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Antoni G. Lewkowicz - One of the best experts on this subject based on the ideXlab platform.
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Frontal advance of turf-banked Solifluction lobes, Kluane Range, Yukon Territory, Canada
Geomorphology, 2005Co-Authors: Christophe Kinnard, Antoni G. LewkowiczAbstract:Humus horizons associated with thirteen Solifluction lobes on a single slope were radiocarbon dated at fixed distances behind the risers, as well as ahead of the lobes. The dated horizons, together with stratigraphic observations of planar discontinuities inside the lobes and shallow burial of vegetation ahead of the lobes, all suggest rapid advance of lobe fronts. We infer that lobe advance at this site results from slow accumulation of soliflucted material behind a relatively rigid riser, progressive steepening of the riser and build-up of stress, and finally rupture of the front and its collapse onto the slope. Rebuilding of the lobe usually then takes place. The time for a full cycle of development is estimated to be in the order of a few hundred years. Long-term frontal movement appears inversely related to lobe size, and is mainly controlled by soil moisture and sediment characteristics. These findings call into question the usefulness of Solifluction lobe advance rates for paleoclimate reconstructions, at least at this site.
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movement moisture and thermal conditions at a turf banked Solifluction lobe kluane range yukon territory canada
Permafrost and Periglacial Processes, 2005Co-Authors: Christophe Kinnard, Antoni G. LewkowiczAbstract:A turf-banked Solifluction lobe was instrumented for the continuous recording of surface and internal movement, thaw settlement, soil volumetric moisture content and thermal conditions during the spring and summer of 2002. Strain probe measurements showed that gelifluction occurred as a series of discrete and abrupt displacements near the thaw plane, followed by retrograde movement. Most gelifluction events took place when thaw rates were high and the soil was saturated almost to the surface, but rain was also capable of inducing gelifluction at depth. The rapid and localized character of the observed displacements suggests that gelifluction results from micro-shearing of the soil, possibly along the interface of thawing ice lenses. Copyright © 2005 John Wiley & Sons, Ltd.
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morphometry and environmental characteristics of turf banked Solifluction lobes kluane range yukon territory canada
Permafrost and Periglacial Processes, 2002Co-Authors: Chris H Hugenholtz, Antoni G. LewkowiczAbstract:Measurements of turf-banked Solifluction lobes at a site in the Kluane Range, Yukon Territory, are compared to observations made by L.W. Price of similar features located 50 km to the north in the Ruby Range. Both studies show that a threshold depth of snow is necessary for lobes to develop. The relative importance of Solifluction on slopes with different orientations, however, is not congruent. The largest lobes at our site are present on northeast-facing slopes and the smallest on northwest-facing slopes. Lobe dimensions increase downslope in association with a greater organic mat thickness, a higher soil fines content, and a reduced late-summer thaw depth. Riser heights that are large relative to tread length-to-width ratios are correlated with a thin organic mat, a thick active layer and a high coarse particle content. The lobe plan-form, described by the ratio of tread length to tread width, is significantly correlated with only one biophysical variable. Mean and median length-to-width ratios are below unity for all aspects at our site and in several other studies, suggesting a common evolutionary form. A cycle of Solifluction lobe development is proposed, in which a lobe enlarges to a maximum size that depends on micro-site environmental characteristics. Copyright © 2002 John Wiley & Sons, Ltd.
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LATE-SUMMER Solifluction AND ACTIVE LAYER DEPTHS, FOSHEIM PENINSULA, ELLESMERE ISLAND, CANADA
1998Co-Authors: Antoni G. Lewkowicz, Shawne ClarkeAbstract:Measurements of Solifluction using electro-mechanical meters over a period of 5 years at Hot Weather Creek (80iN, 84iW) show that summers with deep thaw produce enhanced rates of movement throughout the active layer. Within a basal transitional layer, the soil thaws and moves in some years but remains immobile and frozen in others. Predictions from a simple model involving displacements in a shear zone at the bottom of the active layer agree with measured subsurface movements below depths of 35-40 cm. This indicates that a shear zone, whose location depends on the depth of thaw, can explain the lower part of the velocity profile in this area of two-sided freezing, but that other processes, notably frost creep and isolated shearing, are important nearer the surface.
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A Solifluction meter for permafrost sites
Permafrost and Periglacial Processes, 1992Co-Authors: Antoni G. LewkowiczAbstract:A Solifluction meter that measures soil movements at eight levels in the active layer is described. Anchored in permafrost, the meter transforms mechanical movement of wooden blocks attached to flexible racks into changes in the electrical resistance of potentiometers. Solifluction can be monitored continuously with a data-logger or manually at intervals when visiting field sites. Preliminary results from meters installed on the Fosheim Peninsula, Ellesmere Island, illustrate frost creep, with heave continuing at ground temperatures between −25°C and −30°C, and summer movements of the active layer in response to thaw consolidation and precipitation. L'auteur decrit un appareil qui mesure dans la couche active les mouvements de sol a 8 profondeurs differentes. Ancre dans le pergelisol, l'appareil transforme le mouvement mecanique de blocs de bois, en modification de resistances electriques par l'intermediare de potentiometres. Les mouvements peuvent ětre enregistres de maniere continue ou ětre manuellement mesures quand les sites sont visitees. Des resultats preliminaires obtenus avec des appareils installes sur la Peninsule de Fosheim, sur l'ile d'Ellesmere, montrent des mouvements de reptation due au gel avec un soulevement qui continue a des temperatures de sol entre −25 et −30°C, et des mouvements d'ete de la couche active en reponse a la consolidation lors du degel ou a la suite de precipitations.
Christophe Kinnard - One of the best experts on this subject based on the ideXlab platform.
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Frontal advance of turf-banked Solifluction lobes, Kluane Range, Yukon Territory, Canada
Geomorphology, 2005Co-Authors: Christophe Kinnard, Antoni G. LewkowiczAbstract:Humus horizons associated with thirteen Solifluction lobes on a single slope were radiocarbon dated at fixed distances behind the risers, as well as ahead of the lobes. The dated horizons, together with stratigraphic observations of planar discontinuities inside the lobes and shallow burial of vegetation ahead of the lobes, all suggest rapid advance of lobe fronts. We infer that lobe advance at this site results from slow accumulation of soliflucted material behind a relatively rigid riser, progressive steepening of the riser and build-up of stress, and finally rupture of the front and its collapse onto the slope. Rebuilding of the lobe usually then takes place. The time for a full cycle of development is estimated to be in the order of a few hundred years. Long-term frontal movement appears inversely related to lobe size, and is mainly controlled by soil moisture and sediment characteristics. These findings call into question the usefulness of Solifluction lobe advance rates for paleoclimate reconstructions, at least at this site.
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movement moisture and thermal conditions at a turf banked Solifluction lobe kluane range yukon territory canada
Permafrost and Periglacial Processes, 2005Co-Authors: Christophe Kinnard, Antoni G. LewkowiczAbstract:A turf-banked Solifluction lobe was instrumented for the continuous recording of surface and internal movement, thaw settlement, soil volumetric moisture content and thermal conditions during the spring and summer of 2002. Strain probe measurements showed that gelifluction occurred as a series of discrete and abrupt displacements near the thaw plane, followed by retrograde movement. Most gelifluction events took place when thaw rates were high and the soil was saturated almost to the surface, but rain was also capable of inducing gelifluction at depth. The rapid and localized character of the observed displacements suggests that gelifluction results from micro-shearing of the soil, possibly along the interface of thawing ice lenses. Copyright © 2005 John Wiley & Sons, Ltd.
Jana Eichel - One of the best experts on this subject based on the ideXlab platform.
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unmanned aerial vehicle based mapping of turf banked Solifluction lobe movement and its relation to material geomorphometric thermal and vegetation properties
Permafrost and Periglacial Processes, 2020Co-Authors: Jana Eichel, Daniel Draebing, Teja Kattenborn, Johannes Antenor Senn, Lasse Klingbeil, Markus Wieland, Erik HeinzAbstract:Solifluction is one of the most widespread periglacial processes with low annual movement rates in the range of $^{-}$ millimeters to centimeters. Traditional methods to assess Solifluction movement usually have low spatial resolution, which hampers our understanding of spatial movement patterns and the factors controlling them. In this study, we (a) test the applicability of unmanned aerial vehicle (UAV)-based structurefrom-motion photogrammetry in comparison to a traditional total station survey tomap surface movement of a turf-banked Solifluction lobe (TBL) in the Turtmann Valley (Switzerland). We then (b) relate the detected movement patterns to potential geomorphometric, material, thermal and vegetation controls, which we assessed using geomorphic and vegetation mapping, electrical resistivity surveys and temperature loggers. Our results show that (a) UAV-based mapping can detect Solifluction movement with high spatial resolution (one point per m$^{2}$, total > 900 points) and rates and patterns consistent with a total station survey, but requires careful measurement set-up and analysis; and (b) movement rates differ between lobe tread, riser and a ridge feature. Differences can be explained by heterogeneous material, geomorphometric, thermal and vegetation properties of the TBL, which promote different Solifluction processes. Our study demonstrates the applicability of UAV-based mapping in Solifluction research and improves our understanding of Solifluction processes and landform development.
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Small-scale lobate hillslope features on Mars: A comparative 3D morphological study with terrestrial Solifluction lobes and zebra stripe lobes
Icarus, 2020Co-Authors: Renaldo Gastineau, Jana Eichel, Andreas Johnsson, Susan J. Conway, Nicolas Mangold, Peter Grindrod, Tatiana IzquierdoAbstract:Abstract Small-scale lobes (SSL) observed at the surface of Mars are thought to be the result of Solifluction. Hence, their existence has important implications for our understanding of recent climate history, the distribution of thaw liquids and its geomorphic effects, as water is believed not to have been recently stable at the martian surface. These small-scale lobes are limited to sloping terrains and often occur alongside polygonal patterned ground attesting to the presence of ice in the environment. In this study, we perform a comparative 3D morphometric analysis of the lobes on Mars with terrestrial analogues. We use data from High Resolution Imaging Science Experiment (HiRISE) camera in order to create Digital Terrain Models (DTMs) on Mars at 1 m/pix. For the terrestrial analogues, we use DTMs and orthophotos from five periglacial environments with Solifluction lobes and from one site with lobate features found in the Atacama Desert. The lobate features in the Atacama Desert are found within features called “zebra stripes”, which are apparently unique to the Atacama and are now generally accepted to be the result of seismic shaking. We show that SSL on Mars overlap morphometrically with terrestrial Solifluction lobes, and are less similar to zebra stripe lobes. The majority of martian SSL occur below the angle of repose which demonstrates that a dry fall mechanism cannot be responsible for their formation and that lubrication of the subsurface is required. We found that martian SSL only occur on slopes greater than ~10°, a constraint not observed for terrestrial Solifluction lobes nor zebra stripe lobes in Atacama. We hypothesise that this apparent constraint does not result from the lowered gravity on Mars, but instead from differing soil properties and/or thermal regime between Mars and Earth which affects the slope at which creep can initiate. We cannot rule out a role of CO2 sublimation in lobe-formation based on our terrestrial measurements.
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Solifluction meets vegetation the role of biogeomorphic feedbacks for turf banked Solifluction lobe development
Earth Surface Processes and Landforms, 2017Co-Authors: Jana Eichel, Daniel Draebing, Lasse Klingbeil, Markus Wieland, Heiner Kuhlmann, Christian Eling, Sebastian Schmidtlein, Richard DikauAbstract:Vegetation is an important factor influencing Solifluction processes, while at the same time, Solifluction processes and landforms influence species composition, fine-scale distribution and corresponding ecosystem functioning. However, how feedbacks between plants and Solifluction processes influence the development of turf-banked Solifluction lobes (TBLs) and their geomorphic and vegetation patterns is still poorly understood. We addressed this knowledge gap in a detailed biogeomorphic investigation in the Turtmann glacier foreland (Switzerland). Methods employed include geomorphic and vegetation mapping, terrain assessment with unmanned aerial vehicle (UAV) and temperature logging. Results were subsequently integrated with knowledge from previous geomorphic and ecologic studies into a conceptual model. Our results show that geomorphic and vegetation patterns at TBLs are closely linked through the lobe elements tread, risers and ridge. A conceptual four-stage biogeomorphic model of TBL development with ecosystem engineering by the dwarf shrub Dryas octopetala as the dominant process can explain these interlinked patterns. Based on this model, we demonstrate that TBLs are biogeomorphic structures and follow a cyclic development, during which the role of their components for engineer and non-engineer species changes. Our study presents the first biogeomorphic model of TBL development and highlights the applicability and necessity of biogeomorphic approaches and research in periglacial environments. Copyright © 2016 John Wiley & Sons, Ltd.
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spatial controls of turf banked Solifluction lobes and their role for paraglacial adjustment in glacier forelands
Permafrost and Periglacial Processes, 2017Co-Authors: Daniel Draebing, Jana EichelAbstract:In glacier forelands, Solifluction is a major and fast-responding paraglacial process in the adjustment of low- or moderately-inclined moraine slopes. However, the spatial pattern of the factors that control Solifluction and their interactions are poorly understood. In this study, we combine geomorphic and vegetation mapping, analysis of borehole material and time domain reflectometry with two-dimensional (2D) and three-dimensional (3D) electrical resistivity tomography (ERT) to quantify the controlling factors and evaluate their influence on sediment transport. The investigated turf-banked Solifluction lobe is located on the distal slope of a 1920s lateral moraine in the foreland of the Turtmann glacier in the southern Swiss Alps. Our data demonstrate the interaction between material, soil moisture and vegetation, which results in geomorphometric features such as (i) frontal and lateral risers, (ii) a lobe tread and (iii) a ridge. Lobe size indicates intense Solifluction movement in the last 100 years. The interaction of controlling factors results in a negative feedback which stabilises the lobe and, thus, limits paraglacial sediment transport to frost heave processes on the ridge. Copyright © 2016 John Wiley & Sons, Ltd.
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conditions for feedbacks between geomorphic and vegetation dynamics on lateral moraine slopes a biogeomorphic feedback window
Earth Surface Processes and Landforms, 2016Co-Authors: Jana Eichel, Dov Jeanfrancois Corenblit, Richard DikauAbstract:Little Ice Age lateral moraines represent one of the most important sediment storages and dynamic areas in glacier forelands. Following glacier retreat, simultaneous paraglacial adjustment and vegetation succession affect the moraine slopes. Geomorphic processes (e.g. debris flows, interrill erosion, gullying, Solifluction) disturb and limit vegetation development, while increasing vegetation cover decreases geomorphic activity. Thus, feedbacks between geomorphic and vegetation dynamics strongly control moraine slope development. However, the conditions under which these biogeomorphic feedbacks can occur are insufficiently understood and major knowledge gaps remain. This study determines feedback conditions through the analysis of geomorphic and vegetation data from permanent plots in the Turtmann glacier foreland, Switzerland. Results from multivariate statistical analysis (i) confirm that Dryas octopetala L. is an alpine ecosystem engineer species which influences geomorphic processes on lateral moraines and thereby controls ecosystem structure and function, and (ii) demonstrate that biogeomorphic feedbacks can occur once geomorphic activity sufficiently decreases for D. octopetala to establish and cross a cover threshold. In the subsequent ecosystem engineering process, the dominant geomorphic processes change from flow and slide to bound Solifluction. Increasing slope stabilization induces a decline in biogeomorphic feedbacks and the suppression of D. octopetala by shrubs. We conceptualize this relationship between process magnitude, frequency and species resilience and resistance to disturbances in a ‘biogeomorphic feedback window’ concept. Our approach enhances the understanding of feedbacks between geomorphic and alpine vegetation dynamics on lateral moraine slopes and highlights the importance of integrating geomorphic and ecological approaches for biogeomorphic research. Copyright © 2015 John Wiley & Sons, Ltd.
Antonio Gómez Ortiz - One of the best experts on this subject based on the ideXlab platform.
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Present-Day Solifluction Processes in the Semi-Arid Range of Sierra Nevada (Spain)
Arctic Antarctic and Alpine Research, 2014Co-Authors: Marc Oliva, Antonio Gómez Ortiz, Ferran Salvador Franch, Montserrat Salvà CatarineuAbstract:Abstract In the highest land of the Sierra Nevada National Park, an experiment to monitor Solifluction rates together with the thermal regime of the ground was implemented during the period 2005–2011. Data show evidence of the low activity of Solifluction processes in the present-day periglacial belt of Sierra Nevada. Annual displacement rates were lower than 1 cm yr-1 both in northern and southern slopes. Solifluction was more active near snow patches and streams. Rates were also higher during snowier years. Soil temperatures showed seasonal frost occurrence, though the depth and duration of the frozen layer is strongly conditioned by the annual snow cover. Water availability appears to be a crucial factor for Solifluction processes in this semiarid environment.
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The role of aridification in constraining the elevation range of Holocene Solifluction processes and associated landforms in the periglacial belt of the Sierra Nevada (southern Spain)
Earth Surface Processes and Landforms, 2010Co-Authors: Marc Oliva, Lothar Schulte, Antonio Gómez OrtizAbstract:Climate variability during the Mid-Late Holocene has influenced the activity of geomorphic processes in the current periglacial belt of the Sierra Nevada. We studied two types of sedimentary records that reveal a synchronous timing for slope instability in this high semi-arid massif: Solifluction landforms and mountain lake sediments. Lithological and sedimentological properties of both records have recorded numerous cycles of different magnitude of slope processes in the massif. Solifluction deposits record seven phases of Solifluction activity and soil development during the last 7 ka bp and lake sediments show evidence of eight periods with increased geomorphic activity in the catchments over the last 6 ka bp. Although present-day climate conditions do not promote active Solifluction processes in the Sierra Nevada, colder and wetter periods during the Holocene triggered Solifluction and transported coarse-grained sediments into the lakes. By contrast, warm phases favoured soil formation and spread an incipient vegetation cover over the headwaters of the highest valleys, diminishing the grain size of the particles reaching the lakes. Lake sediments record an aridification trend in the massif intensifying since 4·2 ka bp that has conditioned Solifluction activity to shift gradually to higher elevations. During major cooler phases such as the Little Ice Age active Solifluction was recorded back down to 2500 m altitude. Copyright © 2010 John Wiley & Sons, Ltd.
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Morphometry and Late Holocene activity of Solifluction landforms in the Sierra Nevada, southern Spain
Permafrost and Periglacial Processes, 2009Co-Authors: Marc Oliva, Lothar Schulte, Antonio Gómez OrtizAbstract:Numerous Solifluction landforms in two valleys of the western part of the Sierra Nevada range in the southern Iberian Peninsula were classified according to morphology and used to reconstruct Solifluction activity for the Late Holocene. Lobes are almost inactive under the current semiarid climate and water availability appears to be the crucial control on activity within the high-elevation study areas. The presence of numerous inactive Solifluction lobes suggests that past climate conditions must have been more favourable for lobe development. Chronostratigraphic profiles of several lobes indicate that colder and/or wetter periods (e.g. the Little Ice Age) tend to promote slope movements, with sparser vegetation cover and higher Solifluction rates whereas a denser vegetation cover spreads across valley floors and soils develop during warmer periods (e.g. the Medieval Warm Period). Copyright © 2009 John Wiley & Sons, Ltd.
Hanna Ridefelt - One of the best experts on this subject based on the ideXlab platform.
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Local variations of Solifluction activity and environment in the Abisko Mountains, Northern Sweden
Earth Surface Processes and Landforms, 2011Co-Authors: Hanna Ridefelt, Jan Boelhouwers, Bernd EtzelmüllerAbstract:Seven sites within the mountain region of Abisko, northern Sweden, were selected for measurement of Solifluction movement rates and correlation with the local environmental factors. Grids with size ...
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Spatial analysis of Solifluction landforms and process rates in the Abisko Mountains, northern Sweden
Permafrost and Periglacial Processes, 2010Co-Authors: Hanna Ridefelt, Bernd Etzelmüller, Jan BoelhouwersAbstract:The occurrence of turf-banked Solifluction landforms in the Abisko region was analysed using a grid-based approach and statistical modelling through logistic regression. Significant parameters in t ...
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56 years of Solifluction measurements in the abisko mountains northern sweden analysis of temporal and spatial variations of slow soil surface movement
Geografiska Annaler Series A-physical Geography, 2009Co-Authors: Hanna Ridefelt, Jan Boelhouwers, Jonas Akerman, Achim A Beylich, Else Kolstrup, Rolf NybergAbstract:Solifluction movement rates from 1952 to 2008 for the Abisko region, northern Sweden, have been compiled and analysed through correlation tests and multiple regression. The temporal analysis is b ...
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Spatial and Temporal Variations of Solifluction and Related Environmental Parameters in the Abisko Mountains, Northern Sweden
2009Co-Authors: Hanna RidefeltAbstract:Seven sites within the mountain region of Abisko, northern Sweden, were selected for measurement of Solifluction movement rates and correlation with the local environmental factors. Grids with sizes from 20 m x 30 m to 50 m x 100 m included both Solifluction landforms and adjacent ground. Positions of movement markers and the terrain were recorded and the grid areas were digitally reconstructed. This allowed topography, vegetation and soil texture (fraction of fine material) surfaces to be interpolated and used together with data on soil moisture in statistical analyses. Significant correlations differ from site to site indicating that environmental factors have varying importance and inter-relations depending on the local setting. Geomorphic work was also assessed within the grids. The results indicate measurable geomorphic work where no landforms are present. These areas may make larger contributions to sediment displacement than where Solifluction landforms exist. Solifluction is an important denudational agent in the region and has its greatest impact on landscape development in the western part of the region.
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Measurement of Solifluction rates using multi-temporal aerial photography
Earth Surface Processes and Landforms, 2009Co-Authors: Hanna Ridefelt, Jan Boelhouwers, Trond EikenAbstract:A new method is presented to assess decadal Solifluction lobe movement and volumetric changes at the catchmentscale. The method is based on photogrammetrical analysis of orthorectified repeat aeria ...
