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Rock resistance to erosion : some further considerations

Rock resistance to erosion : some further considerations
Carbonate rocks ; Erosion ; Geomorphology ; Rock mechanics ; Rocks
Allison (1988, 1990) examined the intact strength properties of several types of carbonate rocks and considered that dynamic Young's modulus is a good indicator of rock material strength for geomorphic purposes, and cast doubts on the reliability.

Rock temperatures as an indicator of weathering processes affecting rock art

Rock temperatures as an indicator of weathering processes affecting rock art
Archaeology ; Index ; Moisture ; Rock ; South Africa ; Temperature ; Thermal regime ; Weathering
, in the study of rock temperature regimes are presented and briefly discussed with respect to rock weathering mechanisms.
To aid rock art conservation, rock temperatures have been monitored at different depths and acquisition rates in a painted rock shelter in the uKhahlamba-Drakensberg Park (South Africa). Preliminary results, records of winter temperatures

Advance mechanisms of rock glaciers

Advance mechanisms of rock glaciers
Alps (The) ; Creep ; Glacier dynamics ; Mountain ; Research technique ; Rock glacier ; Switzerland
In this contribution, an approach to measure mass balance and transport within rock glacier fronts is presented. The technique is applied to Gruben and Suvretta rock glaciers, Swiss Alps. The results confirm a conveyor belt-like advance mechanism

Rock glaciers : II models and mechanisms

Rock glaciers : II models and mechanisms
Classification ; Creep ; Earth surface processes ; Glacier ; Glacier dynamics ; Glaciology ; Ice ; Mountain ; Permafrost ; Rock glacier ; Talus;Slope scree;Slide rocks ; Terminology
This second part of a review deals with the mechanisms of rock glacier formation and flow. The AA. first discuss terminological and classification problems associated with rock glaciers and dynamic nature of rock glaciers. The third part concludes
this series of papers by discussing the role and significance of rock glaciers in mountain geomorphology, glaciology and environmental reconstructions.

Why permafrost rocks become unstable : a rock–ice-mechanical model in time and space

Why permafrost rocks become unstable : a rock–ice-mechanical model in time and space
Climatic warming ; Glacial features ; Ice ; Ice wedges ; Mass movement ; Model ; Mountain ; Paraglacial ; Permafrost ; Rock mechanics ; Slope dynamics ; Space time
Here, the AA. develop a mechanical model that relates the destabilization of thawing permafrost rock slopes to temperature-related effects on both, rock- and ice-mechanics; and laboratory testing of key assumptions is performed. The destabilization
and detachment mechanisms along rock-ice interfaces. Novel laboratory setups were developed to assess the temperature dependency of the friction of ice-free rock-rock interfaces and the shear detachment of rock-ice interfaces. The model explains why all
is commonly attributed to changes in ice-mechanical properties while bedrock friction and fracture propagation have not been considered yet. However, fracture toughness, compressive and tensile strength decrease by up to 50% and more when intact water
-saturated rock thaws. Based on literature and experiments, the AA. develop a modified Mohr-Coulomb failure criterion for ice-filled rock fractures that incorporates fracturing of rock bridges, friction of rough fracture surfaces, ductile creep of ice
magnitudes of rock–slope failures can be prepared and triggered by permafrost degradation and is capable of conditioning long para-glacial response times.

Rates of rock property changes with weathering : andesite gravel in fluvial terrace deposits in Nasuno-ga-hara, Japan

Rates of rock property changes with weathering : andesite gravel in fluvial terrace deposits in Nasuno-ga-hara, Japan
Erosion rate ; Fluvial terrace ; Honshu ; Igneous rock ; Japan ; Mineralogy ; Porosity ; Rock ; Rock mechanics ; Weathering
and mechanical properties as well as apparent thickness of brown layers were investigated. The results indicate that mechanical properties change more rapidly than other properties.

Frost bursting : a violent expression of frost action in rock

Frost bursting : a violent expression of frost action in rock
The purpose of this paper is to substantiate an explosive origin for some rock breakdown by identifying the pertinent environmental conditions and mechanical properties of the rock in which it occurs.

Mechanism of failure and slope development in rock masses

Mechanism of failure and slope development in rock masses
Cliff ; England ; Geotechnics ; Island ; Limestone ; Mass movement ; Model ; Rock mechanics ; Slope ; Slope gradient ; United Kingdom
This paper examines the mechanisms of failure in jointed rock slopes. The Universal Distinct Element Code (UDEC) has been employed in this study to examine associations between rock-mass geotechnical properties, the processes operating at and close
to the surface of the Earth, slope morphology and development. Particular attention has been paid to the control of the geometrical distribution of discontinuities in a rock mass and the factors that delimit particular types of failure, such as topples and slides
. After a theoretical modelling exercise, real-world rock slopes were studied from the Portland Limestone outcrop of the Isle of Purbeck, England.

Microstructural influence on strength reduction of porous rhyolite during weathering

Chemical erosion ; Geochemistry ; Island ; Japan ; Microstructure ; Mineralogy ; Porosity ; Rock ; Rock mechanics ; Volcanic rock ; Weathering
To examine the mechanism of rock-strength reduction due to weathering, temporal changes in microstructure of 4 porous rhyolite were investigated at Kozu-shima Island in the western Pacific. With the results of mineralogical investigations
and laboratory tests of pore structure of the rocks, the AA. conclude that the microstructural changes due to chemical weathering strongly influence the reduction of rock strengths.

Rates and mechanisms of change in hard rock coastal cliffs in Coasts : erosion and sedimentation.

Rates and mechanisms of change in hard rock coastal cliffs in Coasts : erosion and sedimentation.
discontinuity pattern. Emphasis is thus placed on the synthesis of quantifiable rock mechanics parameters and details of change in coastline morphology. Results indicate that although cliff retreat shows no regular spatial or temporal pattern, clear trends can
Investigations have concentrated on the Jurassic Portland Limestone outcrop of the Isle of Purbeck. Three types of data are considered, including mapped changes in the nature and location of the cliffline, material strength and the rock mass

Modelling failure mechanisms to explain rock slope change along the Isle of Purbeck coast, UK

Modelling failure mechanisms to explain rock slope change along the Isle of Purbeck coast, UK
Carbonate rock ; Cliff ; Coastal environment ; Dorset ; England ; Limestone ; Mass movement ; Model ; Rock mechanics ; Slope dynamics ; Slope gradient ; United Kingdom
Results are presented of distinct element computer modelling used to examine rates and mechanisms of change in rock slopes and cliffs, where material intact properties determine process and form but the most significant controls are the joint
pattern and cross-joint properties. Field and laboratory data have been collected for the Portland Limestone outcrop of the Isle of Purbeck, central southern England. There are resulting implications for spatial variations in rock slope evolution.

Daytime rock surface temperature variability and its implications for mechanical rock weathering : Tenerife, Canary islands

Daytime rock surface temperature variability and its implications for mechanical rock weathering : Tenerife, Canary islands
Rock surface temperature measurements are presented from three sites on the arid to semi-arid southern slopes of Tenerife. The sites were selected to represent a climatic gradient from sea-level to high altitude and measurements were collected under

The mechanical behaviour of rock under crustal and mantle conditions in The Earth: its origin, structure and evolution.

The mechanical behaviour of rock under crustal and mantle conditions in The Earth: its origin, structure and evolution.
A brief survey is given of the types of mechanical behaviour that might be expected in the crust and mantle in the light of recent experimental studies. Emphasis is placed on the variety of possible behaviour and the difficulties that arise out
of this variety in making relevant extrapolations from the time scale of experiments to that of natural deformations. The particular case of olivine-rich rocks, of interest in mantle studies, is taken up in more detail, with a critical survey of available

Caratterizzazione sperimentale e analitica del comportamento viscoplastico di una calcarenite porosa

Building materials ; Carbonate rock ; Chalk ; Experimentation ; Geotechnics ; Italy ; Puglia ; Rock mechanics
in the Salento area, since the renaissance and baroque age. Such rock has been already used for other studies concerning well-bore stability, damage mechanics and compaction problems of oil reservoirs. - (NF)
This work presents results on the mechanical behaviour of an outcrop Miocene porous chalk, named Pietra Leccese, in a general elasto-viscoplastic field. The Pietra Leccese limestone has been of great importance as construction material

Analysis of crack movements observed in an alpine bedrock cliff

Fracture ; Freezing ; Hokkaido ; Ice wedge ; Japan ; Mountain ; Rock mechanics ; Rockfall ; Temperature ; Thermal regime
in catastrophic rock breakage. Using these sequential data, the timing, magnitude, and dominant agent of crack movement are considered, with particular focus on the parameters related to rock fracture mechanics.
Crack widths and rock temperatures were monitored on an andesitic bedrock cliff in the summit area of the Daisetsu Mountains, Hokkaido. Sequential data recorded the gradual widening of a crack to the point of critical crack extension, which resulted

Rock moisture content in the field and the laboratory and its relationship to mechanical weathering studies

Rock moisture content in the field and the laboratory and its relationship to mechanical weathering studies

Frost action and hydration as rock weathering mechanisms on schist: a laboratory study

Frost action and hydration as rock weathering mechanisms on schist: a laboratory study
not as effective as frost action in causing particle size reduction in aggregates, the two mechanisms may well reinforce one another in periglacial environments, enhancing the ability of these areas to serve as source regions for loess.

The influence of two epilithic lichens on the weathering of quartzite and gabbro

Biogenic action;Biogenic process ; Crystalline rocks ; Vegetation ; Weathering
Evidence is presented suggesting that micro-vegetation, notably lichens, substantially influences the weathering of the material on which it grows. Changes on two rock types are examined in order to assess the role of lichens in the mechanical

A review of rockfall mechanics and modelling approaches

A review of rockfall mechanics and modelling approaches
Bibliography ; Comparative study ; Geographical information system ; Model ; Natural hazards ; Rock mechanics ; Rockfall ; Slope ; Slope dynamics
This study summarizes existing rockfall models and proposes modifications to make them suitable for predicting rockfall at a regional scale. First, the basic mechanics of rockfall are summarized. Secondly, existing models are divided in 3 groups

Debris-covered glaciers and rock glaciers in the Nanga Parbat Himalaya, Pakistan

Debris-covered glaciers and rock glaciers in the Nanga Parbat Himalaya, Pakistan
Glacier ; Glacier dynamics ; High mountain ; Himalaya ; Meltwater ; Pakistan ; Remote sensing ; Rock glacier
The origin and mobilization of the extensive debris cover associated with the glaciers of the Nanga Parbat Himalaya is complex. The AA. propose a mechanism by which glaciers can form rock glaciers through inefficiency of sediment transfer from
glacier ice to meltwater. They document with maps, satellite images, and field observations the probable evolution of part of a slow and inefficient glacier into a rock glacier at the margins of Sachen Glacier in c. 50 years, as well as several other

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