scholarly journals New evidence for active talus-foot rock glaciers at Øyberget, southern Norway, and their development during the Holocene

The Holocene ◽  
2021 ◽  
pp. 095968362110332
Author(s):  
Atle Nesje ◽  
John A Matthews ◽  
Henriette Linge ◽  
Marie Bredal ◽  
Peter Wilson ◽  
...  
Keyword(s):  
Surface Layer ◽  
Regional Climate ◽  
Age Dating ◽  
Rock Glacier ◽  
The Holocene ◽  
Synthetic Aperture Radar Interferometry ◽  
Compressive Flow ◽  
Rock Glaciers ◽  
Southern Norway ◽  
Exposure Ages

Synthetic aperture radar interferometry (InSAR) measurements demonstrate that lobate, blocky depositional landforms, located in southern Norway at an altitude of ~530 m above sea level, with an estimated mean annual air temperature of ~1.6°C, currently exhibit deformation attributed to viscous creep. Five years of InSAR measurements for six lobes demonstrate average surface velocities of 1.2–22.0 mm/year with maximum rates of 17.5–55.6 mm/year. New Schmidt-hammer exposure-age dating (SHD) of two proximal lobes reveals mid-Holocene ages (7.6 ± 1.3 ka and 6.0 ± 1.2 ka), which contrast with the early-Holocene SHD and 10Be ages obtained previously from distal lobes, and late-Holocene SHD ages presented here from two adjacent talus slopes (2.3 ± 1.0 ka and 2.4 ± 1.0 ka). Although passive transport of boulders on the surfaces of these small, slow-moving rock glaciers affected by compressive flow means that the exposure ages are close to minimum estimates of the time elapsed since lobe inception, disturbance of boulders on rock glaciers is a source of potentially serious underestimates of rock-glacier age. Rock-glacier development at Øyberget began shortly after local deglaciation around 10 ka before present and continued throughout the Holocene in response to microclimatic undercooling within the coarse blocky surface layer of the talus and rock-glacier lobes. We suggest this enhanced cooling lowers mean annual surface-layer temperature by at least ~3.6°C, which is needed at such a low altitude to sustain sporadic permafrost and avoid fast thawing as atmospheric temperatures rise. Our results point to circumstances where inferences about rock glaciers as indicators of regional climate should be interpreted with caution, and where they may be less useful in palaeoclimatic reconstruction than previously thought.

scholarly journals Evidence for rapid paraglacial formation of rock glaciers in southern Norway from 10Be surface-exposure dating

2020 ◽  
Vol 97 ◽  
pp. 55-70 ◽  
Author(s):  
Henriette Linge ◽  
Atle Nesje ◽  
John A. Matthews ◽  
Derek Fabel ◽  
Sheng Xu
Keyword(s):  
Climatic Conditions ◽  
Rock Glacier ◽  
Surface Exposure Dating ◽  
Exposure Dating ◽  
Environmental Controls ◽  
Short Period ◽  
Rock Glaciers ◽  
Valley Site ◽  
Southern Norway ◽  
Exposure Ages

AbstractWe evaluate the timing and environmental controls on past rock-glacier activity at Øyberget, upper Ottadalen, southern Norway, using in situ 10Be surface-exposure dating on (1) boulders belonging to relict rock-glacier lobes at c. 530 m asl, (2) bedrock and boulder surfaces at the Øyberget summit (c. 1200 m asl), and (3) bedrock at an up-valley site (c. 615 m asl). We find that the rock-glacier lobes became inactive around 11.1 ± 1.2 ka, coeval with the timing of summit deglaciation (11.2 ± 0.7 ka). This is slightly older than previously published Schmidt-hammer surface-exposure ages. The timing does not match known climatic conditions promoting rock-glacier formation in the early Holocene; hence we infer that lobe formation resulted from enhanced debris supply and burial of residual ice during and soon after deglaciation. The results demonstrate that rock glaciers may form over a relatively short period of time (hundreds rather than thousands of years) under non-permafrost conditions and possibly indicate a paraglacial type of process.

scholarly journals Age constraints of rock glaciers in the Southern Alps/New Zealand – Exploring their palaeoclimatic potential

The Holocene ◽  
2018 ◽  
Vol 28 (5) ◽  
pp. 778-790 ◽  
Author(s):  
Stefan Winkler ◽  
Christophe Lambiel
Keyword(s):  
New Zealand ◽  
Southern Alps ◽  
Early Holocene ◽  
Age Dating ◽  
Schmidt Hammer ◽  
Rock Glacier ◽  
Glacier Surface ◽  
The Holocene ◽  
Exposure Age ◽  
Rock Glaciers

Two rock glaciers in the valley head of Irishman Stream in the central Ben Ohau Range, Southern Alps/New Zealand, have been investigated using the electronic Schmidt-hammer (SilverSchmidt). Longitudinal profiles on both features reveal a consistent trend of decreasing R(Rebound)-values and, hence, increasing weathering intensity and surface-exposure age on their numerous transverse surface ridges from rooting zone towards the front. Previously published numerical ages obtained by terrestrial cosmogenic nuclide dating (TCND) allowed the calculation of a local Schmidt-hammer exposure-age dating (SHD) age-calibration curve by serving as the required fixed points. Age estimates for the lowermost rock glacier surface ridges fall within the early Holocene between 12 and 10.5 ka and indicate a fast disappearance of the Late Glacial glacier formerly occupying the valley head, followed by the initiation of rock glacier formation around or shortly after the onset of the Holocene. Although it cannot be judged whether the rock glaciers investigated were active within the entire Holocene or only repeatedly during multiple episodes within, their location and intact morphology exclude any substantial glacial activity at Irishman Stream during the Holocene. This has considerable regional palaeoclimatic implications because it opens for the hypothesis that climatic conditions during early Holocene were possibly comparatively dry and favourable for rock glacier initiation, but less so for glaciers. It would also challenge the view that air temperature is the sole major climate driver of glacier variability in the Southern Alps. More work utilising the palaeoclimatic potential of rock glaciers in the Southern Alps is advised.

Schmidt-hammer exposure-age dating (SHD) of rock glaciers in the Schöderkogel-Eisenhut area, Schladminger Tauern Range, Austria

The Holocene ◽  
2011 ◽  
Vol 22 (7) ◽  
pp. 761-771 ◽  
Author(s):  
Matthias Rode ◽  
Andreas Kellerer-Pirklbauer
Keyword(s):  
Root Zone ◽  
Age Dating ◽  
Surface Velocity ◽  
Schmidt Hammer ◽  
Rock Glacier ◽  
Relative Age ◽  
Exposure Age ◽  
Rock Glaciers ◽  
Glacier Length ◽  
Eastern Austria

Schmidt-hammer rebound values ( R-values) enable relative-age dating of landforms, with R-values relating to degree of weathering and therefore length of exposure. This method – recently termed as Schmidt-hammer exposure-age dating (SHD) – was applied to date five rock glaciers (size range, 0.01–0.12 km2) and one recent rockfall deposit at the study area Schöderkogel-Eisenhut, in the Schladminger Tauern Range (14°03′E, 47°15′N), Austria. The rock glaciers consist of gneiss or high metamorphic series of mica-schist that are comparable in their R-values. Four of them are relict (permafrost absent) and one is intact (containing patches of permafrost). On each of the five rock glaciers, SHD was carried out at 4–6 sites (50 measurements per site) along a longitudinal transect from the frontal ridge to the root zone. Results at all five rock glaciers are generally consistent with each other sharing statistically significant R-values along transects. The range between the highest and the lowest mean R-value at each of the five rock glaciers is 9.9–5.2. Using rock glacier length and surface velocity data from nearby sites, the rock glacier development must have lasted for several thousand years. Furthermore, by using SHD results from rock glaciers of known age from other sites in the region with comparable geology, approximate surface ages of 6.7–11.4 ka were estimated. This indicates long formation periods for all five rock glaciers. Our results suggest that many of the 1300 relict rock glaciers in central and eastern Austria were formed over a long period during the Lateglacial and Holocene period.

Palaeoclimatic and morphodynamic implications of Holocene boulder-dominated periglacial and paraglacial landforms in Rondane, South Norway

2021 ◽  
Author(s):  
Philipp Marr ◽  
Stefan Winkler ◽  
Svein Olaf Dahl ◽  
Jörg Löffler
Keyword(s):  
Slope Failure ◽  
Rock Slope ◽  
Control Point ◽  
Alluvial Fan ◽  
Age Dating ◽  
The Holocene ◽  
Holocene Thermal Maximum ◽  
Exposure Age ◽  
Thermal Maximum ◽  
Exposure Ages

<p>Periglacial, paraglacial and related boulder-dominated landforms constitute a valuable, but often unexplored source of palaeoclimatic and morphodynamic information. The timing of landform formation and stabilization can be linked to past cold climatic conditions which offers the possibility to reconstruct cold climatic periods. In this study, Schmidt-hammer exposure-age dating (SHD) was applied to a variety of boulder-dominated landforms (sorted stripes, blockfield, paraglacial alluvial fan, rock-slope failure) in Rondane, eastern South Norway for the first time. On the basis of an old and young control point a local calibration curve was established from which surface exposure ages of each landform were calculated. The investigation of formation, stabilization and age of the respective landforms permitted an assessment of Holocene climate variability in Rondane and its connectivity to landform evolution. The obtained SHD age estimates range from 11.15 ± 1.22 to 3.99 ± 1.52 ka which shows their general inactive and relict character. Most surface exposure ages of the sorted stripes cluster between 9.62 ± 1.36 and 9.01 ± 1.21 ka and appear to have stabilized towards the end of the ‘Erdalen Event’ or in the following warm period prior to ‘Finse Event’. The blockfield age with 8.40 ± 1.16 ka indicates landform stabilization during ‘Finse Event’, around the onset of the Holocene Thermal Maximum (~8.0–5.0 ka). The paraglacial alluvial fan with its four subsites shows age ranges from 8.51 ± 1.63 to 3.99 ± 1.52 ka. The old exposure age points to fan aggradation follow regional deglaciation due to paraglacial processes, whereas the younger ages can be explained by increasing precipitation during the onset neoglaciation at ~4.0 ka. Surface exposure age of the rock-slope failure with 7.39 ± 0.74 ka falls into a transitional climate period towards the Holocene Thermal Maximum (~8.0–5.0 ka). This indicates that climate-driven factors such as decreasing permafrost depth and/or increasing hydrological pressure negatively influence slope stability. Our obtained first surface exposure ages from boulder-dominated landforms in Rondane give important insights to better understand the palaeoclimatic variability in the Holocene.</p>

10BE SURFACE EXPOSURE AGES FROM RELICT TALUS-DERIVED ROCK GLACIER LOBES AT ØYBERGET, SOUTHERN NORWAY

2018 ◽  
Author(s):  
Henriette Linge ◽  
◽  
John A. Matthews ◽  
Atle Nesje ◽  
Derek Fabel ◽  
...  
Keyword(s):  
Rock Glacier ◽  
Southern Norway ◽  
Exposure Ages

scholarly journals A two-sided approach to estimate heat transfer processes within the active layer of the Murtèl–Corvatsch rock glacier

2014 ◽  
Vol 2 (1) ◽  
pp. 141-154 ◽  
Author(s):  
M. Scherler ◽  
S. Schneider ◽  
M. Hoelzle ◽  
C. Hauck
Keyword(s):  
Heat Transfer ◽  
Surface Layer ◽  
Energy Balance ◽  
Active Layer ◽  
Heat Sink ◽  
Air Flow ◽  
Swiss Alps ◽  
Rock Glacier ◽  
Transfer Processes ◽  
Rock Glaciers

Abstract. The thermal regime of permafrost on scree slopes and rock glaciers is characterized by the importance of air flow driven convective and advective heat transfer processes. These processes are supposed to be part of the energy balance in the active layer of rock glaciers leading to lower subsurface temperatures than would be expected at the lower limit of discontinuous high mountain permafrost. In this study, new parametrizations were introduced in a numerical soil model (the Coup Model) to simulate permafrost temperatures observed in a borehole at the Murtèl rock glacier in the Swiss Alps in the period from 1997 to 2008. A soil heat sink and source layer was implemented within the active layer, which was parametrized experimentally to account for and quantify the contribution of air flow driven heat transfer on the measured permafrost temperatures. The experimental model calibration process yielded a value of about 28.9 Wm−2 for the heat sink during the period from mid September to mid January and one of 26 Wm−2 for the heat source in the period from June to mid September. Energy balance measurements, integrated over a 3.5 m-thick blocky surface layer, showed seasonal deviations between a zero energy balance and the calculated sum of the energy balance components of around 5.5 Wm−2 in fall/winter, −0.9 Wm−2 in winter/spring and around −9.4 Wm−2 in summer. The calculations integrate heat exchange processes including thermal radiation between adjacent blocks, turbulent heat flux and energy storage change in the blocky surface layer. Finally, it is hypothesized that these deviations approximately equal unmeasured freezing and thawing processes within the blocky surface layer.

scholarly journals A two-sided approach to estimate heat transfer processes within the active layer of rock glacier Murtèl-Corvatsch

2013 ◽  
Vol 1 (1) ◽  
pp. 141-175 ◽  
Author(s):  
M. Scherler ◽  
S. Schneider ◽  
M. Hoelzle ◽  
C. Hauck
Keyword(s):  
Heat Transfer ◽  
Surface Layer ◽  
Energy Balance ◽  
Active Layer ◽  
Heat Sink ◽  
Air Flow ◽  
Swiss Alps ◽  
Rock Glacier ◽  
Transfer Processes ◽  
Rock Glaciers

Abstract. The thermal regime of permafrost in scree slopes and rock glaciers is characterized by the importance of air flow driven convective and advective heat transfer processes. These processes are supposed to be part of the energy balance in the active layer of rock glaciers leading to lower subsurface temperatures than would be expected at the lower limit of discontinues high mountain permafrost. In this study, new parameterizations were introduced in a numerical soil model to simulate permafrost temperatures observed in a borehole at rock glacier Murtèl in the Swiss Alps in the period from 1997 to 2008. A soil heat sink and source layer was implemented within the active layer which was parameterized experimentally to account for and quantify the contribution of air flow driven heat transfer on the measured permafrost temperatures. The experimental model calibration process yielded a value of about 28.9 Wm−2 for the heat sink during the period from mid September to mid January and one of 26 Wm−2 for the heat source in the period from June to mid September. Energy balance measurements, integrated over a 3.5 m thick blocky surface layer, showed seasonal deviations between a zero energy balance and the calculated sum of the energy balance components of around 6.8 Wm−2 in fall/winter, −2.2 Wm−2 in winter/spring and around −5.6 Wm−2 in summer. The calculations integrate heat exchange processes including thermal radiation between adjacent blocks, turbulent heat flux and energy storage change in the blocky surface layer. Finally, it is hypothesized that these deviations approximately equal unmeasured freezing and thawing processes within the blocky surface layer.

ICE-CORED ROCK GLACIERS IN ANTARCTICA: RECORDING GLACIAL ADVANCES FROM MARINE ISOTOPE STAGE 5 TO THE HOLOCENE

2019 ◽  
Author(s):  
Kate M. Swanger ◽  
◽  
Kelsey Winsor ◽  
Esther Babcock ◽  
Rachel D. Valletta ◽  
...  
Keyword(s):  
Marine Isotope Stage ◽  
The Holocene ◽  
Rock Glaciers ◽  
Marine Isotope Stage 5

scholarly journals Observations on a Debris-Covered Polar Glacier “Whisky Glacier”, James Ross Island, Antarctic Peninsula, Antarctica

1987 ◽  
Vol 33 (115) ◽  
pp. 300-310 ◽  
Author(s):  
T.J.H. Chinn ◽  
A. Dillon
Keyword(s):  
Antarctic Peninsula ◽  
Rock Glacier ◽  
Freezing Front ◽  
Extensive Area ◽  
Free Zone ◽  
Rock Glaciers ◽  
James Ross Island ◽  
Polythermal Glacier ◽  
Powerful Mechanism

Abstract“Whisky Glacier” on James Ross Island, Antarctic Peninsula, comprises anévéand clean ice trunk surrounded by an extensive area of debris-covered ice resembling a rock glacier. The debris-free trunk of the glacier abuts abruptly against the broad, totally debris-covered tongue at a number of concentric zones where debris-laden beds crop out at the surface in a manner similar to the “inner moraine” formations of many polar glaciers.Ice structures and foliation suggest that “Whisky Glacier” is a polythermal glacier which is wet-based under the debris-free zone, and dry-based under the debris-covered zone. It is surmised that the glacier sole crosses the freezing front close to where the basal debris beds are upwarped towards the surface. Here, basal water is confined, and freezes to the under side of the glacier in thick beds of regelation ice which are uplifted to the surface along with the debris-laden beds. Ablation losses effectively cease beneath the blanket of debris covering the tongue.The transition from wet-based to dry-based conditions at the glacier sole is a powerful mechanism for entraining debris into a glacier and, in the case of “Whisky Glacier”, for lifting debris to the surface. It is suggested that this may be a mechanism for forming some polar rock glaciers.

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