Search

Paleoclimatic constraints from mountain ranges separating major climate systems are important in understanding past climatic changes. Using the present-day glacial geomorphology combined with the GlaRe model, the last glacial maximum (LGM) of seven representative valley glaciers of the Pir Panjal Range (PPR), Kashmir Himalaya was reconstructed. The Range lies at the interface of the tropical and temperate climates in the NW Himalayas. The glacier reconstructions showed that the glaciers in the Range advanced ~10 km down the present-day cirque margins and attained a thickness of more than 200 m during the LGM. Using six different methods, the equilibrium line altitude (ELA) changes in the selected valleys of the PPR were estimated for which the LGM was reconstructed. ELA depressions calculated for the LGM vary from 374 m to 416 m with a mean of 395 m. The weighted average ELA of the Range lies at an altitude of 3922 m a.s.l showing a general increasing trend from SE to NW of the Range. The published chronology of the loess deposits, a proxy for glacial aridity, shows the evidence of significant glacial advances starting around 350 kya in the valley, which is consistent with the evidence of both the pre- and post-LGM advances observed in this study. The presence of extensive glacier features all across the PPR and the presence of a few small heavily debris-covered glaciers in the Range points towards the rapid deglaciation in the area.

The Skuta Glacier in the Kamnik–Savinja Alps (in northern Slovenia) is one of the two remaining glaciers in Slovenia. It is located in a cirque oriented toward the northwest, which shields it from sunlight for most of the year. The glacier lies at an average elevation of 2070m. In recent years, its average area has measured around 1.5 hectares. Monitoring of the glacier has been performed since 1946. In 1962, regular photographing of the glacier with various cameras started from various non-fixed standpoints. Using the single image interactive orientation acquisition method, in which a single photograph is compared with the projection of a modern digital terrain model, seventeen photographs covering the period from 1970 to 2015 were used to acquire the 3D-perimeters of the glacier. The data shows that the elevation of glacier’s upper edge decreased by approximately 40m in the last half-century. Changes in the glacier’s area and average upper edge elevation were compared with average annual temperature and maximum seasonal snow cover depth.

In the European Alps, almost half the glacier volume has disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques, surface lowering exposes rock to atmospheric conditions probably for the very first time in several millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high resolution is missing. Based on terrestrial lidar, a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn) is established. Over 6 years (2011–2017), 78 rockwall scans were acquired to generate data of high spatial and temporal resolution. Overall, 632 rockfalls were registered, ranging from 0.003 to 879.4 m3, mainly originating from pre-existing structural rock weaknesses. A total of 60 % of the rockfall volume detached from less than 10 vertical metres above the glacier surface, indicating enhanced rockfall activity over tens of years following deglaciation. Debuttressing seems to play a minor effect only. Rather, preconditioning is assumed to start inside the randkluft (void between cirque wall and glacier) where measured sustained freezing and ample supply of liquid water likely cause enhanced physical weathering and high quarrying stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into the formerly perennially frozen bedrock. These factors likely cause the observed paraglacial rockfall increase close to the glacier surface. This paper, the first of two companion pieces, presents the most extensive dataset of high-alpine rockfall to date and the first systematic documentation of a cirque-wide erosion response of glaciated rockwalls to recent climate warming.

Cirque erosion contributes significantly to mountain denudation and is a key element of glaciated mountain topography. Despite long-standing efforts, rates of rockwall retreat and the proportional contributions of low-, mid- and high-magnitude rockfalls have remained poorly constrained. Here, a unique, terrestrial-lidar-derived rockfall inventory (2011–2017) of two glaciated cirques in the Hohe Tauern range, Central Alps, Austria, is analysed. The mean cirque wall retreat rate of 1.9 mm a−1 ranks in the top range of reported values and is mainly driven by enhanced rockfall from the lowermost, freshly deglaciated rockwall sections. Retreat rates are significantly elevated over decades subsequent to glacier downwasting. Elongated cirque morphology and recorded cirque wall retreat rates indicate headward erosion is clearly outpacing lateral erosion, most likely due to the cataclinal backwalls, which are prone to large dip-slope failures. The rockfall magnitude–frequency distribution – the first such distribution derived for deglaciating cirques – follows a distinct negative power law over 4 orders of magnitude. Magnitude–frequency distributions in glacier-proximal and glacier-distal rockwall sections differ significantly due to an increased occurrence of large rockfalls in recently deglaciated areas. In this paper, the second of two companion pieces, we show how recent climate warming shapes glacial landforms, controls spatiotemporal rockfall variation in glacial environments and indicates a transient signal with decadal-scale exhaustion of rockfall activity immediately following deglaciation crucial for future hazard assessments.

Many formerly glaciated valleys in the western United States preserve detailed glacial features that span the penultimate glaciation through the last deglaciation; however, numerical age control is limited in many of these systems. We report 35 new cosmogenic 10Be surface exposure ages of moraine boulders in the Sawatch Range, Colorado. Eight ages suggest Bull Lake moraines in Lake Creek (range: 132–120 ka, n = 4) and Clear Creek (range: 187–133 ka, n = 4) valleys may correlate with Marine Isotope Stage 6. In Lake Creek valley, 22 10Be ages from Pinedale end moraines average 20.6 ± 0.6 ka, and 5 10Be ages from a recessional moraine average 15.6 ± 0.7 ka, indicating that glaciers occupied two extended positions at ~21–20 and ~16 ka. The glacial extent dated to ~16 ka was nearly as great as that of the earlier glacial phase, suggesting that climate conditions in the Colorado Rocky Mountains at this time were similar to those of the last glacial maximum. Combining these moraine ages with seven previously published 10Be ages from cirque and valley-bottom bedrock reveals that the Lake Creek paleoglacier lost 82% of its full glacial length in ~1.5 ka and was completely deglaciated by ~14 ka.

There are no glaciers today in the High Atlas, Morocco. However, there is evidence that niche glaciers and late-lying snowpatches in the High Atlas were present as recently as the last century and there are at least four sites where snowpatches appear to survive some summer seasons today. Many other sites also support non-perennial late-lying snow below steep shaded north and northeast-facing cliffs at altitudes > 3100 m. Coarse sediment ridges interpreted as moraines or pronival ramparts enclose most of these snowpatches. These landforms most likely record the positions of former niche glaciers and late-lying snowpatches in the Little Ice Age. The niche glaciers and late-lying snowpatches survived below the regional equilibrium line altitude because of strong local topoclimatic controls. In addition to strong shading, many of the current late-lying snowpatches are fed by long deep gullies which funnel avalanching snow from the cirque backwalls. The disappearance of many perennial snowpatches in the last few decades coincides with a strong trend towards warmer summer air temperatures since the 1970s (> 2 °C). However, inter-annual changes in snowpack mass balance are affected by very large variations (> 400% variability) in winter precipitation. A new research programme is underway investigating the history of late-lying snow and cirque glaciers in the High Atlas. A particular focus of this research is to utilise geomorphological and geochronological evidence to understand fluctuations in snow and ice through the Holocene and link this to continuous records of environmental change in the High Atlas region.

The morphology of glacier is a key factor impacting the glacier mass redistributions. High-resolution digital elevation models (DEMs) provide a reliable method to explore the vertical characteristics of glacier surface elevation changes in different types. Using topographic maps from 1969 and Shuttle Radar Topography Mission (SRTM) data acquired in 2000, we calculated the surface elevation changes for 18 glaciers to generate vertical profiles of elevation difference (VPED) in the Dongkemadi region, central Tibetan Plateau. The results showed that the VPEDs vary highly among different glacier types. For valley glaciers, surface thinning at middle elevations is less than that at higher and lower elevations; for cirque glaciers, however, the maximum surface decline occurred in the middle section; whereas hanging glaciers experienced progressively less surface lowering with increasing elevation. Glacier geometry directly affects ice dynamics, which in turn dictates the VPEDs of specific glaciers. This regulation of glacier evolution can be applied to project how valley glaciers might eventually assume the VPEDs of cirque and hanging glaciers due to ongoing warming.

Between the Klondike Plateau and Yukon–Tanana highlands of Yukon and Alaska, respectively, current maps explain glaciated alpine locales and periglacial areas in terms of localized Pliocene–Pleistocene montane ice caps, alpine glaciers, and periglacial changes. However, this region’s plateau topography is populated with long undulating ridges having wide flattened tops; it contrasts with relief of other regions of northwestern North America also affected by ice caps, cryoplanation, and erosion over similar duration during the same epochs. This region has received minimal research and appears to present a new opportunity for resolving outstanding glaciological and stratigraphy issues. The glaciological history is reviewed, placing particular emphasis upon the low-elevation ridges within the “unglaciated” region, suggesting that those ridges are relict arête/cirque remnants. Sites of subalpine glacial grooving and mountaintop planing are also identified, and a conglomeratic red bed containing erratic clasts is described. All indications point to the “unglaciated” region having been glaciated before late Pliocene. Two working hypotheses are proposed: (1) The landscape once supported a range of young mountains that became glaciated then overridden and pared to a plateau by an ice sheet. (2) Following deglaciation, an extended period of paraglacial activity removed most of the former drift and excised new valleys to give the region an unglaciated appearance, which thereafter became modified into its present state by local montane/alpine glaciations, interglacial cryoplanation, periglacial gelifraction, and erosion. In addition to Pliocene–Pleistocene glaciations, a northeastward advancing Miocene ice sheet seems plausible and, on the basis of paleographic considerations and lithology, a Cretaceous glaciation evidently is also not out of the question.

The Northern part of the Sredinny (Middle) Range is the largest glaciation area in Kamchatka in terms of the numbers and areas of glaciers. As of 2016–2017, there were 465 glaciers in this area with a total area of about 255±17 km2. Amongst the morphological types, the cirque (corrie), slope, and corrie-valley glaciers predominate (64%), but more than half of the total area (54%) is covered by the corrie-valley and transaction glaciers. The average area of glaciers over this region is 0.55 km2, while for the transection ones it is 8.3 km2. The main part (77.4%) of the glaciers in the region is located in the altitude range of 1200–1800 m. The firn line on both slopes of the Central Range lies within the altitude range of 880–1910 m. Analysis of changes in the size of the recent glaciation in comparison with the data of the mid-twentieth century indicates that the trend towards its reduction, established in the second half of the twentieth century, remains at the present time. The loss of the area of glaciers in the region registered in the USSR Glacier Inventory (1950), by 2016–2017 amounts to almost 125 km2 (35.6%). Note, that losses for the first 15 years of the twenty-first century turn out to be approximately equal to the total sum of losses for second half of the twentieth century. It means that at the beginning of the twenty-first century the rate of reduction of glaciers is 4.3 times greater, i.e. about 1.45% of the area per year. The glaciers of the South-Eastern (62.9%) and Southern (43.6%) exposures reduced the most (significantly more than others). Loss of the total area was the greatest in small glaciers with sizes smaller 0.1 km2 (> 70%) and the smallest in large glaciers exceeding 5 km2 (< 11%). The process of disintegration of large glaciers into smaller ones did also accelerate, that increased total number of glaciers. The increase in the rate of glaciers area reduction in the region at the beginning of the twenty-first century was mainly caused by the rise in summer air temperatures, that also intensified in these years. Similar values of the relative reduction of glacier areas are observed in the North Chui Range (Altay), in the Bernese and Pennine Alps, in the Polar Ural, in the Nordenskjold Land (Svalbard), etc.

We analyzed multi-time satellite images of the Central Caucasus glacial zone and interpreted more than thirty rock avalanche events in the 21st century with a total damage area of more than 25 km 2 (including the collapse zone of the Kolka Glacier disaster). The highest rock and rock-ice avalanche activity is detected in the section of The Greater Caucasus range (northern and southern slopes) with a length of about 20 km between the Bashkara and Kulaktau peaks (16 rock avalanches) and in the section of the Kazbek-Dzhimaray Massif (series of rock avalanches to the surface of Kolka, Suatisi and Devdoraki glaciers). The feature of the rock and ice-rock avalanches is the large runout distance. For 12 events (about 40%) the distance was more than 2000 m. One ice-rock avalanche from the Mount Kazbek (excluding the Kolka Glacier disaster in 2002) reached the runout distance more than 10 km. In some areas, the rock avalanches occurred several times. In particular, a large number of avalanches were in the cirque of the Kolka Glacier; the last of them at the end of 2019. Thrice шт each case, rock avalanches originated from Mount Bashkara, in the cirques of the Murkvam Glacier, the East Shtulu Glacier, and the Devdoraki Glacier. Ice and rock avalanches were the initial stage of the complex process of the Kolka Glacier disaster and following catastrophic glacial debris flow in the Genaldon/Gizeldon River valley in 2002. Also, they were causes of glacier surges, formation of dammed lakes, and debris flows. As a result of the collapse of the hanging glacier and bedrock, the former right tributary of the Kolka Glacier surged to 200 m in 2006. Ice-rock avalanche from Mount Kazbek in 2014 load up the former right tributary of the Devdoraki Glacier and caused its advancing in 2015–2019, at a distance of more than 400 m. The avalanches caused catastrophic debris flows in the Amilishka/Kabakhi River valley in 2014, the Mestiachala River valley in 2019. Rock avalanches can cause outbursts of lakes and debris flows. Two dammed lakes formed as a result of the rock avalanche from the cirque above the Seri Glacier in the Tviberi River valley of the in May 2016. The lakes (total area was more than 0.05 km 2 ) have outburst at the end of August 2017 after heavy rains. Rock avalanches of the 20th century led to an abrupt deceleration in the retreat of the Yusengi, Bartuytsete, East Shtulu and Mosota glaciers. The formation of rock avalanches in the 21st century took place at high altitudes (an average of about 3900 m). Possibly, the reason was associated with an increase of the «0» isotherm and of the high border of the zone of intense frost weathering due to climate warming. Some rock avalanches in the section of the Kazbek-Dzhimarai Massif have been caused by endogenous factors (seismicity and volcanism).

In the Northern Romanian Carpathians (NRC) small Pleistocene cirque glaciers have formed in several isolated mountain massifs exceeding 1800 m asl. This paper brings forward new geomorphological evidence of marginal glaciation in the Calimani, Suhard, and Gurghiu Mountains which are the southernmost glaciated areas of the NRC. We reconstructed the extent and ice-surface geometry for 12 palaeo-glaciers in the study area during the Maximal Ice Extent (MIE) which is attributed to LGM. The equilibrium line altitudes (ELAs) calculated using the area-altitude-balance-ratio (AABR) 1.6. were between 1740 m and 1870 m which is the highest value in the Eastern Carpathians and one of the highest in the entire Carpathians. The specific features of the Calimani and Gurghiu Mountains are the extensive, gentle outer slopes of volcanic calderas that play an important role as additional areas for snowblow accumulation. Inclusion of the potential snow contribution area (snowblow and avalanche accumulation) in the ELA calculation resulted in an additional upward ELA shift up to 66 m (up to 40% of the glacier elevation range). Our data indicate that small cirque glaciation in the NRC could develop when mountain ranges are at least 100 m above the extrapolated regional ELA. The general ELA pattern in the NRC shows a positive trend (∼3 m/km) which could reflect both the general rise in temperature and the starvation of precipitation toward the southeast. However, the observed eastward ELA rise on W-E transects in the Eastern Carpathians shows a pure precipitation effect and indicates the influence of zonal atmospheric circulation in the far interior of Europe during the LGM.

Detailed geomorphological mapping over several decades has led to the conclusion that the Quaternary glaciation left a strong imprint in the geomorphological landscape of all mountain massifs higher than 2000 m. They are present two main types of geomorphologic landscapes, the Borascu glacial landscape, with glacial cirques developed at the edge of planation surfaces, and Fagaraș landscape, a typical alpine-style glacial landscape. In Last Glacial Maximum (LGM) phase, in lower mountain areas, glaciers were present only where a sum of local factors favoured their formation, a good example being Apuseni Mountains. For the Rodnei Mountains the highest of Eastern Carpathians, a 5-km long glacier descended to 1000 m on Pietroasa Valley, corresponding to an equilibrium-line altitude (ELA) at 1340 m, the frontal moraines being between 26.6±2.4 and 18.3±1.6 ka. On the volcanic caldera’s walls of Calimani Mountains, small cirque and valley glaciers were present, and the upper conglomeratic structural plateau of Ceahlau Mountains was occupied by a small plateau glacier. In the Southern Carpathians in the Retezat Mountains, around 21±0.8–1.5 ka 10Be ages, the glaciers descended to 1000–1050 m during LGM. The Pietrele glacial complex covering an area of 27.3 km2, and the corresponding ELA was at 1646 m. The planation surfaces, a true peneplain, ubiquitous above 1800 m in Godeanu, Ţarcu, Cindrel, Lotrului, and Surianu Mountains and the marginal parts of the Retezat, Iezer, and Fagaras Mountains favoured the development of plateau glaciers associated with conical glaciers and/or small ice caps.

The Montes de Leon (northwest Spain) include the Aquilanos Mountains (2142 m), the Teleno Mountains (2182 m), and the Sierra de la Cabrera (2121 m), which are Paleozoic mountains with a predominance of slate and quartzite. During the maximum glacial advance, 94 small cirque and valley glaciers (up to 9 km long) occupying c. 116 km2 were formed in this area. Although the glacial development was similar in the three mountain ranges, the conservation of the landforms is very uneven. On the western slope of La Cabrera and in the Aquilanos Mountains, the steep slope and the greater presence of slate favored erosion, and only a few moraines have been preserved, although cirques and troughs are still present. The preserved moraines in the Teleno and the east of La Cabrera (Vizcodillo) present a less steep gradient, allowing us to observe three glacial stages. The first two show similar development, with glaciers occupying the headwaters of the valleys. The third appears in the highest and best-oriented cirques, with moraines over 1700 m. Some of the moraines were excavated for gold in Roman times, and others have been destroyed by current-day slate mining.

Glacier-erosion rates range across orders of magnitude, and much of this variation cannot be attributed to basal sliding rates. Subglacial till acts as lubricating ‘fault gouge’ or ‘sawdust’, and must be removed for rapid subglacial bedrock erosion. Such erosion occurs especially where and when moulin-fed streams access the bed and are unconstrained by supercooling or other processes. Streams also may directly erode bedrock, likely with strong time-evolution. Erosion is primarily by quarrying, aided by strong fluctuations in the water system driven by variable surface melt and by subglacial earthquakes. Debris-bed friction significantly affects abrasion, quarrying and general glacier flow. Frost heave drives cirque headwall erosion as winter cold air enters bergschrunds, creating temperature gradients to drive water flow along premelted films to growing ice lenses that fracture rock, and the glacier removes the resulting blocks. Recent subglacial bedrock erosion and sediment flux are in many cases much higher than long-term averages. Over glacial cycles, evolution of glacial-valley form feeds back strongly on erosion and deposition. Most of this is poorly quantified, with parts open to argument. Glacial erosion and interactions are important to tectonic and volcanic processes as well as climate and biogeochemical fluxes, motivating vigorous research.

International audience; The aim of this work is to study the process of transformation of debris-free mountain glaciers into debris-covered glaciers and rock glaciers, and to examine the factors driving diverging evolution in similar glacial systems. The study area is the Hofsdalur valley, in the Trollaskagi peninsula (northern Iceland), where several cirques host a great diversity of glaciers and rock glaciers as well as various glacial landforms. Four adjacent cirques have been analysed through a multidisciplinary approach: geomorphological analysis, boulder surface displacement tracking, quantification of recent glacier changes, three dimensional palaeoglacier reconstruction, equilibrium-line altitude calculations and relative and direct dating methods applied to surface boulders. Dating methods included in situ Cl-36 cosmic-ray exposure dating, Schmidt hammer weathering measurements and lichenometric dating. The results confirm that glaciers in Hofsdalur followed an evolution pattern similar to that observed in other cirques in the Trollaskagi peninsula. During the Younger Dryas (12.9-11.7 ka) many of those cirques hosted debris-free glaciers, whose retreat started in the early Holocene. Distinct retreat dynamics and cirque floor elevation conditioned the subsequent glacial evolution. In some Trollaskagi cirques, the ice completely covered the headwalls, which consequently did not supply debris onto the glacier surface, which remained debris-free. In most of these cirques, however, glacier retreat enhanced paraglacial processes and the ice-free cirque walls generated a high debris supply onto the glacier surface. As a result, the glaciers evolved towards debris-covered glaciers or rock glaciers, depending on the local topographical setting. In the lower cirques they collapsed immediately after their formation. At higher altitudes, above the lower permafrost limit, these ice-cored landforms have survived until the present day, but they have been stagnant since the Holocene Thermal Maximum, while the heads of these cirques have hosted debris-free glaciers during the Late Holocene.

Understanding natural climate variability is a fundamental goal of paleoclimate science. Temperate mountain glaciers are sensitive to climate variability, changing volume, and thus thickness and length, in response to changes in temperature and precipitation. Glaciers deposit moraines at their margins, which if well-preserved may provide evidence of glacier length fluctuations following glacial retreat. Therefore mountain glaciers can be used as proxies to investigate past climatic changes, offering the potential to reconstruct the timing and magnitude of natural climate variability and paleoclimate for the former glacier extent(s). This study applies methods of detailed geomorphological mapping and cosmogenic 10Be surface exposure dating to establish a high-precision moraine chronology and examine the timing and magnitude of glacier length changes at Rocky Top cirque. A quantitative reconstruction of paleoclimate for the identified former glacier extents was produced using an equilibrium-line altitude (ELA) reconstruction method and application of a temperature lapse rate. Findings show a clear pattern of glacial retreat at the end of the Last Glacial Maximum, with exposure ages from moraine boulders successfully constraining the timing of five distinct periods of glacier readvance or standstills. The most recent glacial event at Rocky Top cirque occurred between 17342 ± 172 yrs BP and during this period the ELA was depressed by 611 m. The second innermost moraine produced an indistinguishable age of 17196 ± 220 yrs BP and had an ELA depression of 616 m, indicating rapid glacial retreat. Progressively older moraines produced surface exposure ages of 18709 ± 237 and 19629 ± 308 yrs BP, with ELA depressions of 618 and 626 m respectively. The oldest moraine of 34608 ± 8437 yrs BP had insufficient geomorphic constraint to produce an ELA. Paleoclimate reconstruction results suggest that a best estimate of paleotemperature at the time of moraine formation (~19-17 ka) was between 3.2 ± 0.8 to 3.3 ± 0.8°C cooler than present-day. Net retreat of the former glacier is consistent with other similar moraine chronologies from the Southern Alps, which supports the regional trend and suggests that glaciers in the Southern Alps responded to common climatic forcings between ~19-17 ka.

The ice-cored Galena Creek Rock Glacier, Wyoming, USA, has been the subject of a number of studies that sought to determine the origin of its ice. We present new observations of the rock glacier's internal structure from ground-penetrating radar to constrain ice and debris distribution and accumulation. We imaged dipping reflectors in the center of the glacier that are weak and discontinuous, in contrast to strong reflectors toward the edge of the cirque beneath large debris-avalanche chutes. These reflectors form a network of concave-up, up-glacier dipping layers. We interpret these as englacial debris bands formed by large debris falls buried by subsequent ice and snow accumulation. They are discontinuous where ice outpaces debris accumulation, but with sufficient debris accumulation an interleaved pattern of ice and debris layers can form. We propose a model in which the ice in these interleaved layers is snowfall preserved by debris-facilitated accumulation. Large debris falls that occur in early spring bury sections of the snowpack, which are then preserved through summer and incorporated into the rock glacier body over time. This study highlights the importance of sequential accumulation of ice and debris for understanding the dynamics of rock glaciers and debris-covered glaciers.

Outside the Alps, the Sierra Nevada is probably the best studied European massif with respect to its past and current environmental dynamics. A multi‐approach research program started in the early 2000s focused on the monitoring of frozen ground conditions in this National Park. Here, we present data on the thermal state and distribution of permafrost and seasonal frozen ground in different sites across the highest areas of the massif. New results confirm the absence of widespread permafrost conditions, with seasonal frost prevailing above 2500 m. Small permafrost patches have been only detected in glaciated areas of the Veleta and Mulhacen cirques during the Little Ice Age at elevations of 3000–3100 m. The remnants of those glaciers are still preserved under the thick debris layer covering the cirque floors. Geomatic and geophysical surveying of a rock glacier existing in the Veleta cirque, together with the monitoring of soil temperature at different depths, have revealed permanently frozen conditions undergoing a process of degradation. In the rest of the massif, a seasonal frost regime prevails, even at the highest plateaus at 3300–3400 m, where annual soil temperatures average 2.5°C. The monitoring of soil temperatures in other different periglacial features has also revealed positive average values ranging between 2°C (inactive sorted‐circles) and 3–4°C (inactive and weakly active solifluction lobes). Consequently, we conclude that the present‐day climatic regime does not allow the existence of permafrost in the Sierra Nevada, and environmental dynamics is controlled by the intensity and duration of seasonal frost in the ground.

Producción Científica, Rock glaciers are one of the most important features of the mountain permafrost in the Pyrenees. La Paúl is an active rock glacier located in the north face of the Posets massif in the La Paúl glacier cirque (Spanish Pyrenees). This study presents the preliminary results of the La Paúl rock glacier monitoring works carried out through two geomatic technologies since 2013: Global Navigation Satellite System (GNSS) receivers and Terrestrial Laser Scanning (TLS) devices. Displacements measured on the rock glacier surface have demonstrated both the activity of the rock glacier and the utility of this equipment for the rock glaciers dynamic analysis. The glacier has exhibited the fastest displacements on its west side (over 35 cm yr-1), affected by the Little Ice Age, and frontal area (over 25 cm yr-1). As an indicator of permafrost in marginal environments and its peculiar morphology, La Paúl rock glacier encourages a more prolonged study and to the application of more geomatic techniques for its detailed analysis., Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CGL2015-68144-R), Junta de Extremadura - Fondo Europeo de Desarrollo Regional (project GR10071)

Following pioneering work in Norway, cirque glaciers have widely been viewed as rigidly rotating bodies. This model is incorrect for basin-filling cirque glaciers, as we have demonstrated at West Washmawapta Glacier, a small glacier in the Canadian Rocky Mountains. Here we report observations at the same glacier that assess whether complex temporal variations of flow also occur. For parts of three summers, we measured daily displacements of the glacier surface. In one year, four short-duration speed-up events were recorded. Three of the events occurred during the intervals of warmest weather, when melt was most rapid; the fourth event occurred immediately following heavy rain. We interpret the speed-up events as manifestations of enhanced water inputs to the glacier bed and associated slip lubrication by increased water volumes and pressures. No further speed-ups occurred in the final month of the melt season, despite warm temperatures and several rainstorms; the dominant subglacial water system likely transformed from one of poorly connected cavities to one with an efficient channel network. The seasonal evolution of hydrology and flow resembles behaviors documented at other, larger temperate glaciers and indicates that analyses of cirque erosion cannot rely on simple assumptions about ice dynamics.

Accordingly, the present study is aimed at investigating quaternary climate changes in Binalod Heights. To identify glacial effects, Morphic indices, field evidence and effects, climatic evidence, and (laboratory) experimental analysis were employed. Determining the permanent snow line in the region was conducted using the Right Method and 65 cirques which are considered as much enriched feeding resources for the formation an ice cover in the region. The expansion of settlements in the region are lower than the permanent snow life is more accumulated than above the border of the permanent snow line. This issue indicates that refrigeration cells do not have the ability to create civil nuclear. Regarding quaternary climate changes and the gradual warming of the climate, the initial core of the City of Mashhad ranges from the center of the Kashf rood River to northeastern heights of Binalod. In addition, the existence of glacial cirques in heights as an important factor in feeding refrigerating conditions has been effective on the expansion of urbanization of Mashhad in the past time. Our new geomorphological mapping and landsystem reconstructions provide an important insight into the response of temperate Binalod glaciers to rapidly-warming climate

co-auteur étranger; International audience; We conducted a petrological study of the layered gabbros and peridotites outcropping in the cirque of Salazie, combining field investigations, geochemistry, petrography and, mineralogy to constrain the magmatic evolution of Piton des Neiges volcano (La Réunion). Three new hectometer-long outcrops are reported here (Sites 1, 2 and 3) in addition to the gabbroic series (hereafter named Site 4) previously described in the literature. The Sites 1 and 2 are located in the upper parts of the Mât River and show dunite and wehrlite units with no apparent foliation, lineation, or layering. The Sites 3 and 4 are located in the lower parts of the river and are made of olivine-gabbro, gabbro and ferrogabbro units showing marked foliation and lineation, and abundant layering. The mean composition of primary phases varies between Sites 1–2 and Sites 3–4: Fo89.5 to Fo69.8 in olivine, Mg# of 90 to 69 in clinopyroxene, and Mg# of 44 to 0 in Cr-spinel, titanomagnetite and, ilmenite, respectively. Here we show that the layered gabbros and peridotites exposed at the four sites represent multiple levels of magma storage. Based on the results of previous gravimetric studies and a drill hole related to geothermal exploration, we propose that the gabbroic series belongs to a magmatic system predating the building of Piton des Neiges and centered underneath the cirque of Salazie. The high volume of erupted materials in the NE quadrant of the volcanic edifice, and the southward magmatic flow direction in the layered gabbros suggest that the initial eruptive center of Proto-Piton des Neiges was above the cirque of Salazie, ~3 km north of the present-day summit. The landscape of Piton des Neiges may have changed when its NE flank experienced a major lateral collapse, after complete solidification of the gabbroic bodies. The magmatic activity, then, shifted southward after the flank collapse. Finally, we suggest that peridotites outcrops are associated with the present-day Piton des Neiges.

Cirques are typical erosional landforms of glaciers and have been used as bases for paleoclimate and paleoenvironment reconstruction and for understanding the interactions between glacial erosion, climate, and topography. The availability of high-resolution digital elevation models (DEMs) provides the opportunity to map large populations of cirques for regional and global scale analysis. However, cirque outlines are still mainly determined based on manual digitization, which is time consuming and labor intensive. This paper introduces an automated method to recognize and delineate cirques using DEMs based on a series of hydrological and morphological analyses, including delineating stream network, filtering streams, determining potential cirque threshold points, and delineating cirque outlines. A semi-automated tool is also developed based on user-specified threshold points or cross sections. The related tools are coded in python and imported into ArcGIS as a toolbox, AutoCirque, with user friendly interfaces. Comparison in a test area of the eastern Tian Shan, China, indicated that the population statistics are relatively consistent between manually digitized and auto-delineated cirques. Detailed comparisons for 11 selected cirques indicated that the AutoCirque-delineated and manually digitized cirque outlines are similar in shape with an average boundary offset of approximately one DEM cell size (30 m) and a 70–90% overlap-fit percentage. The derived cirque metrics are also similar, especially for elevation, slope, and aspect related metrics. This toolbox can significantly speed up the analytical processes, remove the subjectivity in delineating cirque outlines, and allow for the comparison of cirque morphology and metrics at regional and global scales.

The objective of this study was to assess whether it is possible to obtain a comprehensive record of the last deglaciation from the small Pena Negra glacial cirque in a marginal mountain range in the Iberian Range (northern Iberian Peninsula). The cirque is located in Sierra Cebollera, at an elevation slightly over 2000 m a.s.l. in the divide, and has relatively low elevational difference between its uppermost and lowest parts. The Pena Negra glacial cirque was selected because of the presence of several lateral moraines indicating the occurrence of a glacial tongue of 1.8 km length and a small rock glacier, enabling identification of the main glacial stages that affected the paleo-evolution of the glacier. Using cosmogenic exposure dating techniques and geomorphological mapping it was possible to reconstruct the historical Pena Negra glacier and to distinguish: (i) the maximum ice extent (MIE) at approximately 18–20 ka, coinciding with the Global Last Glacial Maximum (GLGM), although the occurrence of a previous stage was not ruled out; (ii) a stage of glacial re-advance at 16–17 ka, coinciding with the Oldest Dryas, followed by rapid ice melting; (iii) the development of a rock glacier in a minor structural cirque near the headwall at 14–15 ka, when paraglacial processes were probably dominant; and (iv) evidence of ice melting in the uppermost cirque at 13.5 ka. Study of the Pena Negra glacier revealed the history of a minor valley glacier affected by distinct stages, including the formation of a small rock glacier in the final phases of deglaciation. No evidence of a Younger Dryas re-advance was found.

The China&ndash, Pakistan Economic Corridor (CPEC), a key hub for trade, is susceptible to glacial lake outburst floods. The distributions and types of glacial lakes in the CPEC are not well documented. In this study, cloud-free imagery acquired using the Landsat 8 Operational Land Imager during 2016&ndash, 2018 was used to delineate the extent of glacial lakes in the mountainous terrain of the CPEC. In the study domain, 1341 glacial lakes (size &ge, 0.01 km2) with a total area of 109.76 &plusmn, 9.82 km2 were delineated through the normalized difference water index threshold method, slope analysis, and a manual rectification process. On the basis of the formation mechanisms and characteristics of glacial lakes, four major classes and eight subclasses of lakes were identified. In all, 492 blocked lakes (162 end moraine-dammed lakes, 17 lateral moraine-dammed lakes, 312 other moraine-dammed lakes, and 1 ice-blocked lake), 723 erosion lakes (123 cirque lakes and 600 other erosion lakes), 86 supraglacial lakes, and 40 other glacial lakes were identified. All lakes were distributed between 2220 and 5119 m a.s.l. At higher latitudes, the predominate lake type changed from moraine-related to erosion. From among the Gez, Taxkorgan, Hunza, Gilgit, and Indus basins, most glacial lakes were located in the Indus Basin. The number and area of glacial lakes were larger on the southern slopes of the Karakoram range.

The Carpathian island-type glaciokarst has a great potential of preserving signals of past environments, archived in cave deposits like speleothems and clastic infills.Wepresent here the geomorphology and structural control of several relict alpine caves and the surrounding glaciated marble karst in the Făgăraș Mountains. Four truncated and partially unroofed caves remained on the ridge-top of Mușeteica Mountain, above the glacial cirque, while a ponor cave that developed on the cirque bottom could be related to the Last Glacial Period. Structuralmeasurements and cave morphology showed that the conduits formed at the intersection of foliation planes and tectonic fractures on the NE-SWand NW-SE directions. Cave development reflects three speleogenetic stages: 1) textureand fabric-controlled dissolution and distension; 2) structurally-controlled breakdown; and 3) truncation, unroofing, and cave infillingwith sediments. Slowdiffuse dissolutionwas typical for the ridge-top caves,whereas M1 Cave developed by pressure flow. Further, we report the first U\\Th speleothem ages, related to the evolution of alpine caves and island glaciokarst in the South Carpathians during the Middle and Late Pleistocene. Dating results show a minimum estimated age of ~560 ka for the ridge-top caves, and that speleothem deposition met optimal conditions only during warmer periods, largely corresponding to interglacials. Stable carbon isotope values in speleothems range between−9.96‰and−4.11‰, indicating the presence of plant and soil organic activity at the time of deposition. In total, five speleothem growth phases were distinguished during the last ~560 ka. We excavated the sediment infill of a ridge-top doline down to a 2-mdepth. Radiocarbon dating revealed that it was deposited during the Late Holocene, and preliminary pollen analysis identified a plant assemblage dominated by grasses. Using the relationships between karst development, glaciation, and cave sedimentary archives,we present a time slice chronology of alpine landscape evolution at N560 ka, ~400 ka, ~330 ka, the Last Glacial Period (70–12 ka), and the Late Holocene. Our geomorphological, isotopic, and geochronological results also support the existinghypothesis that the South Carpathians may have experienced at least two glacial phases during the Pleistocene. Glacial erosion rate during the Last Glacial Period, and most likely during the penultimate glaciation, averages around 0.6 mm yr−1.

Cirques are characteristic landforms in high alpine environments with flat cirque floors flanked by steep headwalls. From a rock-mechanical perspective, rock walls are assumed to adjust over time according to their internal rock mass strength, which is determined by a number of factors including e. g. intact rock strength and fracture system characteristics. However, temperatures permanently below freezing as well as glacier coverage keep cirque headwalls stabilised so that slope inclination can evolve during glaciation that is far beyond strength equilibrium. When cirque headwalls deglaciate, the relative importance of rock mass properties increases drastically as they precondition rock slope instability. Cataclinal headwalls, where major fracture sets dip out of the slope, are rated as unstable and usually respond rapidly to glacier retreat. Anaclinal headwalls with in-dipping fracture sets in contrast respond delayed and probably less drastically. To date, a systematic assessment of the predisposition of cirque headwalls for rock slope instability following deglaciation is lacking. We aim to tackle this lacking by a systematic regional analysis of predisposition factors using GIS tools. For the central Hohe Tauern Range, Austria, regional datasets are available for the most important preconditioning factors including topography (digital elevation model), geology (digital geological map), glacier extent (digital glacier inventory), and permafrost distribution (PERMAKART 3.0). We combined geomorphometric analyses with geotechnical data to locate and evaluate the sensitivity of glacier headwalls to rock slope instability using GIS and object-based analysis techniques. Our results show that a vast majority of the headwalls identified can be divided by a significant convexity in the slope profile curvature into a larger, upper and a lower, steeper headwall section (> 60°). The lower limit of the steeper section is marked by a significant concavity in the slope profile curvature, which is commonly known as the schrundline. Assuming that the convex transition between steeper and flatter headwall section constitutes the upper limit of enhanced headwall retreat e. g. by periglacial weathering inside the bergschrund, we further address this headwall section as the schrundwall. Geotechnical data (foliation dip and direction) has been digitalised and interpolated in a yet oversimplified manner, to distinguish headwalls into cataclinal, anaclinal and orthoclinal slopes. Slope inclination and foliation dip has been interrelated to identify e. g. particularly sensitive overdip slopes. First results show that anaclinal and orthoclinal as well as cataclinal headwalls are quite common features in the study area. However, overdip slopes with steeply (30°-60°) outdipping foliation are almost exclusively found in schrundwall sections. The persistence of steep overdip schrundwalls may be related to permafrost occurrence, which is subject to further analysis. Our approach, applied to modeled subglacial topography, may be of great value to anticipate future paraglacial instabilities in glacier headwalls.

Over the past 150 years almost half of the glacier volume disappeared in the European Alps. Besides glacier retreat, ice surface lowering reflects much of the volume loss and uncovers the adjacent rockwalls. In steep glacial cirques, this process exposes rock to atmospheric conditions for the very first time in many millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high-resolution is missing and the proportional contributions of low-, mid- and high magnitude rockfalls have remained poorly constrained. We use terrestrial LiDAR to establish a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn). During six-year monitoring (2011-2017) 78 rockwall scans were acquired. Overall, we registered 632 rockfalls ranging from 0.003 to 879.4 m³, which concentrate along pre-existing structural weaknesses. 60 % of the rockfall volume detached from less than ten vertical meters above the glacier surface, indicating enhanced rockfall over tens of years following deglaciation. Antecedent rockfall preparation is assumed to start when the rockwall is still ice-covered: Inside the Randkluft (gap between cirque wall and glacier) sustained freezing and sufficient water supply likely cause enhanced weathering and high plucking stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into perennially frozen bedrock, likely contributing to the observed paraglacial rockfall increase close to the glacier surface. Observed mean cirque wall retreat of 1.9 mm a-1 ranks in the top range of reported values and is mainly driven by enhanced rockfall from the lowermost, freshly deglaciated sections of the investigated rockwalls. Rockfall magnitude-frequency distribution, which has never been quantified before for deglaciating cirques, follows a distinct negative power law distribution over four orders of magnitude. Magnitude-frequency distributions in glacier-proximal and glacier-distal rockwall sections differ significantly due to an increased occurrence of large rockfalls in recently deglaciated areas. The present study thus demonstrates how recent climate warming shapes glacial landforms, controls spatiotemporal rockfall variation in glacial environments and indicates an exhaustion law over decades for rockfall activity immediately following deglaciation crucial for future hazard assessments.

Cirque erosion contributes significantly to mountain denudation and is a key element of glaciated mountain topography. Despite long-standing efforts, rates of rockwall retreat and the proportional contributions of low-, mid- and high magnitude rockfalls have remained poorly constrained. Here, a unique, terrestrial LiDAR-derived rockfall inventory (2011–2017) of two glaciated cirques in the Hohe Tauern Range, Central European Alps, Austria is analysed. The mean cirque wall retreat rate of 1.9 mm a−1 ranks in the top range of reported values and is mainly driven by enhanced rockfall from the lowermost, freshly deglaciated rockwall sections. Retreat rates are significantly elevated over decades subsequent to glacier downwasting. Elongated cirque morphology and recorded cirque wall retreat rates indicate headward erosion is clearly outpacing lateral erosion, most likely due to the cataclinal backwalls, which are prone to large dip-slope failures. The rockfall magnitude-frequency distribution – the first such distribution derived for deglaciating cirques – follows a distinct negative power law over four orders of magnitude. Magnitude-frequency distributions in glacier-proximal and glacier-distal rockwall sections differ significantly due to an increased occurrence of large rockfalls in recently deglaciated areas. In this paper we show how recent climate warming shapes glacial landforms, controls spatiotemporal rockfall variation in glacial environments and indicates a transient signal with decadal scale exhaustion of rockfall activity immediately following deglaciation crucial for future hazard assessments.

Rila Mountain in Southwest Bulgaria is the highest mountain on the Balkan Peninsula. During the Pleistocene ice ages, large ice shields covered higher parts of the mountain forming cirques and through glacier valleys. Maritsa Cirque Complex is the through head of one of the most powerful glaciers, carved out in the mountain. Since it was nominated for a geosite of esthetic and scientific value within Geopark Rila, in order to improve, precise, and unify the method of characterization and presentation of geomorphosites in alpine environment, it was chosen as an example description to serve as a model for characterization of the other geomorphosites in the geopark. Maritsa Cirque Complex is well outlined in its natural boundaries on an area of 5.29 km2 including five composite cirques: Maritsa, Trionite, Preslap, Malak Bliznak, and Mancho. The cirque complex is incised in the Eocene granite of the Musala Body of the largest batholith on the Balkans – the Rila-West Rhodopes Batholith. The Maritsa Cirque is the deepest Rila’s cirque with a diameter of 1500 m and displacement of 572 m between its bottom and the highest peak Musala (2925 m). In the middle of it, a younger cirque is incised with a diameter of 700 m, in which two tarns (Maritsa Lakes) are formed. The other cirques are smaller and higher, hanging over the main valley. The glacial and post-glacial deposits are represented by bottom moraines and supraglacial scree slopes, representing clusters of angular granite blocks and boulders on the slopes of the cirques and glacier valley. There are large scree cones at the base of the avalanche furrows on the cirques walls which are the product of frost weathering in the active periglacial alpine belt of Rila. The cirque complex is deeply incised into the Early Miocene Kapatnik denudation surface, the highest Rila’s peneplain elevated at 2400 m above sea level, which shaped the rounded Rila’s ridge before the Ice Ages. The present slope of this surface in Zavrachitsa area shows that the highest peak of Rila during the Pleistocene was just above the Maritsa Cirque and the surrounding peaks – Musala, Maritsa Chal, Mancho, and Twin Peaks – were situated on its slopes. The reconstruction of the Pleistocene paleorelief based on a simple GIS analysis of the modern relief shows that the height of the dome-shaped Rila’s top peak Paleo Musala before the Pleistocene glaciations was more than 3000 m. Easily accessible and well-preserved glacial and post-glacial landscapes provide an excellent opportunity for demonstrating the geological processes and destructive glacial activity that shaped the highest mountain on the Balkans. The continental significance of this geomorphosite is complemented by the remarkable petrographic diversity of the granitoids of the Rila-West Rhodopes Batholith and metamorphic rocks contained therein, intersected by numerous pegmatite, aplite and quartz veins, vein-like granite bodies, diorite, and granite porphyry veins, suitable for illustrating crystallization process, magmatic/metamorphic structures, and textures and demonstrating the principle of the crosscutting relationships in geology. Standard geosite’s characterization in the form of scientific dossiers, including the most important information about the genesis and geoconservation features, will provide a reliable basis for estimation and comparison of their individual merits necessary for inclusion in the geosites inventory of Geopark Rila. It will contribute to the assessment and promotion of the geosites through development of itineraries linking geosites in alpine environment with appealing information panels containing well-interpreted scientific information directed to the general public.

Through a detailed geomorphological study, including thourough mapping of the geomorphic features as well as Be-10 Cosmic-Ray Exposure (CRE) dating, the geomorphological evolution of the Mulhacen cirque since the maximum ice extent of the last glacial cycle until nowadays was determined. This glacial cirque is shaped on the northern face of the Mulhacen peak (3479 m a.s.l. 37 degrees 03'12 ' N/3 degrees 18'41 ' W), Sierra Nevada, southern Spain. It includes several depositional and erosional glacial landforms that allowed reconstructing its environmental evolution since the last glacial cycle. Furthermore, the sequence of glacial oscillations from this site was compared to that of other cirques of the massif, evidencing that: (i) new glaciers formed in these cirques during the Younger Dryas (YD), and (ii) disappeared at 11.7 +/- 1.0 ka. Depending on the altitude, orientation and height of the cirque walls, the final deglaciation of the cirques generated a diversity of landscapes, including a wide range of glacial and periglacial landforms, such as polished surfaces, sequences of moraines, proto-rock glaciers or large rock glacier systems. No glaciers existed in the Sierra Nevada during the Middle Holocene. Only the cirques whose summits exceed 3300 m, are north-exposed and whose walls exceed 300 m high (i.e. Mulhacen and Veleta) hosted glaciers during Neoglacial phases, including the Little Ice Age (LIA) (approx.1300-1850 CE). During these periods, climate oscillations favoured the formation of small glaciers in these cirques, which generated large moraine systems with either one polygenic ridge or a sequence of spaced frontal arcs. The existence of glaciers impeded the formation of permafrost-related landforms, such as rock glaciers and protalus lobes until the end of the LIA, when they started to form. These results are compared with the deglacial evolution in 55 cirques from Iberian mountains as well as from glacial cirques from other mid-latitude mountains and subpolar regions. The chronology of their deglaciation as well as the landforms generated during glacial retreat followed similar patterns, with no significant differences at regional scale. For each mountain range, the geomorphological diversity existing in each cirque depends on the local topographic characteristics although they formed during the same climatic phases.

International audience; In this study, we present a new glacial chronology based on 20 in situ-produced 36Cl-based cosmic ray exposure datings from moraine boulders and bedrock from the Throne of Zeus (TZ) and Megala Kazania (MK) cirques on Mount Olympus. The 36Cl derived ages of glacial landforms range from 15.6 ± 2.0 to 0.64 ± 0.08 ka, spanning the Late-glacial and the Holocene. The Late-glacial, recorded in both cirques, is partitioned in three distinct phases (LG1-3): an initial phase of moraine stabilization at 15.5 ± 2.0 ka with subsequent deglaciation starting at ∼14 ka (LG1), followed by a shift to marginal conditions for glaciation at 13.5 ± 2.0 ka (LG2), sustained by large amounts of wind-blown snow, despite regional warming. Glacial conditions returned at 12.5 ± 1.5 ka (LG3) and were characterized by low air temperatures and glacier shrinking. The Holocene glacial phases (HOL1-3) are recorded only in the MK cirque, likely due to its topographic attributes. An early Holocene glacier stillstand (HOL1) at 9.6 ± 1.1 ka follows the regional temperatures recovery. No glacier activity is observed during the mid-Holocene. The Late Holocene glacier expansions, include a moraine stabilization phase (HOL2) at 2.5 ± 0.3 ka, during wet conditions and solar insolation minima, while (HOL3) corresponds to the early part of the Little Ice Age (0.64 ± 0.08ka). Our glacial chronology is coherent with glacial chronologies from several cirques along the northeast Mediterranean mountains and in pace with numerous proxies from terrestrial and marine systems from the north Aegean Sea.

Mountain glaciation involves the erosion of cirques and troughs, which increase steep slopes but also produce gentle slopes in cirque floors and trough floors. This is expected to increase the variability of slope gradients at related altitudes. Taking a whole mountain range, its distributions of altitude and slope can be analysed to establish a signal of glacial modification. Frequency distributions of altitude (hypsometry) and gradient (clinometry) alone do not seem adequate. Taking these two variables together – hypsoclinometry, plotting slope gradient against altitude – is more promising. Frequency distributions of slope gradient at different altitudes are exemplified here for mountain ranges in British Columbia and Romania, together with altitudinal variations of steep or gentle slopes. Cirque headwalls give the clearest morphometric signature of glaciation. Steep (especially the steepest) slopes are concentrated at cirque altitudes, increasing mean, median, standard deviation (SD) and inter-quartile range (IQR) of gradients, especially above cirque floors. There is only a small increase in SD and IQR at cirque floor altitudes. Hypsometric maxima and increased proportions of gentle slopes at cirque floor altitudes are clear only in mountain ranges densely occupied by cirques. This relates to the small proportion of each cirque (about 28%) occupied by the floor. Concentrations of steep slope aspects in directions favoured by local glaciers provide further evidence of glacial modification. The most general morphometric effect of glaciation, however, is the increase in steep slopes at cirque headwall altitudes. Thus it is possible to rank mountain ranges by degree of glacial modification.

富山市の太郎兵衛平〜雲ノ平の高山・亜高山帯において，（1）地質・地形，（2）動物，（3）植物の調査を行った．（1）地質・地形では，板状節理が発達する安山岩や溶岩台地などの火山地形を雲ノ平で確認した．また，氷河地形として，薬師岳の南東に伸びる稜線の西斜面に発達するカールを確認した．（2）動物では，約30種の昆虫を観察した．このうちベニヒカゲ，オオルリボシヤンマ，ミヤマハンミョウ，カオジロトンボは高標高地帯を好む種であり，山岳地帯の調査ならではの結果であった．また，太郎山と祖父岳の登山道沿いでライチョウを発見した．（3）植物は，写真のEXIF情報から2300以上の植物分布データを抽出した．, The geology, topology, fauna, and flora of the alpine and subalpine zone between Tarobeidaira and Kumonotaira in Toyama city were researched. Volcanic landforms such as the lava plateau and andesite with platy joint at Kumonotaira were recognized. Cirques in the west slope of the southeast ridge of Yakushi-dake was recognized as glacial landforms.About 30 species of insects were observed during the research. In general, Erebia neriene (Böber), Aeshna crenata Hagen, Cicindela sachalinensis Morawitz, Leucorrhinia dubia (Van der Linden), Nicrophorus vespilloides (Herbst) are species observed at places with high altitudes, which were unique results of research of mountainous areas.Rock ptarmigans were observed on the trail of Taroyama and Jii-dake. And more than 2300 plant distribution data were extracted from Exif information of photographs.

We present here a more complete cosmogenic chronology of Pleistocene glacial deposits for the Wind River Range, Wyoming, USA. Fifty-one new and thirty-nine re-calculated 10Be and 26Al exposure ages from Sinks and North Fork canyons, Stough Basin, Cirque of the Towers and the Temple Lake valley allow us to more tightly constrain the timing and sequence of glacial alloformations in the southern portion of the range.\ud \ud Moraines, diamicts and bedrock exposures here have previously been correlated with as many as five Pleistocene and four Holocene glacial events. Exposure ages from Pleistocene alloformations associated with trunk glaciers in Sinks Canyon and North Fork Canyon generally confirm earlier age estimates. Cosmogenic radionuclide (CRN, 10Be and 26Al) ages from moraines and striated bedrock surfaces previously mapped as Pinedale correspond to MIS2, while boulder exposure ages from moraines mapped as Bull Lake correspond generally to MIS5-MIS6. Geomorphic data from a moraine previously mapped as Younger pre-Sacagawea Ridge appears to correspond most closely to the Sacagawea Ridge glacial episode (MIS-16), but the uncertainty of a single 10Be exposure age suggests the unit could be as young as MIS-10 or as old as MIS-18. Boulders from a diamict on Table Mountain previously reported as Older pre-Sacagawea Ridge yield two 10Be exposure ages that suggest the presence of Early Pleistocene glacial activity here possibly older than 1–2 Ma (>MIS-30).\ud \ud Bedrock exposure ages within Sinks Canyon suggest the Pinedale valley glacier had retreated from the floor of Sinks Canyon to above PopoAgie Falls by ca. 15.3 ka. Cirque glaciers in Stough Basin appear to have retreated behind their riegels by ca. 16 ka, which suggests the cirque glaciers were decoupling across their riegels from the valley glaciers below at this time, prior to their readvance to form Lateglacial moraines.\ud \ud New 10Be boulder exposure ages from moraines previously correlated to the Temple Lake and Alice Lake allostratigraphic units in the cirques of Stough Basin and Cirque of the Towers show general equivalence to the stadial event just prior to the onset of the Bølling interstadial (17.5–14.7 ka) and to the Intra-Allerød Cold Period-Younger Dryas stadial phase (13.9–11.7 ka), respectively. From this evidence, the Temple Lake Alloformation of the Wind River Mountains now should correspond to the INTIMATE GS-2.1a (Oldest Dryas) stadial event while the Alice Lake Alloformation should correspond to the INTIMATE GS-2 stadial (IACP-Younger Dryas). Thus, we consider that evidence no longer exists for early-to mid-Holocene glacial events in the southern Wind River Range.

On the Pico Cuiña cirque, Sierra de Ancares (León, Spain), the seasonal snow cover undergoes both slow and rapid mass displacements. Push associated with moving snow is responsible for an intense geomorphological activity, which is characterised by the plucking and transport of fragments of the bedrock, the abrasion of rock surfaces and the deposition of the mobilized material. Pronival ramparts are the most characteristic accumulation geoform created by pushing snow. Its study enabled us to verify the functionality of the nival processes and to prove the relative antiquity of some of them. The use of lichenometric techniques, based on the prior construction of a growth curve for lichens of the Rhizocarpon subgenus, has made possible to date sectors of the pronival ramparts. Lichenometric dates show a series of events of geomorphic activity of the snow cover fitting chronologically within the so-called Little Ice Age. It can be deduced from the observation of the current geomorphic dynamics of the snow cover that, although Little Ice Age temperature decrease might be important, particularly in the summer, the role of the variations in snow precipitation must be also taken into consideration. En el circo del Pico Cuiña, Sierra de Ancares (León, España), la cubierta nival estacional experimenta desplazamientos en masa que le confieren una notable capacidad de empuje basal. El empuje nival es, a su vez, responsable de una intensa actividad geomorfológica, caracterizada por el arranque y el transporte de fragmentos del substrato, la abrasión de superficies rocosas y la deposición del material movilizado. Las crestas o caballones de posición pronival (pronival ramparts) constituyen las geoformas de acumulación más características debidas al empuje nival. Su estudio, desde finales del pasado siglo, ha permitido comprobar la funcionalidad de los procesos que las originan, así como constatar la relativa antigüedad de alguna de estas geoformas. La utilización de técnicas liquenométicas, a partir de la elaboración previa de una curva de crecimiento de los líquenes del subgénero Rhizocarpon, ha permitido realizar una datación de distintos sectores de las crestas pronivales. Las dataciones han evidenciado una cronología de eventos de actividad geomorfológica del manto nivoso que se encuadra temporalmente dentro de la llamada Pequeña Edad de Hielo. Del estudio de la dinámica geomorfológica actual del manto nivoso y particularmente de su capacidad para crear y modificar crestas pronivales, puede deducirse que, en el caso de los eventos reconocidos como pertenecientes a la Pequeña Edad de Hielo, aunque pueda ser importante el descenso de las temperaturas, sobre todo las estivales, el papel de las variaciones en el aporte de nieve también debe ser considerado. This work was funded through the support of Consolidación e Estructuración 2017 GRC GI-1667-RODA, ED431C 2017/26. Xunta de Galicia, Spain SI

One of the issues that geomorphology researchers have focused on is to trace the geomorphic effects and the snow lines in the Quaternary glaciers in Iran. This research has been carried out in the valleys of the southern slopes of Alvand Kuh Mountains, namely the Serkan and Mobarakabad valleys. The equilibrium line altitude between current and ancient glaciers is one of the parameters that is used as a variation indicator of climate. There are several ways to rebuild this parameter (Ancient ELA). Equilibrium Line altitude requires the accurate knowledge of glacial geomorphic landforms and evidence. According to Kuhle, Hofer and Luis methods, providing and estimating the ancient and permanent snow lines were carried out in this research during field operations within several intervals and the glacial geomorphic evidences were identified such as circuses, sidebar moraines and terminal moraines. The six glacier subwatersheds were developed in a study area based on Kuhle, Hofer and Luis methods in which only two valleys of Serkan 3 and Mubarak Abad 3 had a high degree of accuracy in their ELA drop rate and old snow lines. It should be noted that the current snowlines of the current study area are 4400 m and 1400 m (based on the Schweitzer map). The results of the estimated snow lines for each of the six valleys are shown in Table 4. At the present study, the main of the Mobarak Abad valley area was divided to six glacial valleys which are called Serkan 1, 2, 3 and Mobarak Abad 1, 2, 3 and then several layers were provided, including cirque layers, moraine layers, primary and secondary crest layers, high crest layers, 10-meter DEM layer, highlight, different contour line layers and valleys profiles and finally, the ultimate map of glacial geomorphology of Serkan and Mobarak Abad valleys was prepared.

Cirque morphology represents the characteristics of palaeoglaciations and palaeoclimate. This study mapped and analysed 70 cirques in the central Tibetan Plateau (TP) with dominant continental climate. The results show that from northwest to southeast, cirque dimensions (i.e., length, width, and area) increase, while cirque floor altitudes decrease. A likely reason is the high precipitation rate caused by the Indian summer monsoon in the southeastern part. The diversity of cirque aspect values indicates weak or inconsistent prevailing winds during cirque development. Cirques enlarge with altitude, which might imply that cirques at high altitudes developed early and thus increased in size. Cirque aspect diversity increases with altitude from 5100 to 5600 m above sea level (asl), which indicates the capacity of high altitudes to support cirques at less favourable slopes. If altitude increases above 5600 m asl, the diversity of cirque aspect first increases and then decreases, which may be because of local topography. Mountain orientation and lithology had an effect on cirque aspect/size. Cirque numbers and sizes were compared between western, central, and eastern sectors of the Gangdise Mountains in the southern TP with those in the central TP. This comparison showed that a strengthening Indian summer monsoon can raise the value of ‘cirque density’ (i.e., cirque number per unit area), promote glacier development into valley-type, and limit cirque enlargement.

We report 80 10Be ages on 14 moraines from Irish cirques that show a previously unrecognized signal of at least eight millennial-scale fluctuations between 24.5±0.7 ka and 11.0±0.3 ka. Several moraine ages may be correlative with abrupt warming at the onset of the Bolling (14.7 ka) and the end of the Younger Dryas (11.7 ka), suggesting a forced response. Our ages also identify glacier fluctuations that occurred when regional temperatures were relatively stable. This finding is consistent with modeling results showing several hundred-meter-scale glacier fluctuations in response to interannual variability. At the same time, our composite record of cirque-glacier average equilibrium line altitudes (ELAs) shows a response to warming due to increasing greenhouse gases and summer insolation modulated by abrupt climate changes. Our new 10Be chronology thus records both forced and unforced millennial-scale glacier fluctuations superimposed on a lower frequency ELA signal of forced response to climate change.

Using high-resolution Google EarthTM images in conjunction with Landsat images, the glaciers and lakes in the Baspa basin are classified to explore the recent changes. A total number of 109 glacier...

We map glacial cirques, and analyse spatial variability in their altitude and aspect to derive a long-term, time-integrated, perspective on climate patterns during former periods of mountain glaciation (likely spanning multiple Quaternary glaciations) in Britain and Ireland. The data reveal that, although air temperatures were important, exposure to moisture-bearing air masses was the key factor in regulating sites of former mountain glacier formation, and indicate that during such periods, moisture supply was largely controlled by North Atlantic westerlies, with notable inland precipitation gradients (precipitation decreasing inland), similar to present day. In places, trends in cirque altitude may also reflect regional differences in the extent of cirque deepening, controlled by the dimensions and dynamics of the glaciers that came to occupy them. Specifically, comparatively deep cirques in coastal locations may reflect the former presence of dynamic (fed by moisture from the North Atlantic), but comparatively small, glaciers (largely confined to their cirques). By contrast, decreasing cirque depth further inland, may reflect the former presence of larger and/or less dynamic ice masses, occupying comparatively continental climatic conditions.

The Taurus Mountains of southwest Turkey are split into numerous separated ranges, of which eleven supported former glaciers. We describe cirques and related moraines in four new locations, as well as those in seven ranges where glaciation was previously known. This gives a complete inventory of the 85 cirques in southwest Turkey. These are comparable in size to those elsewhere, but narrower and often less developed. Lengths averaging 672 m are high relative to widths of 542 m. Overall axial gradients average 22.4°. Cirque floor altitudes are controlled largely by altitudes of the mountains above, but they also vary in relation to precipitation, in sympathy with ELAs (Equilibrium Line Altitudes) of former glaciers. In most ranges where glaciers were short (extending little beyond cirques), ELA can be predicted from mean mid-floor altitude. Our observations demonstrate lower ELAs than in previous literature. Both ELAs and cirque floors rise eastward in the west, and northward inland from the coast. This supports the importance of winds from the west and southwest, off the Mediterranean Sea, bringing LGM (Last Glacial Maximum) conditions wetter than present to mountains near the coast. Cirques face on average a little east of north, showing the effects of shade and differential solar radiation receipt.

The general trend of glacial retreat since the Little Ice Age has shown an acceleration during the last decades in Southern Argentine and Chilean Patagonia. The Fuegian Andes climatic records report an irregular mean annual temperature increase since 1970, with acceleration from 2015, and the Chato Glacier, as other regional cirque glaciers, has undergone a rapid ice front retreat. A detailed mapping of the proglacial area of the Chato Glacier allowed the identification of a landform assemblage related to the glacier retreat during the last decades. In this paper morphological and sedimentological features of this peculiar landform assemblage, generated in an intense glacial ablation environment, are described and the causes of their origin are discussed. Among the most remarkable landforms annual moraines, hummocky moraines, esker-like landforms, flutes, kettle ponds, dirt cones, glacifluvial deposits, pronival ramparts and collapsed moraines are found. The multitemporal analysis of the Chato Glacier retreat allowed us to interpret that most of these landforms were generated when the landscape became ice-free after 2005. The Chato Glacier cirque floor gentle slope, the thin-ice thickness and the occurrence of a rocky threshold near the glacier front would have promoted the rapid glacier thinning and the disconnection of dead ice. This context, together with the sediments and meltwater availability, would have favored the development of this landform assemblage which is ephemeral due to its high susceptibility to erosion.

The Chornohora and Svydovets massifs represent the highest part of the Ukrainian Carpathians (2061 m a.s.l.) and the north-eastmost mountain area in Europe, which was subject to mountain glaciation during the Quaternary. This region represents one of the least explored areas in terms of glacial geomorphology in Europe, which is crucial for validating the inferred zonal/meridional mode of atmospheric circulation on the continent during glacial stages. Based on new mapping of glacial landforms and sediments, we reconstruct the extent and ice-surface geometry as well as establish equilibrium line altitudes (ELAs) using the Area-Altitude-Balance-Ratio method for 40 palaeo-glaciers in the study area during the local Last Glacial Maximum (LLGM). Additionally, we list the inventory and morphometric characteristics of glacial cirques in the studied massifs (n = 77), which together with the local ELA pattern are discussed in the context of palaeo-wind directions and dominant precipitation patterns during the LGM. ELA values for the Svydovets (1401 m a.s.l.) and Chornohora (1516 m a.s.l.) massifs were much lower than those for the Rodna Mountains (1697 m) in the Northern Romanian Carpathians located 80 km to the southeast, and for the Tatra Mountains (1580 m) located 350 km to the northwest. In the Ukrainian Carpathians both glacier ELA and cirque elevations show a rising trend towards the southeast of 4 m km−1 controlled by preferential moisture transport from the northwest. This suggests that the dominant W-NW precipitation regime in effect during the LGM was similar to present-day conditions. This supports a previous glacial-geomorphologic reconstruction from the Rodna Mountains in Northern Romania and is in line with both model simulations and regional palaeo-wind proxies that show an enhanced mid-latitude North Atlantic zonal circulation pattern over central Europe during the LGM.

International audience; The Central Pyrenees hosted a large ice cap during the Late Pleistocene. The cirques under relatively low-altitude peaks (2200–2800 m) include the greatest variety of glacial landforms (moraines, fossil debris-covered glaciers and rock glaciers), but their age and formation process are poorly known. Here, we focus on the headwaters of the Garonne River, namely on the low-altitude Bacivèr Cirque (highest peaks at ~2600 m), with widespread erosive and depositional glacial and periglacial landforms. We reconstruct the pattern of deglaciation from geomorphological observations and a 17-sample dataset of 10Be Cosmic-Ray Exposure (CRE) ages. Ice thickness in the Bacivèr Cirque must have reached ~200 m during the maximum ice extent of the last glacial cycle, when it flowed down towards the Garonne paleoglacier. However, by ~15 ka, during the Bølling-Allerød (B-A) Interstadial, the mouth of the cirque was deglaciated as the tributary glacier shrank and disconnected from the Garonne paleoglacier. Glacial retreat was rapid, and the whole cirque was likely to have been deglaciated in only a few centuries, while paraglacial processes accelerated, leading to the transformation of debris-free glaciers into debris-covered and rock glaciers in their final stages. Climate conditions prevailing at the transition between the B-A and the Younger Dryas (YD) favored glacial growth and the likely development of small moraines within the slopes of the cirque walls by ~12.9 ka, but the dating uncertainties make it impossible to state whether these moraines formed during the B-A or the YD. The melting of these glaciers favored paraglacial dynamics, which promoted the development of rock glaciers as well as debris-covered glaciers. These remained active throughout the Early Holocene until at least ~7 ka. Since then, the landscape of the Bacivèr Cirque has seen a period of relative stability. A similar chronological sequence of deglaciation has been also detected in other cirques of the Pyrenees below 3000 m. As in other mid-latitude mountain regions, the B-A triggered the complete deglaciation of the Garonne paleoglacier and promoted the development of the wide variety of glacial and periglacial landforms existing in the Bacivèr cirque.