comparing physiographic maps with different categorisations abstract this paper addresses the need for a robust map comparison method suitable for finding similarities between thematic maps with different forms of categorisations in our case the requirement was to establish the information content of newly derived physiographic maps with regards to set of reference maps for a study area in england and wales physiographic maps were derived from the 90 m resolution srtm dem using a suite of existing and new digital landform mapping methods with the overarching purpose of enhancing the physiographic unit component of the soil and terrain database soter reference maps were seven soil and landscape datasets mapped at scales ranging from 1 200 000 to 1 5 000 000 a review of commonly used statistical methods for categorical comparisons was performed and of these the cramer s v statistic was identified as the most appropriate for comparison of maps with different legends interpretation of multiple cramer s v values resulting from one by one comparisons of the physiographic and baseline maps was facilitated by multi dimensional scaling and calculation of average distances between the maps the method allowed for finding similarities and dissimilarities amongst physiographic maps and baseline maps and informed the recommendation of the most suitable methodology for terrain analysis in the context of soil mapping

a steady state analytical slope stability model for complex hillslopes this paper presents a steady state analytical hillslope stability model to study the role of topography on rain induced shallow landslides we combine a bivariate continuous function of the topographic surface a steady state hydrological model of hillslope saturated storage and the infinite slope stability assumption to investigate the interplay between terrain characteristics saturated storage within hillslopes and soil mechanics we demonstrate the model by examining the stability of nine characteristic hillslope types landform elements with three different profile curvatures concave straight and convex and three different plan shapes convergent parallel and divergent for each hillslope type the steady state saturated storage corresponding to given recharge rates is computed for three different average bedrock slope angles on the basis of the infinite slope stability method the factor of safety fs along the hillslopes is determined our results demonstrate that in the steep slopes the least stable situation occurs in hillslopes with convergent plan shapes and concave length profiles while the convex ones are more stable in addition to testing our method for nine characteristic hillslope types a general relationship between plan shape and profile curvature of landform elements and the factor of safety is derived for a pre defined hillslope length scale our results show that slope stability increases when profile curvature changes from concave to convex in terms of plan shapes changing from convergent to divergent slope stability increases for all length profiles however we find that the effect of plan shape is more pronounced for convex length profiles overall we demonstrate that in addition to bedrock slope hillslope shape as represented by plan shape and profile curvature is an important control on hillslope stability

quantification of spatial gradation of slope positions transition between slope positions e g ridge shoulder slope back slope foot slope and valley is often gradual quantification of spatial transitions or spatial gradations between slope positions can increase the accuracy of terrain parameterization for geographical or ecological modeling especially for digital soil mapping at a fine scale current models for characterizing the spatial gradation of slope positions based on a gridded dem either focus solely on the parameter space or depend on too many rules defined by topographic attributes which makes such approaches impractical the typical locations of a slope position contain the characteristics of the slope position in both parameter space and spatial context thus the spatial gradation of slope positions can be quantified by comparing terrain characteristics spatial and parametrical of given locations to those at typical locations based on this idea this paper proposes an approach to quantifying the spatial gradation of slope positions by using typical locations as prototypes this approach includes two parts the first is to extract the typical locations of each slope position and treat them as the prototypes of this position and the second is to compute the similarity between a given location and the prototypes based on both local topographic attributes and spatial context the new approach characterizes slope position gradation in both the attribute domain i e parameter space and the spatial domain i e geographic space in an easy and practicable way applications show that the new approach can quantitatively describe spatial gradations among a set of slope positions comparison of spatial gradation of a horizon sand percentages with the quantified spatial gradation of slope positions indicates that the latter reflects slope processes confirming the effectiveness of the approach the comparison of a soil subgroup map of the study area with the maximum similarity map derived from the approach also suggests that the quantified spatial gradation of slope position can be used to aid geographical modeling such as digital soil mapping c 2009 elsevier b v all rights reserved

landform classification and soil distribution in hummocky terrain saskatchewan canada this study presents a classification of distinct three dimensional landform elements and examines the relationship between these landform elements and selected soil morphological properties of udic boroll soils in southern saskatchewan canada the classification is based on defined ranges of three criteria derived from topographic data gradient profile downslope curvature and plan across slope curvature seven landform elements are recognized convergent shoulders divergent shoulders convergent backslopes divergent backslopes convergent footslopes divergent footslopes and level elements all of the elements are easily identified in the field the thicknesses of a horizons and depths to calcium carbonate of the soils were consistently greater in convergent versus divergent elements in the same profile group e g shoulders and showed an overall increase in the sequence shoulders backslopes level footslope elements distinct groups of elements emerge from a statistical analysis of the differences between individual and bivariate means of soil morphological properties associated with each landform element the differences in soil properties among the elements can be largely explained by differences in water movement and distribution in hillslope systems the results of the study highlight the need to consider land surface morphology during the development of research designs for soil related studies

geomorphic mapping and taxonomy of fluvial landforms abstract fluvial geomorphologists use close to a 100 different terms to describe the landforms that make up riverscapes we identified 68 of these existing terms that describe truly distinctive landforms in which form is maintained under characteristic conditions and fluvial processes clear topographic definitions for these landforms to consistently identify and map them are lacking with the explosion of continuous high resolution topography and digital elevation models we have plenty of new basemaps in which these landforms are clearly visible but very few examples of manual or automated classification of fluvial landforms fluvial landforms are the building blocks of a river and are variously referred to as geomorphic units morphological units habitat units and channel units we present a tiered framework for describing geomorphic units with tier 1 differentiating units on the basis of their stage tier 2 separating shape e g concave convex or planar tier 3 using particular key attributes to narrow in on the likely specific geomorphic unit type and tier 4 differentiating those types on the basis of vegetative or roughness modifiers information on the assemblage and configuration of geomorphic units can be used to inform process based interpretations of the range of river behavior the accuracy and transferability of such analyses is fundamentally tied to the taxonomy we assign to these discrete building blocks in this paper we clarify the terminology and definitions relating to the identification and delineation of geomorphic units margins and structural elements we establish a set of procedures that can be used to manually map and identify these features the proposed framework provides a rigorous and repeatable approach to identification of topographically defined features of riverscapes we demonstrate the application of these systematic yet flexible procedures with a series of maps from rivers in differing valley settings

delineating the major landforms of catchments using an objective hydrological terrain analysis method 1 the location and distribution of landform shape and size describe and categorize many features of a catchment landforms indicate soil types arability of land geological features hydrological influences and even shallow groundwater systems this paper describes an objective method for delineating major landforms of a catchment on the basis of hydrological terrain analysis it allows comparisons to be made within and between catchments the method uses the upness index from the fuzzy landscape analysis geographic information system flag model roberts et al 1997 that is derived from digital elevation data upness was developed as an index of surface and shallow subsurface water accumulation in the method presented in this paper we fit a five parameter sigmoidal function to the cumulative distribution function cdf of the natural log ln of upness the point of inflection of the cdf of the upness index is defined from the first derivative of the five parameter sigmoidal function as the point of maximum concavity the second and third points are defined by determining the maximum upward concavity and minimum downward concavity from the second derivative of a five parameter sigmoidal function referred to as break points the inflection and break points from the upness index are used to segment the cdf into three regions that represent four different landform elements landform categories based on these points represent ridge tops and upper slopes midslopes lower slope and in filled valley alluvial deposits the shape of the cdf curve indicates the dominance of major landforms within a catchment providing an objective means for classifying this catchment characteristic examples are given showing how landform discrimination compares to geological maps the landforms index presented in this study offers a useful technique for differentiating complex landforms from a landscape using terrain analysis that attempts to represent dominant hydrological soil formation processes

hydrothermal alteration and ree th mineralization at the rodeo de los molles deposit las chacras batholith central argentina ree rare earth element and th mineralization at the rodeo de los molles deposit occurs within an elliptical body of hydrothermally altered rocks fenite located in a biotite monzogranite of the las chacras batholith ore assemblages are found as isolated patches of intergrown britholite allanite apatite bastnaesite fluorite sphene quartz and aegirine augite as well as nodules of uranothorite and late stage veins of calcite fluorite and bastnaesite composition volume computations suggest that the fenite was produced by alteration of the biotite monzogranite by addition of k and na and loss of ca and sr petrographic evaluations indicate that microcline and plagioclase have been replaced by perthite and biotite was converted to aggregates of clinochlore anatase kaolinite and hematite relict biotite is characterized by lower fe fe mg and ti values with progressive alteration fluorine rich phlogopite is present in mineralized areas but textural evidence suggests that it was not produced via biotite alteration mass balance constraints also show that ca and mg in ore zones may result from redistribution rather than their being a result of external derivation the 18o values of quartz 8 6 11 1 and feldspar 7 8 10 6 suggest that feldspar continued to exchange oxygen isotopes with a fluid to lower temperatures than did quartz feldspars equilibrated with a fluid of 18o 8 at a fluid rock ratio less than 1 the 18o values of quartz and aegirine augite that crystallized during ree mineralization also suggest equilibration with a fluid of 18o 8 the d values of biotite 83 to 120 are relatively low for igneous rocks and are thought to have resulted from exsolution of a d enriched magmatic vapor the d values of both mineralized and barren fenites are consistent with equilibration with fluid of magmatic origin meteoric water was involved in the production of calcite and clinochlore alteration and late stage calcite fluorite bastnaesite veins the 13c values of calcite and bastnaesite 7 8 to 13 5 suggest that carbon was derived by leaching of carbon from igneous and or enclosing metamorphic rock types and that a majority of carbon ultimately was derived from sedimentary organic meterial

soil variations on hillslopes in humid temperate climates abstract considerable insight into the nature and causes of soil variations on hillslopes has been provided by studies which have incorporated both pedological and geomorphological concepts into their methodology even so there is still a great deal of uncertainty concerning the relationships between soils and landforms this paper attempts to outline the conceptual and methodological issues involved in such a synthesis by examining the nature of soil variation on specific examples of landscapes in humid temperate climates it has not been possible to examine soils across the whole of this region but soil landform relationships on the chalk of southeast england the granite uplands of dartmoor and in the wyre forest of england have been used to examine a number of well established principles one of these principles is that many landscapes possess slopes with easily identifiable toposequences the hillslopes analysed have shown that relationships do exist between soils and landforms but the idea that many slopes are integrated along their entire length is not necessarily true individual components of slopes possess soil characteristics that appear to be related to the morphological nature of those components but the slopes as a whole do not possess integrated soil systems different parts of the slope appear to act independently this questions the validity of employing traditional concepts such as that of the catena in soil landform relationships

relationship between the flank sliding of the south east crater mt etna italy and the paroxysmal event of november 16 2006 over the last 2 years the south east crater sec at mt etna italy has been characterised by the intermittent emission of lava flows often accompanied by paroxysmal episodes with violent strombolian activity and or lava fountains one of the most intense and intriguing episodes occurred on november 16 2006 during strombolian and effusive activity from the very top of the sec at the eastern base of the crater a violent and short lasting outburst generated a 300 m high eruptive curtain of finely fragmented magma and steam which collapsed in a few seconds giving rise to a small but significant pyroclastic flow the paroxysm was preceded by progressive sliding of the eastern flank of the sec edifice which led to the formation of a large niche previously published models explain the outburst as due to rapid vaporisation of water contained in sediments on contact with hot lava flowing along the flank of the sec or alternatively to gravitational collapse of a destabilised portion of the eastern flank of the crater however several lines of evidence suggest that these models do not adequately explain the paroxysm which we propose was associated with the explosive emission of magma during the rapid opening of an ese wnw oriented fracture at the eastern base of the sec moreover geochemical data of the products associated with this episode show that they are the most primitive and gas rich among those erupted during the entire 2006 period we suggest that the paroxysm of november 16 2006 which occurred at base of the sec was a magma outburst due to rapid ground fracturing related to a drop in confining pressure upon the underlying dyke consequent to the sliding of the eastern flank of the sec cone specifically the unloaded shallow portion of the feeding dyke did not restrain the arrival of a new batch of gas rich magma which worked its way out by fracturing the base of the niche at its weakest point this paroxysm appears significant because it reveals the potential development of syn eruptive dynamics acting directly on the uppermost portion of the plumbing system which is able to generate pyroclastic flows even on basaltic volcanoes such as mount etna

responses to and the short and long term impacts of the 1957 1958 capelinhos volcanic eruption and associated earthquake activity on faial azores the 1957 58 capelinhos eruption on faial island in the azores is well known for being an excellent example of surtseyan hydromagmatic volcanic activity less well known are the responses of the portuguese authorities to the eruption and subsequent earthquake in may 1958 and the ways in which well thought out and generally effective recovery programmes were put in place at the time portugal was ruled by a dictatorship the estado novo new state only superficially similar to other fascist governments in southern europe the estado novo collected huge amounts of data on the responses of the authorities to the disaster and their programmes of recovery but never encouraged academic evaluation of policy although it ensured that the scientific aspects of the eruption and earthquake were meticulously recorded and published in this paper we remedy this situation by discussing the details of the immediate response to the emergency and the ways in which the island recovered in its aftermath the study is based not only on archival sources and demographic and economic data but also on detailed interviews with survivors some of whom were also decision makers we argue that response recovery and rehabilitation were generally highly successful and assess the lessons of the 1957 58 emergency which are relevant to future geophysical disasters in faial and the wider azores since the 1974 revolution portugal has been a democratic state we conclude that both the legislation and the civil defence infrastructure necessary to achieve a similarly strong and successful response are in place today

a multi methodological re evaluation of the volcanic events during the 1580 ce and 1808 eruptions at sao jorge island azores archipelago portugal abstract among all eruptions that took place on the azores archipelago since the portuguese settlement in the xvi century those of 1580 and 1808 in the island of sao jorge were unusual the magma erupted in 1580 ascended from at least 23 km and ponded at a minimum depth of 16 km here residual magma fractionated mafic phases and plagioclase during 228 years before erupted again in 1808 magma emission occurred from numerous fissures active at the same time and opening for several kilometres following a local tectonic trend hydro volcanic outbursts and hot rock fall over steep slopes caused casualties and injuries and lava flows and heavy tephra fallout affected the local economy despite of all these dramatic consequences the memory of these eruptions is almost vanished representative geosites and morphological landforms if not hindered by lush vegetation have been reshaped by diffuse quarries and reworked to recover croplands and pastures aiming at a better comprehension of the multiple hazards associated with volcanic eruptions at sao jorge island we retraced the volcanic events of these two eruptions by matching our re interpretation of historic reports with field data and photogrammetry and with fluid inclusions petrography and geochemical data of erupted products

predicting soil classes with parameters derived from relief and geologic materials in a sandstone region of the vosges mountains northeastern france abstract the present study involves the possibility of using geology and relief to map soil classes we initially focused on two small catchments considered as representative of a 6000 ha forested area overlying a sandstone bed the catchments differed in the stratigraphic sequence of sandstones i e rich or poor in weatherable minerals in one the depleted bedrock was downstream and the rich was upstream and the converse obtained for the second relationships between soil classes and environmental factors were modeled using two discriminant functions corresponding to the two types of stratigraphic sequences found in the catchments more than 70 of the soil class distribution in small catchments can be explained by the nature of the substratum and attributes derived from a digital elevation model dem these relationships were then applied to a larger region an automatic catchment delineation was first carried out with the dem and was then combined with geologic maps the choice between the two discriminant functions was based on the stratigraphic sequences in each catchment predicted soil classes were compared to soil classes conventionally mapped in 1978 at the scale of 1 100 000 the results show that the model reproduced the soil map over 55 of the area studied disagreements were due primarily to the existence of superficial deposits not mentioned on the geologic maps and to an altitude effect that is not sufficiently considered in the study of small catchments

modelling the spatial variation of processes in the redistribution of soil digital terrain models and 137cs in southwest niger abstract an interpolated grid based digital elevation model dem was created from survey data to derive two compound topographic indices a stream power index to provide a surrogate measure of water erosion and an index of susceptibility to aeolian processes maps of both indices were compared with a map of interpolated percentage 137 cs residuals used as a surrogate for net soil redistribution over the last ca 30 years results suggest that wind erosion is pervasive throughout the study area whereas water erosion is concentrated on the steeper slopes areas of potential aeolian deposition were identified on the lee side of obstacles but were validated in only a few cases by the map of 137 cs residuals this anomaly probably results from considerable reworking of aeolian material deposited in the lee of obstacles on slopes highly susceptible to water erosion although the digital terrain models dtms could not explain the pattern of 137 cs residuals in some locations the inclusion of the percentage of vegetation cover further elucidated the patterns of soil redistribution vegetation cover was found to explain a considerable amount of variation in the patterns of soil redistribution over the medium time scale further research into the modelling of these processes is necessary to elucidate the pattern of vegetation cover removal and its link with soil redistribution

pyroclastic density currents resulting from the interaction of basaltic magma with hydrothermally altered rock an example from the 2006 summit eruptions of mount etna italy after 16 months of quiescence mount etna began to erupt again in mid july 2006 the activity was concentrated at and around the southeast crater sec one of the four craters on the summit of etna and eruptive activity continued intermittently for 5 months during this period numerous vents displayed a wide range of eruptive styles at different times virtually all explosive activities took place at vents at the summit of the sec and on its flanks eruptive episodes which lasted from 1 day to 2 weeks became shorter and more violent with time volcanic activity at these vents was often accompanied by dramatic mass wasting processes such as collapse of parts of the cone highly unusual flowage processes involving both old rocks and fresh magmatic material and magma water interaction the most dramatic events took place on 16 november when numerous rockfalls and pyroclastic density currents pdcs were generated during the opening of a large fracture on the se flank of the sec cone the largest pdcs were clearly triggered explosively and there is evidence that much of the energy was generated during the interaction of intruding magma with wet rocks on the cone s flanks the most mobile pdcs traveled up to 1 km from their source this previously unknown process on etna may not be unique on this volcano and is likely to have taken place on other volcanoes it represents a newly recognized hazard to those who visit and work in the vicinity of the summit of etna

a new procedure for gridding elevation and stream line data with automatic removal of spurious pits abstract a morphological approach to the interpolation of regular grid digital elevation models dems from surface specific elevation data points and selected stream lines is described the approach has given rise to a computationally efficient interpolation procedure which couples the minimization of a terrain specific roughness penalty with an automatic drainage enforcement algorithm the drainage enforcement algorithm removes spurious sinks or pits yielding dems which may be used to advantage in hydrological process studies the drainage enforcement algorithm has also been found to significantly increase the accuracy of dems interpolated from sparse but well chosen surface specific elevation data moreover it facilitates the detection of errors in elevation data that would not be detected by more conventional statistical means and forms a sound physical basis for cartographic generalization

a semi automated method for mapping glacial geomorphology tested at breiðamerkurjokull iceland abstract despite advances in data collection and analytical software mapping of glacial geomorphology is still largely achieved through manual techniques manual mapping is a relatively slow inefficient and potentially subjective process particularly given the extensive spatial coverage of remotely sensed datasets thus glacial geomorphic mapping would benefit from semi automated techniques able to map large areas quickly and efficiently here we develop novel semi automated techniques for mapping glacial geomorphology based on lidar derived data collected from brei amerkurjokull iceland using object based image analysis obia the landforms classified were moraines eskers flutes drumlins and glacio fluvial outwash several land surface parameters lsps were calculated during image segmentation and analysis representing the characteristics of the landforms of interest the segmentation and classification routines were developed in matlab whereas most attempts so far have used specialised obia software our techniques utilised exploratory data analysis where statistical groupings within the data define different landform types accuracy was assessed against a reference map derived using traditional manual mapping techniques landforms were classified to an overall accuracy of 77 our semi automated mapping techniques should with further algorithm development be applicable using other datasets commonly used in palaeo glaciology such as radar derived elevation data and swath bathymetry

origin of the term nuees ardentes and the 1580 and 1808 eruptions on sao jorge island azores abstract in this paper we provide a brief account of the 1580 and 1808 eruptions on sao jorge in the azores which produced pyroclastic density currents pdcs discuss the first recorded use of the term nuees ardentes to describe these pdcs trace how this term was introduced into the scientific literature and discuss its adoption by alfred lacroix 1863 1948 to describe the glowing clouds produced by mt pelee martinique in 1902 the 1580 and 1808 eruptions on sao jorge are important because they provide early descriptions of pdcs documentary evidence of the eruptions and their impacts suggest that the 1580 pdc was a hotter flow whereas the 1808 pdcs were cooler and more moist contemporary accounts describe the 1580 pdc as a globe of fire mixed with caustic smoke and moving at speed towards the bottom of the slope in contrast the 1808 pdcs comprised humid ash were not incandescent and it is likely that the flows were cooler than that produced in 1580 since the eruption of mt pelee in 1902 it has been widely accepted that the term nuees ardentes was introduced by lacroix 1904 being based on his description of the pyroclastic flows that he witnessed lacroix acknowledges that the portuguese expression nuvem ardente was first used in contemporary accounts of the sao jorge pdcs this was first translated as nuee ardente and introduced into the scientific by the french geologist ferdinand fouque 1828 1904 who was also lacroix s father in law indeed lacroix provides an account of the 1580 and 1808 eruptions of sao jorge in his 1904 work la montagne pelee et ses eruptions the seminal work of frank alvord perret 1867 1943 on the 1929 32 eruptions of mt pelee and his description of nuees ardentes probably helped reinforce the association between the term and mt pelee

soil properties and their variations on two contiguous hillslopes in northeast brazil abstract information on spatial distribution of soil properties in a landscape is not only required for soil mapping and classification but also for soil management spatial patterns of soil properties in a landscape are the results of systematic variations in pedogenic processes controlled by environmental factors of which landscape position is important in northeast brazil lithosols ustorthents whose surface horizons are directly underlain by lithic or paralithic contacts occupy upper slope positions with steep gradient the cambisols ustropepts occupy the mid and lower slope positions in some cases non calcic brown soils planosol haplustalfs occupy lower slopes we examined the properties of two contiguous hillslopes in granitic and gneissic saprolite to determine whether there were any systematic variations among landscape positions and to interpret pedogenesis in the hillslopes particle size distribution and the ti content of sand plus silt and saprolite showed that the two hillslopes were formed on different parent materials at site 1 soil property variations along the slope measured by standard deviation from the means were attributed to variability in parent material rather than to landscape position except for solum thickness which increased systematically downslope variations in sand clay ecec and ph were not related to landscape position increasing solum thickness downslope was explained by the effect of erosion on the upper and deposition at the lower slopes silt and organic carbon contents at site 1 and feo and fed contents at site 2 significantly decreased downslope one possible explanation for this trend in addition to erosion and deposition is the effect of slash and burn agriculture on the lower slopes and the changes in redox conditions caused by periodic waterlogging

saturation regions in catchments and their relations to soil and topographic properties abstract criteria are derived for the existence of saturated areas on draining hillslopes in natural catchments these are given in terms of soil transmissivity the hillslope gradient and its wetness state characterised by the baseflow discharge from the catchment analyses are made for idealised hillslopes with uniform soils to obtain expression for the width of the saturated zone the size of saturated zones on undulating hillslopes with gradiational soils is shown to depend strongly on topographic convergence or divergence the effects of soil transmissivity hillslope geometry and drainage flux density are lumped into a dimensionless parameter whose value determines the location of seepage boundaries on slopes of specified geometry scaling relations for seepage area in catchments of different size are shown to be generally nonlinear and depend primarily on local hillslope gradients relative predictions of seepage zone size are confirmed by observed hydrographs from three catchments with different physical characteristics

soil landscape modeling across a physiographic region topographic patterns and model transportability abstract soil landscape modeling techniques have been developed as a quantitative method to predict patterns of soil properties from observed patterns in soil forming factors however transportability of these models to unsampled landscapes is unknown our objective was to develop quantitative soil landscape models for multiple study sites and examine the similarity of these quantitative models and therefore the similarity of soil landscape relationships among areas with similar soils we collected high resolution digital elevation models dem for six study sites across the pennyroyal physiographic region of kentucky and for each study site used terrain attributes derived from the dem to collect discrete soil samples using a stratified random sampling design for morphological physical and chemical characterization for three of these sites we examined the inherent differences in terrain attributes among sites and developed quantitative soil landscape models that predict the spatial patterns in a horizon depth surface soil organic carbon content and surface sand and silt content the other three sites were used to test the transportability of these models terrain attribute distributions differ significantly among study sites with regional terrain attributes upslope contributing area topographic wetness index being more similar among fields than local terrain attributes slope gradient slope curvature predictive models explained from 28 to 67 of the variation in soil properties the terrain attributes that best predicted soil variability were similar across all three fields used for model development with slope gradient elevation slope curvature and upslope contributing area appearing in most of the models however applying models from one field to other fields within the same physiographic region produced inconsistent results in general prediction quality decreased with distance from the site of model development further sampling modeling and validation at additional field sites are required to properly establish model transportability

sodium calcium metasomatism chemical temporal and spatial relationships at the yerington nevada porphyry copper deposit tilting associated with extensional tectonics has exposed 1 800 m of continuous palcovertical relief through the jurassic age yerington porphyry copper deposit the rarely observed root zones of a porphyry system are characterized at yerington by sodium calcium metasomatism the principal hydrothermal reactions involve the replacement of primary k feldspar by oligoclase and of primary biotite by actinolite copper has been removed sodic calcic alteration developed at deep intrusive contacts nearly simultaneously with potassic alteration and copper mineralization at shallow intrusive contacts the reactions accompanying potassic alteration are the reverse of those accompanying sodic calcic alteration plagioclase reacted to form k feldspar hornblende reacted to form biotite the potassic and sodic calcic alteration couplet principally accompanied each of two separate intrusive events 1 luhr hill granite stock and associated porphyry dikes and 2 walker river granite porphyry dikes the younger walker river intrusion was emplaced at slightly deeper levels than the older luhr hill complex vertically stacked and partially superimposed alteration and mineralization patterns resulted from differences in depth and in timing of emplacement at lower temperatures late sodic alteration was superimposed on early sodic calcic alteration at deeper levels in the system whereas late quartz sericite pyrite alteration was superimposed on potassic alteration at higher levels sodic alteration is characterized by the replacement of k feldspar by albite and of biotite by chlorite copper deposited during potassic alteration was remobilized the transition to lower temperature alteration is associated only with the walker river intrusion the hydrothermal system associated with the emplacement of the luhr hill complex had not evolved to lower temperature assemblages prior to emplacement of the walker river dikes phase equilibria and geologic reconstruction of depth of emplacement suggest that temperatures during early sodic calcic alteration were limited to the range of 360 degrees to 480 degrees c at pressures between 300 and 800 bars late sodic alteration took place at similar pressures but at temperatures less than 360 degrees c nearly simultaneous development of potassic and sodic calcic alteration resulted from the flow of fluids away from intrusions at shallow levels potassic alteration and from the flow of fluids toward intrusions at deeper levels sodic calcic alteration because k na and na ca activity ratios of a fluid in equilibrium with granitic rocks decrease with decreasing temperature cooling of high temperature fluids can generate potassic alteration and heating of fluids to high temperatures can generate sodic or sodic calcic alteration

optimisation of relief classification for different levels of generalisation abstract relief plays an important role in the spatial and temporal distribution of soil water and matter transport processes each landscape can be segmented into different landform elements based on a digital elevation model these landforms contain characteristic properties in terms of energy and material balance several algorithms are available to classify landscapes at different scales however lack of knowledge exists concerning the applicability of relief parameters for landscape stratification for different generalisation levels of underlying data the objective of this study was to develop a method for agricultural landscapes to classify landform elements across a series of elevation datasets with different spatial resolutions a non linear parameter optimisation algorithm was coupled with a relief classification scheme to optimize four classification parameters with regard to environmentally sensitive landforms shoulder and footslope input datasets were based on a lidar scan and topographic maps the magnitude of the optimized relief parameters decreased with decreasing map scale from 1 10 000 to 1 100 000 or increasing contour line interval the main conclusion is that if one set of classification rules for a specific landscape was determined for a high resolution dataset at a small subset it could be applied for larger areas even if only coarser digital elevation model information were available

spatial delineation of organic carbon rich colluvial soils in chernozem regions by terrain analysis and fuzzy classification abstract colluvial soils are considered to be the direct result of accelerated soil erosion resulting in accumulation of humus rich soil material in terrain depressions and base parts of slopes the organic carbon concentration in these soils and their depth make them an important organic carbon storage mapping the colluvial soils therefore represents an important contribution in total carbon stock estimation a method of delineating colluvial soils is proposed by applying a combination of high resolution digital elevation model analysis and detailed field survey two models based on fuzzy classification of soil units were created using different topographic derivatives as the only input parameters to predict the colluvial soil area on a morphologically diverse study site in the southern moravia czech republic the model that considers only the derivatives with a strong relationship to colluvial soil occurrence reached 71 accuracy in colluvial area delineation while the model combining six commonly used derivatives showed less favorable results the main advantage of the method lies in a low demand of input soil data and its relatively high accuracy

a comparison of lidar based dems and usgs sourced dems in terrain analysis for knowledge based digital soil mapping abstract while lidar based digital elevation models dem are more accurate and precise than the usgs sourced dem that are widely used in soil mapping in the us their high cost and other problems prohibit an easy decision of adopting them in service oriented soil mapping conducted by a government agency like usda nrcs this study compares the performances of lidar based dem and the usgs sourced dem in calculating slope gradient as an input for knowledge based digital soil mapping kbdsm aiming to provide scientific evidence and more importantly propose a scientific approach to evaluating the two types of dem for kbdsm we conducted the comparison by evaluating how closely the dem based slope gradient values match the field measured values for a small watershed in northern vermont us we prepared three dem including a 10 m dem interpolated from the 7 5 minute usgs topographic map a 1 m dem based on lidar points and a 5 m dem resampled from the 1 m dem when calculating slope gradient we applied two neighborhood sizes 10 m and 30 m two neighborhood shapes square and circular and three slope gradient algorithms evans young horn and modified zevenbergen thorne to the three dem we then compared the calculated slope gradient values with the values measured by soil scientists at 159 sample locations in the study area statistics show that across all the tested settings the lidar based dem perform significantly better than the usgs sourced dem we conclude that lidar based dem may considerably improve the quality of inputs for kbdsm we also find that the results from the 1 m lidar based dem and the resampled 5 m dem do not show considerable and consistent differences

metallogeny of the southern sierras pampeanas argentina geological 40ar 39ar dating and stable isotope evidence for devonian au ag pb zn and w ore formation abstract early to mid paleozoic metamorphic and igneous rocks of the southern sierras pampeanas tectono stratigraphic terrane northwestern argentina host diverse metallic mineral deposits of au ni cu ag pb zn w li be nb lree and th integration of deposit geology 40 ar 39 ar geochronology and stable isotope studies with regional geological mapping and u pb zircon dating has led to the resolution of three principal metallogenic epochs ordovician intrusion hosted ni cu sulfide deposits and rare metal enriched pegmatites were succeeded by a province wide metallogenic epoch and concurrent tectonic processes during the devonian this epoch was characterized by mesothermal lode au deposits high level ag pb zn veins w cu bearing veins and replacements and various pegmatite and granite related lithophile element deposits finally miocene pliocene epithermal au ag mineralization developed during andean tectonic events sericitic alteration associated with mesothermal lode au cu ag in the sierra de las minas and sierras de cordoba yields devonian 40 ar 39 ar step heating ages in the ranges 382 393 and 351 378 ma respectively these ages span the timing of ag pb zn sulfide quartz veining in the el guaico district 386 4 ma sericite and w bearing quartz vein mineralization in the aguas de ramon and el morro districts which yielded muscovite ages of 366 1 and 363 1 ma respectively oxygen isotope 18 o smow compositions of the au ag pb zn and w ore forming fluids calculated from quartz white mica and chlorite isotope ratios range from 5 2 to 10 8 n 32 whereas calculated d smow compositions range from 61 in the la rioja au systems to 141 in the w veins n 9 sulfide 34 s values range from 1 5 to 10 0 averaging 6 5 n 15 the oxygen and hydrogen stable isotope data suggest contributions to the ore fluids of either d depleted meteoric waters that have reacted extensively with metasedimentary rocks or fluids equilibrated with degassed felsic magmas or mixtures of both this mineralization formed during and up to 20 30 ma after widespread emplacement of high level peraluminous to metaluminous granites which yielded u pb zircon ages of 404 6 382 6 ma the devonian au deposits are localised in transcurrent and reverse fault and shear zones that may be related to collision of the chilenia terrane with the western margin of gondwana during the newly defined achalian orogeny these deposits are considered to be members of the mesothermal lode au family of systems found worldwide

algorithms vs surveyors a comparison of automated landform delineations and surveyed topographic positions from soil mapping in an alpine environment abstract landform delineation has long been used in digital soil mapping to infer soil relevant information while its potential as an environmental variable in soil parameter modeling has been investigated for various automated landform delineations little research has been invested into the relationship between the delineation of landforms by algorithms based on digital terrain models dtm and the perception of landforms by the soil surveyor during field work five open source automated landform classification algorithms and a support vector machine classifier based on single terrain parameters are investigated with regard to their ability to replicate topographic position at two different scales as described by surveyors for soil profile sites in the alpine environment of south tyrol we also analyse how the variation of parameters and cell size affects the distribution of the computed landforms while a clear trend regarding grid cell size and window size can be observed with regard to the difference between macro and meso scale topographic positions the overall classification accuracy regarding the different topographic position classes was less promising although some automated classifications partly resemble the surveyor s classification a considerable number of issues remain to be investigated in order to explain the lack of reproducibility of surveyor position some of which are linked to the alpine environment of the study area these include the dominance of the backslope position the objectivity of the surveyor in rugged terrain under forest cover and the fuzzy nature of classifying topographic position especially in steep terrain by applying a forward stepwise feature selection procedure for a model based on single terrain parameters we show that at macro scale a regional terrain parameter topographic wetness index and curvatures at a coarse dtm resolution of 50 m are the most influential in distinguishing topographic position whereas at meso scale it is the topographic position index tpi with a search radius of just 70 m combined with slope gradient this study is an important first step towards consolidating topographic perception during field survey and digital terrain analysis which at least in alpine terrain still requires more investigation

quantitative topographic analysis of gilgai soil morphology abstract for a gilgai soil complex we estimated the effect of overland and intrasoil substance flows on vertisol development using concepts of topographic control of lateral substance movement by gravity rather than direct observations and measurements of these processes first we studied relationships between gilgai microtopographic characteristics and some vertisol morphological properties namely depth to parent material c and calcium carbonate enriched bca horizons secondly we checked if microtopographic characteristics of the c horizon surface influence some vertisol properties by examining the bca horizon depth we used digital models of quantitative topographic variables we concluded that the dominant mechanism controlling the c horizon depth is pedoturbation also pedoturbation can be important in the development of the bca horizons however variations in the c and the bca horizon depths are not dictated by pedoturbation only our analysis showed that key factors influencing the c and the bca horizon depths are overland and intrasoil lateral migration and accumulation of water solution and solid substances the c horizon depth depends on the landsurface topographic characteristics namely horizontal vertical and mean curvatures specific catchment area topographic and stream power indices the bca horizon depth is significantly affected by the same set of topographic attributes of both the landsurface and the c horizon surface the bca and the c horizon depths as a rule depend more on specific catchment area topographic and stream power indices than on horizontal vertical and mean curvatures of the landsurface and the c horizon surface this is because specific catchment area topographic and stream power indices take into account a relative location of a point in a microcatena utilization of quantitative topographic variables allows us to explain 82 of variation in the bca horizon depth and to suggest that topography is the main factor in the bca horizon formation

exploring lava flow hazards at pico island azores archipelago portugal pico the youngest island of the azores archipelago portugal is characterized by a central volcano and a 30 km long fissure zone its eruption rate is the highest of the azores islands with more than 35 eruptions in the last 2000 years here we estimate the lava flow hazard for pico island by combining the vent opening probability derived from the spatial distribution of eruptive fissures the classes of expected eruptions inferred from the physical and chemical characteristics of historical eruptions and the lava flow paths simulated by the magflow model the most likely area to host new eruptions is along a wnw ese trend centred on the central volcano with the highest hazard affecting the two main residential zones of lajes do pico and madalena our analysis is the first attempt to assess the lava flow hazard for pico island and may have important implications for decision making in territorial management and future land use planning

topography reconstruction of eroding landscapes a case study from a hummocky ground moraine carbozalf d abstract erosion processes aggravated by human activity have a large impact on the spatial variation of soil and topographic properties knowledge of the topography prior to human induced erosion paleotopography in naturally stable landscapes is valuable for identifying vulnerable landscape positions and is required as starting point for erosion modelling exercises however developing accurate reconstructions of paleotopography provide a major challenge for geomorphologists here we present a set of paleotopographies for a closed kettle hole catchment in north east germany 4 ha obtained through different reconstruction approaches current soil and colluvium thickness estimated from a dataset of 264 soil descriptions using ordinary kriging were used as input for a mass balance or were compared with a set of undisturbed soil thicknesses to estimate the amount of erosion the performance of the different approaches was assessed with cross validation and the count of mispredicted eroded depositional or stable landscape positions the paleotopographic reconstruction approach based on the average thickness of undisturbed soils in the study area showed the best performance this thickness 1 00 m is comparable to the average undisturbed soil thickness in the region and in line with global correlations of soil thickness as a function of rainfall and initial caco3 content the performance of the different approaches depended more on mispredictions of landscape position due to the assumption of a spatially constant initial soil depth than on small variations in this depth to conclude we mention several methodological and practical points of attention for future topography reconstruction studies concerning data quality and availability spatial configuration of data and other processes affecting topography

identification of the spatial distribution of soils using a process based terrain characterization abstract a simple process based terrain characterization model was developed to identify the occurrence of soils over a complex landscape its basic proposition is that soil distribution can be most efficiently identified by the separation of pedogeomorphological units where similar hydrological geomorphological and pedological processes occur the proposed model is a three dimensional extension of the nine unit soil landscape model the two dimensional conceptual and qualitative model is reinterpreted in terms of continuity equations describing the distribution of soil materials over hillslopes and is implemented in a geographical information system gis through the analysis of a raster digital elevation model dem the application of this model at the empire prairie in southern wisconsin usa shows a good agreement with the results of a soil investigation the difficulty in modeling the diverse geomorphological and pedological processes at low lying slope positions and the influence of relict pedological features on contemporary soil formation however remain unsolved this model can consider the spatial variability of soils both at the continuous and discrete scales and is easily transferable to other slopes in a predictive manner it is further expected to provide a quantitative tool to characterize surface topography in terms of process identification and resource survey and also a priori information for spatially distributed ecological and environmental models

the chemical composition of ree y th u rich accessory minerals in peraluminous granites of the erzgebirge fichtelgebirge region germany part i the monazite ce brabantite solid solution series peraluminous granites of the erzgebirge fichtelgebirge germany are hosts of various members of the monazite group of minerals that display an unprecedented compositional diversity the eibenstock s type granite constitutes the third reported occurrence worldwide of brabantite and the first occurrence of this mineral in a granite many new occurrences of cheralite ce as well as a monazite group mineral intermediate between monazite ce and huttonite for which the term huttonitic monazite is proposed were discovered even common monazite ce may show extreme ranges of actinide and lanthanide element concentrations the granites that host brabantite and cheralite ce are highly differentiated strongly peraluminous low temperature residual melts of s type affinity which are rich in fluorine and other volatile constituents but depleted in thorium and the light rare earth elements such highly evolved volatile rich compositions resemble rare element pegmatites and appear favorable for the precipitation of cheralite ce and brabantite but not of monazite with large amounts of huttonitic substitution instead these minerals occur preferentially in f poor biotite and f rich li mica granites of a type affinity irrespective of the level of uranium in silicate melts which may exceed that of thorium the substitution of uranium in monazite remains limited the compositional data reported here are consistent with complete miscibility in the monazite ce brabantite solid solution series under magmatic conditions these granites contain monazites that span almost the entire compositional range reported for monazite group minerals worldwide and therefore granites appear to be ideal rocks in which to study the crystal chemistry of this mineral group in general

measuring the relative topographic position of archaeological sites in the landscape a case study on the bronze age barrows in northwest belgium abstract local topography is an important parameter determining the erection of a certain type of site on a certain location in the landscape despite the importance of topography in archaeological landscape research the role of local topography has remained rather unexplored compared to other specific topographic parameters such as slope aspect curvature or visibility therefore three methods to assess the relative topographic position of sites are applied and discussed here the bronze age barrow dataset of northwest belgium acts as the subject for this methodological case study first elevation percentile calculates the area that is lower than the central point within a predetermined neighborhood secondly difference from mean elevation measures the relative topographic position of the central point as the difference between the elevation of this central point and the mean elevation within a predetermined neighborhood and finally deviation from mean elevation calculates the relative topographic position of the central point as the difference from mean elevation divided by the standard deviation of elevation within a predetermined neighborhood these three methods each with their advantages and disadvantages prove to be an added value for archaeological landscape research

the capilla del monte pluton sierras de cordoba argentina the easternmost early carboniferous magmatism in the pre andean sw gondwana margin new geochronological geochemical and isotopic data are reported for the capilla del monte two mica granite pluton in the northeastern sierras de cordoba an early carboniferous age is established by a u pb zircon concordia 336 3 ma and a rb sr whole rock isochron 337 2 ma zircon saturation geothermometry indicates relatively high temperatures 735 800 c the granites have high average sio2 74 2 na2o k2o 7 8 and high field strength elements high k2o na2o 1 7 and feo mgo ratios 5 1 with low cao content 0 71 ree patterns with marked negative eu anomalies eu eu 0 14 0 56 indicate crystal fractionation dominantly of plagioclase and k feldspar from a peraluminous magma enriched in f isotope data 87sr 86srinitial 0 7086 e nd336 5 5 to 4 4 with t dm 1 5 ga zircon e hf336 0 8 to 6 1 mean t dm 1 5 ga suggest a mesoproterozoic continental source albeit with some younger or more juvenile material indicated by the hf data the pluton is the easternmost member of a carboniferous a type magmatic suite which shows an increase in juvenile input toward the west in this part of the pre andean margin the petrological and geochemical data strongly suggest a similar intraplate geodynamic setting to that of the nearby but much larger late devonian achala batholith although hf isotope signatures of zircon suggest a more uniformly crustal origin for the latter further studies are required to understand whether these bodies represent two independent magmatic episodes or more continuous activity

predicting regolith properties using environmental correlation a comparison of spatially global and spatially local approaches abstract in this paper we assess the utility of mapping regolith properties as continuously varying fields using environmental correlation over large spatial areas the assessment is based on a comparison of results from spatially global and local analysis methods the two methods used are a feed forward back propagation neural network applied globally and moving window regression applied locally these methods are applied to five regolith properties from a field site at weipa queensland australia the properties considered are the proportions of oxides of aluminum iron silica and titanium present in samples as well as depth to the base of the bauxite layer these are inferred using a set of surface measurable features consisting of landsat data geomorphometric indices and distances from streams and swamps the moving window regression results show a much stronger relationship than do those from the spatially global neural networks the implication is that the scale of the analysis required for environmental correlation is of the order of hundreds of metres and that spatially global analyses may incur an automatic reduction in accuracy by not modelling geographically local relationships in this case this effect is up to 45 error at a tolerance near half of a standard deviation

digital terrain modeling abstract this article examines how the methods and data sources used to generate dems and calculate land surface parameters have changed over the past 25 years the primary goal is to describe the state of the art for a typical digital terrain modeling workflow that starts with data capture continues with data preprocessing and dem generation and concludes with the calculation of one or more primary and secondary land surface parameters the article first describes some of ways in which lidar and radar remote sensing technologies have transformed the sources and methods for capturing elevation data it next discusses the need for and various methods that are currently used to preprocess dems along with some of the challenges that confront those who tackle these tasks the bulk of the article describes some of the subtleties involved in calculating the primary land surface parameters that are derived directly from dems without additional inputs and the two sets of secondary land surface parameters that are commonly used to model solar radiation and the accompanying interactions between the land surface and the atmosphere on the one hand and water flow and related surface processes on the other it concludes with a discussion of the various kinds of errors that are embedded in dems how these may be propagated and carried forward in calculating various land surface parameters and the consequences of this state of affairs for the modern terrain analyst

comparing data driven landslide susceptibility models based on participatory landslide inventory mapping in purwosari area yogyakarta java there are different approaches and techniques for landslide susceptibility mapping however no agreement has been reached in both the procedure and the use of specific controlling factors employed in the landslide susceptibility mapping each model has its own assumption and the result may differ from place to place different landslide controlling factors and the completeness of landslide inventory may also affect the different result incomplete landslide inventory may produce significance error in the interpretation of the relationship between landslide and controlling factor comparing landslide susceptibility models using complete inventory is essential in order to identify the most realistic landslide susceptibility approach applied typically in the tropical region indonesia purwosari area java which has total 182 landslides occurred from 1979 to 2011 was selected as study area to evaluate three data driven landslide susceptibility models i e weight of evidence logistic regression and artificial neural network landslide in the study area is usually affected by rainfall and anthropogenic activities the landslide typology consists of shallow translational and rotational slide the elevation slope aspect plan curvature profile curvature stream power index topographic wetness index distance to river land use and distance to road were selected as landslide controlling factors for the analysis considering the accuracy and the precision evaluations the weight of evidence represents considerably the most realistic prediction capacities 79 when comparing with the logistic regression 72 and artificial neural network 71 the linear model shows more powerful result than the nonlinear models because it fits to the area where complete landslide inventory is available the landscape is not varied and the occurence of landslide is evenly distributed to the class of controlling factor

landform pattern recognition and classification for predicting soil types of the uasin gishu plateau kenya abstract information obtained from landform classification is fundamental for understanding physical chemical and biological soil processes digital elevation models dems can be used for landform classification using a geomorphic pattern recognition and classification approach such as geomorphons in this study we used geomorphons to predict soil types of the uasin gishu plateau in western kenya with the aim of improving the existing soil type maps we ran the geomorphons classification on the 30 m shuttle radar topographic mission srtm dem using the module r geomorphons add on in grass gis with look up distance l values of 10 20 30 40 50 60 70 80 90 and 100 cells 300 m to 3 000 m and flatness threshold values of 2 0 5 and 0 01 degrees we grouped the resulting geomorphons into three classes upland summits upland midslopes and bottomlands we then assigned soil types according to the world reference base soil classification system to these three landscape positions after dividing the study area into the lower plateau and the upper plateau based on elevation and geomorphology the predicted soil types were quantitatively evaluated against 50 soil point observations based on overall accuracy precision recall and cohen s kappa coefficient k metrics evaluation results showed that an l value of 20 cells performed best k 0 52 overall accuracy 0 62 followed by an l value of 30 cells k 0 50 overall accuracy 0 58 l values of 60 70 and 80 cells performed worse k 0 35 overall accuracy 0 48 although an l value of 20 cells performed slightly better than an l value of 30 cells the l value of 30 cells better captured the geomorphology and soil landscape relationships based on our own expert knowledge legacy data and the fact that the bottomlands pattern was more continuous for an l value of 30 cells than for an l value of 20 cells upland summits occurred over 32 of the plateau and were occupied by nitisols on the upper plateau and ferralsols on the lower plateau upland midslopes occurred over 42 of the plateau and were occupied by acrisols on the upper plateau and acrisols ferralsols on the lower plateau bottomlands occurred over 26 of the plateau and were occupied by luvisols gleysols on both the upper and lower plateau geomorphons as a method of landform classification correlated to geomorpho pedological processes and captured soil variations and differences in the study area the approach is computationally efficient and can be used for large areas but is limited in that it only classifies landscapes according to shape this means that the algorithm does not separate or identify soil types with different parent materials occurring within one landform class thus regosols and cambisols on very steep slopes and acrisols and ferralsols on gentle slopes could not be separated

capelinhos 1957 1958 faial azores deposits formed by an emergent surtseyan eruption the 1957 1958 eruption of capelinhos faial island azores involved three periods of surtseyan hydromagmatic activity two in 1957 and one in 1958 deposits from this eruption are exposed both in sea cliffs cut into the flanks of the tuff cone and more distally 1 km from the vent five lithofacies are identified lithofacies i is composed of even thickness beds with laterally continuous internal stratigraphy and is interpreted to have been formed by fallout lithofacies ii consists of beds with internally discontinuous lenses and has sand wave structures that increase in abundance toward the outer margins of the tuff cone this lithofacies is interpreted as having been deposited from pyroclastic surges lithofacies iii is composed of mantle bedded deposits with laterally discontinuous internal stratigraphy this lithofacies is interpreted to have been formed by hybrid processes where fallout of tephra occurred simultaneously with pyroclastic surges in the outer flanks of the tuff cone lithofacies iii grades laterally into fallout beds of lithofacies i lithofacies iv consists of alternating beds of coarse ash aggregates and non aggregated fine ash and is particularly well developed in distal regions some of this facies was formed by fallout alternating beds also occur plastered against obstacles up to 2 km from the vent indicating an origin from wet pyroclastic surges the orientation of plastered tephra indicates that the surges were deflected by topography as they decelerated the distinction between surge and fallout in distal regions is uncertain because wind drifted fallout and decelerating surge clouds can generate similar deposits lithofacies v consists of scoria lapilli beds interpreted to be fallout from hawaiian style fire fountaining in the later stages of the eruption juvenile pyroclasts within hydromagmatic deposits are predominantly poorly vesicular 25 60 of clasts 30 vesicles however on both micro and macroscopic scales there is a wide range in clast vesicularity up to 70 vesicles indicating that although fragmentation was predominantly hydromagmatic vesiculation and magmatic volatile driven fragmentation operated simultaneously

mean curvature watersheds a simple method for segmentation of a digital elevation model into terrain units abstract terrain segmentation is the process of subdividing a continuous terrain surface into discrete terrain units if the resulting units represent meaningful geomorphic objects the approach may facilitate studies of not only landforms and land forming processes but also the interaction among surface form soil vegetation hydrology and topoclimatic regimes commonly used methods for terrain segmentation fail to produce terrain units with a potentially large but cyclic variation in topographic attributes such as uniformly curved areas bounded by topographic break lines although this topographic characterisation is common for a number of landforms this paper describes a new method for terrain segmentation using mean curvature mec watersheds the method produces objects that contain a cycle of mec values thus the topographic variation within each object may be large but due to the cyclic nature of the mec variation a geometric simplicity is ensured in a case study we show how the resulting terrain units correspond well with a number of landforms and surface types observed in the field and conclude that the method can be expected to be of great value for a number of applications within geomorphology and related disciplines

terrain controls on depressional soil distribution in a hummocky morainal landscape in hummocky morainal landscapes soil distribution in well drained landscape positions tends to follow a consistent pattern soils in depressions however are more difficult to predict reliably this study had two objectives 1 to determine the parent material and landscape properties controlling the formation of the different depressional soils and 2 to use these controls to identify quantitative terrain based predictors of soil type in depressions only two terrain attributes specific dispersal area sda and elevation relative to open water bodies were required to distinguish three main soil groups gley recharge non gley recharge and discharge soils specific dispersal area is the downslope area draining flow from a given grid cell gley recharge soils occur primarily at points with sda of less than 2 m2 m 1 regardless of elevation within a given site because most of the runoff flowing to a point with very low sda values will pond or infiltrate vertically rather than flow downslope non gley recharge soils and discharge soils both occur at points with sda of greater than 2 m2 m 1 the majority of the non gley recharge soils occur above 5 m elevation relative to an open water body and the majority of the discharge soils occur below 5 m elevation relative to an open water body reflecting the importance of solute cycling in the development of discharge conditions buried and depositional soils could not be predicted from current terrain attributes because their profile characteristics were derived from the paleosurface

flow and deposition of pyroclastic granular flows a type example from the 1975 ngauruhoe eruption new zealand small volume pyroclastic density currents pdcs are generated frequently during explosive eruptions with little warning assessing their hazard requires a physical understanding of their transport and sedimentation processes which is best achieved by the testing of experimental and numerical models of geophysical mass flows against natural flows and or deposits to this end we report on one of the most detailed sedimentological studies ever carried out on a series of pristine small volume pdc deposits from the 1975 eruption of ngauruhoe volcano whose emplacement were also witnessed during eruption using high resolution gps surveys a series of lateral excavations across the deposits and bulk sedimentological analysis we constrained the geomorphology internal structure and texture of the deposits with respect to laterally varying modes of deposition deposition from these pdcs began only on slopes at or around the material s angle of repose c 30 in unconfined settings the granular pdcs are interpreted to have been quasi steady forming sheets and lobes around the angle of repose where flows were confined sheet like proximal facies made up around 10 of the deposit volume at the angle of repose but 90 of the material was deposited from apparently unsteady inertial granular pdcs as a distal levee and channel facies on slopes well below the repose angle hence confined pdcs were able to travel up to 50 farther than unconfined flows in the distal facies the deposit width is inversely correlated to the local slope and the height of the levees above the deposit centreline is positively correlated with slope internally the deposits comprise three parts a coarse grained fines free sole layer that laterally connects to levees zone i an ashy matrix supported central body zone ii and an overlying coarse plaster of clasts zone ii trends in grain size data suggests these zones derive from a continuous un mixing of coarse particles from the initial bulk material by granular segregation that preferentially drives large particles to the upper free surface of the flow where they are concentrated at the front of flow before being deposited and overrun by comparison to analogue experiments we suggest a model of flow and deposition where the temporally and spatially varying mode of deposition is determined by the flow velocity the local slope the vertical velocity gradient the velocity gradient at the free surface and the vertical deposition rate using this model estimated vertical deposition rates of c 5 cm s 1 from the ngauruhoe pdcs agree with those determined in laboratory experiments on inertial granular flows

sediment connectivity in the high alpine valley of val muschauns swiss national park linking geomorphic field mapping with geomorphometric modelling abstract the efficiency of sediment routing through mountain sediment cascades is controlled by the connectivity of hillslopes to the main river system a lack of connectivity may cause long term sediment storage and exclude large fractions of a basin from the sediment routing for several thousand years here we studied sediment dynamics in a small formerly glaciated valley in the swiss alps to characterise the sediment connectivity to the stream we calculated a morphometric index using a gis algorithm the modelling results were tested against a field based geomorphic mapping of sediment storages which were evaluated with respect to their state of de coupling in accordance to the field diagnostics the modelling results indicate very well that the present day sediment flux is conditioned by the glacial valley morphometry inherited through pleistocene glaciation especially in the upper hanging valleys the connectivity index is reduced noticeably due to the glacial cirque morphology based on the field mapping 30 of the hillslope sediment cascades are interrupted and 20 of the storage boundaries are currently affected by a lack of material transfer as a consequence 29 of the basin surface is currently disconnected from the main river nevertheless the gis algorithm overestimates the connectivity within the basin because it fails to calculate decoupling between neighbouring pixels in digital terrain models dtms around 35 of the basin surface which has been mapped in the field as being decoupled is related to relative high connectivity our study highlights the potential of morphometric gis modelling for studying sediment connectivity but additionally emphasises the indispensability of geomorphic field mapping for a holistic understanding of mountain cascading systems

soil variation within a hummocky podzolic landscape under intensive potato production abstract the purpose of this study was to determine if relationships between landscape position and soil properties occurred on a podzolic landscape with hummocky meso topography which is under intensive potato production in new brunswick canada elevation was measured on an approximately 5 m grid spacing and used to construct a digital elevation model selected soil textural morphological and chemical properties were measured on a 7 17 grid with 25 m spacing landform segmentation was used to divide sampling locations into eight landform elements based on profile and plan curvature slope gradient and specific dispersal area orthic humic regosols and orthic sombric brunisols were predominant in upper slope positions whereas gleyed subgroups of the main soil orders were commonly found in the concave lower slope positions lower concave slope positions generally had lesser sand and coarse fragment contents greater silt organic carbon and 137 cs contents and greater depth to c horizon and to bedrock than upper convex slope positions in contrast a horizon thickness clay content soil ph and soil test p showed little relationship to landscape position landform segmentation was effective in characterizing the spatial distribution of soil loss at the study site as indicated based on 137 cs content and of soil taxa however the resulting landform elements had generally small differences in parameters such as soc sand silt and clay content which are commonly considered important in agricultural production the landscape examined in this study appears to be dominated by soil loss and the closely related homogenizing effects of intensive tillage for potato production the properties that continue to show a clear relationship to landform position are largely remnant properties e g depth to bedrock or to the c horizon whose pattern reflects a stronger hydrological and or pedological control the results provide further evidence that human induced changes in soil can fundamentally alter the natural pattern of soil distribution in the landscape even over relatively short i e 100 years time scales

u pb th pb and ar ar geochronology from the southern sierras pampeanas argentina implications for the palaeozoic tectonic evolution of the western gondwana margin

water flow in a hummocky landscape in central saskatchewan canada i distribution of water and soils abstract water flow in a hummocky landscape is highly variable in time and space the purpose of the study is to use a classification system based on landscape surface form to delineate areas with similar hydrologic properties the study was conducted in a hummocky landscape with a closed drainage pattern in the black soil zone of saskatchewan the sites consisted of three closed drainage basins 80 150 m across surrounding individual temporary sloughs the distribution of water in the landscape was inferred from in situ electrical conductivity and soil morphological properties including thickness of a and eluviated horizons and depth to calcium carbonate in situ electrical conductivity was strongly correlated with the depth of water in the top 1 2 m of the soil the sites were divided on the basis of landscape surface form into lower slope upper slope and saddle positions which accounted for 30 50 and 20 of the cultivated areas of the basins respectively the lower slope positions were well leached of soluble salts and had high water contents thick a horizons gleyed and or eluviated horizons and thick zones of calcium carbonate depletion the upper slope positions had limited leaching of soluble salts low water contents thin a horizons lacked eluviated horizons and calcium carbonate was present either at shallow depths or at the soil surface the properties of the saddle positions were intermediate between the upper and lower slope positions the spatial distribution of water in the landscape persisted over time due to the redistribution of water in the landscape by topography

discovery of a plinian basaltic eruption of roman age at etna volcano italy basaltic plinian eruptions are rare and poorly known volcanic phenomena etna is an active basaltic volcano the activity of which is dominated by effusive eruptions that represent a continuous threat to a large populated area we report on a plinian eruption of basaltic composition that occurred in 122 b c lapilli fallout caused extensive damage to the southern flank of the volcano the discovery of this large explosive eruption raises important issues for previous hazard assessment at etna and other basaltic volcanoes an effusive basaltic volcano generally nonhazardous for humans can become very dangerous

na fe ca alteration and lree th nb mineralization in marble andgranitoids of sierra de sumampa santiago del estero argentina the jasimampa area in the sierra de sumampa de santiago del estero argentina contains light rare earth element lree th nb mineralization associated with several stages of carbonates and widespread fenitization of marble granite 496 2 9 ma and alkaline and siliceous igneous comendite dikes u pb zircon age of 390 ma derived from fractionation of oceanic island basalts this is the third discovery of lree mineralization in argentina and marks a new alkaline intracontinental magmatic event of devonian age albite ab 97 99 aegirine ae 70 92 ja 1 11 q 6 19 hematite mg arfvedsonite fluorine rich apatite and late ca fe mn carbonates monazite pyrochlore overprint and crosscut granite and comendite outcrops in a 15 km 2 area locally the na rich assemblage is pervasive and results in total destruction of host rocks na fe metasomatism near granite and comendite produced aegirine ae 86 91 ja 1 8 q 6 11 mg arfvedsonite and minor albite ab 98 99 in adjacent marble with multiple stages of late ca mn mg fe carbonates associated with iron and manganese oxides hematite and traces of sulfides sphalerite pyrite galena monazite ce is the main lree bearing mineral and occurs with minor ferrocolumbite pyrochlore strontiopyrochlore and apatite associated with a second generation of fine grained hematite barite and celestine structural controls on na fe ca alteration and lree mineralization in granitoid and marble protoliths include brittle ductile shear zones brittle fracture systems and a series of monolithologic and heterolithologic breccias with hydrothermal aegirine carbonate and chalcedony matrices that occur at granite marble comendite contacts fragments of multiple breccia types within breccias indicate multiple episodes of brecciation alteration and mineralization the fluid responsible for early fenitization of granite and comendite was aqueous carbonic with co 2 of relatively high density between 0 85 and 0 95 g cm 3 salinity near 9 wt percent nacl equiv and minimum temperatures in the range of 250 to 280 c pervasively altered comendite and granite have high total ree content 1 750 ppm and 2 126 ppm respectively mainly lree early banded and mottled aegirine arfvedsonite replacements of marble have high absolute ree abundance 2 513 4 663 ppm compared to the least altered marble 476 ppm subsequent hydrothermal stages with carbonates hematite pyrolusite monazite and subordinate celestine and barite caused alteration of marble that was accompanied by an increase in absolute ree abundance up to 15 45 wt percent and high sr 10 5 wt th 4 390 ppm and ba 1 8 wt alteration and mineralization at jasimampa are the result of late stage carbonatitic magma fractionation and fluid exsolution this is indicated by the strongly alkaline character of early alteration the composition of the hydrothermal carbonates apatite and lree sr and ba rich minerals the chondrite normalized ree patterns showing strong lree enrichment without an eu anomaly and the replacement of marble by assemblages with very high ba th lree and sr and strong k zr and ti depletions the alteration style and mineralization at jasimampa are similar to the giant fe lree nb deposit bayan obo and other hydrothermal lree deposits hosted in carbonatites of china

geomorphons a pattern recognition approach to classification and mapping of landforms abstract we introduce a novel method for classification and mapping of landform elements from a dem based on the principle of pattern recognition rather than differential geometry at the core of the method is the concept of geomorphon geomorphologic phonotypes a simple ternary pattern that serves as an archetype of a particular terrain morphology a finite number of 498 geomorphons constitute a comprehensive and exhaustive set of all possible morphological terrain types including standard elements of landscape as well as unfamiliar forms rarely found in natural terrestrial surfaces a single scan of a dem assigns an appropriate geomorphon to every cell in the raster using a procedure that self adapts to identify the most suitable spatial scale at each location as a result the method classifies landform elements at a range of different spatial scales with unprecedented computational efficiency a general purpose geomorphometric map an interpreted map of topography is obtained by generalizing allgeomorphons to a small number of the most common landform elements due to the robustness and high computational efficiency of the method high resolution geomorphometric maps having continental and even global extents can be generated from giga cell dems such maps are a valuable new resource for both manual and automated geomorphometric analyses in order to demonstrate a practical application of this new method a 30 m cell 1 geomorphometric map of the entire country of poland is generated and the features and potential usage of this map are briefly discussed the computer implementation of the method is outlined the code is available in the public domain

structure and eruptive mechanisms at surtsey volcano iceland glassy basalt tuff was the primary material cored in 1979 from a 181 m deep drill hole on the east tuff ring of surtsey volcano despite the fact that the hole extends 122 m below sea level all the core is similar to the exposed tephra composing the two tuff rings of the island the tuff includes abundant accretionary lapilli and tuff vesicles indicating that it was all deposited subaerially during the growth of the tuff rings repeated hydromagmatic explosion cycles began with a series of intermittent tephra finger explosions leading up to continuous uprush explosions which lasted for several minutes to several hours this nozzle like continuous activity produced eruption columns 100 250 m in diameter and 500 2000 m in height which probably quarried several hundred metres below the ground surface the continuous uprush explosion type provides a reasonable mechanism to excavate a diatreme from the top down during construction of the tuff rings concentric faults repeatedly downdropped a funnel like structure 400 800 m in diameter several hundred metres thus accounting for the presence of subaerially deposited tephra in the drill core far beneath sea level ring dykes later intruded upward along these faults and fed small lava flows heat in the surface tephra probably originated primarily from these shallow intrusions