ICG2022-8

Ground-surface thermal (GST) measurements in high mountains are frequently used to examine the near-surface energy exchange fluxes. GST records are also used to determine if microclimatic conditions at the rock glacier surface are suitable for permafrost preservation. GST is commonly measured with miniature temperature data loggers. A decade record (2011-2021) of GST and air temperature from twenty sites in the Southern Carpathians are analyzed in this work. The controlling role of meteorological, topographical and subsurface characteristics on the GST regime was carefully examined. Snow cover and air temperature have the primary role in controlling the inter-annual differences and evolution of GST. At all the sites, the occurrence of permafrost was limited to areas characterized by coarse openwork debris, the reduced income of solar radiation and high altitudes (above 2000 m). The high porosity of coarse debris enhances an intense cooling of the ground due to efficient ventilation effects. In the case of active rock glaciers, the very low ground surface temperature regimes result from the combined effect of the ice-rich frozen debris, snow characteristics and ground airflow (convection and advection) within the loose debris. The permafrost distribution is patchy because the controlling topo-climatic factors reveal a small-scale variability. Thus, high variations of the thermal conditions at the surface of the investigated rock glaciers may occur over relatively small distances (e.g., a few hundred meters). Today the climatic conditions in the Romanian Carpathians permit only the preservation of thin frozen layers at sites where local topo-climatic factors and surface characteristics are favourable.

How to cite: Onaca, A., Ardelean, F., Sîrbu, F., and Berzescu, O.: Factors influencing the ground thermal regime of rock glaciers in the marginal periglacial environments of Southern Carpathians, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-556, https://doi.org/10.5194/icg2022-556, 2022.

Following the Last Glacial Maximum, icelandic hillslopes experienced a paraglacial crisis, which occurred between 15-10 ka BP. In the North, West and East parts of Iceland, in the high plateaus and slopes developed in the Tertiary basaltic formations, two types of paraglacial denudation features, deep-seated gravitational slope deformation (DSGSD) and rock-slope failure (RSF) deposits, are numerous.

An inventory and several maps of DSGSD and RSF are proposed at the scale of those three icelandic regions of Iceland. The mapping was made by combining aerial photographs, satellite images and field prospections. The DSGSD is characterized by typical ridge-top grabens, scarps and antiscarps associated with upslope and downslope dipping fractures along bulged upper slopes. The RSF could be identified by defining the crown and deposits. Both features could be analyzed by using direct observations and NDVI index from satellite images.

An approach of the timing of the DSGSD and rock-slope failures settlement is also proposed in this contribution by using field investigations (geomorphological stacking, tephrochronology, radiocarbon dating of wood remains in depression on RSL deposits, and age-depth models). The genetic links between DSGSD and landslides, the effects of these paraglacial denudation dynamics on the evolution of landforms (cirques, valleys) are discussed. Furthermore, the erosion rates involved by such paraglacial crises (volumes of landslide deposits) are compared with erosion rates involved other processes on icelandic slopes during the Holocene.

Finally, this paraglacial denudation crisis, illustrated by DSGSD and RSF, appears as the main sequence of icelandic landscape evolution since the last glaciation.

How to cite: Mercier, D., Portier, E., Decaulne, A., and Cossart, E.: Deep-seated gravitational slope deformation and rock-slope failures deposits in Iceland: inventory, dating and role in landscape evolution, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-165, https://doi.org/10.5194/icg2022-165, 2022.

Boulder-dominated landforms of periglacial, paraglacial and related origin constitute a valuable, but often unexplored source of palaeoclimatic and morphodynamic information. The timing of landform development initiation and its subsequent stabilization can be linked to past climatic conditions offering the potential to reconstruct cold climatic periods. In this study, Schmidt-hammer exposure-age dating (SHD) was applied to a variety of boulder-dominated landforms (e.g., sorted stripes and polygons, blockfield, paraglacial alluvial fan, rock-slope failure) in two different areas South Norway, Breheimen and Rondane. On the basis of old and young control points a regional SHD calibration curve was established and successively utilised for the calculation of surface exposure ages for individual landforms. The chronological investigation of development and stabilization of the respective landforms permitted an assessment of Holocene climate variability in different areas of South Norway and its impact on overall landform evolution. The obtained SHD ages range between 11.44 ± 1.22 to 3.45 ± 0.70 ka showing their relict character. There appear to be differences in the timing of stabilization of comparable landforms between the eastern and western part of South Norway within ca. 100 km. For instance, sorted ground structures show particular age differences and stabilized around 3 ka earlier in the eastern study area compared to the west. The sorted polygon ages in the west of 6.55 ± 0.68 and 4.76 ± 0.63 ka point to a stabilization around the Holocene Thermal Maximum (HTM; ~8.0–5.0 ka). In contrast, SHD ages from blockfields in both areas show rather young and comparable ages within the mid-Holocene, compared to former studies. Our obtained surface exposure ages from boulder-dominated landforms in two areas of South Norway give important insights into the local palaeoclimatic variability during the Holocene.

How to cite: Marr, P., Winkler, S., and Löffler, J.: Palaeoclimatic and morphodynamic implications from boulder dominated peri- and paraglacial landforms in two areas of South Norway, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-224, https://doi.org/10.5194/icg2022-224, 2022.

Our study looks at how to use the landform called “molard” as a marker of permafrost degradation in arctic, sub-arctic and mountain environments. Molards in permafrost terrains are mound of loose debris that derive from the degradation of blocks of ice-rich sediments mobilised by a landslide. Such molards cannot form without ground ice, which cements the source material, allowing it to behave like solid during transport. Once the ground ice has thawed, its cementing action is lost, inducing collapse of the material into molards. We reconstruct the permafrost, geological, geographical settings of more than 50 landslides characterised by molards, compiling data available in the literature. We apply quantitative terrain analysis using high-resolution DEMs to describe, quantify and compare their topographic characteristics, morphometry, dynamics, and molards distribution and density. Our results show that landslides with molards can occur in terrains characterised by various permafrost distribution, from continuous to isolated. These landslides show a variety of morphological and morphometric characteristics, source materials often composed of loose debris or rheologically weak bedrock, and their molard distribution reflects the dynamics of the landslide. In this study, we show that molards are an indicator landform of permafrost degradation under different permafrost, geomorphological and geological conditions, and that they can be used to decipher landslide dynamics in cold environments.

Acknowledgements: This study is funded by the Agence Nationale de la Recherche in the framework of the project ANR-19-CE01-0010 PERMOLARDS

How to cite: Morino, C., Conway, S., Deline, P., Magnin, F., Noblet, A., Svennevig, K., Lucas, A., Strom, A., Dunning, S., and Hermanns, R.: Molards, a new geomorphological tool for the identification of permafrost degradation in periglacial terrains around the globe, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-323, https://doi.org/10.5194/icg2022-323, 2022.

Glaciers and frozen-debris landforms have coexisted and episodically or continuously interacted throughout the Holocene at elevations where the climate conditions are cold enough for permafrost to occur. In the European Alps, the Little Ice Age (LIA) characterized the apogee of the last interaction phase. In areas of consecutive post-LIA glacier shrinkage, the geomorphological dominant conditioning of the ongoing paraglacial phase may have transited from glacial to periglacial and later even shifted to post-periglacial. Such transitions can be observed through the morphodynamics of glacitectonized frozen landforms (GFL), which are permafrost-related pre-existing frozen masses of debris deformed (tectonized) by the pressure exerted by an interacting glacier.

This contribution aims at evidencing the processes driving the ongoing morphodynamical evolution of two actively back-creeping GFL and a debris-covered glacier within the LIA forefield of the Challand and Epée glaciers on the basis of long-term time series of ground surface temperature, in-situ geodetic and geophysical measurements. Our observations for the last two decades (1997-2021), which have been the warmest since LIA, reveal a resistivity decrease in the permafrost body of the two GFL and a surface subsidence of a few centimetres per year up to locally a few decimetres per year. The former indicate a liquid water-to-ice content ratio increase within the permafrost body and the latter a ground ice melt at the permafrost table, both processes having taken place heterogeneously at the scale of the two GFL. These observations can be interpreted as the system is entering post-periglacial conditioning. In comparison, the still widespread debris-covered tongue of the Epée glacier, almost immobile and disconnected from the glacier active part, suffers a melt-induced subsidence of about 50 centimetres per year, indicating the insufficiency of the debris cover thickness to insure a long-term preservation of the ice under current climate conditions.

This study enhances the importance of decadal-scale and multi-disciplinary approach in understanding driving processes contributing to surface elevation changes due to ice melt or thawing frozen ground in permafrost-prone alpine LIA glacier forefields and to the dynamics of associated GFL.

How to cite: Wee, J. and Delaloye, R.: Insights on the morphodynamical evolution of an alpine Little Ice Age glacier forefield (Ritord, western Swiss Alps), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-572, https://doi.org/10.5194/icg2022-572, 2022.

Surface fluvial systems are very scarce in Antarctica and they are located in ice-free areas linked to deglaciation processes. In areas with recent deglaciation, the fluvial network development is connected with glacial retreat as well as other factors such as climatic conditions (precipitation distribution and amount; temperature and wind speed, among others). Ice and snow accumulation and thaw are closely controlled by temperature and reinforced by changes in wind speed and direction as well as direct rainfall on snow masses. As a result of local climatic conditions (high rainfall rates and exposition to winds), a considerable number of fluvial streams have developed in recent times on Byers Peninsula, due to the presence of more water to form channels. The typical Byers Peninsula stream system shows three parts: (1) upper reach with shallow slopes, diffuse drainage pattern due to high rates of water coming from the melting of ice and snow patches, low lying deep lakes and open braided channels; (2) gentle canyons in some cases covered by snow where water flows in snow/ice tunnels and (3) open channels where streams flow in a braiding way, controlled by several raised beaches that sometimes force the water into straight incised channels. We studied the relation between channel size and watershed area, size of fans and deltas and other morphological variables. Now and again, instantaneous events and catastrophic changes occur due to the collapse of ice-dams. As a result of such processes, new fans, small hummocky structures and stream channels take on a new morphology. Sometimes the landscape evolution does not explain the formation of stream channels and they remain in a misfit state. We determined the stream morphology (channel width, depth, wet section, longitudinal slope, basin area) in the following main groups of fluvial basins: streams draining to the South Beaches, to the North Beaches (President Beaches) and to the western coast (Robbery Beaches). Preliminary results show differences in streams morphology and the state of evolution among the three mentioned drainage groups which we think are probably due to differences in the deglaciation process. In addition, we also have noted differences among streams in the same drainage group that we interpret as linked to the speed and acceleration/stabilization of the deglaciation process.

This research was funded by the Spanish R&D National Plan RTI2018-098099-B-I00.

How to cite: Ortega-Becerril, J. A., Schmid, T., Carcavilla, L., and López-Martínez, J.: Fluvial stream dynamics and morphology on Byers Peninsula (Livingston Island, Antarctic Peninsula region): a model of landscape evolution in deglaciated areas, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-179, https://doi.org/10.5194/icg2022-179, 2022.

Mountain permafrost and rock glaciers have been intensely investigated in Southern Carpathians highest ranges in the last 15 years using thermal, geophysical and remote sensing methods. However, a complete estimation of permafrost area has not been done so far. Thus, using statistical modeling we intend to offer an image of potential permafrost distribution in Southern Carpathians ranges of Făgăraș, Iezer, Parâng, Retezat, Godeanu and Țarcu. Model 1 is based on machine learning algorithms and model 2 is based on Maxent model. Both models use bottom temperature of snow (BTS) data as independent variable and land cover, altitude, slope curvature, solar radiation and snow probability as independent variables. Land cover is considered the key variable as the field methods indicated that permafrost can only be present in the talus deposits that produce negative thermal anomalies in the underground. Results indicated an area of about 45-60 km² of potential permafrost distribution depending on the BTS threshold used for permafrost presence (-3°C, -2.5°C and -2°C). This represent about 0.01% from a total surface of about 4334 km² of the six ranges used in this analysis being a typical sporadic mountain permafrost in a marginal periglacial environment.

How to cite: Popescu, R., Filhol, S., Etzelmüller, B., Șandric, I., Pleșoianu, A., Vîrghileanu, M., Săvulescu, I., Vasile, M., Cruceru, N., Vespremeanu-Stroe, A., Westermann, S., Sîrbu, F., Onaca, A., Mihai, B., and Nedelea, A.: Permafrost distribution in the Southern Carpathians, Romania, derived from statistical modeling, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-655, https://doi.org/10.5194/icg2022-655, 2022.

The importance of frost weathering processes has long been discussed in the context of cold-climate landscape evolution. The 9 % volumetric expansion of in situ water when it freezes to ice was initially held responsible for generating the stresses that create and widen cracks in rocks. This theory has since been challenged by the theory of ice segregation in rocks, in which the growth of ice lenses is supplied by additional water that is drawn to the freezing front.  Numerical modelling and laboratory experiments suggest that segregated ice growth can generate enough stress to cause rock damage and is most intense between approximately -8 and -3 ℃ (the precise range depends on rock properties), in the so-called frost cracking window (FCW). The two theories of weathering have different implications for landscape evolution: (1) if in situ volumetric expansion is more important, most frost weathering should occur close to the freezing point, (2) if ice lensing is more important, most frost weathering should occur in the FCW. For the latter theory, several frost weathering indices have been developed based on such factors as the time spent vulnerable to cracking within the FCW, the magnitudes of ground temperature gradients that induce water transport, and other factors that affect water availability.

            In this study, we model ground temperature using the ground heat flux model CryoGrid 2D (Myhra et al., 2017) and apply the one-dimensional frost weathering index proposed by Rempel et al. (2016), where frost weathering potential is assumed to be correlated with porosity changes that accompany gradients in water flux. Here, we adjust the frost weathering index so that frost weathering potential is modeled in two dimensions. Our results predict spatial and temporal patterns of frost weathering in rock walls that can be tested in the field.

References

Myhra, K. S., Westermann, S., & Etzelmüller, B. (2017). Modelled distribution and temporal evolution of permafrost in steep rock walls along a latitudinal transect in Norway by CryoGrid 2D. Permafrost and Periglacial Processes, 28(1), 172-182. doi: 10.1002/ppp.1884.

Rempel, A. W., Marshall, J. A., & Roering, J. J. (2016). Modeling relative frost weathering rates at geomorphic scales. Earth and Planetary Science Letters, 453, 87-95. doi:10.1016/j.epsl.2016.08.019

How to cite: Czekirda, J., Etzelmüller, B., Rempel, A. W., and Westermann, S.: 2D-frost weathering indices for rock walls, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-90, https://doi.org/10.5194/icg2022-90, 2022.

Current climate change causes an increasing retreat of mountain permafrost. This retreat presents safety hazards due to more frequent slope instabilities. Thus assessing the state and evolution of permafrost is crucial. Unfortunately, mapping permafrost extent and retreat is not as simple as for other cryospheric landforms because permafrost is not directly detectable by remote sensing. However, in some mountain landslides, one can observe remnants of formerly ice-cemented blocks that degrade into cones of loose debris. These so-called molards imply the presence of an area of discontinuous permafrost at the level of the detachment zone.

To understand the processes that form molards we studied the degradation of the initial ice-cemented blocks by physical modeling. In nature, the height of these initial blocks ranges from 50 cm to up to 15 meters. For our experiments, it was, therefore, necessary to downscale the initial block to a more manageable cube size of 30 cm. These blocks are left to degrade under a controlled lab environment while being observed by a timelapse photogrammetric system as well as temperature and humidity sensors. The current experiments are investigating the effect of different sediment compositions, shape- and slope parameters on the decay and shape of the resulting molards. We find that especially the content of very fine sediment has a strong impact on the decay of the initial block due to its strong cohesion.

These initial results will be used to scale the experiment to the maximum size feasible in the lab: a 70 cm cube with a weight of up to 700 kg. The final goal is to create a numerical model based on the experimental findings, making it possible to distinguish molards from other similar landforms, such as hummocks or hummocky moraines. This knowledge can be used in the long term to identify and study these molards via remote sensing over a much larger area.

How to cite: Beck, C., Font, M., Conway, S., Philippe, M., and Lagniel, E.: Molards as proxies of permafrost degradation: investigating physical downscaled models, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-258, https://doi.org/10.5194/icg2022-258, 2022.

Sand-sized (0.5–1.0 mm) grains of mechanically-crushed vein quartz were subjected to the frost action under controlled, laboratory conditions. Defined temperature changes from -5˚C up to +10˚C provide cyclic freeze-thaw (FT) process, and thus simulate periglacial conditions. A total of 1000 FT cycles were simulated under low (213 mg/l) and high (1954 mg/l) water-mineralization conditions (LMW, HMW, respectively). Microtextural analysis of grain surfaces was undertaken using SEM (scanning electron microscope) before experimental run (0 FT cycles, i.e. reference sample) and after 50, 100, 300, 700 and 1000 FT cycles. Each time twenty randomly selected grains from each sample were analysed at low (~100-150x) and high (~1000x) magnification. The frequency of occurrence of individual microtextures on grains from a given sample was estimated, and frost-induced imprints were counted on each grain. The degree of surface coverage with a precipitated crust was determined qualitatively (low/high) and its elemental composition was determined by EDX (Energy-dispersive X-ray spectroscopy).

The results of this experimental simulation indicate that four mechanical microtextures can be considered as diagnostic ones for the frost weathering process. These are: small- and large-sized conchoidal fractures (cf, CF, respectively) along with small- and large-sized breakage blocks (bb, BB, respectively). Two predominant outcomes in the course of micro-scale frost weathering have been identified: a) a physical aspect of the process evidenced by numerous cf, CF, bb, BB microtextures during first 300 FT cycles; followed by b) a chemical aspect resulting in the precipitation of surficial crusts and obliteration of grain microrelief. The complexity of frost-originated microtextures and their location on grain surfaces reflect three stages in the evolution of frost-induced microrelief: 1 – initial, development of CF, 2 – progress, development of cf, and 3 – advanced, dominated by bb and BB growth; summarized as: crack → CF → cf → bb → BB. This evolution may, however, be influenced and interrupted by the grain refreshing process, when cracking and detachment during the formation of CF reveal the fragments of fresh, unweathered surface of grain. This frost-induced refreshment causes the grain to lack some / most of the mechanical frost-originated microtextures. It may occur many times at each stage (1, 2, 3) of the weathering process and the cycle of development of frost-originated microrelief (crack → CF → cf → bb → BB) is thus repeated. The term ‘renewal of frost weathering’ has been introduced here for this event. The obtained results indicate that microtextural characteristics of frost-weathered grains depends largely on the mineralization of water involved in the process. It seems that frost weathering of the quartz grains enveloped with HMW is more effective than of these poured with LMW.

Acknowledgements. The project is financially supported by the National Science Centre Poland. Grant No. 2019/33/N/ST10/00021.

How to cite: Górska, M. E. and Woronko, B.: Multi-stage evolution of frost-induced microtextures on the surface of quartz grains – experimental study, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-303, https://doi.org/10.5194/icg2022-303, 2022.

Permafrost repeatedly occurred across central Europe during cold periods of the Pleistocene, as evidenced by a number of past periglacial features that are present in both highland and lowland areas. Many of those periglacial features, such as frost wedges and other kinds of patterned ground, cryoturbations, or pingo scars, have been widely utilized to estimate past air temperature conditions. However, the reconstructions have only relied on temperature thresholds of active periglacial features that are now mostly found in high-latitude periglacial environments. Such empirical interpretations have thus often been considered problematic and of limited validity.

Nevertheless, periglacial features mostly form as a result of recurrent freeze-thaw processes that act within the active layer over permafrost, the base of which is commonly sharply defined and limits the subsurface extent of periglacial features. The active-layer thickness (~depth of maximum annual thaw) usually attains several decimetres to metres, which mainly depends on summer and annual temperature conditions. Since the thickness of palaeo-active layer can be determined based on past periglacial features, it can thus also be used to estimate the temperature conditions that gave rise to an active layer of a given thickness.

Here, we present a novel model we have devised that uses the above principles. The palaeo-mean annual air temperature modelled so far at two lowland sites in the Czech Republic where Last Glacial cryoturbations occur ranged between −7.0±1.9 °C  and −3.2±1.5 °C, and its corresponding decline compared to the 1981–2010 period was between −16.0 °C and −11.3 °C, which agrees well with reconstructions utilizing various palaeo-archives. These initial results are promising and suggest that the model could become a useful tool for reconstructing Quaternary palaeo-air temperatures across vast areas of mid-latitudes and low latitudes where relict periglacial features frequently occur, but their full potential remains to be exploited. Additionally, it could help us refine existing and/or provide new insights into past periglacial environments that cannot be unveiled by other abiotic or biotic indicators.

The research is supported by the Czech Science Foundation, project no. 21-23196S.

How to cite: Uxa, T. and Křížek, M.: Derivation of palaeo-air temperature conditions from past periglacial features, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-542, https://doi.org/10.5194/icg2022-542, 2022.

Aeolian dune field pattern could provide a very detailed image of the influence of environmental controlling factors (wind regime, topography, sediment supply and others) to its development. Moravian Sahara dune field located in Southern Moravia, Czechia, and thus far away from the European Sand Belt (i.e. the area of major aeolian accumulations in Europe), represent a unique archive reflecting the effects of these variables. Even despite its remoteness from the Fennoscandian Ice Sheet during the Last Glacial Maximum, the permafrost occurred in Southern Moravia, and thus periglacial processes operated here. Different approaches including LiDAR DTM analysis, ground-penetration radar (GPR), and near-surface wind modelling were applied to investigate the role of the controlling factors. Two groups of differently oriented periglacial-related dunes (ENE-WSW and N-S) have been distinguished via the DTMs, suggesting a significant twist in atmospheric circulation connected with the retreat of the Fennoscandian Ice Sheet after the Last Glacial Maximum. Beside that, a strong influence of the local topography to the modification of the wind flow and the possible sediment sources were distinguished and described. Furthermore, confrontation of the reconstructed palaeowind directions with the modelled atmospheric circulation during the Weichselian and the OSL ages of aeolian sediments enabled the temporal assignment of the Moravian Sahara dune field development to the Late Pleniglacial and Late Glacial periods. Thus, our results show their applicability to the very detailed study of the influence of environmental conditions on the development of the cold-climate aeolian dune fields.

How to cite: Holuša, J., Nývlt, D., Woronko, B., Kuda, F., Moska, P., Matějka, M., and Stuchlík, R.: Late Weichselian history of the Moravian Sahara cold-climate dune field, Lower Moravian Basin, Czechia, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-105, https://doi.org/10.5194/icg2022-105, 2022.

The timing of past glacier fluctuations is poorly constrained in Corsica island (Western Mediterranean Sea). Although several glacial landforms and deposits were described, there are no absolute glacial chronology. We will present 19 new 10Be cosmic-ray exposure ages (CRE) of boulders collected from 4 moraines located in the area of the Bastani Lake (Monte Renoso, Northern Corsica). For the first time on a Mediterranean island, mountain glacier fluctuations are documented from moraine CRE for the Lateglacial Period. Two main glacier advances since the Last Glacial Maximum are identified. 12 boulders of three moraines dated between 14.98 ± 0.89 ka BP and 18.88 ± 1.04 ka BP reveal a glacier extent during the Oldest Dryas (Heinrich Stadial 1 - HS1). 5 boulders of one moraine dated between 12.13 ± 0.69 ka BP and 13.93 ± 0.79 ka BP are attributed to the Late Glacial–Younger Dryas transition. Results and associated past Equilibrium Line Altitude will be compared with those in the Mediterranean mountain ranges. Implications for regional climatic conditions will be discussed.

How to cite: Chenet, M., Brunstein, D., Jomelli, V., and Team, A.: First glacial chronology in Corsica (Western Mediterranean Sea) based on 10Be moraine dating: evidence of two glacier extents since the Last Glacial Maximum, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-131, https://doi.org/10.5194/icg2022-131, 2022.

During the 20^th century, the last glaciation in the Massif Central, France, was documented by several geomorphologists based on intensive field investigations. Seven paleoglaciers were identified, ranging from cirque glaciers in the Velay (4 km²) to coalescent ice caps (3500 km²) covering the Cantal, Cézallier and Monts Dore mountains. The associated glacial chronology relied mainly on morphostratigraphic observations and indirect age determination, such as radiocarbon ages from organic sediments in freshly deglaciated landscapes. Our study aims to improve this incomplete glacial chronology in order to reconstruct the paleoclimatic conditions that controlled these glaciations. We focused on the Cantal Mounts (45.0°N, 2.7°E) and Aubrac Mounts (44.6°N, 3.0°E) in the western Massif Central. Glacial landform assemblages and associated morphostratigraphy were re-investigated in the field and updated by new observations, e.g. the identification of end moraines. Three glacial stadials were recognized: the Local Last Glacier Maximum (LLGM) and two glacier re-advances. A final cirque glaciation was identified in the Cantal. We obtained an original set of exposure ages from erratic boulders and depth profiles in till at key sites using in situ produced Terrestrial Cosmogenic Nuclides ¹⁰Be, ²⁶Al and ³⁶Cl. Our results show comparable glacial chronologies for the Cantal ice cap and the Aubrac plateau icefield suggesting that the majority of glacial landforms and sediments were deposited during the global Last Glacial Maximum (LGM; 26.5 to 19.5 ka) and the Last Glacial-to-Interglacial Transition (LGIT; 19.5 to 11.7 ka). Advances and retreats of these two paleoglaciers were synchronous with regional climatic events reported from independant paleoclimatic proxies, especially the Heinrich Stadial 2 and the Heinrich Stadial 1. We combined two glacier modelling procedures, the theoretical glacier surface profiles and the Positive Degree-Day method, to constrain the paleoclimatic conditions (i.e. paleotemperatures and paleoprecipitations) that controlled these glacial fluctuations. The results showed changes between past and current climatic gradients with a probable enhancement of southerly moisture advection from the Mediterranean during the Heinrich Stadial 2 and drier conditions during the Heinrich Stadial 1.

How to cite: Ancrenaz, A., Defive, E., Pochat, S., Rinterknecht, V., Rodrìguez-Rodrìguez, L., Poiraud, A., Schimmelpfennig, I., Braucher, R., Jomelli, V., Bourgeois, O., and Steiger, J.: Reconstructions of the last deglaciation in the Cantal and the Aubrac mountains (Massif Central, France) and paleoclimatic implications, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-315, https://doi.org/10.5194/icg2022-315, 2022.

Several mountains in Turkey were glaciated during the Late Pleistocene. One of them, Mt. Aladağ, is located in the central Taurus Range and covers an area of 800 km². The elevation changes from 400 to 3771 m asl, making the mountain one of the most profound karst systems in the world. It is limited by several outwash fans, cut and offset by the left-lateral Ecemiş Fault Zone on the west, Zamantı River on the east, and Mt. Karanfil on the south. Two major local ice caps >3000 m asl, on Yedigöller and Körmenlik Plateaux, occupied the summits of Mt. Aladağ in the past. Although several glacier tongues derived from these ice caps and deposited moraines and outwash fans, today, only a few debris-covered glaciers and rock glaciers are left. We used the cosmogenic ³⁶Cl surface exposure dating method on limestone bedrock, moraine and outwash fan boulder samples to constrain the timing of paleoglaciations. A total of 121 samples indicate several episodes of deglaciation during the last glacial cycle. The oldest moraines (~47 and ~38 ka old) are found in the W-NW of Mt. Aladağ in two adjacent valleys. An outwash fan (~78 ka) at the exit of the northern valley also indicates the existence of earlier glacial conditions, also confirmed by previous outwash fan ages obtained from the SW of the mountain. The highest peaks (>3200 m) became ice-free by ~55 ka, but two ice caps remained active till the onset of the Holocene. Interestingly, the Last Glacial Maximum (LGM; ~21 ka) moraines are rare and only preserved at high altitudes. On the other hand, the longest paleoglacier (>15 km) of Mt. Aladağ, on the eastern side, rapidly retreated from ~15 ka to ~12.5 ka, indicating Late Glacial to Younger Dryas deglaciation. Additionally, Early Holocene moraines are found in eastern and western valleys abundantly.

On the other hand, Mt Karanfil (3059 m asl), a small mountain 20 km south of Mt. Aladağ, contains four well-preserved terminal and lateral moraine complexes, each originating from one to three cirque areas from the mountain’s N-NW face. The mean ages of moraines range from ~17 ka to ~19 ka, indicating mostly an LGM deglaciation. One sample from a relict rock glacier in a cirque floor was dated to ~10 ka, testifying to the development of permafrost conditions on the onset of Holocene. We also used the Parallel Ice Sheet Model (PISM) to reconstruct the glaciers and climate during the LGM on Mt. Karanfil. We ran 21 paleoclimate simulations as a function of present temperature and precipitation to reach the steady‐state glacier extents and compared the results with the modelled glacial areas and the field‐observed ice extents. The best‐fit setups imply that Mt. Karanfil’s LGM climate was 8.3 ± 0.5 ^oC colder than today if the precipitation levels were the same as today. More humid (20% wetter) or arid (20% drier) conditions produce paleotemperatures 6.9 ± 0.4 ^oC or 10.4 ± 0.6 ^oC lower than today, respectively. Financial support by TÜBİTAK 116Y155 and ANSTO (AP11366) projects are greatly acknowledged.

How to cite: Ciner, A., Sarıkaya, M. A., Köse, O., Candaş, A., Yıldırım, C., and Wilcken, K.: Cosmogenic 36Cl glacial chronology and ice-flow modelling (PISM) of Aladağ and Karanfil Mountains, Central Taurus Range, Turkey, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-39, https://doi.org/10.5194/icg2022-39, 2022.

Geomorphological vestiges in the mountains of NW Portugal testify a low altitude, sheltered, and precipitation-driven glaciation. These vestiges have already been characterised in several works, with emphasis on mapping and delimitation of the extent of glaciation, especially in the Serra do Gerês. In Serra da Peneda, the glacial reconstitution is not so comprehensive. Previous works have identified erosional and accumulation landforms, as well as various types of tills. However, the maximum extent of glaciation still raises some doubts and the spatial discontinuity of vestiges could suggest different episodes of glaciation. To detail the extent of the glaciation in the Serra da Peneda, an identification of glacial and periglacial landforms and deposits was performed, based on field surveys, aerial photography analysis, and LiDAR imagery processing and interpretation. Moreover, ¹⁰Be cosmogenic nuclide dating of moraine granite boulders exposure age was carried out in the Alto Vez valley, the area where the main glacial vestiges occur. Samples were collected from the uppermost erratic boulders of Senhora da Guia, at 1000 m asl., pointing to a Last Glaciation Maximum (LGM) age whereas the moraine boulders of the valley floor, at 900 m asl. indicate a Younger Dryas age. These are the first glacial dating results for this region and are in contrast to others previously published for exposure ages of glaciated surfaces in the Serra do Gerês, which raises the possibility that different Pleistocene glaciations may be represented in the mountains of NW Portugal. To reconstitute the history of glaciations in the region, similar dating in other moraines of the Peneda and Gerês mountains is in progress.

How to cite: Pereira, P., Binnie, S., Dunai, T., Henriques, R., and Pereira, D.: On the age and extent of the Serra da Peneda glaciation, NW Portugal, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-605, https://doi.org/10.5194/icg2022-605, 2022.

The valleys of the Maritime Alps (SW European Alps) host a variety of glacial sediments and landforms, and several well-defined moraine ridges have been ascribed to advances that occurred during the Last Glacial Maximum (LGM). Utilising these moraines to reconstruct paleoglacier 3D geometries and their associated Equilibrium Line Altitudes (ELAs) is an excellent method to estimate paleoclimatic parameters, especially if integrated into a solid geochronological framework. Previous studies have been focusing mostly on the catchments of the Gesso and the Stura rivers with other areas receiving less attention. Particularly, chronologically constrained reconstructions of relatively small LGM valley glaciers (in the order of 1-10 km²) are largely lacking, but due to their shorter response times can prove crucial for a better understanding of local and regional paleoclimatic patterns, such as the influence of the proximal Mediterranean Sea on moisture supply during the LGM.

Here, we present new insights into the dynamics of some LGM valley glaciers in the Maritime Alps from three different catchments. These catchments hosted glaciers of varying sizes, aspects, and elevation ranges and are located both on the Italian and French side of the mountain range. Chronological control is provided by 15 new ¹⁰Be surface exposure dates, for which samples were taken from boulders on lateral and frontal moraine ridges. Results show that glaciers remained at an advanced position up until around 19 ka. This indicates that climatic conditions, favourable for glacier growth, continued to prevail in the south-western Alps into the latter part of the LGM. Chronologies, reconstructed glacier geometries, and associated ELAs, are presented along with the implications of the findings for our understanding of the LGM paleoclimate.

How to cite: Rettig, L., Kamleitner, S., Ivy-Ochs, S., Monegato, G., Mozzi, P., Ribolini, A., Rea, B. R., Ashpitel, L., and Spagnolo, M.: New insights into the Last Glacial Maximum in the Maritime Alps from paleoglacier reconstructions and 10Be surface exposure dating, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-432, https://doi.org/10.5194/icg2022-432, 2022.

Subglacial landforms are key elements of reconstructing ice sheets dynamics and processes. Among less studied are transverse and elongated glaciogenic ridges (TEGRs) perpendicular to ice flow usually classified as Ribbed (Rogen) Moraines (Barchyn, 2016; Cline, 2015). Their shape is closely connected to low ice movement speed as distinct from drumlins and large scale lineations that were formed under condition of a higher ice movement velocity. Typically, they are straight, up to 30 m high, up 1000 m long and 150-300 m wide. Rajgród ridges, although similar to classic case, have unique features, both individual and related to their mutual position.

For the purposes of research XYZ LIDAR data with resolution of 4 points per sq meter was used to calculate high accuracy DEM, on the base of which hillshade model and topographic position index map were prepared. Initially all TEGRs were indicated and subsequently send to and evaluated independently by three researchers to determine their ridgelines and borders. For further steps only ridges with similar parameters within all researchers were examined and used for parameter calculation: (1) area, (2) length measured by ridge line, (3) height as a differential between highest and lowest elevation, (4) mean width calculated as ratio area to perimeter and (5) vertical sinuosity defined as the ratio of topographic length to length. All TEGRs were divided into five fields (clusters), similar in ridges number.

TEGRs located near Rajgród lie close to the former ice margin and have the highest vertical sinuosity and mean width. They are fragmented, with doughnut landforms visible on TEGRs surface, whereas TEGRs located in cluster proximal part are better preserved, have higher area and lower mean width then those in distal part. The cross-profile through all the fields shows a clear arrangement of morphological levels referring to the stages of ridges formation. First level is connected to initial stage when certain areas had undergone quicker ice movement. The second one is correlated to creation of ridges in ice crevasses. The third and last one is the sign of deglaciation and creation of doughnut features.

This study was carried out as part of the scientific project financed by the National Science Centre (NCN) in Poland, project no. 2018/31/B/ST10/00976.

References

Barchyn, T. E., Dowling, T. P. F., Stokes, C. R., & Hugenholtz, C. H. (2016). Subglacial bed form morphology controlled by ice speed and sediment thickness. Geophysical Research Letters, 43(14), 7572–7580. https://doi.org/10.1002/2016GL069558

Cline, M. D., Iverson, N. R., & Harding, C. (2015). Origin of washboard moraines of the Des Moines Lobe: Spatial analyses with LiDAR data. Geomorphology, 246, 570–578. https://doi.org/10.1016/j.geomorph.2015.07.021

How to cite: Chabowski, M., Weckwerth, P., Wysota, W., and Adamczyk, A.: Geomorphometry of cyclical semicentric and semicurvate till ridges in Rajgród (NE Poland) as a record of the last ice sheet dynamics, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-506, https://doi.org/10.5194/icg2022-506, 2022.

During the Pleistocene Glacial Cycles, low mountains of the NW Iberian Peninsula, such as Soajo (1417 m) and Gerês-Xurés (1525 m), were shaped by ice caps (Pérez-Alberti, 2022). The presence of ice bodies and related movements impacted NW Iberian climatology and landscape geomorphology, being the aim of several research and controversies. 

In the low-lying altitudes of the mountains in NW of Portugal and Galicia, some conditions favoured the accumulation of snow and the formation of glaciers. Firstly, their geographical position near the Atlantic, which brings cold-humid air masses due to the oceanic sub-polar fronts, and at the same time, their transversal shape as an orographic barrier (N-S) forcing the rapid rise of humid and cold air. Then, the shelter position of the valleys with dominant orientations NE, E and N with low solar radiation values.

The glaciation of the Soajo Mountain was not yet well understood. To decrease this gap was performed detailed fieldwork and desk studies interpretation to identify and map the glaciogenic landforms (e.g., moraine ridges, erratic blocks, polish surfaces, till, cirques, glacier tongues). Fieldwork was made using the API Survey to register the location, descriptions and dimensions of landforms identified in the field and laboratory. Geomorphological interpretations were supported by topographic LiDAR data (70 cm of resolution) and ortho-rectified imagery (max. of 25 cm of resolution).

Based on the published and the new data collected, this study presents a new geomorphological map of the existing glacial evidence for Soajo Mountain. In addition, it shows the three-dimensional modelling results regarding the maximum extent and the thickness of the palaeoglacier. 

To accomplish the palaeoglacier reconstruction was drawn the possible Maximum Extent of Glaciation (MEG), the Palaeoglacier Surface and the Glacial Flowline. Additionally, the GlaRe toolbox calculated ice thickness (Pellitero et al., 2016).

The palaeoglacier DEM result highlights a significant glacial activity despite the low altitude of the studied area. Considering the MEG, the area covered by ice was approximately 16 km2.

Four areas reveal the W-E asymmetry on ice distribution: the top Ice Field of Lamas de Vez with 181 m of ice thickness feeding by glacial overflow, the Southwestern sector of Ramiscal; the ‘U’ shaped Vez valley with 170 +/-10 m of ice thickness also powered by the Aveleira glacier; and the Eastern glacial sector, also fed by the Ice Field, favoured the glacial accumulation by valleys sheltered position showing a cascade glacier type with thin glacier tongues between 139 and 32 m of ice thickness. On the mountain's west slope, the isolated glacier tongue reveals a maximum ice thickness of 106 m.

References:

Pellitero, R., Rea, B. R., Spagnolo, M., Bakke, J., Ivy-Ochs, S., Frew, C. R., Hughes, P., Ribolini, A., Lukas, S., & Renssen, H. (2016). GlaRe, a GIS tool to reconstruct the 3D surface of palaeoglaciers. Computers and Geosciences, 94, 77–85.

Pérez-Alberti, A. (2022). The glaciers of the Peneda, Amarela, and Gerês-Xurés massifs. In Iberia, Land of Glaciers, Elsevier. 397-416.

How to cite: Figueira, E., Gomes, A., Pérez-Alberti, A., and Chaminé, H. I.: 3D modelling of the maximum ice extent and thickness of the palaeoglacier of Serra do Soajo, Northern Portugal, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-630, https://doi.org/10.5194/icg2022-630, 2022.

The Schmidt-hammer has been used in Geomorphology for the last decades. The effectiveness of the method has been proven by several authors, but some limitations also exists. In this work, this procedure has been tested in glacial and periglacial landforms in five different massifs in the province of León (northwestern Spain): Vizcodillo, Arcos del Agua, Muxivén, San Isidro and Peña Pieta. Tested landforms include moraines, rock glaciers, polished outcrops, talus slopes, blockfields and a debris avalanche. Quartzite has been widely used for this purpose, but granodiorite, shales and sandstones have also been tested. Results show that Schmidt-hammer data generally agree with geomorphological reconstructions. They also show strong correlation with cosmic-ray exposure ages where they exist. Rebound values are high, ranging from ≈70-72 in the oldest landforms (last glacial stage) to ≈77-80 in the most recent ones, with small differences within massifs.
In Vizcodillo, four glacial stages have been clearly differentiated since the last local glacial maximum. In Arcos del Agua, periglacial deposits show two different stages of rock glaciers generation and a progressively younger age for different talus slopes related to deglaciation. At both sites, the blockfields are younger than rock glaciers. In Muxivén, Schmidt-hammer data agree with the cosmic-ray exposure dating results, indicating that most of the postglacial deposits were generated due to rapid deglaciation during the Bølling-Allerød period. In San Isidro, the results show two possible stages for rock glaciers. In Peña Prieta, different glacial and periglacial deposits were tested, but poor results were obtained.
Relevant differences have been observed depending on the lithology. The mean coefficient of variation in the rebound values of the boulders was 3.1% in Arcos del Agua (quartzite), 3.5% in Vizcodillo (quartzite), 3.8% in Muxivén (quartzite), 4.7% in San Isidro (quartzite sandstones), but 9.9% in Peña Prieta (granodiorite). The differences between boulders of the same landform were also clearly greater in Peña Prieta than in the other massifs, with the quarzitic areas showing the most robust results. Although it has been used in previous works with good results, in this study granodiorite presented a significant dispersion in the rebound values of the boulders, due to the fact that its internal composition is coarse-grained and presents grains with different resistance. Shales could not be correctly tested because they offered great dispersion in the data. The results addressed the importance of selecting suitable and comparable areas on boulder surfaces for Schmidt-hammer impacts, with resistant and homogeneous lithology showing better results. Conversely, areas with high lithological heterogeneity or coarse-grained boulders may not to be suitable for the Schmidt-hammer method. Further surface exposure dating is needed to establish a calibration curve in this area.

How to cite: Santos-González, J., González-Gutiérrez, R. B., Gómez-Villar, A., Redondo-Vega, J. M., Peña-Pérez, S. A., Melón-Nava, A., and Pisabarro-Pérez, A.: The use of Schmidt-hammer for relative-age dating of glacial, periglacial and paraglacial deposits in NW Spain, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-59, https://doi.org/10.5194/icg2022-59, 2022.

The spatial and temporal patterns of Holocene glacial oscillations in most currently ice-free areas of Antarctica remains unknown. This work focuses on the recent deglaciation in the northern sector of the Fildes Peninsula, King George Island, northern Antarctic Peninsula. The ice cap covering ca. 90% of the island has receded since the last glacial maximum and exposed ca. 29 km² of ice-free land. We reconstruct its glacial history based on a dataset of 12 ³⁶Cl exposure ages obtained through Cosmic-Ray Exposure (CRE) dating of moraine boulders, polished surfaces and erratic boulders surrounding the peninsula’s northern plateau. Results reveal that the deglaciation of the northern Fildes Peninsula took place during the Holocene Thermal Maximum at 7-6 ka, when warm conditions promoted a massive glacial retreat. The present arrangement of ice-free areas was in place by 6 ka. Small cirque moraines suggest the subsequent occurrence of favourable climate conditions for glacial expansion fed by intense snow deflation at 4.6 and 1 ka at the foot of the northern plateau. The deglaciation pattern of the Fildes Peninsula resulted from the combined shrinkage of different ice masses, rather than of the long-term retreat of the King George Ice Cap. No evidence of glacier expansion during more recent cold periods (i.e. the Little Ice Age) was found. These results fit well with regional deglacial histories inferred from lacustrine sediments and raised beaches and complement the existing chronological framework to help better understand the peninsula’s Holocene geoecological dynamics.

How to cite: Oliva, M., Palacios, D., Fernández-Fernández, J. M., Fernandes, M., Schimmelpfennig, I., Vieira, G., Antoniades, D., Pérez-Alberti, A., and Garcia-Oteyza, J.: Neoglacial oscillations in the northern Fildes Peninsula, King George Island, Antarctica, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-428, https://doi.org/10.5194/icg2022-428, 2022.

The complex interactions between the redistribution of water mass in the ocean basins due to continental ice sheet growth and decay, and the attendant Glacio-Isostatic Adjustment (GIA) process play a major role in controlling Relative Sea-Level (RSL) variability since the Last Glacial Maximum (LGM). In near-field regions (e.g., areas covered by the major ice-sheet at the LGM), the rate of GIA uplift during deglaciation often exceeded the rate of RSL rise from an increase in ocean volume due to the melting of land-based ice.

Here, we assembled a database of new and previously published RSL collected along the coasts of the Ross Sea (Antarctica). The set of ¹⁴C radiocarbon dates was obtained from samples of Adelie penguin guano remains and shells found on raised beaches and collected during several Antarctic expeditions conducted in the framework of the Italian Programme of Antarctic Researches (PNRA). We further revisited about 300 radiocarbon dates available in literature following the standards of the latest International Geoscience Programme (IGCP) protocols on sea-level studies. All these dates were also recalibrated according to the latest calibration curve

We thus produce a new set of 65 RSL data points which have been classified in i) Sea Level Index Points (SLIP), when the relationship between the sample and the tidal level is clearly known (e.g., raised beaches), ii) marine and iii) terrestrial limiting points which indicate the upper and the lower threshold for the former sea-level position, respectively.

In order to reconstruct the RSL trend in the last thousands of years, a critical interpretation of the dated materials has been carried out. For example, data show that the penguin guano and remains from ornithogenic soil on top of beaches and on abrasion platforms significantly rejuvenated the age actual age of the beach ridges.

We finally applied on the new dataset a spatio-temporal empirical model to reconstruct magnitudes and rates of RSL change (with associated uncertainty) from SLIPs along the Ross Sea area. The model output shows a continuous RSL drop of about 25 m last ~7 ka BP. This drop was generally characterized by average rates comprised between ~2 to ~4 mm/y. An episodic increase of the RSL falling rates, up to ~6 mm/y was found at ~4 ka BP, likely related to a local increase of the GIA contribution

This study, based on a robust number of radiocarbon dated coastal deposits, will allow to better define the recent Antarctic ice-sheet fluctuation and to contribute in the tuning of the GIA models in this key sector of the World’s coastlines.

How to cite: Cerrone, C., Salvatore, M. C., Baroni, C., Hall, B., and Vacchi, M.: Spatio-temporal reconstruction of the post-glacial sea-level evolution in the Ross Sea, Antarctica, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-554, https://doi.org/10.5194/icg2022-554, 2022.

Tropical glaciers are among the fastest retreating in the world. The two largest tropical glaciers are located in South Perú. Quelcaya icecap (-13.92°, -70.80°, 5650 masl) sits at the Eastern wetter fringe of the Andean Plateau, near the Amazon basin, from which it receives precipitation. Nevado Coropuna (-15.54°, -72.64°, 6377 masl), sits on a volcanic building at the arid, Western part of the Andean Plateau, under the influence of the Humboldt ocean current.

MOTICE is an ongoing project that will measure the retreat of Nevado Coropuna and Quelcaya since the 1950’s. Glacier reach, mass balance and thickness will be measured using remote sensing, GPS, UAV and GPR, whereas deglaciated areas will be studied in terms of their geomorphology. Alongside climate data, the glaciological and geomorphological information will feed a glacier model that will try to replicate the retreat that has happened in the last 70 years. Once tuned, the model will be forced with different future RPC scenarios in order to know the future retreat of the two aforementioned icecaps. In this contribution we present preliminary results on the 1950’s-present deglaciation landsystems and discuss their potential feed into glacier modelling.

In the case of Nevado Coropuna, results show a distinctive landform creation pattern between the North and South face, which we expect be linked to a differential retreat pattern. Northern proglacial areas predominantly feature a push-moraine/fluting landsystem that speaks of fast glacier motion and dynamic retreat, which is confirmed by the highest retreat rates in the whole icefield. Conversely, southern glacial landsystem show the typical setting of a stagnant glacier front, with debris covered glaciers, rock glaciers and a very limited frontal retreat. Recent rock glacier formation in high mountain environments has already been described in the Himalayas and might be a beneficial process for the storage of frozen water resources, as rock glaciers are more resilient to melt than glaciers.

Deglaciation landforms in Quelcaya evidence a quick retreat pattern, which left frontal and lateral moraines, some of them currently enclosing proglacial lakes in the main valleys and series of push moraines in less enclosed slopes. Recent deglaciation in the SW and NE tips of the icefield has reached the plateau on which it sits. Deglaciated areas on the plateau only show lightly scoured bedrock surfaces, hence evidencing cold-based, motionless ice.

Overall, Quelcaya is retreating at a faster pace than Nevado Coropuna, mainly because its lower elevation, which is expected to be fully placed within the ablation zone before 2050. It is expected that the described glacial geomorphology will help our glacier model in two ways: 1. tune some parameters in it, such as ice velocity and 2. provide temporal constraints (mainly from moraines) to the deglaciation process between the 1950’s and the present time.   

How to cite: Pellitero, R., Fernández-Fernández, A., Atkinson, A., Del Río, L. M., Ely, J., Gómez, R. J., Navarro, Á., Pasapera, J., Ribolini, A., Santillán, N., Úbeda, J., and Valcárcel, M.: Geomorphological constraints for tropical glacier retreat description and modelling: the MOTICE project in Nevado Coropuna and Quelcaya icecaps (Perú)., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-157, https://doi.org/10.5194/icg2022-157, 2022.

Climate reconstructions from the Third Pole show that climate change is not uniform, but tends to exhibit a consistent pattern with changes at the regional scale over the Himalayan axis than elsewhere. To find out the answers related to the questions about the past climate in the Changme Khangpu Basin (CKB), an important region of Eastern Himalayas, the palaeoclimate research has been carried out using the proxy of glacier dynamicity. CKB covering an area of 767.8 km² and climatically this part mainly controlled by the Indian Summer Monsoon (ISM), limited penetration of Western Disturbances and North-East Monsoon. To reach the objective, the study has opted for geomorphic feature analysis, sedimentological analysis, and associated with geochronological methods using the Accelerator Mass Spectrometry ¹⁴C dating and Schmidt Hammer rebound value dating methods to place the glacier variability and associated climate changes over time. In addition, glacier geomorphology has been used to reconstruct the equilibrium line altitude shifts and associated temperature departures. The three valleys such as Changme Khangpu (CK), Khong Kyong Kangse (KKK) and Katao have shown consistency in glacier advances and climatic shifts in different time periods. It has been estimated that the CK valley Phase-II glacier advance was initiated by the peak in ISM and enhanced by the transition climatic phase between MIS 3 (i.e. prior to 32 ka calBP) and MIS 2. The KKK Phase-I glacier advance was related to the CK Phase-II advance. In addition, the post-glacial (between 14.29 to 3.5 ka calBP) relatable climatic phases in the CK valley and Katao valley also have been identified.

Keywords: Changme Khangpu Basin; Eastern Himalayas; Palaeoclimate; Glaciers, ¹⁴C AMS dating; Schmidt Hammer rebound value.

How to cite: Debnath, M., Sharma, M. C., Syiemlieh, H. J., and Chowdhury, A.: Glaciers and Palaeoclimatic Reconstructions in the Changme Khangpu Basin, Eastern Himalayas, INDIA, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-438, https://doi.org/10.5194/icg2022-438, 2022.

The Sikkim Himalaya, similar to other mountain regions, has lost considerable ice cover over the years owing to the changing climatic factors leading to enlargement of glacier-fed lakes, and thus posing a potential threat to downstream communities in the mountain and Tarai (foothills) region in case of breach anytime in the future. The Chhombo Chhu watershed (CCW) of Tista basin in the Sikkim Himalaya (~694.5 km²) is located in the transitional zone between the Greater Himalayan range with a Tethyan Sedimentary Sequence, is the storehouse of number of glacial lakes covering large areas, and volume. In order to evaluate the critical glacial lakes, we mapped the changes between 1975–2018 and assessed their dynamics based on manual analysis of medium to high-resolution optical images for the years 1975, 1989, 2000, 2010 and 2018, respectively and verified during field surveys. Results show that the number of lakes has increased from 62 to 98, and its total area expanded significantly by ~34.6 ± 5.4%, i.e., from 8.5 ± 0.2 km² in 1975 to 11.4 ± 0.6 km² by 2018, at an expansion rate of 0.8 ± 0.1% a⁻¹. It is interesting to note that these lakes expanded faster during 2010–2018 (+1.18 ± 2.0% a^–1), i.e. in the recent decade, compared to previous years such as +1.02 ± 1.1% a^–1 in 1975–1988, +0.54 ± 1.3% a^–1 in 1988–2000 and +0.20 ± 1.6% a^–1 in 2000–2010. Lake outburst susceptibility result reveals that a total of twenty-seven potentially dangerous glacial lakes exist in the CCW; 5 have a status of ‘high’ outburst probability, 17 ‘medium’ and 5 ‘low’. Accelerating increasing long-term average annual trend of temperature (+0.283 °C a⁻¹; 1975–2013) at 95% confidence level also supports the glacier area lost (–0.66 ± 0.1% a^–1), and lake area enlargement trend (+0.80 ± 0.1% a^–1) between 1975 and 2018, indicating heightened impact of climate change in the CCW of the Sikkim Himalaya.

How to cite: Chowdhury, A., De, S. K., Sharma, M. C., and Debnath, M.: Glacial Lakes in the Chhombo Chhu Watershed (Sikkim Himalaya, India): Inventory, Classification, Evolution, and Potential GLOFs Assessment, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-19, https://doi.org/10.5194/icg2022-19, 2022.

The retreat of glaciers in response to climate warming leads to substantial changes not only in their mass balance, size and runoff but it also impacts their proglacial zones. A common characteristic of these proglacial changes is the development of glacial lake systems, which serve as meltwater and sediment reservoirs and become new elements in Arctic paraglacial landscapes. This paper investigates the evolution of a unique glacial lake system that has developed in the proglacial zone of the glacier system Cramerbraene in Svalbard since the termination of the Little Ice Age.

Our results indicate that the first glacial lakes appeared in the foreland of Crammerbreane in the late 1950s and early 1960s. Since then, the lake system has steadily increased in area concurrently with progressive retreat of Crammerbreane. In 2014, the first documented dam breaching of the terminal moraine occurred, leading to a glacial lake outburst flood (GLOF) event, which resulted in a loss of the lake area by 0.08 km². After this event, the lake area began to steadily increase again reaching its largest surface area in its development history in 2019: 0.44 km². In September 2019, a second and larger GLOF event occurred, reducing the lake area by 0.23 km² (~50%) within nine days. Recent satellite and aerial imagery indicates that the described lake system has been steadily draining since the 2019 GLOF event. More importantly, as a result of these two documented catastrophic glacial runoffs, the geomorphology in the foreland of Crammerbreane has been reworked, leading to changes in the course of the river channel that transports glacial water into Recherchefjorden.

            These findings suggest that glacial lake systems in Svalbard play an increasingly important role in paraglacial Arctic landscape transformation, not only as glacial water and sediment storage reservoirs but also as active agents of downstream geomorphological changes through episodic catastrophic GLOF events.

            This work was supported by Svalbard Integrated Arctic Earth Observing System [Airborne remote sensing campaign 2021] and the Research Council of Norway [333199].

How to cite: Wieczorek, I., Zagórski, P., Strzelecki, M., Yde, J., and Stachnik, Ł.: Multidecadal evolution of high arctic glacial lake systems and their role in landscape paraglaciation - a case study of crammerbraene, svalbard, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-112, https://doi.org/10.5194/icg2022-112, 2022.

Rock glaciers are ubiquitous debris landforms associated with periglacial slopes and derived from the past or present creep of mountain permafrost. Since the late 1990s, there has been an increasing interest in their dynamics and evolution in the face of climate change, which highlighted a general acceleration and growing occurrences of rock glacier destabilization and degradation. Changes of rock glacier creep and its evolution can affect: sediment transfer rates along mountain slopes, landscape evolution, localized hazard situations and hydrologic regime. Despite this high societal relevance, rock glacier kinematics remains poorly observed and their inventorying process has been uncoordinated worldwide, making their global assessment and comparison difficult. In this context, the International Permafrost Association (IPA) supported the creation of an Action Group dedicated to Rock Glacier Inventories and Kinematics (RGIK), which specifically aims to (1) coordinate the definition of standard guidelines for global inventorying and mapping rock glaciers, including information on their activity rate, and (2) promote rock glacier velocities (RGV) as a new associated product to the Essential Climate Variable (ECV) permafrost in the frame of the Global Climate Observation System (GCOS). This contribution summarizes the major achievements of the RGIK Action Group since its start in 2018, with an emphasis on definitions, guidelines for rock glacier inventories and further recommendations for kinematic characterization. This presentation is a community effort of the RGIK Action Group. 

How to cite: Vivero, S. and Pellet, C.: The Rock Glacier Inventories and Kinematics (RGIK) Action Group: status and future directions, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-478, https://doi.org/10.5194/icg2022-478, 2022.

Rock glaciers are key landforms of the Alpine periglacial environment that transfer large amounts of debris. To improve our knowledge of the variation in permafrost creep rates over the Holocene, we combined data on current surface movements with surface dating on two adjacent rock glaciers in the Western Swiss Alps, the so-called Yettes Condjà B and C rock glaciers (hereafter YC-B and YC-C). Surface movements have been monitored since 2000 using GNSS measurements, and since 2016 by complementary UAV surveys and daily oblique photographs taken by a webcam. Furthermore, we used Optically Stimulated Luminescence (OSL) for dating block samples in the front of both rock glaciers and Schmidt hammer exposure-age dating (SHD) on different transects.

YC-B is a very active landform that has developed on a steep and regular slope directly at the foot of a rock wall. Surface velocities display substantial interannual variations, from 0.4 m/a between 2005 and 2007, up to 3.5 m/a in 2015 and 2020. Cumulative displacements reached up to 49 m in 21 years. During the last decade, the rock glacier has been separated into two distinct parts by the progressive appearance of a scar in the steepest part of the landform. This suggests the onset of a destabilization phase of the rock glacier. In contrast, YC-C is much less dynamic, and its morphology and topography are more complex than YC-B. Its roots are occupied by a small debris-covered ice patch, and geophysical surveys suggest a high ice content in the landform. Velocities are much lower than in YC-B, with values between 0.1 and 0.4 m/a in the lowermost active sector. During the last 21 years, the cumulative displacement has been up to 6.5 m.

SHD revealed ages of around 7.00 to 9.00 ka towards the front of both rock glaciers, while OSL dating in the front yielded ages of 8.00 to 12.00 ka. Thus, the two rock glaciers would have started to develop during the Early Holocene (11.70–8.24 ka b2k), i.e. before the Holocene Thermal Maximum which, in the Alps, is dated between 9.55 and 6.35 ka b2k. Combining these ages with the length of the rock glaciers, we obtain a mean Holocene velocity of 0.3 m/a for YC-B and 0.4 m/a for YC-C. There is thus a strong discrepancy between the rock glacier ages and the current surface velocities, especially for YC-B. Indeed, the estimated mean velocities during the entire Holocene are two orders of magnitude lower than the current velocities for this rock glacier. This indicates a considerable increase in velocities in recent decades and that current creep rates are probably unprecedented. More generally, this raises several questions about the velocity variations of rock glaciers on a Holocene timescale.

How to cite: Lambiel, C., Vivero, S., de Meris, S., King, G., and Scapozza, C.: Long-term development and decoupled kinematics of two adjacent rock glaciers in the Swiss Alps, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-321, https://doi.org/10.5194/icg2022-321, 2022.

Rockglaciers have been identified by various authors in the South Shetlands archipelago in the Antarctic Peninsula region, with Serrano and Lopez-Martínez (2000) having described 9 rockglaciers and 11 protalus lobes in the islands. However, little is known about the deformation rates of rockglaciers and their response to climate change. Hurd rockglacier is located in the south part of Hurd Peninsula in Livingston Island. It occupies the floor of a small glacial valley that descends from about 301 m asl to sea-level, at False Bay, where it presentsa series of raised-marine terraces. The bedrock is the low-grade metamorphic sandstones, shales and greywackes Myers Bluff Formation. The valley shows steep rockwalls with extensive scree slopes and a small retreating valley glacier with a prominent frontal moraine, from where the rockglacier develops. The rockglacier body is ci 630 m long and 290 m wide and the surface shows pressure ridges and furrows, especially in the lower sector. The rockglacier front is 15-20 m high and shows a slope of c. 45º. We present a detailed geomorphic survey of Hurd rockglacier based on the analysis of drone-derived orthomosaics and digital surface models. The structure of the rockglacier was analysed using electrical resistivity tomography surveys, which allowed identifying a frozen body at depth. The kynematics was analysed using historical aerial photos of 1956/1957 and recent very high-resolution satellite imagery, showing average deformation rates of 10 to 30 cm/year during that period. D-GPS measurements of stakes in the rockglacier body measured annually since 2011 show deformation rates of ci. 8 to 15 cm/year. Permafrost boreholes located in the vicinity of the rockglacier are used to discuss its climate sensitivity.

How to cite: Vieira, G., Prates, G., Goyanes, G., de Pablo, M. A., Farzamian, M., Oliva, M., Correia, A., Valadares, A. P., Baptista, J., Mora, C., and Pina, P.: New observations on the kynematics of Hurd rockglacier (Livingston Island, Antarctic Peninsula), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-535, https://doi.org/10.5194/icg2022-535, 2022.

The potential of periglacial landforms in the context of palaeoclimatic interpretation seems non-controversial due to their connection to climate-driven permafrost conditions. Their utilisation for this purpose may, however, involve specific challenges. Many periglacial landforms represent transitional processes of certain duration rather than clearly defined single events. This complicates their palaeoclimatic interpretation along high risks of postdepositional disturbance by frost-related processes. The latter causes problems for any application of (numerical) dating techniques. For example, although per se suited for often boulder-dominated periglacial landforms, cosmogenic radionuclide dating (CRN) faces the problem that large sample sizes would be required to achieve reliable ages.

Schmidt-hammer exposure-age dating (SHD) has been successfully utilised for periglacial landforms during the past years. If independent age data allow establishing local/regional SHD age-calibration curves, it offers the fundamental advantage of obtaining large sample sizes (hundreds or even thousands of boulders). This is crucial for dating diachronous landforms or landforms potentially affected by postdepositional disturbance.

To highlight the potential of SHD the results of investigations on patterned ground and related features on Juvflye in Jotunheimen (South Norway) will be presented. Detailed chronological constraints on their age and period of active formation are still lacking, only their 'fossil' appearance noted in previous studies. Other information is, however, available, for example the present distribution of permafrost or its variability during the Holocene.

By applying a reliable local SHD age-calibration curve all studied patterned ground features seem to have become stabilised and inactive prior or around the onset of the Holocene Thermal Maximum. Whereas an altitudinal gradient with slightly longer activity at higher altitude was detected with sorted circles, no similar signal was detected for sorted stripes. Preliminary results from ongoing investigations point towards similar or even older ages for large solifluction lobes on Juvflye. Recent mophodynamic activity is restricted to minor frost-related processes and include micro-scale frost sorting features and solifluction terracettes.

Formation of all patterned ground features has ceased at the onset of the Holocene Thermal Maximum despite the fact that at least middle and higher altitudes of Juvflye have been underlain by permafrost during the entire Holocene (and still are). Their stabilisation seems, therefore, independent of fluctuations of the lower limit of permafrost. A lowering of the permafrost limit during late Holocene cooling towards the 'Little Ice Age' shows no influence with any recent activity restricted to micro-scale features only.

Summarising, even with numerous questions related to the formation of the periglacial landforms on Juvflye still existing, SHD stabilisation ages challenge the general application of large patterned ground features as palaeoclimatic indicators for permafrost. From a morphodynamic point of view the occurrence of permafrost per se cannot be the sole factor for efficient formation of patterned ground. Factors such as soil moisture, availability of suitable substrate etc. need to be taken into account. The formation of patterned ground and related large-sized periglacial landforms could well have be restricted to a relatively limited time period immediately following deglaciation during early Holocene.

How to cite: Winkler, S.: Schmidt-hammer exposure-age dating (SHD) of periglacial landforms and its potential for palaeoclimatic and morphodynamic interpretation, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-3, https://doi.org/10.5194/icg2022-3, 2022.

Debris cones represent a typical landform in temperate high mountain regions. These features show representative periglacial and nival processes in the frame of a dynamic equilibrium. In this work, two debris cones (ahead A and B) located in the “La Vueltona” study area in the Picos de Europa mountain range (N Spain) are analysed. The dynamics of these landforms was studied for a period of 10 years (2009-2018) by means of Digital Elevation Models (DEM) surveyed using a Terrestrial Laser Scanner (TLS). We used the steepest slope line (SSL calculated in the 2009 DEM) to understand the lineal dynamics of the studied debris cones for the whole period. Statistical methods based on multivariate data were used to model the altitude of every location along the SSL for the year 2018. These statistical models used as input the topographic data from 2009 to 2017. The modelled and surveyed altitude for the year 2018 were compared, showing a coherent performance of the modelling approach, with errors within the typical uncertainty of the surveying technique. The Vueltona debris cones showed a wavy dynamics along the SSL, which may be useful to predict their evolution in the short-term. The dynamics model could be extrapolated to other debris cones in temperate high mountain areas.

How to cite: de Sanjosé Blasco, J. J., Serrano Cañadas, E., López González, M., Alonso Pérez, E., and Gómez Gutiérrez, A.: Dynamics of the “La Vueltona” in Picos de Europa (Spain) debris cones during the period 2009-2018., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-124, https://doi.org/10.5194/icg2022-124, 2022.

Recent evidence has shown that Arctic regions have warmed about twice as much as elsewhere on the planet over the last decades, and that high-latitude periglacial processes and hydrological systems are deeply impacted by rising temperatures. The study presents recent results concerning the fluvial dynamics of a large periglacial river, the Lena River. The Lena river drains a large basin (2.9 million km²) entirely occupied by permafrost (77% with a deep and continuous permafrost). We had previously demonstrated that in the Lena basin, the climate change induces important increase in the river water discharge, that destabilizes the fluvial bed. Here we focus on the fluvial islands dynamics by examining islands with permafrost and islands without permafrost, such comparison being considered as a good indicator of the sensitivity of the hydrosytem to climate change. Island changes are precisely examined: morphological parameters of about 100 islands are surveyed using a GIS on seven series of aerial photographs and satellite images of a 100 km-long reach, for the 1967 – 2017 period. Furthermore, data obtained on several monitored islands allow to analyze the control factors.

Field surveys and monitoring of islands shows that within a zone of thick and continuous permafrost, the Lena floodplain is far from being thermally and geomorphologically homogenous: the floodplain rather consists of a juxtaposition of seasonally frozen islands and permanently frozen islands.  First, the analysis demonstrates that the two types of islands present different dynamics in terms of erosion and sedimentation. A major change is observed for islands with permafrost at the beginning of the 21^st century: they clearly underwent a stronger erosion for the last twenty years. During the same period, numerous small and non-frozen islands have been formed. Second, the morphological parameters are analyzed with respect to factors that play a major part: water discharge (duration of bar-full, bankfull and flood discharges, number and season of flood peaks…) and temperature of the river water and of the island ground. The submersion of islands during flooding do not deeply modify the thermal regime within the island ground. However, the duration of the discharge exceeding the bar-full level can induce a marked erosion of island bank, especially in summer. Thus, our study highlights the complexity of large river responses across Arctic periglacial environments.

How to cite: Gautier, E., Dépret, T., Thommeret, N., Costard, F., Mousset, M., Konstantinov, P., Fedorov, A., and Virmoux, C.: Response of a Large Periglacial River to the current Climate Change, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-290, https://doi.org/10.5194/icg2022-290, 2022.

Calcite cements are found within the glaciotectonically-deformed coarse-grained glaciofluvial sediments of the Saalian age (MIS 6) at the Koczery site (E Poland). Their sedimentation was controlled by the occurrence of permafrost (Mleczak et al., 2021). Under these conditions, aggradation rate of a glaciomarginal fan was high, and freezing of freshly-deposited sediments was relatively quick. Advancing ice sheet deformed these frozen glaciofluvial sediment in its foreland, creating single faults along with gently and tight folds. These deformed sediments were covered with a subglacial till creating a dome-like shaped landforms reassembling a Cupola hill. This calcite-cemented conglomerate occupies the uppermost part of coarse-grained glaciofluvial sediments. Its thickness ranges from 0.02–0.05 m up to 0.70 m and depends on the inter-limb angle of folds. The higher the inter-limb angle of folds, the thicker the conglomerate. Its greatest thickness is generally recorded on the lee side of major bed obstacles, i.e. glaciotectonically-deformed folds, in this case.

Precipitation of calcite within the glaciotectonically-deformed glaciofluvial sediments resulted from a progressive freezing of the basal water film that occurred on the side site of deformed structures. The water froze due to the drop in water pressure on the lee site of folds, which in turn led to the precipitation of calcite. The results of oxygen and carbon stable isotope studies (δ¹⁸O, δ¹³C) indicate limestone clasts embedded in the glaciofluvial deposits as the source of carbonates involved in the cementation process (δ¹⁸O from -6 to -3‰ V-PDB, δ¹³C – from -1.4 to +0.9‰ V-PDB). Two types of calcite cements were recognized in the studied conglomerate. Each of them is thought to be a record of different basal conditions during the ice-sheet advance. The precipitation of sparite cement took place during the early stages of freezing under open-system conditions (i.e. continuous flow of water within the film). Micrite cement which overlies the sparite one was precipitated during the final freezing under closed-system conditions (i.e. water flow in the film is dominated by locally produced water involved in the regelation sliding proces; Sharp et al., 1990). Moreover, it is known that micrite precipitates from water which is more supersaturated with respect to calcite than that from which sparite precipitates.

A thin (up to 1 mm thick) manganese-rich layer was registered between the layers of sparite and micrite cements. The precipitation of calcite is characterized by δ¹⁸O and δ¹³C values ranging from -6.9 up to -6.2‰ (V-PDB) and from -9.0 up to -5.5‰ (V-PDB), respectively. No significant differences in the isotope notation between micrite and sparite were observed, which clearly indicates similar parameters of the host water.

Mleczak, M., Woronko, B., Pisarska-Jamroży, M., Bujak, Ł., 2021. Permafrost as the main factor controlling the fluvial sedimentation style on glaciomarginal fans. Sedimentary Geology. 422, 105971. https://doi.org/10.1016/j.sedgeo.2021.105971

Sharp M., Tison J.L., Fierens G., 1990. Geochemistry of Subglacial Calcites: Implications for the Hydrology of the Basal Water Film. Arctic and Alpine Research, 22, 2, 141-152.

How to cite: Woronko, B., Ulbin, K., Skolasińska, K., Mirosław-Grabowska, J., Pisarska-Jamroży, M., Górska, M., and Apolinarska, K.: Calcite cementation as a result of subglacial processes - the Saalian ice-sheet case study, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-449, https://doi.org/10.5194/icg2022-449, 2022.

Glacial curvilineations (GCLs) are spectacular landforms recently discovered along southern periphery of the last Scandiavian Ice Sheet (SIS). They were first described in central Poland (Lesemann et al., 2010, 2014) as multiple parallel, winding ridges several metres high and up to several kilometres long, systematically arranged in groups occurring in tunnel valleys, which form a complex and extensive geomorphic network. Lesemann et al. (2010, 2014) hypothesised that GCLs were likely eroded from older sediments carved by channelised subglacial meltwater flows. More recently, Clark and Livingstone (2018) detected GCL sets along the southern margin of the Laurentide Ice Sheet and suggested that they were produced by subglacial slope failures in tunnel valleys or near the shores of subglacial lakes.

An inventory of GCLs occurrences along the SIS margin in Poland, Germany and Denmark based on the analysis of high-resolution LiDAR digital elevation models is presented. We document a total 59 GCL fields and focus on the geomorphic characteristics of the 43 most conspicuous ones. Each of these fields consists of smaller units called GCL swarms, 137 in total. Based on the landscape characteristics of the GCLs in relation to the tunnel valleys they occur in, three types of tunnel-valley relationships were distinguished: simple tunnel valleys, compound tunnel valleys and tunnel-valley complexes.

The morphological characteristics and internal composition support the origin of GCLs as erosional remnants of antecedent landscapes carved by pressurized meltwater flows in subglacial channels (Adamczyk et al., 2022).

This study was carried out as part of the scientific project financed by the National Science Centre (NCN) in Poland, project no. 2018/31/B/ST10/00976.

References

Adamczyk A., Wysota W., Piotrowski J. A., 2022. Inventory of glacial curvilineations (GCLs) at the southern periphery of the Scandinavian Ice Sheet. Geomorphology, 400, https://doi.org/10.1016/j.geomorph.2021.108094.

Clark, C.D. & Livingstone, S.J. (2018): Glacial curvilineations found along the southern sector of the Laurentide Ice sheet and a hypothesis of formation involving subglacial slope failure in tunnel valleys and subglacial lakes. ESPL 43, 1518–1528.

Lesemann, J.-E., Piotrowski, J.A. & Wysota, W. (2010): „Glacial curvilineations”: New glacial landforms produced by longitudinal vortices in subglacial meltwater flows. Geomorphology 120, 153-161.

Lesemann, J.-E., Piotrowski, J.A. & Wysota, W. (2014): Genesis of the ‘glacial curvilineation’ landscape by meltwater processes under the former Scandinavian Ice Sheet, Poland. Sedimentary Geology 312, 1-18.

How to cite: Wysota, W., Adamczyk, A., Piotrowski, J. A., and Weckwerth, P.: Glacial curvilineations (GCLs) at the southern periphery of the last Scandinavian Ice Sheet: distribution, morphological characteristics and origin, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-197, https://doi.org/10.5194/icg2022-197, 2022.

A wide variety of glacial sedimentary deposits and glacigenic landforms are found in southernmost Patagonia. These units were generated along the southeastern margin of the Patagonian Ice Sheet in the province of Santa Cruz (Argentina) and the Magallanes region of Chile (latitude 52º S and longitude 71º W).

The more extensive glaciation in this area was the Great Patagonian Glaciation (GPG, Mercer 1976), of Early Pleistocene age, probably developed during the Marine Isotope Stages (MIS) 30 and 32. The younger glaciations were defined as piedmont glaciations, developed during the Early and Middle Pleistocene.

In most cases, these ice flows displayed a piedmont lobe morphology, with wet-based glaciers, which generated a large variety of sub-glacial linear landforms. Other landforms occur as irregular crests, perpendicular to the direction of ice flow, with adjacent depressions, located in the higher portions of the ice lobes. 

This work is centred in the geomorphological studies of elongated sub-glacial features such as drumlins, flutes and megaflutes, but also of other landforms, much less frequent in Patagonia, as ribbed/Rögen moraines and eskers.

These ribbed/Rögen moraines present an average separation between crests of 400 m and a width of hundreds of m. The observed lengths vary between hundreds of m to km. The elevations vary from 5 to 20 m, from the highest to the lowest points of the adjacent depression. These features are similar to the ribbed/Rögen moraines described by Lundqvist (1989).

The ribbed/Rögen moraines are located in relict terrains, corresponding to the oldest glaciations of this area. They are part of a basal moraine of Early Pleistocene age. These features are rarely preserved because younger melt waters destroyed or buried the pre-existing landforms. In this case, the Rogen moraines have been preserved only in the highest portion of the basal moraines. Interference of the ice flow directions would have forced lower ice velocities and the possibility of cold-based glaciers development, which formed the ribbed/Rogen moraines found in the highest portions of the valley.

Consequently, a low basal velocity of the ice would have permitted the possibility of creating cold-based ice. The presence of scarce or absent melt water at the base of the ice could be explained because ice was far from the pressure melting point. Thus, this ice lobe would have been, at least partially a cold-based glacier, or even a polithermal glacier, that would have been replaced later on by a wet-based ice flow. Other aligned subglacial landforms are younger than the glaciation that formed the ribbed moraines. This paper shows that these linear landforms of sub-glacial origin are superimposed to an even older glacial landscape, characterized by ribbed/Rogen moraines.

How to cite: Rabassa, J., Ercolano, B., and Montero Estaña, P.: Geomorphology of subglacial ribbed-Rogen moraines of Early Pleistocene age, southernmost Patagonia, Argentina, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-70, https://doi.org/10.5194/icg2022-70, 2022.

Rapid climate changes during the Late Weichselian glaciation caused a sudden increase in meltwater activity and significantly transformed land relief. This transformation was accompanied by the supply of considerable quantities of meltwaters in glacial lakes in the southern periphery of the Scandinavian ice sheet. Their sudden release was responsible for the development of the Megaflood Landform System in north-eastern Poland which includes floodwater flow pathways represented by the Western and Eastern Spillways (Weckwerth et al., 2019). In the proximal part of the Western Spillway, the Bachanowo and Szeszupka Outburst Fans developed, while scabland-like topography was formed at the front of the Prudziszki Gate in proximal part of the Eastern Spillway. Bachanowo and Szeszupka Outburst Fans have surface characterized by the existence of subsequent bedforms, which include (1) streamlined bars developed as downstream elongated ridges and separated by channels of the braiding pattern, (2) scours with channel lag sediments deposited from traction carpet and gravel bedload sheets, (3) scour infills originated due to hydraulic jumps, and (4) expansion bars or chute bars evolved during the waning flood stage. These bars consist of sheet-like beds dipping downstream, and were formed due to low-angle forests progradation under condition of pulsed deposition from the traction carpet and fast sheetflows, the energy of which gradually decreased. As a common, an openwork texture was observed in sedimentary successions of all recognized features.

The bottom of proximal part of the Eastern Spillway at the front of Prudziszki Gate is characterised by butte-and-basin topography with landforms representing different types of bedforms typical for high-energy supercritical outflow. These include longitudinal furrows, transverse furrows, potholes, furrows of different shape, kettle holes and associate obstacle marks including lateral and frontal scours (Weckwerth et al., 2022). Transverse furrows are oriented perpendicular to the floodwater outflow and compose longitudinal clusters separated by ridges. Sedimentary successions of these ridges reflect a clear deposition cyclicity related to reactivated upstream progradation of scour infills and sedimentation on downflow-side of hydraulic jump.

The outburst fans and their characteristic bedforms were formed at the mouth of deep subglacial tunnel valleys, while the scabland-like topography developed at the mouth of flat-bottomed subglacial valleys which were transformed into open ice-walled canyons. The bedforms typical for outburst fans and the scabland-like topography consist of similar facies deposited due to flood outbursts emanating from two different englacial systems, but these facies form different associations related with changeable riverbed morphology transformed under condition of the upper flow regime.

This study was carried out as part of the scientific project financed by the National Science Centre (NCN) in Poland, project no. 2018/31/B/ST10/00976.

References

Weckwerth, P., Wysota W., Piotrowski J.A., Adamczyk A., Krawiec A., Dąbrowski M., 2019. Late Weichselian glacier outburst floods in North-Eastern Poland: landform evidence and palaeohydraulic significance. Earth-Sciences Review, 194, 216-233.

Weckwerth, P., Kalińska E., Wysota W., Krawiec A., Adamczyk A., Chabowski M., 2022. What does transverse furrow train in scabland-like topography originate from? The unique records of upper-flow-regime bedforms of a glacial lake-outburst flood in NE Poland. Quaternary International, 617, 40-58.

How to cite: Weckwerth, P., Kalińska, E., Wysota, W., Krawiec, A., and Chabowski, M.: Types of glacial outburst flood outlets differentiated by englacial feeding systems at the end of the Weichselian glaciation (NE Poland), 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-56, https://doi.org/10.5194/icg2022-56, 2022.

Large volumes of water were suddenly released from glacial lakes during the last glaciation leaving geomorphic signatures in the formerly glaciated areas. Large glacial lake outburst floods occurred in the Suwałki Lakeland, NE Poland possibly during two events at ca. 19 ka and shortly after 16 ka (Weckwerth et al., 2019). To chronologically frame the megaflood events, sediments from giant current dunes (megadunes) were sampled for optically stimulated luminescence (OSL) dating. 180-250 μm quartz grains from 22 samples were analysed as small (2-mm) single aliquots. Only one sample revealed relatively pure quartz extracts, whereas others suffered from significant feldspar contamination. The dating yielded a wide time span between ca. 17 ka and ca. 83 ka when applying the central age model (CAM). The minimum age model (MAM-3) was used for three samples providing a slightly younger age. All SAR-OSL inbuilt rigour checks for SAR-OSL dating was fulfilled by the data set, thus making all results methodologically reliable. Several samples fall in the preliminarily expected 19–16 ka time span, giving the ages between ca. 17 ka and ca. 18.8 ka. Large part of the samples is older than ca. 20 ka, which likely results from partial or incomplete bleaching, a phenomenon common in sediments of aqueous origin (Lang et al., 2018; Herget et al., 2020).

This study was supported by the scientific project financed by the National Science Centre (NCN) in Poland, project no. 2018/31/B/ST10/00976 and the project to develop international collaboration with the world’s top academic institutions by members of Emerging Fields under the Excellence Initiative – Research University programme (project no: 90-SIDUB.6102.9.2021.PMEF1) at Nicolaus Copernicus University in Toruń, Poland.

References:

Weckwerth, P., Wysota, W., Piotrowski, J.A., Adamczyk, A., Krawiec, A., Dąbrowski, M., 2019. Late Weichselian glacier outburst floods in North-Eastern Poland: Landform evidence and palaeohydraulic significance. Earth-Science Reviews 194, 216–233. doi:10.1016/j.earscirev.2019.05.006

How to cite: Kalinska, E., Weckwerth, P., Alexanderson, H., Piotrowski, J. A., and Wysota, W.: Dating a flood: the first attempt to determine the age of the outburst megadune deposits in NE Poland, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-177, https://doi.org/10.5194/icg2022-177, 2022.

Projections of future climate implicate the thickening of debris-covered glaciers. Thus it becomes
increasingly important to consider the influences of the debris layer on glacier melt especially
because of the strong non-linear relationship between debris thickness and ablation rate. This
relationship is known as the Østrem curve. For very thin debris layers ablation is increased due to a
higher albedo where as thicker debris layers reduce ablation due to insulation. Some local scale
models based on satellite images already partly account for this effect. They take the average debris
thickness per decametre large grid cells and scale the ablation based on a representative Østrem
curve. Unfortunately, supraglacial debris thickness has been shown to vary substantially over short
length scales on a glacier surface. The debris thickness frequency distribution is also non-linear, with
varying skew and kurtosis. Therefore sub-debris ice ablation is a result of the combined non-
linearities of the particular Østrem curve with the particular frequency distribution of the debris
thickness.
In this study, we investigate the error of the ablation rate introduced by neglecting debris frequency
distribution. We obtained the Østrem curves from field measurements and different numerical
models. A gamma distribution with different rate and shape parameters was used to represent likely
debris thickness frequency distribution. The analysis shows that the debris frequency distribution
has a strong effect on calculated glacier melt. For some cases, this can result in a doubling or
tripling of ablation values in comparison to that calculated using the mean debris thickness.
Therefore neglecting this effect in numerical models has the potential to drastically underestimate
glacier melt.
Within the framework of this study, an interactive application was developed that allows one to
investigate the error on ice ablation if not considering the debris layer's thickness frequency
distribution.

How to cite: Beck, C., Nicholson, L., Wirbel, A., and Simon, T.: Characterizing the role of supraglacial debris thickness variability on underlying ice ablation, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-325, https://doi.org/10.5194/icg2022-325, 2022.

Slovenia is situated at the border of the European Alps, the Pannonian Basin and the Dinaric Alps. Over 90 % of its surface is covered by sedimentary rocks, of which nearly half are carbonate rocks such as limestone and dolomite. During the Quaternary extensive glaciations occurred here which reshaped the surface and formed typical glacial landforms such as moraines, glacial troughs and circular hollows called glacial cirques. Glacial cirques typically form at higher elevations underneath mountain ridges. They are often characterized by an arcuate planform and concave profile. The morphogenesis of glacial cirques is tied to the subglacial erosion of a rotational glacial flow which involves the plucking of underlying bedrock and abrasion of the cirque floor with the entrained sediment. The analysis of morphometric and morphogenetic properties of glacial cirques allows for the interpretation of the type, duration and intensity of glaciation as well as the paleoclimate during the time of the formation of glacial cirques.

Glacial cirques in Slovenia have yet to be systematically studied. The first step towards this is the identification and classification of glacial cirques. The identification was performed manually using key morphographic (arcuate planform, location near ridges) and morphometric (slope, curvature) parameters of glacial cirques and using the LIDAR surface data with a spatial resolution of 1x1 m from the Slovenian Environment Agency. In the first stage 129 potential glacial cirques were identified in the three Slovenian mountain ranges (the Julian Alps, the Kamnik-Savinja Alps and the Karavanke Mountains). Relevant morphometric data (slopes, curvature, dimensions, aspect, size, circularity…) were then calculated for the identified landforms. Using hierarchical clustering methods (Ward, Gower, minimum linkage, complete linkage…) and morphometric data multiple quantitative classifications of glacial cirques were made.

The obtained classification of glacial cirques in Slovenia was objective, statistically supported and founded on quantitative data and as such is potentially applicable to populations of glacial cirques elsewhere. There is still an unsolved dilemma regarding the objectivity and reliability of the manual identification of potential glacial cirques, which could possibly be solved by implementing machine learning. This could lead to a completely automated and impartial identification of glacial cirques.

How to cite: Cof, K., Stepišnik, U., Žebre, M., and Lipar, M.: Classification of Glacial Cirques in Slovenia, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-347, https://doi.org/10.5194/icg2022-347, 2022.