glaciers and rock glaciers distribution at 28 sl dry andes of argentina and some considerations about their hydrological significance the area studied includes a little known portion on the dry andes of the san juan frontal cordillera argentina where the hydrological significance of glaciers and rock glaciers was earlier never studied the surveyed sector includes cerro el potro 5 870 m asl and nearby mountain chains 28 s the predominant landforms in these areas were shaped in a periglacial environment superimposed on an earlier glacial landscape these regions comprise abundant rock glaciers a noteworthy rock glacier zone in the world of which little is known in south america this work employs geomorphological mapping to analyze the distribution of active rock glaciers in relation to altitude aspect and slope using optical remote sensing techniques with gis statistical estimation techniques were used based on a digital elevation model dem and aerial photos and spot images interpretation the specific density of rock glaciers estimation in the surveyed area argentine border is 1 56 with corresponds to 38 rock glaciers with an area of 5 86 km2 and 0 12 km3 of water equivalent furthermore the analytical results show that elevations 4 270 m asl a southeast facing aspect and slope between 2 and 40 favor the existence of rock glaciers finally a comparison with glacier water equivalent which covers an area of 16 km2 and 0 9 km3 of water equivalent shows that glaciers are the main stores of water at 28 s cerro el potro glacier however the importance of rock glaciers as water reserves in this portion of argentina should not be underestimated

permafrost activity and atmospheric warming in the argentinian andes abstract rock glaciers are permafrost or glacial landforms of debris and ice that deform under the influence of gravity recent estimates hold that in the semiarid chilean andes for example active rock glaciers store more water than glaciers however little is known about how many rock glaciers might decay because of global warming and how much this decay might contribute to water and sediment release we investigated an inventory of 6500 rock glaciers in the argentinian andes spanning the climatic gradient from the desert andes to cold temperate tierra del fuego we used active rock glaciers as a diagnostic of permafrost assuming that the toes mark the 0 c isotherm in climate scenarios for the twenty first century and their impact on freezing conditions near the rock glacier toes we find that under future worst case warming up to 95 of rock glaciers in the southern desert andes and in the central andes will rest in areas above 0 c and that this freezing level might move up more than twice as much 500 m as during the entire holocene 200 m many active rock glaciers are already well below the current freezing level and exemplify how local controls may confound regional prognoses a bayesian multifactor analysis of variance further shows that only in the central andes are the toes of active rock glaciers credibly higher than those of inactive ones elsewhere in the andes active and inactive rock glaciers occupy indistinguishable elevation bands regardless of aspect the formation mechanism or shape of rock glaciers the state of rock glacier activity predicts differences in elevations of toes to 140 m at best so that regional inference of the distribution of discontinuous permafrost from rock glacier toes cannot be more accurate than this in the argentinian andes we conclude that the central andes where rock glaciers are largest cover the most area and have a greater density than glaciers is likely to experience the most widespread disturbance to the thermal regime of the twenty first century

late pleistocene and holocene activity of the atacazo ninahuilca volcanic complex ecuador abstract the atacazo ninahuilca volcanic complex anvc is located in the western cordillera of ecuador 10 km southwest of quito at least six periods of pleistocene to holocene activity n1 to n6 have been preserved in the geologic record as tephra fallouts and pyroclastic flow deposits new field data including petrographic and whole rock geochemical analyses of over forty soil and tephra sections 100 pumice and lithic samples and 10 new 14 c ages allow us to constrain 1 the tephra fall isopachs and detailed characteristics of the last two events n5 n6 including volume estimates of the tephra and pyroclastic flow deposits and the corresponding volcanic explosivity index vei 2 the petrographical and geochemical correlations between domes tephras and pyroclastic flow deposits and 3 the timing of the last 4 eruptive events and a period of quiescence that endured a few thousand years 1000 4000 the last two eruptive events n5 and n6 took place at around 4400 35 yr bp and 2270 15 yr bp producing huge plinian and pyroclastic flow deposits taking into account the widely spread deposits of these vei 5 eruptions the present population of about 70 000 people and the current infrastructure the development of mitigation plans and deployment of monitoring systems at anvc is highly recommended

instruments and methods geophysical imaging of alpine rock glaciers slope instabilities caused by the disappearance of ice within alpine rock glaciers are an issue of increasing concern design of suitable counter measures requires detailed knowledge of the internal structures of rock glaciers which can be obtained using geophysical methods we examine benefits and limitations of diffusive electromagnetics geoelectrics seismics and ground penetrating radar georadar for determining the depth and lateral variability of the active layer the distributions of ice and water the occurrence of shear horizons and the bedrock topography in particular we highlight new developments in data acquisition and data analysis that allow 2 d or even 3 d structures within rock glaciers to be imaged after describing peculiarities associated with acquiring appropriate geophysical datasets across rock glaciers and emphasizing the importance of state of the art tomographic inversion algorithms we demonstrate the applicability of 2 d imaging techniques using two case studies of rock glaciers in the eastern swiss alps we present joint interpretations of geoelectric seismic and georadar data appropriately constrained by information extracted from boreholes a key conclusion of our study is that the different geophysical images are largely complementary with each image resolving a different suite of subsurface features based on our results we propose a general template for the cost effective and reliable geophysical characterization of mountain permafrost

rock glaciers and mountain hydrology a review abstract in mountainous regions climate change threatens cryospheric water resources and understanding all components of the hydrological cycle is necessary for effective water resource management rock glaciers are climatically more resilient than glaciers and contain potentially hydrologically valuable ice volumes and yet have received less attention even though rock glacier hydrological importance may increase under future climate warming in synthesising data from a range of global studies we provide the first comprehensive evaluation of the hydrological role played by rock glaciers we evaluate hydrological significance over a range of temporal and spatial scales alongside the complex multiple hydrological processes with which rock glaciers can interact diurnally seasonally annually decadally and both at local and regional extents we report that although no global extent complete inventory for rock glaciers exists currently recent research efforts have greatly elaborated spatial coverage using these research papers we synthesise information on rock glacier spatial distribution morphometric characteristics surface and subsurface features ice storage and hydrological flow dynamics water chemistry and future resilience from which we provide the first comprehensive evaluation of their hydrological contribution we identify and discuss long intermediate and short term timescales for rock glacier storage allowing a more balanced assessment of the contrasting perspectives regarding the relative significance of rock glacier derived hydrological contributions compared to other water sources we show that further empirical observations are required to gain a deeper hydrological understanding of rock glaciers in terms of i their genesis and geomorphological dynamics ii total ice water volume iii water discharge and iv water quality lastly we hypothesise that at decadal and longer timescales under future climate warming degradation of ice within rock glaciers may represent an increasing hydrological contribution to downstream regions and thus increased hydrological significance while rock glacier water stores persist

geophysical imaging of alpine rock glaciers slope instabilities caused by the disappearance of ice within alpine rock glaciers are an issue of increasing concern design of suitable counter measures requires detailed knowledge of the internal structures of rock glaciers which can be obtained using geophysical methods we examine benefits and limitations of diffusive electromagnetics geoelectrics seismics and ground penetrating radar georadar for determining the depth and lateral variability of the active layer the distributions of ice and water the occurrence of shear horizons and the bedrock topography in particular we highlight new developments in data acquisition and data analysis that allow 2 d or even 3 d structures within rock glaciers to be imaged after describing peculiarities associated with acquiring appropriate geophysical datasets across rock glaciers and emphasizing the importance of state of the art tomographic inversion algorithms we demonstrate the applicability of 2 d imaging techniques using two case studies of rock glaciers in the eastern swiss alps we present joint interpretations of geoelectric seismic and georadar data appropriately constrained by information extracted from boreholes a key conclusion of our study is that the different geophysical images are largely complementary with each image resolving a different suite of subsurface features based on our results we propose a general template for the cost effective and reliable geophysical characterization of mountain permafrost

synergistic approach for mapping debris covered glaciers using optical thermal remote sensing data with inputs from geomorphometric parameters abstract debris cover on glacier boundaries critically impedes the global inventorying of glaciers and confounds most of the techniques developed for semi automated mapping of glaciers debris on the glacier referred as supraglacial debris and that occurring outside the glacier boundaries referred as periglacial debris being derived from a common source i e the valley rock tend to have a similar spectral response in the reflection region which renders them mutually indistinguishable however there exist temperature differences between them this aspect has been considered in this remote sensing based study to distinguish between the supraglacial and periglacial debris in a test area in the chenab basin himalayas by inclusion of thermal infrared tir bands in remote sensing data processing a synergistic multisensor approach for the delineation of debris covered glacier boundaries is used here which integrates the inputs from thermal terra aster sensor and optical irs p6 awifs sensor remote sensing data multispectral classification techniques and the dem derived geomorphometric parameters the results of this study corroborate earlier findings on utilization of temperature differences as one of the parameters in glacial studies the proposed synergistic approach therefore appears useful in accurate mapping of debris covered glaciers in the himalayan region

a regional inventory of rock glaciers and protalus ramparts in the central italian alps abstract we present a regional inventory of rock glaciers n 1514 and protalus ramparts 228 for the lombardy region central italian alps to identify and classify the landforms we inspect three sequential air orthophoto mosaics and a 2 m dsm and conduct confirmatory field work the inventory forms an empirical basis to analyze i the relative contribution of hillslope i e talus slopes and glacial i e moraines sediment stores to rock glacier sediment supply ii linkages between the landforms inventoried and local topographic attributes iii the spatial variability of periglacial activity in relation to a parsimonious set of environmental variables i e elevation precipitation and lithology and iv the effects of the pleistocene holocene climatic transition on the distribution of intact and relict landforms this analysis reveals that the elevation of rock glacier termini can vary over 200 m as a function of slope aspect in turn the distribution of rock glaciers among aspect categories is controlled by the structure of the valley network that promotes nw and se exposures talus rock glaciers prevail numerically over the glacier related typology even though the latter population appears to have increased during the holocene relict and intact rock glaciers have distinct spatial patterns in that the former display on average a 400 m elevation drop and a less clustered distribution towards northern aspects suggesting that they have developed in more permafrost prone climatic conditions analyzing the study region through a 27 5 km grid has been instrumental for showing that the rock glacier specific area and terminus elevation are i positively correlated with terrain elevation and ii negatively correlated with mean annual precipitation as a consequence in relation to holocene generalized atmospheric temperature rise intact rock glaciers have progressively disappeared from the wetter and milder portions of the central italian alps analysis of rock glacier occurrence across litho tectonic sectors does not provide conclusive dependences and requires further analysis this inventory which represents a necessary preliminary step for modelling the spatial distribution of discontinuous permafrost at the regional scale fills a critical geographic gap in the context of ongoing permafrost research in the european alps e g permanet

glacier recession and water resources in peru s cordillera blanca the tropical glaciers of the cordillera blanca peru are rapidly retreating resulting in complex impacts on the hydrology of the upper rio santa watershed the effect of this retreat on water resources is evaluated by analyzing historical and recent time series of daily discharge at nine measurement points using the mann kendall nonparametric statistical test the significance of trends in three hydrograph parameters was studied results are interpreted using synthetic time series generated from a hydrologic model that calculates hydrographs based on glacier retreat sequences the results suggest that seven of the nine study watersheds have probably crossed a critical transition point and now exhibit decreasing dry season discharge our results suggest also that once the glaciers completely melt annual discharge will be lower than present by 2 30 depending on the watershed the retreat influence on discharge will be more pronounced during the dry season than at other periods of the year at la balsa which measures discharge from the upper rio santa the glacier retreat could lead to a decrease in dry season average discharge of 30

classification of debris covered glaciers and rock glaciers in the andes of central chile in the dry andes of chile 17 to 35 s debris covered glaciers and rock glaciers are differentiated from true glaciers based on the percentage of surface debris cover thickness of surface debris and ice content internal ice is preserved by an insulating cover of thick debris which acts as a storage reservoir to release water during the summer and early fall these landforms are more numerous than glaciers in the central andes however the existing legislation only recognizes uncovered or semicovered glaciers as a water resource glaciers debris covered glaciers and rock glaciers are being altered or removed by mining operations to extract valuable minerals from the mountains in addition agricultural expansion and population growth in this region have placed additional demands on water resources in a warmer climate as glaciers recede and seasonal water availability becomes condensed over the course of a snowmelt season rock glaciers and debris covered glaciers contribute a larger component of base flow to rivers and streams as a result identifying and locating these features to implement sustainable regional planning for water resources is important the objective of this study is to develop a classification system to identify debris covered glaciers and rock glaciers based on the interpretation of satellite imagery and aerial photographs the classification system is linked to field observations and measurements of ice content debris covered glaciers have three subclasses surface coverage of semi class 1 and fully covered class 2 glaciers differentiates the first two forms whereas debris thickness is critical for class 3 when glaciers become buried with more than 3 m of surface debris based on field observations the amount of ice decreases from more than 85 to 65 85 to 45 65 for semi fully and buried debris covered glaciers respectively rock glaciers are characterized by three stages class 4 rock glaciers have pronounced transverse ridges and furrows that arch across the surface which indicates flow produced via ice class 5 rock glaciers have ridges and furrows that appear linear in the direction of flow indicating reduced flow from limited internal ice and class 6 rock glaciers have subdued surface topography because the movement of the rock glacier has ceased ice content decreases from 25 45 to 10 25 to 10 from class 4 to 6 respectively examples from digital imagery aerial photographs and field photographs are provided for each class the classification scheme can be used to identify and map debris covered glaciers and rock glaciers to create an inventory this will help improve recognition of these landforms as an important water resource in the dry andes of chile which will aid in sustainable planning and development in basins that hold the majority of the population and support a large share of the economic activity in chile

do debris covered glaciers demonstrate distinctive hydrological behaviour compared to clean glaciers abstract supraglacial debris is known to strongly influence the distribution of glacier surface melt since melt inputs drive the formation and evolution of glacial drainage systems it should follow that the drainage systems of debris covered glaciers will differ from those of debris free glaciers this would have implications for the proglacial runoff regime subglacial erosion and glacier dynamics this paper presents analysis of return curves from 33 successful dye injections into the extensively debris covered miage glacier italian alps it demonstrates that the spatial distribution of supraglacial debris influences the structure and seasonal evolution of the glacial drainage system where the debris cover is continuous melt is lower and the surface topography is chaotic with many small supraglacial catchments these factors result in an inefficient englacial subglacial drainage network beneath continuous debris which drains to the conduit system emanating from the upper ablation zone melt rates are high in areas of clean and dirty ice above the continuous debris runoff from these areas is concentrated by inter moraine troughs into large supraglacial streams which encourages the early season development of an efficient englacial subglacial conduit system downstream of this area drainage efficiency from the debris covered area increases over the melt season but dye trace transit velocity remains lower than from moulins on the upper glacier future runoff models should account for the influence of supraglacial debris on the hydrological system

an inventory and estimate of water stored in firn fields glaciers debris covered glaciers and rock glaciers in the aconcagua river basin chile abstract an inventory of firn fields glaciers debris covered glaciers and rock glaciers was conducted in the aconcagua river basin of the semiarid andes of central chile a total of 916 landforms were identified of which rock glaciers were the most abundant 669 and occupied the most total area glaciers and debris covered glaciers were less numerous but were about five times larger in comparison the total area occupied by glaciers and debris covered glaciers was roughly equivalent to the total area of rock glaciers debris covered glaciers and rock glaciers were subcategorized into six ice content classes based on interpretation of surface morphology with high resolution satellite imagery over 50 of rock glaciers fell within a transitional stage 85 of debris covered glaciers were either fully covered or buried most landforms occupied elevations between 3500 and 4500 m glaciers and firn occurred at higher elevations compared to rock glaciers and debris covered glaciers rock glaciers had a greater frequency in the northern part of the study area where arid climate conditions exist firn and glaciers were oriented south debris covered glaciers west and rock glaciers southwest an analysis of water contribution of each landform in the upper andes of the aconcagua river basin was conducted using formulas that associate the size of the landforms to estimates of water stored minimum and maximum water storage was calculated based on a range of debris to ice content ratios for debris covered glaciers and rock glaciers in the aconcagua river basin rock glaciers accounted for 48 to 64 of the water stored within the landforms analyzed glaciers accounted for 15 to 25 debris covered glaciers were estimated at 15 to 19 firn fields contained only about 5 to 8 of the water stored expansion of agriculture prolonged drought and removal of ice rich landforms for mining have put additional pressure on already scarce water resources to develop long term sustainable solutions the importance of the water stored in rock glaciers or other alpine permafrost landforms such as talus slopes must be weighed against the economic value of mineral resources

status and evolution of the cryosphere in the andes of santiago chile 33 5 s in the context of a general retreat of glaciers in the dry andes this study focuses on the state and recent evolution of debris covered glaciers and permafrost related landforms especially rock glaciers in the semiarid to semihumid laguna negra catchment a part of the andes of central chile at 33 5 s that is a key contributor of drinking water for the city of santiago we conducted catchment scale geomorphological mapping diachronic analysis of 1955 and 1996 orthophotographs and digital elevation models dems and the analysis of ground temperatures and their sensitivity to climate variation rock glaciers dominate spatially and in terms of water storage over glaciers area ratio 1 7 1 ratio of water equivalents 1 5 1 an intense downwasting has affected both debris covered and exposed glacier components in the punta negra subcatchment a process that is associated with the growth of numerous thermokarst depressions the altitudinal transect of ground temperature suggest that permafrost is widespread above 4000 m asl although it can also occur at lower elevations on sheltered footslopes and within rock glaciers the sensitivity analysis indicates that the near surface ground thermal regime at high altitudes is strongly influenced by the snow cover disappearance date which may therefore constitute an important control on the effect of climatic warming

flow and internal structure of a rock glacier exposure of a full transverse cross section of the terminus of fireweed rock glacier wrangell mountains alaska revealed a thin layer of unconsolidated debris mantling a consolidated melange of ice and rock the main rock glacier is fed by three tributaties at the terminus contacts between the three are sharply defined ice content is 50 by volume bubble foliation and crystal morphologies of the ice matrix are similar to those reported from glacier ice folded ice rich strata and lenses foliation planes and the long intermediate axial planes of tabular shaped englacial clasts dip steeply toward the center line of the rock glacier the planar structures generally parallel the steep walls of the gorge containing the trunk stream these steeply dipping longitudinal structures appear to result from transverse compression where the tributaries converge and the trunk stream narrows down valley bergschrund like and moulin like features at the heads of the middle and west tributaries respectively exposed admixed ice and rock similar to that of the terminus but lacking the well developed flow texture talus from the unstable cirque headwall and polygeneticice both accumulate at the base of the headwall and nourrish the tributary rock glaciers

ba ca variations in the modern intertidal bean clam donax gouldii an upwelling proxy abstract the discovery and calibration of high resolution paleoceanographic proxies is necessary to extend historic climate records and to understand regional climate variability chemical variations of skeletal remains have emerged as an often reliable recorder of environmental conditions specifically ba ca ratios have been correlated to temperature salinity seawater ba ca and phytoplankton biomass although many of these relationships appear taxon and location specific to assess the sub weekly ba ca variations in the intertidal shallow burrowing bivalve donax gouldii specimens were collected from the southern california bight skeletal growth increments were cross dated based on tidal driven growth patterns and skeletal aragonite ba ca was determined using laser ablation inductively coupled plasma mass spectrometry cross dated growth among specimens revealed a simultaneous large and transient ba ca peak in all shells the timing of peak ba ca was compared to a suite of locally measured physical and biological data including temperature salinity density nitrate silicate chlorophyll diatom abundance dinoflagellate abundance and phytoplankton community composition based on cross dated chronologies ba cashell is significantly correlated with chl a from six and nine days prior and nutrients nitrate phosphate silicate and nitrite from three days prior in this system diatom abundance was not related to ba cashell transiently higher seawater ba ca resulting from upwelling may be reflected in peak ba cashell however the exact mechanisms leading to population wide ba ca peaks remains enigmatic

mechanisms linking active rock glaciers and impounded surface water formation in high mountain areas rock glaciers are slowly flowing mixtures of debris and ice occurring in mountains they can represent a reservoir of water and melting ice inside them can affect surface water hydrochemistry investigating the interactions between rock glaciers and water bodies is therefore necessary to better understand these mechanisms with this goal we elucidate the hydrology and structural setting of a rock glacier marginal pond system providing new insights into the mechanisms linking active rock glaciers and impounded surface waters this was achieved through the integration of waterborne geophysical techniques ground penetrating radar electrical resistivity tomography and self potentials and heat tracing results of these surveys showed that rock glacier advance has progressively filled the valley depression where the pond is located creating a dam that could have modified the level of impounded water a sub surface hydrological window connecting the rock glacier to the pond was also detected where an inflow of cold and mineralised underground waters from the rock glacier was observed here greater water contribution from the rock glacier occurred following intense precipitation events during the ice free season with concomitant increasing electrical conductivity values the outflowing dynamic of the pond is dominated by a sub surface seepage where a minor fault zone in bedrock was found characterised by altered and highly fractured rocks the applied approach is evaluated here as a suitable technique for investigating logistically complex hydrological settings which could be possibly transferred to wider scales of investigation

glaciation of alpine valleys the glacier debris covered glacier rock glacier continuum abstract alpine ice varies from pure ice glaciers to partially debris covered glaciers to rock glaciers as defined by the degree of debris cover in many low to mid latitude mountain ranges the few bare ice glaciers that do exist in the present climate are small and are found where snow is focused by avalanches and where direct exposure to radiation is minimized instead valley heads are more likely to be populated by rock glaciers which can number in the hundreds these rock cloaked glaciers represent some of the most identifiable components of the cryosphere today in low to mid latitude settings and the over steepened snouts pose an often overlooked hazard to travel in alpine terrain geomorphically rock glaciers serve as conveyor belts atop which rock is pulled away from the base of cliffs in this work we show how rock glaciers can be treated as an end member case that is captured in numerical models of glaciers that include ice dynamics debris dynamics and the feedbacks between them specifically we focus on the transition from debris covered glaciers where the modern equilibrium line altitude ela intersects the topography to rock glaciers where the modern ela lies above the topography on debris covered glaciers i e glaciers with a partial rock mantle rock delivered to the glacier from its headwall or from sidewall debris swept into the glacier at tributary junctions travels englacially to emerge below the ela there it accumulates on the surface and damps the rate of melt of underlying ice this allows the termini of debris covered glaciers to extend beyond debris free counterparts thereby decreasing the ratio of accumulation area to total area of the glacier aar in contrast rock glaciers i e glaciers with a full rock mantle occur where and when the environmental ela rises above the topography they require avalanches and rockfall from steep headwalls the occurrence of rock glaciers reflects this dependence on avalanche sources because they are most common on lee sides of ridges and peaks where wind blown snow enhances the strength of the avalanche source to maintain positive mass balance the avalanche cone developed in the winter must be sufficiently thick not to melt entirely in the summer thus providing an ice accumulation area for the rock glacier in the absence of rockfall this would support a short cirque glacier the presence of debris however facilitates the development of rock glaciers with lengths of hundreds of meters thicknesses of tens of meters and speeds of meters per year that are well described by numerical models numerical models are used to explore the alpine glacier response to its climate history in warming climates a debris covered glacier can transform into a much shorter rock glacier leaving in its wake a thinning ice cored moraine rock glaciers will persist in landscapes well beyond debris free counterparts because they have much longer response times to climate change the headwaters of alpine basins with steep headwalls will therefore oscillate between glacier and rock glacier occupation over glacial interglacial cycles maintaining a means by which rock from the headwall can be conveyed away this enhances the asymmetry of alpine ridgelines with downwind valleys biting deeply into the range crests as originally noted by g k gilbert

the effect of topography latitude and lithology on rock glacier distribution in the lemhi range central idaho usa abstract statistical analysis of rock glaciers in the lemhi range demonstrates that their development and preservation is controlled primarily by annual insolation and lithology we inspected 171 alpine valleys in the lemhi range using optical remote sensing techniques digital topographic analysis and field examination in those valleys we identified 48 rock glaciers and examined them for lichen cover evidence of ice presence specific evidence of movement and distinctive morphological features in addition to recording the presence or absence of a rock glacier in each alpine valley existing rock glaciers were classified according to their morphology factors such as topographic shading lithology relief aspect and elevation determine the development and preservation of rock glaciers analysis of these factors in the lemhi range shows that elevation 2600 m a north facing aspect 300 60 and multivariate statistical analysis of controlling parameters demonstrates that annual insolation and latitude influence rock glacier occurrence most strongly whereas duration of insolation is a logical controlling factor latitude is more enigmatic additional statistical analysis indicates that the latitude factor is likely a reflection of lithologic changes with latitude along the range lithology may affect rock glacier distribution through its effects on hydrology or air ventilation moreover statistical analysis shows that rock glacier occurrence correlates with protalus lobe occurrence suggesting that protalus lobes play a role in the genesis of rock glaciers in the lemhi range separate analysis of the classification systems shows that each morphologic class inferred to correlate with rock glacier activity is statistically significant and distinguishable from other classes in addition to the effect of insolation statistical analysis of the classification system also shows that latitude influences distribution of existing rock glacier classes independent of lithology

new insights on permafrost genesis and conservation in talus slopes based on observations at fluelapass eastern switzerland abstract the talus slope at fluelapass was the first mountain permafrost study site in switzerland in the 1970s and the presence of ice rich permafrost at the foot of the slope has been investigated in the context of several studies focusing on the role of snow cover distribution we review previously developed hypotheses and present new ones using various data sources such as temperature measurements in boreholes a subaquatic dem generated from unmanned aerial system uas photogrammetry terrestrial laser scan measurements of snow depth geophysical ground investigations and automatic time lapse photography from this combination of data sources together with observations in the field an interesting sequence of geomorphologic processes is established at fluelapass as a result we show how mass wasting processes can initiate the genesis and long term conservation of ice rich permafrost at the base of a talus slope

the differing biogeochemical and microbial signatures of glaciers and rock glaciers glaciers and rock glaciers supply water and bioavailable nutrients to headwater mountain lakes and streams across all regions of the american west here we present a comparative study of the metal nutrient and microbial characteristics of glacial and rock glacial influence on headwater ecosystems in three mountain ranges of the contiguous u s the cascade mountains rocky mountains and sierra nevada several meltwater characteristics water temperature conductivity ph metals nutrients complexity of dissolved organic matter dom and bacterial richness and diversity differed significantly between glacier and rock glacier meltwaters while other characteristics ca fe sio2 concentrations reactive nitrogen and microbial processing of dom showed distinct trends between mountain ranges regardless of meltwater source some characteristics were affected both by glacier type and mountain range e g temperature ammonium nh4 and nitrate no3 concentrations and bacterial diversity due to the ubiquity of rock glaciers and the accelerating loss of the low latitude glaciers our results point to the important and changing influence that these frozen features place on headwater ecosystems

regional and global volumes of glaciers derived from statistical upscaling of glacier inventory data 1 very few global scale ice volume estimates are available for mountain glaciers and ice caps although such estimates are crucial for any attempts to project their contribution to sea level rise in the future we present a statistical method for deriving regional and global ice volumes from regional glacier area distributions and volume area scaling using glacier area data from 123 000 glaciers from a recently extended world glacier inventory we compute glacier volumes and their sea level equivalent sle for 19 glacierized regions containing all mountain glaciers and ice caps on earth on the basis of total glacierized area of 741 103 68 103 km2 we estimate a total ice volume of 241 103 29 103 km3 corresponding to 0 60 0 07 m sle of which 32 is due to glaciers in greenland and antarctica apart from the ice sheets however our estimate is sensitive to assumptions on volume area scaling coefficients and glacier area distributions in the regions that are poorly inventoried i e antarctica north america greenland and patagonia this emphasizes the need for more volume observations especially of large glaciers and a more complete world glacier inventory in order to reduce uncertainties and to arrive at firmer volume estimates for all mountain glaciers and ice caps

mountain permafrost development and challenges of a young research field an overview is given of the relatively short history important issues and primary challenges of research on permafrost in cold mountain regions the systematic application of diverse approaches and technologies contributes to a rapidly growing knowledge base about the existence characteristics and evolution in time of perennially frozen ground at high altitudes and on steep slopes these approaches and technologies include 1 drilling borehole measurement geophysical sounding photogrammetry laser altimetry gps sar surveying and miniature temperature data logging in remote areas that are often difficult to access 2 laboratory investigations e g rheology and stability of ice rock mixtures 3 analyses of digital terrain information 4 numerical simulations e g subsurface thermal conditions under complex topography and 5 spatial models e g distribution of permafrost where surface and microclimatic conditions are highly variable spatially a sound knowledge base and improved understanding of governing processes are urgently needed to deal effectively with the consequences of climate change on the evolution of mountain landscapes and especially of steep mountain slope hazards as the stabilizing permafrost warms and degrades interactions between glaciers and permafrost in cold mountain regions have so far received comparatively little attention and need more systematic investigation

rockglacier activity studies on a regional scale comparison of geomorphological mapping and photogrammetric monitoring in their spatial distribution as well as in their different states of activity rockglaciers imply important information on former and recent permafrost conditions two different methods were applied in one study area turtmann valley swiss alps in order to compare their suitability in assessing rockglacier activity the comparison of geomorphological mapping and photogrammetric monitoring demonstrated a good accordance especially on a regional scale on a local scale some differences in delimitation of the landforms as well as in the degree of activity were found one reason for the observed differences is the qualitative character of geomorphological mapping resulting from the variable suitability of single parameters and combinations thereof in the determination of rockglacier activity based on these results geomorphological mapping of rockglaciers can be improved by data from photogrammetric monitoring therefore at best the two methods are combined when analysing former and present permafrost distribution copyright 2007 john wiley sons ltd

relict rock glaciers and protalus lobes in the british isles implications for late pleistocene mountain geomorphology and palaeoclimate many relict rock glaciers and protalus lobes have been described in mountainous areas of the british isles this paper reviews their distribution chronology supposed origin and development and places the research within current investigations and knowledge rock glaciers and protalus lobes are located in a number of different topographic locations and settings they developed at the base of steep cliffs following the catastrophic failure of rock faces at the base of scree slopes following the gradual accumulation of rock debris and in association with glaciers protalus lobes probably developed in response to the permafrost creep of talus material while rock glaciers formed through the deformation and sliding of large bodies of buried ice rock glaciers probably developed or were last active during the younger dryas although the possibility exists that some of these landforms are dimlington stadial in age the development of protalus lobes during the younger dryas suggests that precipitation levels were low and permafrost was widespread during this time the lack of rock glaciers sensu stricto in the british isles compared with other mountain areas is believed to be a consequence of the rock type and relative scarcity of weathered debris for their formation rather than a lack of suitable sites or appropriate environmental conditions copyright 2007 john wiley sons ltd

climate sensitivity implications for the response of geomorphological systems to future climate change climate sensitivity is defined as the equilibrium temperature response of the climate system to a doubling of atmospheric co2 levels from pre industrial levels despite three decades of debate in the climatological literature on the estimation and significance of climate sensitivity very little appears in the geomorphological literature on the implications of this for geomorphological systems this paper reviews the concept of climate sensitivity and applies its findings to an assessment of future landscape change in cold regions it is concluded that paraglacial processes will become the dominant mechanism of sediment transfer in currently glaciated catchments and that this period of sediment mobilization will be the last episode of major sediment movement for geological time periods there is a scientific consensus oreskes 2004 that the mean surface temperature of the earth has increased in recent decades and that the warming amounts to around 0 8 8c since the beginning of the twentieth century ipcc 2007 from this nasa goddard institute of space studies giss estimates that 2005 was the warmest year to date since reliable instrumental measurements become available although the world meteorological office wmo and climatic research unit cru place it just behind 1998 detection and attribution studies show that there is high probability at least 90 that this warming is largely the result of anthropogenic emissions of greenhouse gases ghg mainly co2 in the troposphere and that the amount and rate of warming lie outside of the range of natural variation and are unprecedented within the context of the holocene the last 11 000 years continued future warming is expected to have important consequences for a range of earth systems including the atmosphere cryosphere oceans hydrological systems and the biosphere and there are compelling reasons to expect increases in the magnitude and frequency of some natural hazards such as floods huntington 2006 droughts mason goddard 2001 and landslides e g fischer et al 2006 and increases in the intensity of tropical cyclones emanuel 2005 there are also concerns about the stability of several of the large ice sheets on earth e g overpeck et al 2006 as break up of these has the ability to impact upon global sea levels and regulate ocean currents given that climate is a major driver of many earth systems the rate nature and extent of future climate changes are important variables for understanding the future behaviour of geomorphological processes and the likely evolution of geomorphological systems as a result it is surprising that little appears in the geomorphological literature assessing climate sensitivity as a factor in landform and landscape evolution it is therefore the purpose of this paper to synthesize current understanding of climate sensitivity defined later and discuss briefly the implications of this for assessing the response of mountain geomorphological systems to future temperature rises metrics for climate change metrics are of interest to geomorphologists and other earth scientists modelling the response of earth systems to changes in climate as they provide a baseline measurement from which to calculate change the most widely used metric is the global mean surface temperature which is estimated by the hadcru hadley climatic research unit data set which excludes the polar regions or by the nasa giss assessment which extrapolates to the poles the warming of mean surface temperature is related theoretically and empirically to the idea of radiative forcing at the top of the atmosphere radiative forcing is measured in w m and can be defined as a measure of the influence a factor has in altering the balance of incoming and outgoing energy in the earth atmosphere system and is an index of the importance of the factor as a potential climate change mechanism ipcc 2001 despite this metric having been used by the ipcc assessment reports and adopted by from knight j harrison s eds periglacial and paraglacial processes and environments the geological society london special publications 320 257 265 doi 10 1144 sp320 16 0305 8719 09 15 00 the geological society publishing house 2009 policy makers there have been a number of challenges to its use the most credible challenge comes from the suggestion that a global heat budget measures the warming of the earth in a more complete way than the global mean surface temperature e g pielke 2003 in addition there are important uncertainties and limitations associated with the concept national academies of sciences 2005 especially as radiative forcing fails to account adequately with regional forcings such as by aerosols and land use changes that may have significant climatic effects at the local scale

the geomorphic significance of rock glaciers estimates of rock glacier debris volumes and headwall recession rates in west greenland to obtain knowledge on rockwall retreat rates at sites with rock glaciers an inventory of about 400 individual rock glacier sites in west greenland was carried out by means of field studies and using aerial photographs and topographic maps a number of sites with ice cored moraines beyond normal glaciers were included in the analysis for comparative purposes the estimated debris volume was compared with the size of the source headwall the result of the inventory suggests that the presence of rock glaciers indicates extraordinary high retreat rates for rock free faces above especially headwalls above glacier derived rock glaciers are exposed to high weathering rates and thereby presumably delimit critical ranges regarding altitude for headwall retreat rates the relation of such a critical altitudinal range to other regional concepts such as glaciation level gl and glacier equilibrium line is discussed from this comments are also made on the relation between various permafrost zones and the typical regional climate within the maximum headwall weathering altitude at sites with active rock glaciers finally the potential importance of this range of maximum weathering for understanding the long term evolution of high relief cold climate landscapes is emphasised

the significance of rock glaciers in the glacial periglacial landscape continuum rock glaciers are distinct landforms whose wide distribution occurrence and significance often go unrecognised they are deposits of poorly sorted angular blocky to tabular debris which are held together by an ice core or a matrix of ice cemented fine clastics rock glaciers have formed in glaciated and non glaciated areas many researchers have suggested that the absence of an ice core or the lack of movement indicates relict or fossil status active and inactive states can be viewed as the end members of a movement continuum movement rates derived from world wide locations as reported in the literature range from less than 1 cmyr 1 to greater than 130cmyr 1 unfortunately lack of observed movement has been equated incorrectly with an inactive status rock glacier movement must be considered from a rheological point of view movement is controlled by the transformation of potential energy to kinetic energy as the system attempts to reach thermal equilibrium or stability whereas a glacier can completely disappear or redevelop reactivation of a rock glacier requires only the re establishment of the conditions responsible for development and maintenance of interstitial ice although it might not be possible to re establish an ice core interstitial areas can definitely be recharged with ice and thus facilitate movement the concept of active versus inactive should be abandoned in favor of the view that a spatial and temporal continuum of form and movement exists

relationships between glacier and rock glacier in the maritime alps schiantala valley italy abstract in the schiantala valley of the maritime alps the relationship between a till like body and a contiguous rock glacier has been analyzed using geomorphologic geoelectric and ice petrographic methodologies dc resistivity tomographies undertaken in the till and in the rock glacier show the presence of buried massive ice and ice rich sediments respectively ice samples from a massive ice outcrop show spherical gas inclusions and equidimensional ice crystals that are randomly orientated confirming the typical petrographic characteristics of sedimentary ice the rock glacier formation began after a phase of glacier expansion about 2550 50 14c yr bp further ice advance during the little ice age lia overrode the rock glacier root and caused partial shrinkage of the pre existing permafrost finally during the 19th and 20th centuries the glacial surface became totally debris covered geomorphological and geophysical methods combined with analyses of ice structure and fabric can effectively interpret the genesis of landforms in an environment where glaciers and permafrost interact ice petrography proved especially useful for differentiating ice of past glaciers versus ice formed under permafrost conditions these two mechanisms of ice formation are common in the maritime alps where many sites of modern rock glaciers were formerly occupied by lia glaciers

prevention of outburst floods from periglacial lakes at grubengletscher valais swiss alps flood and debris flow hazards at grubengletscher near saas balen in the saas valley valais swiss alps result from the formation and growth of several lakes at the glacier margin and within the surrounding permafrost in order to prevent damage related to such hazards systematic investigations were carried out and practical measures taken the evolution of the polythermal glacier the creeping permafrost within the large adjacent rock glacier and the development of the various periglacial lakes were monitored and documented for the last 25 years by photogrammetric analysis of annually flown high resolution aerial photographs seismic refraction d c resistivity and gravimetry soundings were performed together with hydrological tracer experiments to determine the structure and stability of a moraine dam at a proglacial lake the results indicate a maximum moraine thickness of 100 m extremely high porosity and even ground caverns near the surface may have resulted from degradation of sub and periglacial permafrost following 19th 20th century retreat of the partially cold glacier tongue the safety and retention capacity of the proglacial lake were enhanced by deepening and reinforcing the outlet structure on top of the moraine complex the water level of an ice dammed lake was lowered and a thermokarst lake artficially drained

landsat based inventory of glaciers in western canada 1985 2005 abstract we report on a glacier inventory for the canadian cordillera south of 60 n across the two western provinces of british columbia and alberta containing 30 000 km2 of glacierized terrain our semi automated method extracted glacier extents from landsat thematic mapper tm scenes for 2005 and 2000 using a band ratio tm3 tm5 we compared these extents with glacier cover for the mid 1980s from high altitude aerial photography for british columbia and from landsat tm imagery for alberta a 25 m digital elevation model dem helped to identify debris covered ice and to split the glaciers into their respective drainage basins the estimated mapping errors are 3 4 and arise primarily from seasonal snow cover glaciers in british columbia and alberta respectively lost 10 8 3 8 and 25 4 4 1 of their area over the period 1985 2005 the region wide annual shrinkage rate of 0 55 a 1 is comparable to rates reported for other mountain ranges in the late twentieth century least glacierized mountain ranges with smaller glaciers lost the largest fraction of ice cover the highest relative ice loss in british columbia 24 0 4 6 occurred in the northern interior ranges while glaciers in the northern coast mountains declined least 7 7 3 4

inventorying slope movements in an alpine environment using dinsar differential sar interferometry dinsar is a technique that can be used to detect and characterize slope movements it is investigated here as a tool for establishing a detailed overview of complex slope movements at a regional scale in an alpine context this paper gives specific recommendations to use and to understand dinsar signals in mountainous areas located above the tree line excluding glaciated areas it proposes a systematic procedure based on accurate interpretations of interferometric signals from a large dinsar dataset to locate and estimate the displacement rate of moving zones the methodology was successfully applied in the western swiss alps where about 1500 moving objects were detected above the tree line using a large dataset of ers and jers interferograms dating from the 1990s the dinsar detected movements had a displacement rate ranging from a few centimeters to several meters per year and were attributed to various types of mass wasting phenomena rock glaciers landslides etc this kind of inventory derived from dinsar can be used as a preliminary tool for natural hazard management and process understanding in mountain areas as automatic data archiving and systematic acquisition of sar data are ensured worldwide for most sar sensors a similar methodology can basically be applied in many other parts of the globe also by using data from current sar sensors as long as a high resolution dem is available copyright 2014 john wiley sons ltd

a 10 300 year old permafrost core from the active rock glacier lazaun southern otztal alps south tyrol northern italy two cores were drilled on rock glacier lazaun in the southern otztal alps n italy the average ice content of core lazaun i is 43 vol and of core lazaun ii is 22 vol radiocarbon dating of plant macrofossil remains of core lazaun i yielded ages ranging from 8960 cal yr bp at a depth of ca 23 5 m to 2240 cal yr bp at a depth of 2 8 m indicating that the ice near the base is approximately 10 300 yr old the rock glacier was intact since that time and the ice persisted even during warm periods of the holocene an ice free debris layer between 16 8 and 14 7 m separates the rock glacier into two frozen bodies inclinometer measurements indicate that both frozen bodies are active and that deformation occurs within a shear horizon at a depth of 20 25 m at the base of the lower frozen body and to a minor extent at a depth of approximately 14 m at the base of the upper frozen body the ice free debris layer in the middle of the lazaun rock glacier indicates a more than five centennial long drought period which dates to about 4300 3740 cal yr bp

southern carpathian rock glaciers inventory distribution and environmental controlling factors abstract rock glaciers are valuable diagnostic landforms indicating permafrost creeping during their genesis and activity based on the analysis of high quality air orthophoto and field work a first polygon based inventory of rock glaciers from the southern carpathians has been elaborated in total 306 rock glaciers were included in the inventory comprising 79 debris and 227 talus rock glaciers most of these landforms were classified as relict 258 while only 48 covering 2 81 km 2 were considered intact the size of rock glaciers considered as a proxy for past environmental conditions and the relationships with the predictor variables lithology aspect contributing area geographic coordinates elevation and slope range were analysed using bivariate statistics analysis of variance anova and various post hoc tests the statistical analysis revealed that the rock glaciers occurring in the highest mountain ranges in areas composed of granites and granodiorites are considerably larger than the others because their duration of activity is greater strong dependences between rock glacier size and other topographic attributes contributing area aspect and slope range were also confirmed the rock glacier distribution in the southern carpathians is clearly controlled by topography lithology and debris availability the abundance of rock glaciers increases with altitude but their size decreases slightly in mountain units where granites and granodiorites predominate retezat and par ng mountains the density of rock glaciers and the mean specific area covered by these spectacular landforms are considerably higher than in other areas the higher continentality effects of the southern carpathians enabled the formation of rock glaciers at substantially lower elevations than in the alps the mean altitude of intact rock glaciers front which could be used as a morphological indicator of discontinuous permafrost is located at 2088 m

rock glaciers protalus ramparts and pronival ramparts in the south eastern alps abstract rock glaciers and protalus ramparts are characteristic landforms of the periglacial domain often used as markers for the occurrence of permafrost in mountain terrains as such relict rock glaciers can be used for paleoclimate reconstructions we present here the first previously unreported rock glacier inventory of the south eastern alps including the north eastern most region of italy and slovenia interpreted from high resolution orthophotos and a high resolution digital terrain model interpolated from airborne laser scanning lidar we mapped 53 rock glaciers covering a total area of 3 45 km 2 the majority of rock glaciers are classified as relict and distributed between 1708 and 1846 m a s l with slope ranging between 19 and 27 in addition to rock glaciers we observed 66 protalus pronival ramparts having median elevation of 1913 m a s l and covering 0 48 km 2 more than half of the inventoried protalus ramparts are located in the more maritime area of the alps with higher precipitation compared to the location of rock glaciers using paleoclimate reconstruction based on the 1981 2010 climatological record of the area we infer that the rock glaciers formed during one of the dry and cold periods of the late pleistocene and early holocene possible evolution of the active pronival forms observed in the most maritime area of this alpine sector is also discussed

a reconciled estimate of glacier contributions to sea level rise 2003 to 2009 glaciers distinct from the greenland and antarctic ice sheets are losing large amounts of water to the world s oceans however estimates of their contribution to sea level rise disagree we provide a consensus estimate by standardizing existing and creating new mass budget estimates from satellite gravimetry and altimetry and from local glaciological records in many regions local measurements are more negative than satellite based estimates all regions lost mass during 2003 2009 with the largest losses from arctic canada alaska coastal greenland the southern andes and high mountain asia but there was little loss from glaciers in antarctica over this period the global mass budget was 259 28 gigatons per year equivalent to the combined loss from both ice sheets and accounting for 29 13 of the observed sea level rise

the physical basis of glacier volume area scaling ice volumes are known for only a few of the roughly 160 000 glaciers worldwide but are important components of many climate and sea level studies which require water flux estimates a scaling analysis of the mass and momentum conservation equations shows that glacier volumes can be related by a power law to more easily observed glacier surface areas the relationship requires four closure choices for the scaling behavior of glacier widths slopes side drag and mass balance reasonable closures predict a volume area scaling exponent which is consistent with observations giving a physical and practical basis for estimating ice volumes glacier volume is insensitive to perturbations in the mass balance scaling but changes in average accumulation area ratios reflect significant changes in the scaling of both mass balance and ice volume

rock slope failure following late pleistocene deglaciation on tectonically stable mountainous terrain the ages of 31 postglacial rock slope failures rsfs in scotland and nw ireland derived from 89 cosmogenic isotope exposure ages are employed to analyse the temporal pattern of failure and its relationship to the timing of deglaciation rates of glacio isostatic crustal uplift and periods of rapid climate change rsf ages span almost the whole period since ice sheet retreat from 18 2 1 2 ka to 1 7 0 2 ka or from 17 1 1 0 ka to 1 5 0 1 ka depending on the production rate used in 10 be age calculation but catastrophic failure of rock slopes was w4 6 times more frequent prior to w11 7 ka than during the holocene 95 of dated rsfs at sites deglaciated during retreat of the last ice sheet occurred within w5400 years after deglaciation with peak rsf activity 1600e1700 years after deglaciation this time lag is inferred to represent 1 stress release initiated by deglacial unloading leading to 2 time dependent rock mass strength degradation through progressive failure plane development and ultimately 3 to either spontaneous kinematic release or failure triggered by some extrinsic mechanism by contrast 11 dated rsfs at sites reoccupied by glacier ice during the younger dryas stade yds of w12 9e11 7 ka exhibit no clear temporal pattern suggesting that glacial reoccupance during the yds was ineffective in preconditioning a renewed cycle of enhanced rsf activity comparison of timing of individual rsfs with that of deglaciation and rapid warming events at w14 7 ka and w11 7 ka suggests that glacial debuttressing enhanced joint waterpressuresduringdeglaciationandthawofpermafrosticeinrockjointscouldhavetriggeredfailurein only a small number of cases conversely the timing of maximum rsf activity following ice sheet deglaciation corresponds broadly with maximum rates of glacio isostatic crustal uplift suggesting that the two are linked by enhanced seismic activity a seismic failure trigger is consistent with full slope failure at all sites where failure planes are clearly defined our results indicate that numerous rsfs must have occurred in areas that were reoccupied by glacier ice during the yds but have not been identified because runout debris was removed by yds glaciers more generally they provide the first reliably dated body of evidence to support the view that retreat of the last ice sheets in tectonically stable mountainous terrain initiated a period of enhanced rock slope failure due to deglacial unloading and probably lateglacial seismic activity implying that most undated rsfs in such areas are probably of lateglacial or veryearly holocene age they also demonstrate however that a low frequency of rsf activity extended throughout the holocene

influence of glacier advance on the development of the multipart riffeltal rock glacier central austrian alps the multipart riffeltal rock glacier located in a tributary valley of the kaunertal tyrol austria is investigated to enlarge the knowledge about spatial and temporal development of rock glaciers in and at the margins of pro glacial areas and to get a better understanding of glacier rock glacier interactions the subject of interest consists of a complex system of two adjacent rock glacier tongues and various superposed lobes with differing ages origin and root zones and therefore diverse development to determine the reasons for their diverging development the internal structure and permafrost occurrence on and in the surrounding area of the rock glacier were studied by application of geomorphological mapping geophysical methods and measurement of the basal temperature of the winter snow cover bts permafrost modelling was performed on the basis of bts data and land surface parameters derived from a high resolution airborne laser scanning als digital elevation model dem additionally the als data were used to measure vertical and horizontal changes of the rock glacier surface between 2006 and 2012 glacier rock glacier interactions during and since the little ice age lia are evident for the development of the studied rock glacier a geomorphic map gives important information about the connection between glacial advance or retreat and permafrost or ground ice occurrence the combination of all information helps in the analysis of diverse kinematic action of neighbouring rock glacier tongues copyright 2014 john wiley sons ltd

rock glaciers and protalus landforms analogous forms and ice sources on earth and mars 1 the basic features and terminology of terrestrial rock glaciers are reviewed together with associated forms termed protalus lobes and protalus ramparts two basic models of rock glacier formation and flow invoke either the creep of ice derived from permafrost or glacial former glacial activity a third possible mechanism invokes landslide emplacement observations on terrestrial rock glaciers and similar forms suggest that the ice component can be produced via ground ice or from a glacier system finite element modeling of simple slope systems containing 1 a continuous ice layer buried by debris and 2 a mixture of ice and rigid blocks can both show creep but with very low rates especially at low temperatures possible martian examples of rock glacier and protalus lobe features are identified from candor chasma by wide angle mars orbiter camera moc imagery although the topography does not allow unambiguous interpretation some possible ways in which moc and mars orbiter laser altimeter mola and other mars orbiter data could help future interpretation of rock glaciers related protalus landforms and ice presence are discussed

glacier inventory and recent glacier variations in the andes of chile south america the first satellite derived inventory of glaciers and rock glaciers in chile created from landsat tm etm images spanning between 2000 and 2003 using a semi automated procedure is presented in a single standardized format large glacierized areas in the altiplano palena province and the periphery of the patagonian icefields are inventoried the chilean glacierized area is 23 708 1185 km 2 including 3200 km 2 of both debris covered glaciers and rock glaciers glacier distribution varies as a result of climatic gradients with latitude and elevation with 0 8 occurring in the desert andes 17 30 32 s 3 6 in the central andes 32 36 s 6 2 in the lakes district and palena province 36 46 s and 89 3 in patagonia and tierra del fuego 46 56 s glacier outlines across all glacierized regions and size classes updated to 2015 using landsat 8 images for 98 complexes indicate a decline in areal extent affecting mostly clean ice glaciers 92 3 4 6 km 2 whereas debris covered glaciers and rock glaciers in the desert and central andes appear nearly unchanged in their extent glacier attributes estimated from this new inventory provide valuable insights into spatial patterns of glacier shrinkage for assessing future glacier changes in response to climate change

rock glaciers and the geomorphological evolution of deglacierizing mountains abstract rock glaciers are an important geomorphic element of glaciated mountain landscapes but our understanding of their distribution and ages controls on their development and their importance in regional mountain hydrology and mountain geomorphic evolution is incomplete in part this incomplete knowledge arises through problems associated with identifying rock glaciers on a morphological basis alone amplified by the multiple ways in which rock glaciers can form in different glacial periglacial and paraglacial settings this study focuses on rock glaciers as a paraglacial mountain landscape element and considers the relationships between rock glaciers and glacial periglacial and paraglacial processes new geomorphic and sedimentary data on different rock glaciers from the khumbu region of nepal are presented these data show that even within a single region rock glaciers may have varied origins and thus likely ages and different climatic and environmental controls we argue that rock glaciers in deglacierizing mountains may have a long residence time in the landscape unlike many other glacially influenced mountain landforms and can undergo significant morphodynamic changes as glaciated landscapes transition into paraglacial landscapes

glacier meltwater flow paths and storage in a geomorphologically complex glacial foreland the case of the tapado glacier dry andes of chile 30 s summary the tapado catchment is located in the upper elqui river basin 4000 5550 m in northern chile it comprises the tapado glacial complex which is an assemblage of the tapado glacier and the glacial foreland debris covered glacier rock glacier and moraines although the hydrological functioning of this catchment is poorly known it is assumed to actively supply water to the lower semi arid areas of the elqui river basin to improve our knowledge of the interactions and water transfers between the cryospheric compartment glacier debris covered glacier and rock glacier and the hydrological compartment aquifers streams the results of monitoring of meteorological conditions as well as discharge conductivity and temperature of streams and springs located in the tapado catchment were analyzed the hydrological results are compared to results inferred from a ground penetrating radar gpr survey of the underground structure of the glacial foreland water production from the tapado glacier was shown to be highly correlated with daily and monthly weather conditions particularly solar radiation and temperature the resulting daily and monthly streamflow cycles were buffered by the glacial foreland where underground transfers took place through complex flow paths however the development of a thermokarst drainage network in a portion of the glacial foreland enabled rapid concentrated water transfers that reduced the buffer effect the glacial foreland was shown to act as a reservoir storing water during high melt periods and supplying water to downstream compartments during low melt periods gpr observations revealed the heterogeneity of the internal structure of the glacial foreland which is composed of a mixture of ice and rock debris mixture with variable spatial ice content including massive ice lenses this heterogeneity may explain the abovementioned hydrological behaviors finally calculation of a partial hydrological budget confirmed the importance of the tapado catchment in supplying water to lower areas of the elqui river basin water production from and transfer through cryospheric compartments and its subsequent interactions with hydrological compartments are key processes driving the summer water supply from the tapado catchment

the structure of a talus derived rock glacier deduced from its hydrology the paper presents the results of an experiment in the use of hydrological parameters to study the internal structure of a rock glacier the rock glacier selected for the study lies at the head of

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

sedimentological geomorphological and dynamic context of debris mantled glaciers mount everest sagarmatha region nepal abstract this paper presents the sediment landform and dynamic context of four avalanche fed valley glaciers khumbu imja lhotse and chukhung in the mount everest sagarmatha region of nepal all four glaciers have a mantle of debris dominated by sandy boulder gravel that suppresses melting to an increasing degree towards the snout leading to a progressive reduction in the overall slope of their longitudinal profile prominent lateral terminal moraine complexes also comprising sandy bouldergravel enclose the glaciers these terminal moraines originally grew by accretion of multiple sedimentary facies of basal glacial and supraglacial origin probably by folding and thrusting when the glaciers were more dynamic during the little ice age the four glaciers are in various stages of recession and demonstrate a range of scenarios from down wasting of the glacier tongue through morainedammed lake development to post moraine dam breaching khumbu glacier is at the earliest stage of supraglacial pond formation and shows no sign yet of developing a major lake although one is likely to develop behind its 250 m high composite terminal moraine imja glacier terminates in a substantial body of water behind a partially ice cored moraine dam as determined from geophysical surveys but morphologically appears unlikely to be an immediate threat chukhung glacier already has a breached moraine and a connected debris fan and therefore no longer poses a threat lhotse glacier has an inclined free draining tongue that precludes hazardous lake development from the data assembled a conceptual model applicable to other himalayan glaciers is proposed to explain the development of large lateral terminal moraine complexes and associated potentially hazardous moraine dams 2008 elsevier ltd all rights reserved

estimation of rock glacier surface deformation using sar interferometry data the detection and quantification of surface deformation of an active rock glacier using the differential synthetic aperture radar sar interferometry d insar technique is presented an average deformation rate of 6 mm 35 days in the radar line of ight was estimated for the summer of 1992 the maximum deformation rate 18 mm 35 days was identified at the upper part of the rock glacier whereas the deformation rate at the snout of the rock glacier was about 10 mm 35 days the spatial distribution of the surface deformation in the d insar displacement map is smooth and supports the idea that ice is the stress transferring medium in rock glaciers

engineering geomorphology of rock glaciers a partnership between geomorphology and engineering is facilitating human development in this harsh environment rock glaciers provide locations for urban water sources construction borrow sources drill sites shaft and tunnel portals ski tower supports and dam abutments rock glaciers as dynamic landforms necessitate proper identification in the field placing structures on in or adjacent to rock glaciers requires an appreciation and understanding of their temporal stability internal and surface characteristics provide important clues to the development and deformation of rock glaciers rock glaciers play a significant role in the alpine debris transport system active movement and mass wasting are perhaps the most obvious geologic hazards affecting engineered works the structure of the rock glacier is conducive to the production of a steady continuous supply of meltwater during summer months thus rock glaciers serve as alpine aquifers consideration of rock glaciers as potential aquifer sources requires caution because of the long term impact of climate change on the temporal nature of the landform from the rock glaciers that we have monitored for water quality characteristics it appears that they provide quality potable water this paper provides a foundation for appreciation and understanding of rock glaciers from an engineering geomorphologic point of view the approach taken in this paper provides practical important information to aid the engineer and engineering geologist in prudent evaluations of rock glaciers as potential sites for human development and uses the bottom line of our paper is rock glaciers must be avoided for essentially all structures

subsurface investigation of a rock glacier using ground penetrating radar implications for locating stored water on mars 1 the discovery of rock glacier like features on mars suggests the presence of flowing or once flowing ice rock mixtures these landforms which include lobate debris aprons concentric crater fill and lineated valley fill hold significant promise as reservoirs of stored water ice that could be used as fuel sources for human exploration of mars and provide a frozen record of the climatic history of the planet to understand the deformation and distribution of ice within these landforms fundamental descriptions of their internal structure and development are required to this end a ground penetrating radar investigation was initiated using rock glaciers in the san juan mountains of colorado as surrogates for similar martian landforms results obtained from one of these rock glaciers show that the interior of the landform is composed of a layered permafrost matrix of ice sediment and ice lenses that comprise thicker depositional units formed through high magnitude debris falls folds in the uppermost layers correspond to the surface expression of ridges and furrows suggesting that compressive stresses originating in the accumulation zone are transmitted downslope through the rock glacier rock glacier features on mars may also consist of layered permafrost which would suggest a history of development involving seasonal frost accumulation and or water influx from below in terms of water storage within martian analogs consideration must include the possibility that some water ice may be stored in relatively pure form within lenses and vein networks such as observed in the surrogate rock glacier of this study

low altitude permafrost research in an overcooled talus slope rock glacier system in the romanian carpathians detunata goală apuseni mountains abstract ground and air temperature monitoring geophysical soundings and dendrological investigations were applied to a basaltic talus slope rock glacier system from detunata site in the apuseni mountains western romanian carpathians to verify the presence of sporadic permafrost at 1020 1110 m asl well below the regional limit of mountain permafrost the near 0 c mean annual ground surface temperatures imposed by the large negative annual thermal anomalies of the ground up to 7 4 c together with the high resistivity values and the occurrence of trees with severe growth anomalies support the presence of permafrost at this location temperature measurements and ground air circulation experiments proved that the so called chimney effect is the main process favoring the ground overcooling and allowed for the construction of a model of ground air circulation in complex morphology deposits the texture and porosity of the debris were quantified along with the local morphology in order to evaluate their role upon the chimney circulation the debris porosity was found to be very high promoting intense ground overcooling during the cold season including the periods of high snow cover due to the development of snow funnels it efficiently reduces the heat transfer during summer thus contributing essentially to permafrost preservation in compound morphologies the depressed and low lying features are the cold zones subjected to winter overcooling and summer chill while the high positioned and convex up landforms become warm air evacuation features with positive thermal anomalies tree ring measurements showed that the growth of cold affected trees is higher during colder intervals years to decades probably as a consequence of the weakened katabatic air outflow during cooler summers the dendrological analysis of multi centennial spruces and their growth rates also provided palaeoclimatic inferences for the last 200 years

ice thickness measurements and volume estimates for glaciers in norway glacier volume and ice thickness distribution are important variables for water resource management in norway and the assessment of future glacier changes we present a detailed assessment of thickness distribution and total glacier volume for mainland norway based on data and modelling glacier outlines from a landsat derived inventory from 1999 to 2006 covering an area of 2692 81 km 2 were used as input we compiled a rich set of ice thickness observations collected over the past 30 years altogether interpolated ice thickness measurements were available for 870 km 2 32 of the current glacier area of norway with a total ice volume of 134 23 km 3 results indicate that mean ice thickness is similar for all larger ice caps and weakly correlates with their total area ice thickness data were used to calibrate a physically based distributed model for estimating the ice thickness of unmeasured glaciers the results were also used to calibrate volume area scaling relations the calibrated total volume estimates for all norwegian glaciers ranged from 257 to 300 km 3

interpretation of recent alpine landscape system evolution using geomorphic mapping and l band insar analyses abstract alpine landscapes are typically characterized by inherited features of past glaciations and for the more recent past by the interplay of a multitude of types of geomorphic processes including permafrost creep rockfalls debris flows and landslides these different processes usually exhibit large spatial and temporal variations in activity and velocity the understanding of these processes in a wide alpine area is often hindered by difficulties in their surveying in this study we attempt to disentangle recent changes in an alpine landscape system using geomorphic mapping and l band dinsar analyses alos palsar in the zermatt valley swiss alps geomorphic mapping points to a preferential distribution of rock glaciers on north facing slopes whereas talus slopes are concentrated on south facing slopes field based interpretation of ground deformation in rock glaciers and movements in talus slopes correlates well with the ratio of insar images showing potential ground deformation moraines formed during the little ice age rock glaciers and talus slopes on north facing slopes are more active than landforms on south facing slopes implying that the presence of permafrost facilitates the deformation of these geomorphic units such deformations of geomorphic units prevail also at the elevation of glacier termini for rock cliffs the ratio of images indicating retreat is affected by slope orientation and elevation linkages between sediment supply from rock cliffs and sediment transport in torrents are different among tributaries affected by relative locations between sediment supply areas and the channel network we conclude that the combined use of field surveys and l band dinsar analyses can substantially improve process understanding in steep high mountain terrain

current transition from glacial to periglacial processes in the dolomites south eastern alps abstract a close relationship between glacial and periglacial landforms is frequently observed in alpine environments where a transition from glacial to periglacial processes often took place after the end of the little ice age lia understanding the origin of these landforms is challenging and assessing the current spatial domain of glacial and periglacial processes may be a difficult task in high relief areas where thick and widespread debris cover often characterize rapidly decaying glaciers here we present a comprehensive study of a composite landform located in the dolomites south eastern alps combining geomorphological geophysical and topographic surveys with ground surface temperature measurements results indicate that a debris covered glacier persists in the upper part rather large compared to the lia extent but currently inactive and rapidly losing mass an active rock glacier exists in the lower part surrounded by discontinuous permafrost a frozen body about 10 m thick was detected in the rock glacier and geomorphological evidence suggests that this ice mass is completely detached from the debris covered glacier our findings suggest that the lower part of the composite landform is probably a remnant of the ancient glacier tongue and is currently evolving under periglacial conditions periglacial processes are therefore replacing glacial processes which dominated in this site during the lia

reconsidering the glacier to rock glacier transformation problem new insights from the central andes of chile abstract the glacier to rock glacier transformation problem is revisited from a previously unseen angle a striking case in the juncal massif located in the upper aconcagua valley chilean central andes is documented there the presenteseracae debris covered glacier has advanced several tens of metres and has developed a rock glacier morphology in its lower part over the last 60 years the conditions for a theoretically valid glacier to rock glacier transformation are discussed and tested permafrost probability in the area of the studied feature is highlighted by regional scale spatial modelling together with on site shallow ground temperature records two different methods are used to estimate the mean surface temperature during the summer of 2014 and the sub debris ice ablation rates are calculated as ranging between 0 05 and 0 19 cm d 1 i e 0 04 and 0 17 m over the summer these low ablation rates are consistent with the development of a coherent surface morphology over the last 60 years furthermore the rates of rock wall retreat required for covering the former glacier at presenteseracae lie within the common 0 1 2 mm y 1 range assuming an average debris thickness and a range of debris covering time intervals the integration of the geomorphological observations with the numerical results confirms that the studied debris covered glacier is evolving into a rock glacier

assessing the rock glacier kinematics on three different timescales a case study from the southern swiss alps surface temperature increases since the 1990s have often been associated with an increase in the speed of rock glaciers evidence of similar links on the centennial to millennial scale are however still lacking due to less focus to date on the medium and long term kinematics of these landforms in order to assess palaeo climatic variations in rock glacier kinematics we analysed the movements of the stabbio di largario rock glacier in the southern swiss alps using three different timescales the schmidt hammer exposure age dating shd was applied to study long term kinematics in order to extrapolate the minimal age of the formation of the rock glacier which may have started its development after the mid holocene climate optimum and to detect possible accelerations of the horizontal surface velocity during the medieval warm period georeferentiation and orthorectification of six historical photographs of the rock glacier taken between ad 1910 and today were analysed using monoplotting to detect the rock glacier displacement on the decennial scale from the end of the little ice age finally differential global positioning system dgps monitoring data available since ad 2009 were used to assess annual and seasonal creep rates of the rock glacier at present our results show a link between the periods of increase in mean air temperature on different timescales and variations in rock glacier kinematics and provide important new insights into rock glacier development and evolution on the long term scale

spatial distribution and morphometry of permafrost related landforms in the central pyrenees and associated paleoclimatic implications abstract present and past permafrost distribution in the pyrenees is still under discussion as in other mid latitude mountain regions rock glaciers and protalus lobes are the main indicators of permafrost conditions in this paper we examine the distribution of these landforms in aran and boi valleys formerly glaciated u shaped valleys ranging from 600 to 3000 m in the southern and northern sides of the central pyrenees respectively the spatial distribution of these landforms and their chronostratigraphic position within the valley allow a better understanding of the climatic and environmental conditions necessary for their development up to 151 permafrost related landforms were identified in the boi valley including 56 rock glaciers and 95 protalus lobes in the case of the northern aran valley 76 rock glaciers and 89 protalus lobes were cataloged corresponding to 165 landforms most of the landforms 93 for rock glaciers and 95 for protalus lobes are located inside the glacial cirques with a few distributed in the slopes of the formerly glaciated valleys the lowest elevation of rock glaciers is situated at 1744 m aran and 2007 m boi whereas the lowest protalus lobes are located at 1740 m and 2033 m respectively therefore this altitude may be indicative of the lowest level recording permafrost conditions during the period in which these landforms formed with paleotemperatures ca 7 8 c lower than present day between 60 and 70 of the protalus lobes and rock glaciers are located between 2300 and 2600 m in boi valley and 2100 and 2400 m in aran valley the aspect shows a prevailing orientation of nw n and ne for both cases of rock glaciers and protalus lobes being almost absent in the s se and sw aspects the average slope of both landforms lies between 11 and 27 with a maximum of 35 for rock glaciers and 29 for protalus lobes the amplitude length ratio reveals that rock glaciers placed at lower altitudes are more elongated the chronostratigraphic position of these landforms within the valley and with respect to the moraine complexes suggests the existence of three generations of permafrost related landforms which are associated to the massive deglaciation process between the maximum glacial advance of the last glaciation and the holocene

the randolph glacier inventory a globally complete inventory of glaciers the randolph glacier inventory rgi is a globally complete collection of digital outlines of glaciers excluding the ice sheets developed to meet the needs of the fifth assessment of the intergovernmental panel on climate change for estimates of past and future mass balance the rgi was created with limited resources in a short period priority was given to completeness of coverage but a limited uniform set of attributes is attached to each of the 198 000 glaciers in its latest version 3 2 satellite imagery from 1999 2010 provided most of the outlines their total extent is estimated as 726 800 34 000 km 2 the uncertainty about 5 is derived from careful single glacier and basin scale uncertainty estimates and comparisons with inventories that were not sources for the rgi the main contributors to uncertainty are probably misinterpretation of seasonal snow cover and debris cover these errors appear not to be normally distributed and quantifying them reliably is an unsolved problem combined with digital elevation models the rgi glacier outlines yield hypsometries that can be com bined with atmospheric data or model outputs for analysis of the impacts of climatic change on glaciers the rgi has already proved its value in the generation of significantly improved aggregate estimates of glacier mass changes and total volume and thus actual and potential contributions to sea level rise

rock glacier nomenclature a re assessment several contentious issues have arisen from rock glacier nomenclature for example whether the term rock glacier implies genesis from glacial ice or genesis from permafrost the situation is compounded since rock glacier classification may be based on several different parameters some of which are measured and quantified others inferred these include gross morphology dynamics processes of formation location internal characteristics thermal regime and age uncertainties in specifying the genesis in the light of the potential complexity means that definitions should be related to recognisable topographic forms which allow mapping of such features the distinction is made between rock glaciers sensu stricto which follows the original descriptions and typology of the early years of the 20th century and protalus lobes the forms can usually be differentiated in terms of length breadth ratios as well as by their relative locations some of the most common issues of contention within rock glacier research can be solved by this approach

polythermal glacier hydrology a review 1 the manner by which meltwater drains through a glacier is critical to ice dynamics runoff characteristics and water quality however much of the contemporary knowledge relating to glacier hydrology has been based upon and conditioned by understanding gleaned from temperate valley glaciers globally a significant proportion of glaciers and ice sheets exhibit nontemperate thermal regimes the recent growing concern over the future response of polar glaciers and ice sheets to forecasts of a warming climate and lengthening summer melt season necessitates recognition of the hydrological processes in these nontemperate ice masses it is therefore timely to present an accessible review of the scientific progress in glacial hydrology where nontemperate conditions are dominant this review provides an appraisal of the glaciological literature from nontemperate glaciers examining supraglacial englacial and subglacial environments in sequence and their role in hydrological processes within glacierized catchments in particular the variability and complexity in glacier thermal regimes are discussed illustrating how a unified model of drainage architecture is likely to remain elusive due to structural controls on the presence of water cold ice near glacier surfaces may reduce meltwater flux into the glacier interior but observations suggest that the transient thermal layer of near surface ice holds a hydrological role as a depth limited aquifer englacial flowpaths may arise from the deep incision of supraglacial streams or the propagation of hydrofractures forms which are readily able to handle varied meltwater discharge or act as locations for water storage and result in spatially discrete delivery of water to the subglacial environment the influence of such drainage routes on seasonal meltwater release is explored with reference to summer season upwellings and winter icing formation moreover clear analogies emerge between nontemperate valley glacier and ice sheet hydrology the discussion of which indicates how persistent reassessment of our conceptualization of glacier drainage systems is required there is a clear emphasis that continued integrated endeavors focused on process glaciology at nontemperate glaciers are a scientific imperative to augmenting the existing body of research centered on ice mass hydrology

the problem of hidden ice in glacier mapping lee can become hidden i e buried by the superimposition of rock debris on a glacier or where rock debris may incorporate interstitial ice because it is obscured problems result from a lack of understanding of the extent and continued activity of such ice landforms may be associated with this phenomenon and can be used as indirect evidence of its existence a rock glacier can contain glacially derived buried ice as well as interstitial ice we show with examples how such rock glaciers can be identified and provide information on the extent and possible volume of hidden ice in marginally glacierized and permafrost areas in most cases recognition of topography is sufficient although time separated aerial photographs may be necessary to locate the extent of ice these are generally preferable to and more cost effective than most detailed on site determinations of ice extent it is possible to incorporate and extend knowledge of hidden ice in glacier mapping and inventory projects

the second chinese glacier inventory data methods and results the second chinese glacier inventory was compiled based on 218 landsat tm etm scenes acquired mainly during 2006 10 the widely used band ratio segmentation method was applied as the first step in delineating glacier outlines and then intensive manual improvements were performed the shuttle radar topography mission digital elevation model was used to derive altitudinal attributes of glaciers the boundaries of some glaciers measured by real time kinematic differential gps or digitized from high resolution images were used as references to validate the accuracy of the methods used to delineate glaciers which resulted in positioning errors of 10 m for manually improved clean ice outlines and 30 m for manually digitized outlines of debris covered parts the glacier area error of the compiled inventory evaluated using these two positioning accuracies was 3 2 the compiled parts of the new inventory have a total area of 43 087 km 2 in which 1723 glaciers were covered by debris with a total debris covered area of 1494 km 2 the area of uncompiled glaciers from the digitized first chinese glacier inventory is similar to 8753 km 2 mainly distributed in the southeastern tibetan plateau where no images of acceptable quality for glacier outline delineation can be found during 2006 10

water flow through temperate glaciers understanding water movement through a glacier is fundamental to several critical issues in glaci ology including glacier dynamics glacier induced floods and the prediction of runoff from glacierized drainage basins to this end we have synthesized a conceptual model of water movement through a temper ate glacier from the surface to the outlet stream pro cesses that regulate the rate and distribution of water input at the glacier surface and that regulate water movement from the surface to the bed play important but commonly neglected roles in glacier hydrology where a glacier is covered by a layer of porous perme able firn the accumulation zone the flux of water to the glacier interior varies slowly because the firn tempo rarily stores water and thereby smooths out variations in the supply rate in the firn free ablation zone in con trast the flux of water into the glacier depends directly on the rate of surface melt or rainfall and therefore varies greatly in time water moves from the surface to the bed through an upward branching arborescent net work consisting of both steeply inclined conduits formed by the enlargement of intergranular veins and gently inclined conduits spawned by water flow along the bottoms of near surface fractures crevasses engla cial drainage conduits deliver water to the glacier bed at a limited number of points probably a long distance downglacier of where water enters the glacier englacial conduits supplied from the accumulation zone are quasi steady state features that convey the slowly varying water flux delivered via the firn their size adjusts so that they are usually full of water and flow is pressurized in contrast water flow in englacial conduits supplied from the ablation area is pressurized only near times of peak daily flow or during rainstorms flow is otherwise in an open channel configuration the subglacial drainage system typically consists of several elements that are distinct both morphologically and hydrologically an up glacier branching arborescent network of channels in cised into the basal ice conveys water rapidly much of the water flux to the bed probably enters directly into the arborescent channel network which covers only a small fraction of the glacier bed more extensive spatially is a nonarborescent network which commonly includes cav ities gaps between the glacier sole and bed channels incised into the bed and a layer of permeable sediment the nonarborescent network conveys water slowly and is usually poorly connected to the arborescent system the arborescent channel network largely collapses during winter but reforms in the spring as the first flush of meltwater to the bed destabilizes the cavities within the nonarborescent network the volume of water stored by a glacier varies diurnally and seasonally small temper ate alpine glaciers seem to attain a maximum seasonal water storage of 200 mm of water averaged over the area of the glacier bed with daily fluctuations of as much as 20 30 mm the likely storage capacity of subglacial cavities is insufficient to account for estimated stored water volumes so most water storage may actually occur englacially stored water may also be released abruptly and catastrophically in the form of outburst floods

an inventory of cryospheric landforms in the arid diagonal of south america high central andes atacama region chile abstract an integral glacial and periglacial inventory of the cryosphere in the atacama region in chile was carried out to estimate the amount of frozen water reserves in this arid to hyper arid region the inventory was carried out with medium to high spatial resolution satellite images and resulted in a total of 168 908 ha of landforms with significant ice content in one of the most fragile andean ecosystems the semi arid hyper arid zones this study shows an integral mapping of the cryosphere including glaciers and ice bearing periglacial landforms the different ice landforms in the atacama region shows a progressive change in the landforms containing ice responding to the northwards increase of aridity upon entry to the south american hyper arid axis the main change observed is that uncovered glaciers are not present north of 26 5 s being replaced by creeping permafrost landforms uncovered glaciers may produce more water annually compared to other ice bearing landforms but they only represent 2 7 of the cryospheric area however cryoforms containing a mixture of ice sediment and rock fragments could be more important as water reserves because of their large extensions that cover c 97 of the total area of ice bearing landforms mapped it also shows that the water supply potential of ice bearing periglacial landforms could be much higher than that of the glaciers in arid zones the comparison with the previous inventory of 1987 suggests a reduction of 34 of uncovered glaciers which is consistent with the aridization process observed in almost all of northern chile these findings reinforce the fact that glaciers and other types of permanent ice bearing landforms need to be inventoried together if the objective is to provide the society with a realistic view of the distribution of the cryospheric hydrological resources in desert regions

fast deformation of perennially frozen debris in a warm rock glacier in the swiss alps an effect of liquid water 1 surface movement internal deformation and temperature were monitored over 5 years on buz north rock glacier a small rock glacier located at the lower limit of the permafrost belt in the swiss alps the permafrost in the rock glacier mainly consists of pebbles and cobbles filled with interstitial ice two inclinometers installed at 4 and 5 m depths showed fast deformation with large seasonal and interannual variations while the permafrost temperatures remained almost at the melting point the movement of the inclinometers coincided with changes in the surface velocities the deformation rapidly accelerated during snowmelt periods whereas it gradually decelerated below a dry snow cover in winter the frozen debris was more deformable than typical glacier ice at the melting point these phenomena suggest that the frozen debris is permeable to snowmelt water the fast deformation should result from significant annual relocation of debris particles which probably creates a network of air voids in the frozen debris that eventually allows water infiltration the meltwater infiltration accelerates the deformation by reducing effective stress resulting in the reduced strength of the frozen debris the refreezing of the pore water which depends on the cooling intensity in winter decelerates the deformation the combination of these processes controls the temporal variations in the deformation

thermal and hydrologic attributes of rock glaciers and periglacial talus landforms sierra nevada california usa abstract to explore thermal regimes and hydrologic capacity of rock glaciers and related periglacial talus landforms mini thermochrons were deployed in and around potentially ice embedded features of the sierra nevada results from pilot studies at 13 rock glaciers and 7 taluses indicate that outlet springs from these landforms generally do not desiccate but persist year round as ice frozen in winter and flowing water in the warm season temperatures of water liquid and ice in rock glacier outlet springs had an annual mean of 0 2 c and mean of 0 6 c during the warm season with very low diurnal fluctuation these and other attributes suggest the existence of internal ice and or permafrost supplying the springs air temperatures of rock glacier matrices 1 m below the surface versus surface air corroborate the periglacial nature of internal environments annual air temperatures of matrices were below freezing mean 0 8 c compared to surface air especially during the warm season matrix air temperatures were significantly colder and fluctuated less talus landforms followed a similar pattern although water and matrix air temperatures were warmer and contrasts with surface air were not as strong as for rock glaciers for rock glaciers and talus slopes matrix air temperatures showed resistance buffering to changes in external air temperatures unique geomorphic conditions of rock glaciers and periglacial taluses in the sierra nevada appear to maintain cool buffered thermal regimes at least partly decoupled from external air springs support persistent wetlands and lakes at their snouts retaining water in otherwise semi arid high cirques and contribute as hydrologic reserves and critical habitat for alpine biota daily and seasonal lags and buffering effects suggest that ice within these landforms might resist surface warming on the longer term which could make these landforms increasingly important as regional climates change

dynamics of an active rock glacier otztal alps austria the rock glacier innere olgrube located in a small side valley of the kauner valley otztal alps austria consists of two separate tongue shaped rock glaciers lying next to each other investigations indicate that both rock glaciers contain a core of massive ice during winter the temperature at the base of the snow cover bts is significantly lower at the active rock glacier than on permafrost free ground adjacent to the rock glacier discharge is characterized by strong seasonal and diurnal variations and is strongly controlled by the local weather conditions water temperature of the rock glacier springs remains constantly low mostly below 1 c during the whole melt season the morphology of the rock glaciers and the presence of meltwater lakes in their rooting zones as well as the high surface flow velocities of 1 m yr point to a glacial origin the northern rock glacier which is bounded by lateral moraines evolved from the debris covered tongue of a small glacier of the little ice age with its last highstand around a d 1850 due to the global warming in the following decades the upper parts of the steep and debris free ice glacier melted whereas the debris covered glacier tongue transformed into an active rock glacier due to this evolution and due to the downslope movement the northern rock glacier although still active at present is cut off from its ice and debris supply the southern rock glacier has developed approximately during the same period from a debris covered cirque glacier at the foot of the wannetspitze massif

benchmarking classifiers to optimally integrate terrain analysis and multispectral remote sensing in automatic rock glacier detection abstract the performance improvements that can be achieved by classifier selection and by integrating terrain attributes into land cover classification are investigated in the context of rock glacier detection while exposed glacier ice can easily be mapped from multispectral remote sensing data the detection of rock glaciers and debris covered glaciers is a challenge for multispectral remote sensing motivated by the successful use of digital terrain analysis in rock glacier distribution models the predictive performance of a combination of terrain attributes derived from srtm shuttle radar topography mission digital elevation models and landsat etm data for detecting rock glaciers in the san juan mountains colorado usa is assessed eleven statistical and machine learning techniques are compared in a benchmarking exercise including logistic regression generalized additive models gam linear discriminant techniques the support vector machine and bootstrap aggregated tree based classifiers such as random forests penalized linear discriminant analysis plda yields mapping results that are significantly better than all other classifiers achieving a median false positive rate mfpr estimated by cross validation of 8 2 at a sensitivity of 70 i e when 70 of all true rock glacier points are detected the gam and standard linear discriminant analysis were second best mfpr 8 8 followed by polyclass for comparison the predictive performance of the best three techniques is also evaluated using 1 only terrain attributes as predictors mfpr 13 1 14 5 for best three techniques and 2 only landsat etm data mfpr 19 4 22 7 yielding significantly higher mfpr estimates at a 70 sensitivity the mfpr of the worst three classifiers was by about one quarter higher compared to the best three classifiers and the combination of terrain attributes and multispectral data reduced the mfpr by more than one half compared to remote sensing only these results highlight the importance of combining remote sensing and terrain data for mapping rock glaciers and other debris covered ice and choosing the optimal classifier based on unbiased error estimators the proposed benchmarking methodology is more generally suitable for comparing the utility of remote sensing algorithms and sensors

statistical estimation and generalized additive modeling of rock glacier distribution in the san juan mountains colorado united states 1 our goal is to quantify rock glacier abundance and analyze the topographic controls of rock glacier distribution patterns for this purpose we use statistical estimation techniques and generalized additive models relating rock glacier occurrences to terrain attributes significant applied results include the ability to determine water equivalence and denudation rates the statistical estimation of regional rock glacier abundance based on local interpretation of air photos is an efficient alternative to costly rock glacier inventories these presence absence data n 2933 also allow us to analyze the partly nonlinear topographic controls on rock glacier distribution with generalized additive models we apply these techniques in the san juan mountains 2874 km2 above 3400 m colorado where we obtained a total rock glacier surface area of 70 km2 corresponding to a water equivalence in the order of 0 50 0 76 km3 estimated rock glacier debris volumes imply postglacial denudation rates on the order of 0 5 1 1 mm yr 1 within the talus sheds of rock glaciers the distribution model shows the nonlinear factors of local slope slope of the contributing area local curvature and size of the contributing area controlling the probability of rock glacier occurrence the model yields an area under the receiver operating characteristics curve of 0 91 which indicates an excellent fit on the basis of the present results the integration of terrain attributes with remote sensing data will be the next step toward automatic mapping of rock glaciers in vast mountain areas

the internal structure of rock glaciers and recently deglaciated slopes as revealed by geoelectrical tomography insights on permafrost and recent glacial evolution in the central and western alps italy france abstract ground ice of permafrost origin and sedimentary ice of glacial origin can coexist in locations where rock glaciers and glaciers interacted as well as in glacigenic sediments abandoned by a retreating glacier and subsequently exposed again to atmospheric cooling some of these geomorphological settings in the central foscagno rock glacier and western alps marinet and schiantala rock glaciers schiantala debris covered glacier maledia glacier were explored by means of geoelectrical tomographies the aim was that of inferring the presence of ice and cryologically interpreting electrical stratigraphies in order to test whether or not the internal structure of these landforms can be used for the reconstruction of recent permafrost and glacier evolution geomorphological data assisted these reconstructions and available borehole stratigraphies were used to calibrate the resistivities along with the ice debris mixture massive ice has also been found as lenses both at the apex and the front of the studied rock glaciers these lenses of sedimentary origin are thought to be transferred from a glacier snout to sectors of rock glacier and eventually embedded into the permafrost creep the scarcity of frozen debris in the mid upper part of the rock glaciers as revealed by low resistivity values can be due to the disruptive effect of the over riding glacier over the permafrost the near surface sedimentary ice masses detected along the slopes of the studied glacial cirques are interpreted as or debris covered terminations of the glaciers still visible upward or as fragments of it detached by the main bodies these ice masses are locally associated to medium high resistive sediments consistent with permafrost occurrence this indicates that the non glacial environment established during the deglaciation allowed the onset of frozen sediments formation overall the results indicate that internal structure of rock glaciers and recent deglaciated slopes can store the different climate related episodes occurred in a specific area such as those linked to the shifting between glacial to criotic condition and vice versa

a new 3 d thin skinned rock glacier model based on helicopter gpr results from the swiss alps mountainous locations and steep rugged surfaces covered by boulders and other loose debris are the main reasons why rock glaciers are among the most challenging geological features to investigate using ground based geophysical methods consequently geophysical surveys of rock glaciers have only ever involved recording data along sparse lines to address this issue we acquired quasi 3 d ground penetrating radar gpr data across a rock glacier in the swiss alps using a helicopter mounted system our interpretation of the derived gpr images constrained by borehole information results in a novel thin skinned rock glacier model that explains a concentration of deformation across a principal shear zone decollement and faults across which rock glacier lobes are juxtaposed the new model may be applicable to many rock glaciers worldwide we suggest that the helicopter gpr method may be useful for 3 d surveying numerous other difficult to access mountainous terrains