gullies and landslides on the moon evidence for dry granular flows 1 high resolution images from chandrayaan 1 terrain mapping camera and lunar reconnaissance orbiter camera reveal landslides and gully formation on the interior wall of a 7 km diameter simple crater emplaced in schrodinger basin on the farside of the moon these features occur on the steep upper crater wall where the slope is 35 the gullies show a typical alcove channel fan morphology some gullies incise bedrock where impact related faults are present slope failure along the concentric faults also led to formation of landslides dark slope streaks are abundant at the bright gully regions especially near the fan and channel deposits spectral characteristics inferred from data obtained by hyperspectral imager and moon mineralogy mapper on board chandrayaan 1 show that the gullies and landslides are characterized by high optical immaturity and devoid of prominent spectral absorption features related to water or hydroxyl molecules suggesting youthful dry granular flows mass movements on the crater wall led to the formation of arcuate ridges and ponding of fine grained sediments on the crater floor runout flows from small impact craters on the slopes indicate that impact induced seismic shaking was responsible for the downslope mass movements crater size frequency distributions suggest a minimum age of 18 2 ma for the gullies and 2 ma for the landslides while age of the host crater ejecta was inferred to be about 175 ma the gullies and landslides also occur on the interior wall of other impact craters elsewhere on the moon and probably formed by similar processes

the unique geomorphology and physical properties of the vestalia terra plateau abstract we produced a geologic map of the av 9 numisia quadrangle of asteroid vesta using dawn spacecraft data to serve as a tool to understand the geologic relations of surface features in this region these features include the plateau vestalia terra a hill named brumalia tholus and an unusual dark ribbon material crossing the majority of the map area stratigraphic relations suggest that vestalia terra is one of the oldest features on vesta despite a model crater age date similar to that of much of the surface of the asteroid cornelia numisia and drusilla craters reveal bright and dark material in their walls and both cornelia and numisia have smooth and pitted terrains on their floors suggestive of the release of volatiles during or shortly after the impacts that formed these craters cornelia fabia and teia craters have extensive bright ejecta lobes while diogenitic material has been identified in association with the bright teia and fabia ejecta hydroxyl has been detected in the dark material within cornelia numisia and drusilla three large pit crater chains appear in the map area with an orientation similar to the equatorial troughs that cut the majority of vesta analysis of these features has led to several interpretations of the geological history of the region vestalia terra appears to be mechanically stronger than the rest of vesta brumalia tholus may be the surface representation of a dike fed laccolith the dark ribbon feature is proposed to represent a long runout ejecta flow from drusilla crater

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

climate teleconnections at monthly time scales in the ligurian sea inferred from satellite data abstract the existence and spatial distribution of possible teleconnections between the south pacific and north atlantic oceans and the ligurian sea north western mediterranean are investigated in the present paper teleconnections are searched by cross correlating monthly spatio temporal time series of 1 1 km resolution sea surface temperature sst and a 22 2 km resolution sea level anomaly sla measured from satellite from march 1993 to august 1999 with two indices characterising the south pacific and the north atlantic variability the southern oscillation so and the north atlantic oscillation nao indices respectively concerning the variability induced by the north atlantic ocean it is shown that it mostly influences the sla field in the ligurian sea specifically relevant anti correlations between sla and north atlantic variability have been found in all the ligurian sub basin as expected by geographical proximity the effects of north atlantic on the sla field in the ligurian sea are instantaneous at monthly time scales instead correlations between sst and nao index are found at time lag 1 month in the southern part of the basin highlighting the memory of the ocean related to their heat capacity significant anti correlations between so index and the sst field in the ligurian sea were obtained at time lag 4 months in the coastal areas of the sub basin results also indicate that the impact of teleconnections in the area studied is not geographically uniform

characterising three dimensional anisotropic spatial correlation of soil properties through in situ test results proper characterisations of soil properties and their variations are pivotal to the geotechnical design process although multiple in situ soil tests are routinely specified and performed in geotec

erosional modification and gully formation at meteor crater arizona insights into crater degradation processes on mars hydrogeological modification of meteor crater produced a spectacular set of gullies throughout the interior wall in response to rainwater precipitation snow melting and possible groundwater discharge the crater wall has an exceptionally well developed centripetal drainage pattern consisting of individual alcoves channels and fans some of the gullies originate from the rim crest and others from the middle crater wall where a lithologic transition occurs broad gullies occur along the crater corner radial faults deeply incised alcoves are well developed on the soft coconino sandstone exposed on the middle crater wall beneath overlying dolomite in general the gully locations are along crater wall radial fractures and faults which are favorable locales of erosion due to preferential rock breakup from faulting and groundwater flow discharge these structural discontinuities are also the locales where the surface runoff from rain precipitation and snow melting can preferentially flow causing erosion and crater degradation channels are well developed on the talus deposits and alluvial fans on the periphery of the crater floor caves exposed on the lower crater level point to percolation of surface runoff and selective discharge through fractures on the crater wall in addition lake sediments on the crater floor provide significant evidence of a past pluvial climate when the water table was higher and groundwater may have seeped from springs on the crater wall although these hydrological processes continue at meteor crater today conditions at the crater are much more arid than they were soon after impact reflecting a climatic shift this climate shift and the hydrological modifications observed at meteor crater provide insights for landscape sculpturing on mars during various parts of its history

the long lived and recent seismicity at the lunar orientale basin evidence from morphology and formation ages of boulder avalanches tectonics and seismic ground motion

how old are young lunar craters 1 the accurate definition of the lunar cratering chronology is important for deriving absolute model ages across the lunar surface and throughout the solar system images from the lunar reconnaissance orbiter narrow angle cameras and wide angle camera and the selene kaguya terrain camera provide new opportunities to investigate crater size frequency distributions csfds on individual geological units at lunar impact craters we report new csfd measurements for the copernican aged craters north ray tycho and copernicus which are crucial anchor points for the lunar cratering chronology we also discuss possible reasons for an age discrepancy observed between the impact melt and ejecta units our csfds for north ray and tycho crater ejecta deposits are consistent with earlier measurements however for copernicus crater and one of its rays we find significantly lower cumulative crater frequencies than previous studies our new results for copernicus crater fit the existing lunar absolute chronologies significantly better than the previous counts our derived model ages of the ejecta blankets of north ray tycho and copernicus agree well with radiometric and exposure ages of the apollo 16 17 and 12 landing sites respectively and are generally consistent with a constant impact rate over the last 3 ga however small variations of the impact rate cannot be resolved in our data and require further investigations

spectral and photogeologic mapping of schrodinger basin and implications for post south pole aitken impact deep subsurface stratigraphy abstract schrodinger basin provides a window into the stratigraphy of the lunar crust adjacent to the south pole aitken basin region that we have probed with lunar reconnaissance orbiter moon mineralogy mapper m 3 and crater scaling relationships the composition of materials that make up the basin wall impact melt and peak ring provide a cross section of the lunar crust which reveals products of the lunar magma ocean subsequent magmatism and reworking of those components into a megaregolith large hectometer to kilometer size areas of anorthite rich material anorthosite low ca pyroxene material a noritic unit and olivine rich material troctolite or dunite are exposed with a few areas of intermediate composition the schrodinger impact excavated 20 km into an orthopyroxene plagioclase noritic lunar crust which is exposed in the basin walls rim and proximal ejecta and dominates the composition of materials that make up the basin floor substantially later in lunar history two spatially and chronologically isolated volcanic eruptions occurred on the basin floor two large craters east of schrodinger excavated a compositionally gabbroic subsurface unit that was not tapped by schrodinger this indicates a compositional crustal facies change which may be from spa ejecta but could reflect heterogeneity in the original lunar crust

mediterranean thermohaline response to large scale winter atmospheric forcing in a high resolution ocean model simulation large scale circulation anomalies over the north atlantic and euro mediterranean regions described by dominant climate modes such as the north atlantic oscillation nao the east atlantic pattern ea the east atlantic western russian eawr and the mediterranean oscillation index moi significantly affect interannual to decadal climatic and hydroclimatic variability in the euro mediterranean region however whereas previous studies assessed the impact of such climate modes on air sea heat and freshwater fluxes in the mediterranean sea the propagation of these atmospheric forcing signals from the surface toward the interior and the abyss of the mediterranean sea remains unexplored here we use a high resolution ocean model simulation covering the 1979 2013 period to investigate spatial patterns and time scales of the mediterranean thermohaline response to winter forcing from nao ea eawr and moi we find that these modes significantly imprint on the thermohaline properties in key areas of the mediterranean sea through a variety of mechanisms typically density anomalies induced by all modes remain confined in the upper 600 m depth and remain significant for up to 18 24 months one of the clearest propagation signals refers to the ea in the adriatic and northern ionian seas there negative ea anomalies are associated to an extensive positive density response with anomalies that sink to the bottom of the south adriatic pit within a 2 year time other strong responses are the thermally driven responses to the ea in the gulf of lions and to the eawr in the aegean sea moi and eawr forcing of thermohaline properties in the eastern mediterranean sub basins seems to be determined by reinforcement processes linked to the persistency of these modes in multiannual anomalous states our study also suggests that nao ea eawr and moi could critically interfere with internal deep and abyssal ocean dynamics and variability in the mediterranean sea

seasonal variability of water transport through the straits of gibraltar sicily and corsica derived from a high resolution model of the mediterranean circulation abstract the variability of the water transport through three major straits of the mediterranean sea gibraltar sicily and corsica was investigated using a high resolution model this model of the mediterranean circulation was developed in the context of the mercator project the region of interest is the western mediterranean between the strait of gibraltar and the strait of sicily the major water masses and the winter convection in the gulf of lions were simulated the model reproduced the meso scale and large scale patterns of the circulation in very good agreement with recent observations the western and the eastern gyres of the alboran sea were observed but high interannual variability was noticed the algerian current splits into several branches at the longitude of the strait of sicily level forming the tyrrhenian branch and the atlantic ionian stream and the atlantic tunisian current in the eastern mediterranean the north current retroflexed north of the balearic islands and a dome structure was observed in the gulf of lions the cyclonic barotropic algerian gyre which was recently observed during the mater and elisa experiment was evidenced in the simulation from time series of 10 day mean transport the three straits presented a high variability at short time scales the transport was generally maximum in april for the strait of gibraltar in november for the strait of sicily and in january for the strait of corsica the amplitudes of the transport through the straits of gibraltar 0 11 sv and sicily 0 30 sv presented a weaker seasonal variability than that of the strait of corsica 0 70 sv the study of the relation between transport and wind forcing showed that the transport through the strait of gibraltar is dependent on local zonal wind over short time scales 70 which was not the case for the other straits less than 30 the maximum minimum of the transport occurred for an eastward westward wind stress in the strait an interannual event was noticed in november december 2001 which corresponded to a very low transport 0 3 sv which was characterised by a cyclonic circulation in the western alboran sea that circulation was also reproduced by the model for other periods than winter during the interannual simulation the transport through the strait of sicily is not influenced by local wind the wind stress curl of the northwestern mediterranean influenced the transport through the strait of corsica

a novel topographic parameterization scheme indicates that martian gullies display the signature of liquid water martian gullies resemble gullies carved by water on earth yet are thought to have formed in an extremely cold 50 c and dry humidity 100 precipitable micrometers surface environment cf mellon et al 2004 despite more than a decade of observations no consensus has emerged as to whether liquid water is required to form martian gullies with some recent studies favouring dry co2 driven processes that this argument persists demonstrates the limitations of morphological interpretations made from 2d images especially when similar looking landforms can form by very different processes to overcome this we have devised a parameterization scheme based on statistical discriminant analysis and hydrological terrain analysis of meter scale digital topography data which can distinguish between dry and wet surface processes acting on a landscape applying this approach to new meter scale topographic datasets of earth the moon and mars we demonstrate that martian gullied slopes are dissimilar to dry gullied slopes on earth and the moon but are similar to both terrestrial debris flows and fluvial gullies we conclude that liquid water was integral to the process by which martian gullies formed finally our work shows that quantitative 3d analyses of landscape have great potential as a tool in planetary science enabling remote assessment of processes acting on planetary surfaces

long term monitoring of martian gully formation and evolution with mro hirise abstract gully landforms are commonly taken as evidence for surface liquid water in the recent geological history of mars repeat observations with the high resolution imaging science experiment hirise instrument on the mars reconnaissance orbiter demonstrate widespread activity in gullies in the southern hemisphere particularly in those with the freshest morphologies this activity includes substantial channel incision and large scale mass movements and constitutes ongoing gully formation rather than degradation of older landforms new apron deposits that are bright dark and neutrally toned have all been observed the timing of gully activity is seasonally controlled and occurs during the period when seasonal frost is present and defrosting these observations support a model in which currently active gully formation is driven mainly by seasonal co 2 frost gullies in the northern hemisphere are far less active than those in the south this may be due to the current timing of perihelion near the northern winter solstice integrated over time activity like that observed within the past few years appears capable of forming all of the martian gully landforms on timescales of millions of years additionally the current style and rate of activity is able to erase meter to decameter scale surface features that might have been uniquely produced by other processes during the last obliquity high 0 4 ma although it is impossible to rule out a past role for water in the formation of martian gullies a model in which gullies form only through currently active processes with little or no liquid water is consistent with our observations

variations in sub tropical deep weathering profiles over the kowloon granite hong kong variations in the physical characteristics of the weathering profile over the kowloon granite in hong kong have been established using borehole records supported by field mapping there is a strong correlation between topography of the weathered profile base and the main structural trends linear zones of deep weathering have been preferentially eroded to create valleys which subsequently became sites of alluvial and colluvial accumulation variations in weathering patterns are primarily a function of the geometry and infilling of relict jointing which together determine local hydrogeology and hence intensity of weathering magnetic susceptibility is a reliable indicator of material weathering grade in the kowloon granite corestones are generally restricted to weathered profiles over topographically high areas the locations of which are controlled by regional joint spacing and orientation corestone bearing profiles are rare and more commonly deeply weathered granite without corestones passes abruptly into relatively fresh rock this has important implications for engineering ground models derived from borehole interpretation

inter annual variations of surface currents and transports in the sicily channel derived from coastal altimetry twenty year coastal altimetry data set x track is used for the first time to gain insight into the long term inter annual variations of the surface circulation in the sicily channel firstly a spectral along with a time space diagram analysis are applied to the monthly means of the x track geostrophic currents over the period 1993 2013 they reveal a regionally coherent current patterns from track to track with a marked inter annual variability that is unequally shared between the atlantic tunisian current and atlantic ionian stream inflows in the sicily channel and the bifurcation tyrrhenian current outflow northeast of sicily secondly an empirical altimetry based transport like technique is proposed to quantify volume budgets inside the closed boxes formed by the crossing of the altimetry tracks and coastlines over the study area a set of hydrographic measurements is used to validate the method the inferred altimetry transports give a well balanced mean eastward atlantic waters baroclinic flow of 0 4 sv and standard deviations of 0 2 sv on a yearly basis throughout the sicily channel and toward the ionian sea which is fairly coherent with those found in the literature furthermore the analysis allows to quantify the intrusions of atlantic waters over the tunisian shelf 0 12 0 1 sv and highlights two main modes of variability of the main surface waters path over the sicily channel through the bifurcation atlantic tunisian current and atlantic ionian stream systems some physical mechanisms are finally discussed with regards to changes in the observed currents and transports

testing the water hypothesis quantitative morphological analysis of terrestrial and martian mid latitude gullies abstract although martian gullies resemble terrestrial counterparts two conflicting hypotheses exist for their formation still invoke fluvial processes on the one hand or lubricated co 2 flows on the other in this work we compared the quantitative morphology of terrestrial gullies known to have formed by liquid water and mid latitude martian gullies in the martian southern hemisphere we also compared these results with measurements of martian dry ravines adjacent to the gullies our results show a similarity between martian and terrestrial gully formation supporting the hypothesis that liquid water was involved in their erosion our results show dry ravines differ morphologically from gullies further suggesting fluidised flows as a likely origin of the latter variations in the relationships across various terrestrial and martian gullies indicate the significance of local environmental and geological conditions our work supports the idea that martian gullies may not have been formed by just one single process but may have evolved through a more complex interaction of processes and environment

the pianosa contourite depositional system northern tyrrhenian sea drift morphology and plio quaternary stratigraphic evolution abstract the pianosa contourite depositional system cds is located in the corsica trough northern tyrrhenian sea a confined basin dominated by mass transport and contour currents in the eastern flank and by turbidity currents in the western flank the morphologic and stratigraphic characterisation of the pianosa cds is based on multibeam bathymetry seismic reflection data multi channel high resolution mini gi gun single channel sparker and chirp sediment cores and adcp data the pianosa cds is located at shallow to intermediate water depths 170 to 850 m water depth and is formed under the influence of the levantine intermediate water liw it is 120 km long has a maximum width of 10 km and is composed of different types of muddy sediment drifts plastered drift separated mounded drift sigmoid drift and multicrested drift the reduced tectonic activity in the corsica trough since the early pliocene permits to recover a sedimentary record of the contourite depositional system that is only influenced by climate fluctuations contourites started to develop in the middle late pliocene but their growth was enhanced since the middle pleistocene transition 0 7 0 9 ma although the general circulation of the liw flowing northwards in the corsica trough remained active all along the history of the system contourite drift formation changed controlled by sediment influx and bottom current velocity during periods of sea level fall fast bottom currents often eroded the drift crest in the middle and upper slope at that time the proximity of the coast to the shelf edge favoured the formation of bioclastic sand deposits winnowed by bottom currents higher sediment accumulation of mud in the drifts occurred during periods of fast bottom currents and high sediment availability i e high activity of turbidity currents coincident with periods of sea level low stands condensed sections were formed during sea level high stands when bottom currents were more sluggish and the turbidite system was disconnected resulting in a lower sediment influx

recent shallow moonquake and impact triggered boulder falls on the moon new insights from the schrodinger basin shallow moonquakes are thought to be of tectonic origin however the geologic structures responsible for these moonquakes are unknown here we report sites where moonquakes possibly occurred along young lobate scarps in the schrodinger basin our analysis of lunar reconnaissance orbiter and chandrayaan 1 images revealed four lobate scarps in different parts of the schrodinger basin the scarps crosscut small fresh impact craters 1500 boulders associated with trails and bouncing marks their origins are largely controlled by recent impact events ejecta rays and secondary crater chains from a 14 km diameter impact crater traversed schrodinger and triggered significant boulder falls about 17 ma therefore a combination of recent shallow moonquakes and impact events triggered the boulder falls in the schrodinger basin

ancient multiring basins on the moon revealed by clementine laser altimetry analysis of laser altimetry data from clementine has confirmed and extended our knowledge of nearly obliterated multiring basins on the moon these basins were formed during the early bombardment phase of lunar history have been filled to varying degrees by mare lavas and regional ejecta blankets and have been degraded by the superposition of large impact craters the mendel rydberg basin a degraded three ring feature over 600 kilometers in diameter on the lunar western limb is about 6 kilometers deep from rim to floor only slightly less deep than the nearby younger and much better preserved orientale basin 8 kilometers deep the south pole aitken basin the oldest discernible impact feature on the moon is revealed as a basin 2500 kilometers in diameter with an average depth of more than 13 kilometers rim crest to floor this feature is the largest deepest impact crater yet discovered in the solar system several additional depressions seen in the data may represent previously unmapped ancient impact basins

integrated framework for characterization of spatial variability of geological profiles despite recent efforts to characterize the uncertainties involved with geological profiles and soil and rock properties there has been limited study on their spatial correlations and how such features may be included in the engineering decision making process this paper presents an integrated framework for geostatisical analyses which incorporates the restricted maximum likelihood reml method with the matern autocovariance model statistical tests are conducted including those for data normality constant variance and outliers which ensure the fundamental assumptions of reml are not violated in the residual analyses of site data meanwhile offering simple checks for potential errors in the dataset the proposed approach also allows quantification of uncertainties in the subsurface profiles at the unsampled locations the approach is illustrated through investigations on spatial correlation features of geological profiles at two project sites in hong kong the number of irregularly spaced boreholes

new morphological mapping and interpretation of ejecta deposits from orientale basin on the moon abstract orientale basin is one of the youngest and best preserved multi ring impact basins in the solar system the structure is 950 km across and is located on the western edge of the nearside of the moon the interior of the basin which possesses three distinct rings and a post impact mare fill has been studied extensively using modern high resolution datasets exterior to these rings orientale has an extensive ejecta blanket that extends out radially for at least 800 km from the basin rim in all directions and covers portions of both the nearside and farside of the moon these deposits known as the hevelius formation were first mapped using photographic data from the lunar orbiter iv probe in this study we map in detail the morphology of each distinct facies observed within the orientale ejecta blanket using high resolution lunar reconnaissance orbiter lro wide angle camera wac and narrow angle camera nac images and lunar orbiter laser altimeter lola elevation data we identified 5 unique facies within the ejecta blanket facies a is identified as a region of hummocky plains located in a low lying topographic region between the outer rook and cordillera rings this facies is interpreted to be a mix of crater derived impact melt and km scale blocks of ballistic ejecta and host rock broken up during the modification stage and formation of the cordillera ring facies b is an inner facies marked by radial grooves extending outward from the direction of the basin center this facies is interpreted as the continuous ballistic ejecta blanket facies c consists of inner and outer groupings of flat smooth surfaced deposits isolated in local topographic lows facies d displays characteristic sinuous ridges and lobate extensions facies c and d are interpreted to be impact melt rich materials which manifest as flows and ponds our observations suggest that these facies were emplaced subsequent to the ballistic ejecta blanket most likely during the modification stage of crater formation and flowed and ponded in topographically low lying regions facies e consists of distinct crater chains emanating radially from the basin center and extending from 700 to 1000 km from the center of orientale this facies is considered to be chains of secondary craters formed from large blocks of ballistic ejecta our mapping effort shows that the individual ejecta facies were influenced and controlled to varying degrees by pre existing slopes and topography at the basin scale the overall downslope direction toward the lunar lowlands to the east and southeast of the basin center resulted in large impact melt flows 100 s of kilometers in length while the regional upslope trends in the west and northwest inhibited the development of extensive impact melt flows on a smaller scale it can be observed that ground hugging ejecta collected behind and flowed around high topographic obstacles while diverting into topographic low regions e g around uplifted pre existing crater rims but down into pre existing crater floors the dispersion of the various ejecta facies mapped here also indicates both a direction and an angle for the impact event that formed orientale basin the bilateral distribution of both ballistic and impact melt rich ejecta deposits across a line running northeast southwest suggests the impact occurred from the northeast toward the southwest careful mapping of the secondary impact crater chains facies e shows the development of a forbidden zone lacking these impacts to the northeast as well as a concentration of the longest secondary crater chains to the northwest and southeast perpendicular to the aforementioned line of bilateral ejecta distribution this distribution of secondary impact craters contrasts with the circularity of the basin and suggests that orientale basin was formed by 25 45 impact from the northeast

recent sea level change in the mediterranean sea revealed by topex poseidon satellite altimetry using altimetry data of the topex poseidon satellite available since early 1993 we show that the eastern mediterranean sea level has been continuously rising during 1993 1999 at a rate up to 20 mm yr southeast of crete sea level rise is also observed in the algerian provencal basin as well as in the tyrrhenian and adriatic seas the north ionian sea on the other hand shows an opposite trend i e a sea level drop during the past seven years sea surface temperature trends are strongly correlated to sea level trends indicating that at least part of the observed sea level change has a thermal origin the recent mediterranean sea level rise observed by topex poseidon may be related to the warming trends reported from hydrographic cruises in the intermediate and deep waters of the eastern basin since the early 1990s and of the western basin since the 1960s

martian gullies a comprehensive review of observations mechanisms and insights from earth analogues upon their discovery in 2000 martian gullies were hailed as the first proof of recent i e less than a few million years flowing liquid water on the surface of a dry desert planet many processes have been proposed to have formed martian gullies ranging from liquid water seepage from aquifers melting of snow ice and frost to dry granular flows potentially lubricated by co2 terrestrial analogues have played a pivotal role in the conception and validation of gully formation mechanisms comparison with the terrestrial landscape argues for gully formation by liquid water debris flows originating from surface melting however limited knowledge of sediment transport by sublimation is a critical factor in impeding progress on the co2 sublimation hypothesis we propose avenues towards resolving the debate a laboratory simulations targeting variables that can be measured from orbit b applications of landscape evolution models c incorporation of the concept of sediment connectivity d using 3d fluid dynamic models to link deposit morphology and flow rheology and e a more intense exchange of techniques between terrestrial and planetary geomorphology including quantitative and temporal approaches finally we emphasize that the present may not accurately represent the past and that martian gullies likely formed by a combination of processes

improved satellite altimetry in coastal systems case study of the corsica channel mediterranean sea 1 the fidelity of corrections and processing are critical for a realistic use of official altimetric products close to the coast a new processing strategy which starts from the topex poseidon gdrs with the addition of improved corrective terms is proposed and evaluated in the area of the corsica channel sea level anomalies agree with the coincident sea truth bottom pressure and tide gauge within 2 3 cm rms for seasonal and longer time scales analysis for almost ten years of coincident mooring and altimetric velocities shows that a substantial reduction of uncertainty to 4 cm s 1 may be possible after reasonable filtering of the noise introduced by more variable coastal sea surface states the conclusion is that the altimetry success is still limited to seasonal time scales and provided that the oceanographic signal ensures an adequate signature to be isolated from background noise

the equilibrium size frequency distribution of small craters reveals the effects of distal ejecta on lunar landscape morphology abstract small craters of the lunar maria are observed to be in a state of equilibrium in which the rate of production of new craters is on average equal to the rate of destruction of old craters crater counts of multiple lunar terrains over decades consistently show that the equilibrium cumulative size frequency distribution sfd per unit area of small craters of radius r is proportional r 2 and that the total crater density is a few percent of so called geometric saturation which is the maximum theoretical packing density of circular features while it has long been known that the primary crater destruction mechanism for these small craters is steady diffusive degradation there are few quantitative constraints on the processes that determine the degradation rate of meter to kilometer scale lunar surface features here we combine analytical modeling with a monte carlo landscape evolution code known as the cratered terrain evolution model to place constraints on which processes control the observed equilibrium size frequency distribution for small craters we find that the impacts by small distal ejecta fragments distributed in spatially heterogeneous rays is the largest contributor to the diffusive degradation which controls the equilibrium sfd of small craters other degradation or crater removal mechanisms such cookie cutting ejecta burial seismic shaking and micrometeoroid bombardment likely contribute very little to the diffusive topographic degradation of the lunar maria at the meter scale and larger

the western mediterranean deep water a proxy for climate change reconstructions of mediterranean ocean temperature fields back to 1950 show a proxy relationship between heat content changes in the north atlantic and the western mediterranean deep water wmdw formed in the gulf of lions in winter because of consistent air sea heat fluxes over these areas strongly correlated to the north atlantic oscillation nao

sampling bias of discontinuity orientation caused by linear sampling technique abstract orientation data of discontinuities are of paramount importance for rock slope stability studies because they control the possibility of unstable conditions or excessive deformation most orientation data are collected using linear sampling techniques such as borehole fracture mapping and the detailed scanline method outcrop mapping however data acquired by such linear sampling techniques are subject to bias owing to the orientation of the sampling line even if a weighting factor is applied to orientation data to reduce this problem the bias will not be significantly reduced when certain sampling orientations are involved if the linear sampling orientation nearly parallels the discontinuity orientation most of these parallel discontinuities will be excluded from the survey results this phenomenon can cause serious misinterpretation of discontinuity orientation data because critical information is omitted in the case study orientation data collected using the borehole fracture mapping method vertical were compared to those based on orientation data from the detailed scanline method horizontal scanline differences in results for the two procedures revealed a concern that a representative orientation of discontinuities was not accomplished equal area polar stereo nets were used to determine the distribution of dip angles and to compare the data distribution for the borehole method with that for the outcrop scanline

impact fragmentation of lonar crater india implications for impact cratering processes in basalt impact fragmentation is an energetic process that has affected all planetary bodies to understand its effects in basalt we studied lonar crater which is a rare terrestrial simple impact crater in basalt and analogues to kilometer scale simple craters on mars the lonar ejecta consists of basaltic fragments with sizes ranging from silt to boulder the cumulative size and mass frequency distributions of these fragments show variation of power index for different size ranges suggesting simple and complex fragmentation the general shape of the fragments is compact platy bladed and elongated with an average edge angle of 100 the size distribution of cobble to boulder sized fragments is similar to the fracture spacing distribution in the upper crater wall indicating the provenance of those large fragments its consistency with a theoretical spallation model suggests that the large fragments were ejected from near surface of the target whereas the small fragments from deeper level the petrophysical properties of the ejecta fragments reflect the geophysical heterogeneity in the target basalt that significantly reduced the original size of spall fragments the presence of fe mg phyllosilicates smectites both in the ejecta and wall indicates the role of impact in excavating the phyllosilicates from the interior of basaltic target affected by aqueous alteration the seismic images reveal a thickness variation in the ejecta blanket segregation of boulders fractures and faults in the bedrock beneath the crater rim the fracturing fragmentation and fluvial degradation of lonar crater have important implications for mars

the seasonal characteristics of the circulation in the north mediterranean basin and their relationship with the atmospheric climatic conditions the greater heat losses sustained by the ligurian provencal basin in winter appear to be the major factor leading to the periodic intrusions of the warmer tyrrhenian water from the east this is the main conclusion of a 3 year oceanographic investigation carried out in the eastern ligurian provencal basin in order to monitor the long term characteristics of its exchanges with the tyrrhenian sea the analysis of the whole data set collected in this period shows that two currents converge north of corsica after having flowed along the northwestern side of corsica the west corsican current and through the corsican channel the tyrrhenian current while the former does maintain nearly steady properties year round the latter crosses the strait only during the coldest season thus showing a clear seasonal trend that begins again every year the comparison with the meteorological parameters of the ligurian provencal basin indicates that the winter intrusions of the tyrrhenian current are tightly associated with the heat and water losses through the rise induced in the upper basin density in addition to reintegrating the heat lost to the atmosphere the tyrrhenian flow might also restore the volume of the basin upper layer involved in the deep water formation processes this enables us to infer that a unique circulation pattern mostly driven by atmospheric climatic conditions involves the northern part of the western mediterranean sea

granular avalanches on the moon mass wasting conditions processes and features seven lunar crater sites of granular avalanches are studied utilizing high resolution images 0 42 1 3 m pixel from the lunar reconnaissance orbiter camera one in kepler crater is examined in detail all the sites are slopes of debris extensively aggraded by frictional freezing at their dynamic angle of repose four in craters formed in basaltic mare and three in the anorthositic highlands diverse styles of mass wasting occur and three types of dry debris flow deposit are recognized 1 multiple channel and lobe type with coarse grained levees and lobate terminations that impound finer debris 2 single surge polylobate type with sub parallel arrays of lobes and fingers with segregated coarse grained margins and 3 multiple ribbon type with tracks reflecting reworked substrate minor levees and no coarse terminations the latter type results from propagation of granular erosion deposition waves down slopes dominantly of fine regolith and it is the first recognized natural example dimensions architectures and granular segregation styles of the two coarse grained deposit types are like those formed in natural and experimental avalanches on earth although the timescale of motion differs due to the reduced gravity influences of reduced gravity and fine grained regolith on dynamics of granular flow and deposition appear slight but we distinguish for the first time extensive remobilization of coarse talus by inundation with finer debris the few sites show no clear difference attributable to the contrasting mare basalt and highland megaregolith host rocks and their fragmentation this lunar study offers a benchmarking of deposit types that can be attributed to formation without influence of liquid or gas

the seismically active lobate scarps and coseismic lunar boulder avalanches triggered by 3 january 1975 mw 4 1 shallow moonquake

recent seismicity in valles marineris mars insights from young faults landslides boulder falls and possible mud volcanoes abstract current seismicity of mars is poorly known geodynamic models and analysis of surface faults indicate that mars could be seismically active globally particularly within the tharsis region however published geologic constraints on such activity are sparse in this study we use geomorphologic observations and crater size frequency age determinations gleaned from high resolution orbiter data to demonstrate that the valles marineris region is recently seismo tectonically active the chasmata shows evidence of reactivated dip slip faults that cross cut the chasmata walls and floors and indicates up to 1 2 km total vertical displacement along the trough bounding faults more than 16000 boulder fall occurrences with pristine trails are observed throughout the chasmata wall with an average slope of 25 degrees the boulder falls are interpreted to have been triggered by recent seismic shaking from the shallow marsquakes occurring along the chasmata faults possibly in the last thousands of years synthetic ground motion models indicate several m w 4 6 marsquakes at shallow depths 1 6 km are required to produce these canyon wide boulder falls in addition the presence of many young landslides 22 790 ma proximal to the reactivated trough bounding faults and formation of thousands of possible mud volcanic cones throughout the chasmata floor all suggest marsquake triggered shaking in the past tens to hundreds of million years corresponding to late to middle amazonian epochs we estimate formation of 20 m to 1 3 km diameter fresh impact craters around the chasmata had negligible contribution to the recent seismicity therefore valles marineris tectonism is an important source of marsquakes that may be readily detectable by the upcoming insight seismometers

effects of soil spatial variability at the hillslope and catchment scales on characteristics of rainfall induced landslides spatial variations in soil properties affect key hydrological processes yet their role in soil mechanical response to hydro mechanical loading is rarely considered this study aims to fill this gap by systematically quantifying effects of spatial variations in soil type and initial water content on rapid rainfall induced shallow landslide predictions at the hillslope and catchment scales we employed a physically based landslide triggering model that considers mechanical interactions among soil columns governed by strength thresholds at the hillslope scale we found that the emergence of weak regions induced by spatial variations of soil type and initial water content resulted in early triggering of landslides with smaller volumes of released mass relative to a homogeneous slope at the catchment scale initial water content was linked to a topographic wetness index whereas soil type varied deterministically with soil depth considering spatially correlated stochastic components results indicate that a strong spatial organization of initial water content delays landslide triggering whereas spatially linked soil type with soil depth promoted landslide initiation increasing the standard deviation and correlation length of the stochastic component of soil type increases landslide volume and hastens onset of landslides the study illustrates that for similar external boundary conditions and mean soil properties landslide characteristics vary significantly with soil variability hence it must be considered for improved landslide model predictions

geomorphological evidence for transient water flow on vesta abstract vesta the second most massive asteroid has long been perceived as anhydrous recent studies suggesting the presence of hydrated minerals and past subsurface water have challenged this long standing perception yet direct geologic indications of water activity on vesta s surface were unexpected herein we show evidence that transient water flowed on the surface in a debris flow like process and left distinctive geomorphologic features based on detailed analysis of highest resolution 20 m pixel images obtained by the dawn spacecraft we identify a class of locally occurring interconnected and curvilinear gully networks on the walls of young

crater degradation on the lunar maria topographic diffusion and the rate of erosion on the moon landscape evolution on the moon is dominated by impact cratering in the post maria period in this study we mapped 800 m to 5 km diameter craters on 30 of the lunar maria and extracted their topographic profiles from digital terrain models created using the kaguya terrain camera we then characterized the degradation of these craters using a topographic diffusion model because craters have a well understood initial morphometry these data provide insight into erosion on the moon and the topographic diffusivity of the lunar surface as a function of time the average diffusivity we calculate over the past 3 ga is 5 5 m2 myr with this diffusivity after 3 ga a 1 km diameter crater is reduced to approximately 52 of its initial depth and a 300 m diameter crater is reduced to only 7 of its initial depth and craters smaller than 200 300 m are degraded beyond recognition our results also allow estimation of the age of individual craters on the basis of their degradation state provide a constraint on the age of mare units and enable modeling of how lunar terrain evolves as a function of its topography

large rock slides in impact craters on the moon and mercury abstract impact craters are the most common surface features on the moon and mercury on these two bodies we recognized and mapped large landslides on the walls of impact craters through visual inspection of high resolution imagery we compiled an inventory of 60 landslides on the moon and a second inventory of 58 landslides on mercury adopting categories used to catalog terrestrial mass movements we classified the landslides on the moon and mercury as rock slides we determined the probability density distribution of their planimetric area and we compared the distributions with similar distributions for terrestrial and martian landslides using data from the literature we found that rock slides mapped in impact craters on the moon are on average larger than analogous rock slides on mercury the relationship between the area of the individual rock slides and the area of the hosting crater suggests that rock slides on mercury initiate in smaller craters we hypothesize that the above findings are an effect of the weaker surface gravity of the moon compared to that of mercury and or an effect of the rock material properties

lagrangian and eulerian observations of the surface circulation in the tyrrhenian sea 1 this paper focuses on the study of the tyrrhenian sea a subbasin of the western mediterranean whose surface and near surface dynamics are still relatively poorly known in particular its southern region its circulation is described first by a set of 53 surface drifters deployed in the area between december 2001 and february 2004 in order to supplement the drifter data with continuously and uniformly sampled observations and to characterize the seasonal as well as higher frequency variability of the surface circulation the lagrangian analysis was associated to simultaneous satellite remotely sensed altimeter covering the period 2001 2004 the investigation was based on trajectory analysis and on the computation of the pseudo eulerian statistics using the same binning and space time averaging for drifter and altimeter data the data reveal a complex pattern of the circulation especially in the southern region of the tyrrhenian dominated by semipermanent recirculations and transient features which sometimes makes it difficult to identify a consistent mean flow while the northern subbasin is characterized by a pair composed of cyclonic and anticyclonic circulations known in the literature as the north tyrrhenian cyclone and north tyrrhenian anticyclone the pseudo eulerian statistics computed with the two data sets evidenced the representativeness of a joint analysis of altimeter and drifter data and yielded useful indications about proper preliminary preprocessing and resampling procedures so as to make the comparison statistically sound

the south pole region of the moon as seen by clementine the clementine mission has provided the first comprehensive set of high resolution images of the south pole region of the moon within 5 of latitude of the pole an area of an estimated 30 000 square kilometers remained in shadow during a full lunar rotation and is a promising target for future exploration for ice deposits the schrodinger basin 320 kilometers in diameter centered at 75 s is one of the two youngest least modified great multiring impact basins on the moon a large maar type volcano localized along a graben within the schrodinger basin probably erupted between 1 and 2 billion years ago

model tests on flow slide of lunar regolith simulant a significant fraction of lunar exploration is concerned with the lunar regolith over the last three decades theoretical and experimental effort has been directed towards investigating the mechanical parameters and chemical composition of lunar regolith however the properties of lunar regolith flow have received only limited attention even though there have been reports of lunar avalanches in this paper the flow evolution of a lunar regolith simulant at various inclined angles was investigated in a rectangular shaped flume constructed of plexiglas the objective of this paper is to study the flow patterns of lunar regolith simulant by using a fast shutter speed 1 140 s ccd camera 640 480 pixels configurations of the flow under the action of different chute angles are captured in addition the engineering strains of the different chute angles are also calculated the research results help to investigate the real lunar regolith flow slide to some extent

a hydrological analysis of terrestrial and martian gullies implications for liquid water on mars abstract understanding the role and amounts of liquid water involved in martian gully formation is critical in studies of the martian hydrosphere and climate we performed hydrological analyses using the manning and darcy weisbach equations in order to infer flow velocities and discharge rates from channels at two gully sites in noachis terra mars the results of these analyses were compared with analogous hillside gullies in australia we found the velocities and discharge rates for the terrestrial gullies to be comparable to velocities and discharge rates of some small martian gully channels in contrast velocity and discharge in some larger martian gullies were almost an order of magnitude higher equating with catastrophic flows on earth we postulate that the larger gully channels were more likely formed by a number of smaller flows in a similar manner observed in some terrestrial gullies a scenario that does not require vast amounts of liquid water to be stable under martian conditions in addition we found that post fluvial channel widening may have acted on the martian gullies probably by dry mass wasting leading to larger channels than were originally carved by liquid water future hydrological analyses of martian gullies will lead to a greater understanding of the relative importance of dry mass wasting compared to liquid water erosion

probabilistic analysis of seepage that considers the spatial variability of permeability for an embankment on soil foundation abstract in this study probabilistic analysis of seepage through an embankment on soil foundation was performed the traditional seepage analysis method was extended to develop a probabilistic approach that accounts for the uncertainties and spatial variation of the hydraulic conductivity in a layered soil profile the hydraulic conductivity of soil shows significant spatial variations in different layers because of stratification further it varies on a smaller scale within each individual layer it was assumed that the statistics of the hydraulic conductivity is different for different layers and that the hydraulic conductivity in a layer is uncorrelated with that in the other layers two dimensional random fields were generated on the basis of the karhunen loeve expansion in a manner consistent with a specified marginal distribution function and an autocorrelation function a series of seepage analyses of embankment foundation systems were performed using the generated random fields to study the effects of uncertainty due to the spatial heterogeneity of the hydraulic conductivity on the seepage flow the results showed that the probabilistic framework can be used to efficiently consider the various flow patterns caused by the spatial variability of the hydraulic conductivity in seepage assessment for an embankment on soil foundation

a beach ridge progradation complex reflecting periodical sea level and climate variability during the holocene gulf of almeria western mediterranean detailed mapping based on aerial photographs at various scales analysis of morpho sedimentary units and radiocarbon dating of the prograding beach ridge complex of campo de dalias almeria allow the differentiation of six prograding units these are called h1 7400 6000 cal bp h2 5400 4200 cal bp h3 4200 3000 cal bp h4 2700 1900 cal bp h5 1900 1100 cal bp and h6 500 cal bp present h units are deposited during periods of high relative sea level and increased sediment input to the coast they are bounded by large swales or erosional surfaces associated with lower sea levels and reduced input of sediment to the coast these correspond to short periods of increased aridity inside the general arid trend recorded in the western mediterranean since 5 4 ka changes in the flux of atlantic superficial waters into the mediterranean sea and relative strength of the w sw winds account for the recorded oscillations of relative sea level we deduce a decadal periodicity for the deposition of a beach ridge and the adjacent swale and suggest that it is related to fluctuations of the north atlantic oscillation nao index and to variations of solar activity the duration of h units shows a quasi millennial periodicity punctuated by short hundred years episodes of reduced progradation or erosion representing events of increased aridity likely to be related to bond s holocene cold events

influence of spatial variability of soil young s modulus on tunnel convergence in soft soils abstract field data have shown the fact that soil spatial variability could aggravate the uncertainty of tunnel convergence d a key indicator for serviceability and safety of tunnels this paper presents a detailed numerical analysis to investigate the probabilistic response of tunnel convergence in spatially varied soft soils the soil young s modulus es is highlighted and modeled with isotropic and horizontally stratified anisotropic random fields respectively the influence of scale of fluctuation sof of the es on convergence d is discussed in detail with respect to different directions i e the vertical and horizontal directions both for and d it is observed that ignoring the spatial variability of es i e disregarding the possibility of unfavorable soft soil low stiffness soil locally around tunnel can underestimate the mean value of d the horizontally stratified anisotropic random field is more appropriate than isotropic random field in the sense of an accurate prediction especially when extreme tunnel convergence occurs in horizontally stratified anisotropic random fields the influence of horizontal and vertical sof is different on tunnel convergence the surrounding soils near tunnel crown and invert or across tunnel horizontal diameter are very critical to the tunnel convergence in addition the effect of horizontal sof x on failure probability of the calculated d exceeding the specified allowable dlim is limited when the x is larger than 4 84 times of tunnel outer diameter

geologic map of the northern hemisphere of vesta based on dawn framing camera fc images abstract the dawn framing camera fc has imaged the northern hemisphere of the asteroid 4 vesta at high spatial resolution and coverage this study represents the first investigation of the overall geology of the northern hemisphere 22 90 n quadrangles av 1 2 3 4 and 5 using these unique dawn mission observations we have compiled a morphologic map and performed crater size frequency distribution csfd measurements to date the geologic units the hemisphere is characterized by a heavily cratered surface with a few highly subdued basins up to 200 km in diameter the most widespread unit is a plateau cratered highland unit similar to although of lower elevation than the equatorial vestalia terra plateau large scale troughs and ridges have regionally affected the surface between 180 e and 270 e these tectonic features are well developed and related to the south pole veneneia impact saturnalia fossae trough unit elsewhere on the hemisphere they are rare and subdued saturnalia fossae cratered unit in these pre rheasilvia units we observed an unexpectedly high frequency of impact craters up to 10 km in diameter whose formation could in part be related to the rheasilvia basin forming event the rheasilvia impact has potentially affected the northern hemisphere also with s n small scale lineations but without covering it with an ejecta blanket post rheasilvia impact craters are small

the role of straits and channels in understanding the characteristics of mediterranean circulation abstract straits in the mediterranean sea form an important network from which one can determine the characteristics of the water exchange between all the constituent sub basins this includes the definition of water masses and water transport and their time variability from 1994 all the major straits in the mediterranean sea gibraltar sicily otranto balearic sea straits cretan arc straits and corsica were subject to long term observations as part of various research projects besides adding new elements to the knowledge of internal strait conditions the data sets collected allow us to propose a fairly consistent representation of the mediterranean circulation and budgets in key points within the basin the amplitude of the annual water transport measured at these straits was about 1 sv and it appears to be modulated by a significant low frequency and seasonal variability for the first time a seasonal component was identified at gibraltar thus raising new questions on the actual state of the mediterranean also the very likely existence of a significant interannual component was documented in the corsica channel this component was found to be related to the interannual variability of the north atlantic oscillation the observations in the cretan arc straits have provided a more comprehensive representation of the recent changes in the eastern mediterranean thermohaline cell it is noteworthy that the effects of these changes have been observed both in the otranto and sicily straits and are now affecting the adjacent sea regions the presence of a stream of modified atlantic water in the balearic sea channels indicates that part of the atlantic inflow may be diverted directly into the northern region of the western mediterranean finally data gathered in the sardinia channel indicate that the central mediterranean region plays a critical role in controlling exchanges between the eastern and the western mediterranean while it is emphasized that the tyrrhenian sea area plays a role in strongly modifying some of the water masses that contribute to the large scale basin circulation their mixing creates new water types which modify the currently known pattern and composition of the mediterranean circulation

multi agent gully processes evidence from the monaro volcanic province australia and in terra cimmeria mars abstract comparison of the similarities and differences between terrestrial and martian hillside gullies promotes understanding of how surface processes operate on both planets here we tested the viability of subsurface flow of water as a process affecting gully evolution we compared gullies within the monaro volcanic province near cooma new south wales australia to gullies possessing strong structural control near gasa crater terra cimmeria mars although cursory examination of the monaro gullies initially suggested strong evidence for aquifer erosion detailed field surveys showed the evidence to be ambiguous instead a complex regime of erosion dependent on multiple conditions and processes such as local geology surface runoff dry mass wasting and animal activity emerged we found the morphology of gullies near gasa crater to be consistent with erosion caused by liquid water while also being heavily influenced by the local environment including slope and geology additionally erosion at the martian site was not consistent with evidence of subsequent smaller scale erosion and channel modification by dry mass wasting local conditions thus play an important role in gully evolution further highlighting that processes forming martian gullies may be more diverse than initially thought

a sensitivity study of the general circulation of the western mediterranean sea part ii the response to atmospheric forcing abstract this paper investigates the influence of sea surface thermohaline fluxes and wind stress on the circulation of the western mediterranean sea using a high resolution 3d primitive equation model an 18 year experiment was forced with the daily output of a fine grid mesh numerical weather prediction model the major characteristics of the circulation are well reproduced the basin surface circulation is cyclonic over all of the basin the two anticyclonic alboran gyres are present the instabilities of the algerian current generate large anticyclonic eddies that invade the whole algerian basin the liguro provencal catalan current is well marked deep water convection down to the bottom only occurs during the first 3 years then winter intermediate water is produced the north south gradient of the atmospheric thermohaline fluxes induces a northward surface transport of water from the algerian basin into the liguro provencal basin this pattern can be associated with the balearic front sensitivity

a three dimensional numerical study of deep water formation in the northwestern mediterranean sea abstract deep water formation dwf in the northwestern mediterranean sea and the subsequent horizontal circulation are investigated in a rectangular basin with a three dimensional primitive equation model the basin is forced by constant climatological heat and salt fluxes convective motion is parameterized by a simple nonpenetrative convective adjustment process plus richardson number dependent vertical eddy viscosity and diffusivity a homogeneous column of dense water is progressively formed in the forcing area meanders of 40 km wavelength develop at the periphery of the column these features agree with observations energy studies show that the meanders are generated mainly through a baroclinic instability process these meanders and the associated cells of vertical motion contribute to the process of dwf they generate vertical advection while the associated horizontal advection tends to restratify the surface water of the column and thus to inhibit very deep convection just before the end o

imaging of lunar surface maturity the physical evolution of the lunar surface with exposure to the space environment is termed maturation and maturity is the degree to which a particular lunar soil possesses quantitative characteristics consistent with that exposure several quantitative measures or indices of maturity have been proposed and employed including the abundance of solar wind gas abundance of various types of agglutinates various measures of grain size and is feo among the changes attendant with space exposure are striking changes in the optical characteristics of soils mature lunar soils are dark red and exhibit reduced spectral contrast relative to immature soils this paper presents an optical maturity index that quantifies the spectral effects of maturation we show that this optical maturity index correlates with other maturity indices about as well as the accepted maturity indices correlate among themselves and is only weakly coupled to composition the modest correlations among maturity indices suggest important controls on individual maturity indices other than age uncorrelated variations in the rates of accumulation of individual indicators or variations in depths over which indicators are emplaced in addition to mixing these effects conspire to reduce the equivalence of maturity and duration of surface exposure optical maturity illustrates some of these effects showing that ejecta of large and small craters mature at different rates and that the interiors and ejecta of large craters exhibit systematically different optical maturities the same or analogous effects are likely to influence other maturity indices

structural effects of meteorite impact on basalt evidence from lonar crater india received 31 january 2005 revised 17 august 2005 accepted 26 august 2005 published 8 december 2005 1 lonar crater is a simple bowl shaped near circular impact crater in the 65 myr old deccan volcanic province in india as lonar crater is a rare terrestrial crater formed entirely in basalt it provides an excellent opportunity to study the impact deformation in target basalt which is common on the surfaces of other terrestrial planets and their satellites the present study aims at documenting the impact deformational structures in the massive basalt well exposed on the upper crater wall where the basalt shows upward turning of the flow sequence resulting in a circular deformation pattern three fracture systems radial concentric and conical fractures are exposed on the inner crater wall on the fracture planes plumose structures are common uplift and tilting of the basalt sequence and formation of the fractures inside the crater are clearly related to the impact event and are different from the preimpact structures such as cooling related columnar joints and fractures of possible tectonic origin which are observed outside the crater slumping is common throughout the inner wall and listric faulting displaces the flows in the northeastern inner wall the impact structures of lonar crater are broadly similar to those at other simple terrestrial craters in granites and clastic sedimentary rocks and even small scale experimental craters formed in gabbro targets as lonar crater is similar to the strength controlled laboratory craters impact parameters could be modeled for this crater provided maximum depth of fracture formation would be known citation kumar p s 2005 structural effects of meteorite impact on basalt evidence from lonar crater india j geophys res 110 b12402 doi 10 1029 2005jb003662

impact spallation processes on the moon a case study from the size and shape analysis of ejecta boulders and secondary craters of censorinus crater abstract impact spallation is a fundamental process responsible for formation of ejecta boulders from impact craters although theoretical spallation models were developed about three decades ago only limited geological observations have been made so far to test these models the 3 8 km censorinus crater on the moon provides an excellent opportunity for studying the impact spallation processes associated with a fresh simple crater formed by oblique impact using the lunar reconnaissance orbiter narrow angle camera images we prepared the ejecta boulder distribution map of censorinus crater and measured the boulder sizes and shapes mapping of about 242 000 ejecta boulders enabled us to document the size distribution of boulders both radial and concentric to the impact crater larger size boulders dominate the crater rim areas while they become smaller away from the crater the boulder distribution exhibits a radial asymmetry suggesting censorinus is a oblique impact in which the uprange ejecta have smaller ranges with larger concentration of boulders near the southwestern crater rim while the downrange ejecta are in general characterized by smaller boulders with high spatial dispersion the cumulative size frequency distribution csfd of boulders shows a highly variable fragmentation history in which the uprange boulders suffered more complex fragmentation the ejecta boulders also exhibit a variety of shapes that are gleaned from their axial ratios and edge angle characteristics there is a general decrease of axial ratios away from the crater rim rectangular boulders dominate the crater rim and they become more equant away from the crater in addition to the boulder sizes the boulder shape distribution also exhibits a mild asymmetry in response to the oblique impact small size fresh impact craters 84 000 craters are abundant on the censorinus ejecta and post date censorinus these craters are found in two morphologic types in which a large majority of craters have subdued ejecta rayless craters while some possess bright rayed ejecta bright rayed craters the csfd of rayless craters show a steep power law slope with a b value of 4 0 similar to the secondary craters produced by the impact of ejecta from primary craters we therefore interpret the rayless craters as the secondary craters of censorinus on the other hand the csfd of bright rayed craters have smaller power law slope b value 2 7 which is a characteristic of primary craters and thus provide 3 ma age for censorinus crater when the characteristics of censorinus boulders are compared with the theoretical spallation models that are sensitive to the petrophysical properties of the target lunar highland the models generally agree with the censorinus boulders however the observed shape and size characteristics of the censorinus boulders are found to be more complex than the theoretical spallation models the ejecta boulders suffered more complex fragmentation and asymmetric distribution in response to the oblique impact the spallation models accounting oblique impacts have not yet been developed therefore our censorinus boulder observations can be used to develop and validate the new theoretical spallation models for the effects of oblique impacts

volcanism on farside of the moon new evidence from antoniadi in south pole aitken basin abstract the lunar surface is characterized by asymmetric distribution of its volcanic deposits the nearside contains about 90 of the mare basalts while there are a few on the farside with some are in the south pole aitken spa basin which is the largest and oldest impact basin on the moon although the mare volcanism on the nearside of the moon has been very well characterized our understanding of the farside is relatively poor our geological mapping using lunar reconnaissance orbiter lro and chandrayaan 1 moon mineralogy mapper m3 data of 143 km antoniadi impact basin provides new insights into volcanic processes in the southern spa antoniadi has excavated the spa floor as deep as 9 km distribution of secondary craters around antoniadi shows that the basin was formed by oblique impact with the direction of 50 counter clockwise from 178 e longitude our geological mapping has found for the first time several volcanic cones 0 2 2 5 km diameter in association with the mare basalt flows as per morphological classification these are c e n and p type volcanic cones with abundant volcanic fragments in their summit areas the base and summit diameters of these cones are similar to those of marius hills on the nearside of the moon the cumulative size frequency distributions of the summit fragments provide a range of power index values between 3 and 9 suggesting the involvement of dynamic fragmentation of the volcanic materials during the eruptive processes the grabens in the basin floor show evidence for fissure eruption of the mare basalts the graben near the central peak exposes about 140 m thick basalt sequence containing a minimum of five individual lava layers the crater size frequency distributions of the mare deposits suggest an age of 1 6 ga for the flows in the central part of the basin while 2 6 ga for those on the outer floor near the basin wall indicating the episodic volcanism in the basin the young volcanism of 1 6 ga is reported for the first time from spa the m3 data reveal that the basin materials contain abundant low ca pyroxene while the mare basalts with high ca pyroxene we calculated the liquidus density of mare basalts based on feo and tio2 content which suggest a range of density from 2 7 to 2 8 g cm3 which would be lower than a gross lunar crust this would imply the emplacement of basaltic lavas through dikes by simple magma buoyancy or over pressurization of magma chambers if they present at the crust mantle boundary when the magma density is greater than the host crust the 1 6 ga old volcanism in antoniadi suggests that the mantle beneath the spa has been conducive for young magmatism possibly due to presence of kreep like material in the mantle

a 130 000 year record of levantine intermediate water flow variability in the corsica trough western mediterranean sea abstract sortable silt particle size data and stable isotope analyses from the corsica trough western mediterranean sea provide a continuous palaeoceanographic record of the inflow ventilation and vertical fluctuations of the levantine intermediate water liw in the northern tyrrhenian sea for the last 130 000 years the results presented herein reveal that climate changes drive the mediterranean intermediate circulation on milankovitch to millennial time scales intensified intermediate inflow and ventilation in the corsica trough occurred throughout the last glacial interval with a cold faster warm slower pattern existing between the dansgaard oeschger climatic oscillations including heinrich events and the liw variability by contrast a weak intermediate ventilation characterised the holocene and the last interglacial period especially during insolation maxima and the sapropel deposition in the eastern mediterranean this variability probably reflects the changes of the eastern mediterranean net evaporation as well as the propagation to the western mediterranean of the profound hydrographic adjustments of the levantine sea and adjacent areas to climate forcing the implications for the formation and ventilation of the western mediterranean deep water wmdw in the northwestern mediterranean basin as well as for mediterranean atlantic exchange through the strait of gibraltar are discussed

laboratory studies of two common saprolitic soils in hong kong two commonly encountered saprolitic soils in hong kong weathered volcanic tuff wt and weathered granite wg were studied using high quality intact samples the intact samples exhibited quasi preconsolidation pressure or yield stress under isotropic compression due to their bonded structures but the yield was progressive and not abrupt as the stress increased significant volumetric changes were measured these changes resembled clay type behavior the soils also exhibited anisotropic deformation under isotropic loading and unloading which was associated with the features of their parent rocks during the drained tests shearing at the in situ stress state produced peak strength and volumetric dilation undrained shearing showed complicated stress paths and dilatancy behavior in these soils phase transformation states and dilative shear failure were readily seen which resembles typical sand type behavior distinct shear band s appeared in the wt specimens during shearing whereas a bulging type of failure appeared in the wg specimens the soils ultimately approached the corresponding state guided by a unique critical state line regardless of their complex initial states in relation to the bonded structure and drainage conditions

the geology of 433 eros the global high resolution imaging of asteroid 433 eros by the near earth asteroid rendezvous near shoemaker spacecraft has made it possible to develop the first comprehensive picture of the geology of a small s type asteroid eros displays a variety of surface features and evidence of a substantial regolith large scale facets grooves and ridges indicate the presence of at least one global planar structure directional and superposition relations of smaller structural features suggest that fracturing has occurred throughout the object as with other small objects impact craters dominate the overall shape as well as the small scale topography of eros depth diameter ratios of craters on eros average 0 13 but the freshest craters approach lunar values of 0 2 ejecta block production from craters is highly variable the majority of large blocks appear to have originated from one 7 6 km crater shoemaker the interior morphology of craters does not reveal the influence of discrete mechanical boundaries at depth in the manner of craters formed on lunar mare regolith and on some parts of phobos this lack of mechanical boundaries and the abundant evidence of regolith in nearly every high resolution image suggests a gradation in the porosity and fracturing with depth the density of small craters is deficient at sizes below 200 m relative to predicted slopes of empirical saturation this characteristic which is also found on parts of phobos and lunar highland areas probably results from the efficient obliteration of small craters on a body with significant topographic slopes and a thick regolith eros displays a variety of regolith features such as debris aprons fine grained ponded deposits talus cones and bright and dark streamers on steep slopes indicative of efficient downslope movement of regolith these processes serve to mix materials in the upper loose fragmental portion of the asteroid regolith in the instance of ponded materials and crater wall deposits there is evidence of processes that segregate finer materials into discrete deposits the near observations have shown us that surface processes on small asteroids can be very complex and result in a wide variety of morphologic features and landforms that today seem exotic future missions to comets and asteroids will surely reveal still as yet unseen processes as well as give context to those discovered by the near shoemaker spacecraft

comparison of small lunar landslides and martian gullies some lunar crater wall landslides strongly resemble martian gullies despite the lack of geologically active water on the moon today or in the past the lunar features indicate that alcove channel apron morphology attributed on mars to seepage of liquid water can also form via a dry landslide mechanism therefore a more stringent test than just an alcove channel apron morphology is necessary to differentiate dry landslides from water carved gullies

lunar surface processes inferred from cosmogenic radionuclides in apollo 16 double drive core 68002 68001 abstract measurements of cosmogenic 10be 26al and 36cl in apollo 16 double drive core 68002 68001 are combined with a high resolution digital surface model of the sampling site to investigate the surface processes on the moon we find both a significant deficit of solar cosmic ray scr produced 26al and a lack of scr produced 36cl in the top 3 5 g cm2 of the lunar regolith the topographic model shows the core was taken from just inside a crater with a rim diameter of 25 30 cm these observations are consistent with regolith removal and displacement by a shallow impact that occurred on the order of 100 kyr ago or less our findings are also compatible with shallow mixing or gardening of the lunar regolith to depths of a few cm a value often found in other lunar cores over the 106 yr averaging times of 26al and 53mn measurements more definitive regolith mixing depth estimates are not possible due to the likelihood of disturbance in the top of the core as a result of sampling and or handling our results support the hypothesis that the lunar surface experiences more frequent disturbances by small primary and secondary impacts than has previously been assumed additionally we find no evidence that fine grained ejecta from the 2 0 myr old south ray crater impact reached this site if the layer of fine grained ejecta that reached the sampling site from the south ray crater was no more than a few cm thick this absence can be explained by the erosion that formed the small relatively recent crater at the coring location

u pb dating of mesozoic igneous rocks from hong kong twenty two new zircon and monazite u pb ages have been obtained for mesozoic plutonic and volcanic rocks of hong kong these have revealed the existence of four distinct periods of mid jurassic to lower cretaceous volcano plutonism 164 6 0 2 to 159 3 0 3 ma 146 6 0 2 to 146 2 0 2 ma 143 7 0 3 to 142 5 0 3 ma and 140 9 0 2 to 140 4 0 2 ma a concordant monazite age of 236 3 0 8 ma has also been obtained from one intrusive body representing the first known occurrence of a mid triassic granitoid in the territory among these rocks discordant u pb data projected to the concordia curve have given a broad range of inheritance ages from early phanerozoic to late archaean a xenocrystic zircon from one sample has yielded a concordant age of 1872 3 ma the new u pb ages have refined the results of recent rb sr whole rock age dating of the granitoid rocks and have considerably improved correlation between intrusive and extrusive units the occurrence of inherited components in many of the analysed rocks indicates that they were derived from or erupted through older crust containing a wide variety of age components either as primary igneous or detrital material

hydrographic characteristics of water masses and circulation in the northern ionian sea abstract the hydrography of intermediate and deep water masses in the northern ionian sea apulian plateau was studied through four quasi synoptic multidisciplinary surveys carried out in 2004 2006 as an ancillary oceanographic activity in the frame of the aplabes project this area plays a crucial role for the entire mediterranean basin being influenced by the water outflow of adriatic origin which under severe winter conditions is a primary source of dense water for the eastern mediterranean at the end of the 1980s such outflow showed a different behavior and only in the recent years has a gradual re establishing of the former condition been detected as such the adriatic sea has regained its role as a main source of the east mediterranean deep water which was temporarily inhibited during the well known eastern mediterranean transient which progressively modified the intermediate and deep layers of the mediterranean sea the general structure of water masses was similar through the investigated period but interesting differences within the bottom layer have been detected the interaction of the different water types present in the basin is reviewed by means of property property plots vertical sections isopycnal analyses and using an optimum multiparameter analysis omp which is an objective method to measure the mixing of water masses due to the lack of any direct information about the dynamics of the water column in the area of the apulian plateau during the whole analyzed period the classical method to infer the baroclinic velocity from the mass field has been applied to hydrographic data the well known indeterminacy of this method due to the barotropic component of the velocity field has been resolved using a short time series of current velocities acquired synoptically by a mooring located in the northern part of the studied area the wavelet transform was adopted for localizing and quantifying the variability of currents simultaneously in both frequency and time domains the presence of the adriatic deep water close to the bottom was detected on all four surveys with different signature as underlined by the objectively analysis with the optimum multiparameter analysis of the thermohaline field a core of cold less saline and oxygenated water of adriatic origin coming from the otranto channel was identified this water mass moved in geostrophic balance along the isobaths at 600 1000 m depth at the isopycnal surface of 29 18 kg m 3 not being dense enough to reach the deeper layers of the ionian basin carrying 0 27 0 36 sv

impact induced seismic activity on asteroid 433 eros a surface modification process high resolution images of the surface of asteroid 433 eros revealed evidence of downslope movement of a loose regolith layer as well as the degradation and erasure of small impact craters less than 100 meters in diameter one hypothesis to explain these observations is seismic reverberation after impact events we used a combination of seismic and geomorphic modeling to analyze the response of regolith covered topography particularly craters to impact induced seismic shaking applying these results to a stochastic cratering model for the surface of eros produced good agreement with the observed size frequency distribution of craters including the paucity of small craters

a possible influence of the north atlantic oscillation on the circulation of the western mediterranean sea a current time series spanning from 1985 to 1996 in the corsica channel shows that seasonal and interannual variabilities are stable components of the circulation of the northern part of the western mediterranean sea for the first time these characteristics are related to the state of the north atlantic oscillation during winter we have found that this large scale control is mainly maintained through the air sea interaction processes which take place in the northern basin these results provide new elements for a consistent explanation of the major features of the basin circulation such as the seasonal increase of the boundary current and deep water formation

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

analysis of regional gullies within noachis terra mars a complex relationship between slope surface material and aspect abstract the precise mechanisms by which martian hillside gullies erode and their dependence on the local environment remain subjects of debate we studied three sharp rimmed craters in noachis terra and 37 gully profiles using context camera ctx mars orbiter laser altimeter mola and high resolution stereo camera hrsc data we analysed the gully topographic profiles of seven gullies and nine dry ravines we measured slope properties using hrsc elevation data and used thermal inertia to infer material types of the gully sites we compared these with three nearby noachian age craters possessing crater wall slope angles within the range of previously observed gully formations in line with previous findings on individual gullies we found that the slope angles of gullies in our study area consistently reflect the inherited slope angles of the host escarpment suggesting that traditional slope based evidence of fluvial activity in martian gullies needs to be placed in context of its local environment we also observed a direct relationship between gully morphology and local composition of surface units martian gully features and possibly method of erosion appeared heavily influenced by changes in underlying geology and presence of erodible sediment examples included gully shape changing in accordance with type of erodible sediment we suggest that the degraded rims of gully free noachian craters precluded slope angles high enough to trigger creation of precursors to alcoves through mass wasting lack of these hollows has probably prevented the accumulation of enough ice rich sediment for gullies to form in our analysis reveals that there is a complex interdependence between slope processes and the local environment and global martian gully models may not work at the local scale

impact fracturing and structural modification of sedimentary rocks at meteor crater arizona 1 meteor crater provides a rare opportunity to study impact deformation of sedimentary target rocks and isolate those features from preexisting tectonic deformation and impact generated reactivation of preexisting tectonic features this study reports over 2500 new measurements of orientations of bedding faults and fractures in crater walls and in surrounding bedrock target rocks are characterized by horizontal bedding planes that are cut by at least three prominent sets of preimpact tectonic fracture systems the crater rim is also cut by three distinct groups of fractures radial concentric and conical fractures when the crater rim is restored to preimpact condition the radial and concentric fractures resemble preimpact fracture populations indicating that crater wall deformation and rim uplift were partly accommodated by activation of preexisting fractures in contrast the conical fractures are dissimilar to the preimpact fractures and apparently formed as a direct result of impact deformation some of the preimpact fractures were transformed into tear faults during the impact event and motion along those faults appears to have controlled the geometry of the impact deformational features the crater rim is thus square in plan view rather than circular faults occurring in the crater diagonals are prominent ones allowing greater vertical displacement the deformation pattern of meteor crater is different from that at lonar crater which was excavated in basalt with fewer preimpact fractures the differences between deformation at meteor crater and lonar crater may reflect the same disparities seen in simple craters produced in different target lithologies on mars and other planetary surfaces

olivine rich exposures in the south pole aitken basin abstract the distribution and the geological context of the olivine rich exposures in the south pole aitken spa basin on the moon were investigated based on the spectral data obtained from the spectral profiler sp and multiband imager mi onboard the japanese lunar explorer kaguya selene the olivine rich exposures are found only in the peak rings or central peaks of the schrodinger basin and zeeman crater which are located in the outer region of the spa basin and not in the center region on a localized scale the olivine rich materials are exposed on landslide features on the crater walls or sloped wall of the central peaks or the peak rings another observational finding is the co existence of olivine rich and plagioclase rich materials on a kilometer scale spanning most of the olivine rich sites in the schrodinger basin pyroxene rich materials are found in fresh craters outside the peak rings or the central peaks with olivine rich materials based on these results the following scenario are proposed 1 the impact to form the spa basin melted a large amount of the lunar upper mantle and crust and distributed the melted materials to the outer region 2 local differentiation of melted materials hid the olivine rich materials in the center region of the spa basin 3 later impacts that formed the schrodinger and zeeman craters excavated and exposed the olivine rich materials to the surface again and 4 space weathering and regolith gardening obscured the olivine rich spectra at the exposure sites but recent small scale impacts or landslides on the sloped wall exposed fresh olivine rich materials allowing the identification of the olivine rich exposures by spectral remote sensing this suggests that several different scale events play an important role in forming the surface distributions of originally deep seated materials on the moon as well as on other planetary bodies

spatial variability of saprolitic soil properties and relationship with joint set orientation of parent rock insights from cases in hong kong abstract geomaterials are known to be associated with significant heterogeneity and the natural variations in properties can affect the occurrence of landslides and failure of engineering structures while these variations are often observed to be spatially correlated the correlation patterns and their relationships with the geological origins of the materials are not well understood this study utilizes a three dimensional spatial variability model to investigate the correlation features in mechanical properties of saprolitic soils which are products of chemical weathering of granite rigorous geostatistical analyses are performed for soil test data at four locations in hong kong each also consisting of extensive rock joint survey information the analyses show that the principal directions of spatial variability in saprolitic soils correlate well with joint set orientations in the parent rock providing quantitative evidence that soil heterogeneity partly arises from the different rates of weathering along various directions relative to the rock discontinuities

geologic settings of martian gullies implications for their origins 1 martian gullies are found on steep slopes of all origins on all sorts of terrains of all ages scattered across nearly all of mars gullies are observed on all manner of substrates layered massive shattered rubble with or without nearby mantling deposits gullies are most common in the southern midlatitudes but also occur in the northern hemisphere in near polar terrain on equatorial volcanoes and on northern plains most gullies in the southern hemisphere are on south facing slopes but they occur on slopes of all orientations gullies are among the youngest features on mars but locally are overlain by eolian deposits and cut by faults old or eroded gullies are rare and those found have been partially stripped from slopes leaving no rock debris behind most gully deposits contain no detectable rocks these data are inconsistent with published hypotheses of gully formation including seeps and breakouts of water or brine hydrothermal activity cryovolcanism and breakouts from liquid carbon dioxide the data are consistent with gullies being dry flows of eolian material dust and silt comparable to climax snow avalanches on earth eolian sedimentation should be correlated little with underlying geology cause of slope age of terrain type of terrain or the nature of the rocks eolian sedimentation should be correlated with wind deceleration which will cause suspended sediment to drop and areas with common gullies are those with strong wind deceleration predicted by global circulation model in such areas sediment will be deposited preferentially in the lee of obstacles for the gully rich areas of the southern midlatitudes winds blow from the nnw so that sediment is deposited on sse facing slopes i e poleward these predictions are in accord with observations