slow but not fast global expansion may explain the surface dichotomy of earth abstract various fast and slow earth expansion hypotheses are reviewed principal objectives are 1 1 to aid geologists to overcome their current mysticism in rejecting accepting or sympathising with earth expansion hypotheses without distinction and 2 2 to stimulate geophysicists into taking full account of the possibility that slow earth expansion by core mantle interaction may have occurred inward migration of the core mantle boundary due to the differentiation and progressive solidification of the liquid outer core might have caused expansion of the earth s radius at a slow mean rate of 0 5 mm a 1 a slowly expanding earth is attractive since it could explain why two distinct types of lithosphere exist oceanic and continental

reading the climate record of the martian polar layered deposits abstract the martian polar regions have layered deposits of ice and dust the stratigraphy of these deposits is exposed within scarps and trough walls and is thought to have formed due to climate variations in the past insolation has varied significantly over time and caused dramatic changes in climate but it has remained unclear whether insolation variations could be linked to the stratigraphic record we present a model of layer formation based on physical processes that expresses polar deposition rates of ice and dust in terms of insolation in this model layer formation is controlled by the insolation record and dust rich layers form by two mechanisms 1 increased summer sublimation during high obliquity and 2 variations in the polar deposition of dust modulated by obliquity variations the model is simple yet physically plausible and allows for investigations of the climate control of the polar layered deposits pld we compare the model to a stratigraphic column obtained from the north polar layered deposits npld fishbaugh k e hvidberg c s byrne s russel p s herkenhoff k e winstrup m kirk r 2010a geophys res lett 37 l07201 and show that the model can be tuned to reproduce complex layer sequences the comparison with observations cannot uniquely constrain the pld chronology and it is limited by our interpretation of the observed stratigraphic column as a proxy for npld composition we identified however a set of parameters that provides a chronology of the npld tied to the insolation record and consistently explains layer formation in accordance with observations of npld stratigraphy this model dates the top 500 m of the npld back to 1 million years with an average net deposition rate of ice and dust of 0 55 mm a 1 the model stratigraphy contains a quasi periodic 30 m cycle similar to a previously suggested cycle in brightness profiles from the npld laskar j levrard b mustard f 2002 nature 419 375 377 milkovich s head j w 2005 j geophys res 110 but here related to half of the obliquity cycles of 120 and 99 kyr and resulting from a combination of the two layer formation mechanisms further investigations of the non linear insolation control of pld formation should consider data from other geographical locations and include radar data and other stratigraphic datasets that can constrain the composition and stratigraphy of the npld layers

a multidisciplinary approach for sustainable management of a complex coastal plain the case of sibari plain southern italy abstract coastal plain environments constantly adapt to change as a result of natural processes and increasing anthropogenic pressure as in the case of the low relief sibari coastal plain calabria southern italy in order to reconstruct the hydrostratigraphic framework and explain the spatial distribution of groundwater salinization of the sibari coastal plain an integrated hydrogeological and geochemical approach was applied to support an accurate conceptualisation and modelling of the whole plain groundwater system litho hydro stratigraphic relationships were constructed from lithologic logs obtained from exploratory boreholes whereas the groundwater flow system has been studied using conventional hydrogeological field investigations hydrochemistry and isotope hydrology three distinct hydrological units hu3 shallow aquifer hu2 aquitard and hu1 lower aquifer were identified showing distinct geometrical hydrochemical and isotopic signatures with the aim of explain the origin of na cl ca cl and na hco 3 waters were considered the role of ion exchange processes the results demonstrate that values of na mg 2 cl and so 4 can be attributed to seawater intrusion where k is probably the major pollutant of the shallow aquifer the adopted multidisciplinary approach provides an effective tool for accurately determination of groundwater processes and can be useful for a sustainable management of water resources in coastal plain the physically based model of the pail groundwater system was able to explain the observed groundwater salinity variations and to support a detailed long lasting numerical simulation of variations in the quantity and quality of groundwater resources

mars residual north polar cap earth based spectroscopic confirmation of water ice as a major constituent and evidence for hydrated minerals a new reflectance spectrum of the martian north polar cap is analyzed and it shows water ice absorption features this evidence confirms the result of the viking irtm and mawd experiments which indicate that the north residual polar cap of mars is composed of water ice during the season observed northern hemisphere spring ls 50 the spectra presented here show that other materials are probably present as well these other materials may be hydrated minerals as indicated by weak absorptions in the spectrum at 1 9 2 3 and possibly 1 4 m but the materials seem to be otherwise spectrally bland

regional uplift and local tectonic deformation recorded by the quaternary marine terraces on the ionian coast of northern calabria southern italy abstract the setting of a flight of marine terraces along a 65 km long section of the ionian coast of northern calabria is the result of the interaction between interglacial sea levels regional uplift and local fault related elevation changes seven terraces with corresponding palaeoshoreline angles at elevations ranging from 12 m to 420 m were recognised by aerial photo interpretation and field surveying the terraces were correlated to the oxygen isotope stages 1 5a 5c 5e 7 9 15 which correspond to the 7 81 102 124 215 330 and 600 ka highstands of the palaeosea level curve the 600 ka long regional ascent of the terraces took place at an average uplift rate of 0 67 mm yr this value slightly but progressively increases southward along the coastline the elevation of the strandlines is related to the activity of tectonic structures three cases were analysed allowing us 1 to recognise the height anomalies of the terraces on the sibari plain as the result of cumulated coseismic deformation caused by the normal castrovillari fault and on this basis calculate a minimum slip rate and a mean recurrence time for a single event of deformation 2 to exclude the presence of significant vertical deformations and consequently activity on the easternmost section of the normal pollino fault and 3 to hypothesise the presence of an hitherto unknown active fault responsible for the strong vertical displacements of the flight of terraces near the river avena finally we find the ratio of the rate of regional uplift to the average rates of local tectonic deformation to be 2 to 3 1

late quaternary stratigraphic setting of the sibari plain southern italy hydrogeological implications abstract the aim of this study is the reconstruction of the late pleistocene holocene stratigraphy of the sibari plain southern italy aimed to obtain information about hydrogeological framework a multidisciplinary approach combining boreholes data and electrical resistivity tomography allowed us to recognize three electro stratigraphic units which consist of upper pleistocene fluvial and floodplain littoral facies deep aquifer passing upward to holocene marine transitional deposits aquiclude evolving toward continental sediments shallow aquifer related to the crati delta progradation the late quaternary holocene plain evolution took place in a tectonic controlled setting and was driven by the interaction between sea level variations and local factors the presence of a ne sw fault zone controlled the facies and thickness of holocene sediments along strike of the fault this active fault zone contributed to determine the plain stratigraphic architecture the arrangement of the depositional environments and consequently the stratigraphic pattern

rheology of ices a key to the tectonics of the ice moons of jupiter and saturn the polymorphic varieties of water ice are important rock forming minerals in the outer solar system the voyager 1 and 2 missions have shown that most of the ice moons of jupiter and saturn have had some form of tectonic or internal activity understanding of the tectonics and building reasonable models of the interior of these planets depend on our knowledge of the theological properties and viscosity of high pressure and low temperature forms of ice

discrimination of soil erosion and fluvial sediment areas a computer model has been used to estimate potential sheet and rill erosion and delivered sediment from field sized areas of five selected agricultural watersheds consideration of these estimates in relation to defined tolerance levels of soil erosion and sediment yield has resulted in the mapping of 1 areas that exhibit erosion problems and serve as sediment sources 2 areas that exhibit only erosion problems but do not act as sediment sources 3 areas that serve only as sediment sources but do not exhibit erosion problems and 4 areas that have no significant erosion problems or sediment sources a simple approach has been developed for the preparation of such maps on the basis of a limited data base involving factors affecting erosion and fluvial sedimentation this relatively simple yet accurate technique offers agricultural and conservation extension personnel a method for the identification of soil erosion problem areas and or sediment sources author

convection experiments in high prandtl number silicones part 1 rheology equipment nomograms and dynamic scaling of stress and temperature dependent convection in a centrifuge it has been impossible to model mantle convection by other than numerical methods because dynamically scaled laboratory experiments of practical size in high prandtl number fluids would require a temperature gradient reaching far above the sublimation temperature of any known fluid however convection can be established in high prandtl number fluids without large temperature gradients and length scales if the thermal buoyancy forces are enhanced by increasing the gravitational acceleration this has been realized by placing the test tank in a high speed centrifuge up to 3000 rpm at the hans ramberg tectonic laboratory uppsala the centrifugal acceleration imposes an apparent gravity field several thousand times the earth s gravity by using this method supercritical rayleigh numbers up to 106 can be achieved in a transparent polymer fluid sgm36 of prandtl number 108 the carefully developed test tank and control unit and a rigorous derivation of the conditions for dynamic similarity of convection in fluids with temperature and stress dependent rheology facilitates detailed laboratory studies of high prandtl number convection the working philosophy section 2 equipment section 3 non newtonian and temperature dependent scaling procedure section 4 and practical nomograms section 5 are presented here to aid such laboratory studies the significance of this new laboratory method for studying convection is outlined in section 6 real convection experiments in high viscosity polydimethylsiloxanes now have the potential to contribute to the understanding of six major aspects of convection these are 1 1 progressive deformation and displacement in three dimensional convective flow fields 2 2 convective mixing 3 3 convection with high prandtl numbers 4 4 non newtonian flow 5 5 temperature dependent flow and 6 6 high rayleigh number convection detailed applications will be discussed in a companion paper part 2 of the present project

polar margin dunes and winds on mars the approximately concentric arrangement of layered deposits and dune fields at the two martian poles may reflect a nearly steady state dispersal of material from the polar deposits data on effective surface winds from high resolution viking images combined with theory of local winds suggest that the northern dunes are in part confined to a latitude band by winds generated by their own low albedo dispersal of the dark sand from the southern polar region is not subject to this kind of feedback because the irregular topography prevents areal accumulations sufficiently extensive to produce winds

dust and ice deposition in the martian geologic record abstract the polar layered deposits of mars demonstrate that thick accumulations of dust and ice deposits can develop on the planet if environmental conditions are favorable these deposits appear to be hundreds of millions of years old and other deposits of similar size but of greater age in nonpolar regions may have formed by similar processes possible relict dust deposits include from oldest to youngest noachian intercrater materials including arabia mantle deposits noachian to early hesperian south polar pitted deposits early hesperian hellas and argyre basin deposits late hesperian electris deposits and the amazonian medusae fossae formation these deposits typically are hundreds of meters to a couple kilometers thick and cover upward of a million or more square kilometers the apparent persistence of dust sedimentation at the south pole back to the early hesperian or earlier and the early growth of tharsis during the late noachian and perhaps earlier indicates that extensive polar wandering is unlikely following the middle noachian a scenario for the overall history of dust and perhaps ice deposition on mars includes widespread voluminous accumulations perhaps planetwide during the noachian as impacts volcanism and surface processes generated large amounts of dust the arabia deposits may have formed as ice availability and dust accumulation waned during the early hesperian thick dust sedimentation became restricted to the south pole and the deep hellas and argyre basins the north polar sedimentary record prior to the amazonian is largely obscured deposits at electris and medusae fossae may have resulted from local sources of fine grained material perhaps volcanic eruptions

models of climate cycles recorded in martian polar layered deposits abstract layered strata observed in orbital images of polar sedimentary terrains on mars have been hypothesized to contain information about recent variations in the martian climate celestial mechanicians have determined that mars has experienced large amplitude quasi periodic variations in obliquity and eccentricity planetary meteorologists have inferred that the resulting changing patterns of solar heating must have had dramatic effects on martian climate accordingly it might be possible to link the known recent history of orbit axial variations with the physical characteristics of the most recently deposited strate determined from orbital imagery our paper explores that possibility quantitatively for various models of the formation of the polar layered deposits and the layering developed within them we modeled the formation of polar layered deposits during the past 10 my for two general classes of model uniform deposition rate udr models assume that the major constituent of the layered deposits is deposited at a uniform rate and that layering is established by climate induced variations in the concentration of a minor constituent climate modulated deposition rate cmdr models assume that the deposition rate of the major constituent is controlled by climate and that layer boundaries correspond to intervals of nondeposition in both models abrupt changes in deposition regime occur when a function of the orbit axial parameters crosses a threshold value detailed physical mechanisms for the control of sedimentation by orbit axial variations were developed for two specific models of the cmdr type in one model the deposits are assumed to be primarily composed of dust in the other they are assumed to be predominantly water ice we calculated the times at which abrupt changes in deposition regime occur and determined the relative thicknesses of successive layers which can be compared against layer thicknesses made from orbital imagery in all these models obliquity variations exert the dominant influence on the sequential variations in layer thickness although eccentricity and precession index longitude of perihelion may take recognizable contributions as well the layer patterns for the north and south polar deposits are identical for the dust model and only slightly different for the ice model but this is at least partly a consequence of simplifying assumptions the sequential variation in layer thickness is also very sensitive to those model parameters which control the fraction of time for which deposition occurs when the climate threshold for deposition is low deposition occurs a large fraction of the total time and characteristic patterns form with one thick layer and a number of much thinner ones such patterns would be easily recognized in photogeological measurements of layer thickness when the threshold for deposition lies in the mid range with respect to excursions of the climate function deposition occurs approximately half of the time and there is only slight modulation of layer thickness when the threshold for deposition is high deposition occurs only a small fraction of the total time and groups of layers form which are separated form other groups by long periods of nondeposition the stratigraphic unconformities that separate groupings of five to ten layers in the polar deposits may indicate that the martian polar region has experienced such a depositional history the feasibility of using these model results to verify the theory of climate control of polar stratigraphy on mars and to gain additional insights into the significant processes is considered the stratigraphy issues raised here are also explored in the context of recent work on the interpretation of stratigraphy of ocean margins from this comparison there emerge some valuable insights into the stratigraphic effects of periods of nondeposition and the uncertaintiesin interpreting images of exposed polar strata on mars

a new approach to assessing the burial depth of ground ice deposits and its application to proposed mer landing sites in isidis planitia 1 the recent results by the gamma ray spectrometer instrument on mars odyssey boynton et al 2002 indicate the possibility of ground ice deposits within a few meters of the surface even at low latitudes and midlatitudes the stability of ground ice deposits at these latitudes is a puzzling question to address this question we have developed the berlin mars near surface thermal model bmst a model for the thermal behavior of the martian surface with a special focus on the volatile transport within the subsurface material using the bmst we have performed a case study to derive limits on the burial depth of ground ice deposits stable over annual cycles at the mer landing sites in isidis planitia we have studied the temperature gradient within the subsurface assuming different structures and thermophysical properties for the surface and subsurface material while the results derived here will have no immediate consequences for the mer mission because isidis planitia has been demoted to a backup landing site the results show the potential and versatility of the model we have developed and give some results on the surface properties of isidis planitia

stratigraphic relationships within martian polar cap deposits abstract deposits of layered ice and dust accumulate on the smooth and banded terrains of the north and south polar cap deposits while erosion of equator facing slopes of layered terrain expose these layers banded terrain occurs at exposures of irregular layers resulting from slight erosion of the feather edges of layers deposited on pole facing trough walls these deposits unconformably overlap onto adjacent layered terrain stripping of layers occurs in areas of strong multidirectional wind forming striped terrain local wind scour has also produced steep scarps with crescentic planform often associated with dune fields positioned immediately downwind unconformities are common within layered deposits in areas of complex topography at the north pole these indicate that episodes of deposition of 5 10 layers alternate with slight erosion of pole facing trough walls troughs that strike north south alternate between erosional widening and deepening and depositional infilling creating multiple unconformities troughs near the equatorward limit of polar deposits increase in relief by deposition on adjacent smooth terrain and locally by erosional deepening troughs may migrate poleward replacing the relief increase by depositional infilling when they near the poles

geomorphic expression of active tectonics in a rapidly deforming forearc sila massif calabria southern italy we examine the tectonic geomorphology of la sila calabria southern italy a high standing 1500 m plateau surrounded by crustal extension with map dem and field data these data are used to constrain a simple geodynamic model that describes short wavelength deformation of the plateau rim topographic metrics including drainage patterns river longitudinal profiles and swath profiles are consistent with field stratigraphic relationships collectively suggesting that local tectonic deformation is embedded within a broader regional uplift that has increased the mean elevation of the sila plateau during the quaternary the concavity steepness and length gradient index of modeled river longitudinal profiles proved to be the most useful metrics for recording the effects of locally active faults a previously unrecognized horst on the northeastern portion of the plateau was identified with these data nevertheless the core of the sila plateau remains relatively undeformed with respect to its flanks which are characterized by steep fault bounded escarpments active extension has dropped base level for and unloaded the plateau rim causing deep fluvial incision and associated flexural uplift of the footwall this footwall uplift helps maintain a separate external and nearly radial drainage away from the plateau along its flanks and a nearly closed drainage for the plateau interior a drainage divide roughly correlates with the plateau rim inhibiting the process of drainage integration through the sila interior and subsequent landscape dissection as a result geomorphic processes driving erosion of the sila upland are lagging behind the tectonic processes that have driven rock uplift leading to an overall increase in mean surface elevation these results underscore the importance of the lag times a landscape may endure in transforming from one tectonic and base level condition to another we conclude that the calabrian forearc has a similar geomorphic evolution as the more northern apennines consistent with the emerging view that growth of apennine topography has been recent quaternary rapid and possibly decoupled from rock deformation in the orogenic wedge

onset and migration of spiral troughs on mars revealed by orbital radar the northern polar cap of mars containing enough water to cover the entire planet to a depth of several metres features two major landforms that stand above all others these are the enormous canyon chasma boreale and a series of spiral troughs the processes leading to their formation have remained unclear now two papers in this issue present detailed histories of both systems john holt and colleagues use penetrating radar imagery from mars reconnaissance orbiter s radar sounder to show that depositional processes rather than a catastrophic event formed the chasma boreale isaac smith and john holt use mars reconnaissance orbiter data to rule out erosional cutting of polar ice as the cause of the central troughs and instead conclude that they too are largely depositional having migrated polewards and upwards in elevation in the past two million years a pinwheel array of deep troughs has been one of the most perplexing features of the north polar layered deposits on mars many ideas have been put forward about how it formed but there is as yet no consensus here penetrating radar has been used to rule out erosional cutting as a mechanism for the formation of the array instead it is concluded that the troughs are largely depositional in origin and have migrated to the poles and upwards in elevation over the past two million years or so the landscape of the north polar layered deposits of mars npld is dominated by a pinwheel array of enigmatic spiral troughs1 the troughs have intrigued planetary scientists since the mariner 9 spacecraft returned the first close up image in 1972 but conclusive evidence of their origin has remained elusive debate continues regarding all aspects of the troughs including the possibility that they have migrated2 3 4 5 their age in relation to the current npld surface6 and whether they are fundamentally erosional6 7 or constructional2 4 features the troughs are probably related to climatic processes2 8 yet the nature of this relationship has remained a mystery previous data characterizing only the exposed nlpd surface were insufficient to test these hypotheses here we show that the central spiral troughs initiated after deposition of three quarters of the npld quickly reached a stable morphology and migrated approximately 65 kilometres poleward and 600 metres in altitude over the past two million years or so our radar stratigraphy rules out hypotheses of erosional incision post dating deposition6 7 9 10 and instead largely validates an early hypothesis for constructional trough migration2 3 4 5 with wind transport and atmospheric deposition as dominant processes these results provide hard constraints for palaeo climate models and a new context for evaluating imagery spectral data and now radar sounding data the better to understand the link between orbital parameters and climate the role of climate in shaping the polar ice of mars and eventually the age of the polar deposits themselves8 11 12 13

detrital modes in a late miocene wedge top basin northeastern calabria italy compositional record of wedge top partitioning abstract the composition and stratigraphic relations of sandstones and associated conglomerates derived from erosion of the northern calabrian terranes provide important constraints for paleotectonic and paleogeographic models of the neogene wedge top depozone evolution of the southern italy foreland basin system after onset of continental collision in the southern italy orogenic belt during late oligocene to early miocene the calabrian arc drifted northeastward accreting over the adria lithosphere during mid to late miocene time since the tortonian the northern calabrian terranes represented an uplifted thrust belt in which along its leading edge tectonic subsidence was responsible for accumulation of a thick tortonian to quaternary succession dominantly siliciclastic up to 3300 meters thick deposited in the wedge top depozones rossano and crotone basins sandstone assemblages have a homogeneous quartzofeldspathic composition in the rossano and crotone basins characterized by a compositional trend through time in response to regional tectonics evolution of the basins fill occurred during 1 serravallian tortonian 2 late tortonian to early messinian and 3 late messinian detritus shed into those basins was derived mainly from terranes within the strongly deformed sila mountains allochthon which was one of the principal structural elements of the nearby northern calabrian terranes consisting of hercynian plutons intruding paleozoic cambrian to carboniferous metasedimentary host rocks and locally having a sedimentary cover of mesozoic longobucco group or early miocene paludi unit clastics low to medium grade metamorphic and minor plutonic grain types metamorphiclastic petrofacies represent the main detritus in the earliest serravallian tortonian sedimentation that accompanied progressive flexural bending of the western margin of the foreland basin system tortonian to early messinian time was characterized by isolation of the mediterranean region from the global marine realm leading to evaporite sedimentation in the foreland in addition to intense regional and local tectonics compositional response to those events was a marked increase in sedimentary detritus sedimenticlastic petrofacies related to cannibalization of early messinian evaporite successions after the evaporitic events within the basins and the gradual re establishment to the normal marine conditions sandstone detrital modes are characterized mainly by a return of the serravallian tortonian compositional modes i e metamorphic plutoniclastic petrofacies the post evaporitic sedimentation corresponds to a major tectonic rearrangement on both rossano and crotone basins related to extrusion and inversion of the basal portion of the serravallian tortonian sequences in the intermediate zone to form an intervening ciro structural high in the crotone basin during late messinian deposition of the carvane conglomerate records an abrupt sudden arrival of distinctive sedimentary containing clasts of detritus of reddish limestone marl quartz arenite siltstone and chert derived from mesozoic to tertiary basinal sequences of the southern apennines domains i e sicilide complex terranes detrital mode evolution of the inner portions of the late miocene southern italy foreland basin system was in response to abrupt tectonic partitioning due to continuation of accretionary processes rapid uplift of mid crustal blocks and the superposition of wrench tectonics

core top calibration of δ18o and δ13c of g ruber white and u mediterranea along the southern adriatic coast of italy we carried out an extensive survey of the oxygen and carbon isotope composition of the planktic species g ruber white and of the benthic species u mediterranea along the southern italian coast of the adriatic sea and in the gulf of taranto comparison with seasonal satellite based sea surface temperature maps and water column profiles as well as with several sets of water samples allows estimation of the effect of salinity and different nutrient supply on the 18o and 13c of foraminifera the results indicate that g ruber white while being highly affected by different salinity and nutrient distributions related to circulation patterns of major water masses dominantly record summer temperature conditions u mediterranea reflect the recent environmental conditions such as nutrient supply and bottom water temperature characteristics along the southern italian coast and clearly show the transition from a near coastal eutrophic system to an offshore oligotrophic system

origin of groundwater salinity and hydrogeochemical processes in a confined coastal aquifer case of the rhone delta southern france the rhone delta south of france camargue 750 km2 is a coastal saline wetland located along the mediterranean sea the confined aquifer of this delta shows high values of electrical conductivity rising from the north 4 ms cm to the shoreline 58 ms cm this work aims to identify the origin of groundwater salinity and the geochemical processes occurring in this coastal confined aquifer according to the degree of salinity a natural tracing approach is considered using monthly sampling in 8 piezometers for chemical and isotopic analyses 18o 2h 13ctdic ionic and isotopic ratios demonstrate that strong salinities are due to a simple mixing between mediterranean seawater and freshwater seawater contribution reaches up to 98 at 8 km from the shoreline seawater intrusion induces a particular groundwater chemistry which varies with the degree of seawater contribution 1 in the less saline part of the aquifer seawater contribution 20 the intrusion induces so4 reduction which is confirmed by highly depleted 13ctdic values up to 19 the 13ctdic also reveals that methanogenesis processes may occur in the most reductive part of the aquifer due to so4 reduction the intrusion induces a shift in carbonate equilibrium leading to supersaturation with respect to dolomite and or magnesian calcite thus carbonate precipitation may occur in the area strongly influenced by seawater

first high resolution stratigraphic column of the martian north polar layered deposits 1 this study achieves the first high spatial resolution layer scale measured stratigraphic column of the martian north polar layered deposits using a 1m posting dem the marker beds found throughout the upper north polar layered deposits range in thickness from 1 6 m 16 0 m 1 4 m and 6 of 13 marker beds are separated by 25 35 m thin layer sets have average layer separations of 1 6 m these layer separations may account for the spectral power peaks found in previous brightness profile analyses marker bed layer thicknesses show a weak trend of decreasing thickness with depth that we interpret to potentially be the result of a decreased accumulation rate in the past for those layers however the stratigraphic column reveals that a simple rhythmic or bundled layer sequence is not immediately apparent throughout the column implying that the relationship between polar layer formation and cyclic climate forcing is quite complex

observations of the north polar region of mars from the mars orbiter laser altimeter elevations from the mars orbiter laser altimeter mola have been used to construct a precise topographic map of the martian north polar region the northern ice cap has a maximum elevation of 3 kilometers above its surroundings but lies within a 5 kilometer deep hemispheric depression that is contiguous with the area into which most outflow channels emptied polar cap topography displays evidence of modification by ablation flow and wind and is consistent with a primarily h2o composition correlation of topography with images suggests that the cap was more spatially extensive in the past the cap volume of 1 2 3 10 6 to 1 7 3 10 6 cubic kilometers is about half that of the greenland ice cap clouds observed over the polar cap are likely composed of co 2 that condensed out of the atmosphere during northern hemisphere winter many clouds exhibit dynamical structure likely caused by the interaction of propagating wave fronts with surface topography

internal structure of the martian south polar layered deposits 1 we investigate the three dimensional 3 d stratigraphic structure of the south polar layered deposits spld on mars prominent bench forming layers exposed on spld scarps were observed and mapped in three dimensions using high resolution topographic and imaging data sets using the 3 d location of exposures of one of these strata we can accurately describe the shape of that layer using simple mathematical functions analysis of these functions and the surface topography can be used to reliably predict where on other scarps this layer is exposed in general this bench forming layer and its surrounding strata is not flat and is well approximated as a parabolic dome near the center of the spld its curvature indicates that when deposited it was draped over a topographic dome similar in size to that of the present day the scarps in which this layer is exposed must have formed subsequently and have not been significantly modified by flow processes the basement topography exercises some control over the shape of the interior strata in extreme cases our successful layer fitting technique illustrates the regional uniformity in layer formation and the lack of major internal defects such as faulting within the spld we have mapped exposures of what appear to be this layer in scarps farther from the center of the deposits the position of these exposures can be used to modify the modeled parabolic shape at the periphery of the spld these peripheral elevations provide constraints on the role of flow in the overall shaping of the spld

punishment for the sinner holocene episodic subsidence and steady tectonic motion at ancient sybaris calabria southern italy abstract although the calabria region in southern italy experienced quaternary uplift intense holocene subsidence is documented at ancient sybaris one of the most powerful among the greek colonies collectively known as magna greacia sybaris flourished along the ionian sea coast of north eastern calabria since 2 7 ka bp and until the end of the roman empire when it went progressively concealed below the ground study of the latest pleistocene holocene evolution of this area involved analysis of the relative sea level history for individual borehole logs based on re calibration of published ages and stipulation of nominal sea level positions related to each marker for investigation of the short term evolution a novel compilation of geological and archaeological sea level markers was supported by new radiometric ages appraisal of the position of dated markers when compared to a sea level curve built on purpose for this coast using an updated glacio hydro isostatic model indicates a locally intense difference in vertical motion between boreholes located away from or close to the ancient town specifically whereas data from the basement of the archaeological layers document large subsidence more distant sites behaved differently a site 2 km to the nw of the settlement was apparently stable throughout the holocene and a site 6 km to the se experienced uplift at 1 5 mm y since 0 6 ka bp in addition analysis reveals temporal changes in subsidence pattern in the archaeological area large 5 6 mm y early holocene subsidence at sybaris slowed to 1 5 mm y during the middle part of the holocene the slowing down trend continued during and after historical occupation at 0 8 mm y a value similar to the long term 35 40 ka bp rate established from the deepest borehole samples these data are interpreted as suggesting that sediment compaction affected the basement of sybaris during the early holocene and progressively ceased during historical times when a tectonic signal prevailed during historical time the spatial difference in vertical motion is chiefly attributed to differential growth of nearby folds documented by morpho tectonic studies on land and seismic profiles analysis in the offshore of sybaris whereas location above a syncline caused tectonic subsidence at sybaris the regions to the north and south record stability or uplift that reflects transition to growing anticlines in the short term 1 10 ka scale these local tectonic processes prevail over the regional uplift pattern which is expressed at the 100 ka scale or over

three dimensional structure and origin of a 1 8 km thick ice dome within korolev crater mars korolev is an 80 km diameter impact crater located at 72 7 n 164 5 e containing a large domed deposit perennial water ice is thought to be currently unstable there however using a 3 d analysis of the dome s internal radar stratigraphy we estimate that korolev s central mound contains between 1400 and 3500 km3 of water ice that is up to 1 8 km thick furthermore the stratigraphic structure of this ice dome is strikingly similar to the north polar layered deposits npld on planum boreum approximately 600 km to the north additionally our stratigraphic analysis suggests that korolev ice was not previously part of a once larger polar ice sheet but rather it was deposited locally we conclude that korolev crater s ice likely deposited during the same climate regime as planum boreum s npld but independently this implies that the incorporation of circumpolar ice deposits such as korolev may prove useful in reconstructing a unique mars polar climate history

an ice age recorded in the polar deposits of mars layered ice deposits at the poles of mars record a detailed history of accumulation and erosion related to climate processes radar investigations measure these layers and provide evidence for climate changes such as ice advance and retreat we present a detailed analysis of observational data showing that 87 000 cubic kilometers of ice have accumulated at the poles since the end of the last ice age 370 000 years ago this volume is equivalent to a global layer of 60 centimeters the majority of the material accumulated at the north pole these results provide both a means to understand the accumulation history of the polar deposits as related to orbital milankovitch cycles and constraints for better determination of mars past and future climates

north polar stratigraphy and the paleo erg of mars an accurate self consistent way of coregistering the imaging and topographic data sets of the mars global surveyor mission was developed and used to begin a stratigraphic analysis of the northern polar region a distinct change in the layering style exists at a definite stratigraphic horizon near the base of the north polar layered deposits occurrences of the contact between two distinct layered units can be mapped hundreds of kilometers apart at nearly the same mars orbiter laser altimeter mola elevation the lower layered unit has a consistent association with sand dunes leading to the conclusion that it is an eroding sand rich deposit that predates most of the overlying north polar layered deposits which exhibits the expected features of a dust ice mixture these results suggest that an areally extensive erg was in existence before the present ice cap and that the present circumpolar erg is likely composed of material reworked from this older deposit the volume of this lower unit is estimated to be on the order of 10 5 km 3 the presence of this deposit implies that there existed a period in mars history when there was no icy polar cap a dramatic climatic change leading to the deposition of the upper layered icy unit in the present day polar layered deposits represents a major event in mars history however owing to uncertainties in the mechanics of layered deposits formation such an event cannot be dated at this time

the polar spirals of mars may be due to glacier surges deflected by coriolis forces abstract all previous accounts of the spiral patterns at the martian poles emphasize that the north polar spiral is centered about the geographic pole whereas that of the south polar region is off set by about 4 this paper demonstrates that the patterns near both poles are centered on topographic highs rather than the spin poles themselves this is circumstantial evidence in favour of the relatively unexplored mechanism of radial outflow of viscous rock by gravity spreading the hypothesis developed here is that the spiral patterns are essentially due to crevasse patterns formed perpendicular to flow lines which are perturbed by coriolis forces in order to account for a crevasse pattern that has a form concave to the east the angular deflection of an hypothetical ice flow emanating from the topographic high centered about the geographical north pole must be about 40 or 0 7 radians in a westward direction at 85 n latitude the polar cap rock has previously been assumed to consist mainly of either frozen carbondioxide or water ice corresponding viscosities at 190 k allow for the occurrence of radial outflow or gravity driven tectonics at a maximum rate of 1 cm a 1 but the flow pattern remains unaffected by coriolis forces the spiral patterns of the martian poles can be explained if the flowing mass has an occasional effective kinematic viscosity as low as about 7 10 6 m 2 s 1 because gravity tectonics will then be deflected by coriolis forces resulting in appropriately curved flowlines a tensile fracture pattern resembling an anticlockwise spiral pattern perpendicular to the clockwise deflected flowlines may subsequently form by local brittle failure the occasional kinematic viscosity 7 10 6 m 2 s 1 would cause flow rates of 0 2 m s 1 along the slopes of the topographic highs this velocity and the corresponding viscosity is tentatively thought to be possible when thermal and pressure runaway occurs in the polar layered deposits this would mean glacier surges on the martian poles are two orders of magnitude faster than those hitherto observed on earth

raised coastal terraces along the ionian sea coast of northern calabria italy suggest space and time variability of tectonic uplift rates abstract a detailed study of uplifted middle late pleistocene marine terraces on the eastern side of northern calabria southern italy provides insights into the temporal and spatial scale variability of vertical displacement rates over a time span of 400 ka calabria is located in the frontal orogen of southern italy above the westerly plunging ionian slab and a combination of lithospheric crustal and surface processes concurred to rapid late quaternary uplift eleven terrace orders and a raised holocene beach were mapped up to 480 m a s l and were correlated between the coastal slopes of pollino and sila mountain ranges across the sibari plain facing the ionian sea side of northeastern calabria precise corrections were applied to the measured shoreline angles in order to account for uncertainty in measurement erosion of marine deposits recent debris shedding and bathymetric range of markers radiometric esr and 14 c dating of shells provides a crono stratigraphic scheme although many samples were found to be resedimented in younger terraces terrace t4 whose inner margin stands at elevations of 94 130 m is assigned to mis 5 5 124 ka based on new esr dating and previous amino acid racemization estimations the underlying terraces t3 t2 and t1 are attributed to mis 5 3 100 ka 5 1 80 ka and 3 60 ka as inferred from their relative position supplemented by esr and 14 c age determinations the age of higher terraces is poorly constrained but conceivably is tracked back to mis 11 400 ka the reconstructed depositional sequence of terraces attributed to mis 5 5 and 7 reveals two regressive marine cycles separated by an alluvial fanglomerate which given the steady uplift regime points to minor sub orbital sea level changes during interstadial highstands based on the terrace chronology uplift in the last 400 ka occurred at an average rate of 1 mm a but was characterized by the alternation of more rapid up to 3 5 mm a and slower down to 0 5 mm a periods of displacement spatial variability in uplift rates is recorded by the deformation profile of terraces parallel to the coast which document the growth of local fold structures

the effects of martian orbital variations upon the sublimation and relaxation of north polar troughs and scarps abstract the north polar layered deposits pld of mars are climatologically significant because they represent the largest actively exchanging reservoir of martian water the kilometer scale topography of the north pld is dominated by troughs and scarps which exhibit highly correlated surface slopes and total depths the most widespread theories of pld evolution presume that the asymmetrical nature of north pld troughs characterized by equatorward facing slopes that are generally steeper than poleward facing slopes is the result of preferential h 2 o sublimation from equatorward facing trough walls however our orbitally modulated simulations indicate that there is no long term sublimation advantage of equatorward facing trough walls because of the effects of obliquity upon the slope dependence of sublimation rate in contrast we propose that viscous relaxation of subsurface water is consistent with the slope and depth distributions of north pld troughs and scarps the results of our finite element simulations suggest that a mere 2 k difference in the subsurface temperatures of opposing trough walls is sufficient to produce the observed slope disparity due to the slower rate of uplift of colder poleward facing trough walls both our sublimation and relaxation simulations indicate that present day north pld troughs have formed since 5 ma and are not sites of long term deposition additionally our results imply that glacial flow may govern the large scale evolution of the north pld especially at high obliquity

martian north polar layered deposits stratigraphy implications for accumulation rates and flow 1 we have used mars orbiter camera moc images and mars observer laser altimeter mola data to correlate specific layers within the upper 500 m of the martian north polar layered deposits in many troughs using these correlation results we derive relative accumulation rates across the polar layered deposits and through time we identify two major layer sequences one lying stratigraphically above the other each consistent with an overall curving downward layer structure with shallow slopes but with significant localized variations in layer height major disruptions of stratigraphy such as angular unconformities do not appear within the correlated layer sequences on local and broad scales each layer sequence exhibits a different relative accumulation rate pattern indicating that this rate has not remained constant through time and has been affected by localized processes the overall pattern of the lower layer sequence is similar to that of a classic terrestrial ice sheet with a decreasing relative accumulation rate away from the center of the polar layered deposits southward the upper layer sequence exhibits no obvious overall trends we also compare our correlation results to predictions of the effects of simple ice flow on layer structure finding that mass balance patterns have overprinted any effects of large scale ice flow flow has not been significant compared to mass balance in forming the overall structure of the correlated layers

use of mean residence time of water flowrate and equilibrium temperature indicated by water geothermometers to rank geothermal resources application to the thermal water circuits of northern calabria abstract a new hydro geochemical survey was carried out on the thermal sites of northern calabria by use of new and historical data it was possible to improve the knowledge on the deep systems of interest first thermal waters were characterized by means of a classical approach including water classifications use of the triangular diagram of cl li b and geothermometry through suitably selected functions then the tritium based mean residence time and flowrate of the thermal waters of northern calabria were used to evaluate the volume of the geothermal reservoir and its component terms based on these results the heat stored in the geothermal reservoir was computed by means of the volume method their natural heat discharge was also calculated these parameters as well as the reservoir temperature indicated by water geothermometers were used to rank the geothermal resources of northern calabria sambiase resulted to be the thermal circuit of highest geothermal potential

chemical and isotopic characteristics of the warm and cold waters of the luigiane spa near guardia piemontese calabria italy in a complex faulted geological framework abstract waters discharging at the luigiane spa come from two different hydrogeological circuits which are chiefly hosted in the carbonate rocks and upper triassic evaporites of two distinct geological units known as verbicaro unit and cetraro unit the first unit contains a cold and relatively shallow aquifer behaving as a sort of piston flow circuit with high flow rate whereas the second unit encloses a warm and comparatively deep aquifer acting as a sort of well mixed reservoir where the circulation is slower and the rate is lower meteoric waters infiltrating along the coastal chain at similar elevations 615 670 m asl on average in spite of considerable uncertainties recharge both aquifers and in the first case acquire heat from rocks through conductive transfer as a consequence of deepening along a fault system and or crossing between different systems as suggested by local structural geology in particular the warm deeper reservoir has a temperature of 60 c as indicated by the chalcedony solubility and the ca mg and so4 f geothermometers which were specifically calibrated for the peculiar water rock interaction wri processes originating the na cl so4 high salinity warm waters that discharge at the luigiane spa the warm deeper reservoir is probably located at depths close to 1 4 km assuming a geothermal gradient of 33 c km 1 the water leaving the deep reservoir discharges at the surface at 40 9 3 3 c after a relatively fast upflow and limited cooling the upward part of both hydrogeological circuits is controlled by local low and high angle fault systems as well as by the tectonic window of guardia piemontese where the verbicaro unit crops out and the cetraro unit approaches the surface the reconstruction of this conceptual model has been made possible thanks to the adoption of a local approach integrating previously existing and new geological hydrogeological and geochemical data and including the use of sulfur isotope data this last technique has proven most important as it enabled us to recognize the upper triassic fingerprint of dissolved sulfate once the effects of bacterial sulfate reduction had been properly taken into account

geomorphology and natural hazards abstract natural hazards research was initiated in the 1960 s by gilbert white and his students who promulgated a research paradigm that involved assessing risk from a natural event identifying adjustments to cope with the hazard determining people s perception of the event defining the process by which people choose adjustments and estimating the effects of public policy on the choice process studies of the physical system played an important role in early research but criticismsof the paradigm resulted in a shift to a prominence of social science geomorphologists are working to fill gaps in knowledge of the physical aspects of individual hazards but use of the information by social scientists will only occur if information is presented in a format that is useful to them one format involves identifying the hazard according to seven physical parameters established by white and his colleagues magnitude frequency duration areal extent speed of onset spatial dispersion and temporal spacing geomorphic hazards are regarded as related to landscape changes that affect human systems the processes that produce the changes are rarely geomorphic in nature but are better regarded as atmospheric or hydrologic an examination of geomorphic hazards in four fields soil erosion mass movement coastal erosion and fluvial erosion demonstrates that advances in those fields may be evaluated in terms of the seven parameters geomorphologists have contributed to hazard research by focusing on the dynamics of the landforms the prediction of occurence the determination of spatial and temporal characteristics the impact of physical characteristics on people s perception and the impact of physical characteristics on adjustment formulation opportunities for geomorphologists to improve our understanding of geomorphic hazards include research into the characteristics of the events particularly with respect to predicting the occurence and increased evaluation of the impact of human activities on natural systems

the spiral troughs of mars as cyclic steps we combine observations of stratigraphy morphology and atmospheric processes to relate the spiral troughs on mars polar layered deposits to a class of features known as cyclic steps cyclic steps are quasi stable repeating and upstream migrating bed forms that have been studied in terrestrial and submarine environments the repeating pattern is bounded by hydraulic jumps which act to stabilize the form we use radar stratigraphy from the shallow radar instrument on mars reconnaissance orbiter to examine trough evolution and constrain lateral transport we examine visible images from the thermal emission imaging system and observe low altitude clouds that we interpret to be the result of katabatic jumps i e the aeolian counterpart of hydraulic jumps in open channel flow we then devise a theoretical framework for understanding the origin of the spiral troughs that agree with 10 criteria that should be explained for any scenario to satisfactorily model the spiral troughs finally we use froude and geometrical analysis to estimate the rate of upstream migration caused by katabatic winds for the spiral troughs

the origin of conical mounds at the mouth of chasma boreale 1 one hundred and six isolated conical mound landforms were identified proximal to the north polar cap of mars at the mouth of chasma boreale five unique morphologies were identified including moderately sloped 4 6 cratered mound forms including two mounds of abalos colles flat topped moderately sloped 4 6 polygonal mound forms steeper 6 13 conical mound forms subdued mound forms with low angle slopes 0 5 3 and small 2 km diameter clustered conical forms with low to moderate angle 1 5 flank slopes from first order relationships between flank slope and the volcano productivity index volume diameter ratio 16 mounds were found to be morphologically similar to terrestrial low angle basaltic shield volcanoes thirteen mounds exhibit summit craters that range in depth d to diameter d ratio from 1 9 to 1 320 the circularity and d d ratios of mound summit craters are consistent with highly modified northern plains impact craters image analysis of shield like mounds reveals morphologic characteristics inconsistent with pristine volcanic landforms for most features horizontal flank layering 10 100 m thick polygonal map view morphology topographic relationships and spatial association with retreating polar scarps suggest that mound forms at the mouth of chasma boreale represent remnants of a once thicker more continuous sequence of near polar layered material evidence for northward scarp retreat is visible along rupes tenuis a sinuous scarp located west of chasma boreale along this scarp a single 100 m thick resistant cap unit part of the early amazonian age rupes tenuis unit is being undermined by aeolian erosion solar ablation and mass wasting remnants of the cap unit rest along the scarp margin and in places form small conical mound clusters at the base of the scarp fracture controlled retreat of the scarp is visible along the eastern portion of rupes tenuis and along the escorial crater remnant mesa where small tongue like promontories have been sculpted into the cap unit isolation of these irregularities by scarp retreat has formed several volcanic like scarp and mesa proximal mounds mound forms located closest to the retreating rupes tenuis scarp above 78 n were found to be the steepest and tallest mound landforms in the region mounds located distal to rupes tenuis were found to be broad and subdued this observation is consistent with long term retreat of a once more extensive rupes tenuis scarp and long term modification of isolated conical remnants

periodic climate change on mars review of evidence and effects on distribution of volatiles abstract the polar regions of mars preserve in both their layering and their topography a record of recent climate changes because of the coincidence of the growth of the northern seasonal cap with global dust storms dust may be currently accumulating on the northern cap but conditions at the poles will alternate with the precessional cycle deposition is also modulated by changes in eccentricity and obliquity which interact complexly affecting initiation of global dust storms the stability of volatiles at the surface and global wind regimes formation of spiral valleys and low undulations on the surface of the layered deposits may result from prefential sublimation of volatiles on sunward facing slopes and condensation on the adjacent flats with the rates also modulated by astronomically caused insolation variations lack of impact craters on the surface and lack of interruption of the layers by impact scars suggest that the polar deposits are no more than a few million years old older deposits may have been periodically removed as indicated by etch pitted terrain at the south pole and by superposition relations around the periphery of the present layered deposits evidence of ancient periodic climate changes that occurred before formation of the present layered terrain is fragmentary but includes pedestal craters parallel moraine like ridges and etched ground at high latitudes perturbation of the orbital motions also results in adsorption and desorption of volatiles in the regolith which leads to variations in atmospheric pressure and partial dehydration of the equatorial near surface materials

spiral trough diversity on the north pole of mars as seen by shallow radar sharad we combine observations from ground penetrating radar and optical instruments to conduct a comprehensive survey of spiral troughs on the north polar layered deposits of mars our survey reveals that all north polar troughs have common characteristics but there is strong regional diversity we divide the north polar layered deposits npld into eight regions based on observations of morphology and stratigraphy in order to classify the spiral troughs morphologic features that separate the regions include central promontories topographic undulations bedrock floors and trough asymmetry among others we demonstrate here that the troughs formed during two periods the first generation of troughs formed on the main lobe and in part of gemina lingula during accumulation of 600 m of ice and dust the second generation of troughs formed stratigraphically higher and immediately after large scale erosion in gemini scopuli which we conclude created the slopes necessary for troughs to form we test scenarios of trough evolution and find that only three concurrent processes are required for their formation wind transport insolation induced sublimation and atmospheric deposition our observations are inconsistent with other hypothesized processes to produce spiral troughs including incision after the formation of the npld fracturing due to flowing ice and sublimation driven patterns from insolation

groundwater pumping and land subsidence in the emilia romagna coastland italy modeling the past occurrence and the future trend 1 the emilia romagna coastland south of the po river delta italy has experienced a dramatic land settlement mainly due to the large groundwater withdrawal related to the local economic and tourist development started in the early 1950s although the use of surface water has reduced the settlement rate over the last three decades anthropogenic land subsidence still continues in a few kilometer wide coastal strip at a rate larger than the natural one the occurrence is reconstructed since 1946 with the aid of advanced finite element flow and poromechanical models implemented with a realistically detailed geology of the regional shallow multiaquifer system the models have been calibrated against the piezometric leveling and extensometer records observed over the last 50 years and a land subsidence prediction in 2016 is performed the results show that the extensive groundwater pumping that occurred in the past is most likely the main cause of the recent land settlement as well because of the delayed compaction of the clay aquitards comprised between the depleted aquifers however the available pumping data do not allow for a thorough understanding of the current local settlement process along the coastline which is the most vulnerable area of the emilia romagna region from an environmental viewpoint if the planned scenario of groundwater resource management will be implemented anthropogenic land subsidence is bound to become a marginal problem for the central and northern portion of the emilia romagna coastland

initiation of ice ages by creep instability and surging of the east antarctic ice sheet creep or shear heating instability is shown to be a plausible means of initiating a surge of the east antarctic ice sheet and plunging the earth into an ice age the occurrence of this instability requires only that the ice thickness exceed a critical value which may not be much larger than the present ice dome thickness creep instability can occur on the fast time scale of 100 1 000 yr required by inferences of past rapid cooling events and sudden rises of sea level before the onset of northern hemisphere glaciations

north polar region craterforms on mars geometric characteristics from the mars orbiter laser altimeter abstract this study focuses on topographic characterization of ice associated north polar region impact craters and several enigmatic polar craterforms using new information from the mars orbiter laser altimeter mola an instrument aboard the mars global surveyor mgs orbiter we find that for ice associated craters the topography reveals several surprising results not previously apparent from orbital images alone first geometric properties for several impact craters associated with ice and frost deposits suggest that cavity infill is as high as 80 of reconstructed preerosion levels second craters associated with ice also demonstrate unique cavity geometries relative to their nonpolar counterparts finally in some cases ice associated impact features are anomalously deep on the basis of depths modeled from the best available scaling laws we suggest that burial of these impact features by either episodic advance of the polar cap margin or by continuous deposition at the highest rates previously estimated for the north polar region of mars has occurred subsequent stripping has exhumed the features leaving behind cavity infill deposits and a few of these display topographic levels above the surrounding preimpact surface in at least one case cavity interior deposits show layering with a typical thickness of 10 m suggesting episodic deposition and ablation of materials as in the polar layered terrain in addition to ice associated craters we investigated the topography of several enigmatic polar craterforms in particular a few craterforms within 150 km of the permanent north polar cap appear to resemble simple effusive lava shield volcanoes found on earth their geometric properties cannot be reconciled with previous suggestions that they were manifestations of martian hydromagmatic processes i e maar volcanism mola s initial measurements of impact craters and other craterforms in the north polar latitudes of mars support the concept of a geologically recent surface with evidence of effusive volcanism and enhanced sedimentation in addition the measured impact crater depths for ice associated craters suggest at least a few cases of enhanced excavation and thus a possibly weaker target relative to the typical northern hemisphere plains

photoclinometric determination of the topography of the martian north polar cap abstract photoclinometry is useful for the determination of topography for areas which have a uniform albedo the technique is applied to early spring viking images of the martian north polar cap taken when the surface was covered by a nearly uniform frost cover unlike earlier approaches the topographic profiling can be used for surfaces with any photometric function but the strike of the planetary surface relative to the illumination angle must be specified along the profile the resultant profiles are relatively insensitive to misestimation of the photometric functin and slope orientation but are quite sensitive to the assumed values of the reflectance of an equivalent level surface and the atmospheric opacity if it is large

geologic history of the polar regions of mars based on mars global surveyor data ii amazonian period based on mars orbiter laser altimeter mola and mars orbiter camera moc observations of amazonian polar layered deposits pld morphology composition and thickness we conclude that the plds are composed of porous unconsolidated layers that have not experienced significant basal melting or other glacial type processes morphologic features and associations within the pld chasmata including preserved craters and sinuous ridges indicate that the dominant process of chasmata formation is wind scouring our detailed analysis of south polar spiral trough topography in conjunction with the identification of similar layered stratigraphy within north polar spiral troughs suggests that trough migration due to preferential ablation of sun facing slopes cannot be demonstrated within the layered sequences we have not identified widespread unconformities discontinuities or pinch outs that would indicate an accublation origin of the plds we therefore postulate that the well defined plds at both poles eventually reached and maintained their present form following deposition without extensive deformation or redeposition large cuspate ridges in the ultimi lobe of planum australe appear to be layered and may be unusual erosional remnants of a once thicker pld in this area beneath the north polar layered deposits in planum boreum we have identified a platform of older highly degraded polar deposits as much as a kilometer thick that may have once covered an area larger than planum boreum

new insights into the late amazonian zonal shrinkage of the martian south polar plateau the martian south polar plateau planum australe comprises the largest known water ice surface deposit on the planet here we present evidence for an episode of extensive polar plateau retreat during the late amazonian which affected regions flanking circum polar terrains located between cavi angusti and sisyphi montes

topography and stratigraphy of martian polar layered deposits abstract topography and stratigraphy of young sediments in the martian north polar region are being studied from high resolution viking orbiter images to test and constrain theories of terrain evolution driven by cyclical climate change several steepened slopes upon which layers are exposed in section were found to have local relief of 200 to 800 m and slopes ranging from 1 to 8 first attempts to calculate average layer thicknesses from portions of sections yielded results ranging from 14 to 46 m linearly correlated with slope in some cases under the assumption of short range lateral continuity a greater number of layers was inferred to be present than was actually resolved on a particular section when apparent layer thickness are revised accordingly the correlation with slope is destroyed we conclude that images of the shallowest sloping sections of layered deposits should yield the most stratigraphic information and layers thinner than 14 m may occur indeed they may even be common or typical because of the sensitivity of summer frost distribution to local slope and other properties of exposed strata interseasonal comparisons of images promise to enhance the capability to detect layers and differentiate them by material properties

hydrogeochemical study of an ophiolitic aquifer a case study of lago southern italy calabria a hydrogeochemical survey was carried out in the area of lago calabria region southern italy and outcropping geological units were classified from the hydrogeological point of view to explain the evolution of local groundwaters in addition reaction path modeling was performed to simulate the evolution of groundwaters upon interaction with local metabasalts phyllites and serpentinites by means of the eq3 6 software package version 8 0 simulations were carried at constant temperature of 14 1 c which reproduces the average temperature of local groundwaters three different simulations have been performed for the average metabasalt fixing the fugacity of co2 at either 10 2 4 bar mean value 10 2 0 bar mean value 1 or 10 2 9 bar mean value 1 the simulation for the average serpentinite and phyllite was carried out at the mean value of the fugacity of co2 10 2 4 bar all evidences acquired in this study namely the hydrogeological framework the chemical analysis of local groundwaters and the results of reaction path modeling consistently point out that groundwater circulation under ordinary hydraulic gradient primarily occurs in the ophiolitic sub complex and that dissolution of metabasalts and serpentinites controls the chemical characteristics of the groundwaters from the study area

the role of eolian processes in forming surface features of the martian polar layered deposits abstract the major topographic features of the martian polar layered deposits include the conspicuous spiral troughs subtle undulations broad reentrants chasma steep arcuate scarps and dune fields a prominent role for eolian processes in the formation of all of these features is proposed strong katabatic winds occur on the north polar cap producing widespread frost streaks these cold drainage winds are analogous to those on the terrestrial antarctic cap in the chasmae convergent katabatic winds create yardangs and erode arcuate scarps in the layered deposits that are also the source for local dune fields migrating outward from the polar cap the chasmae are postulated to originate by long term erosion by katabatic wind wind plays a role in formation of the troughs and scarps primarily through removal of dust freed from exposed layered deposits by ablation of ice on defrosted equator facing slopes the undulations are created by interaction between surface erosion or deposition of perennial ice and standing waves in the shallow katabatic windflow the south polar layered deposits exhibit topographic features similar to those at the north polar cap but erosion and depositional processes creating these features may be inactive during the current epoch because of the lack of an extensive perennial ice cover and associated katabatic wind

recent formation and evolution of northern martian polar layered deposits as inferred from a global climate model 1 we present a time marching model which simulates the exchange of water ice between the martian northern cap the tropics and a high latitude surface reservoir net annual exchange rates of water and their sensitivity to variations in orbital rotational parameters are examined using the martian water cycle modeled by the lmd three dimensional global climate model these rates are propagated over the last 10 myr to follow the thickness of the reservoirs the effect of a sublimation dust lag is taken account to test simple models of layer formation periods of high mean polar summer insolation 5 10 ma ago lead to a rapid exhaustion of a northern polar cap and a prolonged formation of tropical glaciers the formation of a northern cap and of a high latitude icy mantle may have started 4 ma ago with the average decrease of polar insolation tropical ice may have disappeared around 2 7 ma ago but small glaciers could have formed during the last peaks of polar summer insolation over the last 4 myr most of the present cap may have formed at the expense of tropical and high latitude reservoirs forming distinct layers at almost each 51 kyr 120 kyr insolation cycle layers thickness ranges from 10 to 80 m variations being produced by the modulation of the obliquity with 2 4 and 1 3 myr periods because only 30 insolation cycles have occurred since 4 ma ago we found an inconsistency between the recent astronomical forcing the observed number of layers and simple astronomically based scenarios of layers formation

identification of soil erosion and fluvial sediment problems a computer model has been used to estimate soil loss and sediment yield from irregular field size units of small watersheds input to the model includes spring data i e relating to february through may for the independent variables of the universal soil loss equation and for factors such as surface roughness an index of overland runoff and proximity to the stream output from the model includes maps of seasonal estimates of potential soil losses field sediment delivery ratios and expected sediment yields on the basis of selected erosion and sediment yield tolerances the output information has been analysed to identify watershed areas which 1 exhibit both erosion and sediment yield problems 2 exhibit only erosion problems 3 exhibit only sediment yield problems and 4 exhibit neither erosion nor sediment yield problems the percentage of the watershed area in each category and the percentage of the watershed soil loss and sediment loads contributed by each category are also identified application of the procedure for planning remedial control programs for five watersheds is discussed

a subsurface depocenter in the south polar layered deposits of mars the south polar layered deposits spld are one of the largest water ice reservoirs on mars and their accumulation is driven by variations in the climate primarily controlled by orbital forcings patterns of subsurface layering in the spld provide important information about past atmospheric dust content periods of substantial erosion and variations in local or regional deposition here we analyze the spld using shallow radar sharad sounder data to gain a unique perspective on the interior structure of the deposits and to determine what subsurface layers indicate about the preserved climate history sharad data reveal a major deviation from the gently domical layering typical of the spld a subsurface elongate dome the dome most likely formed due to variations in the accumulation of ice and snow across the cap with a higher rate occurring in this region over a prolonged period this spld depositional center provides an important marker of south polar climate patterns

isotopic composition of precipitation in italy a first overall map abstract composite monthly samples of atmospheric precipitation were collected over different periods of time ranging from one to seven years at 77 different locations throughout italy these samples were measured for their oxygen and hydrogen isotopic composition to obtain basic information for hydrological and meteorological studies in this area on the basis of the results obtained a first map of the isotopic composition of precipitations in italy has been drawn up the main features of this map are the following 1 no isotopic latitudinal gradient has been found along the tyrrhenian coast from sicily to the italian french border despite the considerable range of latitude 2 a minor latitudinal gradient is found in the southeasternmost section of the country apulia partially favored by the local morphology 3 a marked shadow effect of the apennines is apparent along the southern section of the po valley and along the central section of the adriatic coast 4 the contribution of water vapor from the northernmost section of the adriatic sea affects the eastern and central sections of the po plain 5 the shadow effect of the alps is considerably smaller than expected 6 the isotopic vertical gradients calculated in nine different areas and based on groups of two to five different stations vary but are essentially close to about 0 2 100 m 7 when mean monthly temperature values were available their relationship with the isotopic composition of precipitation was found to be on average very poor 8 the relationship between mean 18o and mean d calculated for the collection locations shows shifts of both the slope and the deuterium excess when compared to the global meteoric water line these shifts are different for northern central and southern italy 9 in a few cases anomalously low monthly values suggest the existence of pronounced amount effects

the oxygen and carbon isotope distribution in the mediterranean water masses abstract the oxygen and carbon stable isotope compositions of the present day mediterranean waters have been measured in order to evaluate their variability which is related to the specific climatic and hydrological conditions within the basin the experimental equation between the 18 o value and the salinity of water based on 300 measurements on surface intermediate and deep waters sampled during the vicomed 2 and 3 cruises in the western central and eastern mediterranean has a slope of 0 27 a value which is significantly lower than the slope of 0 45 as defined in the northeast atlantic ocean this difference in the 18 o salinity relationship which occurs immediately in the alboran basin is basically a characteristic of the climatic regime of the mediterranean i e of an excess evaporation over fresh water input the largest variations of these two parameters 18 o of water and 13 c of co 2 are observed in the surface waters mostly in the western mediterranean this evolution mirrors the progressive eastward restriction which separates the less evaporated and more productive western basins from the more evaporated and less productive eastern basins the intermediate waters constitute a homogeneous layer however their 18 o values decrease eastward by 0 35 at maximum due to progressive dilution by mixing with overlying and underlying water masses their 13 c values decrease also eastward by 0 35 at maximum due to an increasing input of nutrients issued from the regeneration of sinking organic particles the deep waters have similar 18 o values but slightly higher 13 c values often by less than 0 1 than the overlying intermediate waters indicating generally well ventilated conditions due to active winter convection

global patterns in cloud forms on mars abstract mariner 9 images and all viking orbiter images through july 1979 were searched for cloud forms a computer accessible catalog was assembled consisting of a classification of cloud type lee wav wave for example and properties directionality wavelength for example lee wave directionality shows a pattern and seasonal variation at high latitudes which is consistent with predictions of theoretical modeling fog and haze occurrence shows no obvious correlation with water abundance or any other simple causal factor lee waves are rare at equatorial latitudes plumes probably dust occur preferentially at locations where strong boundary layer convection is expected