large scale dam removal on the elwha river washington usa river channel and floodplain geomorphic change abstract a substantial increase in fluvial sediment supply relative to transport capacity causes complex large magnitude changes in river and floodplain morphology downstream although sedimentary and geomorphic responses to sediment pulses are a fundamental part of landscape evolution few opportunities exist to quantify those processes over field scales we investigated the downstream effects of sediment released during the largest dam removal in history on the elwha river washington usa by measuring changes in riverbed elevation and topography bed sediment grain size and channel planform as two dams were removed in stages over two years as 10 5 million t 7 1 million m3 of sediment was released from two former reservoirs downstream dispersion of a sediment wave caused widespread bed aggradation of 1 m greater where pools filled changed the river from pool riffle to braided morphology and decreased the slope of the lowermost river the newly deposited sediment which was finer than most of the pre dam removal bed formed new bars largely pebble granule and sand material prompting aggradational channel avulsion that increased the channel braiding index by almost 50 as a result of mainstem bed aggradation floodplain channels received flow and accumulated new sediment even during low to moderate flow conditions the river system showed a two to tenfold greater geomorphic response to dam removal in terms of bed elevation change magnitude than it had to a 40 year flood event four years before dam removal two years after dam removal began as the river had started to incise through deposits of the initial sediment wave 1 2 million t of new sediment 10 of the amount released from the two reservoirs was stored along 18 river km of the mainstem channel and 25 km of floodplain channels the elwha river thus was able to transport most of the released sediment to the river mouth the geomorphic alterations and changing bed sediment grain size along the elwha river have important ecological implications affecting aquatic habitat structure benthic fauna salmonid fish spawning and rearing potential and riparian vegetation the response of the river to dam removal represents a unique opportunity to observe and quantify fundamental geomorphic processes associated with a massive sediment influx and also provides important lessons for future river restoration endeavors

developments in monitoring and modelling small scale river bed topography recent research in fluvial geomorphology has emphasized the spatially distributed feedbacks amongst river channel topography flow hydraulics and sediment transport although understanding of the behaviour of dynamic river channels has been increased markedly through detailed within channel process studies less attention has been given to the accurate monitoring and terrain modelling of river channel form using three dimensional measurements however such information is useful in two distinct senses firstly it is one of the necessary boundary conditions for a physically based deterministic modelling approach in which three dimensional topography and river discharge drive within channel flow hydraulics and ultimately spatial patterns of erosion and deposition and therefore channel change secondly research has shown that an alternative means of estimating the medium term bedload transport rate can be based upon monitoring spatial patterns of erosion and deposition within the river channel this paper presents a detailed assessment of the distributed monitoring and terrain modelling of river bed topography using a technique that combines rigorous analytical photogrammetry with rapid ground survey the availability of increasingly sophisticated terrain modelling packages developed for civil engineering application allows the representation of topographic information as a landform surface intercomparison of landform surfaces allows visualization and quantification of spatial patterns of erosion and deposition a detailed assessment is undertaken of the quality of the morphological information acquired this allow some general comments to be made concerning the use of more traditional methods to monitor and represent small scale river channel morphology

new views of lunar geoscience an introduction and overview beyond the earth the moon is the only planetary body for which we have samples from known locations the analysis of these samples gives us ground truth for numerous remote sensing studies of the physical and chemical properties of the moon and they are invaluable for our fundamental understanding of lunar origin and evolution prior to the return of the apollo 11 samples the moon was thought by many to be a primitive undifferentiated body e g urey 1966 a concept shattered by the data returned from the apollo and luna missions ever since new data have helped to address some of our questions but of course they also produced new questions in this chapter we provide a summary of knowledge about lunar geologic processes and we describe major scientific advancements of the last decade that are mainly related to the most recent lunar missions such as galileo clementine and lunar prospector 1 1 the moon in the planetary context compared to terrestrial planets the moon is unique in terms of its bulk density its size and its origin fig 1 1a c all of which have profound effects on its thermal evolution and the formation of a secondary crust fig 1 1d numerous planetary scientists considered the moon as an endmember among the planetary bodies in our solar system because its lithosphere has been relatively cool rigid and intact throughout most of geological time a one plate planet and its surface has not been affected by plate recycling an atmosphere water or life therefore the moon recorded and preserved evidence for geologic processes that were active over the last 4 4 5 b y and offers us the unique opportunity to look back into geologic times for which evidence on earth has long been erased fig 1 1c d impact cratering an exterior process is considered the most important surface process on the moon internal

apollo 16 impact melt sheets contrasting nature of the cayley plains and descartes mountains and geologic history apollo 16 stations 4 and 5 rake samples were examined petrographically and by electron microprobe and inaa results were combined with published information major and trace element compositions petrologic information and age determinations for nonrake samples from stations 4 and 5 and some other apollo 16 sample localities lithologic abundances support the idea korotev 1981 that the variation of soil compositions at apollo 16 is a result of mixing between a component represented by station 5 soil and components much like either the dimict breccias station 4 soils or feldspathic fragmental breccias stations 1 2 and 11 in composition dimict breccias because of their restricted occurrence are apparently not a constituent of either the cayley or descartes formations they were contributed to the surface materials by south ray crater and were probably excavated from beneath both formations by this event pyroxene olivine and coexisting plagioclase compositions from within the anorthosite portions of dimict breccias bridge the gap between the mg rich and ferroan anorthosite fields analyses from associated cumulate and granulitic clasts indicate that they are the source of the intermediate material dimict breccia anorthosites are thus polymict rocks not pristine ferroan anorthosite compositions of apollo 16 impact melt rocks suggest a number of compositional clusters discriminant and cluster analyses of compositional data confirm the existence and strength of these clusters as do age determinations and ir au ratios within each group each of three clusters represents an impact event in the apollo 16 region petrologic information and age determinations indicate that dimict breccias formed approximately 3 92 b y ago the nectaris event occured between 3 84 and 3 92 b y ago and the cayley plains were deposited as a result of the imbrium event sometime later than 3 84 b y

three dimensional reconstruction of fluvial surface sedimentology and topography using personal mobile laser scanning high resolution quantification of fluvial topography has been enabled by a number of geomatics technologies hyperscale surveys with spatial extents of 1 km2 have been widely demonstrated by means of terrestrial laser scanning tls and structure from motion sfm photogrammetry recent advances in the development and integration of global navigation satellite system gnss inertial measurement unit imu and lightweight laser scanning technologies are now resulting in the emergence of personal mobile laser scanners mls that have the potential to increase data acquisition and processing rates by 1 2 orders of magnitude compared to tls sfm and thus challenge the recent dominance of these technologies this investigation compares a personal mls survey using a leica pegasus backpack that integrates velodyne puck vlp 16 sensors and a multi station static tls survey using a riegl vz 1000 scanner to produce digital elevation models dems and surface sedimentology maps the assessment is undertaken on a 500 m long reach of the braided river feshie comparison to 107 independent real time kinematic rtk gnss check points resulted in similar mean error me and standard deviation error sde for tls me 0 025 m sde 0 038 m and personal mls me 0 014 m sde 0 019 m direct cloud to cloud c2c comparison between a sample of tls and personal mls observations 2 8 million points revealed that c2c distances follows a sharply decreasing burr distribution a 2 35 b 3 19 rate parameter s 9 53 empirical relationships between sub metre topographic variability and median sediment grain size 10 100 mm demonstrate that surface roughness from personal mls can be used to map median grain size differences between tls and personal mls empirical relationships suggest such relationships are dependent on survey technique personal mls offers distinct logistical advantages over sfm photogrammetry and tls for particular survey situations and is likely to become a widely applied technique

a ferroan region of the lunar highlands as recorded in meteorites mac88104 and mac88105 macalpine hills 88104 and 88105 mac88104 5 are paired meteorites of noritic anorthosite composition from the lunar highlands mac88105 is a breccia composed mainly of melt breccia clasts in a fine grained fragmental and partly glassy matrix the most abundant melt lithologies are feldspathic and are similar in composition to the bulk meteorite other melt lithologies include feldspathic melt rocks mafic melt breccias and a rare melt breccia relatively enriched in incompatible trace elements subordinate lithic clasts are granulitic breccias and ferroan relatively low mg mg fe igneous lithologies including troctolitic anorthosite anorthositic norite gabbronorite and anorthosite igneous clasts having mafic mineral compositions more magnesian than fo55 and en60 were not observed rare fragments of glass spheres and shards as well as glass clasts indicate that the meteorite was derived from an immature regolith the bulk composition of mac88105 is characterized by a molar mg mg fe ratio of 0 62 at the extreme low end of the range for meteorites from the lunar highlands its low concentrations of incompatible trace elements and feldspathic bulk composition 29 al2o3 suggest that it like the other lunar meteorites formed at a site far removed from the areas sampled by the apollo missions similarities in mineral compositions among the different lithologies of the breccia melt breccia clasts granulitic breccias igneous fragments and the distribution of mineral fragments suggest that most components of the meteorite were derived from a crustal section dominated by material with a noritic anorthosite composition and an affinity to the ferroan suite of plutonic rocks the mafic melt breccias have roughly peritectic melt compositions similar to many low k fra mauro melt breccias in the apollo collection but much more ferroan and represent a source material distinct from the noritic anorthosite moderate ce anomalies both positive and negative occur in some separated clasts and to a lesser extent in some small chips dominated by matrix but not in powder prepared from 20 g of bulk meteorite these anomalies are almost certainly terrestrial weathering effects one granulitic breccia clast is rich in siderophile elements as a result of a large amount of fe ni metal the auir ratio of the clast 0 64 ci normalized is distinctly different from that of metal rich impact melts from apollo 16 3 ci normalized the compositional range observed among the nonmare lunar meteorites alha81005 y791197 y82192 3 y86032 and mac88104 5 is equivalent to that observed among representative samples of 1 mm fines from apollo 16 thus compositional data provide little constraint on the number of impacts required to eject these meteorites from the moon

rapid incision of a small coarse and steep fan delta in response to base level fall the case of nahal qedem the dead sea israel the dead sea has been continuously dropping 0 4 1 0 m yr 1 since the middle of the 20th century and thus provides a unique field laboratory for studying in real time the response of drainage systems to a non tectonic base level fall the aim of this work is to study the short term ongoing erosive response to a rapid base level drop in a small steep fronted erodible fan delta setting the work explores the controls of the steep qedem fan delta guided by its clinoform structure on its incision longitudinal profiles of the fan delta and of its entrenched channel were measured in the field sedimentary facies changes fluviatile shallow lacustrine and beach were followed along exposures the existence of large boulders provided an opportunity to examine the uncertain role of armouring and boulder flux on incision the field study was combined with digital elevation models dems that were extracted from pairs of overlapping aerial photos maps of erosion and deposition were prepared using a change detection algorithm the longitudinal profile of the entrenched channel was found to be steep and linear the outlet temporarily hangs elevated and ungraded above the retreating lake level indicating years without incision flow events which cause lags in response to the rapid lake level drop in spite of the large boulders the small drainage basin and precipitation volume over the basin of the qedem the recorded vertical incision rates in the unconsolidated sediments are as high as 0 8 m yr 1 i e similar to those of the largest wadis draining to the dead sea the steep front of the fan delta is suggested to be a main factor controlling the efficient incision a unique transport mechanism of rolling boulders following undercutting contributed to the entrenchment efficiency copyright 2010 john wiley sons ltd

the case for an imbrium origin of the apollo thorium rich impact melt breccias abstract mafic th rich impact melt breccias most of which are identified with the composition known as low k fra mauro lkfm are the most common rock type in the nonmare regoliths of the apollo lunar landing sites the origin of mafic impact melt breccias bears on many lunar problems the nature of the late meteoroid bombardment cataclysm the spatial distribution of kreep both near the surface and at depth the ages of the major basins and the composition of the early crust of the nearside lunar highlands thus it is crucial that the origin of mafic impact melt breccias be accurately understood because of both intra and intersite differences in compositions of mafic impact melt breccia samples apparent differences in crystallization age and differences in siderophile element ratios previous studies have argued that either 1 most mafic impact melt breccias are the products of several large craters local to the site at which they were found but that some are of basin origin or that 2 they are all from the imbrium apollos 14 and 15 nectaris apollo 16 and serenitatis apollo 17 basins here we reconsider the hypothesis that virtually all of the th rich mafic impact melt breccias from the apollo missions are products of the imbrium impact ejecta deposit modeling based on modern crater scaling indicates that the imbrium event produced ejecta deposits that average hundreds of meters thick or more at all apollo highland sites which is thicker than some previous estimates substantial amounts of imbrium ejecta should have been sampled at every apollo highland site we suggest that the mafic impact melt breccias may be the principal form of those ejecta the imbrium projectile impacted into th rich material that we regard as part of a unique mafic lunar geochemical province we call the high th oval region based on the surface distribution of th only basins within the high th oval region excavated th rich material the th concentrations of the highlands as observed by the apollo orbiting ray experiments are consistent with the estimates from ejecta modeling of the younger basin forming impacts only imbrium was large enough to produce the copious amount of melt required by the ubiquitous presence of mafic impact melt breccias in the apollo sampled regolith the high th oval region still may have been molten or hot at shallow depths 4 ga ago when the imbrium projectile struck we reason that compositional heterogeneity of ejected melt breccia is to be expected under these circumstances we argue that siderophile element fingerprints of mafic impact melt breccias are not inconsistent with production of all common types by a single projectile we suggest that the narrow range of ages of 3 7 4 0 ga for all successfully dated mafic impact melt breccias may reflect a single event whose age is difficult to measure precisely rather than a number of discrete impact events closely spaced in time such that reported age variations among mafic impact melt breccias reflect the ability to measure 40ar 39ar ages with greater precision than the accuracy with which measured portions of mafic impact melt breccias have recorded the time of their formation

monitoring sediment source areas in a debris flow catchment using terrestrial laser scanning abstract geomorphic changes caused by three debris flow events in a small mountain catchment moscardo torrent eastern italian alps were investigated by means of multitemporal terrestrial laser scanning tls surveys over three areas exposed to debris flow dynamics for these areas dem of differences dods with a 0 2 m spatial resolution allowed the assessment of elevation uncertainty as spatially variable by applying the fuzzy inference system fis proposed by wheaton et al 2010 along with two commonly used parameters affecting digital elevation model dem accuracy such as terrain slope and point density we developed and employed in the fis a new index named vegetation noise that takes into account the disturbance caused by the vegetation cover on the dem accuracy the results of volumetric budgets of the surveyed sediment source areas derived from the dod analysis were compared with debris flow volumes estimated from flow stage measurements at the instrumented channel reach on the one hand the discrepancies arising from this comparison underline the limitations of tls surveys over morphologically complex areas such as debris flow catchments on the other hand the tls unveils the geomorphic changes at the scale of the single event because a terrestrial survey is usually easier to carry out than an aerial one the analysis of dem quality and uncertainty indexes correlation may help to refine methods for spatializing elevation errors and improving the reliability of the models

the development of an automated correction procedure for digital photogrammetry for the study of wide shallow gravel bed rivers this paper develops an automated correction procedure for dealing with point errors associated with through water photogrammetry for application in the study of clear water shallow gravel bed rivers the procedure involves combining digital photogrammetry and image analysis techniques to i correct for the effects of refraction at an air water interface and ii eliminate and reinterpolate points where the bed has not been seen the correction procedure was applied to raw digital elevation models dems generated using digital photogrammetry from 1 3000 scale aerial photography of a small reach of the north ashburton river new zealand the accuracy of corrected and uncorrected dems is evaluated using an independent data set a measure of geomorphological usefulness as well as dem external reliability is obtained from calculations of water depth distributions and mean bed level results show that digital photogrammetry used in conjunction with image analysis techniques can successfully be used for extracting high resolution dems of gravel river beds in exposed areas errors are small and random tending to cancel out over large numbers of points where water is shallow and following correction point elevation errors are statistically no different from those for exposed zones in deeper water despite an improvement following application of the correction procedure elevation errors scale with water depth the geomorphological potential of photogrammetric survey of large gravel river beds is demonstrated by the ease and accuracy of calculations of water depth distribution important for the assessment of a river s ecological and recreational characteristics and mean bed level important for the calculation of reach scale sediment volumes copyright 2000 john wiley sons ltd

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

lunar meteorites siderophile element contents and implications for the composition and origin of the moon abstract six lunar meteorites have thus far been discovered in antarctica although these meteorites are of undocumented lunar geographic provenance all other available lunar samples obtained from the apollo and luna programs came from a relatively minuscule region of the central nearside around which a polygon could be drawn covering just 4 7 of the lunar surface the five lunar meteorites that are now well studied represent at least two but probably three separate lunar source craters alha81005 and y791197 are probably from separate craters and compound meteorite y82192 6032 is certainly from a crater of its own at least alha81005 and y791197 and probably also at least in a loose sense y82192 6032 are highlands regolith breccias thus their compositions may be appropriately compared with compositions of apollo and luna highlands regolith samples compared with average highlands regolith samples from the central nearside apollo sites lunar meteorites have lower concentrations of siderophile elements in general and especially au ge and ni among anorthositic apollo samples i e mainly those from apollo 16 au ir and to a lesser extent ge ir ratios tend to be hyperchondritic most previous models for lunar regolith siderophile geochemistry assumed that the apollo 16 samples are representative of the overall lunar highlands such models tended to conclude that the hyperchondritic au ir and ge ir ratios were consequences of variations in the compositions of moon striking projectiles as a function of time it was even speculated that these temporal variations were consequences of the heterogeneous accretion of a moon with a general enrichment in refractory elements the lunar meteorites suggest that hyperchondritic au ir and ge ir are not general features of the highlands but peculiarities of the apollo 16 region or more generally the central nearside the high ni contents of the apollo 16 megaregolith substantially in excess of the ni implied by a model in which all meteoritic debris has an h chondritic ni ir ratio have been interpreted to imply that the mg rich fraction of the lunar crust is extremely ni rich and thus similar in siderophile geochemistry to terrestrial komatiites this coincidence has been interpreted as confirmation that the moon formed by modified fission from the earth s mantle after core formation plus late accretion effects had established the final siderophile pattern of the earth s mantle however the lunar meteorites and a survey of data for the luna 20 highlands regolith sample suggest that the high ni content of the apollo 16 regolith is strictly a peculiarity of the apollo 16 region and not a general feature of the moon s crust the anomalous siderophile composition of the central nearside regolith probably stems from a combination of regional heterogeneity in cratering projectile compositions plus regional enrichments in relatively labile siderophile elements most notably au ge and perhaps to a certain extent ni which might be loosely correlated with the anomalously high concentration of kreep over the central nearside

steady state behaviour of the black ven mudslide the application of archival analytical photogrammetry to studies of landform change the concept of dynamic equilibrium has provided geomorphologists with a challenging paradigm for studying landform evolution but quantitative evidence for its existence has proved illusive particularly for complex geomorphological systems the authors believe that the principle has now been verified through the application of the archival photogrammetric technique to a sequence of historical photographs spanning 50 years of process at the black ven mudslide complex in dorset u k the principles and limitations of the archival photogrammetric technique are described the method is applied to oblique and vertical aerial photographs of black ven at five epochs commencing in 1946 continuing at approximately 10 year intervals until 1988 the technique is used to generate plans contours sections and a dense and accurate digital elevation model dem of the whole site at each epoch this is used to generate dems of difference and a distribution of slope angle which suggest that the mudslides are in equilibrium despite the removal of 200 000 m3 of sediment between 1958 and 1988 extrapolation of the slope distribution through time suggests that the frequency of an episodic landform change model at black ven may be approximately 60 years

linking spatial patterns of bed surface texture bed mobility and channel hydraulics in a mountain stream to potential spawning substrate for small resident trout abstract in this paper we examined spatial patterns of bed texture bed mobility and channel hydraulics in four reaches of a mountain stream with moderate gradient

reaction and relaxation in a coarse grained fluvial system following catchment wide disturbance abstract the waiapu river catchment drainage area of 1734 km2 is one of the most prolific conveyors of sediment in the world annually delivering roughly 35 mt of fine material to the ocean from eroding gullies hillslopes and reworked sediment on valley floors tectonic and geologic influences in combination with a dynamic climate influenced by tropical cyclones and clearance of vegetation from steep hillslopes predisposes this region to high rates of erosion the bedload sediment regime of the river is strongly influenced by several exceptionally large gullies and gully complexes that produce a coarse grained poorly sorted sediment mixture rapid abrasion and breakdown leads to high rates of suspended sediment yield a wave of bedload material manifesting as elevated bed levels and significant widening of active alluvial fills has been triggered by large inputs of hillslope material from a few key tributary catchments following cyclone bola in 1988 we review the evidence for the relaxation process of the sedimentary system in the subsequent 29 years appraising some of the legacy effects that may endure as associated with reworking of the considerable alluvial stores within the waiapu system we use structure from motion sfm techniques and archival aerial photos to quantify changes in sediment storage at the base of two major gully systems in recent decades a record of over 850 cross section surveys at 62 sites on 10 rivers throughout the catchment 1958 2017 indicates recent transition from a trend of continuous accumulation to downcutting and remobilisation of valley bottom deposits the channel cross sections provide a minimum estimate of sediment flux from source areas to the lower reaches of the river giving a rudimentary but spatially extensive picture of the wave of material cascading through the drainage network the largest impacts occur in the upper steepland rivers closest to the landslide derived sediment supply transport rates here as inferred from cross section change are at a maximum during an aggradational phase following cyclone bola then taper off despite the large sediment accumulations remaining in the system as of 2017 the river is in the process of incising the upper extents of this deposit on a trajectory of recovery toward pre bola conditions the compilation of cross section data provides us with new insights into the sensitivity of particular sites in the landscape as well as the changing relationship between reach sediment storage and transport rates during the response and relaxation phase of a major disturbance in a large catchment

geomorphic impact and system recovery following an extreme flood in an upland stream thinhope burn northern england uk abstract quantitative assessments of the impacts of extreme floods on channel morphology are rare real time kinematic rtk gps surveys of a 500 m reach of the thinhope burn an upland gravel bed stream in the uk taken in 2003 and 2004 permitted an assessment of geomorphic work whilst the channel was at steady state a large flood that occurred on 17 july 2007 resulted in a catastrophic impact to the thinhope burn valley floor the reach was re surveyed after the event in 2007 and again in 2008 and in 2011 digital elevation models were produced from the survey data which allowed the spatial patterns of erosion and deposition and volumetric changes between surveys to be established a total of 5202 m3 of deposition and 2125 m3 of erosion was recorded in the reach following the flood event field walking of the catchment and comparison of aerial photographs for 2003 and 2007 suggested that most of the material mobilised had originated from existing sediment held in terraces and paleoberms on the valley floor although slope failures were evident including peat slides in the headwaters delivery of sediment from coupling zones to the channel was thought to play a secondary role in the geomorphic response shown by the channel similarly large volumes of erosion and deposition were found after resurveys in 2008 and 2011 suggesting that the system was still in its relaxation phase the results obtained in this investigation coupled with historical information on the flood history of thinhope burn dating back to 1766 suggested that rare large floods are the geomorphically effective flows in the catchment

some things we can infer about the moon from the composition of the apollo 16 regolith randy l korotev department of earth and planetary sciences and mcdonnell center for the space sciences washington university st louis missouri 63130 usa author s e mail address rlk levee wustl edu received 1996 september 16 accepted in revised form 1997 may 12 abstract characteristics of the regolith of cayley plains as sampled at the apollo 16 lunar landing site arereviewed and new compositional data are presented for samples of 1 mm fines soils and 1 2 mm rego lith particles as a means of determining which of the many primary igneous and secondary crystalline brec cias lithoiogic components that have been identified in the soil are volumetrically important and providing anestimate of their relative abundances more than 3 x 106 combinations of components representing nearly everylithology that has been observed in the apollo 16 regolith were systematically tested to determine which com binations best account for the composition of the soils conclusions drawn from the modeling include the fol lowing at the site mature soil from the cayley plains consists of 64 5 2 7 components representing prebasin materials anorthosites feldspathic breccias and a small amount 2 6 1 5 of total soil ofnonmare mafic plutonic rocks mostly gabbronorites on average these components are highly feldspathic with average concentrations of 31 32 a1203 and 2 3 feo and a molar mg mg fe ratio of 0 68 theremaining 36 of the regolith is syn and postbasin material 28 8 2 4 mafic impact melt breccias mimbs i e lkfm and vha basalts created at the time of basin formation 6 0 1 4 mare derived material impact and volcanic glass crystalline basalt with an average tio2 concentration of 2 4 and 1 postbasin meteoritic material the mimbs are the principal 80 90 carrier of incompatible traceelements rare earths th etc and the carrier of about one half of the siderophile elements and elementsassociated with mafic mineral phases fe mg mn cr sc most 71 of the fe in the present regolithderives from syn and postbasin sources mimbs mare derived material and meteorites thus althoughthe bulk composition of the apollo 16 regolith is nominally that of noritic anorthosite the noritic part themimbs and the anorthositic part the prebasin components are largely unrelated there is compositionalevidence that 3 4 of the soil is th rich material such as that occurring at the apollo 14 site and one frag ment of this type was found among the small regolith particles studied here if regolith such as that repre sented by the apollo 16 ancient regolith breccias was a protolith of the present regolith such regolith cannotexceed 71 of the present regolith the rest must be material added or redistributed since closure of theancient regolith breccias the postclosure material includes the mare derived material and the apollo 14 like component compositions of all mature surface soils from apollo 16 even those collected 4 km apart on the cayleyplains are very similar which is in stark contrast to the wide compositional range of the lithologies of whichthe soil is composed this uniformity indicates that the ratio of mimbs to feldspathic prebasin componentsis not highly variable in the megaregolith over distances of a few kilometers that there are no large sub surface concentrations of pure mafic impact melt breccia and that the intimate mixing is inherent to thecayley plains at a gross scale thus the mixing ofmafic impact melt breccias and feldspathic prebasin com ponents must have occurred during formation and deposition of the cayley plains such uniformity could nothave been achieved by small postdeposition impacts into a stratified megaregolith using this conclusion asone constraint and the known distribution of th on the lunar surface as another and the assumption that the im brium impact is primarily responsible for formation of the cayley plains arguments are presented that theapollo 16 mimbs derive from the imbrium region and consequently that one fourth of the apollo 16 regolithis primary imbrium ejecta in the form of mafic impact melt breccias

monitoring and modelling morphological change in a braided gravel bed river using high resolution gps based survey recent research in fluvial geomorphology has emphasized the direct monitoring of channel topography as a useful tool to better understand the interrelationship between river form and process and in particular to estimate bedload transport rates and reach scale sediment budgets until recently however this morphometric approach has been limited to comparison of repeatedly surveyed cross sections with the associated problems of low frequency sampling and an emphasis on cross stream as opposed to downstream morphological dynamics recent advances in analytical photogrammetry have however permitted the acquisition of data at sufficient resolutions to represent macroform 101 m and microform 10 m channel geometry in fully three dimensions while inherently spatially distributed the photogrammetric approach to land surveying is however restricted to observable areas of the channel and is thus of limited use in the subaqueous zone especially if flows are turbid or highly coloured this paper presents an alternative approach to the study of three dimensional morphological dynamics of a divided reach of the gravelly river feshie scotland in which topographic survey of both exposed and submerged areas of the reach was undertaken using the global positioning system gps survey results from two field programmes in 1998 and 1999 are presented in which a geotronics geotracer 2000 real time kinematic gps receiving unit was used to survey a 200 80 m reach rapid radial survey methods were employed permitting the collection of 2000 survey points per day giving a mean density over the 13 ha reach of 1 1 points per square metre a detailed assessment of survey errors and dem quality is presented and a limit of detection of c 10 cm proposed as an upper threshold for the identification of significant change between dems preliminary interpretation of channel dynamics in 1998 99 reveals relatively little change to the overall macroscale reach structure dem differencing techniques however highlight important local changes including the progradation of submerged bar fronts bar head aggradation and scour along major channel thalwegs and the erosion of fines from sloughs copyright 2000 john wiley sons ltd

composition structure and age of the apollo 16 subregolith basement as deduced from the chemistry of post imbrium melt bombs irregularly shaped slag like impact melt bombs with variolitic crystallization texture mostly 1 to 10 cm in size occur throughout the regolith of the apollo 16 landing site we have analyzed 16 samples from stations 11 and 13 near north ray crater using the microscope electron microscope microprobe neutron activation and 40ar 39ar age dating techniques we interpret the melt rocks as rapidly quenched high velocity ejecta glass bombs from impact craters less than 1 5 km in diameter located in the vicinity of the apollo 16 landing site a comparison between glass bombs and typical regolith samples from various sampling stations reveals differences in their bulk chemical compositions more than 80 of the glass bombs cannot be derived from the melting of the regolith but can be produced by melting the subregolith basement the differences in chemical composition of metal particles in glass bombs and regolith samples are consistent with these findings mixing calculations show that the glass bombs were formed by melting of two or more of the most abundant lithologies granulites feldspathic melt breccias anorthosites and various mafic melt breccias of vha and lkfm affinity that constitute the subregolith basement from these results we conclude that the subregolith basement represents a polymict megabreccia target the glass bombs are post cayley in age they were produced by several different impact events more than 370 ma ago by which they were emplaced in proximity to the north ray crater area they were buried under a younger regolith layer until the north ray impact event 50 ma ago brought them up to the lunar surface again and since then they have been exposed to cosmic radiation

morphodynamic signatures of braiding mechanisms as expressed through change in sediment storage in a gravel bed river previous flume based research on braided channels has revealed four classic mechanisms that produce braiding central bar development chute cutoff lobe dissection and transverse bar conversion the importance of these braiding mechanisms relative to other morphodynamic mechanisms in shaping braided rivers has not yet been investigated in the field here we exploit repeat topographic surveys of the braided river feshie uk to explore the morphodynamic signatures of different mechanisms of change in sediment storage our results indicate that when combined the four classic braiding mechanisms do indeed account for the majority of volumetric change in storage in the study reach 61 total chute cutoff traditionally thought of as an erosional braiding mechanism appears to be the most common braiding mechanism in the study river but was more the result of deposition during the construction of diagonal bars than it was the erosion of the chute three of the four classic mechanisms appeared to be largely net aggradational in nature whereas secondary mechanisms including bank erosion channel incision and bar sculpting were primarily net erosional although the role of readily erodible banks in facilitating braiding is often conceptualized we show that bank erosion is as or more important a mechanism in changes in sediment storage than most of the braiding mechanisms and is the most important secondary mechanism 17 of total change the results of this study provide one of the first field tests of the relative importance of braiding mechanisms observed in flume settings

close range digital photogrammetric analysis of experimental drainage basin evolution brasington james smart r m a 2003 close range digital photogrammetric analysis of experimental drainage basin evolution earth surface processes and landforms 28 3 pp 231 247 rae2008 special issue the generation of high quality topographic data for hydrology and geomorphology

mapping and quantifying sediment transfer between the front of rapidly moving rock glaciers and torrential gullies abstract the sedimentary connection which may occur between the front of active rock glaciers and torrential channels is not well understood despite its potential impact on the torrential activity characterizing the concerned catchments in this study dems of difference dods covering various time intervals between 2013 and 2016 were obtained from lidar derived multitemporal dems for three rapidly moving rock glaciers located in the western swiss alps the dods were used to map and quantify sediment transfer activity between the front of these rock glaciers and the corresponding underlying torrential gullies sediment transfer rates ranging between 1500 m3 y and 7800 m3 y have been calculated depending on the sites sediment eroded from the fronts generally accumulated in the upper sectors of the torrential gullies where they were occasionally mobilized within small to medium sized debris flow events a clear relation between the motion rates of the rock glaciers and the sediment transfer rates calculated at their fronts could be highlighted along with the size of the frontal areas rock glacier creep rates influence thus directly sediment availability in the headwaters of the studied torrents the frequency magnitude of debris flow events varied between sites and was mainly related to the concordance of local factors such as topography water availability sediment availability or sediment type

application of uav photogrammetry for the multi temporal estimation of surface extent and volumetric excavation in the sa pigada bianca open pit mine sardinia italy in open pit mines monitoring of topographic and volumetric changes through time is found to be of great importance to support excavation stages and to plan rehabilitation strategies in this work we describe a geomatic approach to assess changes in surface mine extent and to quantify excavated volume in the sa pigada open pit mine sardinia italy we performed two drone based photogrammetric surveys in 2013 and 2015 and by means of the structure from motion sfm technique we obtained related 3d dense point clouds and digital orthophotos images were georeferenced thanks to a series of ground control points surveyed with geodetic gps distances between the two clouds were estimated with the recent multiscale model to model cloud comparison m3c2 plug in included in the cloudcompare open source software starting from cloud to cloud distances we calculated the excavated volume of mineral resources between the two surveys results of the m3c2 comparison supported the analysis of the two orthophotos through which accurate limits of the 2013 and 2015 active mine areas rehabilitated area and temporary dumps were identified and drawn in a digital map results obtained in this study suggest that the applied geomatic techniques are suitable for performing accurate change detection analysis in open pit environments and represent a valid support for scientists and technicians allowing to monitor with high spatial and temporal resolutions this approach can be also considered a valid tool to reduce environmental impact from mining

composition and maturity of apollo 16 regolith core 60013 14 abstract samples from every half centimeter dissection interval of double drive tube 60013 14 sections 60013 and 60014 were analyzed by magnetic techniques for fe concentration and surface maturity parameter i s feo and by neutron activation for concentrations of 25 lithophile and siderophile elements core 60013 14 is one of three regolith cores taken in a triangular array 40 50 m apart on the cayley plains during apollo 16 mission to the moon the core can be divided into three zones based both on i s feo and composition unit a 0 44 cm depth is compositionally similar to other soils from the surface of the central region of the site and is mature throughout although maturity decreases with depth unit b 44 59 cm is submature and compositionally more feldspathic than unit a regions of lowest maturity in unit b are characterized by lower sm sc ratios than any soil obtained from the cayley plains as a result of some unidentified lithologic component with low surface maturity the component is probably some type of mafic anorthosite that does not occur in such high abundance in any of the other returned soils unit c 59 62 cm is more mature than unit b and compositionally equivalent to an 87 13 mixture of soil such as that from unit a and plagioclase such as found in ferroan anorthosite similar soils but containing greater abundances of anorthosite plagioclase are found at depth in the other two cores of the array these units of immature to submature soil enriched to varying degrees compared to the mature surface soil in ferroan anorthosite consisting of 99 plagioclase are the only compositionally distinct subsurface similarities among the three cores each of the cores contains other units that are compositionally dissimilar to any soil unit in the other two cores these compositionally distinct units probably derive from local subsurface blocks deposited by the event s that formed the cayley plains the ferroan anorthosite with 99 plagioclase however must represent some subsurface lithology that is significant on the scale of tens of meters the compositional uniformity of the surface soil 0 10 cm depth over distances of kilometers reflects the large scale uniformity of the plains deposits the fine structure reflects small scale nonuniformity and the inefficiency of the impact mixing process at depths as shallow as even one meter

applications of remote sensing for geohazard mapping in coastal and riverine environments this paper reviews various types of remote sensing that can be applied to mapping and monitoring riverine and coastal geohazards it focuses on flooding ground instability erosion and sedimentation mainly drawing on examples from the uk both airborne and space borne systems are examined with assessments of the merits limitations and relative costs of each system remote sensing offers a wide range of useful techniques for mapping coastal and riverine features particularly where there are access problems associated with sites prone to flooding or slope instability

rapid melting dynamics of an alpine glacier with repeated uav photogrammetry abstract glacial retreat is a major problem in the alps especially over the past 40 years unmanned aerial vehicles uavs can provide an unparalleled opportunity to track the spatiotemporal variations in rapidly changing glacial morphological features related to glacial dynamics the objective of this study is to evaluate the potential of commercial uav platforms to detect the evolution of the surface topography and morphology of an alpine glacier over a short time scale through the repeated acquisition of high resolution photogrammetric data two high resolution uav surveys were performed on the ablation region of the morteratsch glacier swiss alps in july and september 2016 first structure from motion sfm techniques were applied to create orthophotos and digital surface models dsms of the glacial surface from multi view uav acquisitions the geometric accuracy of dsms and orthophotos was checked using differential global navigation satellite system dgnss ground measurements and an accuracy of approximately 17 cm was achieved for both models high resolution orthophotos and dsms made it possible to provide a detailed characterization of rapidly changing glacial environments comparing the data from the first and the second campaigns the evolution of the lower part of the glacier in response to summer ablation was evaluated two distinct processes were revealed and accurately quantified an average lowering of the surface with a mean ice thinning of 4 m and an average horizontal displacement of 3 m due to flowing ice these data were validated through a comparison of different algorithms and approaches which clearly showed the consistency of the results the melt rate spatial patterns were then compared to the glacial brightness and roughness maps derived from the september uav acquisition the results showed that the dsm differences describing the glacial melt rates were inversely related to the glacial brightness in contrast a positive but weaker relationship existed between the dsm differences and glacial roughness this research demonstrates that uav photogrammetry allows the qualitative and quantitative appreciation of the complex evolution of retreating glaciers at a centimetre scale spatial resolution such performance allows the detection of seasonal changes in the surface topography which are related to summer ablation and span from the processes affecting the entire glacier to those that are more local

active width of gravel bed braided rivers previous analyses have identified the active width of braided rivers the bed area over which bed load flux and short term morphological change occurs as an important element of braiding dynamics and predictions of bed load flux here we compare theoretical predictions of active width in gravel bed braided rivers with observations from sunwapta river and from a generic physical model of gravel braided rivers to provide general observations of the variation in active width and to develop an understanding of the causes of variation bed topography was surveyed daily along a 150 m reach of the pro glacial sunwapta river for a total of four weeks during summer when flow was above threshold for morphological activity in the laboratory detailed digital elevation models dems were derived from photogrammetric survey at regular intervals during a constant discharge run from the field and flume observations there is considerable local and circumstantial variation in active width but also a general trend in average active width with increasing discharge there is also a clear relationship of active width with active braiding index number of active branches in the braided channel network and with dimensionless stream power which appears to be consistent across the range of data from field and physical models thus there is a link between active width and the river morphology and dynamics and the possibility of a general relationship for estimating active width from channel pattern properties or reach scale stream power values from which approximate bedload flux calculations may be made the analysis also raises questions about differences between hydraulically based numerical model computations of instantaneous active width and observation of time integrated morphological active width understanding these differences can give insight into the nature of bedload transport in braided rivers and the relationship to morphological processes of braiding copyright 2011 john wiley sons ltd

methodological sensitivity of morphometric estimates of coarse fluvial sediment transport abstract the estimation of fluvial sediment transport rate from measurements of morphological change has received growing recent interest the revival of the morphological method reflects continuing concern over traditional methods of rate determination but also the availability of new survey methods capable of high precision high resolution topographic monitoring remote sensing of river channels through aerial digital photogrammetry is a potentially attractive alternative to labour intensive ground surveys however while photogrammetry presents the opportunity to acquire survey data over large areas data precision and accuracy particularly in the vertical dimension are lower than in traditional ground survey methods this paper presents results of recent research in which digital elevation models dems have been developed for a reach of a large braided gravel bed river in scotland using both digital photogrammetry and high resolution rtk gps ground surveys a statistical level of change detection is assessed by comparing surfaces with independent check points the methodological sensitivity of the annual channel sediment budget 1999 2000 to the threshold is presented results suggest that while the remote survey methods employed here can be used to develop qualitatively convincing moderate precision dems of channel topography rmse 0 21 m the remaining errors imply significant limits on reliable change detection which lead to important information losses tests at a 95 confidence interval for change detection show that over 60 of channel deposition and 40 of erosion may be obscured by the lower level of precision associated with photogrammetric monitoring when compared to ground survey measurements this bias reflects the difficulty of detecting the topographic signature of widespread but shallow deposition on bar tops

mixing levels the apennine front soil component and compositional trends in the apollo 15 soils variations in concentrations of lithophile elements in samples of apollo 15 soil can be explained in terms of only four chemical components three components are represented by extrusive rock types found at the apollo 15 site mare basalt kreep basalt and the pyroclastic green glass associated with breccia 15426 the fourth component the highlands component can be represented by soil from the apennine front particularly the soil obtained from the 55 57 cm depth interval of station 2 core 15007 8 among samples of apennine front soil this one appears to be the least contaminated by mare materials and may be our most typical sample of the apennine front highlands although soil fron the apennine front is itself a complex mixture of many types of highlands rocks it behaves as a single component with respect to mixing with the other three rock type components the various subcomponents of the apennine front soil e g melt rock and anorthositic norite that have been used in some mixing models are not required as discrete components in order to explain the compositional variation among samples of apollo 15 soil most of this compositional variation results from mare highlands mixing i e apennine front soil with mare basalt kreep basalt which probably derives from local possibly unexposed sources is also a variable component of the soil and is most prevalent in the soil from stations lm 6 and 9

the interaction between hydrology and geomorphology in a landscape simulator experiment an experimental landscape simulator has been developed which uses a rainfall simulator to create overland flow and erosion the simulator uses rainfall sprinklers that eliminate rainsplash and an artificial soil which has little cohesion experimental landscapes developed in the simulator evolved according to howard s headward growth model elements of glock s model could be identified during evolution i e initiation and maximum extension but other stages of this model were not observed i e extension and integration the horton concept of cross grading and micropiracy and stream piracy was not observed despite the dominance of overland flow nor the groundwater headward growth mechanism proposed by dunne the latter due to experimental design which eliminated any perched groundwater table the experimental apparatus produced model landscapes that are scaled down analogues of real world processes copyright 2001 john wiley sons ltd

experimental evidence of dynamic scaling and indications of self organized criticality in braided rivers the evolution of an experimental braided river produced in our laboratory has been monitored and analyzed it has been shown that in addition to the spatial scaling revealed by sapozhnikov and foufoula georgiou 1996a braided rivers also exhibit dynamic scaling this implies that a smaller part of a braided river evolves identically in the statistical sense to a larger one provided the time is renormalized by a factor depending only on the ratio of the spatial scales of those parts the small value of the estimated dynamic exponent z is interpreted as an indication that the evolution of small channels in a braided river system is to a large extent forced by the evolution of bigger channels the presence of dynamic scaling is further interpreted as indicating that braided rivers may be in a critical state and behave as self organized critical systems in a recent paper sapozhnikov and foufoula georgiou 1996a evidence was presented that natural braided rivers ex hibit anisotropic scaling self affinity in their geometrical structure within a range of scales spanning the width of the narrowest channel to the width of the braid plain in simple words within these scales if a small part of a braided river is stretched in a certain way along the mainstream direction and a certain different way along the perpendicular direction then this stretched part looks statistically the same as a bigger part of the river such anisotropically scaled objects are called self affine fractals and are characterized by two fractal exponents nx and ny the ratio nx ny characterizes the scaling anisotropy and the fractal dimension d 5 ny 2 nx 1 1 ny e g see sapozhnikov and foufoula georgiou 1995 indicates how densely the object fills the space in sapozhnikov and foufoula georgiou 1996a three natu ral braided rivers of different scales and different hydrological and sedimentological characteristics aichilik and hulahula in alaska and brahmaputra in bangladesh were analyzed for spatial scaling using the logarithmic correlation integral lci method developed by sapozhnikov and foufoula georgiou 1995 interestingly enough it was observed that despite their different scales 0 5 15 km in braid plain width slopes 7 3 10 23 8 310 25 and types of bed material gravel to sand all three rivers exhibited anisotropic spatial scaling with almost the same fractal exponents nx 5 0 72 0 74 and ny 5 0 51 0 52 the x axis being oriented along the river and the y axis being in the perpendicular direction in simple terms this im plies that if parts of a braided river are stretched by l along the mainstream direction and by l n y n x l 0 7 along the perpen dicular direction the resulting images will look statistically similar to each other similarity within a braided river at the same time the invariance of nx and ny between braided rivers of different sizes and hydrology sedimentology suggests that the same anisotropic scaling as above applied to different riv ers will result in statistically similar images apart possibly from a normalization factor to account for the different mass of each river note that mass here refers to the area i e number of pixels covered with water the presence of such a statistical scale invariance in the spatial structure of braided rivers apart from being interesting in its own right might indicate the presence of universal features in the underlying mechanisms responsible for the formation of braided rivers and deserves further theoretical and experimental investiga tion braided rivers besides their complex geometry at any in stant of time are also highly dynamic systems characterized by intensive erosion sediment transport and deposition and fre quent channel shifting as they evolve predicting the evolution of braided rivers in terms of frequency and magnitude of chan nel shifting is of paramount importance where hydraulic struc tures or land developments are planned or where field use must be made of maps and air photos it is of great practical and theoretical value therefore to study the evolution of braided rivers in addition to their spatial structure in view of the evidence for spatial static scaling in braided rivers the question is asked here as to whether they also show dynamic scaling the presence of dynamic scaling would imply that space and time can be appropriately rescaled such that the evolution of the spatial structure of parts of the river of dif ferent size would be statistically indistinguishable the pres ence of dynamic scaling would also provide a highly desirable integrated framework for studying simultaneously the spatial and temporal structure of braided rivers

advances in the continuous monitoring of erosion and deposition dynamics developments and applications of the new peep 3t system abstract in most episodic erosion and deposition systems knowledge of the timing of geomorphological change in relation to fluctuations in the driving forces is crucial to strong erosion process inference and model building validation and development a challenge for geomorphology however is that few studies have focused on geomorphological event structure timing magnitude frequency and duration of individual erosion and deposition events in relation to applied stresses because of the absence of key monitoring methodologies this paper therefore a presents full details of a new erosion and deposition measurement system peep 3t developed from the photo electronic erosion pin sensor in five key areas including the addition of nocturnal monitoring through the integration of the thermal consonance timing tct concept to produce a continuous sensing system b presents novel high resolution datasets from the redesigned peep 3t system for river bank system of the rivers nidd and wharfe northern england uk and c comments on their potential for wider application throughout geomorphology to address these key measurement challenges relative to manual methods of erosion and deposition quantification continuous peep 3t methodologies increase the temporal resolution of erosion deposition event detection by more than three orders of magnitude better than 1 second resolution if required and this facility can significantly enhance process inference results show that river banks are highly dynamic thermally and respond quickly to radiation inputs data on bank retreat timing fixed with peep 3t tct evidence confirmed that they were significantly delayed up to 55 h after flood peaks one event occurred 13 h after emergence from the flow this suggests that mass failure processes rather than fluid entrainment dominated the system it is also shown how by integrating turbidity instrumentation with tct ideas linkages between sediment supply and sediment flux can be forged at event timescales and a lack of sediment exhaustion was evident here five challenges for wider geomorphological process investigation are discussed this event based dynamics approach based on continuous monitoring methodologies appears to have considerable wider potential for stronger process inference and model testing and validation in many areas of geomorphology

the effects of survey frequency on estimates of scour and fill in a braided river model an erratum has been published for this article in earth surface processes and landforms 27 7 2002 795 estimates of scour and fill in rivers that are derived by differencing topographic surfaces are known to be negatively biased by local compensation of scour and fill between surveys but the magnitude of bias is not well known this study examines the effect of survey frequency on volumes of scour and fill over a period of active channel braiding in a small scale river model a 100 min high temporal resolution time series of digital elevation models is artificially coarsened by selectively removing models the resulting four overlapping time series have survey intervals of 10 min 20 min 50 min and 100 min cumulative scour and fill volumes for the 100 min period are compared between the four series it is concluded that the decay in measured volumes of scour and fill with increased survey interval can be described using inverse functions cumulative scour fill volumes are approximately 420 per cent greater over the study period for 10 min survey intervals than for a 100 min interval after the 100 min period of competent flow nearly 65 per cent of the channel area experienced significant compensation of scour and fill several compensation mechanisms were identified in association with braided channel kinetics including lateral channel migration the migration of bed forms and channel avulsion it is demonstrated that by negatively biasing scour fill and net estimates this error significantly affects morphological approaches to the estimation of bed load sediment transport copyright 2002 john wiley sons ltd

glacial conditioning of stream position and flooding in the braid plain of the exit glacier foreland alaska abstract flow spilling out of an active braid plain often signals the onset of channel migration or avulsion to previously occupied areas in a recently deglaciated environment distinguishing between shifts in active braid plain location considered reversible by fluvial processes at short timescales and more permanent glacier conditioned changes in stream position can be critical to understanding flood hazards between 2009 and 2014 increased spilling from the exit creek braid plain in kenai fjords national park alaska repeatedly overtopped the only access road to the popular exit glacier visitor facilities and trails to understand the likely cause of road flooding we consider recent processes and the interplay between glacier and fluvial system dynamics since the maximum advance of the little ice age around 1815 patterns of temperature and precipitation the variables that drive high streamflow via snowmelt glacier meltwater runoff and rainfall could not fully explain the timing of road floods comparison of high resolution topographic data between 2008 and 2012 showed a strong pattern of braid plain aggradation along 3 km of glacier foreland not unexpected at the base of mountainous glaciers and likely an impetus for channel migration historically a dynamic zone follows the retreating glacier in which channel positions shift rapidly in response to changes in the glacier margin and fresh morainal deposits this period of paraglacial adjustment lasts one to several decades at exit glacier subsequently as moraine breaches consolidate and lock the channel into position and as the stream regains the lower elevation valley center upper elevation surfaces are abandoned as terraces inaccessible by fluvial processes for timescales of decades to centuries where not constrained by these terraces and moraines the channel is free to migrate which in this aggradational setting generates an alluvial fan at the breach of the final prominent moraine the position of this fan is glacially conditioned but the process of migration of the braided channels across it is not this broad perspective on channel controls identifies incipient avulsion into the roadside forest as part of a long term fan building process independent from changes in streamflow or sediment load

contaminated sediment flux from eroding abandoned historical metal mines spatial and temporal variability in geomorphological drivers abstract abandoned historical metal mines represent significant long term sediment source locations contributing highly contaminated anthropogenic legacy sediments to river systems despite this our understanding of spatial and temporal variability in the rates and geomorphological drivers of specific contaminated sediment source locations across abandoned mines remains poorly constrained in this study sediment flux from two abandoned historical lead mines in the north pennines uk was monitored over an 18 month period using repeat terrestrial laser scanning enabling the spatial and temporal significance of several common geomorphological processes to be quantified for the first time a novel contaminated sediment budget approach is used to integrate topographical change data with a pxrf survey of surface sediment metal concentrations approximately 434 t 289 t a 1 of eroded sediment entered the stream from a source area of 0 023 km2 the majority of the erosion was driven by two dominant processes with gullying accounting for 60 and bank erosion contributing 30 redeposition of eroded material within the survey area was minimal 3 indicating very high levels of coupling between source locations and the stream network and the export of the vast majority of eroded sediments 97 from the mined area rates for all erosive processes were highly episodic and primarily driven by high magnitude low frequency storm events metal concentrations in surface sediments exhibited considerable spatial variability with notable hotspots around the former ore processing areas and on the tailings heaps however 84 of all sediments sampled were in excess of available soil guideline values for pb and 65 in excess of equivalent guideline values for zn indicating that abandoned mine sites still have the potential to be significant sources of contaminant metals and pose a risk to the wider environment in total an estimated 4 59 t of pb and 2 14 t of zn entered the stream network in a sediment associated form during the 18 month monitoring period although these overall contaminated sediment inputs are high they are restricted to particular geomorphological processes are spatially variable in terms of the magnitude of specific source locations and are delivered in fairly discrete events this provides invaluable information for the future management of other abandoned mines and targeted mitigation of their potential legacy effects

compositional variation in apollo 16 impact melt breccias and inferences for the geology and bombardment history of the central highlands of the moon abstract high precision data for the concentrations of a number of lithophile and siderophile elements were obtained on multiple subsamples from 109 impact melt rocks and breccias mostly crystalline from the apollo 16 site compositions of nearly all apollo 16 melt rocks fall on one of two trends of increasing sm concentration with increasing sc concentration the eastern trend lower sm sc mg fe and sm yb ratios consists of compositional groups 3 and 4 of previous classification schemes these melt rocks are feldspathic poor in incompatible and siderophile elements and appear to have provenance in the descartes formation to the east of the site the western trend higher sm sc mg fe and sm yb ratios consists of compositional groups 1 and 2 these relatively mafic kreep bearing breccias are a major component 35 of the cayley plains west of the site and are unusual compared to otherwise similar melt breccias from other sites in having high concentrations of fe ni metal 1 2 the metal is the carrier of the low ir au 0 3 chondritic siderophile element signature that is characteristic of the apollo 16 site four compositionally distinct groups 1m 1f 2db and 2nr of western trend melt breccias occur that are each represented by at least six samples compositional group 1 of previous classification schemes the poikilitic or lkfm melt breccias can be subdivided into two groups group 1m represented by six samples including 60315 is characterized by lower al2o3 concentrations higher mgo and alkali concentrations and higher mg fe and cr sc ratios than group 1f represented by fifteen samples including 65015 group 1m also has siderophile element concentrations averaging about twice those of group 1f and ir au and ir ni ratios that are even lower than those of other western trend melt rocks ir au 0 24 0 03 ci normalized at the mafic extreme of group 2 vha melt breccias the melt lithology occurring as clasts in feldspathic fragmental breccias from north ray crater group 2nr is compositionally distinct from the melt lithology of dimict breccias from the cayley plains group 2db in having higher concentrations of sc cr and heavy rare earth elements and lower concentrations of siderophile elements the distinct siderophile element signature high absolute abundances low ir au ratio suggest that the four groups of mafic melt breccia are all somehow related ratios of some lithophile elements also suggest that they are more closely related to each other than they are to melt breccias from other apollo sites however none of the breccia compositions can be related to any of the others by any simple process of igneous fractionation or mixing involving common lunar materials thus the origin of the four groups of mafic melt breccia is enigmatic if they were produced in only one or two impacts then a mechanism exists for generating regimes of impact melt breccia in a single impact that are substantially different from each other in composition for various reasons including the problem of delivering large volumes of four different types of melt to the apollo 16 site it is unlikely that any of these breccias were produced in basin forming impacts if they were produced in as many as four crater forming impacts then the unusual siderophile element signature is difficult to explain possible explanations are 1 1 the four groups of melt breccia all contain metal from a single earlier impact 2 2 they were each formed by related metal rich meteoroids or 3 3 some common postimpact process has resulted in metal of similar composition in each of four melt pools within a compositional group most intrasample and intersample variation in lithophile element concentrations is caused by differences among samples in the proportion of a component of normative anorthosite or noritic anorthosite in most cases this compositional variation probably reflects variation in clast abundance for group 2db and probably 2nr differences in abundance of a component of ferroan anorthosite estimated al2o3 32 accounts for the compositional variation for groups 1m and 1f the anorthositic component is more mafic estimated al2o3 26 some group 2 samples may be related by a troctolitic component of varying abundance

estimation of small scale soil erosion in laboratory experiments with structure from motion photogrammetry abstract the quantitative estimation of changes in terrain surfaces caused by water erosion can be carried out from precise descriptions of surfaces given by means of digital elevation models dems some stages of water erosion research efforts are conducted in the laboratory using rainfall simulators and soil boxes with areas less than 1 m 2 under these conditions erosive processes can lead to very small surface variations and high precision dems are needed to account for differences measured in millimetres in this paper we used a photogrammetric structure from motion sfm technique to build dems of a 0 5 m 2 soil box to monitor several simulated rainfall episodes in the laboratory the technique of dem of difference dod was then applied using gis tools to compute estimates of volumetric changes between each pair of rainfall episodes the aim was to classify the soil surface into three classes erosion areas deposition areas and unchanged or neutral areas and quantify the volume of soil that was eroded and deposited we used a thresholding criterion of changes based on the estimated error of the difference of dems which in turn was obtained from the root mean square error of the individual dems experimental tests showed that the choice of different threshold values in the dod can lead to volume differences as large as 60 when compared to the direct volumetric difference it turns out that the choice of that threshold was a key point in this method in parallel to photogrammetric work we collected sediments from each rain episode and obtained a series of corresponding measured sediment yields the comparison between computed and measured sediment yields was significantly correlated especially when considering the accumulated value of the five simulations the computed sediment yield was 13 greater than the measured sediment yield the procedure presented in this paper proved to be suitable for the determination of sediment yields in rainfall driven soil erosion experiments conducted in the laboratory

mineralogical and magnetic characterisation of iron titanium oxides in soils developed on two various basaltic rocks under temperate climate abstract the objective of this study was to characterize alteration processes of iron titanium oxides in andic soils developed on basaltic rocks under temperate climate among the magnetic minerals titanomagnetites are the most abundant and represent the major spinel in basalts in order to understand processes involved in the alteration of iron titanium oxides from basaltic rocks associated to soils two pedons developed on tertiary massive basaltic formations submitted to temperate climate were considered the magnetic minerals have been characterized by studying rock and soil magnetic parameters i e magnetic susceptibility and curie temperature chemical composition was investigated by optical and electron microscopy empa sem eds and by micro proton induced x ray emission pixe because mineralogy of the parent rocks controls those of the soils we have first studied the rocks the thermomagnetic curves obtained on the two studied rocks show that initial titanomagnetite is preserved in one sample mc rock while the other pc rock contains near pure magnetite possibly issued from exsolution process microscopic observations confirm the exsolution lamellae on titanomagnetites and show a cr content gradient in chromian spinel partially enclosed in olivine these observations suggest a deuteric alteration the two profiles exhibit increasing curie temperature between the rocks and soil horizons indicating a transformation of magnetic minerals results emphasize the maghemitization of iron titanium oxides in andic soils in a temperate climate

cobalt and nickel concentrations in the komatiite component of apollo 16 polymict samples reply to r l korotev abstract we agree with korotev that the abundances of siderophiles in apollo 16 breccias are anomalously large but do not accept his hypothesis that they were supplied by the impact of a hitherto unknown type of meteorite possessing a grossly non chondritic composition co ni and other siderophiles in apollo 16 breccias display systematic relationships which imply that a substantial proportion of these siderophiles were present as oxidised species in the lunar crust prior to the impacts of chondritic type meteorites with the lunar surface these pre existing indigenous lunar siderophiles were reduced to the metallic state to varying degrees during impact bombardment and became alloyed with chondritic meteoritic metal in this manner the metallic particles of complex and unusual compositions now present at the a16 site were formed the indigenous siderophiles present in the a16 crust prior to meteoritic bombardment may themselves have been derived from two distinct sources one endogenous and the other exogenous the first corresponds to basic and ultrabasic magmas formed by partial melting of the moon s deep interior which were erupted and then and intimately mixed into the lunar crust the latter represents basic and ultrabasic material ejected from the earth s primitive crust by early meteorite bombardment which then fell upon the lunar surface the siderophiles present in each of these components display terrestrial like abundance patterns because they are both ultimately of terrestrial origin the anomalously high abundances of siderophiles at the a16 site may reflect an important contribution from ejected terrestrial material overall the siderophile abundance patterns present in lunar highland breccias represent mixtures of terrestrial and chondritic components

a channel evolution model for subtropical macrochannel systems a channel evolution model cem represents stages of channel development in response to specific types of disturbance in recent years classic incised disturbed cems have provided process based understanding of channel adjustment and formed the cornerstone for river restoration and rehabilitation while broadly applicable to alluvial systems in temperate and semi arid regions these models cannot be assumed to be universally applicable lockyer creek in south east queensland australia has notable macrochannel morphology and is subject to high hydrological variability typical of many subtropical climates the aim of this paper is to present a case study of channel adjustment and evolution in lower lockyer creek to determine if existing cems adequately describe processes of channel adjustment and the associated trajectories of change typical of river systems in subtropical settings lockyer creek has recently been subjected to a spate of flooding resulting in significant channel erosion this offers an ideal opportunity to investigate the nature and rate of channel adjustment processes and place them in context of longer term geomorphic adjustments in these systems specifically we address two questions firstly do the classic incised disturbed cems adequately represent the observed macrochannel adjustment secondly if current cems are inadequate what is the channel evolution model for these systems of which lower lockyer creek is an example results show that these are non incising systems where wet flow bank mass failures wbmfs are the dominant process of channel adjustment they occur within the channel bank top boundary resulting in no change to overall bank top width furthermore subsequent floods deposit sediment in the failure scars and failure headwalls generally do not retreat beyond channel bank top channel adjustment has not followed the evolutionary stages for incised disturbed channels and a new four stage macrochannel cem is outlined for these subtropical systems the proposed cem illustrates a cyclical pattern of erosion by channel bank wbmf followed by re aggradation through deposition and oblique processes contributing to bank rebuilding this cem provides sufficient information to determine the stage of macrochannel adjustment enabling decisions to be made over whether intervention is required or will be successful

a komatiite component in apollo 16 highland breccias implications for the nickel cobalt systematics and bulk composition of the moon the lunar crust at the apollo 16 landing site contains substantial amounts of a primitive component in which the ferromagnesian group of elements is concentrated the composition of this component can be retrieved via an analysis of mixing relationships displayed by lunar breccias it is found to be a komatiite which is compositionally similar to terrestrial komatiites both in major and minor elements the komatiite component of the lunar crust is believed to have formed by extensive degrees of melting of the lunar interior at depths greater than were involved in the formation of the lunar magma ocean which was parental to the crust after formation of the anorthositic crust it was invaded by extensive flows and intrusions of komatiite magma from these deeper source regions the komatiites became intimately mixed with the anorthosite by intensive meteoroid impacts about 4 5 b y ago thereby accounting for the observed mixing relationships displayed by the crust the compositional similarity between lunar and terrestrial komatiites strongly implies a corresponding similarity between the compositions of their source regions in the lunar interior and the earth s upper mantle the composition of the lunar interior can be modelled more specifically by combining the komatiite composition with its liquidus olivine composition as determined experimentally in proportions chosen so as to produce a cosmochemically acceptable range of mg si ratios for the bulk moon except for higher feo and lower na2o the range of compositions thereby obtained for the bulk moon is very similar to the composition of the earth s upper mantle the effects of meteoritic contamination on the abundances of cobalt and nickel in lunar highland breccias were subtracted on the assumption that the contaminating projectiles were chondritic the cobalt and nickel residuals thereby obtained were found to correlate strongly with the mg fe content of the breccias demonstrating that the co and ni are associated with the ferromagnesian component of the breccias and are genuinely indigenous to the moon the lunar highland co and ni residuals also display striking ni co versus ni correlations which follow a similar trend to those displayed by terrestrial basalts picrites and komatiites the lunar trends provide further decisive evidence of the indigenous nature of the co and ni residuals and suggest the operation of extensive fractionation controlled by olivine liquid equilibria in producing the primitive component of the lunar breccias indigenous nickel abundances at the apollo 14 15 and 17 sites are much lower than at the apollo 16 site although rocks from all sites follow the same ni co versus ni trends it is suggested that the primitive component at the apollo 14 15 and 17 sites was generally of basaltic composition in contrast to the komatiitic nature of the apollo 16 primitive component

the great lunar hot spot and the composition and origin of the apollo mafic lkfm impact melt breccias thorium rich mafic impact melt breccias from the apollo 14 17 missions that is those breccias identified with the composition known as lkfm are regarded largely as products of basin forming impacts that penetrated the feldspathic crust and sampled underlying mafic material and magma ocean residuum carrying the compositional signature of kreep potassium rare earth elements phosphorous despite considerable compositional variation among such breccias compositions of all of them correspond to mixtures of only four components 1 a norite with composition generally similar to that of apollo 15 basalt mean abundance 58 range 30 95 2 fo 90 dunite mean 13 range 1 27 3 feldspathic upper crust mean 29 range 4 50 and feni metal 0 1 1 7 petrographic evidence has shown that much of the feldspathic component but none of the kreep component is clastic this observation and the high proportion of kreep norite component in the breccias suggest that the melt zone of the impact or impacts forming the breccias contained little feldspathic material but consisted predominantly of material with the average composition of kreep norite the dunite component probably derives ultimately from the upper mantle these conclusions support the hypothesis that the breccias were not formed in typical feldspathic crust but instead by one or more impacts into what is designated here the great lunar hot spot that is the anomalous th rich terrane in the imbrium procellarum area identified by the apollo and lunar prospector gamma ray spectrometers the lkfm composition is a special product of the great lunar hot spot and is not the average composition of the lower crust in typical feldspathic highlands similarly mg suite and alkali suite plutonic rocks of the apollo collection are likely all differentiation products of the hot spot not of plutons that might occur in typical feldspathic crust

apollo 16 site geology and impact melts implications for the geologic history of the lunar highlands the geology of the apollo 16 site is reconsidered on the basis of data from photogeology geochemical remote sensing and lunar samples the site possesses an upper surface of anorthositic gabbro and related rocks mafic components were deposited as basin ejecta the events involved in its geological evolution were the nectaris impact and the imbrium impact the role of large local craters in the history of the region was to serve as topographic depressions to accumulate basin ejecta the most abundant melt composition at apollo 16 is an aluminous variety of lkfm basalt supplied by the nectaris impact as ejected basin impact melt the mafic lkfm melt may have been supplied by the imbrium impact more aluminous melt groups are probably derived from local small craters the remainder of the deposits in the region are composed of anorthositic clastic debris derived from the nectaris basin the local crustal substrate and imbrium and other basins

capturing the spatiotemporal variability of bedload transport a time lapse imagery technique monitoring sediment transport in morphologically complex and labile channels remains a difficult task even at the laboratory scale to address this challenge a fully automated imagery technique for continuously mapping the spatial and temporal variability of bedload transport is proposed this method uses differentiated time lapse imagery taken from a fixed camera to detect bed variations induced by grain displacement the technique is not based on tracking the individual particles rather it evaluates macroscopic colour changes within a region that contains several grains which depend on the occurrence and intensity of the bedload transport image derived data were compared with the sediment flux measured during four flume experiments and produced good correspondence the method provides continuous tracking of the location of the transporting channels and enables estimation of local variations in the magnitude of the bedload flux moreover the spatial extent of the monitoring area offers an unprecedented opportunity to aggregate spatially dense and continuous data at the reach scale as needed to properly capture the full range of variability of morphologically complex and rapidly evolving gravel bed rivers despite being limited to laboratory scale physical experiments the method provides useful data to investigate fundamental morphodynamic processes such as bar migration bank erosion anabranches opening closure and the associate spatial and temporal scales further the data obtained have the potential to enhance numerical model calibration and improve our understanding of the complex dynamics of real world settings copyright 2017 john wiley sons ltd

petrology and geochemistry of lunar dimict breccia 61015 dimict breccia 61015 consists dominantly of granulated anorthosite and impact melt rock of vha very high alumina basalt composition the anorthosite is a typical apollo 16 ferroan anorthosite except that it is slightly more augite rich than most other ferroan anorthosites the breccia probably formed in the floor of an expanding crater cavity by the following process impact melt generated within the cavity was injected into underlying anorthositic bedrock and solidified rapidly and the anorthosite and melt rock were then fragmented by deformation in the later stages of the impact all the apollo 16 dimict breccias except perhaps 61016 appear to have formed in the same impact the source crater cannot yet be identified but it may be an intermediate sized 50 150 km diameter crater within a few hundred kilometers of the apollo 16 site in the direction of the imbrium basin of either pre nectarian or post nectarian pre imbrian age the breccia has been affected by at least one and perhaps as many as four recent small impacts the most recent was probably the south ray impact the recent impact s produced internal shock induced melting of the breccia and injected and coated the rock with externally derived impact melts the coating glass is heterogeneous its average composition is similar to the compositions of other apollo 16 coating glasses except that its tio2 content is lower the vein glass is unusually mafic and has very low tio2 for its al2o3 content the tio2 contents of these glasses establish that they cannot be melted soils their compositions require a mafic low tio2 protolith component that has not yet been identified among the large rock samples perhaps a very mafic member of the ferroan anorthosite suite

the importance of high resolution monitoring in erosion and deposition dynamics studies examples from estuarine and fluvial systems abstract erosion and deposition processes lie at the centre of geomorphological explanation but progress in understanding has been limited by a lack of appropriate high resolution monitoring methodologies which permit detection of erosion and deposition dynamics this paper presents a case for monitoring erosion and deposition at high temporal resolutions and uses hypothetical approaches supported by example erosion and deposition events and analyses drawn from estuarine and fluvial systems the paper first presents testable hypotheses to demonstrate the complexity of possible event combinations sequences and juxtapositions for the erosion driving forces which underpin the need for high resolution monitoring second it summarises recent improvements to the photo electronic erosion pin peep automatic erosion and deposition monitoring system including the novel concept of thermal consonance timing tct which is particularly promising because it helps to define the timing of nocturnal events and through the entire hydrograph third example results are discussed from high resolution monitoring of bank erosion at a tidal site at burringham on the river trent in northern england tidal banks are revealed to be much more dynamic than previous conventional monitoring has indicated a key result is that because the high resolution approach allows erosional and depositional activity to be assigned to specific periods of tidal inundation it becomes possible for the first time routinely to produce event based erosion 36 mm h 1 and deposition rates 4 5 and 8 4 mm h 1 such rate determinations are potentially very useful in the field validation of sedimentological and geomorphological models including grain settling and resuspension theory fourth through a longer term of aggregated daily data a striking 2 week cycle of deposition and erosion emerges which correlates most strongly with spring neap tidal cycling but is moderated by wind stress effects sediment was deposited on the bank relatively quickly over 4 5 days but then removed by erosion rather slowly over 9 10 days fifth the dangers of low resolution monitoring are illustrated by comparing the daily peep data set with a series resampled at a lower 14 day frequency to simulate the information generated by conventional resurvey methodologies the low frequency series failed adequately to represent the cyclicity mean range variability and trend of bank elevation changes and without this dynamics information rate and process definition is very difficult largely because of self concealing activity sixth a useful advance is illustrated by the fluvial erosion sequence for the river wharfe n england this shows how tct can generate rare and important results with the definition of the precise time of an erosion event within the hydrograph bank retreat here occurred very quickly after initial inundation and within 4 h of the flow peak information which can be used to define thresholds for entrainment e g critical shear stresses such high resolution monitoring helps to unravel some of the erosional effects of complex sequences combinations and juxtapositions of similar or different forcing events finally high resolution approaches have been adopted worldwide for fluvial estuarine mudflat and canal systems but considerable potential exists for their development and use in these and other contexts e g gully hillslope beach and dune environments to improve understanding and modelling of geomorphological processes more widely

assessment of sediment sources throughout the proglacial area of a small arctic catchment based on high resolution digital elevation models abstract the article presents calculations of quantitative modifications of the morphology of selected subsystems of a glacial valley through i identification of the spatial distribution of important sources of sediment ii assessment of the spatiotemporal variety of sediment volume and landform morphology and iii assessment of the role of particular subsystems in sediment distribution the study involved a comparison of the results of field measurements from 2010 to 2013 performed in the scott glacier catchment 10 1 km2 in nw wedel jarlsberg land spitsbergen the assessment of the landform surface changes was performed by means of a precise terrestrial laser scanning tls survey the applied field and post processing techniques for oblique laser scanning permitted the acquisition of digital elevation data at a resolution 0 01 m and density 500 pt m 2 this allowed the development of a detailed terrain model and balancing spatial quantitative changes in six research test areas 10 000 m2 located within two subsystems of the catchment in a cascade arrangement in the alluvial valley floor subsystem the survey covered 1 the glacier terminus 2 the intramarginal outwash plain 3 the extramarginal braid plain and 4 the alluvial fan and in the slope subsystem 5 the erosional depositional slope in the gorge through terminal moraines and 6 the solifluction slope three zones differing in terms of the spatiotemporal dynamics of geomorphic processes were distinguished within the two analysed valley subsystems in the valley floor subsystem these are i the zone of basic supply distribution throughout the melting season and ii the redeposition zone distribution particularly during floods and in the slope subsystem iii zone of periodical supply distributed mainly in periods of increased precipitation and rapid increases in temperature in summer and during snow avalanches in winter the glacier and the landforms of the channel and valley floor as well as slope sediments transported as a result of mass wasting processes and activity of the active permafrost layer constitute important sources of sediment supply over a short 3 year timescale evidence of major changes of the surface morphology slopes floodplain and channel platform resulted in varied sediment budgets the subtraction of consecutive dems of the test areas located in the alluvial valley subsystem revealed downstream spatial and volumetric differentiation from the predominance of erosion 79 of volume 43 of area to the dominance of deposition 90 91 respectively in upper part of the valley floor to erosion predominance in the central 88 95 and lower 87 82 part of valley floor the test areas located on the slope subsystem showed the opposite relationship deposition dominance 88 of volume 80 of area in the upper gorge and erosion dominance 99 99 respectively in the lower part solifluction slopes the analysis of short time repeated surveys 3 week survey where volumes were calculated following dem subtraction showed increased deposition 82 of volume 79 of area for the alluvial fan and for solifluction slopes 70 57 respectively

cobalt and nickel concentrations in the komatiite component of apollo 16 polymict samples abstract some estimates for the concentrations of co and ni in the primitive mafic component of apollo 16 breccias and soils are large comparable to concentrations in terrestrial komatiites these estimates may be erroneously high because the contribution from meteoritic contamination of the samples has been underestimated however even if the correction for meteoritic co and ni is valid and the calculated residual ni is not of meteoritic origin the ni is presently carried by fe ni metal while the fe and mg are carried by mafic silicates if any large scale separation of metal and silicate phases has occurred the concentration ratio of ni to fe mg in the mafic silicates of the ancient crust in the vicinity of the apollo 16 site has not been preserved by apollo 16 rocks apollo 16 polymict breccias and soils contain much higher concentrations of siderophile elements and fe ni metal than other nonmare samples from the moon thus it is likely that the ni mg fe ratio estimated for the komatiite component from apollo 16 samples is high compared to the actual ratio for the lunar crust

the nature of the meteoritic components of apollo 16 soil as inferred from correlations of iron cobalt iridium and gold with nickel concentrations of co ni ir and au in small samples of submature and mature soil from apollo 16 are highly variable correlations of fe co ir and au with ni indicate that the variation in siderophile element concentrations results from variation in the concentration of fe ni metal from these correlations the mean composition of the metal is inferred to be 5 6 ni and 0 36 co for a ni co ratio of 15 5 0 7 i e dissimilar to the chondritic ratio of 20 21 the fe ni metal is also characterized by low ir ni and ir au ratios compared to metal in ordinary chondrites metal with a similar composition is also found in metal rich noritic impact melt breccias that occur as discrete rocks as well as small clasts in ancient regolith breccias at apollo 16 mass balance models using lithophile element concentrations indicate that about 35 of the soil is noritic impact melt the fe ni metal associated with this component is sufficient to supply virtually all the ancient fe ni metal found in the typical apollo 16 soil 0 4 0 5 i e no other source is required the soil also contains 1 2 carbonaceous chondrite the concentration of this component appears to be relatively constant from sample to sample and does not contribute significantly to the variation in siderophile element abundances these two meteoritic components contribute nearly equal concentrations of ni to the typical apollo 16 soil

geomorphic change detection using historic maps and dem differencing the temporal dimension of geospatial analysis abstract the ability to develop spatially distributed models of topographic change is presenting new capabilities in geomorphic research high resolution maps of elevation change indicate locations processes and rates of geomorphic change and provide a means of calibrating temporal simulation models methods of geomorphic change detection gcd based on gridded models may be applied to a wide range of time periods by utilizing cartometric remote sensing or ground based topographic survey data to measure volumetric change advantages and limitations of historical dem reconstruction methods are reviewed with a focus on coupling them with subsequent dems to construct dems of difference dod which can be created by subtracting one elevation model from another to map erosion deposition and volumetric change the period of dod analysis can be extended to several decades if accurate historical dems can be generated by extracting topographic data from historical data and selecting areas where geomorphic change has been substantial the challenge is to recognize and minimize uncertainties in data that are particularly elusive with early topographic data this paper reviews potential sources of error in digitized topographic maps and dems although the paper is primarily a review of methods three brief examples are presented at the end to demonstrate gcd using dods constructed from data extending over periods ranging from 70 to 90 years

the impact of different gridding methods on catchment geomorphology and soil erosion over long timescales using a landscape evolution model many digital elevation models are gridded from irregularly spaced data this study examines differences in catchment geomorphology and hydrology as a result of kriging and delaunay triangulation gridding methods both methods have been widely used as tools for placing irregularly spaced data onto a regular grid in the past numerical modelling has been performed with little assessment of model input variability and the variability produced by different gridding methods has not been fully assessed given the importance of the impact of digital elevation model error and potential impact on model output little work has been done to understand the impact of this type of potential error examination of the different catchment realizations demonstrates that when using kriging point or block or delaunay triangulation there are subtle differences in catchment area and elevation as well as networking properties subtle differences also exist in hillslope profile nevertheless when comparing catchment descriptors such as the hypsometric curve area slope relationship and cumulative area distribution there is little hydrological and geomorphological difference between these catchments further when these digital elevation models are used as landscape input in a long term landscape evolution model i e siberia there is little geomorphological difference or hydrological difference between the two digital elevation models after a 50 000 year modelled period consequently either method is appropriate for the study catchment these findings provide confidence in the conversion of irregularly spaced data onto a regular grid using kriging or delaunay triangulation and that either method can be used copyright 2006 john wiley sons ltd

modeling river bed morphology roughness and surface sedimentology using high resolution terrestrial laser scanning 1 recent advances in technology have revolutionized the acquisition of topographic data offering new perspectives on the structure and morphology of the earth s surface these developments have had a profound impact on the practice of river science creating a step change in the dimensionality resolution and precision of fluvial terrain models the emergence of hyperscale survey methods including structure from motion photogrammetry and terrestrial laser scanning tls now presents the opportunity to acquire 3 d point cloud data that capture grain scale detail over reach scale extents translating these data into geomorphologically relevant products is however not straightforward unlike traditional survey methods tls acquires observations rapidly and automatically but unselectively this results in considerable noise associated with backscatter from vegetation and other artifacts moreover the large data volumes are difficult to visualize require very high capacity storage and are not incorporated readily into gis and simulation models in this paper we analyze the geomorphological integrity of multiscale terrain models rendered from a tls survey of the braided river feshie scotland these raster terrain models are generated using a new computationally efficient geospatial toolkit the topographic point cloud analysis toolkit topcat this performs an intelligent decimation of point cloud data into a set of 2 5 d terrain models that retain information on the high frequency subgrid topography as the moments of the locally detrended elevation distribution the results quantify the degree of terrain generalization inherent in conventional fluvial dems and illustrate how subgrid topographic statistics can be used to map the spatial pattern of particle size grain roughness and sedimentary facies at the reach scale

modeling the topography of shallow braided rivers using structure from motion photogrammetry abstract recent advances in computer vision and image analysis have led to the development of a novel fully automated photogrammetric method to generate dense 3d point cloud data this approach termed structure from motion or sfm requires only limited ground control and is ideally suited to imagery obtained from low cost non metric cameras acquired either at close range or using aerial platforms terrain models generated using sfm have begun to emerge recently and with a growing spectrum of software now available there is an urgent need to provide a robust quality assessment of the data products generated using standard field and computational workflows to address this demand we present a detailed error analysis of sub meter resolution terrain models of two contiguous reaches 1 6 and 1 7 km long of the braided ahuriri river new zealand generated using sfm a six stage methodology is described involving i hand held image acquisition from an aerial platform ii 3d point cloud extraction modeling using agisoft photoscan iii georeferencing on a redundant network of gps surveyed ground control points iv point cloud filtering to reduce computational demand as well as reduce vegetation noise v optical bathymetric modeling of inundated areas and vi data fusion and surface modeling to generate sub meter raster terrain models bootstrapped geo registration as well as extensive distributed gps and sonar based bathymetric check data were used to quantify the quality of the models generated after each processing step the results obtained provide the first quantified analysis of sfm applied to model the complex terrain of a braided river results indicate that geo registration errors of 0 04 m planar and 0 10 m elevation and vertical surface errors of 0 10 m in non vegetation areas can be achieved from a dataset of photographs taken at 600 m and 800 m above the ground level these encouraging results suggest that this low cost logistically simple method can deliver high quality terrain datasets competitive with those obtained with significantly more expensive laser scanning and suitable for geomorphic change detection and hydrodynamic modeling