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.

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.

Reconstruction of the dynamics and origin of rock glaciers in an Alpine environment

2021 ◽  
Author(s):  
Benjamin Lehmann ◽  
Robert S. Anderson ◽  
Xavier Bodin ◽  
Pierre G. Valla ◽  
Julien Carcaillet
Keyword(s):  
Remote Sensing ◽  
Time Scales ◽  
Surface Velocity ◽  
Rock Glacier ◽  
Alpine Environment ◽  
Mountain Ranges ◽  
Long Time ◽  
Rock Glaciers ◽  
Alpine Environments ◽  
Alpine Valleys

<p>Rock glaciers are one of the most frequent cryospheric landform in mid-latitude mountain ranges. They influence the evolution of alpine environments on short (years to decades) and long (centuries to millennia) time scales. As a visible expression of mountain permafrost [1] as well as an important water reserve in the form of ground ice [2], rock glaciers are seen as increasingly important in the evolution of geomorphology and hydrology of mountain systems in the context of climate change and deglaciation [3, 4]. On longer time scales, rock glaciers transport boulders produced by the erosion of the headwall upstream and downstream and therefore participate in shaping mountain slopes [5]. Despite their importance, the dynamics and origin of rock glaciers are poorly understood.</p><p>In this study, we propose to address two questions:</p><p>1) How does the dynamics of rock glaciers change over time?</p><p>2) What is the origin of rock glaciers and what is their influence on the evolution of alpine environments?</p><p>These two questions require an evaluation of the surface velocity field of rock glaciers by relating short and long time scales. To solve this problem, we combine complementary methods including remote sensing, geochronology with a mechanical model of rock glacier dynamics. We apply this approach to the rock glacier complex of the Vallon de la Route in the Massif du Combeynot (French alps).</p><p>In order to reconstruct the displacement field of the rock glacier on modern time scales, we used remote sensing methods (i.e., image correlation and InSAR). Over longer periods (10<sup>3</sup> to 10<sup>4</sup> years), we used cosmogenic terrestrial nuclides (TCN) dating. By applying this methodology to boulder surfaces at different positions along the central flow line of the rock glacier, from the headwall to its terminus, we will be able to convert the exposure ages into surface displacement. The use of dynamic modelling of rock glaciers [6] will allow us to relate the surface kinematics to short to long time scales. It will then be possible to discuss the age, origin of rock glaciers and how topo-climatic and geomorphological processes control their evolution in Alpine environment.</p><p> </p><p>[1] Barsch, D.: Rockglaciers. Indicators for the Present and Former Geoecology in High Mountain Environments, Springer series in physical environment vol. 16, Springer, Berlin, Heidelberg, 1996.</p><p>[2] Jones, D. B., Harrison, S., Anderson, K., and Whalley, W. B.: Rock glaciers and mountain hydrology: A review, Earth-Sci Rev, 193, 66–90, 2019.</p><p>[3] Haeberli, W., Schaub, Y., and Huggel, C.: Increasing risks related to landslides from degrading permafrost into new lakes in deglaciating mountain ranges, Geomorphology, 293, 405–417, 2017.</p><p>[4] Knight, J., Harrison, S., and Jones, D. B.: Rock glaciers and the geomorphological evolution of deglacierizing mountains, Geomorphology, 324, 14–24, 2019.</p><p>[5] MacGregor, K.R., Anderson, R.S., Waddington, E.D.: Numerical modeling of glacial erosion and headwall processes in alpine valleys. Geomorphology 103 (2):189–204, 2009.</p><p>[6] Anderson, R. S., Anderson, L. S., Armstrong, W. H., Rossi, M. W., & Crump, S. E.: Glaciation of alpine valleys: The glacier–debris-covered glacier–rock glacier continuum. Geomorphology, 311, 127-142, 2018.</p>

scholarly journals Snow-avalanche boulder fans in Jotunheimen, southern Norway: Schmidt-hammer exposure-age dating, geomorphometrics, dynamics and evolution

2020 ◽  
Vol 102 (2) ◽  
pp. 118-140
Author(s):  
John A. Matthews ◽  
Stefan Haselberger ◽  
Jennifer L. Hill ◽  
Geraint Owen ◽  
Stefan Winkler ◽  
...  
Keyword(s):  
Age Dating ◽  
Snow Avalanche ◽  
Schmidt Hammer ◽  
Exposure Age ◽  
Southern Norway

Holocene alluvial fan evolution, Schmidt‐hammer exposure‐age dating and paraglacial debris floods in the SE Jostedalsbreen region, southern Norway

Boreas ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 886-902
Author(s):  
John A. Matthews ◽  
Lindsey J. McEwen ◽  
Geraint Owen ◽  
Sietse Los
Keyword(s):  
Alluvial Fan ◽  
Age Dating ◽  
Schmidt Hammer ◽  
Exposure Age ◽  
Southern Norway ◽  
Debris Floods
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