Mass Movement Processes Research Articles

Rates and Processes of Mass Movement on Periglacial Rubble Slopes in Spitsbergen

Rates and Processes of Mass Movement on Periglacial Rubble Slopes in Spitsbergen

A statistic for testing the elevation characteristics of landscape simulation models

There is an urgent need to test recently constructed conceptual models of landscape evolution and geomorphology against field data. Many statistics that have commonly been used, such as Strahler statistics, are poorly suited to this testing being unable to potentially falsify the models when applied in controlled conditions. The relations between these statistics and catchment mass movement processes are, in many cases, indirect. Moreover, they are sensitive to unknowable inputs (e.g., initial conditions). One of the main differences among the competing landscape evolution models is their representation of mass movement and erosion processes, so that statistics that are directly linked to these processes, or their geomorphic signature, are needed. This paper examines the use of a log‐log linear relation between catchment area, slope, and elevation. This relation has been previously derived quantitatively from the catchment erosion and hydrologic processes for dynamic and declining geomorphic equilibria. Using a catchment evolution model, this paper shows that the relation is robust against deviations from the assumptions of spatial and temporal homogeneity of erosion, climate, and tectonic uplift made in its derivation. The sensitivity of the geomorphology to time‐varying tectonic uplift and climate and spatially variable soil erodability is examined. It is thus asserted that the relation between area, slope, and elevation is suitable for testing of models against field data, where spatial and temporal homogeneity of erosion, climate, and tectonic uplift are only approximately true. In the case of variable soil erodability, planar drainage patterns exhibit self‐organization with the high elevation regions of the catchment having low soil erodability. Consequently, a downstream increasing erodability of the soil material, consistent with a downstream fining type of behavior, is observed. It is further argued that the equilibria relation is fundamental and uniquely defines the elevation form of catchments so that all other elevation statistics are derived from it.

ロームに埋積された谷頭斜面のマスムーブメントの過程

Mass movement process of a valley-head slope is studied at a site where Kanto-loam partly covers basal granite, by means of the investigations of microtopography, geologicalmicro-structure, vegitation, and tilt-fluctuation.It is found that loam layer of the valley-head slope creeps with every rainfalls and increases the topographical instability at the lower end of valley-head slope. Consequently, slope failure on this slope is thought to occur at the lower end of valley-head slope periodically.The above mass movement process is different from the past investigated case at other valley-head slope where soil-pipe has developed at the lower end of slope. The difference of the process is probably due to the difference of the position of ground water table in slope, namely creep dominant slope has a lower ground water table and soil-pipe dominant slope has a higher one.

Laramide Tectonics and Humid Alluvial Fan Sedimentation, Ne Uinta Uplift, Utah and Wyoming

ABSTRACT Laramide uplift and erosion of the Uinta Mountains are recorded in a 10-km-long outcrop of the Lower Eocene Wasatch Formation, on the Utah-Wyoming border. This 750-m-thick package of interbedded sandstones and conglomerates is dominated by a coarsening then fining-upward megasequence 650 m thick that records the growth and abandonment of a humid alluvial fun system during a major cycle of uplift and unroofing of the thrust-bounded northern flank of the Uinta mountains. Grain size, thickness, and lateral extent of channel-complex deposits increase upward in the lower 400 m of the sequence, reflecting construction and northward progradation of the fan. Grain size and channel-complex thickness decrease upward in the upper 250 m of the sequence, reflecting gradual reduction of both sedime t yield and sediment caliber during postorogenic lowering of source-area relief. Within the megasequence, coarsening-up sequences 10-100 m thick built mainly of channel-complex deposits reflect progradation of fan lobes, punctuated by periodic fan-head avulsions. These medium-scale sequences in turn comprise small-scale fining-up cycles 1-10 m thick that reflect such fluvial processes on the fan as bar building, discrete flood events, and the filling and lateral migration of braided-stream channels. Both the medium-scale and small-scale sequences are commonly underlain by paleosols. Evidence of debris flows or other mass-movement processes is conspicuously lacking. Above the main megasequence a second, thinner megasequence containing lacustrine mudstones and wave-reworked conglomerates indicates that the fan persisted as a locus of coarse clastic deposition during the first of a series of lacustrine transgressions that began as ratios of sediment flux to subsidence rate decreased toward the end of the Early Eocene. Partial inundation of the fan during this transgression transformed it into a fan delta.

スピッツベルゲンおよびわが国の高山・山地における凍結融解による斜面物質移動

スピッツベルゲンおよびわが国の高山・山地における凍結融解による斜面物質移動

Relation between sediment yield and gradient on debris-covered hillslopes, Walnut Gulch, Arizona

Research Article| August 01, 1991 Relation between sediment yield and gradient on debris-covered hillslopes, Walnut Gulch, Arizona ATHOL D. ABRAHAMS; ATHOL D. ABRAHAMS 1Department of Geography, State University of New York at Buffalo, Buffalo, New York 14261 Search for other works by this author on: GSW Google Scholar ANTHONY J. PARSONS ANTHONY J. PARSONS 2Department of Geography, University of Keele, Keele, Staffordshire ST5 5BG, United Kingdom Search for other works by this author on: GSW Google Scholar Author and Article Information ATHOL D. ABRAHAMS 1Department of Geography, State University of New York at Buffalo, Buffalo, New York 14261 ANTHONY J. PARSONS 2Department of Geography, University of Keele, Keele, Staffordshire ST5 5BG, United Kingdom Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1991) 103 (8): 1109–1113. https://doi.org/10.1130/0016-7606(1991)103<1109:RBSYAG>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation ATHOL D. ABRAHAMS, ANTHONY J. PARSONS; Relation between sediment yield and gradient on debris-covered hillslopes, Walnut Gulch, Arizona. GSA Bulletin 1991;; 103 (8): 1109–1113. doi: https://doi.org/10.1130/0016-7606(1991)103<1109:RBSYAG>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The relation between overland-flow erosion and gradient on debris-covered semiarid hillslopes in Walnut Gulch Experimental Watershed, Arizona, is investigated by conducting three sets of field experiments under simulated rainfall on two different substrates. Each set of experiments yields a convex-upward sediment yield-gradient relation with a vertex at about 12°. The key to understanding this relation is the relation between runoff and gradient. On slopes less than 12° runoff appears to increase very slowly with gradient, and so sediment yield increases with gradient mainly in response to the increase in the downslope component of gravity. On slopes steeper than 12°, runoff decreases rapidly as gradient increases. This decrease in runoff outweighs the increase in the down-slope component of gravity as gradient increases and causes sediment yield to decrease.In all three sets of experiments, runoff is controlled by either stone cover or stone size, and stone size increases with gradient. Inasmuch as stone cover and stone size are indicators of mantle stoniness, these findings suggest that curvilinear relations between runoff and gradient and, hence, convex-upward relations between sediment yield and gradient occur only on hillslopes with coarse weathering mantles in which stoniness increases with gradient. Different combinations of substrate and climate may produce such hillslopes. They are especially likely to develop in arid and semiarid climates, but they may also form in alpine, periglacial, and humid ones where substrates are favorable. Hillslopes on which mass movement processes are the dominant denudational agents will not have convex-upward relations. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Geologic Reservoir Model for the Triassic Doig Formation, Northeast British Columbia, Canada

A subsurface investigation of the mid-Triassic Doig formation in northeastern British Columbia documented two main reservoir facies. Both are a product of mass movement and sediment gravity flow processes on a progradational, tectonically active continental shelf margin. Substrate instability was likely a product of sediment loading, perhaps in concert with seismic activity. Sedimentary facies and reservoir parameters were determined from analysis of approximately 150 cores and 900 well logs. Laterally discontinuous Doig sandstones are up to 60 m thick and trend northeasterly within the study area. The main reservoir facies are incised density flow deposits and laterally extensive slump deposits. Reservoir quality within these sands is extremely variable with porosity ranging from less than 5% to 15%. In core, these deposits consist of moderately well sorted, very fine grained sandstones with no vertical grain size variation. The best production to date is in the Buick Creek field with initial flows of 346 BOPD. The slump deposits are thinner and tend to be more elongate parallel to paleoshoreline. These sands were subject to some wave or current reworking. Modern analogs where similar processes and products of deposition are known to occur include the Gulf of Alaska continental shelf and the Frasermore » River Delta slope. Doig sandstones usually are enclosed in fine-grained shelf deposits that provide a good stratigraphic trapping mechanism. Successful development of Doig reservoirs must incorporate geologic modes that assist in understanding the complex and highly variable reservoir quality of sandstones units.« less

Results from First Direct Observation and Sampling of a Gulf of Mexico Basin Floor Salt Dome, Green Knoll

ABSTRACT In April 1990 DSV ALVIN, the deep-diving research submersible, was used to investigate the lower continental slope and adjacent basin floor off Louisiana. Green Knoll, a salt diapir with over 400 m relief above the flat-lying Gulf bottom, was a focal point of interest in the dive program. The dome is seaward of the Sigsbee Escarpment in the Walker Ridge lease block area. Seismic profiles run across this feature suggest salt at or near the sea floor. Although salt exposures were not observed, a brine pool and several active seeps were found on the east side near the crest of the dome where seismic data suggested exposure or near exposure of salt. A brine layer 12 feet thick collected in a bowl-shaped depression with steep sides. The feature was interpreted to be the result of a large sediment failure which created a cirque-like depression. Brine seeps originated in the steep walls of this feature presumably near the salt core of the dome. Elevated sodium and chloride levels in the brine suggest an origin related to the dissolution of salt. Downslope transport of brine (salinity to 7.2 higher than normal GOM water) from these seeps created drainage patterns similar to braided streams. These transport pathways were floored by bright red/orange sediments, presumably oxidized iron-rich clays. Sediment evacuation scars, gullies, shattered and deformed sediment masses, vent-like dewatering structures, stress fractures/cracks associated with incipient failures, and exaggerated slopes linked to recent episodes of mass movement were all common features of the dome flank and crest. This family of features emphasizes the importance of mass movement processes to the current configuration of the dome. Hydrocarbon seeps and commonly associated chemosynthetic communities plus authigenic carbonates were not found on top or upper flanks of the dome. End_of_Record - Last_Page 563-------

Submarine processes of the middle Atlantic continental rise based on GLORIA imagery

Approximately 6,100 km of 3.5-kHz echo-sounding profiles was correlated with a GLORIA side-scan sonar image of the mid-Atlantic United States (34°N, 70°W) lower slope-upper continental rise. The image allows us to map the major erosional and depositional features and to identify major processes that have shaped the area. The GLORIA imagery shows three approximately triangular-shaped sediment-gather areas that cover the upper-rise and slope transition areas near Wilmington, Baltimore, and Norfolk Canyons. The gather areas, which are interspersed with hemipelagic drape areas, are composed of dendritic networks of channels that extend from the base of the slope toward major channel systems on the middle rise, such as Wilmington Valley. Seaward of Cape Hatteras, a tongue-shaped area of mottled high back scatter on the GLORIA imagery denotes the Albemarle-Currituck mass-movement complex, a large (60 km wide by >190 km long) area of the sea floor that is marked by the disruption of upper-rise sedimentary strata and by mass-flow deposits. Interpretation of GLORIA imagery and echo-sounding profiles indicates that mass movement is the predominant process affecting sediment on the United States east coast mid-Atlantic slope and upper rise and that isobath-parallel sediment movement by geostrophic currents is restricted mainly to the lower continental rise. The mass-movement processes evident on the rise probably were most active during the Pleistocene, when sea level was lower and sediment input more active.

Numerical modelling of toppling

Evidence of large-scale toppling deformation has been reported in association with deep-seated landslides affecting mountain slopes along the Beaver River valley, Glacier National Park, British Columbia, Canada. A study has been undertaken to quantitatively investigate the relationship between the toppling mass movement process and the deep-seated landslides; specifically, whether the landslides represent a limiting condition of the toppling process. This is the first of two papers that describe the study. Methods of toppling analysis, including limit-equilibrium, finite-element, and distinct-element methods, are critically reviewed. The distinct-element method emerges as the best technique for modelling both block and flexural modes of toppling. The method is verified by modelling three examples of toppling: a theoretical block topple, a physical model of flexural toppling, and an engineered slope from the Brenda mine near Peachland, British Columbia. The results demonstrate that the Universal Distinct Element Code (UDEC) is capable of modelling both block and flexural types of toppling, that the toppling mass movement process limits to deep-seated planar aswell as curvilinear landslides, and that other landforms such as obsequent scarps and grabens are a manifestation of the toppling process. The research reported here contributes to understanding of the deformation behaviour of engineered slopes and the evolution of natural slopes in rock masses containing pervasive discontinuities. Key words: block toppling, flexural toppling, landslide, numerical modelling, distinct element, DDEC, sackung.

TREE UPROOTING: REVIEW OF TYPES AND PATTERNS OF SOIL DISTURBANCE

This paper reviews the processes of tree uprooting, examines the classification of pit and mound microtopography and assesses the effects of tree uprooting on soil mixing and genesis. The processes by which soil-horizon clasts are mixed as they slump off the root plate, and the ultimate patterns of soil horizonation within mounds, are primary foci of the paper. Longevity of treethrow mounds can exceed 2000 years, making these landforms more lasting features than is often assumed. Because of their great longevity, the pits and mounds formed by uprooting have lasting effects on soil morphology. Soils of these microsites often classify in different soil orders or suborders than do adjacent, less disturbed soils. The importance of tree uprooting to mass movement processes is examined. In some areas uprooting may be the primary mass wasting mechanism. Nonetheless, estimates of the amount of sediment moved and the net distance of transport vary greatly and may in some cases be overestimated. [Key words: pedotur...

鳳凰山の頂稜部砂礫地における凍結・融解期の気温および地温の変化

Gentle mass movement caused by the freeze-thaw process is very important on slopes in the alpine zone. In Japan, the mass movement process and weathering caused by the freeze-thaw process are being clarified by field experimental research. However, on the actual conditions of air temperature and soil temperature which provide for freeze-thaw processes, little research has been done, and the results are not reported in detail. Because of this the author observed air temperature and soil temperatures at 2 cm, 5 cm, and 10 cm depths continuously on the top slope of Mt. Hoo, in the northeastern part of Japan's Southern Alps (Figs. 1 and 2). The observation period was from September 24, 1986, to June 8, 1987 (258 days; absences: 15 days). As a result of this observation, the changing pattern of air temperature 1.5m above the ground surface is seen to be similar to the temperature of soil at 2cm depth. The trend of 5cm depth soil temperature is similar to that of 10 cm depth soil temperature. The diurnal cyclic freeze-thaw process is evident in air temperature and 2 cm depth soil temperature (Fig. 4). This is caused by surface rubble layer distributed below 2 cm depth (Fig. 3). The air temperature affects the 2cm depth soil temperature. However, the 2cm depth soil temperature rises over air temperature because of solar radiation, and it actually promotes the thawing process in the 2cm depth soil layer, even when the air temperature is below 0°C. This process notably occurs in the thawing period. The 5cm and 10cm depth soil temperatures show cyclic changes which are not directly affected by air temperature. During the observation period, 5cm and 10cm soil temperature stabilized at -1.5_??_-2°c for a specified period. The stabilization is caused by latent heat release when soil freezes and latent heat absorption when soil thaws; this is the so-called zero-curtain phenomena. Changes in soil temperatures are steeper in thawing periods than in freezing periods (Fig. 5). Soil temper-atures rose sharply and dropped gently during the observation period. In the thawing period, the range of diurnal change in the 2cm depth soil temperature exceeds that in air temperature caused by solar radiation. As a result of this process, the number of freeze-thaw days at 5cm and 10cm depths increases in the thawing period. The 2cm depth soil temperature rises before the air temper-ature rises in the latter half of the freeze period and the first half of the thaw period. This occurs due to solar radiation. The small-scale fluctuation of air temperature and 2cm depth soil temperature above 0°C is caused by temporary masking of solar radiation by clouds or fog. As described above, on the top slope of Mt. Hoo, the solar radiation has a very strongly effects on the mass movement of the dopes. This tendency occurs most markedly near the surface.

Deformational styles in a sequence of olistostromal mélanges, Pacific Rim Complex, western Vancouver Island, Canada

The Pacific Rim Complex is exposed in a fault-bounded slice along the west coast of Vancouver Island. It is divided into two parts: (1) the Ucluth Formation, a basement unit composed of lower Mesozoic arc-volcanic rocks, and (2) a suprajacent sedimentary sequence, more than 2 km thick, composed of Lower Cretaceous olistostromal melanges. An unconformity is present, at least locally, at the Ucluth-melange contact and indicates that the Ucluth Formation is stratigraphic basement to the melanges. Melange-style deformation is restricted to the sedimentary sequence and has affected virtually all parts of that sequence. The melanges formed without the development of a cleavage or pervasive cataclasis, indicating that deformation occurred prior to consolidation of the sediments. Three types of melanges have been recognized. The first consists of a matrix of inter-bedded mudstone, chert, sandstone, and green tuff, which encloses numerous exotic blocks of igneous rocks and limestone. Beds within the matrix show variable amounts of layer-parallel fragmentation, which is attributed to in situ liquefaction and lateral flowage within individual beds. The blocks in this melange, most of which were derived from the underlying Ucluth Formation, are considered to be submarine slide blocks, produced by rock falls from nearby basement scarps. The matrix sediments near the blocks commonly contain wispy lenses of poorly sorted plutonic and volcanic detritus (green tuff), interpreted as scree from the rock slides. The second and third types of melange are distinguished by the predominance of either mudstone or sandstone but are otherwise quite similar. These melanges lack exotic blocks and consist of a contorted assemblage of mudstone, turbidite sandstone, conglomerate, pebbly mudstone, and rare chert, all of which are depositionally interrelated. Sedimentary structures and stratal coherence are generally well preserved. The internal structure of these melanges consists of a series of dismembered depositional sequences. Individual sequences are commonly more than 75 m thick. Some are upright and others are overturned. Paleoecological evidence indicates that some of these sequences were originally deposited in an infra-slope basin. Thus, these melanges are interpreted to have formed mainly by the accumulation of large slump sheets at the base of a submarine slope. Previous interpretations have considered the Pacific Rim Complex to be a late Mesozoic subduction complex constructed along the western margin of the Wrangellia terrane (Vancouver Island). Several factors argue against a subduction-melange interpretation. (1) The melanges were deposited on an older, arc-related basement, not oceanic crust; (2) exotic blocks were introduced as rock slides and not by subsurface faulting; and (3) at least some of the strata originated in an infra-slope basin. The heterogeneous deformational style is more compatible with an origin by near-surface mass-movement processes, including submarine slides, rock falls, debris flows, and in situ liquefaction. The amount of mass wasting recorded in the Pacific Rim melanges probably requires a seismically active setting, where frequent ground shaking produced large transients in pore fluid pressure. Similarities in stratigraphy and metamorphism suggest that during Late Cretaceous time, the Pacific Rim Complex was part of the San Juan-Cascades thrust system, located 220 km to the southeast in northwestern Washington State. If this is correct, the Pacific Rim melanges would have formed on the inboard side of Wrangellia, about 30 m.y. prior to the collision of Wrangellia with the American continent. The present location of the Pacific Rim, outboard of Wrangellia, is attributed to younger (latest Cretaceous or early Tertiary) transcurrent displacement.

Process and mechanism of a rock mass movement, Part 2 (in German) : Poisel, R; Eppensteiner, N FelsbauV7, N1, Feb 1989, P16–20

Process and mechanism of a rock mass movement, Part 2 (in German) : Poisel, R; Eppensteiner, N FelsbauV7, N1, Feb 1989, P16–20

Snow avalanche terrain of the Craigieburn Range, Central Canterbury, New Zealand

Abstract An analysis of snow avalanche terrain has shown that a strong relationship exists between avalanche terrain, avalanche formation processes, and avalanche occurrence for the Craigieburn Range, New Zealand. Critical terrain factors for avalanche formation in the Craigieburn Range are open bowl-shaped slopes and open slopes in excess of 30° lying in the lee of ridges. Two types of avalanche path occur within the Craigiebum Range. The large concave paths resemble those described for Northern Hemisphere snow avalanche terrain. In contrast the short, steep rectilinear avalanche paths resemble talus slopes. The avalanche terrain of the Craigieburn Range generally reflects the effect of postglacial fluvial and mass-movement processes on highly fractured greywacke in an area of former cirque, and valley, glaciation. As most of the present skifield development occurs within avalanche terrain, careful consideration must be given to this and future development in the Craigiebum Range.

Process and mechanism of a rock mass movement, Part 1 (In German) : Poisel, R; Eppensteiner, W FelsbauV6, N4, Nov 1988, P189–194

Process and mechanism of a rock mass movement, Part 1 (In German) : Poisel, R; Eppensteiner, W FelsbauV6, N4, Nov 1988, P189–194

Geometry and Depositional Sequences of the Mississippi Canyon, Gulf of Mexico

ABSTRACT The Mississippi Canyon is one of several large canyon systems which have developed seaward of large rivers around the shelf margin of the Northern Gulf of Mexico. High-resolution geophysical and borehole data are combined to re-evaluate canyon geometry and sedimentology. Incision of the canyon appears to have taken place prior to 30,000 years BP. Canyon widening by slope failure and mass-movement processes resulted in arcuate re-entrants containing slumped debris separated by residual knolls. Much of the sediment associated with canyon formation and widening was transported down-slope, by-passing the upper canyon. Thick, laminated pro-deltaic sediments, greater than 30,000 years old, comprise the basal canyon fill. Rapid deposition along the canyon axis began about 19,000 years BP, ap arently associated with down-canyon mudflows from a nearby lowstand delta. As canyon filling progressed, mass-movement processes declined, resulting in interbedded pro-deltaic and debris flow sediments. The sediment fill was deposited in a complex cut and fill sequence suggesting a much older canyon than previously thought. Deltaic sedimentation retreated northward away from the canyon at about 7,500 years BP, and since that time a Holocene pelagic drape has been deposited.

The WOCE Hydrographic Program

The primary scientific objective of the World Ocean Circulation Experiment (WOCE) is to understand the general circulation of the global ocean well enough to be able to model its present state and predict its evolution in relation to long‐term changes in the climate. The large‐scale circulation includes ocean currents that are directly observable (for example, by current meters or ship drift) and processes of water mass formation, modification, and movement that are studied by more indirect methods. All are important to WOCE, and the determination of the “mean” The primary scientific objective of the World Ocean Circulation Experiment (WOCE) is to understand the general circulation of the global ocean well enough to be able to model its present state and predict its evolution in relation to long‐term changes in the climate. The large‐scale circulation includes ocean currents that are directly observable (for example, by current meters or ship drift) and processes of water mass formation, modification, and movement that are studied by more indirect methods. All are important to WOCE, and the determination of the “mean” circulation and also its variability on annual to decadal time and appropriate space scales is also of value.

Sedimentary Evolution of the Fan Systems of the Northern Mediterranean Margin (Gulf of Lions and Western Provence) Since the Pliocene: ABSTRACT

The continental rise of the northern Mediterranean margin is dominated by a coalescing fan-type sedimentation characterized by the complex stacking of interbedded sedimentary bodies, including symmetrical channel-levee complexes organized off the mouth of major canyons, curved ridges probably representing underdeveloped levees of asymmetrical systems, and widespread mass-movement deposits. Fan-type sedimentation in the Mediterranean basin began during the Pliocene. It first appeared ubiquitous on the deep margin and related to the Messinian paleodrainage system. Later, possibly in the early Quaternary, the sedimentation became more focused and organized off major canyons of the margin. The construction of the channel-levee complexes is inferred to have been active mainly during the drops of sea level linked with the Quaternary glaciations. In contrast, mass-movement processes are thought to have been favored during the rise of sea level characterizing the interglacial periods. On the grounds of the relative chronology of the construction of the different types of sedimentary bodies, we tentatively correlate the major active periods of the fan systems with the paleohydrographic network draining, at those times, the southern part of France. These correlations indicate that various successive regions of the Alps provided detritus to the basin through shifting feeding paths (rivers and canyons).

Seismic stratigraphy of giant mass movements, including megaturbidites, on recent continental margins

Transfer of sediments downslope by mass movement processes can be divided into rapid and slow events. The rapid events occur over a few minutes or hours, and the slow events are more continuous and take a longer period of time. Seismic records of rapid mass movement deposits are characterized by a clearly defined continuous shear surface, the lateral limits of which are unconformable, with generally chaotic or transparent internal structures, and an erosional scar. The deposits of slow mass movements are recognized by lack of a clearly defined shear surface, conformity of the lateral limits of those implied shear surfaces, stratified internal structures, stretching of upper sedimentary layers, and lack of an erosional scar.