scholarly journals First evidence of rock wall permafrost in the Pyrenees (Vignemale peak, 3,298 m a.s.l., 42°46′16″N/0°08′33″W)

2021 ◽  
Author(s):  
Ibai Rico ◽  
Florence Magnin ◽  
Juan Ignacio López Moreno ◽  
Enrique Serrano ◽  
Esteban Alonso‐González ◽  
...  
Keyword(s):  
Rock Wall

scholarly journals Investigation of a cold-based ice apron on a high-mountain permafrost rock wall using ice texture analysis and micro-14C dating: a case study of the Triangle du Tacul ice apron (Mont Blanc massif, France)

2021 ◽  
pp. 1-8
Author(s):  
Grégoire Guillet ◽  
Susanne Preunkert ◽  
Ludovic Ravanel ◽  
Maurine Montagnat ◽  
Ronny Friedrich
Keyword(s):  
Radiocarbon Dating ◽  
Boundary Migration ◽  
Ice Core ◽  
Ice Cores ◽  
Shear Plane ◽  
High Mountain ◽  
14C Dating ◽  
Rock Wall ◽  
Major Mechanism ◽  
Mont Blanc Massif

Abstract The current paper studies the dynamics and age of the Triangle du Tacul (TDT) ice apron, a massive ice volume lying on a steep high-mountain rock wall in the French side of the Mont-Blanc massif at an altitude close to 3640 m a.s.l. Three 60 cm long ice cores were drilled to bedrock (i.e. the rock wall) in 2018 and 2019 at the TDT ice apron. Texture (microstructure and lattice-preferred orientation, LPO) analyses were performed on one core. The two remaining cores were used for radiocarbon dating of the particulate organic carbon fraction (three samples in total). Microstructure and LPO do not substantially vary with along the axis of the ice core. Throughout the core, irregularly shaped grains, associated with strain-induced grain boundary migration and strong single maximum LPO, were observed. Measurements indicate that at the TDT ice deforms under a low strain-rate simple shear regime, with a shear plane parallel to the surface slope of the ice apron. Dynamic recrystallization stands out as the major mechanism for grain growth. Micro-radiocarbon dating indicates that the TDT ice becomes older with depth perpendicular to the ice surface. We observed ice ages older than 600 year BP and at the base of the lowest 30 cm older than 3000 years.

The Soldier Ghaut Petroglyphs on Montserrat, Lesser Antilles

2021 ◽  
pp. 1-9
Author(s):  
John F. Cherry ◽  
Krysta Ryzewski ◽  
Susana Guimarães ◽  
Christian Stouvenot ◽  
Sarita Francis
Keyword(s):  
European Union ◽  
Vertical Wall ◽  
Landscape Archaeology ◽  
Public Access ◽  
Lesser Antilles ◽  
Distribution Map ◽  
Rock Wall ◽  
Lighting Conditions ◽  
Blank Spot

Only five years ago, Montserrat was a blank spot on the distribution map of islands in the Lesser Antilles where petroglyphs were known. In January 2016, hikers in Soldier Ghaut, a deeply incised watercourse in the northwest of the island, came upon a panel of nine petroglyphs engraved on a nearly vertical wall of volcanoclastic tuff. Soon afterward the petroglyphs were documented by the Survey and Landscape Archaeology on Montserrat project (SLAM). Then in January 2018 an additional petroglyph was spotted on a large slab of rock, detached from the rock wall on the opposite side of the ghaut. At the invitation of the Montserrat National Trust (MNT) and with European Union funding, Susana Guimarães and Christian Stouvenot traveled to Montserrat in 2018 to assist in further studies at the site. They conducted photogrammetric documentation and photography under enhanced lighting conditions and inspected the petroglyphs and their context in detail in order to advise MNT about their conservation and provisions for public access. This report presents this new group of petroglyphs and their landscape setting and considers questions of dating and interpretation.

Rock hardness identification based on optimized PNN and multi-source data fusion

2021 ◽  
pp. 095440622110420
Author(s):  
Ying He ◽  
Muqin Tian ◽  
Jiancheng Song ◽  
Junling Feng
Keyword(s):  
Neural Network ◽  
Data Fusion ◽  
Probabilistic Neural Network ◽  
Wavelet Packet ◽  
Differential Evolution Algorithm ◽  
Vibration Signal ◽  
Optimization Method ◽  
Rock Wall ◽  
Rock Hardness ◽  
Source Data

To solve the problem that it is difficult to identify the cutting rock wall hardness of the roadheader in coal mine, a recognition method of cutting rock wall hardness is proposed based on multi-source data fusion and optimized probabilistic neural network. In this method, all kinds of cutting signals (the vibration signal of cutting arm, the pressure signal of hydraulic cylinders and current signal of cutting motor) are analyzed by wavelet packet to extract the feature vector, and the multi feature signal sample database of rock cutting with different hardness is established. To solve the problems of uncertain spread and complex network structure of probabilistic neural network (PNN), a PNN optimization method based on differential evolution algorithm (DE) and QR decomposition was proposed, and the rock hardness was identified based on multi-source data fusion by optimizing PNN. Then, based on the ground test monitoring data of a heavy longitudinal roadheader, the method is applied to recognize the cutting rock hardness, and compared with other common pattern recognition methods. The experimental results show that the cutting rock hardness recognition based on multi-source data fusion and optimized PNN has higher recognition accuracy, and the overall recognition error is reduced to 6.8%. The recognition of random cutting rock hardness is highly close to the actual. The method provides theoretical basis and technical premise for realizing automatic and intelligent cutting of heading face.

scholarly journals A custom acoustic emission monitoring system for harsh environments: application to freezing-induced damage in alpine rock walls

2012 ◽  
Vol 1 (2) ◽  
pp. 155-167 ◽  
Author(s):  
L. Girard ◽  
J. Beutel ◽  
S. Gruber ◽  
J. Hunziker ◽  
R. Lim ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Monitoring System ◽  
Detection Threshold ◽  
Liquid Water Content ◽  
Cold Climate ◽  
Harsh Environments ◽  
Time Data ◽  
Rock Wall ◽  
Hazard Surveillance ◽  
Common Technique

Abstract. We present a custom acoustic emission (AE) monitoring system designed to perform long-term measurements on high-alpine rock walls. AE monitoring is a common technique for characterizing damage evolution in solid materials. The system is based on a two-channel AE sensor node (AE-node) integrated into a wireless sensor network (WSN) customized for operation in harsh environments. This wireless architecture offers flexibility in the deployment of AE-nodes at any position of the rock wall that needs to be monitored, within a range of a few hundred meters from a core station connected to the internet. The system achieves near real-time data delivery and allows the user to remotely control the AE detection threshold. In order to protect AE sensors and capture acoustic signals from specific depths of the rock wall, a special casing was developed. The monitoring system is completed by two probes that measure rock temperature and liquid water content, both probes being also integrated into the WSN. We report a first deployment of the monitoring system on a rock wall at Jungfraujoch, 3500 m a.s.l., Switzerland. While this first deployment of the monitoring system aims to support fundamental research on processes that damage rock under cold climate, the system could serve a number of other applications, including rock fall hazard surveillance or structural monitoring of concrete structures.

scholarly journals Naididae (Annelida, Oligochaeta) associated with briophytes in Brotas, State of São Paulo, Brazil

2007 ◽  
Vol 24 (2) ◽  
pp. 518-519 ◽  
Author(s):  
Guilherme Rossi Gorni ◽  
Roberto da Gama Alves
Keyword(s):  
Fresh Water ◽  
First Record ◽  
Sao Paulo ◽  
São Paulo ◽  
Rock Wall

Mosses and liverworts can be colonized by various invertebrates, including fresh water oligochaete worms. However, little information is available on the habits and habitats of this oligochaetes in Brazil. Therefore, the present study was undertaken to examine the occurrence of naidids in mosses, as well as to broaden the knowledge about the habitats of these oligochaetes. Sampling of bryophytes adhered to rock substrates in the rapids of the Jacaré Pepira River (municipality of Brotas, São Paulo, Brazil) and to a vertical rock wall of a waterfall near the river revealed 191 Naididae individuals of the species Naiscommunis Piguet, 1906, Pristinellajenkinae (Stephenson, 1931) and Pristinellamenoni (Aiyer, 1929). We believe this to be the first record of naidids associated with mosses in Brazil.

The Arkhyz Savior A Rock-Wall Icon in Nizhnii Arkhyz, Karachay-Cherkessia (Russia)

IKON ◽  
2016 ◽  
Vol 9 ◽  
pp. 197-206
Author(s):  
Svetlana V. Cheloukhina
Keyword(s):  
Rock Wall

High alpine rock-wall retreat rates over millennia through thermo-cryogenic pre-conditioned rock fall (Mt. Eiger, Switzerland)

2021 ◽  
Author(s):  
David Mair ◽  
Alessandro Lechmann ◽  
Romain Delunel ◽  
Serdar Yeşilyurt ◽  
Dmitry Tikhomirov ◽  
...  
Keyword(s):  
Swiss Alps ◽  
Rock Fall ◽  
Rock Wall ◽  
Rock Face ◽  
Depth Profiles ◽  
Weathering Processes ◽  
Temperature Conditions ◽  
Low Efficiency ◽  
Cryogenic Processes

<p>Rock fall processes of various size and magnitude control retreat rates of high alpine rock-walls. For millennial time scales, these retreat rates can be quantified in-situ from concentrations of cosmogenic nuclides along bedrock depth profiles (Mair et al., 2019). We measured cosmogenic <sup>36</sup>Cl and <sup>10</sup>Be along several such profiles at Mt Eiger in the Central Swiss Alps to study the local rock-wall retreat on this time scale (Mair et al., 2019; 2020). The resulting spatial pattern shows that rock-wall retreat rates are low (0.5 to 0.6 ± 0.1 mm/yr) in the higher region of the NW rock-wall, in contrast to both the lower part of the NW rock-wall and the SE face, where rates are high (1.7 ± 0.4 to 3.5 ± 1.4 mm/yr). We link these retreat rates to differences in local temperature conditions, because the patterns of faults and fractures and the lithology of the bedrock are similar at all sites, and thermo-cryogenic processes are known to weaken the bedrock through fracturing, thereby preconditioning the occurrence of rock fall (e.g., Draebing and Krautblatter, 2019). However, it is still unclear how effective and at which rate individual thermo-cryogenic processes contribute to the preconditioning through fracturing. Therefore, we investigate several processes and estimate the probability of bedrock fracturing through the employment of a theoretical frost-cracking model, which predicts cracking intensity from ice segregation. The model results infer a low efficiency in the higher region of the NW rock-wall, but a relatively high one in the lower section of the NW wall and on the SE rock face of Mt. Eiger. Although the model is rather generic, the results disclose a significant control of temperature conditions on the erosional processes and rates. Furthermore, temperature conditions for the last millennia have been similar to present day conditions, as our reconstructions disclose, therefore the cosmogenic-nuclide-based long-term differences in rock-wall retreat rates predominantly stem from large contrasts in the microclimate between the NW and SE walls of Mt. Eiger. Accordingly, the site-specific differences in microclimate conditions could explain the lower retreat rates in the upper part of the NW rock-wall and the rapid retreat in the SW face and in the lower part of the NW rock face.</p><p>References</p><p>Draebing, D. and Krautblatter, M.: The Efficacy of Frost Weathering Processes in Alpine Rockwalls, Geophys. Res. Lett., 46, 6516–6524, doi:10.1029/2019GL081981, 2019.</p><p>Mair, D., Lechmann, A., Yesilyurt, S., Tikhomirov, D., Delunel, R., Vockenhuber, C., Akçar, N. and Schlunegger, F.: Fast long-term denudation rate of steep alpine headwalls inferred from cosmogenic 36Cl depth profiles, Sci. Rep., 9, 11023, doi:10.1038/s41598-019-46969-0, 2019.</p><p>Mair, D., Lechmann, A., Delunel, R., Yeşilyurt, S., Tikhomirov, D., Vockenhuber, C., Christl, M., Akçar, N. and Schlunegger, F.: The role of frost cracking in local denudation of steep Alpine rockwalls over millennia (Eiger, Switzerland), Earth Surf. Dyn., 8, 637–659, doi:10.5194/esurf-8-637-2020, 2020.</p>

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