Beyond confusion: Rock glaciers as cryo-conditioned landforms

Berthling, Ivar

doi:10.1016/j.geomorph.2011.05.002

Cited by 220 publications

(197 citation statements)

References 87 publications

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“…Conversely, ice rapidly melts in the concave rooting zone, disconnecting the flowing rock glaciers from the upslope vanishing glacier zones. The longterm individual flow of ice-debris mixtures, weakly sensitive to climatic variations, explains, therefore, the development of rock glaciers at the system margins (Ackert, 1998;Berthling, 2011). This illustrates the morphodynamical continuum that can exist between glacial and periglacial processes, which coexist or follow each other according to climatic variations in these permafrost environments (Benn et al, 2003;Whalley, 2009;Berthling et al, 2013).…”

Section: Genesis and Evolutionmentioning

confidence: 95%

“…In addition, current and recent surface morphology was analyzed with field observations, old oblique photographs that we collected, and numerous maps and aerial photographs available from the websites of national topographic institutes (map.geo.admin.ch and geoportail.gouv.fr; e.g., Figure 3). However, we considered surface morphology with care because confusion and controversy emerged from morphology-centered approaches and relatively hampered the knowledge construction on the complex landsystems study here (Berthling, 2011;Janke et al, 2015). To simplify the analysis, we tried to identify homogeneous sectors that share the same general ground electrical resistivities, surface dynamics and morphology in each study site.…”

Section: General Approachmentioning

confidence: 99%

“…In the system margins, rock glaciers can be present. They are related to the long-term slow viscous creep of ice/debris mixtures under permafrost conditions, which generates particular surface patterns like ridges and furrows and a fine-grained steep front (Benn et al, 2003;Berthling, 2011;Monnier and Kinnard, 2015). In contrast to the debris-covered glaciers, they do not have accumulation areas from a glaciological point of view.…”

Section: Introductionmentioning

confidence: 99%

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Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Bosson

Lambiel

2016

Front. Earth Sci.

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This contribution explores the internal structure of very small debris-covered glacier systems located in permafrost environments and their current dynamical responses to short-term climatic variations. Three systems were investigated with electrical resistivity tomography and dGPS monitoring over a 3-year period. Five distinct sectors are highlighted in each system: firn and bare-ice glacier, debris-covered glacier, heavily debris-covered glacier of low activity, rock glacier and ice-free debris. Decimetric to metric movements, related to ice ablation, internal deformation and basal sliding affect the glacial zones, which are mainly active in summer. Conversely, surface lowering is close to zero (−0.04 m yr −1 ) in the rock glaciers. Here, a constant and slow internal deformation was observed (c. 0.2 m yr −1 ). Thus, these systems are affected by both direct and high magnitude responses and delayed and attenuated responses to climatic variations. This differential evolution appears mainly controlled by (1) the proportion of ice, debris and the presence of water in the ground, and (2) the thickness of the superficial debris layer.

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Section: Genesis and Evolutionmentioning

confidence: 95%

Section: General Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Bosson

Lambiel

2016

Front. Earth Sci.

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“…Active rock glaciers are creeping landforms occurring in continuous or discontinuous permafrost areas with high-relief and suitable topoclimatic conditions. Such landforms move slowly downvalley or downslope and evolve over a period of several centuries to millennia (Barsch, 1996;Haeberli et al, 2006;Berthling, 2011;Krainer et al, 2015). Rock glaciers are commonly characterized by distinct flow structures with longitudinal and concave-downward bended transversal furrows and ridges at the surface.…”

Section: Introductionmentioning

confidence: 99%

The Dösen Rock Glacier in Central Austria: A key site for multidisciplinary long-term rock glacier monitoring in the Eastern Alps

Kellerer‐Pirklbauer

Lieb

Kaufmann

2018

AJES

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Rock glaciers are distinct landforms in high mountain environments indicating present or past permafrost conditions. Active rock glaciers contain permafrost and creep slowly downslope often forming typical flow structures with ridges and furrows related to compressional forces. Rock glaciers are widespread landforms in the Austrian Alps (c. 4600). Despite the high number of rock glaciers in Austria, only few of them have been studied in detail in the past. One of the best studied ones is the 950 m long Dösen Rock Glacier located in the Hohe Tauern Range. This rock glacier has been investigated since 1993 using a whole suite of fieldbased and remote sensing-based methods. Research focused on permafrost conditions and distribution, surface kinematics, internal structure and possible age of the landform. Results indicate significant ground surface warming of the rock glacier body during the period 2007-2015 accompanied by a general acceleration of the rock glacier surface flow velocity (max. 0.66 m/a) over the last two decades. This speed-up is possibly related to higher ice temperature and water content. As judged from various geophysical measurements, the maximum thickness of the rock glacier is about 30-40 m with an active layer of several meters depending on the location. The permafrost thickness beneath the active layer was quantified to be between 10 m (at the margins) and 40 m (at the central and upper parts). Massive sedimentary ice has not been observed or detected by geophysics so far at the central and lower part but might exist to in the rooting zone of the rock glacier as indicated from field evidences. The Dösen Rock Glacier is primarily a talus-derived rock glacier although a small glacier might have existed some times in the past in the eastern part of the rooting zone. Age estimations of the rock glacier by using the Schmidt-hammer exposure-age dating method indicate a formation period of several thousand years with alternating periods of faster and slower evolution. Research findings at this typical alpine rock glacier in the Austrian Alps clearly point out that the morphogenesis, the internal structure as well as the climaterock glacier relationship is complex but typical for such peculiar alpine landforms.________________________________________

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“…Rock glaciers are common in marginal glacial zones (Clark et al 1998) where debris cover insulates the ice core; this insulation effect effectively lowers the regional Equilibrium line altitude (ELA) (Clarke et al 1994). There has been significant debate over whether rock glaciers are periglacial or glacial landforms (Berthling 2011). Presently active rock glaciers appear to show a continuum from ice cored glacial landforms; to ice supported periglacial landforms promoted by permafrost (Hamilton and Whalley 1995, Clark et al 1998, Aoyama 2005.…”

Section: Rock Glaciersmentioning

confidence: 99%

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

Slee¹

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It is widely recognised that during the Late Quaternary, glaciation was limited in Australia, especially away from Tasmania. This contrasts with the widely recognised occurrence of periglacial landforms in SE Australia, particularly in Australian Alps and Tasmania.However, very little research has been undertaken into these landforms. The aim of this thesis is to investigate the extent and timing of Late Quaternary periglacial conditions in south-eastern Australia and to understand the geomorphic processes and environments associated with these landforms. This thesis presents an updated understanding of the distribution, morphology and climatic significance of periglacial landforms in eastern Australia. The thesis is divided into two sections. The first section is focused on modern 'active' periglacial landforms found primarily in the mountainous areas of Tasmania and focuses on two studies of modern freeze-thaw processes in western Tasmania. At higher elevations (1000 m) notable freeze-thaw features are active at the present time including stone banked lobes on Mt Rufus. Freeze-thaw features were identified to only 150 m above sea-level near Queenstown. However, these low elevation freeze-thaw landforms are small scale features associated with short periods where shallow ground ice forms.The second section of the thesis focuses on relict periglacial landforms that display no evidence of modern activity and most likely relate to late Quaternary cold climate conditions. It primarily focuses on the block deposits of eastern Australia, their morphology, distribution and climatic significance. Block deposits and associated landslide deposits from northern New South Wales to Tasmania were mapped. Four sites were studied in more detail and dated using surface exposure dating (SED). They yielded ages ranging from early Holocene to OIS 5 which are internally consistent within sites but vary widely between sites. These data provide evidence for repeated phases of periglacial activity during the last glacial cycle. At Guyra, several phases of mass movement were recognised with large scale landslides associated with a much earlier warm and humid climate dominating the landscape. Freeze-thaw landforms of the late Quaternary are superimposed on these older forms. The scale of last glaciation cooling is indicated by evidence for a possible nivation hollow bounded by a pronival rampart located near the town of Guyra (29°30'S). From this site a cooling range of 8-11°C is inferred, but additionally, relatively moist conditions are required for the nivation feature to form.The concept of a relatively humid glaciation also emerges from the mapping of the freezethaw landforms on a regional basis. In particular the occurrence of block deposits and screes in northern New England in patterns matching the modern precipitation gradient indicates that freeze-thaw was preferentially concentrated in a zone parallel to the coast. It is inferred that this zone represented an area of intermediate moisture landward of the divide separa...

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Beyond confusion: Rock glaciers as cryo-conditioned landforms

Cited by 220 publications

References 87 publications

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

The Dösen Rock Glacier in Central Austria: A key site for multidisciplinary long-term rock glacier monitoring in the Eastern Alps

The distribution and paleoclimate implications of periglacial landforms in eastern Australia

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