AN EVALUATION OF SURFACE HARDNESS OF NATURAL AND MODIFIED ROCKS USING SCHMIDT HAMMER: STUDY FROM NORTHWESTERN HIMALAYA, INDIA

Four rock types (quartz mica gneiss, schist, quartzite and calc-silicate) located in the Satluj and Alaknanda valleys were used to test whether a Schmidt hammer can be used to distinguish rock surfaces affected by various natural and man-induced processes like manual smoothing of rock surfaces by grindstone, surface weathering, deep weathering, fluvial polishing and blasting during road construction. Surfaces polished by fluvial process yielded the highest Schmidt hammer rebound (R-) values and the blast-affected surfaces yielded the lowest R-values for the same rock type. Variations in R-value also reflect the degree of weathering of the rock surfaces. It has been further observed that, for all the rock types, the strength of relationship between R-values for the treated surfaces (manual smoothing of rock surface by grindstone) and the unconfined compressive strength (UCS) is higher than for the fresh natural surfaces.     

西南岩溶山地乡村景观格局与石漠化调控展望

西南岩溶山地乡村景观格局石漠化过程的生态认识落后于生态治理措施。面对国家需求,优化乡村景观格 局对石漠化发生过程的调控,未来优先研究领域：⑴识别岩溶山地乡村景观格局的转换、渐变和基本不变的层次 性,测算不同尺度下乡村景观类型及其空间组合的贡献;⑵认识不同类型乡村景观空间分布的生态学意义及其对 区域石漠化整体程度的影响,找出不同乡村景观演化格局下的石漠化效应;⑶厘定岩溶山地高强度人类活动及其 所诱导的乡村景观格局演化对石漠化的作用效应,构建乡村景观石漠化的成因框架;⑷探讨乡村景观格局制约下 有利于石漠化土地恢复的格局优化模拟,丰富人们对岩溶山地乡村石漠化发生过程的理解和认识。     

Comparative analysis of coatings on granitic substrates from urban and natural settings (NW Spain)

Rock coatings are frequent on natural rock outcrops and even more on stone surfaces of historical buildings and monuments. They are interesting as some of them have a protective effect against erosion. In the last 30 years, research on rock coatings has been performed separately on either buildings or natural outcrops. This paper studies and compares thin coatings found on granitic rock surfaces of historical buildings with coatings found on natural granite outcrops in a same climatic area (NW Spain) by analysing their surface and cross-sections. As rock surfaces of buildings have known age they can be used to assess rates of weathering and coating growth. This is the first comparative study of formation of coatings on natural and built surfaces in the same region. Both endogenous (rock characteristics) and exogenous factors (climatic conditions, air pollution) that could affect the coatings formation are considered to assess the origin and formation of coatings. X-Ray Diffraction (XRD) and X-Ray Fluorescence (XRF) analyses of the underlying rocks, XRD analyses of the coatings and Scanning Electron Microscopy (SEM) observations of surface and cross-sections of the coatings, performing Energy Dispersive Spectrometry (EDS) and X-ray maps, were carried out to establish their composition. Fieldwork and results indicate that natural outcrops are widely covered by biological coatings or coatings formed due to rock weathering, while coatings found on rock ashlars are highly variable with air pollution, other building materials, organic droppings and micro-environmental factors contributing to coatings on rock ashlars in a more significant way than substrate characteristics and exposure time.     

蒙自喀斯特断陷盆地边坡与盆缘的露石差异性

喀斯特露石常常占据一定比例的地表面积,且具有许多已知或未知的水文—生态功能,对于喀斯特地区的植被恢复和环境改善发挥着重要的作用。本实验运用样线法和拍照法识别喀斯特断陷盆地不同位置(盆缘和盆地边坡)露石的数量特征和外部形态特征,同时比较了两种方法测量样地岩石裸露率的精准度。结果发现:盆地边坡与盆缘的露石数量和外部特征存在显著差异,盆缘露石分布密度(0.54个·m-2)>盆地边坡(0.39个·m-2);但盆地边坡露石的长宽比大于盆缘,单体占地面积为盆缘露石的两倍,接近40%的盆地边坡露石与山体等高线平行。样线法和拍照法测量样地岩石裸露率的结果存有差异,但并不显著,且这种差异呈现出随着岩石裸露率的增加而逐渐增加的趋势,拍照测量结果具有较小的变异系数。这些结果说明了研究区露石具有较强的空间异质性,对解释地表水土运移规律和植物分布提供重要参考。拍照法能准确地测量岩石裸露率,并提供露石外部形态特征的精准数据,可以作为喀斯特样地露石调查的新方法加以推广。     

结构面倾角对岩质边坡位移影响的分析

岩体结构面是影响岩质边坡位移及其稳定性的重要因素之一,但是由于数学和力学上的困难,岩体结构面对岩质边坡变形的影响通常难以用理论公式计算得出,目前只能采用数值分析手段。分别针对坚硬岩边坡和软岩边坡中存在软弱结构面的情况,用有限元差分程序FLAC和边坡稳定性系数公式,定量和定性地讨论了岩体结构面倾角对岩质边坡位移的影响。通过计算分析发现,(1)岩体中结构面的存在是影响岩石边坡位移及其稳定性的重要因素之一;(2)随着结构面倾角的增加,边坡的稳定性和边坡的位移可能增加,也可能减小,并不象我们想象的那样随着结构面倾角的增加而增加,必须用定性和定量方法针对具体问题进行具体分析。     

薄盒式光纤岩体裂缝计研究

山体(岩体)破坏和发展过程可以看作为裂纹扩展的过程,可以实现对其发展过程进行实时监测.为此,研究了一种薄盒式光纤岩体裂缝计.给出了其结构设计,并对该薄盒式光纤岩体裂缝计的性能进行了位移和压力两项室内试验研究,结果表明:所研究的光纤岩体裂缝计,具有可靠、实用和高灵敏度等特点,对于山体(岩体)(或其他裂缝工程体,如水坝)的变形发展和失稳的机理研究和早期预报,将是一种良好的传感监测设备,具有较好的工程应用价值.     

Patterns of rock fragment cover generated by tillage erosion

Intensively cultivated areas in the upper part of the Guadalentin catchment (southeast Spain) show a systematic spatial pattern of surface rock fragment cover (R_c). The objective of this paper is to quantify and to explain this spatial rock fragment cover pattern. Therefore, a map of an intensively cultivated area of 5 km² was digitised, and for each pixel total topographic curvature was calculated. Next, rock fragment cover was determined photographically at 35 sites with a range of total slope curvatures. A linear relation between total curvature and rock fragment cover was found, except for narrow concavities. It was hypothesised that this pattern can be explained by a significant net downslope movement of rock fragments and fine earth by tillage. The displacement distances of rock fragments by tillage with a duckfoot chisel were measured by monitoring the displacement of tracers (painted rock fragments and aluminium cubes) on 5 sites having different slopes. The rare of tillage erosion for one tillage pass with a duckfoot chisel, expressed by the diffusion constant (k), equals 282 kg/m for up and downslope tillage and only 139 kg/m for contour tillage. Nomograms indicate that mean denudation rates in almond groves due to tillage erosion (3 to 5 tillage passes per year) can easily amount to 1.5–2.6 mm/year for contour tillage and up to 3.6–5.9 mm/year for up- and downslope tillage for a field, 50 m long and having a slope of 20%. These figures are at least one order of magnitude larger than reported denudation rates caused by water erosion in similar environments. Hence tillage erosion contributes significantly to land degradation. The downslope soil flux induced by tillage not only causes considerable denudation on topographic convexities (hill tops and spurs) and upper field boundaries but also an important sediment accumulation in topographic concavities (hollows and valley bottoms) and at lower field boundaries. Kinetic sieving (i.e. the upward migration of rock fragments) by the tines of the duckfoot chisel also concentrates the largest rock fragments in the topsoil in such a way that a rock fragment mulch develops in narrow valleys and at the foot of the slopes. These results clearly indicate that tillage erosion is the main process responsible for the observed rock fragment cover pattern in the study area. Since the study area is representative for many parts of southern Spain where almond groves have expanded since 1970, the results have a wider application. They show to what extent intensive tillage of steep slopes has contributed to the increase in soil degradation, to changes in hillslope morphology (i.e. strong denudation of convexities, development of lynchets and rapid infilling of narrow valley bottoms) and to the development of rock fragment cover patterns which control the spatial variability of the hydrological and water erosion response within such landscapes.     

Development of tongue-shaped and multilobate rock glaciers in alpine environments – Interpretations from ground penetrating radar surveys

Rock glaciers occur as lobate or tongue-shaped landforms composed of mixtures of poorly sorted, angular to blocky rock debris and ice. These landforms serve as primary sinks for ice and water storage in mountainous areas and represent transitional forms in the debris transport system, accounting for ~ 60% of all mass transport in some alpine regions. Observations of active (flowing) alpine rock glaciers indicate a common association between the debris that originates from cirque headwalls and the depositional lobes that comprise them. The delivery of this debris to the rock glacier is regulated primarily by the rate of headwall erosion and the point of origin of debris along the headwall. These factors control the relative movement of individual depositional lobes as well as the overall rate of propagation of a rock glacier. In recent geophysical studies, a number of alpine rock glaciers on Prins Karls Forland and Nordenskiöldland, Svalbard, Norway, and the San Juan Mountains of southwest Colorado, USA, have been imaged using ground penetrating radar (GPR) to determine if a relationship exists between the internal structure and surface morphology. Results indicate that the overall morphologic expression of alpine rock glaciers is related to lobate deposition during catastrophic episodes of rockfall that originated from associated cirque headwalls. Longitudinal GPR profiles from alpine rock glaciers examined in this study suggests that the difference in gross morphology between the lobate and tongue-shaped rock glaciers can be attributed primarily (but not exclusively) to cirque geometry, frequency and locations of debris discharge within the cirque, and the trend and magnitude of valley gradient in relation to cirque orientation. Collectively, these factors determine the manner in which high magnitude debris discharges, which seem to be the primary mechanism of formation, accumulate to form these rock glaciers.     

Structural control of the morphometry of open rock basins, Kananaskis region, Canadian Rocky Mountains

The morphometry of chutes (couloirs), rock funnels, and open cirques are related to the structure of dissected rock masses in the Kananaskis region of the Canadian Rocky Mountains. Data for ten morphometric variables were derived from digital elevation models of 56 open rock basins. The basins were classified structurally according to the relative orientations of bedding planes and the rock slopes. A hypothesis of no differences in morphometry among structural classes is rejected from the results of nonparametric analysis of variance and paired comparisons of rank scores. Basins on dip and overdip slopes have a distinct size, and those on anaclinal slopes have a distinct width and shape. Variation in morphometry from low compactness and area/relief (chutes) to high compactness and low area/relief (funnels) to high compactness and area/relief (open cirques) corresponds to a change in dominant structure from orthoclinal to dip-overdip to underdip to anaclinal. The dip of bedding planes relative to the slope of rockwalls controls the mode of initial displacement of joint blocks and, thereby, the spatial distribution of the retreat of rockwalls. The angle between the rock slope and the strike of dipping strata determines whether beds of differing stability form chutes and buttresses (orthoclinal slopes), or extend across rockwalls (cataclinal and anaclinal slopes) and retreat at similar rates to form funnels and open cirques. The optimal structure for large compact rock basins is anaclinal, and the least favourable is cataclinal dip-overdip slopes. Topoclimate and other geologic structures may account for variance in morphometry not explained by differences among structural classes.     

Internal Structure and Permafrost Characteristics of the Rock Glaciers of Southern Carpathians (Romania) Assessed by Geoelectrical Soundings and Thermal Monitoring

Six rock glaciers in the Southern Carpathians have been investigated by means of geoelectrical soundings in order to detect their internal stratigraphy and the existence of frozen sediments. In the case of three relict rock glaciers, the electrical resistivity measurements indicated a typical internal structure. Low resistivity values (<10 kΩm) which are typical of unfrozen fine‐grained materials were obtained, but high resistivity values (25–240 kΩm) measured in the Pietroasa, Ie?u and Pietrele rock glaciers denote the presence of sediments cemented by interstitial ice and ice lenses. Based on the moderate resistivity values, the ice content is probably low to medium in the upper portion of these rock glaciers, that is, above 2040 m. At two sites (Pietroasa and V?iuga rock glaciers), ground surface temperature (GST) evolution was monitored using digital dataloggers. Mean annual ground surface temperature and GST regime throughout the winter were extracted from the recordings and confirmed the probability of permafrost occurrence in Pietroasa rock glacier. In the Ie?u and Pietrele rock glaciers, measurements of bottom temperatures of the winter snow cover were performed in March 2012. Considering the thick active layer, the reduced ice content and the presence of scarce vegetation on their surface it could be assumed that the permafrost exists in marginal conditions in the Southern Carpathians. The ground ice in permafrost is produced by the groundwater freezing or by snow banks buried by coarse angular boulders following large rockfalls.     

Photogrammetric Analysis of Front Range Rock Glacier Flow Rates

Flow rates for rock glaciers in the European Alps have been monitored using photogrammetric techniques; however, a program has not been initiated for similar Front Range, USA, rock glaciers. Horizontal rock glacier displacements were measured by tracking large surficial rocks on temporal orthophotos from 1978, 1990, and 1999. Vertical change was measured by creating digital elevation models (DEMs) from digital stereopairs, then subtracting elevations to detect change. Long‐term horizontal velocities ranged from 14 to 20 cm/yr on average, although uncertainty ranged from 4 to 5 cm/yr. On average, vertical elevation changes were negligible with most rock glaciers exhibiting a slight growth or thinning (1–2 cm/yr). Over shorter time scales (c. 10‐year periods), horizontal velocities have only increased by about 2 cm/yr. Because horizontal and vertical change is minimal, Front Range rock glaciers appear to be adjusted with current climate, unlike some rock glaciers in the European Alps that have shown increasing subsidence rates or significant increasing or decreasing horizontal velocities.     

Phosphate rock demand into the next century: Impact on wolld food supply

A vital and indisputable link exists between phosphate rock and world food supply. Phosphate rock is the source of phosphorus used to make phosphatic fertilizers, essential for growing the food needed by humans in the world today and in the future. We modeled the depletion of the known reserves and reserve base (which includes reserves) of phosphate rock based on various scenarios for increasing population and future demand for phosphate. Using these scenarios, the presently known reserves will be depleted within about 50 years, and the remainder of the reserve base will be depleted within the next 100 years. For this model, we used rates of growth of demand for phosphate rock of between 1 and 1.7 percent annually. We also examined demand rates that decrease over time toward demand stasis. Growthrate scenarios that stabilize demand at the year 2100 are little different from unconstrained growth. Demand stabilization by 2025 extends the reserve base by only about 50 years. Additional considerations could affect these depletion scenarios, causing them to be substantially too high or too low. Nonetheless, the incluctable conclusion in a world of continuing phosphate demand is that society, to extend phosphate rock reserves and reserve base beyond the approximate 100 year depletion date, must find additional reserves and/ or reduce the rate of growth of phosphate demand in the future. Society must: 91) increase the efficiency of use of known resources of easily minable phosphate rock; (2) discover new, economically-minable resources; or (3) develop the technology to economically mine the vast but currently uneconomic resources of phosphate rock that exist in the world. Otherwise, the future availability of present-cost phosphate, and the cost or availability of world food will be compromised, perhaps substantially.     

Widespread Occurrence of Ephemeral Funnel Hoarfrost and Related Air Ventilation in Coarse‐Grained Sediments of a Relict Rock Glacier in the Seckauer Tauern Range,Austria

This paper examines the occurrence of ephemeral hoarfrost crystals at funnel openings (funnel hoarfrost) detected between large blocks at the surface of the presumably relict Schöneben Rock Glacier. Field mapping on 25 November 2011 identified 51 individual funnel openings with notable hoarfrost crystals distributed over the entire rock glacier. Hoarfrost was no longer detectable a few days after the initial mapping campaign. At least in the period 20–25 November 2011 temperature conditions at the rock glacier surface were favourable for hoarfrost formation and preservation as indicated by different types of measurements. A period of 24–48 h of hoarfrost‐suitable weather conditions would have been sufficient to form the observed hoarfrost if crystal growth rates of 2–4 mm h^?1 are assumed. The void systems with funnel hoarfrost seem to be rather localised and limited in horizontal (10s of metres) and vertical (some metres) extent. Presumably the observed funnel hoarfrost was caused by the so‐called chimney effect, although no larger reversible air circulation systems with warm air exhalation were identified. Continuous ground temperature data from several sites at the rock glacier surface (period November 2011–December 2012) showed that hoarfrost sites are cooler and thermally buffered compared with non‐hoarfrost sites at similar elevations. This seems to be related to the decoupling of the air above the rock glacier and the pore air during periods of atmospheric warming. Only the combination of specific micro‐climatic (temperature/humidity), geometric (open void systems) and sedimentological (grain size/sediment structure) conditions allow the formation of the ephemeral funnel hoarfrost at this rock glacier.     

Laboratory study of the effect of temperature difference on the disintegration of redbed softrock

To explore the impact of temperature difference (TD) on the disintegration of redbed softrock, three types of redbed rock, collected from Nanxiong Basin, were analyzed under three different treatments: TD, wetting and drying (WD), and TDWD-temperature difference and WD. To better understand the influence of different ranges of TD on disintegration during WD cycles, pH (hydrogen ion concentration) values, electrical conductivity (EC) values, and concentration of cations in leachate released during treatment were measured. The results show that no significant change can be observed under single TD treatment but that TD can increase the disintegration rate by accelerating the water–rock interaction. The effect of TD is more significant for rock with weak resistance to disintegration.     

黄河黑山峡无植被区的地表组成物质遥感信息模型

下垫面物质组成是土壤侵蚀模型最主要的输入参数。应用遥感技术提取无植被地区下垫面物质组成信息对于研究大面积土壤侵蚀是非常重要的。黄河黑山峡地区地形复杂,加之裸土、沙漠和岩石光谱的相似性与复杂性,使遥感技术在该地区的应用受到限制,但是由于地形起伏、岩石风化及表面粗糙度等因素的影响,石质山地纹理明显。综合了光谱和纹理信息特征,本文提出光谱归一化方法,并将归一化的光谱与纹理信息相结合构建了石质山地指数(RMI),应用归一化光谱进一步得到沙漠指数(DI),实现石质山地、沙漠与裸土分离。结果表明,该方法提高了信息提取的精度。     

Dendrogeomorphological assessment of movement at Hilda rock glacier, Banff National Park, Canadian Rocky Mountains

Abstract The results of this dendrogeomorphological study provide evidence of the active movement of Hilda rock glacier, a tongue‐shaped rock glacier in the Columbia Icefield region of Banff National Park. Cross‐sectional samples were cut from 44 detrital subalpine fir (Abies Iasiocarpa (Hook.) Nutt.) and Engelmann spruce (Picea engelmannii Parry) boles killed and buried by debris spilling off the steep distal slope of the 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. Our 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 of the climatic forcing mechanisms known to influence glacier mass balances over the same interval.     

Flow velocities of active rock glaciers in the Austrian Alps

High surface flow velocities of up to 3 m a^–1 were measured near the front of three active rock glaciers in the western Stubai Alps (Rei‐chenkar) and Ötztal Alps (Kaiserberg and Ölgrube) in Tyrol (Austria) using differential GPS technology. Flow velocities have increased since about 1990. The highest velocities were recorded in 2003 and 2004, but showed a slight decrease in 2005. At the Reichenkar rock glacier, flow rates are constant throughout the year, indicating that meltwater has no significant influence on the flow mechanism. At Ölgrube rock glacier, flow velocities vary seasonally with considerably higher velocities during the melt season. Meltwater is likely to influence the flow of Ölgrube rock glacier as evident by several springs near the base of the steep front. Because the high surface velocities cannot be explained by internal deformation alone on Reichenkar rock glacier, we assume that horizontal deformation must also occur along a well defined shear zone within a water‐saturated, fine‐grained layer at the base of the frozen body. The increased surface flow velocities since about 1990 are probably caused by slightly increased ice temperature and greater amounts of meltwater discharge during the summer, a product of global warming.     

砒砂岩区地貌形态三维分形特征量化及空间变异

针对现有地貌形态三维分形模型结构存在的不足,构建一个新的地貌形态三维分形维数测算模型。基于该模型对砒砂岩区274个小流域的地貌形态三维分形维数进行计算并分析其空间变异规律。研究表明：① 基于该模型计算的分形维数能更准确地反映地貌形态复杂度信息;② 砒砂岩区小流域地貌形态三维分形维数介于1.683 6~1.948 6之间;③ 地貌形态三维分形维数整体上覆土砒砂岩区（均值为1.765 9）<裸露砒砂岩强度侵蚀区（均值为1.785 4）和剧烈侵蚀区（均值为1.774 8）<覆沙砒砂岩区（均值为1.796 6）。由于地表覆盖物、砒砂岩裸露程度和土壤侵蚀机理的差异而形成的不同地貌特征是该区地貌形态分形特征空间变异的主要原因。     

Fractal structure of the time distribution of microfracturing in rocks

Using acoustic emission data obtained from laboratory double torsion tests, we have analysed the fractal nature of a series of 29 granite microfracturing processes in time. The data represent a wide variety of timescales, stress environments (increasing load with a constant displacement rate, relaxation, creep), soaking conditions [air, water, dodecyl trimethyl ammonium bromide (DTAB), polyethelene oxide (PEO) ], and material anisotropy. We find that the time distribution of rock microfracturing displays fractal and multifractal properties. In some cases, it has a single fractal or a multifractal structure. In other cases, it changes from a single fractal structure into a multifractal structure as the system evolves dynamically. We suggest that the heterogeneity of the rock, the distribution of joints or weak planes, the stress level, and the nature of the microfracturing mechanism lead to these multifractal properties. Whatever the fractal structure of the system, a lower fractal dimension is generally produced at near-failure of the rock due to an increased clustering. This result concerning the fractal-dimension decrease is consistent with the conclusion drawn from the spatial distribution of rock microfracturing. Therefore, from the vantage point of observation of the time distribution of rock microfracturing, the decrease of the fractal dimension has a potential use as a rock failure predictor.