generation and processing of pseudo shear wave data theory and case study processing of converted ps waves currently adopted by the exploration industry is essentially based on resorting the ps data into common conversion point gathers and using them for velocity analysis here we explore an alternative procedure our key idea is to generate the so called pseudo shear s seismograms from the recorded pp and ps traces and run conventional velocity analysis on the reconstructed s data this results in an effective s wave velocity model because our method creates data that possess kinematics of pure shear wave primaries we never deal with such complexities of converted waves as moveout asymmetry reflection point dispersal and polarity reversal therefore these generally troublesome features become irrelevant we describe the details of our methodology and examine its behavior both analytically and numerically we apply the developed processing flow to a four component ocean bottom cable line acquired in the gulf of mexico since the obtained stacking velocities of p and

permafrost and climate in europe monitoring and modelling thermal geomorphological and geotechnical responses we present a review of the changing state of european permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of svalbard and the discontinuous high altitude mountain permafrost of iceland fennoscandia and the alps the paper focuses on methodological developments and data collection over the last decade or so including research associated with the continent scale network of instrumented permafrost boreholes established between 1998 and 2001 under the european union pace project data indicate recent warming trends with greatest warming at higher latitudes equally important are the impacts of shorter term extreme climatic events most immediately reflected in changes in active layer thickness a large number of complex variables including altitude topography insolation and snow distribution determine permafrost temperatures the development of regionally calibrated empirical statistical models and physically based process oriented models is described and it is shown that though more complex and data dependent process oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed we report on recent research into ground ice formation including ice segregation within bedrock and vein ice formation within ice wedge systems the potential impacts of climate change on rock weathering permafrost creep landslides rock falls debris flows and slow mass movements are also discussed recent engineering responses to the potentially damaging effects of climate warming are outlined and risk assessment strategies to minimise geological hazards are described we conclude that forecasting changes in hazard occurrence magnitude and frequency is likely to depend on process based modelling demanding improved understanding of geomorphological process response systems and their impacts on human activity

characteristics of surface soil creep on a forest slope in japan abstract soil creep was monitored for 6 years using the strain probe method and compared to soil moisture conditions in order to reveal details of the soil creep mechanism on a forest slope in a weathered granite area of central japan the results revealed a relationship between soil creep and soil moisture changes bending strain of the topsoil was induced downslope by soil drying and was reversed by soil wetting however an amount of bending strain remained which accumulated annually to form net soil creep on the upper slope when rainfall exceeded a certain threshold miniature sliding sometimes occurred caused by soil destruction in areas where shear deformation became concentrated on the middle slope topsoil deformation was more complex in order to monitor the soil creep phenomenon related to the concentration of shear deformation in a narrow zone improvement of the strain probe method is needed

periglacial processes and landforms in the south shetland islands northern antarctic peninsula region abstract periglacial processes and landforms together with the presence of permafrost are among the most relevant geomorphological elements in the northern antarctic peninsula region their distribution affects the hydrology and has consequences for the ecosystems of the ice free areas in this paper a compilation of the different types of periglacial landforms and processes occurring in the south shetland islands is carried out and their spatial distribution is analysed furthermore the relationships of the periglacial landforms with local conditions and permafrost distribution have been taken into account a total of thirty three types of periglacial landforms were identified and considered in this work patterned ground and stone fields are the most common periglacial landforms which are located within a wide altitudinal range and mainly on platforms field studies aerial photograph and satellite imagery interpretation were implemented to produce detailed maps from ten areas with different geological geomorphological and relief characteristics including the largest and most relevant ice free areas within the archipelago showing the presence and spatial distribution of periglacial landforms this work shows that the periglacial environment primarily conditioned by the regional climatic conditions has a great diversity in the studied region and that the distribution of the periglacial landforms is also related to local relief and geomorphological characteristics lithology hydrogeology and presence of permafrost where altitude plays an important role periglacial phenomena are widespread above 10 m a s l and are especially active on slopes and platforms between 30 and 100 m a s l the spatial distribution of periglacial landforms helps to identify the presence of permafrost that is dominant above 25 30 m a s l and more than 70 of the surface is occupied by active layer related landforms

ventifacts and wind abraded rock features in the taylor valley antarctica abstract an area north of lake fryxell in the taylor valley antarctica was surveyed to determine the frequency of occurrence of rocks that show strong evidence of wind abrasion and ventifaction which is defined here as rocks having well developed faceting to define their relative abundance in this area of the ice free mcmurdo dry valley system and to provide an indication of the role of wind as a geomorphic agent in this area the orientation of abrasion caused features facets keels and grooves with respect to the present day wind regime is also described rocks were examined on five linear transects ranging from 300 to 510 m in length a total of 1324 rocks were examined on average 60 of all rocks exhibited distinct wind abrasion features with polish being the most common feature and polished rocks were distributed equally between survey lines suggesting abrasion was ubiquitous in the study area approximately 4 of the rocks had distinct facets and or keels and fine grained ultramafic peridotite type rocks produced the most finely featured forms i e sharp facet edges and keels a larger percentage 12 5 had grooves grooves were typically associated with a tabular form of mafic diabase type igneous rock the distribution of faceted ventifacts and grooved rocks was not uniform for the five transects suggesting that the distribution mechanism for the surface rocks and the source areas determined to a large extent what form of ventifact could be produced at a location the orientation of the grooves and dip directions of the facets indicates the direction of the abrasive winds had a strong westerly component which coincides with the modern wind regime of winter katabatic flows that move down valley toward the ross sea the orientation of the facets and grooves suggests that the rate of formation of the ventifacts proceeds at a pace greater than other surficial processes e g down slope soil movement cryoturbation which should tend to remove trends in the facet and groove orientations or that the down slope movement of the surface is approximately perpendicular to the wind allowing preservation of the alignment

the acidalia mensa region on mars a key element to test the mars ocean hypothesis abstract we present the results of a detailed photogeological study of a region surrounding acidalia mensa 43 50 n 15 35 w based on analysis of a mosaic of the ctx images nominal resolution 5 m px the main result of the study is the unfolding of the geologic history of the study region and determination of absolute model ages of its major episodes the documented history begins with the formation of a volcanic plateau of acidalia mensa 4 ga ago the surface of the acidalia plateau was strongly modified since its formation the crater size frequency distribution csfd on the plateau indicates that the resurfacing was likely consisted of multiple episodes the latest such episode recognizable by the crater statistics occurred 3 65 ga ago the vast majority of the surface around acidalia mensa is covered by materials of the background plains that correspond to the interior unit of the vastitas borealis formation vbf the csfd on the background plains corresponds to an absolute model age ama of 3 58 ga which is completely within the range of amas determined for the vbf along its boundary with the southern uplands small scale features such as bright cones mounds polygonal troughs and flow like mantling materials postdate the emplacement of the background plains and manifest the post formational evolution of the vbf the majority of crater ejecta in the study area have higher albedo in the ctx and hirise images but appear as dark spots in the themis ir nighttime images these wavelength dependent properties of the ejecta indicate the presence of light toned and fine grained material beneath the surface of the background plains this material was the source of numerous bright cones mounds we interpret the formation of this reservoir as the result of sorting of large amounts of water mud deposited in the study area and by implication within the northern lowlands the final episodes of the ancient geologic history of the study area were related to the emplacement of materials of the thick flows at topographically high levels within the acidalia plateau 3 47 ga ago the morphology of the flows is inconsistent with lava and we interpret the occurrences of the thick flows as the result of displacement of water saturated regolith in the form of either soli or gelifluction flows or ice cored rock glaciers

the joint nonhyperbolic moveout inversion of pp and ps data in vti media nonhyperbolic moveout of p waves in horizontally layered transversely isotropic media with a vertical symmetry axis vti can be used to estimate the anellipticity coefficient in addition to the nmo velocity vnmo p those two parameters are sufficient for time processing of p wave data despite a certain instability in the inversion for but they do not constrain the vertical velocity vp0 and the depth scale of the model it has been suggested in the literature that this ambiguity in the depth domain velocity analysis for layer cake vti media can be resolved by combining long spread reflection traveltimes of p waves and mode converted psv waves here we show that reflection traveltimes of horizontal psv events help to determine the ratio of the p and s wave vertical velocities and the nmo velocity of sv waves and they give a more accurate estimate of however nonhyperbolic moveout of psv waves turns out to be mostly controlled by wide angle p wave traveltimes and does not provide independent inf

late holocene solifluction lobe activity in the mount rae area southern canadian rocky mountains solifluction lobes are tongue shaped accumulations of sediment resulting from localized periglacial mass wasting radiocarbon records from beneath two turf banked lobes in the mount rae area of the southern canadian rockies indicate that solifluction processes have been continuously active for at least the last 2000 years the long term rates of frontal movement at both sites average 0 49 cm year but vary in magnitude from 0 35 to 1 50 cm year both lobes terminate above soil pedons progressively overridden by their advance estimates of the apparent mean residence time of the contemporary soil ranges from 962 100 years in one case to 1600 100 years in the other this information was used to reconstruct a chronology of lobe activity collectively the radiocarbon records indicate that solifluction lobes in this area were advancing quite rapidly between 1900 1750 years bp but declined to a much slower but relatively constant pace up until the present

chemical weathering of silicate rocks in aldan shield and baikal uplift insights from long term seasonal measurements of solute fluxes in rivers abstract a reassessment of available information from the russian hydrological survey on long term seasonal measurements of water suspended matter and dissolved major element discharges in 30 small and large watersheds draining acid silicate rocks granites gneisses quartzites shales of the aldan shield and baikal uplift was combined with new data on river water chemistry for three granitic watersheds in order to calculate the fluxes of elements due to chemical weathering in accord with data on world rivers a positive correlation between chemical erosion rate and runoff is observed the majority of cations are removed during summer monsoon the spring flood yields 10 20 of the annual flux and the winter season accounts for only 5 15 the mean multi annual flux of total dissolved solid which is largely dominated by ca 60 80 on the siberian craton is comparable with that of temperate zones but higher than that of the canadian shield for similar runoff values rock composition and annual temperatures important element recycling due to litter degradation and weathering acceleration via organic ligands produced by abundant vegetation over permafrost soils is invoked to explain these results

tree root mounds and their role in transporting soil on forested landscapes the growth and decay of tree roots can stir and transport soil this is one process that contributes to the mass movement of soil on hillslope to explore the efficiency of this process we document the mounding of soil beside ponderosa and lodgepole pine trees in the forests that dominate the mid elevations of colorado s boulder creek watershed mounds are best expressed around ponderosa pines reaching vertical displacements above the far field slopes of order 10 20 cm fading into the slope by roughly 100 cm distance from the trunks with common diameters of 30 cm positive mounding occurs on all sides of trees on slopes indicating that the mounding is not attributable to deflection of a creeping flow of soil around the tree but rather to the insertion of root volume on all sides in the subsurface mounding is commonly asymmetric even on cross slope profiles significant variation in the mound sizes results in no clear relationship between tree diameter and root volume displaced these observations motivated the development of a discrete element model of tree root growth using the liggghts model in which grains we specified to be root cells were allowed to enlarge within the simulated granular matrix mounding could be reproduced with the majority of the vertical displacement of the surface being attributable to reduction of the bulk density due to dilation of the granular matrix during root enlargement finally we develop a previous analysis of the role of roots in transporting soil during growth and decay cycles we find that even in shallow soils the root cycle can drive significant soil transport down forested montane slopes copyright 2013 john wiley sons ltd

sensitivity of the free core nutation and the chandler wobble to changes in the interior structure of mars abstract in view of the forthcoming mars missions with seismological and geodetic experiments on board the sensitivity of mars normal modes to interior structure changes is examined the emphasis is put on the chandler wobble cw and the free core nutation fcn as both can play an important role in the nutations and tides of mars the fcn especially is found to have a large potential for inferring properties of the interior structure of mars if observed it will prove that mars contains a liquid core and information about the core radius and density jump at the core mantle boundary cmb can be obtained spheroidal oscillation modes of mars are also shown to provide a powerful and additional constraint on the martian interior

migration velocity analysis in factorized vti media one of the main challenges in anisotropic velocity analysis and imaging is simultaneous estimation of velocity gradients and anisotropic parameters from reflection data approximating the subsurface by a factorized vti transversely isotropic with a vertical symmetry axis medium provides a convenient way of building vertically and laterally heterogeneous anisotropic models for prestack depthmigration the algorithm for p wave migration velocity analysis mva introduced here is designed for models composed of factorized vti layers or blocks with constant vertical and lateral gradients in the vertical velocity vp0 the anisotropic mva method is implemented as an iterative two step procedure that includes prestack depth migration imaging step followed by an update of the medium parameters velocity analysis step the residual moveout of the migrated events which is minimized during the parameter updates is described by a nonhyperbolic equation whose coefficients are determined by 2d semblance scanning

sorted stripes on sub antarctic kerguelen island observations of sorted stripes at nine different localities on sub antarctic kerguelen island are presented the study sites range from 25 600 m above sea level and are of varying aspect it is found that there is a strong relationship between stripe orientation and the wind direction to the extent that at one locality stripes were orientated across a slope stripe width was seen to increase with altitude and in addition the coarse stripe was dominant at lower elevations and the fine stripe at higher elevations at one site a secondary set of stripes was observed to occur within the fine stripe of a primary larger set on a trachyte plug there was evidence of lateral squeezing in the formation of the stripes a number of minor observations pertaining to the possible mechanism of stripe formation are given

geomorphological and cryostratigraphical analyses of the zackenberg valley ne greenland and significance of holocene alluvial fans abstract in high arctic northern greenland future responses to climatic changes are poorly understood on a landscape scale here we present a study of the geomorphology and cryostratigraphy in the zackenberg valley in ne greenland 74 n containing a geomorphological map and a simplified geocryological map combined with analyses of 13 permafrost cores and two exposures cores from a solifluction sheet alluvial fans and an emerged delta were studied with regards to cryostructures ice and total carbon contents grain size distribution and pore water electrical conductivity and the samples were ams 14c dated the near surface permafrost on slopes and alluvial fans is ice rich as opposed to the ice poor epigenetic permafrost in the emerged delta ground ice and carbon distribution are closely linked to sediment transport processes which largely depend on lithology and topography holocene alluvial fans on the lowermost hillslopes covering 12 of the study area represent paleoenvironmental archives during the contrasting climates of the holocene the alluvial fans continued to aggrade through the warmer early holocene optimum the colder late holocene and the following climate warming and by 0 45 mm a 1 on average this is caused by three factors sedimentation ground ice aggradation and vegetation growth and is reflected by ams 14c dating and continuously alternating cryostructures highly variable sedimentation rates in space and time at the alluvial fans have been detected this is also reflected by alternating lenticular and microlenticular cryostructures indicating syngenetic permafrost aggradation during sedimentation with suspended and organic matrix cryostructures indicating quasi syngenetic permafrost aggradation in response to vegetation growth in periods with reduced or no sedimentation over time this causes organic matter to become buried indicating that alluvial fans represent effective carbon sinks that have previously been overlooked

frost sorting on slopes by needle ice a laboratory simulation on the effect of slope gradient following a previous attempt to reproduce miniature sorted patterns on a level surface we report the results of a full scale laboratory simulation on frost sorting produced by needle ice activity on inclined surfaces four models with different slope gradients 5 7 9 11 were designed stones 6 mm in diameter placed in a grid covered 20 of the surface of frost susceptible water saturated soil these models were subjected to 20 40 freeze thaw cycles between 10 c and 5 c in 12 hours the evolution of surface patterns was visually traced by photogrammetry needle ice growth and collapse induced downslope movement and concentrations of stones a model produced incipient sorted circles on a 5 slope whereas it resulted in three distinct sorted stripes on a 7 slope the average diameter or spacing of these forms is 9 7 19 4 cm comparable to those in the field dominated by diurnal freeze thaw cycles surface parallel displacements of stone markers were traced with motion analysis software the observed downslope stone displacements agree with those expected assuming that surface soil and stones move by repeated heaving perpendicular to the surface and vertical settlement due to gravity although the growth of curved needle adds complexity to the overall displacements

interior structure and seasonal mass redistribution of mars from radio tracking of mars pathfinder doppler and range measurements to the mars pathfinder lander made using its radio communications system have been combined with similar measurements from the viking landers to estimate improved values of the precession of mars pole of rotation and the variation in mars rotation rate the observed precession of 7576 35 milliarc seconds of angle per year implies a dense core and constrains possible models of interior composition the estimated annual variation in rotation is in good agreement with a model of seasonal mass exchange of carbon dioxide between the atmosphere and ice caps

origin and 10be surface exposure dating of a coarse debris accumulation in the hrubý jesenik mountains central europe abstract coarse debris accumulations cover large areas in high latitude and mountain environments but their age and origin remain mostly unknown here we reassess the morphology of a prominent coarse debris accumulation in the sudetes mountain range in central europe and constrain its timing with 10be surface exposure data our observations indicate that the landform in the south eastern slope of the su ridge appears consistent with the morphology of a block slope the oldest minimum age of 150 1 4 8 ka obtained for the tor at the upper limit of the block slope indicates the disintegration of the ridge and surface lowering under periglacial conditions prior to the last glacial interglacial cycle four exposure ages retrieved for block samples range from 84 3 3 8 to 26 8 2 6 ka providing evidence for block emplacement during the last cold period the exposure ages extend existing chronological dataset for peri glacial landforms in the sudetes and constrain the timing of cold environments in the area prior the last glacial maximum the ages are also consistent with surface exposure data reported for block fields and block slopes in western europe and confirm the formation of similar landforms over the last glacial period in the sudetes

the distribution of putative periglacial landforms on the martian northern plains in this investigation hirise images were surveyed across three regions of the northern plains of mars acidalia arcadia and utopia planitiae a sample of hirise images within each of these areas was examined the aim of the investigation was to determine the distribution of three varieties of landform clastic patterned ground lobate hill slope features and scalloped depressions these features are of importance as they are morphologically similar to terrestrial periglacial features examples of these landforms were found across the study areas scalloped depressions are common at mid latitudes in each of the three regions sorted patterned ground was not as widespread some examples of sorted patterned ground were found in all three study areas but the main concentration occurs in the north western region of acidalia planitia lobate hill slope features were the least common of the three landform types despite occurring infrequently several possible examples of lobate features were found to occur in proximity to other putative periglacial features it was found that lobate hill slope features and clastic patterns occurred further south than expected beyond the southern extent of many previous studies these features and by extension the processes that form them could thus occur more widely than previously thought it also appears that although putative periglacial features are often found in crater interiors they are not limited to these environments extensive areas of patterned ground were found on the inter crater plains lobate features and sorted stripes were often found on crater walls which would support the hypothesis that they are analogous to hill slope features on earth scalloped depressions were most often found in crater interiors or on crater ejecta although examples on the inter crater plains were not uncommon

multi process late quaternary landscape evolution modelling reveals lags in climate response over small spatial scales landscapes evolve in complex non linear ways over quaternary timespans integrated geomorphological field studies usually yield plausible hypotheses about timing and impact of process activity landscape evolution models lems have the potential to test and falsify these landscape evolution hypotheses despite this potential lems have mainly been used with hypothetical data and rarely to simulate the evolution of an actual landscape in this paper we use a lem lapsus landscape process modelling at multi dimensions and scales to explore if it is possible to test and falsify conclusions of an earlier field study on 50 ka landscape evolution in okhombe valley kwazulu natal south africa in this lem five landscape processes interact without supervision water driven erosion and deposition creep solifluction biological weathering and frost weathering calibration matched model results to three types of qualitative fieldwork observations individual process activity over time relative process activity over time and net landscape changes over time results demonstrate that landscape evolution of the okhombe valley can be plausibly simulated a particularly interesting and persistent feature of model results are erosional and depositional phases that lag climatic drivers both by decades and by several ka within a few hundred meters the longer lag has not been reported for this spatial scale before and may be an effect of slow landscape soil vegetation feedbacks the combined modelling and fieldwork results allow a more complete understanding of these responses to climate change and can fill in hiatuses in the stratigraphical record suggestions are made for methodological adaptations for future lem studies

tidally induced surface displacements external potential variations and gravity variations on mars abstract we have used and extended roosbeek s tidal potential for mars to calculate tidal displacements gravity variations and external gravitational potential variations the tides on mars are caused by the sun and to a lesser degree by the natural satellites phobos 8 relative to the sun and deimos 0 08 relative to the sun to determine the reaction of mars to the tidal forcing the love numbers h l and k and the gravimetric factor were calculated for interior models of mars with different state density and radius of the core and for models which include mantle anelasticity the latitude dependence and frequency dependence of the love numbers have been taken explicitly into account the love numbers are about three times smaller than those for the earth and are very sensitive to core changes e g a difference of about 30 is found between a model with a liquid core and an otherwise similar model with a solid core tidal displacements on mars are much smaller than on earth due to the smaller tidal potential but also due to the smaller reaction of mars smaller love numbers for both the tidal diplacement and the tidal external potential perturbations the tidal signal is at the limit of detection and is too small to permit properties of mars s interior to be inferred on the other hand the phobos tidally induced gravity changes which are subdiurnal with typical periods shorter than 12 h can be measured very precisely by the very broad band seismometer with thermal control of the seismological experiment seis of the upcoming netlander mission it is shown that the phobos induced gravity tides could be used to study the martian core

gelifluction viscous flow or plastic creep this paper reports results from two scaled centrifuge modelling experiments designed to simulate thaw related gelifluction a planar 12 prototype slope was modelled in each experiment using the same natural fine sandy silt soil however two different scales were used in experiment 1 the model scale was 1 10 tested in the centrifuge at 10 gravities g and in experiment 2 the scale was 1 30 tested at 30 g centrifuge scaling laws indicate that the time scaling factor for thaw consolidation between model and prototype is n2 where n is the number of gravities under which the model was tested however the equivalent time scaling for viscous flow is 1 1 if gelifluction is a viscosity controlled flow process scaling conflicts will therefore arise during centrifuge modelling of thawing slopes and rates of displacement will not scale accurately to the prototype if however no such scaling conflicts are observed we may conclude that gelifluction is not controlled by viscosity but rather by elasto plastic soil deformation in which frictional shear strength depends on effective stress itself a function of the thaw consolidation process models were saturated consolidated and frozen from the surface downwards on the laboratory floor the frozen models were then placed in the geotechnical centrifuge and thawed from the surface down each model was subjected to four freeze thaw cycles soil temperatures and pore water pressures were monitored and frost heave thaw settlement and downslope displacements measured pore water pressures displacement rates and displacement profiles reflecting accumulated shear strain were all similar at the two model scales and volumetric soil transport per freeze thaw cycle when scaled to prototype were virtually identical displacement rates and profiles were also similar to those observed in earlier full scale laboratory floor experiments it is concluded therefore that the modelled gelifluction was not a time dependent viscosity controlled flow phenomenon but rather elasto plastic in nature a first approximation flow law is proposed based on the cam clay constitutive model for soils

mars and mercury rotation variations from altimetry crossover data feasibility study 1 knowledge of the interior structure of terrestrial planets can be achieved by studying the changes of their rotation and orientation in time we simulate the use of time deviations of altimetry crossover positions to infer information on the nutations of mars and on the librations of mercury the analysis is based on the least squares estimator and uses simulated crossover points the simulations demonstrate that the use of crossover data improves the estimates of the observed libration amplitude and obliquity of mercury and allows detecting the nutations of mars

solifluction meets vegetation the role of biogeomorphic feedbacks for turf banked solifluction lobe development vegetation is an important factor influencing solifluction processes while at the same time solifluction processes and landforms influence species composition fine scale distribution and corresponding ecosystem functioning however how feedbacks between plants and solifluction processes influence the development of turf banked solifluction lobes tbls and their geomorphic and vegetation patterns is still poorly understood we addressed this knowledge gap in a detailed biogeomorphic investigation in the turtmann glacier foreland switzerland methods employed include geomorphic and vegetation mapping terrain assessment with unmanned aerial vehicle uav and temperature logging results were subsequently integrated with knowledge from previous geomorphic and ecologic studies into a conceptual model our results show that geomorphic and vegetation patterns at tbls are closely linked through the lobe elements tread risers and ridge a conceptual four stage biogeomorphic model of tbl development with ecosystem engineering by the dwarf shrub dryas octopetala as the dominant process can explain these interlinked patterns based on this model we demonstrate that tbls are biogeomorphic structures and follow a cyclic development during which the role of their components for engineer and non engineer species changes our study presents the first biogeomorphic model of tbl development and highlights the applicability and necessity of biogeomorphic approaches and research in periglacial environments copyright 2016 john wiley sons ltd

active layer slope movement in a continuous permafrost environment garry island northwest territories canada field investigations have been carried out at garry island n w t for the 1964 1980 period in order to study downslope active layer movement at sites with two sided downward and upward freezing and active ice wedge growth movements have been determined with reference to semi flexible plastic tubes inserted vertically into the ground and by deformation of lines of stakes the results show that the vertical velocity profile on the hillslopes with clayey hummocks is convex downslope the movement is plug like and occurs in late summer the plug like movement progressively buries the interhummock peat to form a buried organic layer and most of the plug like movement can be attributed to frost creep by thaw of an ice rich layer at the bottom of the active layer the ice rich layer forms by upfreezing in winter and the ice content may be augmented by ice lensing in the summer thaw period in a sedgy drainage swale the vertical velocity profile is concave downslope the active layer of ice wedge polygons s

on models of mars interior and amplitudes of forced nutations 1 the effects of deviation of mars from its equilibrium state on the flattening of the core mantle boundary abstract in a static approach the effects of deviation of mars from its equilibrium state on the flattening of the core mantle boundary cmb are studied the calculations are performed for a set of interior structure models with 50 and 100 km thick crust and averaged crustal density varying in the range of 2700 3200 kg m 3 which are based on new values for the moment of inertia and the elastic tidal love number k 2 s defined by konopliv et al konopliv a s yoder c f standish e m yuan d n sjorgen w l 2006 a global solution for the mars static and seasonal gravity mars orientation phobos and deimos masses and mars ephemeris icarus 182 23 50 the models differ in density contrast at the crust mantle boundary and the core radius the observational data constrain the radius of a liquid core to be within 1700 1800 km for joint interpretation of gravity and topography data an outer surface of a hydrostatical model is chosen as a reference surface the green s functions or loading factors technique for the case of a single anomalous density wave located at two depth level is used to compute the second degree cmb deformation and then the cmb flattening two types of models have been calculated an elastic model and a model with an elastic lithosphere and weakened layers below it relaxed values of shear modulus the effective shear modulus of the mantle is reduced in comparison with an elastic one and in extreme case it is approaching zero everywhere except the elastic lithosphere non equilibrium state of mars results in three axiality of the core mantle boundary for an elastic case the deformation of cmb leads to the large decrease of the semiaxis b going through the central region of tharsis rise by 660 780 m and the increase of the equatorial semiaxis a by 240 300 m and the polar axis c by 400 490 m tharsis rise plays a constitutive role for the cmb deformation the second degree harmonics in the expansion of non equilibrium part of gravity field and topography are sensitive first of all to the properties of the crust in the tharsis region non hydrostatic contributions decrease the flattening of the cmb by about 5 6 the effect of loading increases when the value of shear modulus decreases by a factor of 10 but as the shear modulus is decreasing up to zero the flattening is approaching its hydrostatic value

solifluction and related processes eastern banks island n w t mean surface soil movement measured over the period 1972 1983 on eight relatively low angle 10 well drained slopes on eastern banks island averaged 0 6 cm year substantial variation in mean movement was recorded amongst the slopes the variation relates to differences in soil moisture conditions soil grain size and the position of the measurement transect relative to the crest or base of the slope the former two variables and therefore the rate of movement can change rapidly across any given slope particularly when stripes are present three types of movement are identified in the study area 1 mud burst and mud flow 2 classic solifluction and 3 pluglike flow the latter occurs along discrete shear planes located both within and at the base of the active layer the existence of episodic and relatively rapid mass movement on these slopes suggests that long term monitoring programs are necessary to adequately assess and measure slope movement

periglacial transport distance of pb derived from small scale ore veins in the rhenish slate mountains abstract the spatial extent of metal contamination caused by small scale ore veins is increased by periglacial solifluction our objectives were 1 to examine the spatial distribution of pb in cover beds that migrated over pb ore veins 2 to calculate the transport distance of ore derived pb and 3 to determine controls on the transport distance we examined six transects 320 775 m long in the rhenish slate mountains in west germany the transects included four west exposed and two east exposed slopes with inclinations between 2 20 all transects were forest covered and located at 280 450 m above sea level soils were dystric cambisols and stagnic luvisols samples of 120 b horizons developed in the sediments of the last ice age wuerm were analyzed for total pb concentrations and partly also 206 pb 207 pb ratios the pb concentrations ranged from 20 to 135 mg kg 1 the spatial pb distribution suggested that 14 out of 18 sampling points showing local pb concentration maxima contained pb from ore veins upslope with a two end member mixing model using 206 pb 207 pb isotope ratios of the ore 206 pb 207 pb ratio 1 1828 as one end member and of the native substrate a mixture of slate and loess 206 pb 207 pb ratio 1 2254 0 0072 as the other we confirmed that the 14 pb peaks originated from the ore because they contained 76 100 of ore derived pb by the use of a geographic information system the transport distance of this pb was determined to range between 30 and 110 m silt concentrations pearson r 0 69 and the relief curvature cramer s v 0 60 were major controls on the transport distance our study demonstrates that pb ore veins can increase native soil pb concentrations in soil derived from the periglacial drift of the last ice age wuerm up to a distance of more than 100 m

an investigation of periglacial slope stability in relation to soil properties based on physical modelling in the geotechnical centrifuge results are presented from eight scaled centrifuge modelling experiments designed to investigate mass movement processes on thawing ice rich slopes four pairs of simple planar slope models were constructed one in each pair being of sufficient gradient to promote slope failure during soil thaw and the second having a gradient below the threshold for instability four frost susceptible soils were used three were normally consolidated and had different clay contents 2 12 and 20 and the fourth comprised the 20 clay soil but was over consolidated prior to model testing modelling protocols included freezing from the surface downwards under an open hydraulic system and thawing from the surface downwards under an enhanced gravitational field within the geotechnical centrifuge thereby utilising scaling laws to simulate correct prototype self weight stresses during thaw slopes below the stability threshold gradient were subjected to between 2 and 4 cycles of freezing and thawing simulating annual cycles those above the stability threshold were subjected to only one cycle since they failed during the first thaw phase thermal conditions pore water pressures surface movements and profiles of displacement are reported measured pore pressures are used in slope stability analyses based on a simple planar infinite slope model profiles of solifluction shear strain and mechanisms of slope failure are both shown to be sensitive to small changes in soil properties particularly clay content and stress history in all cases pore pressures rose rapidly immediately following thaw remained below the threshold for failure in low gradient models but exceeding the threshold to trigger landslides on steeper slopes upward seepage of melt water away from the thaw front contributed to loss of shear strength mechanisms of slope failure differed between test soils ranging from mudflow in non cohesive silt to active layer detachment sliding in over consolidated silt clay during solifluction shear strain was greatest at the surface in non cohesive silt and decreased rapidly with depth but in test soils containing clay the zone of maximum shear strain was located lower in the displacement profiles

burial and turbulent transport by bioturbation a 27 year experiment in southeast australia in order to assess the net effect and relative importance of geomorphic processes at two natural woodland sites in southeast australia 100 small tiles were placed on the soil surface in 1979 and their movement was monitored over the course of nearly three decades rates of tile burial and other tile displacement were considerable but also markedly random being largely inconsistent with expected patterns of displacement by orthodox creep and rainwash processes this included substantial upslope displacement and burial depths that ranged from zero to 5 cm we suggest that such turbulent transport in the topsoil has mostly been caused by the direct and indirect transfer of soil and clasts by animals and plants i e bioturbation in addition to direct evidence of biota interacting with tiles the effectiveness of bioturbation at our sites has been well established and the overall tile burial rate of 0 25 to 0 4 mm yr 1 is comparable to rates of surface mounding patterns of tile movement are generally consistent with soils geomorphic theory regarding the biomantle and bioturbation driven stonelayer formation and provide further evidence that soil transfer and slope movement in many situations are markedly random and complex processes copyright 2010 john wiley sons ltd

analysis of image gathers in factorized vti media because events in image gathers generated after prestack depth migration are sensitive to the velocity field they are often used in migration velocity analysis for isotropic media here we present an analytic and numerical study of p wave image gathers in transversely isotropic media with a vertical symmetry axis vti and establish the conditions for flattening such events and positioning them at the true reflector depth application of the weak anisotropy approximation leads to concise expressions for reflections in image gathers from homogeneous and factorized v z media in terms of the vti parameters and the vertical velocity gradient kz flattening events in image gathers for any reflector dip requires accurate values of the zero dip nmo velocity at the surface vnmo z 0 the gradient kz and the anellipticity coefficient for a fixed error in vnmo and kz the magnitude of residual moveout of events in image gathers decreases with dip while the moveout caused by an error in initially incr

ground temperature regimes and geomorphological implications in a mediterranean mountain serra da estrela portugal air and shallow ground temperatures from two monitoring sites at the serra da estrela portugal are analysed the cantaro gordo site is located at 1875 m asl and the fraga das penas at 1640 m asl the climate of the study area is mediterranean and very irregular both on a yearly and monthly basis this is particularly significant during winter when differences in snow cover have direct influence on the ground thermal regimes and therefore on geocryological processes to assess the significance of the ground thermal regimes for the geomorphological dynamics bi hourly records of temperature are studied at a daily basis eight types of daily regime were identified isothermal unfrozen non isothermal unfrozen surficial freeze thaw surficial freeze thaw and subsurficial frost surficial and subsurficial freeze thaw subsurficial frost surficial and subsurficial frost and surficial frost but no daily rhythm the occurrence of these regimes is analysed and their geomorphological significance is presented based on the altitudinal differences of the two monitoring sites on the occurrence of the different regimes and on field observations a conceptual model for the altitudinal and seasonal zoning of the daily thermal regimes of the ground is presented this model was prepared for the serra da estrela but it can be used in other mediterranean or tropical areas if altitude and seasonal precipitation differences are taken in explanation d 2002 elsevier science b v all rights reserved

rates and processes of periglacial solifluction an experimental approach cold room physical modelling of periglacial solifluction processes on an experimental slope of 12 is described and data on soil temperatures surface frost heave thaw consolidation downslope soil movement and porewater pressures over seven freeze thaw cycles are presented these data are analyzed in the context of laboratory determination of the rheometry of the experimental soils at high moisture contents it is concluded that the observed thaw induced solifluction represents pre failure soil shear strain and results from loss of strength due to the combined effects of raised porewater pressures during thaw consolidation and upward seepage pressures as water flows towards the surface away from the thaw front an investigation of the rheometry of thawing soils offers the prospect of an analytical model to predict rates and depths of periglacial solifluction 1997 by john wiley sons ltd

soil creep problems raised by a 23 year study in australia in october 1965 and february 1966 55 young pits were installed in tropical northern territory nt and temperate new south wales nsw pits were monitored in 1968 1971 and 1974 also for the nt only in 1988 in each region half of the pits are on weathered granite and half on sandstone local relief is 30m or less and slopes are up to 20 annual rainfall is evenly distributed in the nsw sites 800 mm a 1 but is confined to the five to six month wet season in nt 1200 mm a 1 six pits suffered external disturbance and so were not analysed analysis of 160 rods in 49 undisturbed pits shows 1 vectorial movement generally not downslope parallel to the ground surface but dominated by a vertically downward component 2 significant uphill and vertically upward components of movement for many rods 3 a weak correlation between total movement and sine of slope 4 rapid movement during 1965 68 and slow movement thereafter 5 significantly higher creep rates on the nt granites than on all other sites perhaps because mound building termites are especially active there we conclude that our data do not support soil creep models which assume that all movement is downslope and slope parallel repeated long term measurements are essential to distinguish long term creep rates from the short term effects of disturbance copyright 1999 john wiley sons ltd

cave development by frost weathering abstract this paper deals with the description and genesis of a special type of shelter cave in german they are termed auswitterungshohlen which goes back to the 19th century and the genesis is supposed to be related to frost weathering but to our knowledge detailed studies are missing so far this type of cave is very common in the area of investigation that comprises pre alpine and alpine regions in the north eastern part of the eastern alps they make up 32 of the 5138 registered caves but surprisingly they entirely developed in carbonate rocks although most of them are smaller than a dozen metres some have lengths of more than 50 m and entrances can be more than 100 m wide or similarly high besides general observations that lead to a list of characteristics for these caves two of them in a pre alpine setting were studied in depth a detailed map descriptions and measurements concerning cave morphology host rock geology and climate are given the thickness and composition of clastic sediments were investigated by small trenches and electric resistivity measurements sediment thicknesses reach up to 2 m inside the caves and below the entrances for one year nets were installed to measure rockfall in both caves in warm periods generally less than 5 g month of debris could be collected but a few 100 g month for frost periods this strong correlation and the significant amount of debris together with other observations suggest that frost weathering is an on going and very important process for the formation of these caves grain size distribution of the collected debris argues for the activity of both microgelivation and ice segregation therefore we suggest that the term frost weathering caves should be used for shelter caves whose genesis is related to frost weathering as dissolution seems to be of marginal importance for the genesis they are a paradox as they develop in karstic rock but have pseudokarst features

rock glaciers and related periglacial landforms in the sierra nevada ca usa inventory distribution and climatic relationships abstract rock glaciers and related periglacial rock ice features rifs are abundant yet overlooked landforms in the sierra nevada california where they occur in diverse forms we mapped 421 rifs from field surveys and grouped these into six classes based on morphology and location these categories comprise a greater range of frozen ground features than are commonly described in rock glacier surveys mapped features extended from 2225 to 3932 m modern mean 3333 m occurred mostly on nnw to nne aspects and ranged in apparent age from modern to relict late pleistocene many of the smaller features mapped here are not readily discernible with remote e g air photo observation field surveys remain the best approach for their detection we interpreted the presence of outlet springs basal lakes suspended silt in outlet streams and fringing phreatophytic vegetation in addition to morphologic indications of current rock movement as evidence for interstitial ice either persistent or seasonal the six classes were distinct in their geographic settings and morphologic conditions indicating process level differences to assess modern climate we intersected mapped locations with the 30 arcsec prism climate model discriminant analysis indicated significant differences among the climate means of the classes with the first three canonical vectors describing 94 of the differences among classes mean annual air temperatures maat for modern features ranged from 0 3 to 2 2 c mean precipitation ranged from 1346 to 1513 mm we calculated differences between modern and pleistocene temperatures in two ways one based on elevation differences of modern and relict rifs 662 m and standard lapse rate the other using prism estimates for the first we estimate the difference in maat as 3 9 c range 2 2 to 7 9 c from prism the difference was 3 3 c range 1 0 to 6 1 c in that persistent snowfields and glaciers are retreating in the sierra nevada under warming climates rifs will likely become increasingly important in prolonging water storage during the warm season and providing small but distributed water reserves for biodiversity and runoff their presence and water contributions would benefit by further hydrologic study

soil creep dynamics soil moisture and temperature conditions on a forested slope in the granitic vosges mountains france soil creep soil water tension and soil temperature were monitored at the schildmatt experimental site over a 7 month period in order to study the dynamics of creep movements measured with a specially designed strain gauge probe the limited displacements and the very low signals which had to be measured were taken into account in estimating the uncertainty in measurements the results obtained emphasize the very discontinuous and highly reversible character of the creep movements and their seasonal nature displacements occurred mainly during two events their size were 10 mm and 2 mm but the overall displacements for the whole intensive study period january july 1985 was only 3 mm the relationships with soil moisture and temperature conditions indicated that ice segregation and saturated conditions are major influences but more needs to be known about the way they act on soil creep

the period and q of the chandler wobble summary we have extended our calculation of the theoretical period of the chandler wobble to account for the non hydrostatic portion of the earth s equatorial bulge and the effect of the fluid core upon the lengthening of the period due to the pole tide we find the theoretical period of a realistic perfectly elastic earth with an equilibrium pole tide to be 426 7 sidereal days which is 8 5 day shorter than the observed period of 435 2 day using rayleigh s principle for a rotating earth we exploit this discrepancy together with the observed chandler q to place constraints on the frequency dependence of mantle anelasticity if q in the mantle varies with frequency u as u between 30 s and 14 months and if q in the lower mantle is of order 225 at 30 s we find that 0 04 5 a 5 0 1 1 if instead q in the lower mantle is of order 350 near 200 s we find that 0 11 5 a 0 19 in all cases these limits arise from exceeding the 68 per cent confidence limits of 2 6 day in the observed period since slight departures from an equilibrium pole tide affect the q much more strongly than the period we believe these limits to be robust

on models of mars interior and amplitudes of forced nutations 2 the effects of liquid core and mantle elasticity abstract the numerical modeling of mars forced nutation of the real mars model with a radially heterogeneous compressible self gravitating liquid core and elastic mantle is performed effects of three axiality of mars figure are taken into account to compute values for the periods of free core nutation fcn and the amplitudes of forced nutations the effects of the liquid core for different models are of the order of few percents for the prograde semi annual component and of the order of 10 15 for the semi annual retrograde component the absolute values of these effects are of the order of 5 20 ms of arc mas and 1 3 mas respectively taking into account that the modern accuracy of vlbi measurements for the case of the earth is of the order of 0 02 mas we see that important results about mars internal structure may be obtained even if the accuracy of mars nutational measurements 1 2 order of magnitude less than accuracy for the earth the effects of the shear stress relaxation during long time intervals are studied the corrections to the nutational amplitudes for prograde semi annual component are between 8 93 and 9 8 for retrograde semi annual component are between 4 81 and 8 2 ms of arc and the period of free core nutation is varied in the limits between 257 2 and 295 8 earth s solar days the differences exceed significantly the errors of mars nutational components measurements and consequently these measurements can give new important information about martian mantle rheology the possibilities of inferring properties of the interior structure of mars based on the measurements of its rotation are discussed

physical modelling of fault scarp degradation under freeze thaw cycles physical modelling has been developed in order to simulate the effects of periglacial erosion processes on the degradation of slopes and scarps data from 41 experimental freeze thaw cycles are presented they attest to the efficiency of periglacial processes that control both erosion and changes in scarp morphology i cryoexpulsion leads to an increase of scarp surface roughness and modifies significantly the internal structure of the active layer ii combined effects of frost creep and gelifluction lead to slow and gradual downslope displacements of the active layer 0 3 cm cycle iii debris flows are associated with the most significant changes in scarp morphology and are responsible for the highest rate of scarp erosion iv quantification of the erosion rate gives values close to 1 cm3 cm 2 for 41 freeze thaw cycles these experimental results are consistent with field data acquired along the la hague fault scarp normandy france where an erosion rate of 4 6 1 m3 m 2 per glacial stage has been computed from the volume of natural slope deposits stored during the weichselian glacial stage these results show that moist periglacial erosion processes could lead to an underestimation of plio quaternary deformation in the mid latitudes copyright 2006 john wiley sons ltd

soil creep and convex upward velocity profiles theoretical and experimental investigation of disturbance driven sediment transport on hillslopes the movement of unconsolidated materials near the earth s surface is often driven by disturbances that occur at a range of spatial and temporal scales the nature of these disturbances ranges from highly variable such as tree turnover to periodic and predictable such as frost heave or creep to explore the effect of probabilistic disturbances on surface processes we formulated a granular creep model with analogy to rate process theory rpt used for chemical reactions according to the theory individual particles must be energized to a height greater than adjacent particles in order for grain dilation and transport to occur the height of neighbouring particles which is akin to activation energy in chemical reactions varies with slope angle such that energy barriers get smaller in the downslope direction as slopes steepen when slopes approach the friction limited angle of repose the height of energy barriers approaches zero and grains ow in the absence of disturbance an exponential function is used to describe the probability distribution of particle excitation height although alternative distributions are possible we tested model predictions of granular dynamics in an experimental sandpile in the sandpile acoustic energy serves as the disturbance agent such that grains dilate and shear in response particle velocities are controlled by the frequency of energy pulses that result in grain displacement using tracer particles we observed a convex upward velocity pro le near the surface of the sandpile consistent with predictions of our rpt based velocity model in addition we depth integrated the velocity model to predict how ux rates vary with inclination of the sandpile and observed non linear ux gradient curves consistent with model predictions by varying the acoustic energy level in the experimental sandpile we documented changes in the rate of grain movement similar changes in modelled velocities were achieved by varying the exponent of the particle excitation probability distribution the general agreement between observed and modelled granular behaviour in our simple laboratory sandpile supports the utility of rpt based methods for modelling transport processes e g soil creep frost heave and till deformation thus enabling us to account for the probabilistic nature of disturbances that liberate sediment in natural landscapes copyright 2004 john wiley sons ltd

image gathers of sv waves in homogeneous and factorized vti media reflection moveout of sv waves in transversely isotropic media with a vertical symmetry axis vti media can provide valuable information about the model parameters and help to overcome the ambiguities in the inversion of p wave data here to develop a foundation for shear wave migration velocity analysis we study sv wave image gathers obtained after prestack depth migration the key issue addressed using both approximate analytic results and kirchhoff migration of synthetic data is whether long spread sv data can constrain the shear wave vertical velocity vs0 and the depth scale of vti models for homogeneous media the residual moveout of horizontal sv events on image gathers is close to hyperbolic and depends just on the nmo velocity vnmo out to offset to depth ratios of about 1 7 because vnmo differs from vs0 flattening moderate spread gathers of sv waves does not ensure the correct depth of the migrated events the residual moveout rapidly becomes nonhyperbolic as the offset to depth ratio approaches two with the migrated depths at long offsets strongly influenced by the sv wave anisotropy parameter although the combination of vnmo and is sufficient to constrain the vertical velocity vs0 and reflector depth the tradeoff between and the thomsen

paleoenvironmental interpretation based on macro and microstructure analysis of pleistocene slope covers a case study from the miechow upland poland abstract the purpose of the research was to provide a paleoenvironmental reconstruction of the origin of periglacial slope covers in the miechow upland in southern poland the investigated site produced data for the analysis of loess fossil soils cryogenic structures as well as slope deposits complementary sedimentological and soil analyses served as the basis of the research in addition to macroscopic research micromorphological methods were used in the study grain size analysis was also performed finally the content of caco 3 fe 2 co 3 and c org was assessed the research produced a sequence of paleoenvironmental conditions which were then compared with dated loess profiles from western and central europe and russia it was noted that the sequence of paleoenvironmental conditions determined in this study matched that previously identified for the european loess belt including the period from the eemian interglacial to the end of the weichselian glaciation the research results are a contribution to the discussion of the paleoenvironmental significance of loess fossil soils cryogenic structures and slope deposits in addition research has shown that micromorphological analysis is a valuable research tool in soil science and sedimentology

self organization of sorted patterned ground striking circular labyrinthine polygonal and striped patterns of stones and soil self organize in many polar and high alpine environments these forms emerge because freeze thaw cycles drive an interplay between two feedback mechanisms first formation of ice lenses in freezing soil sorts stones and soil by displacing soil toward soil rich domains and stones toward stone rich domains second stones are transported along the axis of elongate stone domains which are squeezed and confined as freezing soil domains expand in a numerical model implementing these feedbacks circles labyrinths and islands form when sorting dominates polygonal networks form when stone domain squeezing and confinement dominate and stripes form as hillslope gradient is increased

application of refraction seismics in alpine permafrost studies a review abstract refraction seismics is a common geophysical application to investigate permafrost in alpine studies this study reviews the physical basis of the use of refractions seismics and introduces the history of its application in alpine environments seismic properties are influenced by rock or soil properties and fluid or ice effects in laboratory measurements these influences are determined and linked to mechanical properties or used for calibration of field studies in field conditions supplementary environmental factors influence the seismic properties of landforms in this paper laboratory studies of rocks from different lithologies and with different properties as well as case studies on rock glaciers moraines talus slopes and debris covered slopes are collected and influencing factors quantitatively analyzed the data demonstrate how lithology porosity and anisotropy influence p wave velocity environmental factors result in a high variation of p wave velocities in landforms however p wave velocities enable the differentiation of active layer and permafrost in rock glaciers and moraines in talus slopes and debris covered slopes p wave velocity contrasts between active layer and permafrost layer might be insufficient and require the application of additional methods for a final differentiation

characterisation and prediction of thickness and material properties of periglacial cover beds tharandter wald germany abstract soils of central european subdued mountain ranges are structured by various layers of relic periglacial slope deposits pleistocene cover beds these have great impact on subsurface substrate properties therefore gaining extensive spatial information on material composition and thickness of slope deposits is essential here we present a gis supported approach to predict layer properties which goes beyond existing deterministic procedures in a section of the tharandter wald saxony germany we deduced subsurface structures from soil pits and auger cores substrates were analysed to clarify stratigraphical setting and relation to parent rock types we assume cryoturbation solifluction slope wash and aeolian sediment admixture to be important processes of periglacial cover bed formation these processes are mainly controlled by geological and geomorphological factors combining assumptions and field data we determine properties of periglacial cover beds based on relief parameters an integrated data set is generated which provides information for a geostatistical interpolation of measured layer thicknesses the composition of solifluidally dislocated substrate is approximated by a modified flow model modelling returned thicknesses of loess bearing layers i e upper layer and intermediate layer prediction of the upper layer involved an inverse distance weighted approach and yielded an inaccuracy of

computation of mars transfer functions for nutations tides and surface loading abstract mars transfer functions for nutations tides and surface loading are computed for different models in order to study the influence of the physics of the interior on the planet s response to external forcing if the core is liquid there is a resonance at the free core nutation fcn period which must be taken into account the fcn period depends on the density of the core and consequently on the density jump at the core mantle boundary cmb and on the dimensions of the core the responses of mars forced by the solar gravitational attraction involve frequencies which could be very close to the fcn the observation of their amplitudes can in that case give us information about whether the core is liquid or not about its dimensions as well as about the density jump at the cmb we therefore consider several models for the interior structure of mars involving different normal mode frequencies and compute the transfer functions for nutations tides and loading as a function of the forcing frequency we show that the amplitudes of the semi annual tri annual and quadri annual nutations could be amplified by several ten percent or even several hundred percent by the fcn resonance depending on the fcn eigenfrequency value here annual means one martian year the same holds for the second degree diurnal tides and loading effects the impact of the core radius density and state on the body and load love numbers is analysed body and low degree load love numbers h and k can change by up to 25 for variations in the core radius of 200 km or for a change in the core state liquid solid the corresponding variations in the tidal gravimetric factor and the loading green s function are about 10 times smaller high degree load love numbers are more sensitive to the upper mantle rheology

martian precession and rotation from viking lander range data the spatial orientation of the martian pole of rotation and axial rotation parameters have been determined at a midpoint in the viking epoch january 1 1980 the mean obliquity e and node angles are e 25 1894 0 0001 35 4796 0 0002 2 the mean precession rate is o 7 83 0 30 arc sec yr 1 the corresponding moment estimate is c mre2 0 355 0 015 and covers two extreme theoretical estimates seasonal annual and semiannual variations in mars rotation angle have also been observed and are 279 100 and 311 100 milliarc second of angle mas respectively after correcting for a general relativity effect a simple model has been constructed for the main contribution involving seasonal mass exchange between the ice caps and atmosphere where the air pressure at the viking 1 lander site is a proxy for the global ice cap air pressure histories the annual term is about 190 mas smaller and differs in phase by 30 compared to the model prediction the semiannual term is 100 mas larger and also differs in phase by 30 compared to the model a combination of tidally driven rotation changes zonal winds polar motion and ice cap model deficiencies may account for any discrepancy the upcoming pathfinder lander and mars global surveyor missions carry ranging transponders which can dramatically improve our knowledge of mars interior through precise determination of the precession rate and detection of core and tidal effects we advocate that plans be developed for a coordinated campaign of simultaneous ranging and doppler tracking to each transponder

pleistocene holocene cover beds on granite regolith as parent material for podzols an example from the sudeten mountains abstract pleistocene periglacial cover beds have been considered to be the proper parent material of soils in the medium mountains of the central europe and in other areas influenced by the periglacial conditions the concept highlights an importance of solifluction and cryoturbation phenomena and an addition of aeolian silt loess in the formation of cover beds significant loess admixture may however hinder podzolization process the objective of the present study was to recognize the stratification of slope materials in the upper zone 1000 1200 m asl of the sudeten mts sw poland and its relation to the morphology and properties of podzols mineralogical and submicromorphological analyzes confirmed autochthonous origin of the parent materials and excluded loess admixture macro and micro observations proved periglacial formation of deeper beds while the pollen analysis confirmed the holocene age of an uppermost sand layer finally four partial mineral sequences were distinguished in soil profiles 1 an underlying granite regolith not always present within the standard soil pit 2 a basal periglacial layer formed by solifluction 3 a cryoturbated transitional zone instead of typical intermediate periglacial layer 4 an uppermost sandy or a sandy silty layer instead of the upper periglacial layer modification of periglacial cover bed series by replacing of the silty upper periglacial layer with sandy holocene cover allowed podzol formation under favorable climate conditions the same palynological and micromorphological observations confirmed polygenetic nature of podzols the present day bh horizon is in fact a humus layer of a late pleistocene early holocene brown earth buried under a sandy cover an albic horizon thickness and its lower boundary are therefore related to the lithological discontinuity in the cover bed series

solifluction rates processes and landforms a global review abstract field data on the rates of solifluction and associated parameters are compiled from the literature in an attempt to evaluate factors controlling the spatial variability in solifluction processes and landforms with special attention on the climate solifluction relationship the analyzed data originate from 46 sites over a wide range of periglacial environments from antarctic nunataks to tropical high mountains solifluction broadly defined as slow mass wasting resulting from freeze thaw action in fine textured soils involves several components needle ice creep and diurnal frost creep originating from diurnal freeze thaw action annual frost creep gelifluction and plug like flow originating from annual freeze thaw action and retrograde movement caused by soil cohesion the depth and thickness of ice lenses and freeze thaw frequency are the major controls on the spatial variation in solifluction processes near the warm margin of the solifluction affected environment diurnal freeze thaw action induces shallow but relatively rapid movement of a superficial layer 5 10 cm thick on average often creating the thin stone banked lobes typically seen on tropical high mountains in addition to diurnal movement annual frost creep and gelifluction may occur on slopes with soil climates of seasonal frost to warm permafrost dislocating a soil layer shallower than 60 cm at a rate of centimeters per year and eventually producing medium size solifluction lobes in high arctic cold permafrost regions two sided freezing can induce plug like flow of a soil mass 60 cm or thicker the correlation between process and landform suggests that the riser height of lobes is indicative of the maximum depth of movement and prevailing freeze thaw type climate change may result in new different ground freezing conditions thereby influencing the surface velocity and maximum depth of soil movement soil moisture and topography also control solifluction high moisture availability in the seasonal freezing period enhances diurnal freeze thaw action and subsequent seasonal frost heaving the latter contributes to raising the moisture content of the thawed layer and promotes gelifluction during the thawing period the slope angle defines the upper limit of the surface velocity of solifluction a diagram correlating the potential frost creep with the actual surface velocity permits an inter site comparison of the relative magnitude of solifluction components physically based modelling of periglacial slope evolution requires synthetic and more detailed field monitoring and laboratory simulations of solifluction processes

soil creep the driving factors evidence and significance for biogeomorphic and pedogenic domains and systems a critical literature review abstract soil and regolith creep have been analyzed for at least the last 140 years using many methodological configurations and temporal and spatial scales the general concept of creeping soil and its mechanism first proposed by w m davis and g k gilbert at the end of the 19th century evolved since the 1940s towards theoretical models and precise short and long term field measurements this fruitful epoch continued with results enhanced at the turn of the 20th century by the application of new research methods e g radiometry and a redefinition of the term soil creep to encompass the sum of stochastic shallow subsurface and near surface processes causing net downslope movement of soil or regolith simultaneously another possibility of creep detection was noticed in dendrochronology and since the 1970s in the formally defined discipline of dendrogeomorphology indirect evaluations of creep activity were performed based on tree ring analyses of bent trees this method found many followers but was also heavily criticized as imprecise and lacking in evidence of which kind of tree trunk curvature e g pistol butt like deformation s shape curvature could be ascribed to creep movement from the beginning soil creep was associated with the activity of living organisms on hillslopes however this aspect of creep studies has never been fully developed in spite of the solid foundations and directions of potential studies pointed out by charles darwin at the end of the 19th century in this paper we focus on the historical context of soil creep studies and highlight forest ecosystems as probably the most active environment of biogenic creep mainly due to tree uprooting and other biomechanical effects of living and dead trees root channel infilling tree root mounding etc that are a factors in biotransport in the final sections the position of biogenic creep in the structure of biogeomorphic systems is discussed in relation to such important conceptual frameworks as the biogeomorphic ecosystem biogeomorphic feedback window and ecosystem engineering we also describe several hypotheses that should be carefully tested in the future and propose several research methods that have the ability to further our knowledge about soil creep radiometry laser scanning and soil micromorphology

the interior structure of mars implications from snc meteorites two end member models of mars present interior structure are presented the first model is optimized to satisfy the geochemical data derived from the snc meteorites in terms of the bulk chondritic ratio fe si 1 71 while the second model is optimized to satisfy the most probable maximum value c 0 366 x m p r p 2 of the polar moment of inertia factor hydrostatic equilibrium and stationary heat transfer are assumed and the basic differential equations for the mechanical and thermal structure are solved numerically together with an isothermal murnaghan birch type equation of state truncated in eulerian strain at forth order we obtain the radial distribution of mass hydrostatic pressure gravity temperature and heat flow density along with the corresponding density stratification viscosity profiles and the global seismic velocity structure of model mars the first model being consistent with the geochemical requirement produces c 0 357 x m p r p 2 whereas the second model commensurate with the geophysical constraint gives fe si 1 35 the calculated central pressure is about 40 gpa in both models and the central temperature is in the 2000 to 2200 k range the model calculations suggest a fe ni fes core a little less than one half of the planetary radius in size surrounded by a silicate mantle subdivided into lower spinel and upper olivine layers and overlain by a 100 to 250 km thick basaltic crust and a surface heatflow density of 25 to 30 mw m 2 in both models the pressure in the mantle is not sufficient for the spinel to perovskite transition to occur the present thermal lithosphere is estimated to be about 500 km thick and to be subdivided into a 300 km thick outermost rheological lithosphere and an underlying thermal boundary layer of mantle convection given the core sulfur content of 14 wt as derived from snc meteorites the martian core is found to be entirely molten implying the nonoperation of a self sustained dynamo due to the absence of sufficiently vigorous convection

up in the refrigerator geomorphic response to periglacial environments in the upper mississippi river basin usa abstract james c knox was best known for his work on holocene and historical changes in fluvial systems but he also had a long standing interest in the effects of late pleistocene periglacial environments on landscape evolution in parts of the upper mississippi river basin that were just outside the laurentide ice sheet margin or as knox put it up in the refrigerator knox and others in the quaternary community of the midwestern u s often suggested that hillslope erosion was accelerated under periglacial conditions so that glacial periods have had a dominant effect on the landscape we see today this paper reviews the evidence and reasoning supporting that view in a study area of the upper mississippi basin bordered on three sides by ice margins of the last glaciation including the wisconsin driftless area and adjacent landscapes sparse but compelling paleoecological data and relict ice or sand wedge polygons provide clear evidence for a cold climate and widespread permafrost around the peak of the last glaciation in highly dissected relatively high relief parts of the study area the loess and soil stratigraphy on ridgetops and the colluvial mantles on steeper slopes are best explained by highly effective hillslope erosion including solifluction during and just after the last glacial maximum knox used the post depositional truncation of a loess unit to quantify contrasting late pleistocene and holocene sediment yields from a small driftless area watershed while the late pleistocene yield indicates accelerated erosion it is still lower than modern sediment yields in many tectonically active or semiarid landscapes and it may reflect deposition of highly erodible loess as well as effects of periglacial conditions the views of knox and other midwestern geomorphologists on landscape evolution through glacial interglacial cycles were highly influenced by the work of robert v ruhe ruhe proposed that an episode of widespread erosion during and just after the last glacial maximum can explain enigmatic aspects of quaternary stratigraphy and the soil landscape on the iowan erosion surface a very low relief landscape of the study area ruhe s key evidence is still valid though it needs to be separated from an implausible model of landscape evolution interpretation of the iowan erosion surface and other low relief landscapes just outside the ice margin also requires recognition of the profound effect of eolian processes on those landscapes under periglacial conditions many new insights on landscape evolution in the study area could result from wider application of cosmogenic nuclide based methods to assess glacial interglacial changes in basinwide rates of erosion and residence time of soils just as important a need exists for much more field based characterization of hillslope fluvial and eolian sediments for comparison with those of modern permafrost regions and past periglacial environments in europe

hydrostatic interfaces in bodies with nonhydrostatic lithospheres below the lithospheres of the terrestrial planets dwarf planets and moons density interfaces adjust over geologic time to align with surfaces of constant gravitational potential it is well known that the shape of such hydrostatic surfaces is controlled by the pseudo rotational potential tidal potential and the induced potential of nonspherical density interfaces in the body when a lithosphere is present however additional gravitational terms must be considered that arise from for example surface relief and crustal thickness variations a first order formalism is presented for calculating the shape of hydrostatic density interfaces beneath the lithosphere when the gravity field and surface shape of the body are known using an arbitrary discretized density profile the shapes are obtained by solving a simple matrix equation as examples lithospheric gravity anomalies account for about 10 of the relief along hydrostatic interfaces in mars whereas for the moon the lithospheric gravity is the dominant contributor to the core shape spherical harmonic degree 1 mass anomalies in the lithosphere generate degree 1 relief along the core mantle boundary and for mars and the moon the core is offset from the center of mass of the body by about 90 m the moments of inertia of the core of these bodies are also misaligned with respect to the principal moments of the entire body an improved crustal thickness map of mars is constructed that accounts for gravity anomalies beneath the lithosphere and the consequences of core relief on the martian free core nutation are quantified plain language summary the shapes of the solid planets and moons are largely hydrostatic and are determined by their rotation rate if the body has gravity anomalies that arise from within a rigid lithosphere these will act to perturb the shape of hydrostatic density interfaces beneath the lithosphere such as the core mantle boundary we present a method to compute the shape of density interfaces beneath the lithosphere when the gravity field of the body is known as examples of our technique we compute the shape of the core mantle boundary for mars and the moon both of which are shown to have important contributions that arise from the lithosphere we also generate a new crustal thickness map that accounts for gravity anomalies generated beneath the lithosphere

climate and material controls on periglacial soil processes toward improving periglacial climate indicators one of the distinguished efforts of a l washburn was to reconstruct mean annual air temperature using periglacial features as climate indicators this paper reviews existing periglacial indicators and proposes a strategy to improve their thermal resolution based on recent periglacial process studies with a focus on solifluction and thermal contraction cracking and associated landforms structures landforms resulting from solifluction reflect both the depth subjected to freeze thaw and the thickness of frost susceptible soils the thickness of a solifluction structure can be used to infer the dominant freeze thaw regime and minimum seasonal frost depth ice wedge pseudomorphs have limited potential as a climate indicator because 1 they mainly reflect extreme winter temperatures 2 their thermal thresholds depend on the host material and 3 they need to be distinguished from frost wedges of other origin produced under different thermal and or material conditions monitoring studies of currently active ice wedges suggest that ice wedge cracking requires a combination of low temperature and large temperature gradients in the frozen active layer further field monitoring of periglacial processes and their controlling factors under various climate conditions and in various materials are needed however to improve the resolution of periglacial paleoclimate indicators

deformation of debris ice mixtures mixtures of rock debris and ice are common in high latitude and high altitude environments and are thought to be widespread elsewhere in our solar system in the form of permafrost soils glaciers and rock glaciers these debris ice mixtures are often not static but slide and creep generating many of the landforms and landscapes associated with the cryosphere in this review a broad range of field observations theory and experimental work relevant to the mechanical interactions between ice and rock debris are evaluated with emphasis on the temperature and stress regimes common in terrestrial surface and near surface environments the first order variables governing the deformation of debris ice mixtures in these environments are debris concentration particle size temperature solute concentration salinity and stress a key observation from prior studies consistent with expectations is that debris ice mixtures are usually more resistant to deformation at low temperatures than their pure end member components however at temperatures closer to melting the growth of unfrozen water films at ice particle interfaces begins to reduce the strengthening effect and can even lead to profound weakening using existing quantitative relationships from theoretical and experimental work in permafrost engineering ice mechanics and glaciology combined with theory adapted from metallurgy and materials science a simple constitutive framework is assembled that is capable of capturing most of the observed dynamics this framework highlights the competition between the role of debris in impeding ice creep and the mitigating effects of unfrozen water at debris ice interfaces

measurement of solifluction rates using multi temporal aerial photography a new method is presented to assess decadal solifluction lobe movement and volumetric changes at the catchmentscale the method is based on photogrammetrical analysis of orthorectified repeat aeria

active boulder movement at high martian latitudes lobate stony landforms occur on steep slopes at high latitudes on mars we demonstrate active boulder movement at seven such sites submeter scale boulders frequently move distances of a few meters the movement is concentrated in the vicinity of the lobate landforms but also occurs on other slopes this provides evidence for a newly discovered common style of activity on mars which may play an important role in slope degradation it also opens the possibility that the lobate features are currently forming in the absence of significant volumes of liquid water

seasonal dynamics of a permafrost landscape adventdalen svalbard investigated by insar abstract nordenskiold land in central spitsbergen svalbard is characterized as a high latitude high relief periglacial landscape with permafrost occurring both in mountains and lowlands freezing and thawing of the active layer causes seasonal frost heave and thaw subsidence while permafrost related mass wasting processes induce downslope ground displacements on valley sides displacement rate varies spatially and temporally depending on environmental factors in our study we apply satellite synthetic aperture radar interferometry insar to investigate the magnitude spatial distribution and timing of seasonal ground displacements in and around adventdalen using terrasar x stripmap mode 2009 2017 and sentinel 1 interferometric wide swath mode 2015 2017 sar images first we show that insar results from both sensors highlight consistent patterns and provide a comprehensive overview of the distribution of displacement rates secondly two dimensional 2d terrasar x insar results from combined ascending and descending geometries document the spatial variability of the vertical and east west horizontal displacement rates for an average of nine thawing seasons the remote sensing results are compared to a simplified geomorphological map enabling the identification of specific magnitudes and orientations of displacements for 14 selected geomorphological units finally june to december 2017 6 day sampling interval sentinel 1 time series was retrieved and compared to active layer ground temperatures from two boreholes the timing of the subsidence and heave detected by insar matches the thawing and freeze back periods measured by in situ sensors our results highlight the value of insar to obtain landscape scale knowledge about the seasonal dynamics of complex periglacial environments

rock glaciers in the northern japanese alps palaeoenvironmental implications since the late glacial in order to determine the palaeoclimatic and palaeo permafrost conditions in the northern japanese alps in central japan the ages of rock glaciers were investigated by relative age dating techniques such as weathering rind thickness and schmidt hammer measurements the results of the relative age dating suggest that the formation of the investigated rock glaciers may have started during the early phase of the late glacial or around the onset of the holocene the lower limit of current discontinuous permafrost in the northern japanese alps which is indicated by the terminus of the lowest active inactive rock glacier lies at 2530 m a s l while that of discontinuous permafrost during the late glacial or early phase of the holocene which is indicated by the terminus of the lowest relict rock glacier lies at 2220 m a s l therefore the lower limit of discontinuous permafrost during these periods would have been at least about 300 m lower than that of the current discontinuous permafrost climatic and geomorphological conditions during the late glacial led to a change in the environment from a glacial environment to a periglacial permafrost environment in the current alpine zone of the northern japanese alps a large number of cirques were deglaciated and several of them were occupied by active rock glaciers around the onset of the holocene copyright 2005 john wiley sons ltd

physical modelling of gelifluction and frost creep some results of a large scale laboratory experiment an experimental slope was constructed in a 5 m 5 m square refrigerated tank the slope was formed of four sections each consisting of regolith soil collected from a distinct bedrock lithology the four lithologies utilized were granite limestone mudstone and slate the slope was subjected to freezing and thawing from the surface downwards water was supplied at the base of the soil during freezing frost heaving and surface downslope soil movement were determined after each of 15 freezing cycles and the profiles of soil movement with depth for each soil type were measured at the end of the 15th cycle the experimental soils were non cohesive those derived from granite and limestone were respectively sandy and gravelly in texture while those derived from mudstone and slate were silt rich mass movement in the granite and limestone soils was due mainly to frost creep and was associated with the growth of needle ice in the mudstone and slate soils gelifluction was dominant as a result of high moisture contents caused by the melting of segregation ice mean per cycle rates of downslope soil transport for the granite limestone mudstone and slate soils were 5 8 cm3 cm 1 6 9 cm3 cm 1 21 2 cm3 cm 1 and 31 2 cm3 cm 1 respectively units referring to the volume of soil passing a unit width of slope per cycle mass movement rates were shown to be strongly related to the silt content of the soils

oxygen isotope stage 3 fluvial and eolian successions in europe compared with climate model results abstract fluvial and eolian successions of oxygen isotope stage 3 are compared with global gcm and regional climate rcm modeling experiments of the stage 3 and last glacial maximum climate in europe differences in precipitation between stage 3 stades and interstades were minor which is confirmed by the fluvial successions the fluvial response to climate variation is non uniform and in southern europe more pronounced than in northern europe the model simulations indicate a strong western winter circulation over europe during stage 3 which is supported by the eolian deposits data wind speeds in the last glacial maximum simulation appear modest compared with those of stage 3 which contrasts with the abundance of eolian deposits this suggests that during glacial climates the stabilizing effect of vegetation determines eolian sedimentation rates rather than wind speed stage 3 can be divided into an older part 45 000 cal yr b p with a relatively stable landscape and moist climate and a younger part with more frequent climate change and decreasing landscape stability