the petrology geochemistry and age of lunar regolith breccias miller range 090036 and 090070 insights into the crustal history of the moon meteorites ejected from the surface of the moon as a result of impact events are an important source of lunar material in addition to apollo and luna samples here we report bulk element composition mineral chemistry age and petrography of miller range mil 090036 and 090070 lunar meteorites mil 090036 and 090070 are both anorthositic regolith breccias consisting of mineral fragments and lithic clasts in a glassy matrix they are not paired and represent sampling of two distinct regions of the lunar crust that have protoliths similar to ferroan anorthosites 40ar 39ar chronology performed on two subsplits of mil 090070 33 a pale clast impact melt and a dark glassy melt component shows that the sample underwent two main degassing events one at 3 88 ga and another at 3 65 ga the cosmic ray exposure data obtained from mil 090070 are consistent with a short 8 9 ma exposure close to the lunar surface bulk rock feo tio2 and th concentrations in both samples were compared with 2 degree lunar prospector gamma ray spectrometer lp grs data sets to determine areas of the lunar surface where the regolith matches the abundances observed on the sample we find that mil 090036 bulk rock is compositionally most similar to regolith surrounding the procellarum kreep terrane whereas mil 090070 best matches regolith in the feldspathic highlands terrane on the lunar farside our results suggest that some areas of the lunar farside crust are composed of ferroan anorthosite and that the samples shed light on the evolution and impact bombardment history of the ancient lunar highlands

do critical stresses for incipient motion and erosion really exist the concept of critical stress for the initial motion of noncohesive sediment beds under turbulent flow conditions is reviewed observational definitions of incipient motion are many and not entirely compatible some laboratory flume observations of sediment movement suggest that no true threshold exists current understanding of turbulent fluid motion at a sediment bed suggests that some particle movement must occur at all nonzero time mean velocities a combined model for flume flow and sediment transport having no threshold is seen to explain features of data that have been previously used to support the threshold concept

the effects of vegetative ash on infiltration capacity sediment transport and the generation of progressively bulked debris flows abstract through the alteration of the physical characteristics of a landscape such as the destruction of vegetation and the formation of a hydrophobic layer a fire can dramatically amplify erosion rates on the basis of field observations it has been proposed that the deposition of a layer of ash on the ground surface can enhance the erosion of mountainous terrain by surface runoff and might even be a necessary condition for the generation of progressively bulked debris flows in this study a flume was constructed to investigate the role of ash in increasing both the volume and the transport capacity of runoff the experiments demonstrated that the presence of ash on the soil surface reduces the ability of flowing water to infiltrate this effect is even greater when the ash has been pre wetted in addition the ability of ash slurries to infiltrate decreases with increasing ash concentration the results also indicate that the transport capacity of runoff is enhanced by the incorporation of ash into the flow because of the increased fluid density however the addition of ash reduces the boundary reynolds number such that at high ash concentrations and with fine grained sediment sediment transport declines as the flow becomes hydraulically smooth the experimental results were also used to evaluate the ability of steep flow fronts a common characteristic of debris flows and flash floods to increase sediment transport rates finally it is proposed that ash slurries may evolve into progressively bulked debris flows through a positive feedback between fluid density transport capacity and erosivity

infiltration on sloping terrain and its role on runoff generation and slope stability abstract a modified green and ampt model is formulated to quantify infiltration on sloping terrain underlain by homogeneous soil wetted by surficial water application this paper s theory for quantifying infiltration relies on the mathematical statement of the coupled partial differential equations pdes governing infiltration and runoff these pdes are solved by employing an explicit finite difference numerical method that yields the infiltration the infiltration rate the depth to the wetting front the rate of runoff and the depth of runoff everywhere on the slope during external wetting data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration soil hydraulic characteristics and antecedent moisture and the slope s hydraulic and geometric characteristics the presented theory predicts the effect an advancing wetting front has on slope stability with respect to translational sliding this paper s theory also develops the 1d pde governing suspended sediment transport and slope degradation caused by runoff influenced by infiltration three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain

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

the effects of fire and water repellency on infiltration and runoff under mediterranean type forest abstract an investigation is being made into the relationship between forest fire and hillslope hydrology in the selva region of catalonia over a three year period at sites with a known fire history the major sites are on granite granodiorite or on sediments derived from these rocks at locations between santa christina d aro and santa coloma de farnes it appears that there is a general relationship between the type of organic profile found in a forest and the impact of fire in terms of loss of organic matter soil erosion hillslope hydrology and on the regeneration of the forest this paper summarises the results of about 150 rainfall simulation experiments and presents an overview of work carried out so far a major conclusion is that runoff processes are discontinuous and spatially structured due mainly to the effects of water repellency as a result of surface properties macropores hydrophobic behaviour and swelling four types of infiltration curve can be recognised at many locations infiltration increases with time during the early part of an experiment reaches a maximum value after about 30 minutes therupon subsequently decreasing this type of relationship can not be modelled with standard infiltration equations illustrations are given of sections through both burnt and unburnt soils to show how the hydrophobic effect influences water penetration it can be seen that infiltration patterns are similar for both burnt and unburnt soils and that micropores filled with organic matter are very important in conducting water through a water repellent surface layer the hydrophobic layer traps water in the bc horizon and prevents evaporation and loss by upwards capillary movement although the hydrophobic effects mean that small areas sometimes have a high runoff coefficient on larger areas there are many macropores and shrubs beneath which the soil is permeable and these trap runoff generated on the water repellent areas the main effect of fire is to illiminate the storage of water in the organic horizons several cm at first infiltration rates remain high but later these decrease as there is a reduction in porosity the sites having a moder type profile have better water retention properties more organic matter that survives the fire and a faster rate of vegetation recovery sites with a mor type profile can be degraded and erode if they are subject to disturbance the study provides another example of how on seemingly uniform slopes hydrological processes are structured by interactions with vegetation the patterns produced by these interactions survive the effects of fire

post disturbance sediment recovery implications for watershed resilience abstract sediment recovery following disturbances is a measure of the time required to attain pre disturbance sediment fluxes insight into the controls on recovery processes and pathways builds understanding of geomorphic resilience we assess post disturbance sediment recovery in three small 1 5 100 km2 largely unaltered watersheds within the northern colorado rocky mountains affected by wildfires floods and debris flows disturbance regimes span 102 floods debris flows to 103 years wildfires for all case studies event sediment recovery followed a nonlinear pattern initial high sediment flux during single precipitation events or high annual snowmelt runoff followed by decreasing sediment fluxes over time disturbance interactions were evaluated after a high severity fire within the south fork cache la poudre basin was followed by an extreme flood one year post fire this compound disturbance hastened suspended sediment recovery to pre fire concentrations 3 years after the fire wildfires over the last 1900 ybp in the south fork basin indicate fire recurrence intervals of 600 years debris flows within the upper colorado river basin over the last two centuries have shifted the baseline of sediment recovery caused by anthropogenic activities that increased debris flow frequency an extreme flood on north st vrain creek with an impounding reservoir resulted in extreme sedimentation that led to a physical state change we introduce an index of resilience as sediment recovery disturbance recurrence interval providing a relative comparison between sites sediment recovery and channel form resilience may be inversely related because of high or low physical complexity in streams we propose management guidelines to enhance geomorphic resilience by promoting natural processes that maintain physical complexity finally sediment connectivity within watersheds is an additional factor to consider when establishing restoration treatment priorities

spatial structures of stream and hillslope drainage networks following gully erosion after wildfire the drainage networks of catchment areas burned by wildfire were analysed at several scales the smallest scale 1 1000 m2 representative of hillslopes and the small scale 1000 m2 to 1 km2 representative of small catchments were characterized by the analysis of field measurements the large scale 1 1000 km2 representative of perennial stream networks was derived from a 30 m digital elevation model and analysed by computer analysis scaling laws used to describe large scale drainage networks could be extrapolated to the small scale but could not describe the smallest scale of drainage structures observed in the hillslope region the hillslope drainage network appears to have a second order effect that reduces the number of order 1 and order 2 streams predicted by the large scale channel structure this network comprises two spatial patterns of rills with width to depth ratios typically less than 10 one pattern is parallel rills draining nearly planar hillslope surfaces and the other pattern is three to six converging rills draining the critical source area uphill from an order 1 channel head the magnitude of this critical area depends on infiltration hillslope roughness and critical shear stress for erosion of sediment all of which can be substantially altered by wildfire order 1 and 2 streams were found to constitute the interface region which is altered by a disturbance like wildfire from subtle unchannelized drainages in unburned catchments to incised drainages these drainages are characterized by gullies also with width to depth ratios typically less than 10 in burned catchments the regions hillslope interface and channel had different drainage network structures to collect and transfer water and sediment copyright 2005 john wiley sons ltd

the clementine mission to the moon scientific overview in the course of 71 days in lunar orbit from 19 february to 3 may 1994 the clementine spacecraft acquired just under two million digital images of the moon at visible and infrared wavelengths these data are enabling the global mapping of the rock types of the lunar crust and the first detailed investigation of the geology of the lunar polar regions and the lunar far side in addition laser ranging measurements provided the first view of the global topographic figure of the moon the topography of many ancient impact basins has been measured and a global map of the thickness of the lunar crust has been derived from the topography and gravity

lunar surface aluminum and iron concentration from galileo solid state imaging data and the mixing of mare and highland materials apollo x ray spectrometer data provide chemical information for 9 of the lunar surface galileo solid state imaging system ssi multispectral data for the moon are employed to reexamine the long accepted positive correlation between lunar surface reflectance or albedo and aluminum concentration derived from apollo x ray spectrometer data the overall goal of the analysis is to quantify the relationship between reflectance and aluminum and to take advantage of the extensive spatial coverage of the ssi data 75 of the lunar surface to calculate aluminum concentration from ssi reflectance for the majority of the lunar surface after removing nonmature highlands from the analysis it is found that the relationship between lunar surface reflectance and x ray spectrometer derived aluminum concentration is described by two diffuse endmembers representing highland and mare materials and an apparent mixing line suggestive of mixtures of mare and highland materials regression analysis is utilized to show that whereas the correlation between reflectance and aluminum for the entire lunar soil system is fairly good the correlations for mare soils alone and for highland soils alone are extremely low the low precision of the x ray data may at least in part be responsible for the observed poor correlations although the low correlation for the individual soil types precludes the precise calculation of aluminum concentration from reflectance approximate aluminum contents can be determined the excellent inverse correlation between aluminum and iron concentration for returned lunar soils allows an estimation of iron content to be made as well an extensive zone of mixtures of mare and highland soils exists in the vicinity of mare filled impact basins and around smaller craters this zone occurs in morphologically defined mare and highland units physical mixing of more mafic and less mafic material due to vertical and lateral transport by impact and downslope movement can account for the widespread mixing zones

fractal techniques and the surface roughness of talus slopes linear plots of log n against log g where n is the number of steps of length g to span a transit are conventionally used as evidence that geomorphic surfaces are self similar fractals i e the surfaces have a constant fractal dimension in this study 42 transits on talus slope surfaces in niagara and letchworth gorges western new york are investigated to ascertain whether they are self similar log n log g plots which r2 values in excess of 0 99 suggest are linear are found upon more rigorous testing to be curvilinear it is concluded that the talus slope surfaces are not self similar and that log n log g plots are relatively insensitive to departures from self similarity the curvilinearity of the log n log g plots is explained with the aid of a randomized square wave model of the talus slope surfaces this model is used to extend the range of measurement beyond that which was possible in the empirical analysis the negative of the gradient of the log n log g relation at a point is the fractal dimension d measurements made upon the randomized square wave model indicate that the relation between d and scale of measurement has an asymmetrical wave shape with a peak i e maximum d where the scale of measurement is equal to the characteristic scale of roughness in other words the value of d for a surface is not absolute but depends on the scale of measurement relative to the scale of roughness linear regression analysis reveals that at the scale of measurement employed in this study d is positively correlated with particle size this is because the values of d fall on the right hand tail of the wave shaped relation between d and scale of measurement transects normal to the direction of slope are found to have higher values of d than profiles parallel to the direction of slope and this is explained in terms of particle orientation shape and juxtaposition because d varies continuously with scale of measurement there are considerable difficulties in using it to characterize and compare the surface roughness of talus slopes generalizing from talus slopes to other ground surfaces it is evident that to the extent that any natural ground surface has a characteristic scale of roughness it will depart from self similarity and d should be used with caution in quantifying the roughness of the surface geomorphologists are therefore urged to be more rigorous in their testing of self similarity before employing d to characterize surface roughness

geologic versus wildfire controls on hillslope processes and debris flow initiation in the green river canyons of dinosaur national monument abstract as in many areas of high relief debris flows are an important process linkage between hillslopes and the green river in the canyons of the eastern uinta mountains yet the physical conditions that lead to debris flow initiation are unknown a recent episode of enhanced debris flow and wildfire activity provided an opportunity to examine the geomorphic impact of fire and the processes by which weathered bedrock is transported to the green river field investigations and analysis of elevation and precipitation data were undertaken in 15 catchments with recent debris flows to determine how surficial geology wildfire topography bedrock strength and meteorology influence hillslope processes the recent debris flows were triggered by intense summer rainstorms the dominant debris flow initiation mechanism the firehose effect occurred when overland flow generated on bedrock hillslopes cascaded down steep cliffs onto colluvium causing failure sixty percent of the debris flows occurred in unburned catchments however 15 of the burned catchments in the study area produced debris flows over the study period whereas only 7 of the unburned catchments did thus fire was not the primary driver of debris flows but fire related events did contribute to the increased debris flow activity the geomorphic impact of wildfire in the eastern uinta mountains is not as great as in transport limited settings with regolith mantled hillslopes the strong rocks and dry climate of the study area cause hillslopes to be very steep and weathering limited with high runoff ratios and a dearth of regolith as a result there is little vegetation and thus we hypothesize that burning does little to change hillslope processes the suite of hillslope processes in the eastern uintas are like those documented in the similarly dry grand canyon but differ from other locations in the western u s where wildfire is a primary control on debris flow processes

illuminating wildfire erosion and deposition patterns with repeat terrestrial lidar erosion following a wildfire is much greater than background erosion in forests because of wildfire induced changes to soil erodibility and water infiltration while many previous studies have documented post wildfire erosion with point and small plot scale measurements the spatial distribution of post fire erosion patterns at the watershed scale remains largely unexplored in this study lidar surveys were collected periodically in a small first order drainage basin over a period of 2 years following a wildfire the study site was relatively steep with slopes ranging from 17 to 30 during the study period several different types of rain storms occurred on the site including low intensity frontal storms 2 4 mm h 1 and high intensity convective thunderstorms 79 mm h 1 these storms were the dominant drivers of erosion erosion resulting from dry ravel and debris flows was notably absent at the site successive lidar surveys were subtracted from one another to obtain digital maps of topographic change between surveys the results show an evolution in geomorphic response such that the erosional response after rain storms was strongly influenced by the previous erosional events and pre fire site morphology hillslope and channel roughness increased over time and the watershed armored as coarse cobbles and boulders were exposed the erosional response was spatially nonuniform shallow erosion from hillslopes 87 of the study area contributed 3 times more sediment volume than erosion from convergent areas 13 of the study area however the total normalized erosion depth volume area was highest in convergent areas from a detailed understanding of the spatial locations of erosion we made inferences regarding the processes driving erosion it appears that hillslope erosion is controlled by rain splash for detachment and overland flow for transport and quasi channelized erosion with the sites of highest erosion corresponding to locations with the lowest roughness by contrast in convergent areas we found erosion caused by overland flow soil erosion was locally interrupted by immobile objects such as boulders bedrock or tree trunks resulting in a patchy erosion network with increasing roughness over time

a revised algorithm for calculating tio2 from clementine uvvis data a synthesis of rock soil and remotely sensed tio2 concentrations 1 investigating mare basalt compositions at both the sample and remote sensing level for the apollo and luna mare sites reveals the need for a more complex regression procedure than previously proposed in order to extract accurate tio2 concentrations from clementine spectral reflectance csr data the tio2 algorithm of lucey and coworkers is modified by using two different sets of regression parameters to relate measured regolith compositions from sampling locations to the csr properties of these sites one regression trend fits the majority of apollo data and the second regression is a fit to the apollo 11 luna 16 and luna 24 data which were considered to be anomalous in previous tio2 calibrations these three sites have unusually low albedo compared to other mare landing sites and some 32 of nearside mare regions appear to share this characteristic possible reasons for these differences related to proximity of the other sites to mare highland boundaries are discussed using the dual regression method we find 1 that tio2 concentrations calculated for the basaltic landing sites faithfully reproduce a bimodal distribution as seen in the sample data 2 that when coupled with the effects of other thermal neutron absorbers ti concentrations are more consistent with observed epithermal to thermal neutron flux ratios than are previous clementine based derivations of tio2 for basaltic regions and 3 that basalts of intermediate tio2 concentrations occur most frequently in the oceanus procellarum region and that these intermediate concentrations appear to be inherent to the flows underlying the regolith and presumably to the basalt source regions

impact of local sea surface temperature anomaly over the western north pacific on extreme east asian summer monsoon in this study the anomalous characteristics of observed large scale synoptic fields in the extreme east asian summer monsoon easm years are analyzed and the impact of the local sea surface temperature sst anomaly over the western north pacific wnp on the extreme easm is investigated through sensitivity experiments of 28 years easm simulations to the local sst over the wnp the observation analysis reveals that the extreme easm is influenced more by anomalous large scale atmospheric features such as monsoon circulations and the western north pacific subtropical high than the local sst anomaly over the wnp however the results of the sensitivity experiments show that the local sst anomaly has an implicit impact on the extreme easm the patterns of differences in precipitation between the experiment forced by observed sst in each year and the experiment forced by climatological sst over the wnp are opposite to anomaly patterns of observed precipitation in the extreme easm years this is because the sst anomaly over the wnp plays a role in reducing precipitation anomaly by changing surface latent heat flux and monsoon circulations in particular the local sst anomaly over the wnp decreases anomalies of large scale circulations i e the local hadley and the walker circulations thus the local sst anomaly over the wnp plays a role in decreasing the interannual variability of the easm

revised mineral and mg maps of the moon from integrating results from the lunar prospector neutron and gamma ray spectrometers with clementine spectroscopy mineralogical measurements from spectral remote sensing and remote geochemical measurements from gamma ray and neutron spectrometers are complementary data sets that have been used together successfully to study the distributions of iron titanium and rare earth elements on the moon we compare neutron and gamma ray data sets from lunar prospector and find them in good agreement with each other within the errors of previously developed equations that relate neutron flux with geochemistry but find small adjustments to the nominal values are warranted we used the neutron validated lp grs oxides to improve clementine based global mineral maps the comparison was enabled by converting the minerals of lucey 2004 to oxides using stoichiometry and assumptions about mg calcium content of clinopyroxenes and an we find that feo and al 2 o 3 derived from the maps of lucey 2004 do not follow the expected negative correlation seen in lunar samples but can be brought into agreement with samples and with lp grs oxides by increasing plagioclase in proportion with orthopyroxene abundance while simultaneously decreasing mg we interpreted this to mean that plagioclase and orthopyroxene exist in rocks together as in a noritic rock with the spectrally difficult to detect plagioclase being masked by the strong spectral signature of the orthopyroxene we generated a revised set of maps of the major lunar minerals and a map of mg for the mafic minerals that are consistent with lunar prospector neutron and gamma ray spectrometer results and show greatly improved agreement with lunar soil samples over previous global mineral maps from clementine

determining the mean depth of overland flow in field studies of flow hydraulics in field studies of interrill overland flow conducted on runoff plots the mean depth of flow is usually obtained by averaging measurements of flow depth at regularly spaced points across the plot including points where there is no flow although this procedure may be appropriate in studies aimed at runoff prediction it is not in studies concerned with flow hydraulics in the latter studies more realistic results can be obtained by excluding those points where the depth is zero and reducing the width of flow in proportion to the number of points excluded failure to do this results in the underestimation of the actual mean flow depth reynolds number and friction factor where discharges are small or microtopography is large this underestimation is likely to be significant

interannual and interdecadal variations of the east asian summer monsoon and tropical pacific ssts part i roles of the subtropical ridge the interannual relationship between the east asian summer monsoon and the tropical pacific ssts is studied using rainfall data in the yangtze river valley and the ncep reanalysis for 1951 96 the datasets are also partitioned into two periods 1951 77 and 1978 96 to study the interdecadal variations of this relationship a wet summer monsoon is preceded by a warm equatorial eastern pacific in the previous winter and followed by a cold equatorial eastern pacific in the following fall this relationship involves primarily the rainfall during the pre mei yu mei yu season may june but not the post mei yu season july august in a wet monsoon year the western north pacific subtropical ridge is stronger as a result of positive feedback that involves the anomalous hadley and walker circulations an atmospheric rossby wave response to the western pacific complementary cooling and the evaporation wind feedback this ridge extends farther to the west from the previous winter to the following fall resulting in an 850 hpa anomalous anticyclone near the southeast coast of china this anticyclone 1 blocks the pre mei yu and mei yu fronts from moving southward thereby extending the time that the fronts produce stationary rainfall 2 enhances the pressure gradient to its northwest resulting in a more intense front and 3 induces anomalous warming of the south china sea surface through increased downwelling which leads to a higher moisture supply to the rain area a positive feedback from the strong monsoon rainfall also appears to occur leading to an intensified anomalous anticyclone near the monsoon region this sst subtropical ridge monsoon rainfall relationship is observed in both the interannual timescale within each interdecadal period and in the interdecadal scale the sst anomalies sstas change sign in northern spring and resemble a tropospheric biennial oscillation tbo pattern during the first interdecadal period 1951 77 in the second interdecadal period 1978 96 the sign change occurs in northern fall and the tbo pattern in the equatorial eastern pacific sst is replaced by longer timescales this interdecadal variation of the monsoon sst relationship results from the interdecadal change of the background state of the coupled ocean atmosphere system this difference gives rise to the different degrees of importance of the feedback from the anomalous circulations near the monsoon region to the equatorial eastern pacific in a wet monsoon year the anomalous easterly winds south of the monsoon enhanced anomalous anticyclone start to propagate slowly eastward toward the eastern pacific in may and june apparently as a result of an atmosphere ocean coupled wave motion these anomalous easterlies carry with them a cooling effect on the ocean surface in 1951 77 this effect is insignificant as the equatorial eastern pacific sstas already change from warm to cold in northern spring probably as a result of negative feedback processes discussed in enso mechanisms in 1978 96 the equatorial eastern pacific has a warmer mean sst a stronger positive feedback between ssta and the walker circulation during a warm phase tends to keep the ssta warm until northern fall when the eastward propagating anomalous easterly winds reach the eastern pacific and reverse the ssta

scale effects on the estimation of erosion thresholds through a distributed and physically based hydrological model abstract slope incision and subsequent development of rills gullies and channels are responsible for significant soil losses and are often irreversible with very high restoration costs particularly in semiarid environments the location of potential areas of erosion where these processes occur is vital to land management and conservation the study of the relationship between the local slope s and the drainage area a through the geomorphological relationship s a b combined with hydrologic simulation models has proved to be appropriate for the identification and characterisation of potential areas of incision especially when it takes into account the spatial distribution of soil properties and the evolution of hydrological processes however physical properties of soil digital elevation models dems and flow algorithms used may affect the results this study employs a distributed physically based hydrological model to evaluate the infiltration runoff relationships and their influence on selecting critical area from three dems with different resolutions the results show a significant scale effect on flow distribution and the location of threshold points on slopes the results obtained from a 30 m dem significantly differ from those obtained from 10 and 5 m dems because the former was unable to capture the spatial variability of geomorphic processes the selected set of critical points shows high s a correlations for different values of critical shear stress the physical model confirmed the dominance of surface runoff in the study site and was validated from field identification of erosion risk areas although for incision areas

small scale density variations in the lunar crust revealed by grail abstract data from the gravity recovery and interior laboratory grail mission have revealed that 98 of the power of the gravity signal of the moon at high spherical harmonic degrees correlates with the topography the remaining 2 of the signal which cannot be explained by topography contains information about density variations within the crust these high degree bouguer gravity anomalies are likely caused by small scale 10 s of km shallow density variations here we use gravity inversions to model the small scale three dimensional variations in the density of the lunar crust inversion results from three non descript areas yield shallow density variations in the range of 100 200 kg m 3 three end member scenarios of variations in porosity intrusions into the crust and variations in bulk crustal composition were tested as possible sources of the density variations we find that the density anomalies can be caused entirely by changes in porosity characteristics of density anomalies in the south pole aitken basin also support porosity as a primary source of these variations mafic intrusions into the crust could explain many but not all of the anomalies additionally variations in crustal composition revealed by spectral data could only explain a small fraction of the density anomalies nevertheless all three sources of density variations likely contribute collectively results from this study of grail gravity data combined with other studies of remote sensing data and lunar samples show that the lunar crust exhibits variations in density by 10 over scales ranging from centimeters to 100 s of kilometers

comparison of soil infiltration rates in burned and unburned mountainous watersheds steady state infiltration measurements were made at mountainous sites in new mexico and colorado usa with volcanic and granitic soils after wildfires and at comparable unburned sites we measured infiltration in the new mexico volcanic soils under two vegetation types ponderosa pine and mixed conifer and in the colorado granitic soils under ponderosa pine vegetation these measurements were made within high severity burn areas using a portable infiltrometer with a 0 017 m 2 infiltration area and artificial rainfall rates ranging from 97 to 440 mm h 1 steadystate infiltration rates were less at all burned sites relative to unburned sites the volcanic soil with ponderosa pine vegetation showed the greatest difference in infiltration rates with a ratio of steady state infiltration rate in burned sites to unburned soils equal to 0 15 volcanic soils with mixed conifer vegetation had a ratio burned to unburned soils of at most 0 38 and granitic soils with ponderosa pine vegetation had a ratio of 0 38 steady state infiltration rates on unburned volcanic and granitic soils with ponderosa pine vegetation are not statistically different we present data on the particle size distribution at all the study sites and examples of wetting patterns produced during the infiltration experiments published in 2001 by john wiley sons ltd

dimensionless erosion laws for cohesive sediment abstracta method of achieving a dimensionless collapse of erosion rate data for cohesive sediments is proposed and shown to work well for data collected in flume erosion tests on mixtures of sand and mud silt plus clay sized particles for a wide range of mud fraction the data collapse corresponds to a dimensional erosion law of the form e c m where e is erosion rate is shear stress c is the threshold shear stress for erosion to occur and m 7 4 this result contrasts with the commonly assumed linear erosion law e kd c where kd is a measure of how easily sediment is eroded the data collapse prompts a re examination of the way that results of the hole erosion test het and jet erosion test jet are customarily analyzed and also calls into question the meaningfulness not only of proposed empirical relationships between kd and c but also of the erodibility parameter kd itself fuller comparison of flume erosion data with hole erosion and jet erosion data will require revised analyses o

gravity field of the orientale basin from the gravity recovery and interior laboratory mission the orientale basin is the youngest and best preserved major impact structure on the moon we used the gravity recovery and interior laboratory grail spacecraft to investigate the gravitational field of orientale at 3 to 5 kilometer km horizontal resolution a volume of at least 3 4 0 2 106 km3 of crustal material was removed and redistributed during basin formation there is no preserved evidence of the transient crater that would reveal the basin s maximum volume but its diameter may now be inferred to be between 320 and 460 km the gravity field resolves distinctive structures of orientale s three rings and suggests the presence of faults associated with the outer two that penetrate to the mantle the crustal structure of orientale provides constraints on the formation of multiring basins

a morphometric analysis of gullies scoured by post fire progressively bulked debris flows in southwest montana usa in the fall of 2001 an intense thunderstorm in southwest montana triggered many debris flows in the burned area of sleeping child creek in most instances the debris flows cut deep gullies into previously unchannelized colluvial hollows and deposited large volumes of sediment onto the valley floor the presence of rill networks above the gullies as well as the absence of landslide features indicate that the gullies were scoured by progressively bulked debris flows a process in which dilute surface runoff becomes increasingly more laden with sediment until it transforms into a debris flow in this contribution we present a morphometric analysis of six of the gullies to better understand this relatively understudied process we find that the locations of the rill heads and gully heads conform to slope area thresholds that are characteristic of erosion by overland flow our data also suggest that the volumes of the debris flows increase exponentially with normalized drainage area thus lending support to an assumption used in a recently proposed debris flow incision law finally the debris flow fans have been relatively unaltered since deposition suggesting that the valley may be currently aggrading while the hillslopes are being denuded

effects of vegetation disturbance by fire on channel initiation thresholds abstract the disturbance or removal of vegetation by wildfire influences channel incision following intense rainfall events here we empirically examine relationships between the severity of vegetation disturbance and geomorphic controls on threshold conditions that lead to channel incision we conducted post fire field mapping and digital spatial analyses across 97 recently formed channel heads in the rocky mountains of montana and idaho usa to identify the relationship between remotely sensed fire severity and vegetation disturbance and the source area and gradient conditions required for channel initiation we found that the relationship between the size of source areas and source area steepness was described by an inverse power function consistent with established theory across the range of fire severity but that the magnitude of the slope area relationship was significantly correlated with increasing fire severity further at higher levels of fire severity source areas above channel heads had lower slopes and somewhat larger areas the findings suggest that the onset of channel incision defined by location of channel heads is controlled by fire severity and that the threshold for channel initiation decreases as vegetation disturbance increases we also found that in a subset of catchments for which lidar data were available total curvature explained channel head location across the range of fire severity with a small but significant contribution from source area steepness steepness remains more important at lower fire severity however and total curvature dominates where fire severity is most extreme this suggests that forces of convergent flow are not fully expressed until a significant proportion of vegetation has been consumed such that flow resistance is minimized our findings and the use of a continuous fire severity metric contribute an ecohydrological and biogeomorphical template for studies of post fire geomorphic responses and landscape evolution

chemical information content of lunar thermal and epithermal neutrons simulations of equilibrium thermal and epithermal neutron flux spectra for the moon have been studied to determine their chemical information content most of this information resides in a single parameter the ratio of macroscopic absorption to energy loss cross sections although this parameter cannot specify the chemistry of lunar soils uniquely it provides an index that can be used to quantitatively separate anorthositic from mafic chemistries hydrogen abundances can best be derived from measurements of the epithermal neutron flux which is strongly related to its macroscopic energy loss cross section the ratio of thermal to epithermal neutron flux measured by lunar prospector is shown to agree quantitatively with simulations this agreement is used to show that the highlands terrane on the farside of the moon is anorthositic containing high percentages of plagioclase and possibly a range of mg suite minerals with a high mg mg fe atomic ratio our best estimate of the abundance of feo is 2 with an upper limit of 5

the effects of wildfire on the sediment yield of a coastal california watershed the occurrence of two wildfi res separated by 31 yr in the chaparral dominated arroyo seco watershed 293 km 2 of california provides a unique opportunity to evaluate the effects of wildfi re on suspended sediment yield here we compile discharge and suspended sediment sampling data from before and after the fi res and show that the effects of the postfi re responses differed markedly the 1977 marble cone wildfi re was followed by an exceptionally wet winter which resulted in concentrations and fl uxes of both fi ne and coarse suspended sediment that were 35 times greater than average sediment yield during the 1978 water year was 11 000 t km 2 yr we suggest that the combined 1977 1978 fi re and fl ood had a recurrence interval of greater than 1000 yr in contrast the 2008 basin complex wildfi re was followed by a drier than normal year and although suspended sediment fl uxes and concentrations were signifi cantly elevated compared to those expected for unburned conditions the sediment yield during the 2009 water year was less than 1 of the post marble cone wildfi re yield after the fi rst postfi re winters sediment concentrations and yield decreased with time toward prefi re relationships and continued to have signifi cant rainfall dependence we hypothesize that the differences in sediment yield were related to precipitationenhanced hillslope erosion processes such as rilling and mass movements the millennialscale effects of wildfi re on sediment yield were explored further using monte carlo simulations and these analyses suggest that infrequent wildfi res followed by flincrease long term suspended sediment fl markedly thus we suggest that the current approach of estimating sediment yield from sediment rating curves and discharge data without including periodic perturbations from wildfi res may grossly underestimate actual sediment yields

x ray digital imaging petrography of lunar mare soils modal analyses of minerals and glasses it is essential that accurate modal i e volume percentages of the various mineral and glass phases in lunar soils be used for addressing and resolving the effects of space weathering upon reflectance spectra as well as for their calibration such data are also required for evaluating the resource potential of lunar minerals for use at a lunar base however these data are largely lacking particle counting information for lunar soils originally obtained to study formational processes does not provide these necessary data including the percentages of minerals locked in multi phase lithic fragments and fused soil particles such as agglutinates we have developed a technique for modal analyses sensu stricto of lunar soils using digital imaging of x ray maps obtained with an energy dispersive spectrometer mounted on an electron microprobe a suite of nine soils 90 to 150 micrometers size fraction from the apollo 11 12 15 and 17 mare sites was used for this study this is the first collection of such modal data on soils from all apollo mare sites the abundances of free mineral fragments in the mare soils are greater for immature and submature soils than for mature soils largely because of the formation of agglutinitic glass as maturity progresses in considerations of resource utilization at a lunar base the best lunar soils to use for mineral beneficiation i e most free mineral fragments have maturities near the immature submature boundary is feo approximately or 30 not the mature soils with their complications due to extensive agglutination the particle data obtained from the nine mare soils confirm the generalizations for lunar soils predicted by l a taylor and d s mckay 1992 lunar planet sci conf 23rd pp 1411 1412 abstract

the long term topographic response of a continent adjacent to a hyperextended margin a case study from scandinavia we present data that link scandinavia s passive margin domains under a unified system invoking isostatically driven postextension phase vertical adjustments to severe crustal thinning topographic and geological data indicate that the relative location of the first landward occurrence of total crustal embrittlement or deformation coupling the taper break controlled and continues to control scandinavia s post thinning geomorphic evolution formed during late jurassic or early cretaceous thinning yet marked today by seismicity the taper break closely approximates the boundary between 1 less stretched lithosphere that increases in rigidity both toward land and through postrift time and 2 the highly attenuated pervasively faulted permanently weakened lithosphere of the distal margin following the stretching thinning and exhumation phases proposed by other workers an accommodation phase is warranted commencing during sag basin time and continuing today it is probably driven by thermal cooling and mass transfer from the escarpment to the basins offshore the accommodation phase does not entirely coincide with the traditional postrift phase as the former may contain the latter during accommodation the original synrift escarpments can be eroded to very low base levels sharply tapered margin segments can undergo subsequent rejuvenation by out of sequence normal faulting and footwall uplift probably in response to tensile bending stresses engendered by lithospheric scale flexure accommodation phase uplift at passive margins is the inexorable and penultimate phase of hyperextension and may perhaps be followed by the onset of subduction localized by the weakened lithosphere of the distal margin and the ocean continent transition

sediment availability on burned hillslopes 1 erodibility describes the inherent resistance of soil to erosion hillslope erosion models typically consider erodibility to be constant with depth this may not be the case after wildfire because erodibility is partly determined by the availability of noncohesive soil and ash at the surface this study quantifies erodibility of burned soils using methods that explicitly capture variations in soil properties with depth flume experiments on intact cores from three sites in western united states showed that erodibility of fire affected soil was highest at the soil surface and declined exponentially within the top 20 mm of the soil profile with root density and soil depth accounting for 62 of the variation variation in erodibility with depth resulted in transient sediment flux during erosion experiments on bounded field plots material that contributed to transient flux was conceptualized as a layer of noncohesive material of variable depth dnc this depth was related to shear strength measurements and sampled spatially to obtain the probability distribution of noncohesive material as a function of depth below the surface after wildfire in southeast australia the initial dnc ranged from 7 5 to 9 1 mm which equated to 97 117 mg ha 1 of noncohesive material the depth decreased exponentially with time since wildfire to 0 4 mm or 5 mg ha 1 after 3 years of recovery the results are organized into a framework for modeling fire effects on erodibility as a function of the production and depletion of the noncohesive layer overlying a cohesive layer

initiation of motion in overland flow this article reports the results of an experimental study concerning the initial movement of sediment in overland flow experiments were carried out in a small flume using water and quartz materials of various grain sizes the comparison of our experimental results with classic criteria showed that the shields curve and the criterion of yang can also be used for turbulent overland flow generally higher shear stresses are necessary to provoke bed instability under laminar flow conditions especially at higher shear velocity particle reynolds numbers a relative roughness effect also exists in laminar flow contrary to the observations by savat on fixed beds laminar flow does not show an uncommon selectivity when loose homogeneous beds are considered

critical shear stress for erosion of cohesive soils subjected to temperatures typical of wildfires received 26 february 2004 revised 15 september 2004 accepted 5 november 2004 published 22 january 2005 1 increased erosion is a well known response after wildfire to predict and to model erosion on a landscape scale requires knowledge of the critical shear stress for the initiation of motion of soil particles as this soil property is temperature dependent a quantitative relation between critical shear stress and the temperatures to which the soils have been subjected during a wildfire is required in this study the critical shear stress was measured in a recirculating flume using samples of forest soil exposed to different temperatures 40 550 c for 1 hour results were obtained for four replicates of soils derived from three different types of parent material granitic bedrock sandstone and volcanic tuffs in general the relation between critical shear stress and temperature can be separated into three different temperature ranges 275 c which are similar to those for water repellency and temperature the critical shear stress was most variable 1 0 2 0 n m 2 for temperatures 2 0 n m 2 between 175 and 275 c and was essentially constant 0 5 0 8 n m 2 f or temperatures 275 c the changes in critical shear stress with temperature were found to be essentially independent of soil type and suggest that erosion processes in burned watersheds can be modeled more simply than erosion processes in unburned watersheds wildfire reduces the spatial variability of soil erodibility associated with unburned watersheds by eliminating the complex effects of vegetation in protecting soils and by reducing the range of cohesion associated with different types of unburned soils our results indicate that modeling the erosional response after a wildfire depends primarily on determining the spatial distribution of the maximum soil temperatures that were reached during the wildfire

moon near infrared spectral reflectance a first good look a positive identification of the minerals olivine plagioclase and several types of pyroxenes were made at several locations on the lunar surface by using remote measurements for example the crater aristarchus is found to have an average pyroxene composition of augite and plagioclase is obviously present a dark mantle deposit in the crater j herschel is at least partly composed of a mixture of 70o7o olivine and 30o7o pyroxene these determinations were possible because the reflectance spectra for 10 20 km diameter lunar areas have been measured for the first time in the ir spectral region 0 65 2 5 m with sufficient spectral resolution and photometric precision to define mineral electronic absorption bands the reflectance for all lunar regions observed over 100 to present continues to increase toward longer wavelengths to at least 2 5 m and several mineral absorption bands appear the telescopic spectra are of similar quality and contain features similar to laboratory spectra of lunar samples the absorption features in several spectra have been quantitatively analyzed using newly developed computer processing techniques including thermal flux removal and absorption band fitting to produce these mineral identifications detection and quantitative analysis of these absorptions provide a much improved basis for remotely determining and mapping surface mineralogy quantitatively from the ground or using airborne or spacecraft platforms

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

pacific east asian teleconnection how does enso affect east asian climate observational evidence is presented to show a teleconnection between the central pacific and east asia during the extreme phases of enso cycles this pacific east asian teleconnection is confined to the lower troposphere the key system that bridges the warm cold events in the eastern pacific and the weak strong east asian winter monsoons is an anomalous lower tropospheric anticyclone cyclone located in the western north pacific the western north pacific wind anomalies develop rapidly in late fall of the year when a strong warm or cold event matures the anomalies persist until the following spring or early summer causing anomalously wet dry conditions along the east asian polar front stretching from southern china northeastward to the east of japan kuroshio extension using atmospheric general circulation and intermediate models the authors show that the anomalous philippine sea anticyclone results from a rossby wave response to suppressed convective heating which is induced by both the in situ ocean surface cooling and the subsidence forced remotely by the central pacific warming the development of the anticyclone is nearly concurrent with the enhancement of the local sea surface cooling both the anticyclone and the cooling region propagate slowly eastward the development and persistence of the teleconnection is primarily attributed to a positive thermodynamic feedback between the anticyclone and the sea surface cooling in the presence of mean northeasterly trades the rapid establishment of the philippine sea wind and sst anomalies implies the occurrence of extratropical tropical interactions through cold surge induced exchanges of surface buoyancy flux the central pacific warming plays an essential role in the development of the western pacific cooling and the wind anomalies by setting up a favorable environment for the anticyclone sst interaction and midlatitude tropical interaction in the western north pacific

the evolution of a colluvial hollow to a fluvial channel with periodic steps following two transformational disturbances a wildfire and a historic flood abstract the transition of a colluvial hollow to a fluvial channel with discrete steps was observed after two landscape scale disturbances the first disturbance a high severity wildfire changed the catchment hydrology to favor overland flow which incised a colluvial hollow creating a channel in the same location this incised channel became armored with cobbles and boulders following repeated post wildfire overland flow events three years after the fire a record rainstorm produced regional flooding and generated sufficient fluvial erosion and sorting to produce a fluvial channel with periodically spaced steps an analysis of the step spacing shows that after the flood newly formed steps retained a similar spacing to the topographic roughness spacing in the original colluvial hollow prior to channelization this suggests that despite a distinct change in channel form roughness and bedform morphology the endogenous roughness periodicity was conserved variations in sediment erodibility helped to create the emergent steps as the largest particles d84 remained immobile becoming step features and downstream soil was easily winnowed away

sediment and hydrological response to vegetation recovery following wildfire on hillslopes and the hollow of a small watershed summary wildfire can cause dynamically spatial and temporal variations of hydrology and sedimentation from forested environments the largest wildfire historically recorded in south korea burned 23 484 ha of forest land in april 2000 in 2001 systems to monitor post fire runoff and sediment were installed at the outlet of a small watershed and at seven plots on hillslopes of different vegetation condition the hillslope and catchment responses were monitored for five years post fire the watershed was divided into four sites including terrace sodding ts pine planting and fast recovery pf pine planting and slow recovery ps and hollow h according to treatment methods and topographical characteristic the ts site showed the fastest vegetation recovery among the sites and the greatest reduction of soil erosion with time elapsed after wildfire sediment yield from the watershed as well as from plots depended strongly on rainfall erosivity index while the runoff coefficient showed the highest correlation with rainfall amount the sediment response rate had the strongest correlation with a vegetation index characterizing vegetation structure litter and root the hollow mostly acted as a depositional zone but only contributed to erosion when it was disturbed by the treatment applications following the fire or during heavy rain following landslide activity in the catchment these results indicate that gently sloping hollow areas with rapidly recovering vegetation have the potential to reduce the flood and sediment risk however heavy and extreme rainfall events during the study produced excessive sediment by catastrophic debris flow and landslide processes even on vegetated hillslopes the study suggests that the boundary condition for whether i rain is heavy or extreme ii surface condition is bare and iii terrain has a deposition zone should be considered in order to evaluate sediment yields from burnt catchments

geochemistry of the lunar highlands as revealed by measurements of thermal neutrons thermal neutron emissions from the lunar surface provide a direct measure of bulk elemental composition that can be used to constrain the chemical properties of near surface depth 85 are generally associated with large impact basins and are colocated with clusters of nearly pure plagioclase identified with spectral reflectance data

lunar rare earth element distribution and ramifications for feo and tio2 lunar prospector neutron spectrometer observations lunar prospector neutron spectrometer data have been used to map the global surface distribution of the incompatible rare earth elements gadolinium and samarium from the low altitude 30 15 km mapping orbit these results afford improved surface resolution and detailed views of the potassium rare earth elements and phosphorus kreep distribution within and around mare imbrium and elsewhere the gd and sm results serve as a complementary and independent check of the distribution of kreep on the moon in contrast with the lunar prospector gamma ray spectrometer results for thorium the neutron spectrometer observations reflect the presence of fe and ti as well as gd and sm the contributions of fe and ti are removed using high spatial resolution clementine spectral reflectance determinations of feo and tio2 abundances overall the resulting gd and sm abundance map agrees with the th abundance map determined using the lunar prospector gamma ray spectrometer in general the detailed features of the procellarum imbrium kreep terrane are found in both for example distinct highs in gd sm and th abundances are resolved over the craters mairan aristarchus kepler reinhold lalande and aristillus over the apennine bench and fra mauro regions and over the montes jura and montes carpatus indicating an enhanced abundance of kreep in these locations the neutron observations also provide constraints on feo and tio2 abundances for some high ti locales there is a significant disagreement with tio2 abundances inferred from clementine spectral reflectance

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

hydraulics and erosion in eroding rills rills often act as sediment sources and the dominant sediment and water transport mechanism for hillslopes six experiments were conducted on two soils and a uniform sand using three experimental methodologies the results of this study challenge the assumption often used in hydrologic and erosion models that relationships derived for sheet flow or larger channel flow are applicable to actively eroding rills velocity did not vary with slope and reynolds number was not a consistent predictor of hydraulic friction this result was due to interactions of slope gradient flow rate erosion and the formation of rill roughness bed structures and head cuts a relationship for rill flow velocities was proposed stream power was found to be a consistent and appropriate predictor for unit sediment load for the entire data set while other hydraulic variables were not the data for stream power and sediment load fit the form of a logistic curve r2 0 93 which is promising relative to recently proposed erosion models which are based on probabilistic particle threshold theory

iron abundances on the lunar surface as measured by the lunar prospector gamma ray and neutron spectrometers i global measurements of iron abundances on the lunar surface are presented using data from the lunar prospector lp gamma ray spectrometer grs and neutron spectrometer ns in this study we derive relative iron abundances from the low altitude high spatial resolution 45 km 2 lp data using the 7 6 mev neutron capture gamma ray doublet as part of the lp grs analysis we demonstrate the importance of accounting for variations in neutron number density across the lunar surface by measuring neutron fluxes using lp ns data in a first step of comparing the lp grs data with previously published iron abundances inferred from clementine spectral reflectance csr data we show that the existing csr feo data are nonlinear with respect to the lp relative iron abundances we use the lp data to linearize the relationship between the csr and the relative iron values then recalibrate the csr data to iron abundance using returned soil abundances we then correlate the csr data except for major anomalies with the lp relative iron measurements to convert the lp data to absolute iron abundances when we compare the lp grs and revised csr data sets we find a very good correspondence there are two locations mare tranquillitatis and south pole aitken spa basin that show major discrepancies suggesting that the csr data are locally overestimating iron abundances in both these regions the discrepancies identified by the lp grs csr comparison are possibly explained by mineralogical differences that are not accounted for in the csr to feo calibration in regards to our understanding of the moon the lp data have found the following i there exist large expanses of mare basalt in the western mare regions that have very high iron abundances 22 23 wt feo that are underrepresented but not absent from the returned sample collection and are highly unusual for mare soils which typically contain a significant amount of highlands contamination 2 the low iron abundances in the lunar highlands 5 feo wt are consistent with a previous analysis using thermal and epithermal neutrons and with the idea that the lunar crust formed by a relatively simple magma ocean process 3 the comparison of lp and csr derived iron abundances suggests that the material within spa basin is similar to a norite type rock without an enriched mantle feo signature 4 a comparison of lp and csr data at tycho crater shows a large discrepancy such that the csr data show moderate iron abundances of 8 9 wt feo while the lp data show very low iron abundances of 3 4 wt feo this discrepancy cannot yet be easily explained by any known process

the effects of space weathering on apollo 17 mare soils petrographie and chemical characterization the lunar soil characterization consortium a group of lunar sample and remote sensing scientists has undertaken the extensive task of characterization of the finest fractions of lunar soils with respect to their mineralogical and chemical makeup these compositional data form the basis for integration and modeling with the reflectance spectra of these same soil fractions this endeavor is aimed at deciphering the effects of space weathering of soils on airless bodies with quantification of the links between remotely sensed reflectance spectra and composition a beneficial byproduct is an understanding of the complexities involved in the formation of lunar soil several significant findings have been documented in the study of the 2x whereas the abundance of agglutinitic glass increases by only 10 15 this is evidence for a large contribution from surface correlated nanophase fe0 to the is feo values particularly in the 10 m size fraction the surface nanophase fe0 is present largely as vapor deposited patinas on the surfaces of almost every particle of the mature soils and to a lesser degree for the immature soils keller et al 1999a it is reasoned that the vapor deposited patinas may have far greater effects upon reflectance spectra of mare soils than the agglutinitic fe0

hydraulics of interrill overland flow on a semi arid hillslope southern arizona parsons a j abrahams a d and luk s h 1990 hydraulics of interrill overland flow on a semi arid hillslope southern arizona j hydrol 117 255 273 simulated rainfall experiments were conducted on an 18 m wide by 35 m long runoff plot located in southern arizona by using a wide plot that extended from the divide to beyond the rill heads it was possible to examine the full range of lateral variability and downslope changes in interrill overland flow on a shrub covered semi arid piedmont hillslope the mean depth d mean velocity v and reynolds number re of overland flow were computed for two measured sections situated 12 5 and 21 m from the top of the plot at a section d vs re and v vs re relations show that increases in re are accomodated largely by increases in d these hydraulic relations are principally the result of resistance to flow increasing with re as overland flow spreads into new areas inasmuch as the maximum equilibrium discharge simulated in these experiments has a return period of about 7 yr increasing resistance to flow as re increases may be considered typical of most overland flow events on shrub covered piedmont hillslopes in southern arizona downslope hydraulic relations differ strikingly from at a section relations under equilibrium runoff conditions resistance to flow decreases rapidly as re increases permitting increases in re to be accomodated entirely by increases in v the decrease in resistance to flow is due to progressive downslope concentration of flow into fewer deeper threads under non equilibrium conditions downslope hydraulic relations may be quite different from those obtaining at equilibrium but resistance to flow always decreases downslope this is the result of low flows following pathways formed by higher flows that concentrate downslope analyses of overland flow hydraulics at the scale of interrill areas produce results that are quite different from those obtained from small plots a knowledge of the hydraulics at this scale is essential if models of interrill overland flow are to become more realistic and hence better predictors of runoff hydrographs and sediment yield

post fire bedload sediment delivery across spatial scales in the interior western united states post fire sediment yields can be up to three orders of magnitude greater than sediment yields in unburned forests much of the research on post fire erosion rates has been at small scales 100 m2 or less and post fire sediment delivery rates across spatial scales have not been quantified in detail we developed relationships for post fire bedload sediment delivery rates for spatial scales up to 117 ha using sediment yield data from six published studies and two recently established study sites sediment yields and sediment delivery ratios sdrs sediment delivered at the catchment scale divided by the sediment delivered from a plot nested within the catchment were related to site factors including rainfall characteristics area length and ground cover unit area sediment yields significantly decreased with increasing area in five of the six sites the annual sdrs ranged from 0 0089 to 1 15 and these were more closely related to the ratio of the plot lengths than the ratio of plot areas the developed statistical relationships will help quantify post fire sediment delivery rates across spatial scales in the interior western united states and develop process based scaling relationships published in 2013 this article is a u s government work and is in the public domain in the usa

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

residence times and alluvial architecture of a sediment superslug in response to different flow regimes abstract a superslug was deposited in a basin in the colorado front range mountains as a consequence of an extreme flood following a wildfire disturbance in 1996 the subsequent evolution of this superslug was measured by repeat topographic surveys 31 surveys from 1996 through 2014 of 18 cross sections approximately uniformly spaced over 1500 m immediately above the basin outlet these surveys allowed the identification within the superslug of chronostratigraphic units deposited and eroded by different geomorphic processes in response to different flow regimes over the time period of the study the superslug went through aggradation incision and stabilization phases that were controlled by a shift in geomorphic processes from generally short duration episodic large magnitude floods that deposited new chronostratigraphic units to long duration processes that eroded units these phases were not contemporaneous at each channel cross section which resulted in a complex response that preserved different chronostratigraphic units at each channel cross section having in general two dominant types of alluvial architecture laminar and fragmented age and transit time distributions for these two alluvial architectures evolved with time since the extreme flood because of the complex shape of the distributions they were best modeled by two parameter weibull functions the weibull scale parameter approximated the median age of the distributions and the weibull shape parameter generally had a linear relation that increased with time since the extreme flood additional results indicated that deposition of new chronostratigraphic units can be represented by a power law frequency distribution and that the erosion of units decreases with depth of burial to a limiting depth these relations can be used to model other situations with different flow regimes where vertical aggradation and incision are dominant processes to predict the residence time of possible contaminated sediment stored in channels or on floodplains and to provide insight into the interpretation of recent or ancient fluvial deposits

erosion thresholds and land surface morphology we propose a graphical technique to analyze the entirety of landforms in a catchment to define quantitatively the spatial variation in the dominance of different erosion processes high resolution digital elevation data of a 1 2 km2 hilly area where the channel network had been mapped in the field were used in the digital terrain model topog to test threshold theories for erosion the land surface was divided into 20 m2 elements whose shapes were then classified as convergent planar or divergent the entire landscape plotted on a graph of area per unit contour length against surface gradient shows each planform plotting as a separate field a simple steady state hydrologic model was used to predict zones of saturation and areas of high pore pressure to mimic the extreme hydrologic events responsible for erosive instability of the land surface the field observation that saturation overland flow is rare outside convergent zones provided a significant constraint on the hydrologic parameter in the model this model was used in threshold theories to predict areas of slope instability and areas subject to erosion by saturation overland flow both of which can contribute to channel initiation the proportion of convergent elements predicted to exceed the threshold varies greatly with relatively small changes in surface resistance demonstrating a high sensitivity to land use such as cattle grazing overall the landscape can be divided using erosion threshold lines into areas prone to channel instability due to runoff and stable areas where diffusive transport predominates

comparison of gully erosion estimates using airborne and ground based lidar on santa cruz island california abstract gully erosion removes comparatively large volumes of soil from small areas it is often difficult to quantify the loss of soil because the footprint of individual gullies is too small to be captured by most generally available digital elevation models dems such as the usgs national elevation dataset airborne lidar light detection and ranging has the potential to provide the required data density but an even newer class of ground based sensors may provide better local resolution at lower cost in this study we compared digital elevation models produced by airborne and ground based lidar systems with ground based geomorphic and geodetic survey data to determine their utility in quantifying volumetric soil loss due to gully erosion in a heavily degraded watershed 7 55 10 2 km 2 on southwestern santa cruz island in southern california volumetric estimates of the eroded sediment were produced by comparing the lidar derived dems of the gully system to a modeled pre erosion surface average point densities were significantly higher for the ground based lidar system and provided more detailed information however its limited scanning footprint and side looking orientation presented serious challenges in collecting continuous data from deeply incised gullies making the airborne system preferable for this type of investigation and likely for most applications where heavy topographic shadowing is prevalent

post wildfire erosion response in two geologic terrains in the western usa abstract volumes of eroded sediment after wildfires vary substantially throughout different geologic terrains across the western united states these volumes are difficult to compare because they represent the response to rainstorms and runoff with different characteristics however by measuring the erosion response as the erodibility efficiency of water to detach and transport sediment on hillslopes and in channels the erosion response from different geologic terrains can be compared specifically the erodibility efficiency is the percentage of the total available stream power expended to detach remobilize or transport a mass of sediment erodibility efficiencies were calculated for the i initial detachment and for the ii remobilization and transport of sediment on the hillslopes and in the channels after wildfire in two different geological terrains the initial detachment efficiencies for the main channel and tributary channel in the granitic terrain were 10 9 and 5 4 and were similar to those for the volcanic terrain which were 5 5 and 1 1 no initial detachment efficiency could be measured for the hillslopes in the granitic terrain because hillslope measurements were started after the first major rainstorm the initial detachment efficiency in the volcanic terrain was 1 3 0 41 the average remobilization and transport efficiencies associated with flash floods in the channels also were similar in the granitic 0 18 0 57 and volcanic 0 11 0 41 terrains on the hillslope the remobilization and transport efficiency was greater in the volcanic terrain 2 4 than in the granitic terrain 0 65 however this may reflect the reduced sediment availability after the first major rainstorm 30 min maximum rainfall intensity 90 mm h 1 in the granitic terrain while easily erodible fine colluvium remained on the hillslope after the first rainstorm 30 min maximum rainfall intensity 7 2 mm h 1 in the volcanic terrain the erosion response in channels and on hillslopes of the granitic and volcanic terrains was similar when compared using erodibility efficiencies

lunar prospector overview lunar prospector is providing a global map of the composition of the moon and analyzing the moon s gravity and magnetic fields it has been in a polar orbit around the moon since 16 january 1998 neutron flux data show that there is abundant h and hence probably abundant water ice in the lunar polar regions gamma ray and neutron data reveal the distribution of fe ti and other major and trace elements on the moon the data delineate the global distributions of a key trace element rich component of lunar materials called kreep and of the major rock types magnetic mapping shows that the lunar magnetic fields are strong antipodal to mare imbrium and mare serenitatis and has discovered the smallest known magnetosphere magnetosheath and bow shock complex in the solar system gravity mapping has delineated seven new gravity anomalies and shown that the moon has a small fe rich core of about 300 km radius

mineral maps of the moon 1 global maps of the distribution of plagioclase orthopyroxene clinopyroxene and olivine on the moon were derived from radiative transfer analysis of 400 000 clementine uvvis spectra plagioclase inversely correlates with iron while clinopyroxene positively correlates with iron showing these are the major carriers of aluminum and iron respectively the distribution of olivine in the maria agrees with previous studies in the highlands the abundance of olivine is low but ubiquitous at a few percent except within the south pole aitken basin where it is only present in very small exposures in the very anorthositic farside highlands olivine is often the sole mafic mineral the abundance of orthopyroxene is generally low excepting elevated abundances in the nearside highlands and in areas near and within south pole aitken basin mare units with elevated abundances of orthopyroxene are found in some mare and cryptomare deposits distant from the sample return sites

lunar iron and titanium abundance algorithms based on final processing of clementine ultraviolet visible images the clementine mission to the moon returned global imaging data collected by the ultraviolet visible uvvis camera this data set is now in a final state of calibration and a five band multispectral digital image model dim of the lunar surface will soon be available to the science community we have used observations of the lunar sample return sites and stations extracted from the final dim in conjunction with compositional information for returned lunar soils to revise our previously published algorithms for the spectral determination of the feo and tio2 content of the lunar surface the algorithms successfully normalize the effects of space weathering so that composition may be determined without regard to a surface s state of maturity these algorithms permit anyone with access to the standard archived dim to construct high spatial resolution maps of feo and tio2 abundance such maps will be of great utility in a variety of lunar geologic studies

dynamical and boundary forcing characteristics of regional components of the asian summer monsoon abstract in this paper the authors present a description of the internal dynamics and boundary forcing characteristics of two major subcomponents of the asian summer monsoon asm that is the south asian monsoon sam and the east southeast asian monsoon eam the description is based on a new monsoon climate paradigm in which the variability of asm is considered as the outcome of the interplay of a fast and an intermediate monsoon subsystem under the influence of slow external forcings two sets of regional monsoon indices derived from dynamically consistent rainfall and wind data are used in this study results show that the internal dynamics of sam are representative of a classical monsoon system in which the anomalous circulation is governed by rossby wave dynamics where anomalous vorticity induced by an off equatorial heat source is balanced by the advection of planetary vorticity on the other hand the internal dynamics of eam are characterized by a hybrid monsoon system featuring m

the mafic component of the lunar crust constraints on the crustal abundance of mantle and intrusive rock and the mineralogy of lunar anorthosites most models of early lunar evolution predict that the anorthositic highlands crust is the result of plagioclase flotation on a magma ocean however the lunar highlands crust typically contains 4 wt feo and so is more mafic than the strict definition of the anorthosites thought to comprise it we used new clementine based mineral maps of the moon as inputs to a series of mixing models that calculate the abundance and distribution of major highland rock types and shed light on three possible sources of excess mafic material in the lunar highlands mafic 15 vol mafic minerals anorthosites post magma ocean igneous activity and mafic basin ejecta mixing models that feature pure anorthosites like the purest anorthosite pan described by ohtake et al 2009 and pieters et al 2009 are most compatible with the data they allow us to place an upper limit of 10 20 vol mantle material that could be mixed with the primary highlands crust the upper limit on mantle material indicated by the mixing models is significantly lower than the 30 40 vol mantle material expected from simple geometric calculations of the major lunar basins excavation cavities based on an excavation cavity depth diameter ratio of 1 10 this discrepancy allows us to conclude that the excavation cavities of the three largest lunar basins may have been significantly shallower than those of the smaller basins our results are consistent with excavation cavity depth diameter ratios for these largest basins in the range of 0 035 to 0 06 which agrees with previous gravity measurements by wieczorek and phillips 1999

functional and structural connectivity within a recently burned drainage basin abstract studies examining post wildfire sediment transport have often focused on changes to individual landscape compartments planar slopes rills gullies channels or alluvial fans or have captured coarse scale hydrologic and sediment transport events at the drainage basin scale we advance the understanding of functional and structural connectivity by quantifying changes of the morphodynamics of and sediment transport along seven rill gully threads rgts after two low intensity rainstorms in a burned basin from the 2008 gap fire near goleta ca usa tls surveys conducted within two months of the initial fire and three days after the rainfall events provide point clouds for high resolution digital terrain models dtms dtm differencing techniques and morphological sediment budgets from the rgts showed discontinuous sediment transport along the extent of these two landscape compartments immediately after the rainfall surface runoff was unable to remove dry ravel deposits within the rgts and implied a high degree of structural disconnectivity there dry ravel and runoff erosion from the contributing areas to the rgts indicated functional and structural connectivity at this scale of analysis the results provide clear evidence that small amounts of rainfall and gravity induced erosion are interacting at different scales within the recently burned watershed to produce structural and functional disconnectivity along the rgts while the current system was transport limited during the analyzed event higher magnitude rainstorms may produce enhanced connectivity resulting in the ability of surface runoff to remove the stored sediments and perhaps produce debris flows

constraining the relative importance of raindrop and flow driven sediment transport mechanisms in postwildfire environments and implications for recovery time scales national geographic society proposal002929 2009 0046 1 national science foundation 02 39749 09 34131 u s geological survey usgs landslide hazards program

a large spectral survey of small lunar craters implications for the composition of the lunar mantle a global spectral survey of 4506 immature craters with diameters 1 km was carried out using near ir data from the kaguya spectral profiler to characterize the composition of the lunar megaregolith on the basis of band minima and radiative transfer mixing models small crater spectra fall into three groups 1 mare basalts with strong absorptions at relatively long wavelengths indicating high ratios of high to low ca pyroxene 2 norites containing about 50 plagioclase and with pyroxene assemblages dominated by low ca pyroxene that occur within the south pole aitken basin spa near apollo 14 and other locations near imbrium basin and three major cryptomaria deposits and 3 noritic anorthosites occurring within the feldspathic highlands terrane containing about 20 wt pyroxene with a pyroxene assemblage containing exclusively very low ca pyroxene very few pure anorthosites are present in this survey and there are no occurrences of pyroxene poor olivine rich assemblages models of the composition of basin ejecta incorporate large amounts of mantle material and the spectral results require that that the sampled mantle is orthopyroxenite basin depth diameter ratios used in the models required to match the measured composition are consistent with prior estimates for the largest basins the composition found in the spa and imbrium regions are consistent with mafic impact melt breccias or basaltic impact melts of basin origin for spa we model this composition and find it requires an extremely low impact angle while this is consistent with prior work on an oblique impact for the spa event a more robust solution invokes the production of norite in impact melt seas

post fire hillslope debris flows evidence of a distinct erosion process abstract after wildfire a hitherto unexplained erosion process that some authors have called miniature debris flows on hillslopes and that leave behind levee lined rills has been observed in some regions of the world despite the unusual proposition of debris flow on planar hillslopes the process has not received much attention the objectives of this study were to 1 accumulate observational evidence of hillslope debris flows hdf as we have defined the process to 2 understand their initiation process by conducting runoff experiments on hillslopes to 3 propose a conceptual model of hdf and to 4 contrast and classify hdf relative to other erosion and transport processes in the post wildfire hillslope domain hdf have been observed at relatively steep slope gradients 0 4 0 8 on a variety of geologies and after fire of at least moderate severity and consist of a lobe of gravel to cobble sized material 0 2 1 m wide that is pushed by runoff damming up behind it during initiation runoff moved individual particles that accumulated a small distance downslope until the accumulation of grains failed and formed the granular lobe of the hdf hdf are a threshold process and runoff rates of 0 5 l s 1 2 l s 1 were required for their initiation during the experiments the conceptual model highlights hdf as a geomorphic process distinct from channel debris flows because they occur on planar unconfined hillslopes rather than confined channels hdf can erode very coarse non cohesive surface soil which distinguishes them from rill erosion that have suspended and bedload transport on a matrix of slope and grain size hdf are enveloped between purely gravity driven dry ravel and mostly runoff driven bedload transport in rills

detachment and transportation of loose sediments by raindrop splash summary laboratory experiments on sediments ejected by splash consisted of two parts quantities ejected and mean projected distances were measured since the splash tray was 100 cm long and 20 cm wide and since both measurements were made on a receiving screen of one square metre it was obvious that only part of the translocated sediment was caught it was subject to serious doubt that the measured distances were representative for all sediment translocated if it is stated that the ejected sediment is distributed according to an exponential function around any point of impact located on the tray and if by definition tray and rainfall are perfectly homogeneous the ratio of the true to the measured distance and the ratio of the caught to the translocated sediment are only a function of the exponent of the real function the apparent distance being also a function of this exponent is thus the only factor needed to solve the two questions hence all empirical data were transformed into true data

prediction of spatially explicit rainfall intensity duration thresholds for post fire debris flow generation in the western united states abstract early warning of post fire debris flow occurrence during intense rainfall has traditionally relied upon a library of regionally specific empirical rainfall intensity duration thresholds development of this library and the calculation of rainfall intensity duration thresholds often require several years of monitoring local rainfall and hydrologic response to rainstorms a time consuming approach where results are often only applicable to the specific region where data were collected here we present a new fully predictive approach that utilizes rainfall hydrologic response and readily available geospatial data to predict rainfall intensity duration thresholds for debris flow generation in recently burned locations in the western united states unlike the traditional approach to defining regional thresholds from historical data the proposed methodology permits the direct calculation of rainfall intensity duration thresholds for areas where no such data exist the thresholds calculated by this method are demonstrated to provide predictions that are of similar accuracy and in some cases outperform previously published regional intensity duration thresholds the method also provides improved predictions of debris flow likelihood which can be incorporated into existing approaches for post fire debris flow hazard assessment our results also provide guidance for the operational expansion of post fire debris flow early warning systems in areas where empirically defined regional rainfall intensity duration thresholds do not currently exist

characterizing the primary material sources and dominant erosional processes for post fire debris flow initiation in a headwater basin using multi temporal terrestrial laser scanning data abstract wildfire dramatically alters the hydrologic response of a watershed such that even modest rainstorms can produce hazardous debris flows relative to shallow landslides the primary sources of material and dominant erosional processes that contribute to post fire debris flow initiation are poorly constrained improving our understanding of how and where material is eroded from a watershed during a post fire debris flow requires 1 precise measurements of topographic change to calculate volumetric measurements of erosion and deposition and 2 the identification of relevant morphometrically defined process domains to spatially constrain these measurements of erosion and deposition in this study we combine the morphometric analysis of a steep small 0 01 km 2 headwater drainage basin with measurements of topographic change using high resolution 2 5 cm multi temporal terrestrial laser scanning data made before and after a post fire debris flow the results of the morphometric analysis are used to define four process domains hillslope divergent hillslope convergent transitional and channelized incision we determine that hillslope divergent and hillslope convergent process domains represent the primary sources of material over the period of analysis in the study basin from these results we conclude that raindrop impact induced erosion ravel surface wash and rilling are the primary erosional processes contributing to post fire debris flow initiation in the small steep headwater basin further work is needed to determine 1 how these results vary with increasing drainage basin size 2 how these data might scale upward for use with coarser resolution measurements of topography and 3 how these results change with evolving sediment supply conditions and vegetation recovery