Rock Block Slide Research Articles

Vegetation Diversity of Screes and Taluses of The Pamir and South-Western Tian Shan in Middle Asia

This paper presents the results of phytosociological research on scree vegetation of the Pamir and south-western Tian Shan. We collected 222 phytosociological relevés during field studies conducted in 2015–2019, applying the Braun-Blanquet approach. We identified 21 plant communities on mobile and stabilized screes of colluvial cones, aprons and fans, inhabiting mainly the montane and alpine belts in several ranges (e.g. Peter the First, Alichur, Shugnan, Shachdarian, Darvaz, Rushan, Vanch, Fergana, Kyrgyz and Terskey ranges). As a result we provide the first comprehensive hierarchical syntaxonomic synopsis of scree communities at montane and alpine elevations in the eastern Middle Asia. The collected vegetation relevés represent the majority of the variation among the phytocoenoses of gravel, pebble, cobble and rock block slides and screes in the montane and alpine belts. As a result of field studies and Twinspan analyses, nine associations were identified on screes of the Pamir and western Tian Shan. All these communities were assigned to the Sileno brahuicae-Lactucetalia orientalis Nowak et al. 2021. Additionally, within the nitrophilous compact gravel screes one subassociation of Corydalidetum kashgaricae trigonelletosum gontscharovii was distinguished. In the most arid zone two additional plant associations and one subassociation were identified in gravelly semi-deserts zone. The main factors determining the species composition of the studied associations are scree mobility, rock particle size, elevation above sea level and slope inclination. Our research revealed considerable diversity of scree habitats of montane and alpine belts what might be astonishing regarding harsh environment of this mountainous territory. However, a great number of lineages that evolved here and particularly rich species pool of this habitat in Middle Asia facilitate remarkable diversity among vegetation of taluses and screes. The distinctiveness of species composition is additionally enhanced by high degree of endemism of chasmophytic habitats in the eastern part of Middle Asia. Despite recent developments, the prominent chasmophytic vegetation of Middle Asia still needs thorough studies focused on its relationship to semi-desert, tall-forb and petrophytic communities of high mountains of the Pamir, Hindu-Kush, Kunlun and Central Tian Shan.

DEM simulation of planar sliding using a particulate interface model considering velocity-dependent friction

Planar sliding is a typical failure mode of landslides, in which an unstable rock block slides along a weak plane, resulting in a rapid movement. This study proposes a particulate interface model (PIM) that considers velocity-dependent friction behavior to simulate the planar sliding behavior of the particulate DEM. To validate the performance of the proposed model, the results of a DEM simulation of the planar sliding of a rigid block are compared with the analytical dynamic solution. The results reveal that the PIM simulation is consistent with the analytical dynamic solution with or without consideration of the velocity-dependent friction law. The ordinary contact model does not accurately reflect the theoretical dynamics owing to the high resistance. The smooth-joint model underestimated the shear resisting force of the interface and yielded excessively high velocity and displacement of the block. With respect to the deposition distribution, the different interface models yielded the various velocities before impact, and therefore various failure patterns of the block and appearances of the deposition. The block velocity significantly influences the number of cracks. The results of the analysis reveal that the PIM can capture the planar sliding and deposition behavior of particulate DEM.

Landslides caused by the Mw7.8 Kaikōura earthquake and the immediate response

Tens of thousands of landslides were generated over 10,000 km2 of North Canterbury and Marlborough as a consequence of the 14 November 2016, Mw7.8 Kaikōura Earthquake. The most intense landslide damage was concentrated in 3500 km2 around the areas of fault rupture. Given the sparsely populated area affected by landslides, only a few homes were impacted and there were no recorded deaths due to landslides. Landslides caused major disruption with all road and rail links with Kaikōura being severed. The landslides affecting State Highway 1 (the main road link in the South Island of New Zealand) and the South Island main trunk railway extended from Ward in Marlborough all the way to the south of Oaro in North Canterbury.
 The majority of landslides occurred in two geological and geotechnically distinct materials reflective of the dominant rock types in the affected area. In the Neogene sedimentary rocks (sandstones, limestones and siltstones) of the Hurunui District, North Canterbury and around Cape Campbell in Marlborough, first-time and reactivated rock-slides and rock-block slides were the dominant landslide type. These rocks also tend to have rock material strength values in the range of 5-20 MPa. In the Torlesse ‘basement’ rocks (greywacke sandstones and argillite) of the Kaikōura Ranges, first-time rock and debris avalanches were the dominant landslide type. These rocks tend to have material strength values in the range of 20-50 MPa.
 A feature of this earthquake is the large number (more than 200) of valley blocking landslides it generated. This was partly due to the steep and confined slopes in the area and the widely distributed strong ground shaking. The largest landslide dam has an approximate volume of 12(±2) M m3 and the debris from this travelled about 2.7 km2 downslope where it formed a dam blocking the Hapuku River. The long-term stability of cracked slopes and landslide dams from future strong earthquakes and large rainstorms are an ongoing concern to central and local government agencies responsible for rebuilding homes and infrastructure. A particular concern is the potential for debris floods to affect downstream assets and infrastructure should some of the landslide dams breach catastrophically.
 At least twenty-one faults ruptured to the ground surface or sea floor, with these surface ruptures extending from the Emu Plain in North Canterbury to offshore of Cape Campbell in Marlborough. The mapped landslide distribution reflects the complexity of the earthquake rupture. Landslides are distributed across a broad area of intense ground shaking reflective of the elongate area affected by fault rupture, and are not clustered around the earthquake epicentre. The largest landslides triggered by the earthquake are located either on or adjacent to faults that ruptured to the ground surface. Surface faults may provide a plane of weakness or hydrological discontinuity and adversely oriented surface faults may be indicative of the location of future large landslides. Their location appears to have a strong structural geological control. Initial results from our landslide investigations suggest predictive models relying only on ground-shaking estimates underestimate the number and size of the largest landslides that occurred.

The Sant'Andrea-Molinello landslide system (Mt. Pruno, Roscigno, Italy

This paper illustrates the landslide processes that affect the southern hillslope of Mt. Pruno in the Sant'Andrea-Molinello area close to Roscigno village (Cilento, Vallo di Diano and Alburni Geopark, Campania region, Italy). The area involved by the slope instability is about 0,7-1 km2 extended and it includes the provincial road no. 342 between the Roscigno and Corleto Monforte villages and other rural roads and farms. The landslide occurred and evolved during the first week of December 2010, as a consequence of the intense rainfalls fallen during the previous month. A detailed field survey highlighted that the 2010 event was only a partial reactivation of a larger landslide system with a very complex structure and long-term evolution.Peculiar geological and hydrogeological conditions control the general instability. The structural setting of the slope is made by the tectonic overlapping of two different structurally complex formations: the Torrente Trenico Marls and Calcarenites Fm. (B1/B2 class), constituting the local upper aquifer, over the Argille Varicolori Superiori Fm. (B2/B3 class), sheared marly clays, as basal aquitard. The primary gravitational event, classified as multiple rock block slide, was probably induced by rapid, local relief creation during the Late Pleistocene, following the downstream Sammaro River's gorge incision. During Holocene and historical times, secondary landslide phenomena, triggered by an increased water pressure within perched layers, affected and progressively disarticulated the primary one by rock slide complexes evolving in complex earth slide-flows.Based on the above geomorphological model and original geotechnical data, stability analyses were carried out in the northern portion of the landslide area. The safety factors, evaluated under different recharge conditions and the sensitivity analysis to pore water pressure confirm the hypothesis of rainfall-induced, partial reactivation with an about 50-years return time.

Hydrogeological monitoring and modelling in the S. Lorenzo road tunnel area (Passo della Morte, Udine) for the design of countermeasure works

In the eastern Italian Alps, a large deep-seated rock block slide affects the S. Lorenzo road tunnel (46°23'49 N, 12°42'51 E) along the National Road 52 Carnica, near to Passo della Morte (Udine Province); the tunnel was excavated through a fractured carbonatic rock mass overthrusted on clay-rich units. Previous studies of the unstable slope outlined the relationship between slope displacements and groundwater flow in the fractured rock mass. The conceptual geological model of the area, together with field observations, allowed specific investigation and monitoring activities to be defined in order to investigate this relationship. In particular, during the last years, six weirs were built and pressure transducers were installed in order to assess the total water discharge from the area. Moreover, 14 piezometers were drilled outside and inside the tunnel to monitor the hydraulic head. After 15 years of monitoring the groundwater system can be described in detail. In particular, results show a double flow system. The first is almost constant for all the year, while the second is influenced by rainfall events and is hosted in faults, fractures and joints in the western part of the tunnel, in the area of the larger and deep-seated rock slide. A three-dimensional groundwater flow model was built and calibrated along the total outflow from the road tunnel in order to better understand the interactions between groundwater flow and road infrastructure. In particular, the effects of countermeasures works, like the extension of the drainage adit in the carbonatic rock mass, was tested.

The Friulian-Venetian Basin I: architecture and sediment flux into a shared foreland basin

In the northern Italian Alps, along the Tagliamento River valley (46°23'49 N, 12°42'51 E), a large deep-seated landslide affects a road tunnel near Passo della Morte, along National Road 52 Carnica. Several secondary phenomena are developing on the unstable slope, as rock block slides and shallow debris slides. This work focuses on the creation of a geological and numerical model able to simulate the displacements of two adjacent and partly superimposed shallow landslides, which are damaging the east entrance of the tunnel. In fact, field surveys and long-term monitoring allowed the geometries and the kinematics of the landslide bodies to be defined with great detail. In this phase, a numerical model is needed in order to evaluate the effectiveness of possible structural mitigation works. The complexity of the landslides dynamics and the different rates of activity suggest to set up a 3D model rather than a 2D one, using the commercial software FLAC3D. A helicopter-borne Light Detection And Ranging (LiDAR) survey allowed to rely on a 1 m Digital Terrain Model (DTM) for surface topography, while several boreholes equipped with inclinometers supported the definition of a 3D sliding surface. However, the high resolution of the input data collides with the necessity of reduce computational time to an acceptable level, thus an interpolation of the spatial data was almost compulsory. Anyhow, the calibrated model of the Passo della Morte landslides, obtained with filtered data, is the starting point for the simulation of different types of possible countermeasure works designed to mitigate landslide risk.

Evaluation of earthquake-induced landslides hazard zonation methods: a case study of Sarein, Iran, earthquake (1997)

Landslides, in general, and seismic landslides, specifically, are among the phenomena that caused a huge loss to the humans over the past years. In this research, one of the novel methods for seismic landslides hazard zonation, a comprehensive areal model of earthquake-induced landslides (CAMEL), is applied to predict the concentration and hazard induced by the landslides and evaluate these landslides by the quantitative approaches. In this regard, the zone affected by the M w = 6.1 Sarein earthquake (1997) was selected as the model area. At first, the necessary information including disturbance distance (distance from river and road), ground strength class, ground moisture, shaking intensity, slope angle, slope height, soil depth, terrain roughness, material type, and vegetation were collected using aerial photos, Landsat satellite images, geological and topographic maps, and site investigation of the studied region. These data were digitized and weighed using the digital geographic information system (GIS) in a comparative manner, and then concentration and hazard of the seismic landslides were predicted using the CAMEL program. Next, by empirical comparing the landslides triggered by Sarein earthquake and the predicted concentration, the accuracy of this technique was evaluated. It can be inferred that CAMEL predicts soil landslides concentration more efficient than rock landslides. For rock slumps and block slides, CAMEL’s performance was slightly poorer. The model predicted a low occurrence of rock slumps and block slides, when none in fact occurred. A similar comparison with the Sarein case study was also conducted using a quantitative method. The accuracy of both quantitative and CAMEL approaches was evaluated using the quantitative zonation, revealing improved performance with CAMEL.

Alternative method of analysis of results of 3D terrestrial laser scanning (comment to the article “Contribution to a rock block slide examination by a model of mutual transformation of point clouds”, Acta Carsologica 38,1)

The article Konic et al. (2009) describes efforts to find out if the rock block on which the castle of Črni kal is situated slid away from the Kraški rob wall. 3D terrestrial laser scanning has been used to determine positions of many points on both presumed contact surfaces and 12-parameter affine transformation that transforms the cloud of points from one wall into another has been found. The deviation between matching point clouds has been used as a test of the original hypothesis. It has been concluded that the rock block did slide. Some of the data from the article are re-analysed using another numerical method. A 6-parameter translation composed with rotation that best transforms the 12 published points from the rock block wall into their counterparts on the Kraški rob wall is found. The original hypothesis is confirmed and some additional insight into the block slide is revealed.Keywords: rock block slide, 12-parameter affine transformation, rotation matrix, translation vector.

Development of a new translational and rotational slides prediction model in Langhe hills (north-western Italy) and its application to the 2011 March landslide event

This study outlines the relationship between antecedent precipitations and activation of the translational rock-block slides (TRBSs). This type of landslide has the peculiarity to involve wide sectors of the sedimentary bedrock, and it is emblematic in the Langhe area, in the southern hilly part of Piemonte in the Tertiary Piemonte Basin. The Langhe hills are particularly renowned for the cultivation of valuable vineyards, and therefore, constitute a place of important economic and tourist interest. Furthermore, the high density of structures and infrastructures in this area exposes a number of elements to the activity of these large landslides. In order to minimize human and economic losses, it is particularly important to establish a warning system capable of providing announcement of activation of TRBSs with sufficient advance. In this direction, the Environmental Protection Agency of Piemonte (ARPA Piemonte) developed a precipitation–threshold-based model. The model is set up on an extensive collection of historical data about the landslides movements (since 1917) and the related complete meteorological dataset. The regional weather gauge network and the forecasted precipitation amount, including snow melt’s contribution, provide input data to the model. Output model can be tested by observations derived by the regional landslides monitoring network consisting of inclinometers and groundwater gauges managed by ARPA Piemonte.

Landslide susceptibility and hazard assessment in San Ramón Ravine, Santiago de Chile, from an engineering geological approach

Debris flows and soil and rock slides are among the main geological hazards in the mountain foothills of Central Chile. Geological risk associated with the development of landslides, especially debris flows triggered in the basins of ravines that drain into the capital city, Santiago, has increased in time due to accelerated urban expansion. A landslide hazard evaluation in the San Ramon Ravine, located within the foothills of Santiago is presented. Hazard evaluation is based on a methodology that combines the determination of landslide susceptibility calculated by integration of conditioning factors, with the assessment of slope failure and runout probabilities incorporating geotechnical engineering approaches. The methodology is appropriate for medium or subregional scale studies with limited data. The results show that in San Ramon Ravine the landslide hazard consists mainly of debris flows, rock block slides, rock falls and shallow soil slides. Among these, debris flows are the most important due to the urban area that can be affected. Other case studies show that the method can be used in other regions with minor adaptations for territorial planning or for engineering and environmental purposes.

Contribution to a Rock Block Slide Examination by a Model of Mutual Transformation of Point Clouds

Basic objective of this article is to find out whether the rock block on which the castle of Crni kal is situated sticked once to the Kraški rob wall. The result is given on the basis of comparison of forms of both presumed contact surfaces represented by a great number of points determined in space. This cloud of points has been captured by 3D terrestrial laser scanning. On the basis of assessment of geological and morphological characteristics of the Crni kal rock block and the Kraški rob wall 12 characteristic pairs of corresponding (matching) points were collected, one pair consisting of two points, each from its own wall. By use of a method called 12-parameter affine transformation, transformation parameters of one cloud transformation into the other one were calculated. Since for such a transformation 4 pairs of points are enough, and there were even 12 pairs of points used in order to provide better results, the socalled least square method (LSM) was used. By the so obtained transformation vector the reference point cloud of the Crni kal rock block was transformed, for a size of the vector move back, into a cloud of transformed points which should match the reference point cloud of the Kraški rob wall. The comparison of a reference point cloud of Kraški rob and a cloud of transformed points showed that the rock block of Crni kal slid in a S-SW direction for 4.7 m in form of a block failure. Static analysis of matching point clouds proved that as much as 95 % of points fell within a distance less than 0.74 m which confirmed the hypothesis that the rock block on which the castle of Crni kal was situated represented once a part of the Kraški rob wall. Prior to the 11th century at least, it split away from it and moved parallel to the wall in form of a block failure.

A Comparison for Shear Resistant Behavior of Joints with Rock and Spiral Bolts Installed—A Numerical Approach

ABSTRACT Spiral bolt is recently developed to enhance the support capability and cost effectiveness of rock bolt type support, and previous studies show that pull-out strength of spiral bolt is superior to rock bolt owing to gearing effect of spiral shape, even though the spiral bolt has less cross sectional area. In addition to the axial reaction of rock bolt such as suspension of rock blocks, if rock block slides on joint surface, bolt should react on shear force. Many studies indicate that shear loading contributes significantly to failure, which implies that shearing behavior of rock bolt type support ought to be investigated. In this study, we made two different numerical model with single weak layer for weathered rock, soft rock and hard rock as base rock blocks: (1) cylindrical shape mortal with centered deformed bar rock bolt, (2) cylindrical shape mortal with centered spiral bolt (twisted flat bar). To investigate the effect of axial force of bolt on shear strength, numerical simulations were done for both with and without the initial axial force of bolts. The results shows that shear resistant behavior of spiral bolt for hard rock joint is slightly superior to the rock bolt, but shear resistant performance of rock bolt for soft rock and weathered rock is equivalent or slightly superior spiral bolt. Spiral bolt can be a good alternative to rock bolt as it shows high performance in both axial and shear behavior of bolts.

Ferguson rock slide buries California State Highway near Yosemite National Park

During spring 2006, talus from the toe area of a rock-block slide of about 800,000 m3 buried California State Highway 140, one of the main routes into heavily-visited Yosemite National Park, USA. Closure of the highway for 92 days caused business losses of about 4.8 million USD. The rock slide, composed of slate and phyllite, moved slowly downslope from April to June 2006, creating a fresh head scarp with 9–12 m of displacement. Movement of the main rock slide, a re-activation of an older slide, was triggered by an exceptionally wet spring 2006, following a very wet spring 2005. As of autumn 2006, most of the main slide appeared to be at rest, although rocks occasionally continued to fall from steep, fractured rock masses at the toe area of the slide. Future behavior of the slide is difficult to predict, but possible scenarios range from continued scattered rock fall to complete rapid failure of the entire mass. Although unlikely except under very destabilizing circumstances, a worst-case, rapid failure of the entire rock slide could extend across the Merced River, damming the river and creating a reservoir. As a temporary measure, traffic has been rerouted to the opposite side of the Merced River at about the same elevation as the buried section of Highway 140. A state-of-the-art monitoring system has been installed to detect movement in the steep talus slope, movement of the main slide mass, local strong ground motion from regional earthquakes, and sudden changes in stream levels, possibly indicating damming of the river by slide material.

Necessary Geomorphologic Information For Roads Safety, With Emphasize Soleghan Road In West Of Tehran, Iran

This paper review some of the aspects of necessary disciplines of geomorphology and roads, with emphasize Soleghan road. For building this road didn’t consider geomorphology process carefully. so the safety rang of the road is low and with consider to increasing traffic, the rang of danger is high. Specific subjects are related to the description of slops phenomena, including rock fall, block slide, rock creep, talus creep, debris flow, rock avalanches and floods. The river process, sloop steep, joint and fault system are the most important geomorphologic information of the Soleghan road. Soleghan road have been studied in this view and thus provide information which take the basis of stability road. Every road in Iran or world can include one or some important process, so some information is needed. More than half of Iran and world roads have built about before 1970, when the geomorphologic education and research was in the early of stage. Therefore many of Iran and world roads such as Soleghan road haven’t built with new geomorphologic and basic information. Too more damages which in order to geomorphologic process exposed to roads, people and cars in Iran and world such as Soleghan road are increased. Many flood and slumps destroyed built roads, many people and cars, damage or crash to ignoring the geomorphologic information, thus if we use geomorphologic information in road building, damage and crashes will be decreased, so safety will be increase.

Ravinement en montagne : processus, mesures, modélisation, régionalisation

Cemagref (Agricultural and Environmental Engineering Research Centre) in Grenoble and the Scientific Group "Draix, mountain erosion studies" held a conference in Digne, in the French Alps, from October 15 to 17, 2003, devoted to the theme of gully erosion in mountain areas. The aims of this international seminar were to evaluate the state of the art in research on erosion by water in uplands, to allow scientists to meet and exchange ideas on related topics, and to initiate further collaborations, with particular emphasis on field work in research basins. This meeting, which encompassed 32 oral presentations and 24 posters, was attended by 80 participants from 12 countries. A one-day scientific excursion to the Draix experimental site was dedicated to multidisciplinary researches on mountain erosion and upland floods. Gully erosion represents an important sediment source in river systems and accounts for as much as 70 to 90% of the overall sediment production of a catchment. In mountain areas, the steep slopes enhance gully processes, accelerate sediment transfer from uplands to valley bottoms and generate natural hazards: mudflows, overflowing of heavily loaded floods, silting up of reservoirs, for example. Therefore, there is a need for monitoring and for experimental and modelling studies in order to forecast the effects of climatic or land use changes on sediment dynamics in mountain catchments. In mountain environments, the development of appropriate measurement and observation techniques is quite difficult. Original devices were presented, operating from the small plot scale to the large gully and catchment scales. Several presentations focused on the processes and factors controlling erosion and gullying in mountain areas: these include mechanical breakdown and chemical weathering of rocks, bed load and suspension sediment transport, in which threshold effects have a determining influence. Mass movements are also a substantial source of sediments in steep upland basins. These may occur as superficial earth flows affecting the weathered layer, and as deep-seated landslides or rock-block slides. Several papers examined the susceptibility of the terrain to the mass movements, the conditions for landslide initiation, the relations between mass movements in black marls and rockfalls in the overlying limestone levels, and the formation and propagation of debris flows. The major role of a few paroxystic events in sediment production was pointed out by several authors. Particle detachment, mass movement initiation, and sediment transport are processes subjected to threshold effects. The connectivity in the basin network may vary from one event to the other. The studies on sediment load rates during floods showed that the availability and location of sediment stocks in the channel and gully bottoms play a greater role than the transport capacity of the flow The role of the vegetation cover in diminishing sediment yields is widely accepted. Therefore, it is still necessary to understand how the aerial parts and roots of vegetation interact with runoffand erosion in order to model the evolution of gully systems subject to climatic or land use changes. These studies show that erosion modelling becomes more complex as ole goes from the plot or slope scale to the catchment scale, which necessitates a transport-distance approach.

Some observations of landslides triggered by the 29 April 1991 Racha earthquake, Republic of Georgia

On 29 April 1991 an Ms 7.0 earthquake occurred in the Racha region of the Great Caucasus Mountains in north-central Republic of Georgia. The earthquake occurred on a thrust fault striking roughly east-west and dipping about 20 ° to 45 ° northward; focal depth was 17 --- 2 km. We observed no surface fault rupture, but the earthquake caused extensive structural damage to the many unreinforced stone buildings in the area, and at least 114 people were killed. Many landslides were triggered in a 2500-km ~ epicentral area, and they caused much of the structural damage and at least half the fatalities. We observed the following six types of landslides (in order of decreasing abundance): rock falls, debris slides, slumps, earth slides, rock block slides, and rock avalanches. The types of landslides triggered by the earthquake are controlled primarily by li- thology and geologic structure. Enigmatic landslide processes associated with this earthquake include (1) delays of several days between earthquake shaking and significant landslide movement, probably caused by changes in ground- water conditions; (2) small co-seismic displacement of landslides active at the time of the earthquake, a possible result of viscoplastic damping of the seismic shaking; and (3) somewhat unusual failure geometries related to local topog- raphy and geologic structure.

Structure of slip surface formed by rock block slide : Hayashi, Y; Higaki, D; Ishizuka, T Proc 6th International Symposium on Landslides, Christchurch, 10–14 February 1992V1, P127–133. Publ Rotterdam: A A Balkema, 1992

Structure of slip surface formed by rock block slide : Hayashi, Y; Higaki, D; Ishizuka, T Proc 6th International Symposium on Landslides, Christchurch, 10–14 February 1992V1, P127–133. Publ Rotterdam: A A Balkema, 1992

The effect of Quaternary uplift on the stability of slopes in the central part the Skorusinske Vrchy mountains in the west Carpathians

Abstract The Skorušinské vrchy mountains are part of the West Carpathians in northwest Slovakia near the Polish border. They consist of four Palaeogene sedimentary complexes and comprise a 1500 to 2000 m thick sequence of conglomerates, claystones, flyschoid rocks and sandstones. The older complexes erop out on the margins of the mountains and are covered by relatively thin clayey soils. The central part, the most highly uplifted block, consists of Eocene calcareous sandstone which are disturbed by joints and deep-seated faults. The difference in elevation between the mountain summits and the valley floors is more than 400 m. A detailed investigation of mass movement has been carried out using aerial photographs,air borne radar and satellite imagery foliowed by a field survey. Three main types of slope deformation were identified - rock block slides along bedding surfaces, rock siumps across bedding surfaces and landslides in slope debris. The occurrence of the largest and most deep-seated slides are controlled by faults. The presence of these mass deformations indicate the existence of tilted fault blocks which are the result of neotectonic arch uplift. About 15–17% of the area covered by sandstones is affected by mass movements. This paper describes the methodology of the investigation, the mechanism and genesis of slope deformations, the occurrence and parameters of slides and the role of the Quaternary uplift in the slope instability component of regional geomorphological evolution.

Large quaternary landslides in the central appalachian valley and ridge province near Petersburg, West Virginia

Geological mapping and photointerpretation of side-looking airborne radar images and color-infrared aerial photographs reveal two large Quaternary landslides in the Valley and Ridge province of the central Appalachians near Petersburg, W. Va. The Elkhorn Mountain rock avalanche occurs on the thrust-faulted northwestern flank of the Elkhorn Mountain anticlinorium. A minimum of 7 × 10 6 m 3 of quartzite colluvium was transported more than 3 km from a 91 m high escarpment of Silurian Tuscarora Quartzite. The extensively vegetated deposit may owe, in part, its transport and weathering to periglacial conditions during the Pleistocene. In contrast, the Gap Mountain rock block slide is a single allochthonous block that is 1.2 km long, 0.6 km wide, and at least 60 m thick. The 43 × 10 6 m 3 block is composed of limestone of the Helderberg Group and the Oriskany Sanstone of Early Devonian age. Planar detachment probably occurred along a dissolution bedding plane near the Shriver Chert and the Oriskany Sandstone contact. Failure probably was initiated by downcutting of the South Branch Potomac River during the Pleistocene. Landslides of this magnitude suggest accelerated erosion during periglacial climates in the Pleistocene. The recognition of these large slope failures may provide evidence of paleoclimatic conditions and, thereby, increase our understanding of the geomorphologic development of the Valley and Ridge province.

On the Relation ship between Smectite and Clinoptilolite in Some Landslides

X-ray diffraction examination in three Tertiary-Landslides, different types and sizes in Tohoku district has revealed that Detritus slump and active moved Rock glide are abundant in smectite compared with primary type of Rock block slide in slip surface.The relationship between smectite and clinoptilolite detected in clay-size material shows to be a inverse correlation and much content of smectite is almost invariabley present in the neary part of slip surface. It is suggested that smectite mainly containing in the slip surface have been derived from the alteration of clinoptilolite in consequence of cristallization in 020 direction.