News from the western front: occurrence of Mediterranea depressa (Sterki, 1880) (Mollusca: Gastropoda: Oxychilidae) in the Vosges and Jura Mountains (north-eastern France)

We report here the first record of Mediterranea depressa (Sterki, 1880) in the north-eastern quarter of France, in the Vosges and Jura massifs. After the fortuitous discovery of some shells attributed to M. depressa in the southern Vosges Mts., an extensive sampling campaign was carried out both in the Vosges and in the Jura Mts. In total, about 20 shells and seven live specimens were found at eight localities, which, according to the present state of our knowledge, represent its north-western range limit. The species was found exclusively under stones of rocky slope screes on siliceous and calcareous substrates. Some of these habitats could be described as Mesovoid Shallow Substratum. It is not clear whether the rarity of the species is an effect of under-sampling or of its small size and unusual habitat or/and to intrinsic rarity due to isolated populations at the distribution limits of the species. The extreme north-eastern quarter of France constitutes an oceanic-continental transition zone where about thirty gastropod species from Central and Eastern Europe are currently documented at the western limit of their ranges.

Study on the Catastrophic Evolution of Tianshan Road Slope under the Freeze-Thaw Cycles

The maximum temperature difference of Tianshan Road can reach 77.4°C in a year. Under such complex mechanical environment, the mechanical properties of rock mass and structural planes will change significantly as the increase of freeze-thaw cycles (FTC). Consequently, the FTC has become a key factor in the instability and failure of rocky slopes along the Tianshan Road. In this paper, the progressive deformation of rocky slopes and sudden failure process after critical instability were studied through the FTC tests of rock mass and structural planes, discrete element method, and theoretical analysis. The results show that the structural planes and internal microcracks of the rock mass expand under the action of the FTC, causing a gradual decrease in the stability of the slope. The dynamic collapse of the rocky slope has a certain degree of randomness caused by the spatial distribution of structural planes and the interaction between the rock fragments. Due to the limitation of the slipping space and the tilt angle of the trailing edge of the slope, long-distance migration did not occur, and the in situ accumulation of the slope was obvious after failure. The analysis method in this paper can provide an important reference for guiding the catastrophe mechanism analysis and protection of engineering slopes in cold regions.

New location of Tulipa mongolica and its phytocenotic confinement in the Trans-Baikal Territory

The article reports on the new location of a rare, narrow-localized miocene-pliocene relic Tulipa mongolicaY. Z. Zhao, in the Trans-Baikal Territory along the south-eastern sandy-rocky slope of the lake Bayn-Tsagan terrace (Ononsky district), as part of the karaganovo-chiovo-vostretsovaya steppe. In the Trans-Baikal Territory, the tulip grows onthe northern border of its range: in the vicinity of the village Budulan, near the town Malyi Bator (Aginsky district) in thebushyed cold-wormwood-kovylnaya steppe; along the northern coast of the lake Zun-Torey, in the village Kulusutai, nearthe town Gydyrgun (Ononsky district) in the karayganovo-raznotravno-kovylnaya steppe. This cenopopulation is locatedon the territory of the protected zone of the Daursky Nature Reserve.

Identification of potential rockfall sources using UAV-derived point cloud

Recent advances in remote sensing techniques and computer algorithms allow accurate, abundant, and high-resolution geometric information retrieval for rock mass characterization from 3D point clouds. The automatic application of the extracted information for local scale rockfall susceptibility assessment, where discontinuities characteristics play a major role in rocky slope stability, requires step by step logical procedures. This paper presents a novel methodology to use the extracted discontinuity set characteristics for a local scale rockfall susceptibility assessment, tailored for Uncrewed Aerial Vehicle (UAV) data acquisition. The method consists of 4 steps: (i) 3D slope model reconstruction using UAV digital photogrammetry, (ii) automatic characterization of discontinuity sets, (iii) slope stability analysis, and (iv) susceptibility assessment using a new Rockfall Susceptibility Index. The proposed method was applied to a road cut rocky slope in a mountainous area of the Samaria National Park, in Crete Island, Greece. Visual validation indicates that the areas of higher and moderate rockfall susceptibility on the 3D model of the rocky slope are adjacent to rockfall source areas marked by the presence of fallen blocks on the foot of the slope. The proposed methodological workflow presents novelties related to the use of point clouds for the estimation of the Rock Quality Designation (RQD) index, the visualization of discontinuity set spacing, the evaluation of the persistence and the Slope Mass Rating (SMR) index, as well as the incorporation of the persistence of overhangs into the rockfall susceptibility assessment and visualization.

The Rise And Fall Of An Oyster Bed In The German Bight (North Sea) Before The Dawn Of Industrial Fishery

<p>The European flat oyster (<em>Ostrea edulis</em>, EFO) has been common in the North Sea at least throughout the late Holocene. Aside from its important ecological function as a reef builder the EFO has been of high economic value ever since man invented commercial fishery. During first half of the 20th century CE the EFO became functionally extinct in the German Bight. It is commonly agreed that industry-style overexploitation using dredges and trawls destroyed the habitats and eventually caused the extirpation of the EFO. Today, the EFO is a severely endangered and protected species.</p><p>Recently, an as yet uncharted fossil EFO bed was encountered close to the island Helgoland (German Bight, SE North Sea), that does not reveal any obvious signs of the physical disturbances typical for heavily harvested sites. This suggests possible environmental forcing behind the decline of this particular EFO bed, which could also have contributed to the fall of the entire oyster population of the German Bight.</p><p>The area was surveyed using drift videos along with grab samples to locate the EFO bed, measure its perimeter and evaluate characteristics, such as the density of shells. A total of 590 shells from 17 locations were measured (length, width) and weighed. A total of 19 shell samples from 17 locations were AMS radiocarbon dated to obtain absolute age control.</p><p>The EFO bed is located on a rocky slope to the west of Helgoland, its area is about 0.6 km<sup>2</sup> and the water depth ranges between 32 and 43 m. The shallower parts are characterized by rubble whereas the EFO bed disappears under muddy sediments in the deeper parts. A rough estimation reveals around 200,000,000 single oyster shells in this bed. The oldest shell dated to about 4000 years BP, the youngest age dates to the beginning of the 19th century CE. Most shell ages are between 2700 and 2000 years BP. A hiatus occurs between 1300 and 300 years BP, and only one measurement reveals an age younger than 1300 years.</p><p>This EFO bed had perished already 1300 years ago, hence intense fishery as a reason can be ruled out. Today, the deeper part of the EFO bed is affected by muddy sediment that temporally buries the seafloor and occasionally forms turbid clouds of suspended matter. The sediment likely originates from large rivers (e.g. Rhine, Weser, Elbe) and the mudflats of the Wadden Sea. Climatic/oceanographic fluctuations that had modified the discharge and transport of muddy sediments in combination with increased influx of sediment from fluvial sources as a result of land-use changes in early medieval central Europe may have been a major stressor for the oyster habitats, albeit biological stressors cannot be ruled out.</p>

Análisis de Estabilidad Probabilístico del Talud de la Cantera Espinal – Juliaca

Análisis de Estabilidad Probabilístico del Talud de la Cantera Espinal – Juliaca Probabilistic Analysis of Slope Stability Espinal Quarry - Juliaca Fredy Alonso Valeriano Nina Facultad de Ingeniería de Minas, Universidad Nacional del Altiplano – Puno – Perú DOI: https://doi.org/10.33017/RevECIPeru2014.0006/ Resumen El presente estudio fue realizado en la cantera Espinal de la ciudad de Juliaca en el departamento de Puno, consiste en determinar los valores de seguridad que rigen la estabilidad o inestabilidad en un talud rocoso; factor de seguridad (FS) o reducción de la resistencia al corte (SRF) y la probabilidad de falla (PF), para lo cual se han utilizado los métodos generales de análisis de estabilidad de taludes en roca; Análisis cinemático y métodos numéricos. Se realizó análisis probabilísticos por el método de estimación de puntos para mayor confiabilidad de los resultados de análisis con métodos numéricos. Teniendo como resultados en el análisis cinemático una probabilidad de plano de deslizamiento por volteo directo de 44.41%, los valores de seguridad promedio dado por los análisis probabilísticos con métodos numéricos en SRF son; para condiciones estáticas FS o SRF 2.27 y PF 0.0% y para condiciones seudoestáticas FS o SRF 1.21 y PF 2.98%. Por lo cual concluimos que el talud se encuentra estable en condiciones estáticas y seudoestáticas, tomando en consideración el resultado del análisis cinemático realizado se han observado grietas de tracción en la cresta del talud que fallaran por volteo directo dependiendo a la intensidad de los factores desencadenantes. Descriptores: Macizo rocosos, análisis probabilístico, factor de seguridad (FS), reducción de la resistencia al corte (SRF), probabilidad de falla (PF). Abstract This study was carried out in the Espinal highway of Juliaca city in the state of Puno, which consists in to determinate the safety values that controls the stability or instability of a rocky slope; safety factor (FS) or shear strength reduction (SRF) and failure probability (PF). Due to this, general methods of rock slope stability were used; cinematic analysis and numerical methods. Probabilistic analyses were conducted by the method of points’ estimation for more reliability in the results of numerical methods. Having in the cinematic analysis results a probability of glide plane by direct toppling of 44.41%, the values of average safety obtained by the probabilistic analysis with numerical methods in SFR are; for static conditions FS or SRF 2.27 and PF 0.0% and for pseudostatical conditions a FS or SRF 1.21 and PF 2.98%. Due to this, we concluded that the slope is stable in static and pseudostatic conditions, considering the results of cinematic analysis, were observed tension cracks on the top of the slope which failed by direct toppling depending of the intensity of trigger factors. Keywords: Rock Mass, probabilistic analysis, safety factor (FS), stress reduction factor (SRF), failure probability (PF).