scholarly journals Ice Segregation as an Origin for Lenses of Non-Glacial Ice in “Ice-Cemented” Rock Glaciers

1981 ◽  
Vol 27 (97) ◽  
pp. 506-510 ◽  
Author(s):  
William J. Wayne
Keyword(s):  
Groundwater Flow ◽  
Large Scale ◽  
Water Pressure ◽  
Snow Melt ◽  
Total Thickness ◽  
Rock Glacier ◽  
Glacial Ice ◽  
Substantial Loss ◽  
Rock Glaciers ◽  
Ice Segregation

AbstractIn order to flow with the gradients observed (10° to 15°) rock glaciers cannot be simply ice-cemented rock debris, but probably contain masses or lenses of debris-free ice. The nature and origin of the ice in rock glaciers that are in no way connected to ice glaciers has not been adequately explained. Rock glaciers and talus above them are permeable. Water from snow-melt and rain flows through the lower part of the debris on top of the bedrock floor. In the headward part of a rock glacier, where the total thickness is not great, if this groundwater flow is able to maintain water pressure against the base of an aggrading permafrost, segregation of ice lenses should take place. Ice segregation on a large scale would produce lenses of clear ice of sufficient size to permit the streams or lobes of rock debris to flow with gradients comparable to those of glaciers. It would also account for the substantial loss in volume that takes place when a rock glacier stabilizes and collapses.

scholarly journals Ice Segregation as an Origin for Lenses of Non-Glacial Ice in “Ice-Cemented” Rock Glaciers

1981 ◽  
Vol 27 (97) ◽  
pp. 506-510 ◽  
Author(s):  
William J. Wayne
Keyword(s):  
Groundwater Flow ◽  
Large Scale ◽  
Water Pressure ◽  
Snow Melt ◽  
Total Thickness ◽  
Rock Glacier ◽  
Glacial Ice ◽  
Substantial Loss ◽  
Rock Glaciers ◽  
Ice Segregation

AbstractIn order to flow with the gradients observed (10° to 15°) rock glaciers cannot be simply ice-cemented rock debris, but probably contain masses or lenses of debris-free ice. The nature and origin of the ice in rock glaciers that are in no way connected to ice glaciers has not been adequately explained. Rock glaciers and talus above them are permeable. Water from snow-melt and rain flows through the lower part of the debris on top of the bedrock floor. In the headward part of a rock glacier, where the total thickness is not great, if this groundwater flow is able to maintain water pressure against the base of an aggrading permafrost, segregation of ice lenses should take place. Ice segregation on a large scale would produce lenses of clear ice of sufficient size to permit the streams or lobes of rock debris to flow with gradients comparable to those of glaciers. It would also account for the substantial loss in volume that takes place when a rock glacier stabilizes and collapses.

scholarly journals Photo-Interpretation of two Types of Rock Glacier in the Colorado Front Range, U.S.A.

1965 ◽  
Vol 5 (42) ◽  
pp. 849-856 ◽  
Author(s):  
Samuel I. Outcalt ◽  
James B. Benedict
Keyword(s):  
Wall Rock ◽  
Colorado Front Range ◽  
Front Range ◽  
Rock Glacier ◽  
Floor Rock ◽  
Glacial Ice ◽  
Photo Interpretation ◽  
Two Generations ◽  
Rock Glaciers ◽  
Small Valley

AbstractTwo types of rock glacier occur in the Colorado Front Range. Rock glaciers on the floors of modern cirques closely resemble the tongues of small valley glaciers. Because they contain cores of banded glacial ice and grade up-valley into lateral moraines, rock glaciers of this type are believed to represent the debris-covered tongues of former glaciers. Most consist of two or more superimposed lobes, bounded by longitudinal furrows, and resulting from independent ice advances. Despite their compound nature, the complexes now appear to be moving down-slope as single units. Two generations of “cirque-floor” rock glaciers, both tentatively dated as being of post-Pleistocene age, occur in the Front Range.Rock glaciers of an entirely different character occur beneath steep valley walls, where they are supplied with debris by avalanche couloirs. Interstitial ice, responsible for the movement of “valley-wall” rock glaciers, probably results from the metamorphism of snow buried beneath rock-fall debris or supplied by winter avalanching.

scholarly journals Short-term velocity variations at three rock glaciers and their relationship with meteorological conditions

2016 ◽  
Vol 4 (1) ◽  
pp. 103-123 ◽  
Author(s):  
V. Wirz ◽  
S. Gruber ◽  
R. S. Purves ◽  
J. Beutel ◽  
I. Gärtner-Roer ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Ground Surface ◽  
Climatic Conditions ◽  
Water Infiltration ◽  
High Temporal Resolution ◽  
Rock Glacier ◽  
Short Term ◽  
Rock Glaciers ◽  
Velocity Variations

Abstract. In recent years, strong variations in the speed of rock glaciers have been detected, raising questions about their stability under changing climatic conditions. In this study, we present continuous time series of surface velocities over 3 years of six GPS stations located on three rock glaciers in Switzerland. Intra-annual velocity variations are analysed in relation to local meteorological factors, such as precipitation, snow(melt), and air and ground surface temperatures. The main focus of this study lies on the abrupt velocity peaks, which have been detected at two steep and fast-moving rock glacier tongues ( ≥  5 m a−1), and relationships to external meteorological forcing are statistically tested.The continuous measurements with high temporal resolution allowed us to detect short-term velocity peaks, which occur outside cold winter conditions, at these two rock glacier tongues. Our measurements further revealed that all rock glaciers experience clear intra-annual variations in movement in which the timing and the amplitude is reasonably similar in individual years. The seasonal decrease in velocity was typically smooth, starting 1–3 months after the seasonal decrease in temperatures, and was stronger in years with colder temperatures in mid winter. Seasonal acceleration was mostly abrupt and rapid compared to the winter deceleration, always starting during the zero curtain period. We found a statistically significant relationship between the occurrence of short-term velocity peaks and water input from heavy precipitation or snowmelt, while no velocity peak could be attributed solely to high temperatures. The findings of this study further suggest that, in addition to the short-term velocity peaks, the seasonal acceleration is also influenced by water infiltration, causing thermal advection and an increase in pore water pressure. In contrast, the amount of deceleration in winter seems to be mainly controlled by winter temperatures.

Photo-Interpretation of two Types of Rock Glacier in the Colorado Front Range, U.S.A.

1965 ◽  
Vol 5 (42) ◽  
pp. 849-856 ◽  
Author(s):  
Samuel I. Outcalt ◽  
James B. Benedict
Keyword(s):  
Wall Rock ◽  
Colorado Front Range ◽  
Front Range ◽  
Rock Glacier ◽  
Floor Rock ◽  
Glacial Ice ◽  
Photo Interpretation ◽  
Two Generations ◽  
Rock Glaciers ◽  
Small Valley

Abstract Two types of rock glacier occur in the Colorado Front Range. Rock glaciers on the floors of modern cirques closely resemble the tongues of small valley glaciers. Because they contain cores of banded glacial ice and grade up-valley into lateral moraines, rock glaciers of this type are believed to represent the debris-covered tongues of former glaciers. Most consist of two or more superimposed lobes, bounded by longitudinal furrows, and resulting from independent ice advances. Despite their compound nature, the complexes now appear to be moving down-slope as single units. Two generations of “cirque-floor” rock glaciers, both tentatively dated as being of post-Pleistocene age, occur in the Front Range. Rock glaciers of an entirely different character occur beneath steep valley walls, where they are supplied with debris by avalanche couloirs. Interstitial ice, responsible for the movement of “valley-wall” rock glaciers, probably results from the metamorphism of snow buried beneath rock-fall debris or supplied by winter avalanching.

Seasonal melting simulation of permafrost rock glaciers and their potential contribution to sediment loads in Alpine catchments

2020 ◽  
Author(s):  
Lucas Reid ◽  
Ulrike Scherer ◽  
Erwin Zehe
Keyword(s):  
Large Scale ◽  
Sediment Load ◽  
Series Data ◽  
Rock Glacier ◽  
Erosion Model ◽  
Permafrost Rock ◽  
Sediment Loads ◽  
Rock Glaciers ◽  
High Sediment ◽  
Seasonal Melting

<p>A common issue with large scale erosion modelling is that local processes are often unaccounted for, either because they haven’t been included in the model conceptually, or because they are undetected yet. On the other hand, significant deviations from such a general soil erosion model to the measurements can reveal those local processes. We compared the average yearly sediment amounts of a network of turbidity measurement stations in the catchment of the alpine River Inn to the results of the large scale erosion model RUSLE2015 (Panagos et. al.) for long term yearly erosion amounts and found a significant underestimation of sediment loads in three sub catchments. An important source of sediments in alpine rivers comes from glaciers, which explains the high loads in one of the stations, but two of the three high sediment load sub catchments are too low to have substantial valley glaciers. But another potential source of glacial sediment exists in the form of permafrost soils and in this case a specific permafrost form: rock glaciers. Rock glaciers in particular have been spotted in those two high sediment load catchments, but since they are hard to detect from remote sensing due to the surface being covered with rocks, the existence or the exact spatial extent is often unknown. But with rising temperatures in the Alps, the areas in which permafrost rock glaciers can exist decreases every year and the depth of the seasonal melting layer increases.</p><p>We propose the hypothesis that the high sediment loads in those sub catchments are caused by increasingly deeper melting of permafrost rock glaciers. This process releases fine materials which have been trapped frozen since the glacial period and are now being eroded and transported to the alpine streams. To get an estimation of potential erodible material from rock glacier melting in the respective sub catchments, we developed a model to simulate the heat diffusion from the air into the frozen ground, while accommodating for the change in specific thermal capacity. The model (developed in Python) takes air temperature time series data as input and can be configured for varying ground stratification setups with different thermal diffusivity values depending on the ground properties.</p><p>From the simulated melting depth of an average square meter of rock glacier we extrapolate the mass of melted material to the potential permafrost erosion material available in the River Inn sub catchments. We show that this source of sediments can be significant and needs to be factored in should an erosion model be used to calculate sediment input into the rivers. But, with the estimation of sediment load from permafrost origins narrowed down, improving a large-scale erosion model like the RUSLE2015 for this alpine mountain region by accounting for local processes like this one is possible. </p>

scholarly journals Detecting Rock Glacier Displacement in the Central Himalayas Using Multi-Temporal InSAR

2021 ◽  
Vol 13 (23) ◽  
pp. 4738
Author(s):  
Xuefei Zhang ◽  
Min Feng ◽  
Hong Zhang ◽  
Chao Wang ◽  
Yixian Tang ◽  
...  
Keyword(s):  
Deformation Rate ◽  
Large Scale ◽  
Parameters Estimation ◽  
Least Square ◽  
Rate Variation ◽  
Rock Glacier ◽  
Ridge Estimator ◽  
Central Himalayas ◽  
Multi Temporal ◽  
Rock Glaciers

Rock glaciers represent typical periglacial landscapes and are distributed widely in alpine mountain environments. Rock glacier activity represents a critical indicator of water reserves state, permafrost distribution, and landslide disaster susceptibility. The dynamics of rock glacier activity in alpine periglacial environments are poorly quantified, especially in the central Himalayas. Multi-temporal Interferometric Synthetic Aperture Radar (MT-InSAR) has been shown to be a useful technique for rock glacier deformation detection. In this study, we developed a multi-baseline persistent scatterer (PS) and distributed scatterer (DS) combined MT-InSAR method to monitor the activity of rock glaciers in the central Himalayas. In periglacial landforms, the application of the PS interferometry (PSI) method is restricted by insufficient PS due to large temporal baseline intervals and temporal decorrelation, which hinder comprehensive measurements of rock glaciers. Thus, we first evaluated the rock glacier interferometric coherence of all possible interferometric combinations and determined a multi-baseline network based on rock glacier coherence; then, we constructed a Delaunay triangulation network (DTN) by exploiting both PS and DS points. To improve the robustness of deformation parameters estimation in the DTN, we combined the Nelder–Mead algorithm with the M-estimator method to estimate the deformation rate variation at the arcs of the DTN and introduced a ridge-estimator-based weighted least square (WLR) method for the inversion of the deformation rate from the deformation rate variation. We applied our method to Sentinel-1A ascending and descending geometry data (May 2018 to January 2019) and obtained measurements of rock glacier deformation for 4327 rock glaciers over the central Himalayas, at least more than 15% detecting with single geometry data. The line-of-sight (LOS) deformation of rock glaciers in the central Himalayas ranged from −150 mm to 150 mm. We classified the active deformation area (ADA) of all individual rock glaciers with the threshold determined by the standard deviation of the deformation map. The results show that 49% of the detected rock glaciers (monitoring rate greater than 30%) are highly active, with an ADA ratio greater than 10%. After projecting the LOS deformation to the steep slope direction and classifying the rock glacier activity following the IPA Action Group guideline, 12% of the identified rock glaciers were classified as active and 86% were classified as transitional. This research is the first multi-baseline, PS, and DS network-based MT-InSAR method applied to detecting large-scale rock glaciers activity.

Distribution and characteristics of rock glaciers in the southern part of Jasper National Park, Alberta

1978 ◽  
Vol 15 (4) ◽  
pp. 540-550 ◽  
Author(s):  
B. H. Luckman ◽  
K. J. Crockett
Keyword(s):  
Little Ice Age ◽  
National Park ◽  
Ice Age ◽  
Rock Glacier ◽  
Genetic Classification ◽  
Climatic Fluctuations ◽  
Glacial Ice ◽  
Jasper National Park ◽  
Rock Glaciers ◽  
Two Phases

One hundred and nineteen rock glaciers were identified in an aerial photograph inventory of 4632 km2 in Jasper National Park, Alberta. Morphological subdivision indicated 33 lobate, 76 tongue-shaped and 10 spatulate rock glaciers, whereas a 'genetic' classification identified 65 'glacial' (ice-cored) and 54 'non-glacial' (ice-cemented) rock glaciers. Head elevations of the glacial group (mean 2318 m) are significantly higher than the non-glacial group (mean 2256 m). The total elevation range of rock glaciers is 1710–2670 m.Optimal rock glacier sites are below north- or northeast-facing quartzite cliffs in cirques or on valley walls. These topographic and geologic controls produce a greater concentration of rock glaciers in the Main Ranges than the Front Ranges. Rock glacier head elevations rise eastwards and, to a lesser extent, southward across the area in response to regional climatic and latitudinal effects. Two phases of pre-'Little Ice Age' rock glacier activity are recognized on morphologic grounds and, since Little Ice Age glaciers overrode most of the evidence of Holocene glacier fluctuation, provide a major source of information on Holocene climatic fluctuations. Preliminary data suggest most rock glacier activity pre-dates the Little Ice Age and the oldest phases probably occurred between 6600 and 9000 BP.

scholarly journals Analysis of Pore Water Pressure and Piping of Hydraulic Well

Water ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 502
Author(s):  
Jinman Kim ◽  
Heuisoo Han ◽  
Yoonhwa Jin
Keyword(s):  
Numerical Analysis ◽  
Water Level ◽  
Pore Water ◽  
Large Scale ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Hydraulic Gradient ◽  
Water Levels ◽  
Seepage Velocity ◽  
Seepage Analysis

This paper shows the results of a field appliance study of the hydraulic well method to prevent embankment piping, which is proposed by the Japanese Matsuyama River National Highway Office. The large-scale embankment experiment and seepage analysis were conducted to examine the hydraulic well. The experimental procedure is focused on the pore water pressure. The water levels of the hydraulic well were compared with pore water pressure data, which were used to look over the seepage variations. Two different types of large-scale experiments were conducted according to the installation points of hydraulic wells. The seepage velocity results by the experiment were almost similar to those of the analyses. Further, the pore water pressure oriented from the water level variations in the hydraulic well showed similar patterns between the experiment and numerical analysis; however, deeper from the surface, the larger pore water pressure of the numerical analysis was calculated compared to the experimental values. In addition, the piping effect according to the water level and location of the hydraulic well was quantitatively examined for an embankment having a piping guide part. As a result of applying the hydraulic well to the point where piping occurred, the hydraulic well with a 1.0 m water level reduced the seepage velocity by up to 86%. This is because the difference in the water level between the riverside and the protected side is reduced, and it resulted in reducing the seepage pressure. As a result of the theoretical and numerical hydraulic gradient analysis according to the change in the water level of the hydraulic well, the hydraulic gradient decreased linearly according to the water level of the hydraulic well. From the results according to the location of the hydraulic well, installation of it at the point where piping occurred was found to be the most effective. A hydraulic well is a good device for preventing the piping of an embankment if it is installed at the piping point and the proper water level of the hydraulic well is applied.

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