planetary surface dating from crater size frequency distribution measurements partial resurfacing events and statistical age uncertainty abstract we describe the procedure to fit a cumulative production function polynomial to a partial crater size frequency distribution the technique is of particular use in deriving ages for surfaces which have undergone partial resurfacing events namely erosional or depositional events which have affected a limited diameter range of the crater population we demonstrate its use in obtaining times for both the surface formation and the resurfacing event we give a practical outline of the method for making age measurements from crater counts and how to identify resurfacing effects in the results we discuss the conversion of production function polynomials between common presentations and the statistical uncertainty of the determined ages with respect to the non linear chronology function and a minor refinement of data binning

estimates of primary ejecta and local material for the orientale basin implications for the formation and ballistic sedimentation of multi ring basins abstract a clear understanding of thickness distributions of primary ejecta and local material is critical to interpreting the process of ballistic sedimentation provenances of lunar samples the evolution of the lunar surface and the origin of multi ring basins the youngest lunar multi ring basin orientale provides the best preserved structure for determining the thicknesses of primary ejecta and local material in general the primary ejecta thickness was often estimated using crater morphometry however previous methods ignored either crater erosion the crater interior geometry or both in addition ejecta deposits were taken as mostly primary ejecta and as far as we know the local material thickness had not been determined for the orientale in this work we proposed a model based on matching measurements of partially filled pre orientale craters pfpocs with the simulations of crater erosion to determine their thicknesses we provided estimates of primary ejecta thickness distribution with the thickness of 0 85 km at cordillera ring and a decay power law exponent of b 2 8 the transient crater radius of 200 km excavation volume of 2 3 10 6 km 3 primary ejecta volume of 2 8 10 6 km 3 these results suggest that previous works e g fassett et al 2011 moore et al 1974 might overestimate the primary ejecta thicknesses of orientale and the primary ejecta thickness model of pike 1974a for multi ring basins may give better estimates than the widely cited model of mcgetchin et al 1973 and the scaling law for impacts into ottawa sand housen et al 1983 structural uplift decays slower than previously thought and rim relief is mostly rim uplift for orientale the main reason for rim uplift may be the fracturing and squeezing upward of the surrounding rocks the proportion of local material to ejecta deposits increases with increasing radial distance from basin center and the thickness of local material is larger than that of primary ejecta at distance larger than certain distance 1 5 basin radius for orientale these results suggest ballistic sedimentation is important for multi ring basins and ejecta deposits can t be considered as mostly primary ejecta everywhere

the mons rumker volcanic complex of the moon a candidate landing site for the chang e 5 mission mons rumker is a large volcanic complex in oceanus procellarum on the moon and is a candidate landing site for china s chang e 5 sample return mission we conducted a comprehensive study of the topography geomorphology composition and stratigraphy of the mons rumker region with multi source remote sensing data in order to better understand the geology of the region and provide further support for the chang e 5 mission the results show that the rumker plateau stands 200 1300 m above the surrounding mare surface and 75 of the plateau has a slope of less than 3 at a baseline length of 30 m domes are the most prominent volcanic landforms in mons rumker and a total of 22 domes were identified and divided into two types that may represent different stages of volcanic activity spectral analyses indicated that mons rumker is covered by low ti basalt and the dominant mafic mineral is high calcium pyroxene though signs of mixing of highland materials and basalt have been found mons rumker has three main basalt units and their absolute model ages are 3 71 ga 3 58 ga and 3 51 ga respectively steep sided domes could be the youngest volcanic features on the plateau with indications that they were active until the eratosthenian a new geologic map of the study region was produced and used to interpret and discuss the geologic evolution of the region finally we propose two candidate landing sites for the chang e 5 mission

modeling the provenance of the apollo 16 regolith 1 the regolith at the apollo 16 landing site the only apollo landing site in the central lunar highlands contains material derived from a number of sources a model that accounts for the introduction of basin ejecta and mixing of the megaregolith is used to estimate the abundance of basin material in the apollo 16 regolith megaregolith mixing model estimates of the abundance of primary ejecta from the imbrium serenitatis and nectaris basins are found to be present in roughly equal 8 10 proportions additionally the presence of mare derived material in the apollo 16 regolith suggests that a significant component of the regolith 15 23 is derived from lateral transport there are inherent difficulties in directly comparing model results with ground truth at apollo 16 results suggest shallower mixing during ejecta emplacement than predicted by oberbeck et al 1975

the nature of crater rays the copernicus example crater rays are formed during a cratering event as target material is ballistically ejected to distances of many crater radii forming narrow generally high albedo approximately linear features extending outward from the crater the nature of crater rays was examined for the lunar crater copernicus using new information on the composition of surface material from near ir reflectance measurements surface roughness from radar backscatter measurements and photogeologic data from available images part of the data analysis included use of mixing models to quantify the mixing systematics observed between primary ejecta and local substrate of the ray on the basis of compositional parameters from reflectance spectra primary material from copernicus can be detected in the surface material of rays in decreasing amounts with increasing radial distance e g 20 25 primary ejecta at six crater radii for distances greater than three crater radii the proportion of local material to primary ejecta observed from these compositional reflectance data is approximately equal to that predicted by previous laboratory and ballistic studies of craters within three crater radii the compositional data indicate a higher proportion of primary ejecta than predicted for extended areas along the ray that do not contain large secondary craters the primary ejecta is intimately mixed on the granular scale with local material throughout the regolith the relatively high albedo of the rays of copernicus is due to the feldspathic composition highland of the primary ejecta in rays emplaced on a mare substrate immature local substrate is only observed in copernicus s ray at large unmantied secondary craters or other areas with sufficient topographic slope to prevent the accumulation of mature soils crater rays are filamentous generally high albedo features that emanate nearly radially from young impact structures rays are narrow in relation to the crater radius extend distally for many crater radii and constitute a distinctive albedo feature around some of the largest and freshest lunar craters visible from earth synoptic views of ray systems figure la give the strong impression that the rays comprise bright material that has been excavated from the crater cavity and been emplaced beyond the continuous ejecta deposit if this visual impression is correct then the process that forms crater rays represents a significant mechanism for the lateral transport of primary material to great distances from its point of origin and particularly for craters larger than a let tens of kilometers in diameter constitutes a fundamental process for the regional mixing of crustal materials earth based telescopic images of the moon allowed the first studies and descriptions of rays and ray systems shoemaker 1962 described the arcuate and loop shaped streaks of the copernicus ray systems and showed that these patterns could be locally resolved into individual en echelon feather shaped elements 15 20 km in length with their long axes oriented approximately radially to the crater he noted the presence of elongate depressions or gouges in the ray system ranking in diameter from 8 km down to the limits of resolution and generally located at the proximal ends of the individual ray elements shoemaker observed that some of the gouges were

major lunar crustal terranes surface expressions and crust mantle origins in light of global remotely sensed data the igneous crust of the moon can no longer be viewed as a simple globally stratified cumulus structure composed of a flotation upper crust of anorthosite underlain by progressively more mafic rocks and a residual melt kreep sandwich horizon near the base of the lower crust instead global geochemical information derived from clementine multispectral data and lunar prospector gamma ray data reveals at least three distinct provinces whose geochemistry and petrologic history make them geologically unique 1 the procellarum kreep terrane pkt 2 the feldspathic high lands terrane fht and 3 the south pole aitken terrane spat the pkt is a mafic province coincident with the largely resurfaced area in the procellarum imbrium region whose petrogenesis relates to the early differentiation of the moon here some 40 of the th in the moon s crust is concentrated into a region that constitutes only about 10 of the crustal volume this concentration of th average 5 ppm and by implication the other heat producing elements u and k led to a fundamentally different thermal and igneous evolution within this region compared to other parts of the lunar crust lower crustal materials within the pkt likely interacted with underlying mantle materials to produce hybrid magmatism leading to the magnesian suite of lunar rocks and possibly kreep basalt although rare in the apollo sample collection widespread mare volcanic rocks having substantial th enrichment are indicated by the remote data and may reflect further interaction between enriched crustal residues and mantle sources the fht is characterized by a central anorthositic region that constitutes the remnant of an anorthositic craton resulting from early lunar differentiation basin impacts into this region do not excavate significantly more mafic material suggesting a thickness of tens of kilometers of anorthositic crust the feldspathic lunar meteorites may represent samples from the anorthositic central region of the fht ejecta from deep penetrating basin impacts outside of the central anorthositic region however indicate an increasingly mafic composition with depth the spat a mafic anomaly of great magnitude may include material of the upper mantle as well as lower crust thus it is designated a separate terrane whether the spa basin impact simply uncovered lower crust such as we infer for the fht remains to be determined

geo botanical evidence of late quaternary mass wasting in block field areas of virginia studies of block fields at massanutten mountain virginia document and provide information on the magnitude and frequency of mass movement on these coarse grained slopes block fields which traditionally have been considered relicts of pleistocene climate occur on and downslope from resistant massanutten sandstone in passage creek basin slopes are strewn with boulders and vegetative cover on the open block fields is absent to sparse several block fields were investigated for evidence of recent movement using the degree of lichen growth differences in block weathering and rock fall damaged trees temporal and spatial aspects of geomorphic processes can be inferred through dendrogeochronology corrasion scars and stem ages infer a minimum age for a geomorphic or hydrologic event high flows on passage creek coincided with tree ring determined dates of block field movement although pleistocene periglacial climate may have facilitated original formation of block fields some block fields now continue to spread downslope during intense runoff events present block field mass wasting may be the principal erosional process in these areas of resistant rock

steady as a rock biogeomorphic influence of nurse rocks and slope processes on kūpaoa dubautia menziesii shrubs in haleakalā crater maui hawai i abstract this study examines biogeomorphic interactions between nurse rocks slope processes and 300 k paoa dubautia menziesii shrubs in haleakal crater maui hawai i research objectives were to assess the association of k paoa with substrates upslope and downslope of plants and proximity to the closest rock uphill contrast shrub substrate relationships with site frequency of sediment types measure surface soil shear strength and compressibility on 50 paired locations near boulders and investigate the aggregation characteristics and spatial patterns of k paoa in relation to rock and substrate variation data analyzed came from three 100 plant surveys at 3 sites a plant census at 2720 2975 m altitude and wandering quarter transects wqts across two areas 2610 2710 m ground sediment cover was estimated along four phototransects on these sites data for the three 100 plant surveys included substrate type outcrops blocks cobbles pebbles exposed soil organic litter upslope from each plant and distance to the largest rock upslope the two surveys examined along wqts included substrate type found downslope from k paoa plant height plant diameters across and along the slope and distance between successively censused plants most plants grew downslope of nurse rocks 74 were adjacent to blocks or outcrops and 17 near cobbles plants showed avoidance for finer substrates only 5 3 and 2 7 grew on near bare soils and pebbles respectively about 92 of k paoa were 10 cm downslope of rocks 89 grew 2 cm away and 83 in direct contact with a rock some seedlings also grew on pukiawe leptecophylla tameiameiae nurse plants several stable rock microsites protected plants from disturbance by slope processes causing debris shift site sediments were significantly finer than substrates near plants shrubs grew preferentially adjacent to boulders 20 cm wide which were more common near plants than across sites soils downslope of 50 boulders mean 41 3 cm showed higher shear strength and compressibility than soils along rock sides these boulder dams stop descending debris steadily deflecting them toward rock sides whereas protected soils downslope of blocks are infrequently disturbed and develop into downslope elongated clast free fine earth flags k paoa were uniformly dispersed across slopes showing a single phase mosaic arrangement without apparent aggregation slopes where k paoa grows had a relatively uniform distribution of surface sediments observed k paoa patterns may have resulted from the array of microsites generated by surface rocks and sediments as shrubs simply responded to such spatial structure

retrieving root zone soil moisture profile from p band radar via hybrid global and local optimization we propose an inversion model for retrieving the root zone soil moisture profile using the p band radar observations and validate it using data collected during the airborne microwave observatory of subcanopy and subsurface airmoss mission the forward model utilized in this article uses an existing small perturbation method spm to calculate the electromagnetic wave scattered from multilayered rough surface dielectric structures to solve the inverse problem which is formulated as a least squares problem we utilize a novel global optimization technique that takes the advantage of the speed of a local optimization method while ensuring convergence to the global minimum we present the numerical results to demonstrate significant improvements in the inversion results and computational speed compared to the previously used airmoss baseline inversion algorithm the presented method is validated with in situ soil moisture measurements finally by utilizing a closed form analytical solution to richards equation we demonstrate improvements in the accuracy of our soil moisture retrieval results

geobotanical assessment in the great plains rocky mountains and himalaya abstract vegetation patterns and dendrochronology were used to study landforms and processes in three unique geographic areas specifically we report on geobotanical associations related to forest fires slope failures rivers and glaciers the work was conducted in the niobrara valley of the great plains of nebraska tensleep canyon of the bighorn mountains yellowstone teton fire areas of the snake river drainage in wyoming and the nanga parbat and batura areas of the western himalaya results indicate that geobotanical associations can be used to provide additional information to study landforms natural hazards and sediment yields in addition geobotany can be used to detect processes responsible for environmental change remote sensing technology can play an important role in detecting vegetation distributions and green biomass variations

the influence of glacier surface processes on the short term evolution of supraglacial tree vegetation the case study of the miage glacier italian alps supraglacial debris cover allows vegetation to colonize glacier surface and whenever it is enough stable and thick also shrubs and trees can germinate and grow supraglacial tree growth and distr

ballistic sedimentation of impact crater ejecta implications for the provenance of lunar samples and the resurfacing effect of ejecta on the lunar surface

soil organic carbon pools in the northern circumpolar permafrost region of all soils in the northern permafrost region is approximately 18 782 10 3 km 2 o r approximately 16 of the global soil area in the northern permafrost region organic soils peatlands and cryoturbated permafrost affected mineral soils have the highest mean soil organic carbon contents 32 2 69 6 kg m 2 here we report a new estimate of the carbon pools in soils of the northern permafrost region including deeper layers and pools not accounted for in previous analyses carbon pools were estimated to be 191 29 pg for the 0 30 cm depth 495 80 pg for the 0 100 cm depth and 1024 00 pg for the 0 300 cm depth our estimate for the first meter of soil alone is about double that reported for this region in previous analyses carbon pools in layers deeper than 300 cm were estimated to be 407 pg in yedoma deposits and 241 pg in deltaic deposits in total the northern permafrost region contains approximately 1672 pg of organic carbon of which approximately 1466 pg or 88 occurs in perennially frozen soils and deposits this 1672 pg of organic carbon would account for approximately 50 of the estimated global belowground organic carbon pool

distribution and effectiveness of nivation in mediterranean mountains penalara spain abstract snow accumulation is responsible for geomorphic and biogeographic processes taking place in the southern sector of the penalara massif in central spain 40 51 n 3 57 w max altitude 2428 m at pico de penalara this work compares the intensity of nivation on the eastern slope leeward of the prevailing westerly winds and heavily eroded by glacial activity during the pleistocene to that of the western slope on the windward side unaffected by glacial erosion and completely covered by a thick weathering mantle on the eastern slope nivation is effective only where the weathering mantle is exposed or on morainic formations it does not occur on the landforms derived from glacial erosion in contrast the western side shows almost no evidence of snow action except where catastrophic mass movements have altered the regularity of the slope during the post glacial epoch nivation cirques formed in the scars left by mass wasting in the last 30 years spring temperatures have increased and this activity has diminished the pattern of evolution observed at penalara can be extrapolated to other mediterranean mountains with similar characteristics such as marginal glacial activity during the pleistocene unconsolidated formations on the summits caused by chemical weathering and dry hot summers that can increase the effectiveness of nivation

on estimating contributions of basin ejecta to regolith deposits at lunar sites we have developed a quantitative model for predicting characteristics of ejecta deposits that result from basin sized cratering events this model is based on impact crater scaling equations housen schmitt and holsapple 1983 holsapple 1993 and the concept of ballistic sedimentation oberbeck 1975 and takes into account the size distribution of the individual fragments ejected from the primary crater using the model we can estimate for an area centered at the chosen location of interest the average distribution of thicknesses of basin ejecta deposits within the area and the fraction of primary ejecta contained within the deposits model estimates of ejecta deposit thicknesses are calibrated using those of the orientale basin moore hodges and scott 1974 and of the ries basin horz ostertag and rainey 1983 observed densities of secondary craters surrounding the imbrium and orientale basins are much lower than the modeled densities similarly crater counts for part of the northern half of the copernicus secondary cratering field are much lower than the model predicts and variation in crater densities with distance from copernicus is less than expected these results suggest that mutual obliteration erases essentially all secondary craters associated with the debris surge that arises from the impacting primary fragments during ballistic sedimentation if so a process other than ballistic sedimentation is needed to produce observable secondary craters regardless our ejecta deposit model can be useful for suggesting provenances of sampled lunar materials providing information complementary to photogeological and remote sensing interpretations and as a tool for planning rover traverses e g haskin et al 1995 2002

heterogeneous impact transport on the moon impact cratering is the dominant process for transporting material on the moon s surface an impact transports both proximal material continuous ejecta locally and distal ejecta crater rays to much larger distances quantifying the relative importance of locally derived material versus distal material requires understandings of lunar regolith evolution and the mixing of materials across the lunar surface the moon has distinctive albedo units of darker mare basalt and brighter highland materials and the contacts between these units are ideal settings to examine this question information on the amount of material transported across these contacts comes from both the sample collection and remote sensing data though earlier interpretations of these observations are contradictory the relatively narrow 4 5 km wide mixing zone at mare highland contacts had been interpreted as consistent with most material having been locally derived from underneath mare plains however even far from these contacts where the mare is thick highland material is abundant in some soil samples 20 requiring transport of highland material over great distances any model of impact transport on the moon needs to be consistent with both the observed width of mare highland contacts and the commonality of nonmare material in mare soil samples far from any contact in this study using a three dimensional regolith transport model we match these constraints and demonstrate that both local and distal material transports are important at the lunar surface furthermore the nature of the distal material transport mechanism in discrete crater rays can result in substantial heterogeneity of surface materials

little ice age mapping as a tool for identifying hazard in the paraglacial environment the case study of trentino eastern italian alps abstract the little ice age lia is a well recognized climatic event during which the glaciers in the alps advanced and reached their maximum holocene extent during their retreat following the lia the glaciers left large areas of loose or poorly consolidated glacial deposits in their forelands which are subject to paraglacial reworking and may represent potential hazards for human infrastructures in this study we present a regional scale mapping of the lia and post lia glacial deposits and a reconstruction of the maximum lia extents of glaciers in the same area this work is motivated by a local law requiring the classification of areas subject to natural hazards in trentino italian alps results highlight that glaciers shrunk by 63 from the lia maximum leaving 30 km 2 of unconsolidated deposits which are subject to geomorphic paraglacial processes potentially hazardous consequences can occur in particular during high magnitude instantaneous events causing debris and mud flows mass wasting from debris covered ice and floods from small moraine dammed lakes

a new method for measuring deformation on volcanoes and other natural terrains using insar persistent scatterers 1 we present here a new insar persistent scatterer ps method for analyzing episodic crustal deformation in non urban environments with application to volcanic settings our method for identifying ps pixels in a series of interferograms is based primarily on phase characteristics and finds low amplitude pixels with phase stability that are not identified by the existing amplitude based algorithm our method also uses the spatial correlation of the phases rather than a well defined phase history so that we can observe temporally variable processes e g volcanic deformation the algorithm involves removing the residual topographic component of flattened interferogram phase for each ps then unwrapping the ps phases both spatially and temporally our method finds scatterers with stable phase characteristics independent of amplitudes associated with man made objects and is applicable to areas where conventional insar fails due to complete decorrelation of the majority of scatterers yet a few stable scatterers are present

crater ejecta scaling laws fundamental forms based on dimensional analysis a model of crater ejecta is constructed using dimensional analysis and a recently developed theory of energy and momentum coupling in cratering events general relations are derived that provide a rationale for scaling laboratory measurements of ejecta to larger events specific expressions are presented for ejection velocities and ejecta blanket profiles in two limiting regimes of crater formation the so called gravity and strength regimes in the gravity regime ejecta velocities at geometrically similar launch points within craters vary as the square root of the product of crater radius and gravity this relation implies geometric similarity of ejecta blankets that is the thickness of an ejecta blanket as a function of distance from the crater center is the same for all sizes of craters if the thickness and range are expressed in terms of crater radii in the strength regime ejecta velocities are independent of crater size consequently ejecta blankets are not geometrically similar in this regime for points away from the crater rim the expressions for ejecta velocities and thickness take the form of power laws the exponents in these power laws are functions of an exponent that appears in crater radius scaling relations thus experimental studies of the dependence of crater radius on impact conditions determine scaling relations for ejecta predicted ejection velocities and ejecta blanket profiles based on measured values of are compared to existing measurements of velocities and debris profiles

estimating 1992 2000 average active layer thickness on the alaskan north slope from remotely sensed surface subsidence 1 the measurement of temporal changes in active layer thickness alt is crucial to monitoring permafrost degradation in the arctic we develop a retrieval algorithm to estimate long term average alt using thaw season surface subsidence derived from spaceborne interferometric synthetic aperture radar insar measurements our algorithm uses a model of vertical distribution of water content within the active layer accounting for soil texture organic matter and moisture we determine the 1992 2000 average alt for an 80 100 km study area of continuous permafrost on the north slope of alaska near prudhoe bay we obtain an alt of 30 50 cm over moist tundra areas and a larger alt of 50 80 cm over wet tundra areas our estimated alt values match in situ measurements at circumpolar active layer monitoring calm sites within uncertainties our results demonstrate that insar can provide alt estimates over large areas at high spatial resolution

exploring debris flow history and process dynamics using an integrative approach on a dolomitic cone in western austria the evolution of a debris flow cone depends on a multitude of factors in the hydrogeomorphic system investigations of debris flow history and cone dynamics in highly active catchments therefore require an integrative approach with a temporal and spatial resolution appropriate for the goals of the study we present the use of an orthophoto time series to augment standard dendrogeomorphic techniques to describe the spatio temporal dynamics of debris flows on a highly active cone in the western austrian alps analysis of seven orthophotos since 1951 revealed a migration of active deposition areas with a resulting severe loss of forest cover 80 and a mean tree loss per year of 10 4 range 1 3 16 6 trees per year analysis of 193 pinus mugo ssp uncinata trees allowed the identification of 161 growth disturbances corresponding to 16 debris flows since 1839 and an average decadal frequency of 0 9 events as a result of the severe loss of forest cover we speculate that 20 of the more recent events were actually captured in the tree ring record giving a decadal return interval of 7 5 events for a period of 60 years based on three annual field observations it is evident that this catchment the barenrufe produces very frequent 1 yr small in the order of a few 10 to 100 m3 debris flows with minor material relocation the specific challenges of tree ring analysis in this tree species and in highly active environments are explicitly addressed in the discussion and underline the necessity of employing complementary methods of analysis in an integrative manner copyright 2012 john wiley sons ltd

comparing the characteristics of rockfall talus and snow avalanche landforms in an alpine environment using a new methodological approach massif des ecrins french alps abstract the geometry and sedimentology of 49 talus slope deposits have been analysed in the french alps to show the effects of snow avalanche activity on their characteristics twenty slopes are heavily avalanche modified 15 are snow avalanche boulder tongues and 14 are rockfall talus slopes slope angle slope segmentation longitudinal and sorting indices provide criteria to differentiate these deposits although the transition from rockfall to avalanche dominated slopes is gradational a transitional talus is identified with distinctive characteristics

galileo observations of post imbrium lunar craters during the first earth moon flyby copernican age craters are among the most conspicuous features seen on the far side and western limb of the moon in the galileo multispectral images acquired in december 1990 among the new morphologic observations of far side craters are bright rays continuous ejecta deposits and dark rings associated with probable impact melt veneers these observations suggest that the mapped age assignments of several large far side craters ohm robertson and possibly lowell and lenz need revision new crater size frequency measurements on lunar orbiter images suggest the following age reassignments hausen 170 km diameter pythagoras 120 km and bullialdus 61 km from eratosthenian to upper imbrian and carpenter 60 km and harpalus 39 km from copernican to eratosthenian colors and albedos of craters away from impact melt veneers are correlated with their geologic emplacement ages as determined from counts of superposed craters these age color relations are used to estimate the emplacement age time since impact event for other copernican age craters these age color relations indicate a probable copernican age for 27 far side or western limb craters larger than 10 km diameter that were not previously mapped as copernican the apparent deficiency of copernican craters on the far side compared with the near side in published geologic maps is not present in our data age color trends differ between mare and highland regions and between the interiors and continuous ejecta of the craters similar trends are established for color and albedo versus soil maturity indices for the returned lunar samples with distinct trends for mare and highland soils however the mare versus highland offsets are reversed in the two comparisons these relations can be explained by variations in regolith thicknesses and rates of mixing with relatively fresh crystalline ejecta therefore the soil maturity trends represent longer geologic time periods in regions with thinner regoliths such as the maria

field investigations of the interaction between debris flows and forest vegetation in two alpine fans abstract a key objective in debris flow hazard mitigation is the reduction of the potential depositional area in the fan from this point of view forested areas are able to provide a protective function hindering the flow motion and promoting the surge deposition despite extensive research on alpine forests and their protective functions relatively few studies in the literature have quantitatively focused on the relationship between debris flow depositional features and vegetation in light of the above our research investigates how vegetation characteristics in the fan area interact with debris flow deposition field investigations were carried out in two alpine fans where debris flow events occurred in the summer of 2012 by recording the characteristics of 1567 involved trees and the associated deposit thicknesses this paper provides a data set that contributes to the improvement of the knowledge of these interaction processes the integration of literature findings and the analysis of the collected dataset adds insights into the relationships between tree characteristics and the dynamics of debris flow during the runout path the main results prove the capacity of the forest of uniformly promoting flow energy dissipation presence of high species diversity in debris flow deposits when comparing disturbed and undisturbed forest stands tree mortality largely affecting small diameters

biogeomorphological influence of slope processes and sedimentology on vascular talus vegetation in the southern cascades california abstract the vascular vegetation of alpine talus slopes between 2035 and 3095 m altitude was studied at lassen volcanic national park california in the cascade range taluses show a diverse flora with 79 plant species growth forms include coniferous trees shrubs suffrutices herbs graminoids and ferns spatial patterns of plant distribution were studied along 40 point intercept transects plant cover was low 0 32 7 on all slopes spatially variable and showed no consistent trends sedimentological characteristics were determined by photosieving next to 1500 plants this census indicated preferential plant growth on blocks and cobbles with 43 2 and 23 3 of the plants growing on these stones respectively fewer specimens were rooted on pebbles 13 or on stone free gravel areas 20 5 growth forms displayed different substrate preferences 92 5 of the shrubs and 83 of the suffrutices colonized blocks or cobbles but only 57 2 of the herbs and 59 8 of the graminoids grew on large stones plants are associated with large clasts because 1 coarse talus is more stable than fine sediment areas which are more frequently disturbed by various geomorphic processes and 2 large stones help conserve substrate water beneath them while moisture quickly evaporates from fine debris root patterns were studied for 30 plant species 10 specimens for each species were excavated and inspected and several root growth ratios calculated all species exhibited pronounced root asymmetry as roots for most plants grew upslope from their shoot base for 23 species all specimens had 100 of their roots growing upslope for the other 7 species 92 2 99 3 of below ground biomass extended uphill this uneven root distribution is ascribed to continual substrate instability and resulting talus shift as cascading debris progressively buries roots and stems plants are gradually pushed and or stretched downhill various disturbance events affect root development slope erosion following rubble removal often exposes plant roots debris deposition can completely bury plants some may survive sedimentation producing new shoots that grow through accumulated debris shrubs may propagate by layering as adventitious roots develop along buried stems or produce new clones along their roots slope processes may damage and transport plant pieces downhill some species can sprout from severed displaced root or stem fragments vegetation interacts with several geomorphic processes including debris flows grain flows rockfall snow avalanches frost creep and runoff larger plants may alter local patterns of debris movement and deposition damming cascading debris on their upslope side and deflecting sediments laterally to plant margins where they form narrow elongated stone stripes

physical and biological features of an active rock glacier in the italian alps we report on the key physical features of an active rock glacier that influence the distribution of plants and arthropods we also perform a comparison with neighboring scree slope and alpine grassland to test whether the environmental features of the rock glacier drive the presence of specific species assemblages compared with scree slope and grassland the studied rock glacier provides particular physical features that determine the presence of unique species plant distribution is mainly driven by grain size arthropod distribution is linked to grain size with cold adapted species found on areas with coarse grained deep debris which also shows a distinctive temperature regime with very low values throughout the year on the basis of these findings we advance the hypothesis that rock glaciers provide specific ecological conditions creating potential refugia for cold demanding species during warm climatic periods

alpine debris covered glaciers as a habitat for plant life debris covered glaciers represent a significant increasing fraction of glaciers and can host plant life on their surface the goal of this work was to evaluate the suitability of supraglacial debris as a habitat for plant life and to discuss its ecological and biogeographic role the research was carried out on the miage glacier mont blanc massif western alps italy vegetation cover was sampled using a regular sampling grid recording plant species and number of individuals in 71 plots detailed glaciological parameters surface temperature debris thickness glacier surface velocity were recorded or derived from published data relationships between vegetation and environmental variables were assessed through generalized linear models principal components analysis and canonical correspondence analysis the glacier surface hosted a high biodiversity with 40 vascular plant species including trees and shrubs plant cover was arranged along an altitude glacier velocity gradient whilst debris thickn

glacier shrinkage and slope processes create habitat at high elevation and microrefugia across treeline for alpine plants during warm stages abstract the temperature rise at the global level and glacier shrinkage are deemed to induce new dynamics between biotic and abiotic factors especially in mountain regions in this work we aimed to assess a the area made available after glacier retreat since the little ice age lia for the colonization of alpine plants b the ability of 14 alpine and nival species typically growing on peaks and in deglaciated areas to migrate and survive at lower elevations in microrefugia across the treeline ecotone in the adamello presanella massif rhaetian alps we collected presence data on 14 alpine species within 3 3 or 5 5 m plots according to slope landforms and deposits the analysis of the elevation range of the investigated species across the treeline was performed using sentinel 2 satellite images to derive the actual position of the upper and lower treeline the differences in the species elevation ranges across slope landforms in relation to the treeline elevation and aspect were detected with linear mixed models results showed that glaciers contracted sharply by more than 50 between the lia and 2006 making large deglaciated areas available more than 57 km2 all the studied species were found at low altitudes across the treeline ecotone from about 500 to 1200 m below their typical habitat six species cardamine resedifolia cerastium uniflorum leucanthemopsis alpina luzula alpinopilosa oxyria digyna saxifraga oppositifolia significantly exceeded the upper treeline in correspondence of alpine composite channels p the retreat of the alpine glaciers coupled with the intensification of paraglacial processes may favor new habitat opportunities at high elevation and microrefugia at low altitudes for nival and alpine species the widespread presence of microrefugia for alpine plants downslope during warm periods suggests a low incidence of biodiversity loss in the alpine regions due to climate change

structural uplift and ejecta thickness of lunar mare craters new insights into the formation of complex crater rims we investigate the elevated crater rims of lunar craters the two main contributors to this elevation are a structural uplift of the preimpact bedrock and the emplacement of ejecta on top of the crater rim here we focus on five lunar complex mare craters with diameters ranging between 16 and 45 km bessel euler kepler harpalus and burg we performed 5281 measurements to calculate precise values for the structural rim uplift and the ejecta thickness at the elevated crater rim the average structural rim uplift for these five craters amounts to sru 70 6 1 8 whereas the ejecta thickness amounts to et 29 4 1 8 of the total crater rim elevation erosion is capable of modifying the ratio of ejecta thickness to structural rim uplift however to minimize the impact of erosion the five investigated craters are young pristine craters with mostly preserved ejecta blankets to quantify how strongly craters were enlarged by crater modification processes we reconstructed the dimensions of the transient crater the difference between the transient crater diameter and the final crater diameter can extend up to 11 km we propose reverse faulting and thrusting at the final crater rim to be one of the main contributing factors of forming the elevated crater rim

landform vegetation units for investigating the dynamics and geomorphologic evolution of alpine composite debris cones valle dell avio adamello group italy abstract cluster analysis of 245 vegetation plots along 17 transects on alpine composite debris cones in the italian alps allowed us to classify complex mosaics of landforms and plant communities a variety of active and past geomorphic processes mass wasting avalanche activity and running water were responsible for the construction of the debris cones by assessing plant community distribution in the context of the different landform units and geomorphic processes represented in detailed geomorphological maps a sequence of landform vegetation units was identified this approach contributes to the assessment of environmental hazards on the cones and may also be applied in other environmental contexts plant community distribution and development in valle dell avio reflects the frequency and intensity of the processes that built composite alpine debris cones creating environmental gradients and or generating new habitats therefore this patchy landscape allows the preservation of local biodiversity with typical plant communities adapted to particular niches

a generalized radar backscattering model based on wave theory for multilayer multispecies vegetation a generalized radar scattering model based on wave theory is described the model predicts polarimetric radar backscattering coefficients for structurally complex vegetation comprised of multiple species and layers compared to conventional two layer crown trunk models modeling of actual forests has been improved substantially allowing better understanding of microwave interaction with vegetation the model generalizes an existing single species discrete scatterer model and by including scattering and propagation effects through judiciously defined vegetation layers enables its application to an arbitrary number of species types the scatterers within each layer are modeled as finite cylinders or disks having arbitrary size density and orientation as in the predecessor model the distorted born approximation is used to represent the propagation through each layer while scattering from each is modeled as a linear superposition of scattering from its respective random collection of scatterers interactions of waves within and between each layer and direct scattering from the ground are accounted for validation of the model is presented based on its application to 23 wooded savanna sites located in queensland australia and comparison with advanced land observing satellite alos phased arrayed l band synthetic aperture radar palsar and national aeronautics and space administration nasa jet propulsion laboratory jpl airborne synthetic aperture radar airsar data results indicate good agreement between simulated and actual backscattering coefficients particularly at hh and vv polarizations more discrepancies are found at hv polarizations and can be explained by uncertainties in the knowledge of input parameters such as inaccuracies in the surface model surface roughness parameterization and soil moisture

thermomechanical stress strain numerical modelling of deglaciation since the last glacial maximum in the adamello group rhaetian alps italy abstract deglaciated areas in the valleys of the italian alps have recently exhibited a high potential for geomorphologic hazards from diffuse deep seated gravitational deformations dsgsds caused by rock mass creep processes that can evolve into rock falls and rock avalanches a multidisciplinary approach that integrated geomorphologic surveys and stress strain numerical simulations was used to investigate the effects of the stress release that was induced by the last glacial maximum lgm in the adame valley italian alps no evidence of dsgsds has been found in this area however data are available to develop a well constrained evolutionary model of the valley deglaciation the extent and thickness of the southern extension of the adamello glacier the widest glacier in italy during its primary growth phases including those of the lgm three late glacial stages and the little ice age lia were reconstructed using glacial geological surveys and were reproduced using a finite difference stress strain sequential model spanning from the lgm to the present a thermomechanical numerical configuration was developed based on geomechanical field measurements that were collected from rock outcrops and data from laboratory tests specifically performed on intact rock samples the numerical simulations demonstrate that thermomechanical viscous behaviour cannot be neglected because the resulting strains on the slopes are significantly higher than those resulting from conventional elastoplastic behaviour the last major thermal effect in the rock masses reproduced using the model occurred from 11 5 ka until the lia the resulting displacement rates are as much as several tens of mm ka which are consistent with the absence of dsgsds in the adame valley as these rates are significantly lower than those previously obtained from dsgsds and other large landslides in the alps based on thermomechanical numerical solutions these rates should persist for the next 1000 years assuming that no variations in current climatic conditions occur

surviving the heavy bombardment ancient material at the surface of south pole aitken basin 1 the oldest deepest and largest basin recognized on the lunar surface is the south pole aitken spa basin in the time since its formation several processes have modified the original interior of the basin including the introduction of foreign material by impact basins during the period of heavy bombardment these later basins redistributed material ballistically across the lunar surface forming a mixed and crushed zone on the scale of about one kilometer deep models of crater excavation ejected material transport and mixing during emplacement are used to estimate the amount of foreign material from each basin event introduced into spa and the degree to which that material mixes with the surface of the interior of spa we varied the size of the transient craters for all basins the degree of mixing between foreign and local material and the number of basins considered in our evaluation our modeling results indicate that materials derived from the original spa melt breccia comprise at least 15 of the present regolith the most realistic combinations of model parameters predict a spa melt breccia component that ranges from 50 80 of the current surface regolith the compositional character of the spa interior has apparently not been obliterated by aeons of subsequent basin forming events

geology and scientific significance of the rumker region in northern oceanus procellarum china s chang e 5 landing region the rumker region 41 45 n 49 69 w is located in northern oceanus procellarum of the moon mons rumker is the most distinctive geological feature in the area the region is characterized by prolonged lunar volcanism late imbrian period to eratosthenian period forming multiple geologic units in the area including very low ti to low ti mare basalts high ti mare basalts and volcanic complexes each geologic unit has distinct element composition and mineral assemblages the rumker region overlying the procellarum kreep terrain was selected as the landing region for china s chang e 5 lunar sample return mission prelanding analyses of the geologic context and scientific potential are reported in this contribution we conducted detailed geological mapping using image spectral and altimetry data fourteen geological units were defined a geologic map was constructed and the geologic history was outlined the western mare units im1 im2 and im3 are imbrian aged 3 4 3 5 ga representing the major stage of lunar mare eruptive volcanism the eastern young mare units em3 and em4 2 ga are among the youngest mare basalts on the moon they have never been explored in situ or studied in the laboratory we suggest that samples returned from the eastern mare unit em4 could answer many fundamental questions and that this unit should be listed as the top priority landing site for chang e 5 sample return mission

lgm and late glacial fluctuations in the eastern alps abstract studies of glacier development in the eastern alps around the last glacial maximum lgm for more than a hundred years have created a reasonably well based knowledge of glacier extent sedimentation and palaeoclimate as well as chronology this was obtained from broad and detailed mapping palynological investigations and radiocarbon dating despite a very cold climate between 31 and 21 ka bp topographical constraints meant that glacier extent was limited to tributary valleys of the main trenches until about 24 ka bp then rapid ice build up in the main longitudinal valleys led to extended ice streams and to piedmont glaciers in the foreland this build up virtually ended at ca 21 ka bp according to radiocarbon dates obtained from organic matter embedded in the outwash and periglacial gravels niederterrasse the lgm possibly lasted 3000 4000 years and shows a short maximalstand and a more prolonged hochstand both connected with outwash deposits the ice decay was apparently very fast and the glaciers vanished from the longitudinal valleys probably within some hundreds of years this retreat was interrupted by two short oscillations of active glaciers in contact with huge masses of inactive ice occupying the main valley floors before these became totally ice free these events at the beginning of the oldest dryas ca 16 ka bp were followed by a distinct glacier readvance gschnitz marked by end moraines and outwash fans according to some radiocarbon dates this occurred around 14 ka bp during the bolling interstade the valleys became almost ice free the next two glacier readvances daun and egesen were limited to cirques and the higher parts of the valleys and are dated to the older and younger dryas stades respectively

the origin of lunar crater rays abstract lunar rays are filamentous high albedo deposits occurring radial or subradial to impact craters the nature and origin of lunar rays have long been the subjects of major controversies we have determined the origin of selected lunar ray segments utilizing earth based spectral and radar data as well as feo tio 2 and optical maturity maps produced from clementine uvvis images these include rays associated with tycho olbers a lichtenberg and the messier crater complex it was found that lunar rays are bright because of compositional contrast with the surrounding terrain the presence of immature material or some combination of the two mature compositional rays such as those exhibited by lichtenberg crater are due entirely to the contrast in albedo between ray material containing highlands rich primary ejecta and the adjacent dark mare surfaces immaturity rays are bright due to the presence of fresh high albedo material this fresh debris was produced by one or more of the following 1 the emplacement of immature primary ejecta 2 the deposition of immature local material from secondary craters 3 the action of debris surges downrange of secondary clusters and 4 the presence of immature interior walls of secondary impact craters both composition and state of maturity play a role in producing a third combination class of lunar rays the working distinction between the eratosthenian and copernican systems is that copernican craters still have visible rays whereas eratosthenian aged craters do not compositional rays can persist far longer than 1 1 ga the currently accepted age of the copernican eratosthenian boundary hence the mere presence of rays is not a reliable indication of crater age the optical maturity parameter should be used to define the copernican eratosthenian boundary the time required for an immature surface to reach the optical maturity index saturation point could be defined as the copernican period

subsurface structures of large volcanic complexes on the nearside of the moon a view from grail gravity abstract the lunar nearside large volcanic complexes such as the rumker hills aristarchus plateau and marius hills are likely sites of intense and sustained magmatic activity these volcanic complexes recently proposed to be shield volcanoes are generally located at regionally high elevations and some feature relatively well localized positive gravity anomalies applying localized spectral analyses on high resolution gravity data obtained from the gravity recovery and interior laboratory grail mission and topography data returned from the lunar reconnaissance orbiter lro spacecraft we study the subsurface structures of these volcanic complexes the gravity signal is predicted using a thin elastic lithospheric model that considers both surface and subsurface loads best fit crustal and load densities show that the topographic highs of rumker hills marius hills gardner and kepler are mainly composed of material that has a density of more than 2850 kg m 3 which is consistent with that of emplaced igneous rocks both the aristarchus plateau and hortensius have relatively lower crustal and surface load densities with mean values around 2550 kg m 3 which are well consistent with the average bulk density of the lunar highland crust these results together with evidence of multiple volcanic edifices on the surface suggest that the shallow crusts of the rumker hills marius hills gardner and kepler are mainly composed of dense intrusive extrusive magmatic units and those of the aristarchus plateau and hortensius are mainly composed of low density materials with only small amounts of superimposed volcanic material to further constrain the subsurface structures beneath these volcanic complexes we analyze the bouguer gravity anomalies for these regions results show that dense materials that might be solidified intrusions exist beneath rumker hills marius hills gardner and prinz but no substantial dense materials have been detected beneath the aristarchus plateau hortensius kepler or cauchy the different subsurface structures among these large volcanic complexes suggest that the volcanism style at the lunar nearside is different from each other even for those formed at the same geological time

earth and moon impact flux increased at the end of the paleozoic the terrestrial impact crater record is commonly assumed to be biased with erosion thought to eliminate older craters even on stable terrains given that the same projectile population strikes earth and the moon terrestrial selection effects can be quantified by using a method to date lunar craters with diameters greater than 10 kilometers and younger than 1 billion years we found that the impact rate increased by a factor of 2 6 about 290 million years ago the terrestrial crater record shows similar results suggesting that the deficit of large terrestrial craters between 300 million and 650 million years ago relative to more recent times stems from a lower impact flux not preservation bias the almost complete absence of terrestrial craters older than 650 million years may indicate a massive global scale erosion event near that time

outcrops on lunar crater rims implications for rim construction mechanisms ejecta volumes and excavation depths the raised rims of impact craters consist of ejecta deposited onto structurally uplifted target rocks although it is commonly accepted that ejecta makes up 50 75 of the total rim height no previous measurements on well preserved naturally occurring impact craters exist relying on data from the lunar reconnaissance orbiter i report the first direct measurements of the rim forming constituents from 21 lunar craters ranging in diameter from 2 2 km to 45 km results show that the ejecta deposit accounts for no more than 20 of rim relief and structural uplift is the primary mechanism of rim development in both simple and complex craters thick quasi horizontal outcrops of coherent bedrock indicate that this uplift is the result of subsurface injection of debris or melt into the surrounding target rocks crater growth at least during the latest portion of the excavation stage therefore proceeds mainly through injection rather than ejection of material these results suggest that ejecta volumes and excavation depths may be factors of 3 to 4 less than previously considered

retrieval of permafrost active layer properties using time series p band radar observations we propose a method to estimate the active layer properties including soil dielectric profiles and active layer thickness alt in permafrost regions using time series p band polarimetric synthetic aperture radar sar observations the active layer and underlying permafrost are modeled as a three layer dielectric structure with the layer dielectric constants representing the soil moisture and freeze thaw state of the layer to resolve the ambiguity of the retrieved layer thicknesses an approach of finding the largest possible depths lpds is combined with time series observations where the alt is assumed time invariant between the maximum thaw and before the upward freezing front rises significantly from the permafrost table the lpd assisted time series retrieval algorithm is applied to the radar data acquired by the airborne microwave observatory of subcanopy and subsurface airmoss p band sar in august and october 2014 and 2015 over the alaska north slope the results show that the retrieved alt values are generally underestimated for the sites where the in situ alt is larger than the p band sensing depth with a retrieval bias ranging from 0 05 to 0 24 m as validated against the in situ alt collected at circumpolar active layer monitoring calm sites for the sites where the in situ alt is smaller than 0 55 m the retrieval errors are generally less than 0 1 m the retrieval results also show that the active layer properties are strongly influenced by the land cover types at the regional scale and not as much by the north south temperature gradient across a 180 km long transect along the deadhorse flight line

geological characteristics of von karman crater northwestern south pole aitken basin chang e 4 landing site region von karman crater diameter 186 km lying in the northwestern south pole aitken spa basin was formed in the pre nectarian the von karman crater floor was subsequently flooded with one or several generations of mare basalts during the imbrian period numerous subsequent impact craters in the surrounding region delivered ejecta to the floor together forming a rich sample of the spa basin and farside geologic history we studied in details the targeted landing region 45 0 46 0 s 176 4 178 8 e of the 2018 chinese lunar mission chang e 4 within the von karman crater the topography of the landing region is generally flat at a baseline of 60 m secondary craters and ejecta materials have covered most of the mare unit and can be traced back to at least four source craters finsen von karman l von karman l and antoniadi based on preferential spatial orientations and crosscutting relationships extensive sinuous ridges and troughs are identified spatially related to ba jie crater diameter 4 km reflectance spectral variations due to difference in both composition and physical properties are observed among the ejecta from various sized craters on the mare unit the composition trends were used together with crater scaling relationships and estimates of regolith thickness to reconstruct the subsurface stratigraphy the results reveal a complex geological history of the landing region and set the framework for the in situ measurements of the ce 4 mission which will provide unique insights into the compositions of farside mare basalt spa compositional zone including spa compositional anomaly and mg pyroxene annulus regolith evolution and the lunar space environment