veins results of reconnaissance studies on fluid inclusions from other gold deposits val sesia val toppa in the monte rosa district are somewhat different from those of the upper anzasca valley the co 2 phase is of higher density and total homogenization temperatures are lower combined with field evidence and available pb and o isotope data the fluid inclusion characteristics are consistent with a model of ore genesis in which the gold deposits of the upper anzasca valley were formed in the late stages of the alpine orogeny by presumably metamorphic fluids probably produced by devolatilization of deep unexposed portions of monte rosa crustal rocks the strict association of gold with sulfides suggests that gold possibly was transported as thio complexes possible precipitation mechanisms include cooling dilution minor wall rock reaction and decrease of sulfur activity in the fluid similar processes probably were active in the formation of other neighboring gold deposits but there is evidence that gold deposition on a regional scale was related to at least two distinct hydrothermal systems separate in space and also in time

a new aurignacian engraving from abri blanchard france implications for understanding aurignacian graphic expression in western and central europe abstract in the excitement of the widely publicized new finds of aurignacian art from chauvet from the swabian jura and from as far afield as pestera coliboaia in romania it has almost been forgotten that a rich corpus of aurignacian wall painting engraving and bas relief sculpture had been recognized and studied before world war i in the vezere valley of sw france scientific knowledge of the chronological and cultural context of that early discovered graphic record has been limited by the crude archaeological methods of that pioneering era and the loss and dispersal of many of the works discovered in 2011 we launched new excavations and a re analysis of one of the key sites for such early discoveries the collapsed rock shelter of abri blanchard in 2012 we discovered in situ a limestone slab engraved with a complex composition combining an aurochs and dozens of aligned punctuations this new find recovered by modern methods and dated by molecular filtration and hydroxyproline 14c provides new information on the context and dating of aurignacian graphic imagery in sw france and its relationship to that of other regions the support is not a fragment of collapsed shelter ceiling and is situated in the midst of quotidian occupational debris the image shows significant technical and thematic similarities to chauvet that are reinforced by our reanalysis of engraved slabs from the older excavations at blanchard the aligned punctuations find their counterparts at chauvet in the south german sites and on several other objects from blanchard and surrounding aurignacian sites in sum we argue that dispersing aurignacian groups show a broad commonality in graphic expression against which a certain number of more regionalized characteristics stand out a pattern that fits well with social geography models that focus on the material construction of identity at regional group and individual levels

the value of a physically based model versus an empirical approach in the prediction of ephemeral gully erosion for loess derived soils abstract a data set on soil losses and controlling factors for 58 ephemeral gullies has been collected in the belgian loess belt from march 1997 to march 1999 of the observed ephemeral gullies 32 developed at the end of winter or in early spring winter gullies and 26 ephemeral gullies developed during summer summer gullies the assessed data have been used to test the physically based ephemeral gully erosion model egem and to compare its performance with the value of simple topographical and morphological indices in the prediction of ephemeral gully erosion analysis shows that egem is not capable of predicting ephemeral gully cross sections well although conditions for input parameter assessment were ideal some parameters such as channel erodibility critical flow shear stress and local rainfall depth showed great uncertainty rather than revealing egem s inability of predicting ephemeral gully erosion this analysis stresses the problematic nature of physically based models since they often require input parameters that are not available or can hardly be obtained with respect to the value of simple topographical and morphological indices in predicting ephemeral gully erosion this study shows that for winter gullies and summer gullies respectively over 80 and about 75 of the variation in ephemeral gully volume can be explained when ephemeral gully length is known moreover when previously collected data for ephemeral gullies in two mediterranean study areas and the data for summer gullies formed in the belgian loess belt are pooled it appears that one single length l volume v relation exists v 0 048 l 1 29 r 2 0 91 these findings imply that predicting ephemeral gully length is a valuable alternative for the prediction of ephemeral gully volume a simple procedure to predict ephemeral gully length based on topographical thresholds is presented here secondly the empirical length volume relation can also be used to convert ephemeral gully length data extracted from aerial photos into ephemeral gully volumes

sediment detachment and transport processes associated with internal erosion of soil pipes subsurface flow can be an important process in gully erosion through its impact on decreasing soil cohesion and erosion resistance as soil water content or pressure increases and more directly by the effects of seepage forces on particle detachment and piping the development of perched water tables in duplex soils fosters lateral flow that can result in seepage at the surface of hillslopes and or formation of soil pipes by internal erosion of lateral preferential flow paths continued internal erosion of soil pipes can lead to gullies dam and levee failures however the processes involved in particle and aggregate detachment from soil pipe walls and transport processes within soil pipes have not been well studied or documented this paper reviews the limited research on sediment detachment and transport in macropores and soil pipes and applies the knowledge learned from the much more extensive studies conducted on streams and industrial pipes to hydrogeologic conditions of soil pipes knowledge gaps are identified and recommendations are made for future research on sediment detachment and transport in soil pipes

characteristics and controlling factors of bank gullies in two semi arid mediterranean environments abstract bank gullies are gullies that are formed due to a height drop caused by a terrace or a river bank which develop by headward retreat in erodible hillslopes this study aims i to investigate the morphology of actively eroding bank gullies i e geometrical characteristics resulting from past erosion and active erosion processes shaping the gully and ii to find relationships with environmental site characteristics such as topographical parameters material properties and climate the ultimate goal is to identify the most important controlling factors of past and present bank gully erosion fifty five active bank gullies formed in different lithologies by various erosion processes have been selected in the guadalentin basin and the surroundings of guadix southeast spain for each bank gully site geometrical and topographical parameters of both the channel and the drainage basin were measured erosion features indicating activity at the gully head such as tension cracks plunge pools undercutting fluting piping and rill or sheet erosion on sloping side walls were mapped and samples were taken from distinct lithological layers that were considered to influence the type and intensity of erosion processes a relationship could be shown between the presence of piping and fluting and a number of material characteristics including particle size distribution dispersion behaviour and electrical conductivity on the other hand lithology appeared not to be a differentiating factor on gully development in the long run as expressed by the total eroded volume v this parameter was most strongly related to the drainage basin area in which the entire bank gully had been formed a o explaining 66 of the variance the relationship is v 1 75 a o 0 59 no significant difference was found between regression lines through sub datasets of different soil textural classes finally multiple regression was used to include both topographical parameters and material characteristics in an explanatory and or predictive equation for the total eroded bank gully volume the results of the analyses using the entire dataset including the sites in the guadalentin as well as in the guadix area have been compared with the results for the separate study areas differences are not only related to topographical and lithological characteristics but may also be the consequence of a different climate in the two areas

chronology of western pyrenean paleolithic cave art a critical examination abstract the last two decades have witnessed considerable advances in chronometric approaches to cave art specifically with the application of new dating techniques ams 14c u series thermoluminescence in this paper we assess all the currently available chronological information numerical dates stylistic comparisons between portable and cave art the immediate context of art and its relationship with archaeological strata and wider artistic styles pertaining to cave art of the western pyrenean and eastern cantabrian regions in order to summarize the evolution of art in this important area the data allow only an imprecise definition of a broad chronological framework for the area of study at present we cannot define precisely the origins of figurative cave art in the area the earliest pre magdalenian cycle is characterized by basic figures in which frequently only the outline is represented by contrast in the later magdalenian cycle the figures are naturalistic and realistically composed the critical analysis of available chronological information is necessary in order for us to advance towards the construction of more solid and less subjective frameworks for the development of art

prediction of spatial patterns of collapsed pipes in loess derived soils in a temperate humid climate using logistic regression abstract soil piping tunnel erosion has been recognised as an important erosion process in collapsible loess derived soils of temperate humid climates which can cause collapse of the topsoil and formation of discontinuous gullies information about the spatial patterns of collapsed pipes and regional models describing these patterns is still limited therefore this study aims at better understanding the factors controlling the spatial distribution and predicting pipe collapse a dataset with parcels suffering from collapsed pipes n 560 and parcels without collapsed pipes was obtained through a regional survey in a 236 km study area in the flemish ardennes belgium logistic regression was applied to find the best model describing the relationship between the presence absence of a collapsed pipe and a set of independent explanatory variables i e slope gradient drainage area distance to thalweg curvature aspect soil type and lithology special attention was paid to the selection procedure of the grid cells without collapsed pipes apart from the first piping susceptibility map created by logistic regression modelling a second map was made based on topographical thresholds of slope gradient and upslope drainage area the logistic regression model allowed identification of the most important factors controlling pipe collapse pipes are much more likely to occur when a topographical threshold depending on both slope gradient and upslope area is exceeded in zones with a sufficient water supply due to topographical convergence and or the presence of a clay rich lithology on the other hand the use of slope area thresholds only results in reasonable predictions of piping susceptibility with minimum information

a chemical model for the concentration of gold in volcanogenic massive sulphide deposits abstract study and review of the gold distribution in selected volcanogenic massive sulphide deposits rosebery and hellyer in tasmania mt chalmers in queensland and millenbach in quebec indicates that gold has two distinct occurrences in these deposits 1 a gold zinc lead silver association which is commonly found in the upper part of zinc rich massive sulphide lenses e g rosebery and hellyer and 2 a gold copper association which is commonly present in the stringers and lower portions of copper rich deposits e g mt chalmers and millenbach in each deposit one of these occurrence dominates almost to the exclusion of the other thermodynamic modelling of the volcanogenic fluid which is based on previous work by large 1977 eldridge et al 1983 and pisutha arnond and ohmoto 1983 indicates that gold in the upper part of the zinc rich massive sulphide lenses was transported as au hs 2 while gold in the stringers and bases of copper rich massive sulphide deposits was transported as aucl 2 the ph and o 2 of the ore forming fluid have an important control on gold deposition and therefore gold grades high gold grades in zinc rich massive sulphide are promoted by near neutral oxidised and low temperature 150 c to 275 c fluids as indicated by the presence of barite carbonate feldspar gangue high gold grades in the copper rich stringers and base of the massive sulphide are promoted by higher temperatures 275 c to 350 c relatively oxidised fluids as indicated by bornite or by barite or hematite gangue and relatively acid fluids as indicated by kaolinite gangue in o 2 t space significant gold transport by au hs 2 occurs only in the pyrite stability field at relatively low temperatures 2 is not restricted by iron mineral equilibria but is greatest in the hematite magnetite and pyrite fields at high temperatures 300 c and high o 2 10 30 under conditions of au hs 2 transport bonanza type gold deposition may be found in areas where the hydrothermal fluids passed from the field of pyrite stability to that of hematite stability oxidation of hydrothermal fluids by seawater mixing and the rapid precipitation of sulphide minerals at the top of the massive sulphide lens may cause the precipitation of gold via the mechanisms of either h 2 s oxidation or sulphide gold coprecipitation other types of gold deposits may be classified into either the gold zinc or gold copper association the gold copper bismuth association is developed in higher temperature systems of moderate to high salinity where aucl 2 is the dominant complex e g porphyry cu au deposits and au rich skarns whereas the gold zinc lead silver association is developed in systems of low salinity and high h 2 s where au hs 2 is the dominant complex e g epithermal au ag and archean greenstone hosted au quartz

does the topographic threshold concept explain the initiation points of sunken lanes in the european loess belt abstract sunken lanes or road gullies are a common geomorphic feature in the european loess belt these landforms are usually created by various processes over time water erosion mass movements and traffic they are important for ecology and biodiversity for recreation and transport as well as from a hydrological and geomorphological perspective e g by enhancing the runoff and sediment connectivity of the landscape nonetheless little is known about their origin and evolution the formation of sunken lanes is typically only understood in qualitative terms while no studies so far have provided a quantitative analysis of their initiation conditions to address this research gap and to improve our geomorphic understanding of this landform we investigated to what extent sunken lanes can be treated and described as a gully erosion process more specifically we explored to what extent their position in the landscape and their characteristics can be explained by the topographic slope area sa threshold that typically controls gully initiation s k a b with k and b empirical constants based on field surveys and lidar data analyses we determined the slope gradient of the soil surface s and contributing area a for 132 representative sunken lane heads in the belgian loess belt and collected data on several other characteristics position of initiation and sedimentation points width depth and length of each sunken lane our results show a very large scatter on the s and a values moreover the morphological characteristics of sunken lanes e g width and length showed no clear relation with these values however a very weak sa threshold relation with a low b exponent 0 016 and a low k coefficient 0 022 could be identified overall our results show that the formation of sunken lanes is not in line with the topographic threshold conditions that govern the initiation of gullies across different environments the low k coefficient and the lack of a strong correlation between initiation slope and contributing area point towards an overall higher susceptibility to the formation of sunken lanes than the formation of gullies this supports the conclusion that not only concentrated flow detachment and transport but especially human activities mainly traffic erosion play a major role in the initiation and development of sunken lanes

road surface drainage channel initiation and slope instability field surveys of road drainage concentration at three sites in the western united states are used to test simple models relating channel initiation and shallow landsliding to ground slope and contributing area thresholds the form of boundaries between data for locations where road drainage concentration is associated with either shallow landsliding channel initiation by overland flow or no observable geomorphic effect is consistent with theoretically derived drainage area slope relations comparison of survey data with results of previous studies in these areas indicates that the drainage area required to support a channel head is smaller for road related runoff than for undisturbed slopes contrary to current land management paradigms in the pacific northwest drainage concentration from ridgetop roads may cause both landsliding and integration of the channel and road networks road drainage concentration increases the effective length of the channel network and strongly influences the distribution of erosional processes in each of the study areas the approach of using field reconnaissance to establish thresholds for erosion associated with road drainage provides a useful method to define regional criteria for road design that should reduce impacts on downstream channel systems

monitoring channel head erosion processes in response to an artificially induced abrupt base level change using time lapse photography abstract gullies that terminate at a vertical wall are ubiquitous throughout arid and semiarid regions multi year assessments of gully evolution and headcut advance are typically accomplished using traditional ground surveys and aerial photographs with much recent research focused on integrating data collected at very high spatial resolutions using new techniques such as aerial surveys with blimps or kites and ground surveys with lidar scanners however knowledge of specific processes that drive headcut advance is limited due to inadequate observation and documentation of flash floods and subsequent erosion that can occur at temporal resolutions not captured through repeat surveys this paper presents a method for using very high temporal resolution ground based time lapse photography to capture short duration flash floods and gully head evolution in response in 2004 a base level controlling concrete weir was removed from the outlet of a 1 29 ha semiarid headwater drainage on the walnut gulch experimental watershed in southeastern arizona usa during the ten year period from 2004 to 2014 the headcut migrated upchannel a total of 14 5 m reducing the contributing area at the headwall by 9 5 beginning in july 2012 time lapse photography was employed to observe event scale channel evolution dynamics the most frequent erosion processes observed during three seasons of time lapse photography were plunge pool erosion and mass wasting through sidewall or channel headwall slumping that occurred during summer months geomorphic change during the ten year period was dominated by a single piping event in august 2014 that advanced the channel head 7 4 m 51 of the overall advance and removed 11 3 m 3 of sediment high temporal resolution time lapse photography was critical for identifying subsurface erosion processes in the absence of time lapse images piping would not have been identified as an erosion mechanism responsible for advancing the gully headwall at this site

the coupled δ13c radiocarbon systematics of three late glacial early holocene speleothems insights into soil and cave processes at climatic transitions abstract the coupled 13 c radiocarbon systematics of three european stalagmites deposited during the late glacial and early holocene were investigated to understand better how the carbon isotope systematics of speleothems respond to climate transitions the emphasis is on understanding how speleothems may record climate driven changes in the proportions of biogenic soil carbon and limestone bedrock derived carbon at two of the three sites the combined 13 c and 14 c data argue against greater inputs of limestone carbon as the sole cause of the observed shift to higher 13 c during the cold younger dryas in these stalagmites gar 01 from la garma cave n spain and so 1 from sofular cave turkey the combined changes in 13 c and initial 14 c activities suggest enhanced decomposition of old stored more recalcitrant soil carbon at the onset of the warmer early holocene alternative explanations involving gradual temporal changes between open and closed system behaviour during the late glacial are difficult to reconcile with observed changes in speleothem 13 c and the growth rates in contrast a stalagmite from pindal cave n spain indicates an abrupt change in carbon inputs linked to local hydrological and disequilibrium isotope fractionation effects rather than climate change for the first time it is shown that while the initial 14 c activities of all three stalagmites broadly follow the contemporaneous atmospheric 14 c trends the younger dryas atmospheric 14 c anomaly can be clearly discerned subtle changes in speleothem initial 14 c activities are linked to climate driven changes in soil carbon turnover at a climate transition

regional mapping and characterisation of old landslides in hilly regions using lidar based imagery in southern flanders abstract analysis of lidar derived imagery led to the discovery of more than 330 pre holocene to recent landslides in southern flanders 4850 km 2 the morphology of three landslides including the 266 5 ha deep seated gravitational slope deformation in alden biesen was investigated in more detail the analysis of the morphological and topographical characteristics width length relation frequency area distribution and topographical threshold of the landslides revealed important differences compared to the characteristics reported in other landslide studies and helped understanding possible landslide triggering mechanisms especially the possibility of a seismic origin of the landslides was investigated finally a heuristic model for region wide landslide susceptibility mapping was successfully tested the susceptibility model and map allow prediction of future landslide locations and contribute to better understanding the role of individual causal factors on landslide location and spatial density the results suggest that landslides on low gradient soil mantled hills are a more important contributor to landscape evolution of hilly areas than was hitherto thought the morphology of all hilly regions of flanders is clearly marked by landslide processes and higher landslide densities often coincide with the presence of quaternary active faults this study further shows that high resolution topographical data such as lidar significantly contributes to a better detection of old previously unknown landslides

factors controlling the spatial distribution of soil piping erosion on loess derived soils a case study from central belgium abstract collapsible loess derived soils are prone to soil piping erosion where enlargement of macropores may lead to a subsurface pipe network and eventually to soil collapse and gully development this study aims at understanding the main factors controlling spatial patterns of piping in loess derived soils under a temperate climate to map the spatial distribution of piping and identify the environmental controls on its distribution a regional survey was carried out in a 236 km2 study area in the flemish ardennes belgium orthophotos taken at optimal field conditions winter were analyzed to detect piping in open landscapes and ground thruthing was systematically done through field surveys in total 137 parcels having 560 collapsed pipes were mapped dimensions of the sinkholes and local slope gradient were measured in the field and topographical variables were derived from lidar data land use plays an important role as 97 of the sites with piping are found under pasture the probability of piping increases rapidly on hillslopes with gradients exceeding 8 and with a concave profile and plan curvature enhancing subsurface flow concentration the zones with soil profiles on shallow loess over a relatively thin layer of homogeneous blue massive clays aalbeke member are most prone to piping soil characteristics are of less importance to explain piping occurrence furthermore the topographical threshold line indicating the critical slope gradient for a given contributing drainage area was determined this threshold line negative power relation is similar to the threshold line for shallow gully initiation

impact of wind on the spatial distribution of rain over micro scale topography numerical modelling and experimental verification the wind driven rain effect refers to the redistribution of rainfall over micro scale topography due to the existence of local perturbed wind flow patterns rainfall measurements reported in the literature point to the fact that the wind driven rain distribution can show large variations over micro scale topography these variations should be taken into account in hillslope hydrology in runoff and erosion studies and in the design of rainfall monitoring networks in practice measurements are often not suitable for determining the wind driven rain distribution therefore a few researchers have employed numerical modelling in order to provide confidence in using numerical models experimental verification for a range of different topographic features is imperative the objective of this study is to investigate the adequacy of a two dimensional computational fluid dynamics cfd model to predict the wind driven rain distribution over small scale topography the numerical model is applied to a number of topographic features including a succession of cliffs a small isolated hill a small valley and a field with ridges and furrows the numerical results are compared with the corresponding measurement results reported in the literature it is shown that two dimensional numerical modelling can provide a good indication of the wind driven rain distribution over each type of micro scale topography that is considered in this study it is concluded that more detailed verification procedures are currently inhibited due to the lack of available and detailed spatial and temporal rainfall data from field measurements copyright 2005 john wiley sons ltd

discussion by blanca ochoa and marcos garcia diez in a recent paper by ochoa and garcia diez 2013 the available evidences for a chronology of western pyrenean paleolithic cave art are critically analyzed and discussed and an alternative chronological organization is proposed on the basis of stylistic comparison in this paper we discuss the critics made to the immediate context dating proposals in altxerri b askondo and etxeberri by giving the detailed information that has been recently published garate and rios garaizar 2012 garate et al 2012 gonzalez sainz et al 2013 we also discuss the validity of the stylistic comparisons proposed by ochoa and garcia diez 2013 for the gravettian and the magdalenian art finally we discuss the problems for establishing a reliable chronological framework for paleolithic rock art in this area

the effectiveness of hillshade maps and expert knowledge in mapping old deep seated landslides large deep seated landslides with a shear surface deeper than 3 m and a mean affected area of 4 2 ha are common features in the flemish ardennes none of these deep seated landslides are dated but they are assumed to be rather old 100 years because most of these landslides are located under forest aerial photo interpretation commonly used for the creation of landslide inventories is not a suitable tool to map the landslides in the flemish ardennes therefore an intensive 100 day field survey was carried out by two geomorphologists in a 430 km 2 study area this resulted in a landslide inventory map indicating the location of 135 large deep seated landslides but field surveys are time consuming and thus very expensive therefore a cheaper and faster mapping technique was tested a hillshade map was constructed for the study area in a gis idris132 from a 5 m resolution digital elevation model dem seven experts were given 1 h to indicate all the hillslope sections which they suspected to be possible landslides on a copy of the aforementioned map scale 1 100 000 in total this exercise took only 1 day i e 7 person hours large differences in the number of presumed landslides and the extent of the hillslopes thought to be affected by landslides were reported among the seven experts the polygon and pixel efficiency were introduced to estimate the quality of the landslide maps based on hillshade maps and expert knowledge compared to the field survey based landslide inventory the quality of the landslide inventories based on the hillshade maps and expert knowledge was relatively low experts familiar with the study area obtained somewhat better results than experts who visited the study area only once a combination of the seven expert maps did not result in a good inventory map because too many unaffected hillslopes were incorrectly indicated as affected by landslides the results obtained in this study are comparable to an investigation carried out by wills c j mccrink t p 2002 comparing landslide inventories the map depends on the method environmental and engineering geoscience 8 279 293 although the tested method can never replace a detailed field survey taking into account the proposed improvements it can be used for the creation of a regional inventory map of old landslides in a densely forested area where light detection and ranging lidar data are unavailable c 2004 elsevier b v all rights reserved

assessment of grass root effects on soil piping in sandy soils using the pinhole test abstract soil piping is an important land degradation process that occurs in a wide range of environments despite an increasing number of studies on this type of subsurface erosion the impact of vegetation on piping erosion is still unclear it can be hypothesized that vegetation and in particular plant roots may reduce piping susceptibility of soils because roots of vegetation also control concentrated flow erosion rates or shallow mass movements therefore this paper aims to assess the impact of grass roots on piping erosion susceptibility of a sandy soil the pinhole test was used as it provides quantitative data on pipeflow discharge sediment concentration and sediment discharge tests were conducted at different hydraulic heads i e 50 mm 180 mm 380 mm and 1020 mm results showed that the hydraulic head was positively correlated with pipeflow discharge sediment concentration and sediment discharge while the presence of grass roots expressed as root density was negatively correlated with these pipeflow characteristics smaller sediment concentrations and sediment discharges were observed in root permeated samples compared to root free samples when root density exceeds 0 5 kg m 3 piping erosion rates decreased by 50 compared to root free soil samples moreover if grass roots are present the positive correlation between hydraulic head and both sediment discharge and sediment concentration is less pronounced demonstrating that grass roots become more effective in reducing piping erosion rates at larger hydraulic heads overall this study demonstrates that grass roots are quite efficient in reducing piping erosion rates in sandy soils even at high hydraulic head 1 m as such grass roots may therefore be used to efficiently control piping erosion rates in topsoils

soil loss rates due to piping erosion compared with surface soil erosion by water subsurface erosion piping is generally less studied and harder to quantify however wherever piping occurs it is often a significant or even the main sediment source in this study the significance of soil loss due to piping is demonstrated through an estimation of soil volume lost from pipes and pipe collapses n 560 in 137 parcels under pasture on loess derived soils in a temperate humid climate belgium assuming a period of 5 to 10 years for pipe collapse to occur mean soil loss rates of 2 3 and 4 6 t ha 1 yr 1 are obtained which are at least one order of magnitude higher than surface erosion rates 0 01 0 29 t ha 1 yr 1 by sheet and rill erosion under a similar land use the results obtained for the study area in the flemish ardennes correspond well to other measurements in temperate environments they are however considerably smaller than soil loss rates due to subsurface erosion in semi arid environments although local slope gradient and drainage area largely control the location of collapsed pipes in the study area these topographic parameters do not explain differences in eroded volumes by piping hence incorporation of subsurface erosion in erosion models is not straightforward copyright 2011 john wiley sons ltd

controls on the spatial distribution of natural pipe outlets in heavily degraded blanket peat abstract natural soil pipes are recognised as a common geomorphological feature in many peatlands and they can discharge large quantities of water and sediment however little is known about their morphological characteristics in heavily degraded peat systems this paper presents a survey of pipe outlets in which the frequency and extent of natural soil pipes are measured across a heavily gullied blanket peat catchment in the peak district of northern england over a stream length of 7 71 km we determined the occurrence and size of 346 pipe outlets and found a mean frequency of 22 8 km 1 gully bank topographic position was an important control on the size and depth of pipe outlets aspect had a large influence on pipe outlet frequency with southwest and west facing gully banks hosting more than 43 of identified pipe outlets pipe outlets on streambanks with signs of headward retreat were significantly larger and closer to the peat surface compared to pipe outlets that issued onto uniform streambank edges we suggest that larger pipe frequencies are observed on gully banks that are more susceptible to desiccation cracking and propose that future peatland restoration works could prioritise mitigating against pipe formation by revegetating and reprofiling south and west facing gully banks

closed depressions in the european loess belt natural or anthropogenic origin abstract closed depressions cds are typical geomorphological features of the loess belt in europe cds have been reported in several regions of the european loess belt where they are described as hollows mardeles wymoki crovuri bludtsa and zapadiny the natural and anthropogenic origins of cds are debated in literature moreover no comprehensive review of the geomorphic properties or the evolution of these depressions exists therefore this paper reviews the characteristics of cds in the european loess belt and attempts to better understand their genesis based on detailed case studies the main morphometric features as well as sediment deposits within cds in several sub regions of europe were analysed and compared morphometric properties of cds from the west european and east european loess belt were investigated through a comparison of cds from two representative regions i e east poland and central belgium in both study areas cds under cropland are similar however a comparison of morphological features of cds under forest revealed clear differences suggesting a different origin of cds from both regions infilled sediments in cds show various litho genetical features in different regions of the european loess belt the morphometric features ages and stratigraphy of infillings clearly indicate that both anthropogenic and natural processes have shaped these landforms within the loess belt of europe cds observed in eastern europe may have a very different origin than those documented in western europe detailed analysis of cds in poland and in neighbouring regions of east europe suggest that cds are natural landforms thermokarst deflation and dissolution of loess are reported as probable genetic processes in contrast several studies in western europe indicate a dominant anthropogenic origin i e digging of calcareous loess or marls bomb and mining craters collapse of underground limestone quarries although cds formed by natural processes i e piping dissolution of limestone and salt lenses below the loess cover are reported as well cds act as important archives allowing one to reconstruct both natural and anthropogenic processes operating in the past as cds store most sediments eroded within their catchment they provide ideal sediment traps to assess long term erosion rates in these environments which have hitherto been under researched more research is needed to unravel the genesis and evolution of these depressions to better understand the importance of the late glacial and holocene stages for the morphogenesis of the loess belt in europe

spatial distribution of pipe collapses in goodwin creek watershed mississippi the internal erosion of soil pipes can induce pipe collapses that affect soil erosion processes and landform evolution the objective of this study was to determine the spatial distribution of pipe collapses in agricultural fields of goodwin creek watershed ground survey was carried out to detect pipe collapses and the location size and surface elevation was measured with differential gps a total of 143 of the 145 pipe collapses were found in cropland and the density was approximately 0 58 collapses per hectare the spatial distribution of pipe collapses was not uniform as pipe collapses were concentrated in the flat alluvial plains where the land use was dominated by cropland one of the four parcels had 90 of the pipe collapses with a density of 7 7 collapses per hectare the mean depth area and volume of these pipe collapses were 0 12 m 0 34 m2 and 0 02 m3 respectively and all these properties exhibited a skewed distribution the drainage area slope gradient equation which has been widely used for erosion phenomenon prediction did not represent pipe collapses in this study as the coefficient of determination was 0 01 this is clear evidence that subsurface flow is not represented by surface topographic characteristics the pipe collapses were found to intercept runoff thereby reducing the slope length factor by 6 and the drainage area by 7 both of these factors can reduce the sheet and rill erosion however the increased subsurface flow could enhance ephemeral gully erosion published 2012 this article is a u s government work and is in the public domain in the usa

evidence for holocene changes in australian indonesian monsoon rainfall from stalagmite trace element and stable isotope ratios abstract trace element and stable isotope ratios from an active stalagmite lr06 b1 recovered from liang luar cave on the island of flores eastern indonesia are used to reconstruct the position of the austral summer inter tropical convergence zone and australian indonesian summer monsoon variability during the holocene uranium series dating of the stalagmite shows that it commenced growth 12 640 years ago with hiatuses spanning 8 560 to 6 420 and 3 670 to 2 780 years ago stalagmite mg ca and sr ca ratios correlate significantly with one another and with 18 o and 13 c throughout the record this suggests that the mg ca and sr ca ratios are dominated by prior calcite precipitation a process whereby degassing in the vadose zone during periods of low recharge causes deposition of calcite and disproportionate loss of ca 2 ions relative to mg 2 and sr 2 upstream of the stalagmite the degree of initial 234 u 238 u disequilibrium also appears to have been controlled by recharge to the overlying aquifer together with the mg ca sr ca and 18 o values the initial uranium isotope activity ratios 234 u 238 u i imply a generally drier early holocene coincident with a lower sea level and lower southern hemisphere summer insolation comparison of speleothem 18 o time series from flores and borneo shows that they vary in unison for much of the holocene however there is a significant decrease in the borneo 18 o record 6 000 to 4 000 years ago that does not occur in the flores record this anomaly may be related to a change in the australian indonesian summer monsoon circulation in response to a protracted positive phase of the indian ocean dipole under this scenario stronger upwelling off of western indonesia would based on present day effects result in reduced summer convective activity over flores and a subsequent northward shift of the intertropical convergence zone

a speleothem record of younger dryas cooling klamath mountains oregon usa awell dated d 18 o record in a stalagmite from a cave in the klamath mountains oregon with a sampling interval of 50 yr indicates that the climate of this region cooled essentially synchronously with younger dryas climate change elsewhere in the northern hemisphere the d 18 o record also indicates significant century scale temperature variability during the early holocene the d 13 c record suggests increasing biomass over the cave through the last deglaciation with century scale variability but with little detectable response of vegetation to younger dryas cooling d 2005 university of washington all rights reserved

field testing of irrigation effects on the stability of a cliff edge in loess north west china as it is not uncommon that irrigation has triggered landslides in the chinese loess plateau a full scale field testing in a typical cracked plateau in heifangtai gansu province of china to simulate such phenomenon was conducted in the study piezometers were installed to measure the groundwater and crackmeters as well as inclinometers were used to measure the slope movement water was pumped from the nearby source daily to simulate the irrigation process there was a sharp increase of pore pressure in the undisturbed loess below the crack when the inclinometer registered considerable movement due to the inflow of water via the crack such increase in pore pressure also dissipated rapidly eventually the irrigation water daylighted at the major cracks from the face of the plateau leading to local failures the results show that cracks have significant effects on the flow of the irrigation water into the ground the rapid rise in the local pore water pressure had reduced the stability of the slope

lead and oxygen isotope evidence for the origin of the monte rosa gold lode deposits western alps italy a comparison with archean lode deposits in the monte rosa area of the northwestern italian alps swarms of epigenetic quartz sulfide gold bearing veins occur within a terrane affected by tertiary regional metamorphism of greenschist to amphibolite grade they are preferentially associated with the felsic rocks of the upper penninic nappes field evidence and available geochronologic data imply emplacement ages postdating the metamorphic peak 38 or 2 m y the spatial distribution of the veins is related to late metamorphic large scale tectonic disturbances which displace truncate or fold the isograds lead isotope analyses of galenas and other sulfides were compared with those of feldspars clinozoisites and whole rocks from various unaltered host rocks the data suggest derivation of the ore lead from caledonian metapelites with a possible contribution from hercynian granitoids but they rule out significant contributions from the neighboring ophiolitic greenstones and associated stratiform massive sulfide deposits the separation of the ore leads into two distinct data fields is probably the result of ore deposition from at least two hydrothermal systems which were separated in space and possibly also in time the hypothesis of two distinct mineralization ages is also supported by geochronologic data oxygen isotope data indicate that the ore fluids had isotopic compositions consistent with a metamorphic origin with the notable exception of the val toppa mine where lighter possibly surface derived water was involved oxygen isotope fractionations between mineral pairs in metasediments and granites indicate metamorphic peak temperatures of 530 degrees to 605 degrees c in agreement with those inferred from petrologic evidence these temperatures and preliminary fluid inclusion data were used to predict oxygen isotope compositions of gangue quartz the comparison of predicted with measured delta 18 o values shows consistency with the assumption that the fluids were generated by metamorphic devolatilization within the metapelites and granitoids in agreement with the lead isotope data the results suggest that the gold bearing fluids and the lead were supplied by rocks derived from the continental crust in opposition to the data from many greenstone hosted archean gold lode deposits which indicate a mantle source this implies that metamorphic hosted quartz gold lodes do not necessarily derive metals and fluids from source beds within a greenstone sequence therefore the assumption that the archean gold was derived from greenstones should be checked by isotope tracing studies the common lead method appears to be particularly promising in distinguishing greenstone metamorphic from granitic sources in precambrian terranes in view of the contrasting u pb ratios usually stated in these lithologies

experimental study on the effect of water gushing on loess metro tunnel in the construction of metro tunnels water gushing accidents caused by the rupture of underground pipeline often occur and in loess area the collapsibility of loess makes this problem more complex and difficult to investigate the damage of metro tunnel caused by collapsible loess under the action of local dynamic water gushing water a model experiment was conducted based on the pipeline water gushing accident happened in the construction of metro tunnel located in loess area through the study of similar materials of loess and tunnel lining the test materials and apparatus were prepared according to similarity criterion by simulating water gushing environment in the loess stratum this paper analyzed mechanical characteristics of tunnel water pressure of surrounding rock contact pressure and internal force of tunnel lining and deformation of surrounding rock and tunnel furthermore combining with the process of local collapse of loess in the model experiment it is concluded that the formation of water transport channel is the main reason for the difference of tunnel structural response when water gushing occurs at different locations finally a three dimensional spatial model of water transport channel in loess stratum under the environment of local water gushing was established to study the rule of water transport

palaeo climate reconstruction from stable isotope variations in speleothems a review abstract speleothems are now regarded as valuable archives of climatic conditions on the continents offering a number of advantages relative to other continental climate proxy recorders such as lake sediments and peat cores they are ideal materials for precise u series dating yielding ages in calendar years thereby circumventing the radiocarbon calibration problems associated with most other continental records stable isotope studies in speleothems have shifted away from attempting to provide palaeo temperature reconstructions to the attainable goal of providing precise estimates for the timing and duration of major o isotope defined climatic events characterised by high signal to noise ratios e g glacial interglacial transitions dansgaard oeschger oscillations the 8200 year event unlike the marine records speleothem data sets are not tuned and their independent chronology offers opportunities to critically assess leads and lags in the climate system that in turn can provide important insights into forcing and feedback mechanisms improved procedures for the extraction and measurement of stable isotope ratios in fluid inclusions trapped in speleothems are likely to provide in the near future a much enhanced basis for the quantitative interpretation of o isotope ratios in speleothem calcite the latter developments open up once again the tantalising prospect of palaeo temperature estimates but more importantly perhaps provide a direct test for a new generation of general circulation models whose hydrological cycles will incorporate the water isotopes the literature is reviewed briefly to provide for the reader a sense of the current state of the art and to provide some pointers for future research directions

characteristics controlling factors and importance of deep gullies under cropland on loess derived soils abstract several studies describe the formation and importance of shallow ephemeral gullies under cropland depth comparison of a dataset with 28 deep gullies formed in the period 1985 2003 and 123 shallow ephemeral gullies formed in the period 1994 1999 in central belgium indicates that the deep gullies have clearly different morphological characteristics compared to shallow ephemeral gullies several factors were analyzed to understand the formation of deep gullies plotting runoff contributing area versus slope of the soil surface at the gully head indicates that the topographical threshold for deep gully formation is significantly larger compared to ephemeral gully formation deep gullies form on short steep valley sides and their position is strongly affected by the presence of linear landscape elements all deep gullies incised on landscape positions with a very erodible soil horizon at shallow depth analysis of causative rainfall showed no significant differences in incision thresholds between rills and shallow ephemeral gullies on the one hand and deep gullies on the other hand the relation between area specific sediment yield in central belgium and drainage area indicates that the development of deep gullies contributes significantly to the sediment output of small rural catchments and causes peaks in the mean area specific sediment yield that are up to a factor of three higher compared with catchments where shallow ephemeral gullying occurs

carbon transfer dynamics from bomb 14c and δ13c time series of a laminated stalagmite from sw france modelling and comparison with other stalagmite records twenty two ams 14c measurements have been made on a modern stalagmite from sw france in order to reconstruct the 14c activity history of the calcite deposit annual growth laminae provides a chronology up to 1919 a d results show that the stalagmite 14c activity time series is sensitive to modern atmosphere 14c activity changes such as those produced by the nuclear weapon tests the comparison between the two 14c time series shows that the stalagmite time series is damped its amplitude variation between pre bomb and post bomb values is 75 less and the time delay between the two time series peaks is 16 years 3 a model is developed using atmosphere 14c and 13c data fractionation processes and three soil organic matter components whose mean turnover rates are different the linear correlation coefficient between modeled and measured activities is 0 99 these results combined with two other stalagmite 14c time series already published and compared with local vegetation and climate demonstrate that most of the carbon transfer dynamics are controlled in the soil by soil organic matter degradation rates where vegetation produces debris whose degradation is slow the fraction of old carbon injected in the system increases the observed 14c time series is much more damped and lag time longer than that observed under grassland sites the same mixing model applied on the 13c shows a good agreement r2 0 78 between modeled and measured stalagmite 13c and demonstrates that the suess effect due to fossil fuel combustion in the atmosphere is recorded in the stalagmite but with a damped effect due to som degradation rate the different sources of dead carbon in the seepage water are calculated and discussed

fluid inclusion geochemistry of high grade vein hosted gold ore at the pamour mine porcupine camp ontario this study was undertaken to characterize fluid inclusions associated with high grade vein hosted gold at the pamour mine in the porcupine camp of ontario and to compare them with fluid inclusions in quartz veins associated with wall rock hosted gold which is much more common the pamour mine contains two principal types of orebodies metasediment hosted fracture zones and larger metavolcanic or metasediment hosted quartz carbonate veins gold in the veins is distributed erratically attains very high grades locally and increases in grade at higher levels zoned alteration around the veins is dominated by addition of k 2 o co 2 as s and cao and depletion of na 2 o k 2 o co 2 and s are concentrated in the hanging wall and the intensity of co 2 and h super metasomatism increases upward in the mine roughly parallel to the trend seen in gold values gold was introduced along with sphalerite galena calcite chlorite and chalcopyrite late in the paragenetic history after brittle deformation of earlier vein hosted quartz tourmaline feldspar and pyrite sphalerite that is directly associated with high grade gold contains two types of primary inclusions a co 2 ch 4 fluid 20 45 mole ch 4 and an h 2 o rich liquid with a carbonaceous phase co 2 ch 4 as well as muscovite and graphite daughter minerals aqueous phase salinity estimates range from 2 to 9 equiv wt percent nacl and sem analyses of evaporitic residues of thermally decrepitated inclusions contain nacl and cacl 2 with lesser amounts of kcl mgcl 2 s zn and fe these two inclusion types appear to represent immiscible fluids trapped along the solvus in the h 2 o co 2 ch 4 salt system at temperatures of 325 degrees or 25 degrees c and pressures of 1 to 2 kbars these fluids are similar to those observed in vein quartz at the mcintyre and hollinger deposits where most gold is hosted by wall rocks except that co 2 immiscibility appears to have been more widespread at pamour the separation of immiscible fluids of the type identified in this study would increase the f sub o 2 and ph of the residual fluid owing to the partitioning of h 2 s ch 4 and co 2 into the carbonaceous phase the net effect of these changes would be to decrease the solubility of bisulfide complexed gold suggesting that co 2 immiscibility is an important contributor to gold deposition within veins where wall rock interaction is limited it is not clear whether all vein hosted gold formed from such unmixing or only the higher grade ore shoots

a coupled δ13c radiocarbon investigation of cave and soil processes recorded by three european speleothems during the late glacial and early holocene

the evolution of gully headcut morphology a case study using terrestrial laser scanning and hydrological monitoring we present observations and analysis of gully headcut erosion which differ from previous headcut studies in both spatial and temporal detail using ten terrestrial laser scanning tls surveys conducted over a period of 3 years we mapped headcut erosion with centimeter scale detail on a sub annual basis erosional change is observed through point cloud differencing which expands on previous studies of headcut retreat rate by revealing the evolution of the headcut morphology headcut retreat observations are combined with hydrological measurements to explore the controlling factors of erosional retreat we find that i mass failure due to wetting ii saturation weakening of shale bedrock in plunge pools and iii direct wash over the headcut face all appear to contribute to headcut retreat however mass failure via wetting appears to be the dominant process soil moisture was monitored near the study headcut at 0 4 m depth and time lapse photos show that soil wetting tends to be concentrated along the headcut apex after rainfall and snowmelt runoff events we find that moisture concentration at the headcut apex leads to more rapid erosion at that location than along the headcut sidewalls resulting in a semi ellipsoidal plan view morphology that is maintained as the headcut migrates up valley copyright 2015 john wiley sons ltd

use of lidar derived images for mapping old landslides under forest large deep seated landslides are common features in the flemish ardennes belgium as most of these old 100 years landslides are located under forest in this hilly region aerial photograph interpretation is not an appropriate landslide mapping method this study tested the potential of lidar light detection and ranging images for mapping old landslides under forest landslide inventory maps were created for a 125 km2 area by applying the expert knowledge of seven geomorphologists to lidar derived hillshade slope and contour line maps in a gis environment each of the seven lidar based landslide inventories was compared i with the other six ii with a detailed field survey based inventory and iii with a comparable study in which topographic data were extracted from a topographical map the combination of the percentage of field landslides indicated by an expert and the percentage of positional discrepancies expressed in terms of positional mismatch were used to evaluate the quality of the lidar based inventory maps high quality lidar derived landslide inventory maps contain more than 70 per cent of the landslides mapped during the field survey and have positional discrepancies smaller than 70 per cent when compared with the field survey based inventory map four experts and the combination map of all experts satisfied these criteria together the seven experts indicated all landslides mapped in the field importantly lidar enabled the experts to find ten new landslides and to correct the boundaries of eleven of the 77 landslides mapped during the field survey hence this study showed that large scale lidar derived maps analysed by experienced geomorphologists can significantly improve field survey based inventories of landslides with a subdued morphology in hilly regions copyright 2006 john wiley sons ltd

piping and pipeflow in a deep peat catchment abstract natural pipes are common in many upland blanket peats yet little is known about pipe network morphology or pipeflow processes most information on soil piping comes from the shallow peaty podzols of the welsh uplands where monitoring suggests that pipes may be important contributors to streamflow this paper presents information on piping and pipeflow from a deep upland blanket peat catchment in the pennine hills of northern england pipe outlets are found throughout the soil profile ranging from the underlying substrate at 3 m depth to pipes which are within a few centimetres of the surface mean pipe diameters range from 3 to 70 cm some pipes are over 150 m long slopes in the catchment are less steep than those usually associated with soil piping continuous flow records were obtained from 15 gauging sites on 8 separate pipes the pipeflow response from deep blanket peat was found to be different to that reported in the shallow peaty podzols of the welsh uplands the distinction between ephemeral and perennial pipe types does not appear to be useful within the deep pennine blanket peat response times from all of the pipes are short even from pipes deep within the peat at the same time pipes have a prolonged recession limb such that they maintain low flow for longer periods than most other runoff production processes within the catchment pipeflow contributes around 10 of the streamflow volume but can at times contribute up to 30 soil pipes may therefore be far more important in some upland peat catchments than previous work has hitherto suggested

wolframite deposition in a hydrothermal vein system the grey river tungsten prospect newfoundland canada mineralization in the grey river tungsten prospect newfoundland is contained within a sheared devonian k feldspar megacrystic granite and metamorphic rocks which are typical of the gneissic terrain of the gander zone the mineralization is genetically related to a suite of post tectonic highly differentiated alkali rich leucogranite dikes the tungsten bearing hydrothermal veins range from tensional veinlets to lodes containing several injections of quartz major composite lodes have greisen alteration envelopes which are characterized by enrichment in volatiles k 2 o al 2 o 3 rb li f heavy rare earth elements and w the heavy rare earth elements enrichment appears to be related to deposition of carbonate and fluorite in the greisen the mineralization is divided into four stages stage i characterized by quartz feldspar molybdenite veins stage ii composite lode formation consisting of five vein types in paragenetic order quartz bismuthinite iia quartz fe rich wolframite iib greisen iic quartz sulfide iid and quartz fe poor wolframite veins iie stage iii characterized by silver bearing quartz galena sphalerite veins and stage iv composed of fluorite calcite barite veins a spatial mineral zonation from south to north matches the temporal sequence outlined above with the exception of the stage iv veins which crosscut stage ii veins fluid inclusion data indicate a complex evolutionary history for the hydrothermal fluid the simultaneous trapping of co 2 rich and h 2 o rich fluid inclusions as well as solid inclusions of calcite in quartz of the quartz feldspar molybdenite and quartz bismuthinite vein types is evidence for the existence of a heterogeneous fluid during stage i and early stage ii mineralization fluid phase equilibria indicate that the inclusions were trapped at temperatures of 330 degrees to 360 degrees c and fluid pressures of less than 500 bars in composite lodes quartz sulfide and quartz fe poor wolframite veins were deposited in open spaces created by normal faulting these movements prompted rapid decrease in fluid pressure and temperature and caused retrograde boiling of the hydrothermal fluid at 200 bars and 300 degrees to 330 degrees c during deposition of quartz sulfide veins deposition of wolframite in quartz fe poor wolframite veins occurred at 270 degrees to 300 degrees c from an aqueous fluid of low salinity 0 5 wt nacl and low co 2 content 1 0 wt co 2 and after separation of a co 2 vapor phase by retrograde boiling isotopic and fluid inclusion data suggest that deposition of fe rich wolframite may have occurred at a slightly higher temperature 330 degrees c and from a fluid of higher co 2 content than the bulk of the wolframite which has an fe poor composition progressive co 2 loss from the hydrothermal fluid by immiscibility and retrograde boiling had a marked effect on the solution ph which shifted from 5 weakly acid to 6 weakly alkaline at 300 degrees to 350 degrees c during tungsten deposition thermodynamic data on the solubility of wolframite suggest that a ph increase would provide an effective mechanism for tungsten deposition and explain the variation in wolframite composition from fe rich to fe poor with time the association of hematite fe rich wolframite and muscovite in the greisen suggests high f sub o 2 10 super 20 10 super 30 conditions and is supported by eu behavior during alteration sulfides formed after tungsten deposition at temperatures less than 300 degrees c and under f sub s 2 conditions of less than 10 super 11 co 2 rich fluids are commonly associated with tungsten deposits from a variety of environments and the evidence from the grey river tungsten prospect shows that co 2 plays an important role in the transport and deposition of tungsten in the hydrothermal environment

impact of soil characteristics on piping activity in a mountainous area under a temperate climate bieszczady mts eastern carpathians abstract this paper aims at a better understanding of the role of soil characteristics in piping activity in a mountainous area under a temperate climate the recognition of favourable soil properties is widely described in badlands with dispersive materials and in loess covered hilly regions in other regions without dispersive materials or without extensive loess deposits piping conditions draw hardly any attention the survey was carried out in the tyskowa catchment in the bieszczady mts eastern carpathians we focused on soil characteristics that can impact erodibility including texture structure consistence porosity and bulk density these characteristics as well as selected chemical properties ph exchangeable cations and sodium absorption ratio sar were studied in detail for 4 soil profiles with a different position in relation to collapsed pipes cps on a slope with abundant cps and on one lacking cps we tested a hypothesis that soil properties control the occurrence of pipes and we checked if there is any difference in soil properties on slopes with and without cps moreover we compared soil profiles within the slope with cps additionally detailed geomorphological mapping of piping forms was carried out in the selected catchment in order to determine the depth of the pipe formation no clear difference in soil characteristics was observed between the slope with high piping activity and the one without it with cambisols occupying both sites the soils exhibit a large content of silt which potentially enhances piping the chemical properties do not differ among the analysed soils however the profiles at the site above cps with potential piping and in the sinkhole are characterized by intense biological activity the development of soil structure in deeper horizons angular and subangular blocky structure down to 90 105 cm high porosity and low bulk density to summarize it is the combination of biological activity and soil properties silty texture well developed soil structure low bulk density and high porosity that determines the formation of pipes in the study area combining all the results from the soil profiles and the depth of pipes indicates that pipes develop on the boundary of b and c soil horizons and the mean depth of pipe formation is almost 0 80 m with the maximum of 1 55 m

identification of sinkhole origin using surface geophysical methods dead sea israel abstract the western and eastern dead sea ds shores are hit by intensive sinkhole collapse during the last 30 years the first researchers have considered a piping model of sinkhole formation based on washing out fines by underground flows then it was proved by numerous boreholes and seismic refraction surveys that sinkholes along western shore are caused by dissolution of buried salt layers and collapse of the surface into dissolution caverns however signs of piping and subsurface flows were observed in some sinkhole sites in this paper we show that robust identification of sinkhole origin can be achieved when proper geophysical methodologies and their application are used we consider newe zohar site located in the southern part of the dead sea in order to analyse different signs of sinkhole formation models using various geophysical methods the seismic refraction method srfr enables us to discover the salt layer based on longitudinal wave velocity vp the multichannel analysis of surface waves masw method allows to determine the salt layer properties rigidity based on shear wave velocity vs finally the time electromagnetic tem method allows us to evaluate the degree of aggressiveness of groundwater with respect to salt based on bulk resistivity values here we analyse competitive models of sinkhole formation and suggest geophysical methods to determine the subsurface geomorphology we show that various geophysical methods should be applied in concert to explore the subsurface for the occurrence of salt as well as understanding sinkhole formation processes the underlying voids along the dead sea are shown to form primarily by salt dissolution with some cases of additional piping applying the right geophysical parameters for groundwater and salt sediments classification proves to be crucial for understanding the subsurface geomorphology

the gold carbonate association source of co2 and co2 fixation reactions in archaean lode deposits abstract abundant carbonate is a ubiquitous feature of archaean lode gold deposits both in domains of alteration enveloping veins and in rocks enclosing auriferous sediments detailed studies of chemical mass balance in metabasalts progressively altered towards gold bearing quartz carbonate veins disposed within shear zones at yellowknife reveal massive additions of co2 k si and fe accompanying mineralisation with concomitant depletions of na coherent behaviour of al sc zr also v and nb provides a reference for constraining the volume relations during hydrothermal alteration in the peripheral regions of alteration depletions of ca and mg result in overall volume reduction but these elements are added to veins and their immediate alteration envelopes where there is a large positive volume change precious metals together with cr ni cu zn pb rb cd and ba have been added to the veins and altered wall rocks whereas quartz noble metals and other trace elements have been precipitated from hydrothermal fluids solution of ca mg and some fe indigenous to peripheral alteration regions combining with co2 from the mineralising reservoir appears to be the process for forming the abundant ferri dolomite gangue observations of many archaean au deposits reveals that carbonate chemistry reflects the nature of wall rocks with wall rocks donating the bivalent metal cations and hydrothermal fluids the co2 alteration reactions at yellowknife involved hydrolysis of albite accompanied by fixation of kaqueous to produce muscovite with na loss and hydrolysis of chlorite epidote with co2 fixation to form ferri dolomite studies of oxygen isotopes fe 2 fe 2 fe 3 and structure reveal that au quartz and carbonate were precipitated in the presence of fluids of probable metamorphic origin 18 o 8 9 at low redox potential and at ambient temperatures of 400 450 c during episodes of hydrofracturing the abundant co2 and k required for extensive carbonate muscovite replacement alteration could be supplied by fluids released during prograde metamorphism under greenschist or greenschist amphibolite facies conditions where the relative proportion of co 2 h 2 o is in the order of 0 2 to 0 5 and k na 1 given high co2 co in the hydrothermal reservoir these molecules may act as complexing agents for transport of au and other rare elements e g w pd ni cr