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
The sediments of a large accumulation landform, interpreted as one of 6 Pleistocene rock glaciers occurring in the Ślęża Massif, are described. The sediments have been subject to strong compression and the main deformation mechanism
is that of shearing. It is inferred that ice was necessary for the debris transport. Because the geomorphological setting excludes a glacigenic origin, the sediments are interpreted to result from the creep of permafrost, i.e. the landform is a relict rock glacier.
Effect of rock fragment eccentricity on eolian deposition of atmospheric dust
The aim of this study is to investigate the physical effects of rock fragment eccentricity on the dust deposition mechanism. This was examined in a wind tunnel. All data in this study refer to intial dust deposition (not accumulation), since only
Beach-rock development is based on successive stages of microbial activity, crystal growth, mechanical and biological erosion, etc. The combined study of such events could be a helpful way to recognize and differentiate shoreline variations.
Intrusion of mafic magmas into felsic magma chambers : new insights form natural outcrops and fluid-mechanics experiments
Fractals ; Geology ; Geophysics ; Igneous rock ; Magma ; Rheology ; Rock
ratio between magmas towards low values and, hence, towards the best rheological conditions to trigger widespread mixing processes in the magma chamber. In conclusion, the present paper shows that combining fractal geometry measurements on natural rocks
and fluid-mechanics experiments may help to shed new light into geological processes whose knowledge may open new frontiers in the study of igneus systems and their evolution in time and space. - (NF)
Carbonate rock ; Chemical erosion ; Climate ; Comparative study ; England ; Erosion ; Geomorphology ; Inverted relief ; Ireland ; Isostasy ; Somerset ; United Kingdom ; Weathering
Denudation mechanisms differ fundamentally between limestone and silicate rock types, which are subject to very different rate thresholds and enhancers/inhibitors. Denudation of limestone and of silicates cannot be encompassed by simple models
of differential mechanical erosion of hard and soft rocks. The mechanisms involved, and the factors which influence them, are so fundamentally different that the denudation of these 2 main lithologies must be considered separately before the results are combined
the corresponding process mechanism are discussed. Particular attention is paid to the effects of rock fragment cover on the intensity of soil erosion processes. The scatter of the data indicates that a given rock fragment cover can have different efficiencies
This paper reviews the various effects of rock fragments on soil erosion by water. Since these effects are scale dependent, they are investigated at three different nested spatial scales: the micro-, the meso- and the macroplot. For each scale
Terrain analysis of the Racetrack basin and the sliding rocks of Death Valley
Arid area ; California ; El Niño ; Geographical information system ; Geomorphometry ; Quaternary ; Slide rocks ; United States of America ; Wind speed ; Years 1990-99
The Racetrack Playa's unusual surface features known as sliding rocks have been the subject of an ongoing debate and several mapping projects for half a century, although the causative mechanism remains unresolved. In 1996, the AA. generated
the first complete map of all observed sliding rock trails by submeter differential Global Positioning System (DGPS) mapping technology. Follow-up surveys in 1998 and 1999 revealed little modification of the 1996 sliding rock configuration. Only 4 rocks were
Conference on the last deglaciation: timing and mechanism
at about 10,000-7000 yr ago and (2) the most likely feedback mechanisms for accelerating the initial forcing by orbital variations are delayed bed rock rebound, marine downdraw/calving, and CO heating.
. It considers mainly the geometric characteristics of the faults and dykes themselves, and also explores the effects of mechanical layering on the structure and development of faults and dykes. The focus is on the attitude of dykes and faults, fault displacement
Structural tectonic working methods as used in the foundation rock and in the rockmechanics can be applied to the survey, documentation and interpretation of glacigenous deformations. Introducingly, experience in the finding-out of the pebbles
Dendrogeomorphological assessment of movement at Hilda rock glacier, Banff National Park, Canadian Rocky Mountains
Canada ; Climatic variation ; Dendrochronology ; Glacier advance ; Mountain ; Periglacial features ; Rock glacier ; Rocky Mountains ; Tree line
The results of this dendrogeomorphological study provide evidence of the active movement of Hilda rock glacier. The samples were crossdated using locally and regionally developed tree-ring chronologies, and were shown to have been killed between
1576 and 1999. The results show that Hilda rock glacier has advanced at an average rate of 1.6 cm/year since the late 1790s, with limited evidence of similar rates of activity extending back to the mid-1570s. This rock glacier activity is believed
to be linked to persistent periglacial processes that appear to be independent to the climatic forcing mechanisms known to influence glacier mass balances over the same interval.
Observations from Taylor Valley suggest that the wedging effect of sand particles, packed by powerful winds into cracks in rocks, may act as a weathering mechanism. Discussion.
Pore properties as indicators of breakdown mechanisms in experimentally weathered limestones
Carbonate rock ; England ; Experimentation ; Fracture ; Freeze-thaw cycle ; Limestone ; Microstructure ; Moisture ; Porosity ; Salt ; United Kingdom ; Weathering
rock deterioration mechanisms taking place. It is concluded that the 5 limestones not only show a wide range of resistance to weathering in general but considerable difference in resistance to particular weathering processes.
Chemical erosion ; Electron microscope ; Eruptive rock ; Geochemistry ; Japan ; Lithology ; Mineralogy ; Shikoku ; Weathering
In order to clarify the formative processes of weathering rinds, the AA. accumulate the data on changing in rock properties, such as mineralogical, mechanical, chemical and physical properties through fresh zone to weathering rind. From this point
of view, this paper examines the relationships between rock properties of weathering rinds using sanukitoid-andesite as an example.
Progressive failure of sheeted rock slopes : the 2009–2010 Rhombus Wall rock falls in Yosemite Valley, California, USA
California ; Cliff ; Fracture ; Granite ; LiDAR ; Remote sensing ; Rockmechanics ; Rockfall ; Slope ; Slope dynamics ; United States of America
The AA. present high-resolution photography, video, and laser scanning data that document spatial and temporal patterns of a 15-month-long sequence of at least 14 rock falls from the Rhombus Wall, a sheeted granitic cliff in Yosemite Valley
, California. They suggest that these progressive failures might have been related to stress redistributions accompanying propagation of sheeting joints behind the cliff face. Mechanical analyses indicate that tensile stresses should occur perpendicular
behind cliff faces. They posit that as a region of failure spreads across a cliff face, stress concentrations along its margin will spread with it, promoting further crack propagation and rock falls.
Geotechnical properties of rock masses : their control on slope form and mechanisms of change along the Napier Range, Western Australia
The results presented here highlight the importance of synthesising standard geomorphological site investigation techniques with quantifiable rock geotechnical parameters, in order to understand slope form and development. Field research has been