scaling and parametrization of clear sky solar radiation over complex topography 1 solar radiation at the land surface is influenced by slope aspect shadows and obstruction of the sky all of which vary over a wide range of length scales in regions of complex topography with important consequences for the surface energy balance atmospheric models however generally assume the surface to be flat on subgrid scales for four areas in north america ranging in latitude from 39 n to 69 n and in topography from rolling to mountainous we simulate spatial patterns of clear sky incoming solar radiation it is found that distributions of slope components and variations in shaded area with solar elevation can be approximated by simple functions that scale to each of the areas studied from these results parametrizations are developed for averages standard deviations and distributions of direct beam and diffuse solar radiation results from these parametrizations and from a modified form of a simpler parametrization presented previously compare well with statistics from the spatial simulations the only topographic input required by the parametrizations is the standard deviation of slope components this parameter is again found to have simple scaling relationships with the resolution and extent of the underlying elevation grid and with the standard deviation of elevation

plant fossil distributions in some australian permian non marine sediments abstract plant remains occur in all post devonian lowland terrestrial depositional systems with distinctive assemblages characterizing discrete environments glossopterid gymnosperms dominate most australian permian coal bearing sediments herbaceous pteridophytes sphenophytes and lycophytes are best represented in lower deltaic lacustrine and paludal deposits non glossopterid gymnosperms mostly colonized drier floodplain and upland environments and are poorly represented in australian permian sequences fresh and brackish water algae are abundantly preserved in paludal and lacustrine facies in both alluvial and delta plain environments seasonal productivity and taphonomic factors undoubtedly influenced the composition of interseam compression impression floras but integration of information from these assemblages with that from permineralized peats in situ coalified plants and coal maceral and palynological analyses can assist in the interpretation of australian permian coal forming environments and the structure of plant communities

the influence of the layered character of snow cover on the triggering of slab avalanches one of the principal aims of avalanche warning is to prevent slab avalanches triggered by skiers other than explosives the best practical tool for stability evaluation is the rutschblock test whether the slab may be triggered by a skier depends on various slab characteristics important factors seem to be depth of the weak layer slab hardness and sublayering of the slab the stress distribution induced by a skier is calculated by the finite element method for typical snow cover configurations the additional shear stress is of the same order of magnitude as the shear strength of weak layers besides the critical weak layer prerequisite for a slab avalanche hard layers seem to be important the analysis suggests that a shear failure is most probable at the transition from a hard to a soft layer this corresponds well to observations of slab avalanche profiles the results may help to improve and quantify the analysis of snow profiles

study of the snow melt freeze cycle using multi sensor data and snow modelling the melt cycle of snow is investigated by combining ground based microwave radiometric measurements with conventional and meteorological data and by using a hydrological snow model measurements at 2000 m a s l in the basin of the cor devole river in the eastern italian alps confirm the high sensitivity of microwave emission at 19 and 37 ghz to the snow melt freeze cycle while the brightness at 6 8 ghz is mostly related to underlying soil simulations of snowpack changes performed by means of hydrological and electromagnetic models driven with meteorological and snow data provide additional insight into these processes and contribute to the interpretation of the experimental data

the rise and demise of podozamites in east asia an extinct conifer life style abstract in the late triassic early jurassic forests dominated by podozamites an apparently deciduous shoot dropping conifer with broad multi veined leaves were extensive in what were the mid latitudes of eastern asia podozamites was the only conifer in many forests of this region and at times appeared to have formed an almost mono specific vegetation podozamites appears to have been little effected through the triassic jurassic transition but responded to climate changes later in the jurassic the chinese region progressively dried through the middle jurassic and aridity had developed in some areas by the late jurassic early cretaceous the centre of distribution of podozamites shifted north to the siberian region where conditions remained wet there it typically coexisted with conifers having a diverse range of smaller leaf morphologies by the late albian angiosperms had arrived in the siberian area and risen to dominance some time after this event podozamites became extinct this is significant as it represents the permanent extinction of a unique lifestyle a deciduous broad leaved and multi veined conifer the broad history of podozamites raises some interesting issues 1 the existence of a large dominantly deciduous vegetation at mid latitudes in the late triassic early jurassic is little discussed 2 it is unexpected that as broad leaved angiosperms took over amongst the conifers it was the broad leaved multi veined podozamites that became extinct this is the morphology that might have been expected to compete with the apparently more shade forming angiosperms instead it was the smaller leaved and single veined conifers that remained to coexist with the angiosperms

observations on the nature and origin of fusain abstract evidence for a wildfire origin of fusain is examined charcoal produced by natural fires and artificial charring resembles fossil fusain both in physical size and shape and in optical reflectance artificially charred leaves and naturally burnt wood are illustrated using the sem reflectance studies on modern charcoals suggest that much semifusinite may be produced by pyrolysis the ecological implications of a wildfire origin of fusain are discussed and it is concluded that fires have been a feature of terrestrial ecosystems from at least the late devonian

impact of a climate change on avalanche hazard the safran crocus mepra software is used to assess the climatology of the avalanche hazard and its sensitivity to climate change a natural avalanche hazard index based on mepra analysis is defined and validated against natural avalanche observations triggered avalanches are not taken into account a 15 year climatology then allows a comparison of avalanche hazard in the different french massifs finally a simple climate scenario with a general increase of precipitation and temperature shows that avalanche hazard may decrease slightly in winter mainly february and more significantly in may june the relative proportion of wet snow avalanches increases

dense avalanche friction coefficients influence of physical properties of snow the values of the voellmy friction parameters of 735 historical avalanches that have occurred along 26 paths in the chamonix valley france since 1958 are back analyzed with a depth averaged hydraulic model including sub models for erosion entrainment and deposition for each path the longitudinal and crosswise topographic profiles were derived from a high resolution digital elevation model acquired by laser scanning the initial snow depth and snow cohesion as well as various physical properties of snow were computed from numerical simulations of the detailed snowpack model crocus fed by the safran meteorological analysis for each event the full ranges of the two friction parameters were scanned and the pairs of friction parameters for which the run out altitude is found close enough to the observed one with an uncertainty of 5 m were retained statistical class analysis was used to investigate the correlation between the obtained friction coefficients and the snow physical properties no evident trend with the snow parameters was found for the inertial friction coefficient for the static friction coefficient an increasing trend with temperature and density was observed as well as a decreasing trend with liquid water content and initial snow depth although modeling assumptions and limitations regarding data and the calibration procedure should be kept in mind these trends are worth noting allowing avalanche simulations to be refined to take into account prevailing weather and snow conditions

discussion on the concepts in paleoenvironmental reconstruction from coal macerals and petrographic indices abstract organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions this allows the relation of coal composition to mire ecosystems or environments coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments many authors proposed relations between specific maceral assemblages and or micro lithotypes and peat forming environments the key controlling factors which affect peat environment include hydrogeology redox ph vegetation type clastic influx sedimentation and peat accumulation rate etc recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models the main reasons for the failure of the petrographic models are oversimplification of the effects of humification on tissue preservation vs destruction the use of post diagenetic processes e g geochemical gelification in determining depositional environments changes in petrographic composition related to floral evolution geological age rank increase and compaction lack of distinction between different inertinite maceral in some models here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo environmental reconstruction are discussed a multi disciplinary approach including petrography palynology chemistry etc has been recommended which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation

spatial patterns of snow stability throughout a small mountain range this research investigates snow stability on the eastern side of a small mountain range in southwest montana u s a on one mid season day and one late season day during the 1996 97 winter although previous research has addressed snow stability at smaller spatial scales this is the first field based study to investigate snow stability as measured by stability tests over a mountain range in order to better understand its spatial distribution and the implications for predicting dry slab avalanches using helicopter access six two person sampling teams collected data from over 70 sites on each of the two sampling days variables for terrain snowpack snow strength and snow stability were generated from the field data and analyzed using descriptive statistics correlation analysis and multiple regression results from the first sampling day show stability is only weakly linked to terrain snowpack and snow strength variables due to consistently stormy weather conditions leading up to that day the second field day s results demonstrate a stronger relationship between stability and the other variables due to more variable weather conditions that ranged from periods of sunshine to storms on both days stability decreased on high elevation northerly facing slopes the data structure complexity provides insights into the difficulties faced by both scientists and conventional avalanche forecasters in predicting snow avalanches

early to middle jurassic vegetation and climatic events in the qaidam basin northwest china abstract jurassic deposits are well exposed in the qaidam basin qinghai province northwest china and are regarded as one of the most completely developed early middle jurassic plant bearing sequences in northern china the early to middle jurassic palynoflora in this basin shows a high diversity of spores and pollen grains which are characterized by four palynological assemblage zones corresponding to the pliensbachian toarcian aalenian bajocian and bathonian in age vegetation reconstruction demonstrates four vegetation types upland coniferous forest in the pliensbachian coastal cheirolepidiacean forest in the toarcian lowland fern forest in the aalenian bajocian and a mixed forest in the bathonian nearest living relative analysis of the major plant groups shows that the early to middle jurassic vegetation in the qaidam basin not only consists of plants with tropical subtropical climate requirements but also those indicating temperate climatic conditions in addition bryophytes and fungi as well as cheirolepidiaceae which are generally considered to indicate warmer and or drier conditions are also documented in the palynofloras it is suggested that a temperate to subtropical climate generally prevailed during the early to middle jurassic in this basin however the vegetation features and the sedimentary data signify that an overall humid to semi humid phase was punctuated by warmer and locally dry and or arid episodes the two higher temperature and aridity events occurred in the toarcian and bathonian callovian periods in the qaidam basin these climatic events can be inferred by increase of relative abundance of classopollis pollen some tropical subtropical fern spores and the occurrences of variegated red beds and evaporite rocks these events may either be associated in some way with a transient global warming phenomenon due to an enhanced greenhouse effect or be linked with intensification of a potential monsoonal circulation such events finally caused a weakening and even arrested coal accumulation in the qaidam basin during the toarcian and the bathonian callovian intervals

characterization and quantification of inorganic constituents of tropical peats and organic rich deposits from tasek bera peninsular malaysia implications for coals abstract since the carboniferous tropical latitudes have been the site of formation of many economic coal deposits most of which have a restricted range of mineralogical composition as a result of their depositional environment climatic conditions and diagenesis mineralogical and microscopic investigations of tropical peats from tasek bera peninsular malaysia were performed in order to better understand some of these factors controlling the nature distribution and association of inorganic matter in peat forming environments distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system because the inorganic composition of peat deposits is determined by plant communities height of water table and climate the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions tasek bera is a peat accumulating basin in humid tropical malaysia with organic deposits of low to high ash yield and thus representative of many ancient peat forming environments clay minerals dominate the mineralogical composition of the peat and organic rich sediments while quartz and clays dominate the underlying siliciclastic deposits kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite particle size analyses indicate that 50 of the inorganic detrital fraction is 75 of the ash constituents as a consequence the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals the ash content of the often inundated peat consists on average of 10 opaline silica from diatoms and sponge spicules while the ash of the top deposits may have up to 50 biogenic silica hence al and si hydroxides and the opaline silica from diatoms and sponges represent a large repository of al and si which may form the basis of mineral transformation neoformation and alteration processes during coalification of the peat deposits as a result most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays such as kaolinite detrital kaolinite resilisified kaolinite or desilisified gibbsite or illite and various amounts of detrital and authigenetic quartz

late pleistocene catchment wide denudation patterns across the european alps abstract we compile detrital 10be concentrations of alpine rivers representing the denudation rates pattern for 375 catchments across the entire european alps using a homogeneized framework we employ state of the art techniques for inverting in situ 10be concentrations into denudation rates from our compilation we find that i while lithologic properties and precipitation runoff do influence erosion mechanisms and rates at the scale of individual catchments and in some specific alpine regions such controls do not directly stand for the entire alps ii as also previously suggested catchment wide denudation rates across the entire european alps closely follow first order alpine topographic metrics at the scale of individual catchments or selected alpine sub regions however in addition to previous local scale studies conducted in the european alps our large scale compilation highlights a functional relationship between catchment wide denudation and mean catchment slope angle catchment wide denudation positively correlates with mean catchment slope up to a threshold angle 25 30 above this threshold any correlation between catchment wide denudation and slope as well as other catchment metrics breaks apart we can reconcile these systematic patterns by proposing a regional erosion model based on diffusive transport laws for catchments located below the slope threshold angle in oversteepened catchments situated above threshold slopes erosion is stochastic in nature as glacial carving likely caused a partial decoupling between hillslope and fluvial domains with complex topographic relationships and sediment connectivity patterns finally we identify a first order positive relationship between modern geodetic rock uplift and catchment wide denudation for the european alps the observed spatial pattern is highly variable and possibly reflects the surface response to deep geodynamic mechanisms prevailing in the different alpine regions we conclude that today s topography and geomorphic features of the entire alps are the result of a millenial scale geomorphic response to past glacial processes and active rock uplift highlighting a link between external and internal drivers for mountain erosion

a computer based system simulating snowpack structures as a tool for regional avalanche forecasting this paper describes the current state of a complete automatic system of three numerical models that simulate snow cover stratigraphy and avalanche risks for operational avalanche forecasting the first model safran estimates relevant meteorological parameters affecting snowpack evolution the second crocus is a snow numerical model which simulates the physical processes inside the snowpack and its stratigraphy the last model mepra is an expert system based on an assessment of snowpack stability it deduces natural and accidental avalanche risks to describe the great variability of the snowpack and the associated avalanche risks this automatic system simulates snow cover evolution and its stability for many typical slopes elevations and aspects representative of the different french massifs to achieve this result different kinds of validations have been carried out since winter 1981 they are mainly based on comparisons with different sets of measurements and on the opinion of users although the routinely obtained results do not yet take into account all small scale effects such as wind transport they have been considered as valuable information by avalanche forecasters since 1992 93 and used operationally since then

new record of fossil wood xenoxylon from the late triassic in the sichuan basin southern china and its paleoclimatic implications abstract fossil wood is one of the significant proxies for terrestrial paleoclimate and paleogeographical reconstruction in earth history abundant and diversified mesozoic fossil woods are well recorded in china however triassic fossil wood is very scarce here we report a new fossil wood from the late triassic xujiahe formation norian to rhaetian in guangyuan of northern sichuan basin southwestern china the fossil wood material consists of two well preserved specimens yielding secondary xylem with distinct growth rings bordered pits on the radial tracheid walls are mostly contiguous biseriate alternate locally uniseriate and strongly flattened cross fields show a large window like pore this anatomy is typical for the important fossil wood morphogenus xenoxylon gothan and based on a novel combination of radial and cross field pitting type and ray height a new species xenoxylon guangyuanense sp nov is recognized the finding of this new fossil wood taxon contributes to a better understanding of the yet poorly documented xenoxylon early radiation during the late triassic as well as of the origin of x meisteri group a peculiar endemic group which diversified in far east asia from the triassic to the early cretaceous xenoxylon is a paleobiogeographically significant genus being bound to cooler and or wetter climates of northern hemisphere throughout its late triassic late cretaceous range the occurrence of xenoxylon in the sichuan basin of southern china may indicate a short term cooling event sandwiched within a period during which warm and wet climate conditions largely prevailed over lower latitude regions of the northern hemisphere such a cooling event in the sichuan basin which was located at a low paleolatitude on the eastern rim of tethys may be in accordance in time with the temperature decline event in norian rhaetian boundary uncovered by oxygen isotope 18 o record in italy of the western rim of tethys

monitoring of snow avalanches using a seismic array location speed estimation and relationships to meteorological variables 1 monitoring snow avalanches is necessary in order to better understand their triggering mechanisms and ultimately improve forecast performance seismic monitoring has been developed by several groups over the last 20 years and holds great potential to detect locate and characterize snow avalanches during the 2009 2010 winter a seismic antenna was installed in the french alps close to the village of saint christophe en oisans 1700 m above sea level the array of seven sensors operated during 50 days in october and november 2009 under snow free conditions and during 40 days in january and february 2010 in presence of snow it recorded different types of seismic events including snow avalanches rockfalls shots and regional and local microearthquakes eighty avalanche signals were visually identified using a beam forming method we were able to locate snow avalanches on slopes of various orientations in a radius of about 3 km and track their propagation the location technique allowed for the estimation of avalanches front speed which ranged between 12 and 32 m s 1 the method can also distinguish dry and wet snow avalanches durations of avalanches can be as long as 380 s because of the length of the slopes in the area seismic monitoring provides a catalog of avalanches with precise times which can be used to analyze the impact of meteorological forcings on the avalanche triggering snowfall is found to be the dominant forcing of avalanche activity during this period as revealed by the strongest correlation for the period of study our results suggest that the impact of precipitation on the snowpack instability lasts for about 6 days

xenoxylon a boreal fossil wood in the mesozoic redbeds of southeast asia potential for the stratigraphy of the khorat group and the palinspatic reconstruction of southeast asia abstract the fossil wood genus xenoxylon is reported in situ for the first time in thailand it originates from the indosinian terrane from the mesozoic continental redbeds of the phu kradung formation khorat group palinspatic reconstruction palaeobiogeography and correlation with other occurrences of the genus in southern china as well as in vietnam suggest a middle to late jurassic age for the phu kradung formation level yielding the fossil wood the dating of this formation is still controversial and thus our data is an important step towards a better understanding of its geological history and palaeoecology as well as of the southeast asia mesozoic continental redbeds significance for the evolution of the vertebrates

petrographic facies analysis of lower and middle jurassic coal seams on the island of bornholm denmark abstract the lower middle jurassic succession on the island of bornholm denmark comprises a wide range of clastic depositional environments lacustrine fluvial coastal plain tidal flat and shallow marine the succession contains a number of coal seams and carbonaceous seams permitting 1 evaluation of the relationship between the different clastic environments and the associated environments of organic matter deposition and 2 assessment of facies changes within coal carbonaceous seams from different peat forming environments coal petrographic facies analysis was performed by maceral analysis of 61 coal samples from the lower jurassic ronne formation comprising the munkerup member sose bugt member and galgelokke member and from the upper lower middle jurassic baga formation the seams in the munkerup member and the sose bugt member are mainly allochthonous whereas those of the galgelokke member and the baga formation are mainly autochthonous the seams represent a broad spectrum of depositional environments from raised bogs to freshwater swamps and marine influenced swamps the facies are subaquatic to telmatic and terrestrial compositional differences between the seams are attributed to vegetation characteristics depositional facies and differences in the degradation of the organic matter the original peat forming vegetation was composed of cellulose rich shrub like plants tree ferns herbaceous plant communities and a varying amount of trees the peat forming environments represented by the carbonaceous seams in the munkerup and sose bugt members are compatible with the depositional environments indicated by the sediments however the coal seam in the galgelokke member represents deposition in a raised bog conflicting with sedimentary interpretation of a clastic tidal flat environment for the member the baga formation is considered to have formed under a lower upper delta plain or fluvial environment the composition of the coal seams supports the interpretation of a system of meandering streams in a upper delta plain to fluvial environment

isometamorphic variations in the reflectance and fluorescence of vitrinite a key to depositional environment abstract petrographic investigations of serial ply samples from five high to medium volatile bituminous coal seams from australia 4 and canada 1 reveal substantial in seam variations in the reflectance and monochromatic microfluorescence intensities of the maceral subgroup telovitrinite the variations consist of one case of reflectance enhancement and fluorescence suppression and four cases of reflectance suppression and fluorescence enhancement the single case of reflectance enhancement and fluorescence suppression is due to the oxidation of the vitrinite nuclei at the sequence boundary between the bayswater and upper wynn seams in new south wales the four cases of reflectance suppression and fluorescence enhancement result from the syn and epigenetic absorption by the vitrinite nuclei of hydrogen donated by presumably anaerobic bacteria generated lipids two of the coals are marine influenced the liskeard seam from the bowen basin by combined syngenetic and epigenetic effects and the greta seam from the sydney basin mainly by epigenetic contact with sea water for both coals the results are strong vitrinite reflectance suppression and fluorescence enhancement the remaining two coals the bulli seam from the sydney basin and a coal seam from the gates formation in british columbia show moderate epigenetic effects on the optical properties of telovitrinite by fresh water in the bulli seam which was studied in two adjacent localities the reflectance suppression and fluorescence enhancement of telovitrinite are stronger under sandstone roof than under shale roof in some cases the epigenetic effects are superimposed on syngenetic telovitrinite reflectance and fluorescence variations resulting from the cogeneration and mixing of different telovitrinite precursors for example autochthonous roots and hypautochthonous or allochthonous shoots a measure of the degree of dispersal and mixing is the coefficient of variation of telovitrinite reflectance and or fluorescence this coefficient correlates well with detrital minerals and dispersed macerals e g inertodetrinite and to a lesser extent sporinite some comments are made on slitted so called pseudovitrinite which is regarded as a telovitrinite that was subjected to very weak post coalification desiccation and possibly oxidation without losing much of its thermoplastic properties

two dimensional numerical modelling of surface wind velocity and associated snowdrift effects over complex mountainous topography a new experimental software for blowing snow sytron2 is pre sented it takes advantage of the previous limited realization sytron1andof the entire real time operational environment of the automatic chain safran crocus mepra scm it runs presently on a rectangular grid with a mesh size of about 45m covering an area of 3 0 3 0km 2 around the observation test site col du lac blanc french alps 2700m a s l near the alpe d huez ski resort sytron2 is initialized with a realistic snowpack representation derived fromthe scmoutputs andcoupledto awind fieldcom puted by the new samver model the final aim is to build a fully embedded tool sui table for representing snowdrift effects with a better resolution at different specific locations the different tools and operators used are described as well as the field valida tion processes which are based on remote identification of the eroded and accumulated areas using digital pictures

linking the effective thermal conductivity of snow to its shear strength and density 1 the effective thermal conductivity of snow keff is a crucial climatic and environmental variable here we test the intuition that keff is linked to microstructural and mechanical properties by attempting to relate keff to density snow and to shear strength measured with a handheld shear vane we performed 106 combined measurements of keff snow and in the alps svalbard arctic alaska and near the north pole covering essentially all snow types we find a good correlation between keff and snow which is not significantly different from that of sturm et al 1997 the correlation between keff and a combination of and snow is stronger than with density alone we propose an equation linking keff w m 1 k 1 snow kg m 3 and pa keff 7 114 10 5 snow 0 333 2 367 10 2 this equation places constraints on the calculation of keff snow and in avalanche warning models where is a key variable for our samples we calculate from measured values of keff and snow using our equation and compare the value to that predicted by the french mepra avalanche warning model which uses density and grain type as input data mepra and the prediction of based on keff and snow agree within 8 mepra agrees with observations within 11 calculating from density only yields values 55 lower than measured showing the interest of using additional data to predict

low ash peat deposits from a dendritic intermontane basin in the tropics a new model for good quality coals many good quality thick low ash carboniferous cretaceous and tertiary coal deposits have dulling upward sequences that have been interpreted to be of ombrotrophic lowland coastal origin previous studies of potential modern analogues for thick dulling upward coal sequences have focused on tropical ombrotrophic coastal peats however most modern coastal ombrotrophic deposits would yield all bright coal seams new evidence from peat deposits of the southern intermontane tasek bera basin western malaysia reveals that thick low ash low sulfur peat may originate in narrow tributary valleys with moderately steep flank gradients these deposits may be favorable precursors to dulling upward coals in that they contain high wood and low ash content at depth and medium wood and slightly increasing ash content in the upper parts peat accumulation in the tasek bera basin began in mid holocene time during the past 4500 years 500 cm of low ash 40 cm white fluvial silty clay with wood fragments was deposited the clay rich sediments are overlain by limnic black mud sandy clay and dark brown mud rich peat up to 70 cm thick the ash content of the mud rich peat is as high as 31 wt the high ash peat is overlain by low ash sapric to hemic peat up to 5 m thick the basal 3 m of the peat deposits contain abundant logs and large woody fragments whereas the top 2 m have less hard wood but more arborescent fragments of palmae such as roots from pandanus atrocarpus the acrotelm top 50 cm has a low to medium ash content 10 wt with burial the deposits of southern tasek bera basin would yield a dendritic sediment pattern of sandstone shale carbonaceous shale and a dulling upward vitrain rich coal overlain by carbonaceous shale because of the dendritic nature of the tasek bera basin coal seams would most likely have a similar pattern as the carboniferous humic coal deposits of the black warrior basin in alabama usa however the good quality coals with dulling upward characteristics would be concentrated in the southern tributaries of the basin

delineation of the distinctive nature of tertiary coal beds abstract floral character in mires has changed progressively through time in the carboniferous pteridophytes sphenophytes and lycophytes were dominant but by the permian gymnosperms were an important component of mire flora during the early mesozoic gymnosperms remained the characteristic mire vegetation together with pteridophytes and conifers became dominant during the jurassic cretaceous and paleocene vegetation are similar with taxodiaceous flora being important in mire vegetation from the eocene onwards however angiosperms were increasingly dominant in mire communities and in the miocene herbaceous vegetation began to play a significant role together with these changes in floral character at least three aspects of coal character also appear to vary sequentially with time and are distinctive in the tertiary 1 proportions and thickness of vitrain banding 2 coal bed thickness and 3 proportions of carbonised material a compilation has been made of data from the coal literature comparing older coals with those of the tertiary in order to give a perspective in which to examine tertiary coals it was found that only tertiary coals contain significant proportions of coal devoid of vitrain bands in addition tertiary coals are the thickest recorded coal beds and generally contain low percentages of carbonised material many less than 5 as compared to older coals it is interesting to note that paleocene coal beds are similar to cretaceous coals in that they tend to be thinner and contain higher proportions of carbonised material than do younger tertiary coals the absence of vitrain bands in some tertiary coal beds is thought to result from the floras dominated by angiosperms which are relatively easily degraded as compared to gymnosperms the thickness of tertiary coals may be related to an increase in biomass production from the carboniferous through to the tertiary as plants made less investment in producing lignin an energy intensive process in addition with less lignin in plants easier degradation of biomass may have facilitated nutrient recycling which in turn led to greater biomass production increased biomass production may have also diluted the carbonised material present in some tertiary peats leading to lower proportions in the coal another possible cause of decreased carbonised components in tertiary coal is that decreasing lignin content resulted in decreased charring during fires as lignin is particularly prone to charring a third possibility is that the carbonised component of peat may be concentrated during coalification so that tertiary coals generally of lower rank than mesozoic or paleozoic coals contain a smaller fraction of carbonised plant material it is not at present clear which of these mechanisms may have affected carbonised material in peat and coal but it is clear that lignin type and content has had an important role in determining peat and coal character since the paleozoic

snow avalanche formation 1 snow avalanches are a major natural hazard endangering human life and infrastructure in mountainous areas throughout the world in many countries with seasonally snow covered mountains avalanche forecasting services reliably warn the public by issuing occurrence probabilities for a certain region however at present a single avalanche event cannot be predicted in time and space much about the release process remains unknown mainly because of the highly variable layered character of the snowpack a highly porous material that exists close to its melting point the complex interaction between terrain snowpack and meteorological conditions leading to avalanche release is commonly described as avalanche formation it is relevant to hazard mapping and essential to short term forecasting which involves weighting many contributory factors alternatively the release process can be studied and modeled this approach relies heavily on snow mechanics and snow properties including texture while the effect of meteorological conditions or changes on the deformational behavior of snow is known in qualitative or semiquantitative manner the knowledge of the quantitative relation between snow texture and mechanical properties is limited but promising developments are under way fracture mechanical models have been applied to explain the fracture propagation and micromechanical models including the two competing processes damage and sintering have been applied to explain snow failure there are knowledge gaps between the sequence of processes that lead to the release of the snow slab snow deformation and failure damage accumulation fracture initiation and fracture propagation simultaneously the spatial variability that affects damage fracture initiation and fracture propagation has to be considered this review focuses on dry snow slab avalanches and shows that dealing with a highly porous media close to its melting point and processes covering several orders of scale from the size of a bond between snow grains to the size of a mountain slope will continue to be very challenging

analysis and forecast of extreme new snow avalanches a numerical study of the avalanche cycles of february 1999 in france snow and weather conditions typical of exceptional cycles of fresh snow avalanches in the northern alps are investigated using the numerical avalanche hazard forecasting procedure of meteo france sensitivity tests are performed on the events of february 1999 in the chamonix france region and resulting snowpack instability modeled at the massif scale is compared using adapted new indices and maps our results complete conclusions of earlier observation based studies by providing new insights into the snow and weather conditions of february 1999 the large avalanches mainly resulted from large and very unstable fresh snow accumulations moreover the snowpack instability was increased locally by wind transport of light and fresh snow in february the mechanical weaknesses resulting from the weather conditions prior to february were a key factor in explaining the unusual volumes of these avalanches this study suggests that the operational numerical safran crocus mepra scm chain provides reliable forecasts of extreme new snow avalanche situations at the massif scale but that local scale simulations are still needed to improve the efficiency of risk mitigation and civil protection policies

a numerical model to simulate snow cover stratigraphy for operational avalanche forecasting laws of snow metamorphism have been introduced in a numerical model which simulates the evolution of temperature density and liquid water profiles of snow cover as a function of weather conditions to establish these laws the authors have summarized previous studies on temperature gradient and on wet snow metamorphism and they have also conducted metamorphism experiments on dry or wet fresh snow samples an original formalism was developed to allow a description of snow with parameters evolving continuously throughout time the introduction of laws of metamorphism has improved significantly the derivation of the settlement of internal layers and of snow covered albedo which depend on the simulated stratigraphy i e the type and size of snow grains of different layers of the snow cover the model was tested during a whole winter season without any re initialization comparison between the simulated characteristics of the snow cover and the observations made in the field are described in detail the model proved itself to be very efficient in simulating accurately the evolution of the snow cover stratigraphy throughout the whole winter season

the pliensbachian toarcian paleoclimate transition new insights from organic geochemistry and c h n isotopes in a continental section from central asia the taskomirsay section south kazakhstan is a unique pliensbachian toarcian sequence of lignites clayey layers and silty sandstones deposited in a fluvial lacustrine environment with nearby swampy areas this period characterized by a drastic climate change has been particularly studied in western tethyan marine environments whereas very few studies focused on continental settings paleoflora analyses associated with a multi isotope approach based on well preserved type iii bulk organic nitrogen isotopes a15norg and hydrogen isotopic composition a2h of n alkanes were developed to document paleoclimatic changes in the area sporomorph associations and fossil woods revealed a globally warm to cool temperate climate characterized by xenoxylon a conifer morphogenus biogeographically related to cool humid settings apart from slightly less humid and warmer conditions in the early toarcian warmer conditions are supported by reconstructed mean annual air temperatures maats based on the first branched glycerol dialkyl glycerol tetraethers brgdgts ever recorded in the early jurassic nevertheless no drastic changes were recorded in the a15norg values its signal being attributed to tenuous equilibrium between water and nutrient availability via intense n recycling based on n alkane distributions sources of organic matter were separated in two pools i a purely terrestrial n c27 and ii an aquatic pool n c23 constituted of vegetation that thrived under almost permanent water supply the n alkane a 2h values 248 to 151 as well as their amounts and average chain lengths acl are in agreement with cool temperate conditions in the pliensbachian and less humid warmer conditions in the early toarcian the isotopic difference between a2h values of n c27 and n c23 2hter aq suggests enhanced seasonality during the pliensbachian toarcian transition and low seasonality in the early toarcian in agreement with temperate climate regime finally contrasted response to paleoclimate changes between markers suggests different spatial integration of those proxies the role of sea level variations for a2h values might also resolve this contrasted response

spatio temporal reconstruction of snow avalanche activity using tree rings pierres jean jeanne avalanche talus massif de l oisans france snow avalanches are a major threat in many parts of the alps where they periodically damage infrastructure disrupt transportation corridors or even cause loss of life nonetheless the spatial behavior of past avalanche activity and the analysis of areas affected during particular events remain often imprecise it was therefore the purpose of this study to reconstruct spatio temporal patterns of past avalanche activity on a forested avalanche talus in the french alps pierres jean jeanne talus massif de l oisans france a total of 232 european larches larix decidua mill with clear signs of snow wasting events was analyzed and growth disturbances gd related to avalanche activity was assessed such as tangential rows of traumatic resin ducts the onset of compression wood or abrupt growth suppression and release in total 901 gd were identified in the tree ring samples indicating that 20 high magnitude avalanches occurred between ad 1919 and 1994 the mean return period of snow avalanches was 4 years with a 26 probability that an avalanche occurs in any particular year interpolated maps allowed for explicit spatial estimates of return periods throughout the talus showing a rapid increase of return frequency from 2 5 to 50 years with increasing distance from the talus apex the distribution of avalanche years seems to be quite homogeneous in time with a gap between 1951 and 1959 snowfall from a nearby meteorological station saint christophe en oisans 10 km from the study site indicated that the five most recent high magnitude events on record occurred due to above average snowfall anomalies in december and january associated with abnormally low air temperatures findings suggest that a strong snow metamorphism under high temperature gradients in january could explain the occurrence of high magnitude snow avalanches 2010 elsevier b v all rights reserved

statistical forecasting of regional avalanche danger using simulated snow cover data in the past numerical prediction of regional avalanche danger using statistical methods with meteorological input variables has shown insufficiently accurate results possibly due to the lack of snow stratigraphy data detailed snow cover data were rarely used because they were not readily available manual observations with the development and increasing use of snow cover models this deficiency can now be rectified and model output can be used as input for forecasting models we used the output of the physically based snow cover model snowpack combined with meteorological variables to investigate and establish a link to regional avalanche danger snow stratigraphy was simulated for the location of an automatic weather station near davos switzerland over nine winters only dry snow situations were considered a variety of selection algorithms was used to identify the most important simulated snow variables data mining and statistical methods including classification trees artificial neural networks support vector machines hidden markov models and nearest neighbour methods were trained on the forecasted regional avalanche danger european avalanche danger scale the best results were achieved with a nearest neighbour method which used the avalanche danger level of the previous day as additional input a cross validated accuracy hit rate of 73 was obtained this study suggests that modelled snow stratigraphy variables as provided by snowpack are able to improve numerical avalanche forecasting

controls on peat accumulation and depositional environments of a coal bearing coastal plain succession of a pull apart basin a petrographic geochemical and sedimentological study lower jurassic denmark abstract the paralic lower middle jurassic baga formation of the island of bornholm denmark was deposited in a fault bounded subsiding pull apart basin the formation is up to 400 m thick and contains more than 50 coal seams twelve of these have been investigated petrographically and geochemically to provide basic information on the composition of the relatively unknown jurassic coals the peat forming environments represented by the seams and the associated siliciclastic sediments are interpreted the seams represent three types of environments with organic matter deposition peat accumulation occurred in low lying areas situated between river channels in a coastal plain environment undergoing overall transgression the coals have a relatively uniform huminite rich petrographic composition indicating that the precursor mires were dominated by persistent water saturated and anoxic conditions the swamps were probably occupied by a small statured flora with cellulose rich tissues significant bacterial activity in the peat swamps is suggested by an abundance of hopanes influence from marine water was not common but occurred occasionally during peat accumulation the depositional conditions were stable and quiet the small thicknesses of the seams 8 57 cm thick indicate relatively short periods of peat formation average c 2300 yr due to continued base level rise controlled by subsidence and an overall eustatic rise causing repeated changes in the sedimentary regimes the coal seams are of low rank and were buried to a depth of 1100 1200 m before uplift due to late cretaceous early tertiary basin inversion and neogene uplift

an energy and mass model of snow cover suitable for operational avalanche forecasting a numerical model has been developed to simulate energy and mass evolution of snow cover at a given location as a function of meteorological conditions precipitation air temperature humidity wind velocity and incoming short wave and long wave radiation this model named crocus was first tested on a well instrumented field during a whole winter showing its ability to simulate the important phenomena affecting the evolution of the snow layers high temperature gradients wetting compaction and melting freezing cycles a second test was conducted at two locations in the french network used for operational avalanche forecasting though the weather observations are made there only twice daily the snow profiles calculated by the model were very close to those obtained once a week by a pit observation crocus proved itself sufficient to be considered now as a useful objective tool for operational avalanche forecasting

peat forming materials and evolution of swamp sequences case analysis of a jurassic inland coal basin in china abstract a case analysis was conducted in the yima coal mine which is located in a jurassic inland basin located in the henan province of central china using data from palynological ecology plant residues coal petrography and some geochemical characteristics the plant community during this coal forming period and the precursors of the coal forming peat were determined the peat forming paleoenvironment and evolutionary sequences within the swamp were reconstructed according to the differences in the spore pollen complex of the coals in the yima mine seven kinds of palynofacies each characterized by predominant species occured within the relative beds seven different types of ecological characteristics are indicated the different stages are represented by the corresponding floral facies six diagnostic properties of the coal facies were determined by studying the petrographic characteristics of each coal and seven different kinds of ancient peat forming swamp paleoenvironments are indicated by the coal facies a genetic model of formation development and evolutionary sequences of the coal forming swamp in the jurassic of central china is proposed

a new hierarchical bayesian approach to analyse environmental and climatic influences on debris flow occurrence abstract how can debris flow occurrences be modelled at regional scale and take both environmental and climatic conditions into account and of the two which has the most influence on debris flow activity in this paper we try to answer these questions with an innovative bayesian hierarchical probabilistic model that simultaneously accounts for how debris flows respond to environmental and climatic variables in it full decomposition of space and time effects in occurrence probabilities is assumed revealing an environmental and a climatic trend shared by all years catchments respectively clearly distinguished from residual random effects the resulting regional and annual occurrence probabilities evaluated as functions of the covariates make it possible to weight the respective contribution of the different terms and more generally to check the model performances at different spatio temporal scales after suitable validation the model can be used to make predictions at undocumented sites and could be used in further studies for predictions under future climate conditions also the bayesian paradigm easily copes with missing data thus making it possible to account for events that may have been missed during surveys as a case study we extract 124 debris flow event triggered between 1970 and 2005 in 27 catchments located in the french alps from the french national natural hazard survey and model their variability of occurrence considering environmental and climatic predictors at the same time we document the environmental characteristics of each debris flow catchment morphometry lithology land cover and the presence of permafrost we also compute 15 climate variables including mean temperature and precipitation between may and october and the number of rainy days with daily cumulative rainfall greater than 10 15 20 25 30 40 mm day 1 application of our model shows that the combination of environmental and climatic predictors explained 77 of the overall variability of debris flow occurrences in this data set occurrence probabilities depend mainly on climatic variables which explain 44 of the overall variability through the number of rainy days and maximum daily temperature this important time component in the variability of overall debris flow occurrence is shown to be responsible for a significant increase in debris flow activity between 1970 and 2005 at regional scale environmental variables which account for 33 of the overall variability includes mostly the morphometric variables of the debris flow catchments

solute release and sediment entrainment on microcatchments in the dinosaur park badlands alberta canada abstract this paper first considers the uptake of solutes and entrainment of sediments in runoff generated by simulated rainstorms on different badland surfaces then properties of the regolith materials related to solute uptake are described and studied in a number of simple laboratory experiments field and laboratory results are in close agreement runoff solute and sediment uptake are profoundly influenced by the large amounts of sodium montmorillonite present in the regolith shale surfaces although responding late to rainfall release increasing amounts of sediment and solutes sodium and sulphate as they swell and increase in erodibility on other surfaces low rates of rainfall acceptance are caused by the secretion of montmorillonite gels and there is a gradual decrease in solute and sediment concentration as accumulated salts are flushed from the surface the effect of the chemistry of the simulated rainfall on the experimental results is examined it is considered possible to characterize the pattern of solute and sediment uptake on the different badland surfaces and to apply this information to the identification of runoff sources in mesoscale drainage basins and to the routing of storm runoff

continuous snowpack monitoring using upward looking ground penetrating radar technology snow stratigraphy and water percolation are key contributing factors to avalanche formation so far only destructive methods can provide this kind of information radar technology allows continuous non destructive scanning of the snowpack so that the temporal evolution of internal properties can be followed we installed an upward looking ground penetrating radar system upgpr at the weissfluhjoch study site davos switzerland during two winter seasons 2010 11 and 2011 12 we recorded data with the aim of quantitatively determining snowpack properties and their temporal evolution we automatically derived the snow height with an accuracy of about 5 cm tracked the settlement of internal layers 7 cm and measured the amount of new snow 10 cm using external snow height measurements we determined the bulk density with a mean error of 4 3 compared to manual measurements radar derived snow water equivalent deviated from manual measurements by 5 furthermore we tracked the location of the dry to wet transition in the snowpack until water percolated to the ground based on the transition and an independent snow height measurement it was possible to estimate the volumetric liquid water content and its temporal evolution even though we need additional information to derive some of the snow properties our results show that it is possible to quantitatively derive snow properties with upgpr

a synthetic study to assess the applicability of full waveform inversion to infer snow stratigraphy from upward looking ground penetrating radar data snow stratigraphy and liquid water content are key contributing factors to avalanche formation upward looking groundpenetrating radar upgpr systems allow nondestructive monitoring of the snowpack but deriving density and liquid water content profiles is not yet possible based on the direct analysis of the reflection response we have investigated the feasibility of deducing these quantities using full waveform inversion fwi techniques applied to upgpr data for that purpose we have developed a frequency domain fwi algorithm in which we additionally took advantage of time domain features such as the arrival times of reflected waves our results indicated that fwi applied to upgpr data is generally feasible more specifically we could show that in the case of a dry snowpack it is possible to derive snow densities and layer thicknesses if sufficient a priori information is available in case of a wet snowpack in which it also needs to be inverted for the liquid water content the algorithm might fail even if sufficient a priori information is available particularly in the presence of realistic noise finally we have investigated the capability of fwi to resolve thin layers that play a key role in snow stability evaluation our simulations indicate that layers with thicknesses well below the gpr wavelengths can be identified but in the presence of significant liquid water the thin layer properties may be prone to inaccuracies these results are encouraging and motivate applications to field data but significant issues remain to be resolved such as the determination of the generally unknown upgpr source function and identifying the optimal number of layers in the inversion models furthermore a relatively high level of prior knowledge is required to let the algorithm converge however we feel these are not insurmountable and the new technology has significant potential to improve field data analysis