eolian fluvial and pan playa facies of the tertiary tsondab sandstone formation in the central namib desert namibia abstract the pliocene to recent sand sea in the central part of the 2000 km long namib desert is underlain widely by sediments comprising the tsondab sandstone formation tsf of early to middle tertiary age this formation is the earliest record of terrestrial sedimentation in the central namib desert and formerly was thought to consist of only eolian dune and sand sheet deposits of a desert origin however recent field investigations indicate that the tsf also includes deposits of ephemeral watercourses and pans playas these fluvial and playa sediments are associated intimately with the eolian dune and sand sheet deposits as is likewise the case in the present extreme arid namib desert sedimentary structures and trace fossils in the tsf eolianites resemble those found in the modern sand sea furthermore these eolianites were deposited under a dominant southerly and a subordinate easterly quadrant wind regime which is similar to the present day circulation pattern in the namib since the cold benguela current was established only in the late tertiary the tsf represents a major ancestral arid phase in the namib tract that was controlled by an early anticyclonic wind regime and a geographic location on the rainshadow side of southern africa

the orange river southern africa an extreme example of a wave dominated sediment dispersal system in the south atlantic ocean sediments delivered to the south atlantic ocean by the orange river are fractionated and dispersed northwards and westwards by a vigorous longshore drift system and a number of ocean currents gravels are accreted to the coastline for a distance 300 km north from the orange river mouth sands are transported alongshore for 700 km but are in places along this transport path returned onshore by coastal winds to form the main namib sand sea and other smaller dune fields mud is more widely dispersed westwards northwards and southwards probably by slow moving ocean scale currents into basins on the shelf and onto the continental shelf edge this dispersal system operating since at least eocene times is believed to have originated during a time when there was a late cretaceous early cenozoic uplift of southern africa which resulted in 1 intensification of the existing southerly wind system 2 incision of the orange river which coupled with a shift in climate resulted in a coarsening of its sediment load delivered to the coast 3 a broad weakly subsiding or mildly uplifting inner continental shelf with little accommodation space for the sediment load of the incising orange river

provenance and transport process for interdune sands in the kumtagh sand sea northwest china abstract interdune areas are an important part of dune systems as they affect dune evolution and sand sea development however there has been little work on the provenance of interdune sediments our lack of knowledge of these sediments prevents a more complete understanding of sand sea formation and evolution in the present study we focused on the provenance of interdune sediments in the kumtagh sand sea based on their granular mineral and geochemical characteristics then further identified the spatial scope of the contribution of these sources to the interdune sediments and the associated transport mechanisms although sediment supply analysis suggested that the interdune sand may derive from the altyn tagh mountains beishan mountains and sanlongsha dune field the provenance signature based on the k rb and k ba ratios revealed that the ultimate sources were the altyn tagh mountains in the south and the beishan mountains in the north by plotting the identified provenance results on a map of the sand sea we found that the spatial scopes of contributions from these sources were separated at around 40 n however the existence of a fluvial load em1 and of reworked coarse particles em3 in the northern sand sea demonstrated that the interdune sands in this region were partly derived from the altyn tagh mountains in the south consequently by combining our results with the transport agents condition we concluded that the altyn tagh mountains supplied sediments to interdune areas by fluvial transport throughout the sand sea but that sediment in the northern sand sea was subsequently reworked and mixed with windblown sand originated from the beishan mountains

timing of natural remanent magnetization in ferriferous limestones from the swiss jura mountains abstract goethite and hematite are the main magnetic phases contained in two ferriferous middle jurassic beds which are exposed within the mandach structure the major tectonic structure of the eastern tabular jura of northern switzerland the iron oxidic phases in a reddish brown sparry limestone known as spatkalk were formed diagenetically whereas these phases are weathering products in a stratigraphically slightly younger oolitic bed the hematite in the oolitic bed was magnetized after the jura main tectonic event in the miocene whereas the hematite in the spatkalk was magnetized before the miocene the goethites in the oolitic bed carry a pretectonic and in the spatkalk a syntectonic magnetization physical and chemical data show that the goethite which was resistant to remagnetization contains an al substitution of 3 4 mol resulting in a neel temperature of 90 c the remagnetized goethite has an al content of 10 7 mol and a neel temperature of 70 c the different goethite properties indicate that the tectonic formation of the mandach structure occurred under low temperature conditions below 90 c

the effect of calcium ions in pore water on the residual shear strength of kaolinite and sodium montmorillonite this paper reviews the literature concerning the effects of pore water chemistry on residual shear strength it presents the results of index limit and residual shear strength testing undertaken on kaolinite and sodium montmorillonite using concentrations of calcium chloride similar to the calcium levels measured in groundwaters obtained from landslipped calcareous mudrock of the fuller s earth formation the residual shear strength of the sodium montmorillonite increased markedly for the sample treated and tested with 80 mg 1 cat compared with that tested with deionized water greater concentra tions of ca2 resulted in only a marginal further increase in the residual shear strength these changes were also reflected in the interpreted parameters or and c the liquid limit of the montmorillonite decreased dramatically when the samples were treated with 80 mg 1 ca2 and this effect persisted and or was slightly enhanced when the concentration of ca2 was increased the residual shear strength

a chemo mechanical insight into the failure mechanism of frequently occurred landslides in the loess plateau gansu province china abstract thick loess deposits are considered problematic soils due to their susceptibility to collapse suddenly and in large volumes upon increase of water content in the past decades a large number of landslides occurred in the loess plateau in gansu province north western china triggered by the extensive irrigation the increase of water content has been identified as a key factor controlling the loess strength however the role of long term saturation and pore fluid chemistry changes has not been investigated systematically this paper reports on an experimental study on loess samples from heitai loess terrace yongjing gansu carried out through chemical analyses oedometer and ring shear tests the natural pore fluid was found to be a concentrated saline solution in unsaturated soil condition upon saturation the pore ion concentration drop can contribute to shear strength loss in the clay component and volume decrease a prolonged exposure to the irrigation water might facilitate cement dissolution which could result in further weakening

sand residence times of one million years in the namib sand sea from cosmogenic nuclides the namib sand sea is one of the world s oldest and largest sand deserts1 yet little is known about the source of the sand in this or other large deserts2 in particular it is unclear whether the sand is derived from local sediment or comes from remote sources the relatively uniform appearance of dune sands and low compositional variability within dune fields3 make it difficult to address this question here we combine cosmogenic nuclide measurements and geochronological techniques to assess the provenance and migration history of sand grains in the namib sand sea we use u pb geochronology of detrital zircons to show that the primary source of sand is the orange river at the southern edge of the namib desert our burial ages obtained from measurements of the cosmogenic nuclides 10be 26al and 21ne suggest that the residence time of sand within the sand sea is at least one million years we therefore conclude that despite large climatic changes in the namib region associated with quaternary glacial interglacial cycles4 5 the area currently occupied by the namib sand sea has never been entirely devoid of sand during the past million years

the role of tides in beach cusp development 1 field measurements of morphology and swash flow during three episodes of beach cusp development indicate that tides modulate the height and cross shore position of beach cusps during rising tide beach cusp height decreases as embayments accrete more than horns and the cross shore extent of beach cusps decreases during falling tide beach cusp height increases as embayments erode more than horns and cross shore extent increases a numerical model for beach cusp formation based on self organization extended to include the effects of morphological smoothing seaward of the swash front and infiltration into the beach reproduces the observed spacing position and tidal modulation during rising tide water particles simulating swash infiltrate preferentially in embayments causing enhanced deposition during falling tide exfiltration of water particles combined with diversion of swash from horns causes enhanced erosion in embayments smoothing of beach morphology in the swash zone seaward of the swash front and in the shallow surf zone accounts for most of the observed tidal modulation even in the absence of infiltration and exfiltration despite the qualitative and in some cases quantitative agreement of the model and measurements the model fails to reproduce observed large deviations of horn orientation from shore normal some aspects of beach cusp shape and deviations from the basic tidal modulation possibly because of the simplified parameterization of cross shore sediment transport and the neglect of the effects of sea surface gradients on flow index terms 4546 oceanography physical nearshore processes 4255 oceanography general numerical modeling 3220 mathematical geophysics nonlinear dynamics keywords beach cusp tides infiltration exfiltration erosion

test of self organization in beach cusp formation 1 field observations of swash flow patterns and morphology change are consistent with the hypothesis that beach cusps form by self organization wherein positive feedback between swash flow and developing morphology causes initial development of the pattern and negative feedback owing to circulation of flow within beach cusp bays causes pattern stabilization the self organization hypothesis is tested using measurements from three experiments on a barrier island beach in north carolina beach cusps developed after the beach was smoothed by a storm and after existing beach cusps were smoothed by a bulldozer swash front motions were recorded on video during daylight hours and morphology was measured by surveying at 3 4 hour intervals three signatures of self organization were observed in all experiments first time lags between swash front motions in beach cusp bays and horns increase with increasing relief representing the effect of morphology on flow second differential erosion between bays and horns initially increases with increasing time lag representing the effect of flow on morphology change because positive feedback causes growth of beach cusps third after initial growth differential erosion decreases with increasing time lag representing the onset of negative feedback that stabilizes beach cusps a numerical model based on self organization initialized with measured morphology and alongshore uniform distributions of initial velocities and positions of the swash front at the beginning of a swash cycle reproduces the measurements except for parts of one experiment where limited surveys and a significant low frequency component to swash motions might have caused errors in model initialization

chemo mechanical effects in kaolinite part 1 prepared samples the results of laboratory tests on chemo mechanical interactions in kaolinite samples prepared with inorganic salt acid and base solutions are presented in particular the effects of the different solutions on the liquid limit one dimensional compressibility permeability and residual shear strength are considered kaolinite proves relatively insensitive to salt solutions whereas variations in pore fluid ph cause large strength changes associated with non negligible changes in one dimensional compressibility the partly inconsistent effects induced by acids and bases on the residual shear strength and on the one dimensional compressibility do not permit any easy interpretation of the experimental evidence mineral dissolution and the associated formation of new compounds are probably involved in the behaviour observed these aspects will be investigated in part 2 of this paper

residual strength of kaolin and bentonite the influence of their constituent pore fluid the residual strength of clays is affected by their mineral composition and by the nature of their constituent pore fluid in principle both factors may influence either strength parameters or stresses but it is not yet completely clear how this influence works previous publications have elucidated some aspects of clay residual strength behaviour this paper investigates further the roles of minerals and pore fluid composition on the residual strength of clayey soils it describes and analyses tests on kaolin bentonite and their mixtures exposed to distilled water and sodium choride solutions with given concentrations the results show that the shear strength of kaolin is not affected by the solutions used whereas the residual strength of bentonite varies greatly because of the inward salt diffusion towards the clay further for the clay mixtures with any of the pore fluids considered the weaker component has the greater influence on the behaviour of the mixture la resistance residuelle des argile

analyses of iron oxide assemblages within namib dune sediments using high field remanence measurements 9 t and mossbauer analysis

morphodynamics of nearshore rhythmic sandbars in a mixed energy environment sw france i mapping beach changes using visible satellite imagery abstract this paper presents a new method to analyze the morphology and migration of shallow water sandbanks based on the retrieval of maps from high resolution spot satellite imagery this approach was applied to the study of intertidal ridge and runnel systems and subtidal crescents that border the southwest coast of france maps were obtained from 16 spot images recorded between 1986 and 2000 ridge and runnel shapes with regard to a reference level were delineated using a watercolor reflectance code parameterized and validated with field data crescent plan shapes which appear on the images due to water transparency or breaking induced foam were directly extracted the spatial maps show that in conformity with field surveys the mean alongshore spacing of intertidal systems and crescents range from 370 146 m variability is indicated by standard deviation to 462 188 m and from 579 200 to 818 214 m respectively several couples of images also show that ridge and runnel systems and crescents move in the longshore drift direction southward by about 2 4 3 1 and 1 m day 1 respectively alongshore migration rates of intertidal systems are confirmed by field surveys whilst crescent dynamics cannot be validated because there is no in situ data available to complete these measurements an analysis of the influence of wave climate on both the shape and movements of these rhythmic sedimentary patterns is proposed in a companion paper

self organization mechanisms for the formation of nearshore crescentic and transverse sand bars the formation and development of transverse and crescentic sand bars in the coastal marine environment has been investigated by means of a nonlinear numerical model based on the shallow water equations and on a simplified sediment transport parameterization by assuming normally approaching waves and a saturated surf zone rhythmic patterns develop from a planar slope where random perturbations of small amplitude have been superimposed two types of bedforms appear one is a crescentic bar pattern centred around the breakpoint and the other herein modelled for the first time is a transverse bar pattern the feedback mechanism related to the formation and development of the patterns can be explained by coupling the water and sediment conservation equations basically the waves stir up the sediment and keep it in suspension with a certain cross shore distribution of depth averaged concentration then a current flowing with against the gradient of sediment concentration produces erosion deposition it is shown that inside the surf zone these currents may occur due to the wave refraction and to the redistribution of wave breaking produced by the growing bedforms numerical simulations have been performed in order to understand the sensitivity of the pattern formation to the parameterization and to relate the hydro morphodynamic input conditions to which of the patterns develops it is suggested that crescentic bar growth would be favoured by high energy conditions and fine sediment while transverse bars would grow for milder waves and coarser sediment in intermediate conditions mixed patterns may occur

test of edge wave forcing during formation of rhythmic beach morphology 1 this paper reports on concurrent measurements of evolving rhythmic beach morphology and the associated water motion on a macrotidal coarse sandy beach beach cusps with a spacing of 19 m developed over a 3 day period of low energy swell after which they were destroyed by energetic wind waves the beach cusps were clearly accretionary features and developed mainly during the rising tide detailed hydrodynamic measurements were conducted at three locations in the swash and inner surf zone in the vicinity of a developing cusp horn and revealed that energetic standing mode zero subharmonic edge waves were not present during the initiation of the beach cusps specifically analysis of the hydrodynamic data indicated that 1 the amount of subharmonic energy was limited 10 of the total energy 2 none of the computed energy spectra exhibited a significant peak at the subharmonic frequency 3 the cross shore velocity amplitude at the subharmonic frequency was 2 3 times larger than the longshore velocity amplitude 4 the longshore current motion at the subharmonic frequency was barely coherent between adjacent locations in the surf zone and 5 the time series of pressure and cross shore current were in phase at either side of the developing cusp horn it is concluded that at least during this event of beach cusp formation energetic standing edge waves are not a prerequisite to initiate the development of rhythmic beach morphology

late pliocene vegetation and climate in namibia southern africa derived from palynology of odp site 1082 the present day condition of bipolar glaciation characterized by rapid and large climate fluctuations began at the end of the pliocene with the intensification of the northern hemisphere continental glaciations the global cooling steps of the late pliocene have been documented in numerous studies of ocean drilling program odp sites from the northern hemisphere however the interactions between oceans and between land and ocean during these cooling steps are poorly known in particular data from the southern hemisphere are lacking therefore i investigated the pollen of odp site 1082 in the southeast atlantic ocean in order to obtain a high resolution record of vegetation change in namibia between 3 4 and 1 8 ma four phases of vegetation development are inferred that are connected to global climate change 1 before 3 ma extensive rather open grass rich savannahs with mopane trees existed in namibia but the extension of desert and semidesert vegetation was still restricted 2 increase of winter rainfall dependent renosterveld like vegetation occurred between 3 1 and 2 2 ma connected to strong advection of polar waters along the namibian coast and a northward shift of the polar front zone in the southern ocean 3 climatically induced fluctuations became stronger between 2 7 and 2 2 ma and semiarid areas extended during glacial periods probably as the result of an increased pole equator thermal gradient and consequently globally enhanced atmospheric circulation 4 aridification and climatic variability further increased after 2 2 ma when the polar front zone migrated southward and the influence of atlantic moisture brought by the westerlies to southern africa declined it is concluded that the positions of the frontal systems in the southern ocean which determine the locations of the high pressure cells over the south atlantic and the southern indian ocean have a strong influence on the climate of southern africa in contrast to the climate of northwest and central africa which is dominated by the saharan low pressure cell

concepts in gravel beach dynamics abstract the dominant processes in gravel beach dynamics are reviewed highlighting some common themes which unify the various components of the gravel beach system the repercussions of which impart on how gravel beach dynamics might be understood conceptually in particular gravel beach dynamics are thought to be highly dependent on the temporal and spatial variation in grain size and the continual adjustments made by an active beach step both of which act not only as the expression of changing morphodynamic conditions but also as a controlling influence morphodynamics the notion that the exchanges on beaches between the hydrodynamics sediment transport and morphological change takes the form of reciprocal relationships which are mediated through feedback mechanisms in such a way that they cannot be thought of or studied independently is not a new one yet it appears that for the gravel beach morphodynamics must be re defined to describe conditions where variations in sediment size are thought to deserve parity rather than as merely a sequent entity or boundary condition morpho sedimentary dynamics is a phrase coined to intuit such cause and effect detailing the co evolution of morphology hydro hydraulics and sediment properties whilst acknowledging causative pluralism feedbacks and multiplier effects this is the recommended conceptual framework within which to crystallise thought and organise further research for the gravel beach essentially it increases the minimum number of parameters needed to describe the state of the gravel beach as a physical system therefore it is advised that simplicity will be most expedient in our future modelling efforts if complexity is to be adequately encapsulated

observations of nonlinear runup patterns on plane and rhythmic beach morphology 1 application of nonlinear forecasting and bispectral analysis to video observations of runup over cuspate topography shows that these alongshore patterns in the morphology are accompanied by changes to the fundamental behavior of the runup time series nonlinear forecasting indicates that at beach cusp horns the behavior of swash flow is more predictable and global meaning that characteristics of individual swash events are well represented by the behavior of the time series as a whole conversely at beach cusp bays the behavior of swash flow is less predictable and more local meaning that the characteristics of individual swash events are best represented by the behavior of a small fraction of the time series bispectral analysis indicates that there is a nonlinear transfer of energy from the incident wave frequency f to the infragravity frequency f 2 which only occurs in the bay suggesting that the local behavior is caused by interactions between successive swash cycles which are magnified by channeling caused by the beach cusp geometry the local behavior and the bispectral signatures are not present in offshore measurements and they are not present in runup time series collected when the beach was planar these results provide evidence that interactions between successive runups are a fundamental characteristic of beach cusp bays ultimately these interactions could lead to the growth of an infragravity wave with an alongshore wavelength forced by the presence of beach cusps

spectral properties iron oxide content and provenance of namib dune sands this paper applies multispectral remote sensing techniques to map the fe oxide content over the entire namib sand sea spectrometric analysis is applied to field samples to identify the reflectance properties of the dune sands which enable remotely sensed fe oxide mapping the results indicate that the pattern of dune colour in the namib sand sea arises from the mixing of at least two distinct sources of sand a red component of high fe oxide content present as a coating on the sand grains which derives from the inland regions particularly from major embayments into the southern african escarpment and a yellow coastal component of low fe oxide content which is brought into the area by northward moving aeolian transport processes these major provenances are separated by a mixing zone between 20 km and 90 km from the coast throughout the entire length of the sand sea previous workers have also recognised a third fluvial provenance but the methodology applied here is not able to map this source as a distinct spectral component

the formation of the namib sand sea inferred from the spatial pattern of magnetic rock fragments the formation of the namib sand sea inferred from the spatial pattern of magnetic rock fragments

age and dynamics of linear dunes in the namib desert bristow c s duller g a t lancaster n 2007 age and dynamics of linear dunes in the namib desert geology 35 6 555 558 sponsorship american chemical society

investigation of a self organization model for beach cusp formation and development a recent numerical investigation of self organization werner and fink 1993 suggests that the feedback process between currents and sediment response can result in self organized patterns and can be used to predict beach cusp formation and spacing a similar model based on self organization is tested here in order to understand the processes occurring during beach cusp formation and development to evaluate the sensitivity toward the parameters used and to examine how the model might relate to field observations results obtained confirm the validity of the self organization approach and its capacity to predict beach cusp spacing with values in fair agreement with the available field measurements with most of the input parameters primarily affecting the rate of the process rather than the final spacing however changes in the random seed and runs for large numbers of swash cycles reveal a dynamical system with significant unpredictable behavior cusp spacing tends to change with time and cusp regularity shows large long term variations cusps are found to be accretionary in the swash zone and in agreement with most observations mean flows are horn divergent over developed topography simulations over nonplanar slopes characterized by the presence of preexisting nonrhythmic or cuspate features have been performed results indicate that preexisting large amplitude cusps are destroyed if their spacing is substantially different from that expected under self organization and that the final spacing is consistent with that predicted by the model for an equivalent plane beach these findings support the hypothesis that self organization is a robust mechanism for beach cusp formation

the chemical and mineralogical controls upon the residual strength of pure and natural clays recent work has shown that the residual strength of clays is to a large extent determined by the type of clay minerals and the chemistry of the constituent pore water changes in either of these factors cause corresponding alterations in residual shear strength the findings have important implications for the seasonal reactivation of landslides and may also provide an explanation for the long term weathering and shear strength reduction of clay slopes results are presented here to demonstrate the separate effects of clay mineralogy and pore water chemistry upon the residual strength of pure and natural clays explanations are sought to identify the controls of these factors upon residual strength based on brief reviews of the shear strength and physico chemical behaviour of clays the findings strongly suggest that residual strength should be considered a dynamic property with increases or decreases in strength occurring in response to environmental change des etudes recentes ont montre que la resis

morphometric and sediment analysis of beach cusp in correlation to rip currents a case study from tropical coast west coast of india the presence of rhythmic beach cusps in foreshore regions are of persistent research interest to coastal researchers engineers with respect to their formation in beaches morphometric and sediment analysis were used to study beach cusp morphology at vengurla beach a gentle slope beach characterized by medium sand the cusp dimensions such as spacing elevation amplitude and depth were measured for detailed analysis the distinctive sediment characteristics between the horn and the bays of the cusp are different and cusp measurements show a high level of irregularity horns and bays have medium sand but sorting is varying sorting variations clearly demonstrated the difference in energy condition between horns and bay negative skewness of few horn samples has been correlated with erosional trend based on the grain size analysis result it was observed that vengurla beach cusps follow the regular grain size distribution pattern additionally the low intensity rip currents were also noticed in the study area the rate of occurrence and strength of rip currents are decided by the nearshore bathymetry and play an imperative role in rip current formation the present study is based upon the field measurements along vengurla coast and contributes to morphometric analysis of beach cusps regarding beach cusps there are no documented databases along the indian coast understanding the beach cusp formation and its seasonal changes along the beaches will be useful for effective coastal management

pliocene pleistocene variability of upwelling activity productivity and nutrient cycling in the benguela region in this study we present combined high resolution records of sea surface temperature sst phytoplankton productivity and nutrient cycling in the benguela upwelling system bus for the past 3 5 ma the sst record provided evidence that upwelling activity off namibia mainly intensified ca 2 4 2 0 ma ago in response to the cooling of the southern ocean and the resultant strengthening of trade winds as revealed by productivity related proxies bus intensification led to a major transition in regional biological productivity when considering the termination of the matuyama diatom maximum a diatom high production event major oceanic reorganization in the benguela was accompanied by nutrient source changes as indicated by a new nitrogen isotopic delta n 15 record that revealed a stepwise increase at ca 2 4 and ca 1 5 ma ago the change in source region likely resulted from significant changes in intermediate water formation tied to the reorganization of oceanic conditions in the southern ocean which may have in turn mainly controlled the global ocean n cycle and therefore the n isotopic composition of nutrients since 3 5 ma ago

recognition and palaeoclimatic implications of late quaternary niche glaciation in eastern lesotho geomorphic evidence of former glaciation in the high drakensberg of southern africa has proven controversial with conflicting glacial and non glacial interpretations suggested for many landforms this paper presents new geomorphological sedimentological and micromorphological data and glacier mass balance modelling for a site in the leqooa valley eastern lesotho preserving what are considered to be moraines of a former niche glacier that existed during the last glacial maximum lgm the geomorphology and macro sedimentology of the deposits display characteristics of both active and passive transport by glacial processes however micromorphological analyses indicate a more complex history of glacial deposition and subsequent reworking by mass movement processes the application of a glacier reconstruction technique to determine whether this site could have supported a glacier indicates a reconstructed glacier equilibrium line altitude ela of 3136 m a s l and palaeoglacier mass balance characteristics comparable with modern analogues reflecting viable if marginal glaciation radiocarbon dates obtained from organic sediment within the moraines indicate that these are of lgm age the reconstructed palaeoclimatic conditions during the lgm suggest that snow accumulation in the drakensberg was significantly higher than considered by other studies and has substantial relevance for tuning regional climate models for southern africa during the last glacial cycle copyright 2009 john wiley sons ltd

undrained shear behavior of loess saturated with different concentrations of sodium chloride solution abstract a series of ring shear tests was conducted on saturated loess to investigate the effects of nacl concentration in pore water and desalinization on the shear behavior under undrained conditions the loess samples were taken from the ground surface of a frequently active landslide in china were saturated by de aired distilled water with different concentrations of nacl and then were sheared undrained after that the samples were retrieved remolded re set into the shear box and re saturated by passing through de aired distilled water such that the samples were desalinized and then were sheared undrained again through comparing the undrained shear behavior the effects of nacl in the pore water and desalinization on the undrained shear behavior of loess were examined the results showed that the variation of nacl concentration in pore water can strongly affect the shear behavior of saturated loess both the peak shear strength and steady state strength increased with increase of nacl concentration until a certain value after which they decreased with further increase of nacl concentration meanwhile the peak shear strength and steady state strength of the desalinized samples recovered to those of the original sample hence the effects of salinization are reversible these findings may be of practical importance to better understand the repeated occurrence of some irrigation induced loess landslides in china