sediment dates with implications for the age of the conversion from palaeochannel to modern fluvial activity on the murray river and tributaries abstract dates for sediment deposition have been obtained for a number of abandoned channels with modern features on the upper murray kiewa ovens and goulburn rivers and from palaeochannel deposits on the upper murray river just west of albury the dates from modern channels on the upper murray are problematic but suggest modern fluvial activity had begun by 5 9 ka two dates from the ovens and kiewa rivers are in agreement with this west of albury a palaeochannel point bar returned an age of 7 4 11 6 ka and a source bordering sand dune 22 5 ka sand beneath the floodplain near albury was aged 7 3 ka and was not deposited at the same time as underlying gravels where two embedded trees returned ages of 12 ka it therefore cannot be established if the sand deposit was associated with either modern or palaeochannel activity therefore on the upper murray river the transition from palaeochannel to modern fluvial activity most likely occurred between 7 and 10 ka in contrast two dates from an abandoned channel on the goulburn river indicates that modern channels were active on this river before 11 13 ka this suggests that palaeochannels were active later on the upper murray than on the goulburn river and compared with previous work possibly later than on the murrumbidgee river and the middle murray river near echuca as upper catchment areas were revegetated following the lgm discharge or sediment supply may have declined first in lower altitude catchments like the goulburn and last in the high altitude upper murray catchment creating an asynchronous transition from palaeochannel to modern fluvial activity in subcatchments of the southeast murray drainage basin

revisiting an arid lgm using fluvial archives a luminescence chronology for palaeochannels of the murrumbidgee river south eastern australia the riverine plain in south eastern australia contains numerous palaeochannels that are much larger than the present rivers and provide evidence about past hydrological conditions previous research suggested optima in fluvial activity both before and after the peak of the last glacial maximum lgm 21 3 ka and in some cases throughout the lgm in this study we revisit palaeochannel remnants of the gum creek and yanco palaeochannel systems along the murrumbidgee river which drains the high elevation catchments of the australian alps in south eastern australia we date fluvial and aeolian sediments using single grain optically stimulated luminescence osl and apply thermoluminescence tl dating to a subset of samples we compare the osl ages to new and previously published tl ages and investigate reasons for age discrepancies between these methods possible effects of partial bleaching and other factors that may affect luminescence ages we propose a new osl based chronology for the gum creek and yanco palaeochannel systems and assign periods of enhanced fluvial activity for the tombullen and yanco phases to 41 29 and 29 18 ka respectively importantly we infer that conditions of increased sediment and water discharge persisted for the murrumbidgee river at the time of the lgm

climatic records over the past 30 ka from temperate australia a synthesis from the oz intimate workgroup temperate australia sits between the heat engine of the tropics and the cold southern ocean encompassing a range of rainfall regimes and falling under the influence of different climatic drivers despite this heterogeneity broad scale trends in climatic and environmental change are evident over the past 30 ka during the early glacial period 30 22 ka and the last glacial maximum 22 18 ka climate was relatively cool across the entire temperate zone and there was an expansion of grasslands and increased fluvial activity in regionally important murray darling basin the temperate region at this time appears to be dominated by expanded sea ice in the southern ocean forcing a northerly shift in the position of the oceanic fronts and a concomitant influx of cold water along the southeast including tasmania and southwest australian coasts the deglacial period 18 12 ka was characterised by glacial recession and eventual disappearance resulting from an increase in temperature deduced from terrestrial records while there is some evidence for climatic reversals e g the antarctic cold reversal in high resolution marine sediment cores through this period the high spatial density of holocene terrestrial records reveals an overall expansion of sclerophyll woodland and rainforest taxa across the temperate region after 12 ka presumably in response to increasing temperature while hydrological records reveal spatially heterogeneous hydro climatic trends patterns after 6 ka suggest higher frequency climatic variability that possibly reflects the onset of large scale climate variability caused by the el nino southern oscillation

reduction in fully softened shear strength of natural clays with nacl leaching and its effect on slope stability abstractlandslides and slope failures in natural clay rich materials are frequently observed in coastal areas and other areas where these materials were deposited in a saline water environment high sodium chloride nacl concentration in the pore fluid results from deposition in this environment as shown by the results of this study subsequent reduction in the nacl concentration results in reduction in fully softened shear strength with potentially significant reduction in slope stability fourteen sample materials were collected from seven different landslide areas in niigata prefecture japan to evaluate the effect of saline water on fully softened shear strength fsss the sample materials were collected from the intact mudstones and the sliding surface materials pore waters from the powdered sliding surface materials exhibited low concentrations of nacl however the pore waters in the powdered intact rock samples exhibited a high concentration of nacl washing of nacl from the powdered intact

palaeoclimatological and chronological implications of the vostok core dust record the2 083 m vostok ice core recovered by the soviet antarctic expeditions has provided much information of climatic and environmental interest for a period covering a full glacial inter glacial cycle1 6 here we present and discuss the dust record obtained down to 2 202 m the final depth to which this core was extended in 1986 first we document the fact that major changes in aeolian deposits as recorded in the vostok core appear to be of global significance and confirm the existence of a link between high latitude aeolian deposits and the earth s orbital parameters7 8 second we propose atmospheric dust as a strati graphic marker to compare timing with other records of palaeocli mate and use the magnetic susceptibility profile measured along the rc11 120 indian ocean core9 for this purpose assuming that major dust events correspond to common aeolian inputs this approach indicates that the vostok and marine records were roughly in phase at the previous glacial interglacial transition

late quaternary climates of the australian arid zone a review abstract aridity in australia has generally been associated with glacial intervals of the last few glacial cycles the causes and nature of aridity varied from north to south over the continent in northern and central australia reduced monsoon rain in global cold stages caused lakes and rivers to dry vegetation to become more sparse sand dunes to become active and dust advection to increase while the monsoon is correlated with warmer global temperatures and high sea levels overall the exact timing of the greatest development of the monsoon in stage 5 remains uncertain in southeastern australia the proxy records give a less clear picture while vegetation seems to have been more sparse in cold stages and sand dune activity and dust flux consequently greater records of runoff in rivers and lakes have mixed or opposite behaviour to northern or central australia the nature of aridity in southeastern australia is not analogous to conditions anywhere on the continent today greatly reduced temperatures over the central and southern interior greater influence of snow and periglaciation on runoff high groundwater tables lower rainfall and reduced atmospheric carbon dioxide levels may all have contributed to and interacted to produce the reconstructed picture of a cold sparsely vegetated arid landscape with large rivers and perennial lakes the largest changes in circulation patterns over the glacial cycle probably occurred in the location and or intensity of summer tropical convergence in northern australia over southern australia changes to the temperature and humidity of the westerly circulation have been more significant than the small fluctuations in latitude of the sub tropical high pressure ridge

frictional properties of simulated fault gouges from the seismogenic groningen gas field under in situ p t chemical conditions we investigated the frictional properties of simulated fault gouges derived from the main lithologies present in the seismogenic groningen gas field ne netherlands employing in situ p t conditions and varying pore fluid salinity direct shear experiments were performed on gouges prepared from the carboniferous shale siltstone substrate the upper rotliegend slochteren sandstone reservoir the overlying ten boer claystone and the basal zechstein anhydrite carbonate caprock at 100 c 40 mpa effective normal stress and sliding velocities of 0 1 10 m s as pore fluids we used pure water 0 5 6 2 m nacl solutions and a 6 9 m mixed chloride brine mimicking the formation fluid our results show a marked mechanical stratigraphy with a maximum friction coefficient of 0 66 for the basal zechstein a minimum of 0 37 for the ten boer claystone 0 6 for the reservoir sandstone and 0 5 for the carboniferous mixed gouges showed intermediate values pore fluid salinity had no effect on frictional strength most gouges showed velocity strengthening behavior with little systematic effect of pore fluid salinity or sliding velocity on a b however basal zechstein gouge showed velocity weakening at low salinities and or sliding velocities as did 50 50 mixtures with sandstone gouge tested with the 6 9 m reservoir brine from a rate and state friction viewpoint our results imply that faults incorporating basal zechstein anhydrite carbonate material at the top of the reservoir are the most prone to accelerating slip that is have the highest seismogenic potential the results are equally relevant to other rotliegend fields in the netherlands and n sea region and to similar sequences globally

buffers barriers and blankets the dis connectivity of catchment scale sediment cascades abstract catchment configuration and the nature of connectivity within and between landscape compartments affect the operation of sediment cascades and geomorphic responses to disturbance events of differing magnitude and frequency this paper introduces the concept of landform impediments termed buffers barriers and blankets that impede sediment conveyance by limiting the connectivity between landscape compartments buffers restrict sediment delivery to channels barriers inhibit sediment movement along channels and blankets drape channel or floodplain surfaces affecting the accessibility of sediment to entrainment these features operate as a series of switches which turn on off processes of sediment delivery determining the effective catchment area at any given time using previously documented examples the role of these features in affecting the operation of sediment cascades in a low relief passive landscape setting such as the australian landmass is contrasted to examples from high relief uplifting settings in new zealand the australian examples are further explored by examining how changes to landscape connectivity brought about by human disturbance since european settlement have impacted upon landscape sensitivity and prospects for river recovery this approach to analysis of impediments to sediment conveyance is generic and can be applied in any environmental setting

variation in residual shear strength of the soil with the salinity of pore fluid slope stabilization procedures for seven landslides in the niigata prefecture of japan had provided an excellent and rare opportunity to examine the composition of ground water and residual shear strength of the sliding surface soil as well as unsheared mudstone ring shear tests were conducted on the soil samples collected from sliding surface soil revealed during the installation of 3 m diameter drainage galleries shear strength and index properties of the soil were measured by mixing the soil with distilled water and sea water and after leaching the nacl from the pore water the residual shear strength of the soil sample with distilled water was 3 5 lower than that with the sea water the residual shear strength of the intact rock powder after leaching the dissolved salt was close to that of the soil from sliding surface and the residual shear strength of the soil from sliding surface after mixing with sea water was close to that of the intact rock powder the increase in residual shear strength

a mechanism for the formation of overconsolidated horizons within estuarine floodplain alluvium implications for the interpretation of holocene sea level curves

seawater effect on consistency limits and compressibility characteristics of clays the reported results in the literature indicate that there is a discrepancy regarding seawater effect on the consistency limits and compressibility properties of clayey soils having relatively low and high plasticity to clarify this discrepancy consistency limits including liquid plastic and shrinkage limits sediment volume and compressibility characteristics of ten soils were tested using distilled water and natural seawater from the aegean sea the results indicate that the effect of seawater is negligible on the tested consistency limits and compressibility characteristics of soils when they have liquid limits up to 110 the seawater effect is most noticed on the consistency limits and compressibility of na bentonites the results of previous research were compiled and compared with those obtained in this study all reported data were normalized by dividing the index values obtained using seawater by those obtained using distilled water the comparison of data indicate that the compiled data and present study data are in good agreement i e when the normalized values are plotted as function of liquid limit all index properties plot along the unity line until the liquid limit of soils is about 110 then the normalized index values decrease almost linearly with liquid limit

some geological implications of average quaternary glacial conditions analyses of quaternary landscape evolution tend to focus on events associated with culminations of glacial and interglacial ages but for most of quaternary time environments were intermediate in character average quaternary glacial conditions based on assessment of the marine isotope record approximated those near the stage 2 stage 1 transition and during substages 5b and 5d isotope stages 3 and 4 and substages 5a d lie within one standard deviation of the mean value under average glacial conditions ice sheets lying over northern north america and europe were much more contracted than their full glacial counterparts and the distribution of mountain glaciers reflected a snowline depression of some 500 m geomorphic processes operating under average quaternary conditions contributed importantly to landscape evolution examples of landscapes that may represent such average conditions include cirques and fluvial deposits of the pacific northwest the fjords and strandflat of western norway and atolls of the tropical oceans by examining the geologic record from the perspective of average conditions rather than those of climatic extremes added insight can be gained regarding the evolution of quaternary landscapes

anabranching rivers their cause character and classification anabranching rivers consist of multiple channels separated by vegetated semi permanent alluvial islands excised from existing floodplain or formed by within channel or deltaic accretion these rivers occupy a wide range of environments from low to high energy however their existence has never been adequately explained they occur concurrently with other types of channel pattern although specific requirements include a flood dominated flow regime and banks that are resistant to erosion with some systems characterized by mechanisms to block or constrict channels thereby triggering avulsion the fundamental advantage of an anabranching river is that by constructing a semi permanent system of multiple channels it can concentrate stream flow and maximize bed sediment transport work per unit area of the bed under conditions where there is little or no opportunity to increase gradient on the basis of stream energy sediment size and morphological characteristics six types of anabranching river are recognized types 1 3 are lower energy and types 4 6 are higher energy systems type 1 are cohesive sediment rivers commonly termed anastomosing with low w d ratio channels that exhibit little or no lateral migration they are divisible into three subtypes based on vegetative and sedimentary environment type 2 are sand dominated island forming rivers and type 3 are mixed load laterally active meandering rivers type 4 are sand dominated ridge forming rivers characterized by long parallel channel dividing ridges type 5 are gravel dominated laterally active systems that interface between meandering and braiding in mountainous regions type 6 are gravel dominated stable systems that occur as non migrating channels in small relatively steep basins anabranching rivers represent a relatively uncommon but widespread and distinctive group that because of particular sedimentary energy gradient and other hydraulic conditions operate most effectively as a system of multiple channels separated by vegetated floodplain islands or alluvial ridges

downstream hydraulic geometry of rivers in victoria australia abstract downstream variation of hydraulic geometry in rivers characterized by fine textured banks and low width to depth ratios 7 25 is investigated in victoria australia with the aim of developing predictive models of channel geometry for large scale spatial modeling applications a one dimensional hydraulic model is used to determine the mean bank full geometry and discharge q bf for 93 sites which are investigated in relation to discharge of fixed average recurrence interval ari the median bank full ari is estimated at 0 8 years with 75 of sites between 0 5 and 2 5 years exponents in the downstream hydraulic geometry relations for width depth and velocity are respectively 0 43 0 40 and 0 18 q q bf and 0 44 0 38 and 0 03 q q 2 i e 2 year ari falling near the mode of global values q 2 and slope explain 66 of variance in q bf while q 2 explains 73 and 69 of the variance in width and depth relations respectively q 2 provides a reliable substitute for q bf in spatial modeling applications spatial variation in hydraulic geometry relations within and between river basins remains largely unexplained the w d ratio characteristically decreases with increasing distance along the lower reaches of most rivers and this has contributed to the lower than expected value for the width exponent

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

dramatic reduction in size of the lowland macquarie river in response to late quaternary climate driven hydrologic change palaeochannels of lowland rivers provide a means of investigating the sensitivity of river response to climate driven hydrologic change about 80 palaeochannels of the lower macquarie river of southeastern australia record the evolution of this distributive fluvial system six macquarie palaeochannels were dated by single grain optically stimulated luminescence the largest of the palaeochannels quombothoo median age 54 ka was on average 284 m wide 12 times wider than the modern river 24 m and with 21 times greater meander wavelength palaeo discharge then declined resulting in a younger narrower group of palaeochannels bibbijibbery 125 m wide 34 ka billybingbone 92 m 20 ka milmiland 112 m 22 ka and mundadoo 86 m 5 6 ka yet these channels were still much larger than the modern river and were continuous downstream to the confluence with the barwon darling river at 5 5 ka a further decrease in river discharge led to the formation of the narrow modern river the ecologically important macquarie marshes and marra creek palaeochannel 31 m 2 1 ka and diminished sediment delivery to the barwon darling river as palaeo discharge fell further the hydrologic changes suggest precipitation was a driving forcing on catchment discharge in addition to a temperature driven runoff response

estimates of late holocene soil production and erosion in the snowy mountains australia soil production in actively uplifting or high precipitation alpine landscapes is potentially rapid however these same landscapes are also susceptible to erosion and can be sensitive to changes in climate and anthropogenic activity which can upset the balance between soil production and erosion the snowy mountains southeastern australia are a tectonically stable low relief moderate precipitation mountain environment the alpine area is extensively blanketed by soil that has been subjected to more intensive episodes of erosion during past periods of anthropogenic disturbance and under cold climate conditions of the late quaternary in this study rates of soil development and hillslope erosion were investigated using radiocarbon dating fallout radionuclides and sediment cores collected from lakes and reservoirs estimated holocene soil development rates were 20 220 t km y erosion rates determined from the radionuclides cs and pb were equivocal due to the inherent spatial variability of radionuclide inventories relative to apparent erosion rates estimated average erosion rates over the past 100 years determined from pb inventories were 60 t km y 95 ci 10 90 inventories of cs observed at the same site implied that more recent erosion rates over the past 60 years was below the detection limits of the sampling method applied here i e 70 t km y the upper estimate of 90 t km y is comparable to the mean erosion rate estimated using the radionuclide method for uncultivated sites in australia and is significantly lower than that measured at sites were vegetation cover was disturbed by livestock grazing prior to its exclusion from the alpine area in the 1940s ce low erosion and high soil production rates relative to the lowland soils are likely related to extensive vegetation cover which in this context protects soils against erosion and contributes to the formation of organic alpine soils that rapidly accumulate organic matter by comparison to other soil types

quaternary fluvial systems of tropics major issues and status of research abstract fluvial systems in tropical regions are not only the lifeline for modern civilizations there but also form an important continental archive for reconstructing quaternary palaeoclimates and palaeoenvironments tropical rivers drain through a variety of geological and geomorphological settings across the world and have been studied for their hydrology sediment transport characteristics facies models stratigraphic development and flood hazards this paper presents an overview of the research on tropical rivers globally and identifies major gaps and unanswered research questions as a part of the igcp 582 on tropical rivers the participants of this project are continuing to tackle many of these issues the collection of papers in this special issue is an outcome of this activity and presents new data on processes and alluvial stratigraphy of the tropical rivers from china india south america and northern australia

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

quaternary climatic instability in south east australia from a multi proxy speleothem record milankovitch scale quaternary climatic oscillations within south east australia are known to be characterized by relatively arid glacial and wet interglacial stages however terrestrial proxy records of environmental change are scarce based largely on river terraces dune sediments and pollen sequences here we present a speleothem based palaeoclimate record from yarrangobilly caves south east australia the oxygen isotopic composition of calcite 18ocalcite is taken to represent rainfall amount and used as an aridity index high resolution trace element profiles and uv fluorescence support interpretations based on 18ocalcite allowing further designation of key phases of speleothem growth into periods of relative aridity and moisture excess a hiatus of approximately 37 ka duration divides the record into two key phases of growth which can be mapped onto marine isotope stages 5c a and 3 respectively increasing aridity in the latter half of mis 5 led to cessation of speleothem growth for the duration of mis 4 growth recommences during mis 3 associated with greater moisture availability enhanced vegetation and augmented biogeochemical cycling this speleothem record provides a unique context of terrestrial environmental change and depicts hydrological conditions which fluctuate markedly over the 70 ka period covering the time of megafauna extinction and human arrival on the continent

palaeohydrology of lowland rivers in the murray darling basin australia abstract this study derives a new function describing the relationship of channel bankfull discharge qbf to channel width in modern rivers of the murray darling basin mdb of southeastern australia and applies this to dated palaeochannels of seven rivers to quantify late quaternary discharge history in this important basin all rivers show high mis3 and mis2 qbf declining in the holocene the qbf of modern mdb rivers is correlated with total catchment precipitation but comparison with palaeochannel qbf estimates shows that while enhanced runoff efficiency is necessary to account for much larger late pleistocene palaeochannels either lower or higher precipitation rates could have prevailed a strong association between relative palaeo qbf enhancement and temperature suggests a temperature mediated mechanism controlling river discharge such as the fraction of precipitation stored as snow and thawing in spring the enhancement of orographic rainfall or co2 feedbacks with vegetation cover significantly enhanced mis3 qbf requires an additional mechanism such as increased rainfall these findings are consistent with others that increased moisture availability was associated with past colder climates although this was not necessarily the result of enhanced precipitation

aggradation and incision since the very late pleistocene in the naas river south eastern australia past phases of aggradation and incision have been studied along a 10 km reach in the naas valley in south eastern australia detailed mapping of the stratigraphy and an ambitious dating exercise involving 23 optical dates have been used to distinguish the different periods of aggradation and incision the dated alluvial sequence shows that a period of aggradation occurred in the very late pleistocene ca 14 000 12 000 years ago alluvial deposits are absent for the period 12 000 3300 years ago whether this truly reflects no deposition or a series of aggradation and erosion cycles remains unresolved aggradation dominated between 3300 and 900 years ago punctuated by a short incision event around 1300 years ago gully erosion contemporaneous with this incision phase is also recorded incision has dominated during the last 900 years cutting down to bedrock this incision which is still ongoing has not been a continuous process but involved short periods of aggradation the exposed bedrock and large boulders display numerous scour holes indicating that bedrock has been exposed and abraided for lengthy periods in the past the aggradation and incision cycles in the late holocene gave rise to three groups of terraces today visible along the study reach possible causes for the different periods of erosion and deposition are discussed in the context of late pleistocene and holocene climate change land use impacts and intrinsic factors

landslides and residual strength in marl profiles in israel abstract many areas in northern israel show evidence of old landslides in marly profiles and new slides are often activated in these regions such a slide occurred in the town of rechasim near haifa during an exceptionally wet winter in 1992 the present paper analyzes the causes for this slide and suggests that it was due to a combination of downslope flow in the overlying severely cracked chalk limestone layer and mobilization of residual strength at the marl chalk interface the residual strength of israeli marly soils has been studied and it is shown that while many of these consist predominantly of clay sized

tl chronology and stratigraphy of riverine source bordering sand dunes near wagga wagga new south wales australia abstract riverine source bordering dunes are found throughout the murray basin of southeastern australia at the eastern and northern margins of late quaternary palaeochannels the dunes are dominated by locally derived sand but often contain a minor calcareous clay component originating from a distant westerly source in the bedrock confined valley of the murrumbidgee river near wagga wagga the dunes occur as discrete mounds on the floodplain or as drapes over the marginal valley side slopes tl dating of three stratigraphic units within the dunes shows that phases of sand accumulation occurred between 15 and 25 ka in oxygen isotope stage 2 clarendon unit between 35 and 60 ka in stage 3 glenfield unit and between 80 and 120 ka in stage 5 yarragundry unit the tl ages here which show excellent agreement with those determined respectively for the yanco kerarbury and coleambally phases of palaeochannel activity on the riverine plain j quat sci 11 1996 311 extend the emerging regional model of late quaternary climatic and hydrologic change for southeastern australia

climate variability over the last 35 000 years recorded in marine and terrestrial archives in the australian region an oz intimate compilation abstract the australian region spans some 60 of latitude and 50 of longitude and displays considerable regional climate variability both today and during the late quaternary a synthesis of marine and terrestrial climate records combining findings from the southern ocean temperate tropical and arid zones identifies a complex response of climate proxies to a background of changing boundary conditions over the last 35 000 years climate drivers include the seasonal timing of insolation greenhouse gas content of the atmosphere sea level rise and ocean and atmospheric circulation changes our compilation finds few climatic events that could be used to construct a climate event stratigraphy for the entire region limiting the usefulness of this approach instead we have taken a spatial approach looking to discern the patterns of change across the continent the data identify the clearest and most synchronous climatic response at the time of the last glacial maximum lgm 21 3 ka with unambiguous cooling recorded in the ocean and evidence of glaciation in the highlands of tropical new guinea southeast australia and tasmania many terrestrial records suggest drier conditions but with the timing of inferred snowmelt and changes to the rainfall runoff relationships driving higher river discharge at the lgm in contrast the deglaciation is a time of considerable south east to north west variation across the region warming was underway in all regions by 17 ka post glacial sea level rise and its associated regional impacts have played an important role in determining the magnitude and timing of climate response in the north west of the continent in contrast to the southern latitudes no evidence for cooling during the younger dryas chronozone is evident in the region but the antarctic cold reversal clearly occurs south of australia the holocene period is a time of considerable climate variability associated with an intense monsoon in the tropics early in the holocene giving way to a weakened monsoon and an increasingly el nino dominated enso to the present the influence of enso is evident throughout the southeast of australia but not the southwest this climate history provides a template from which to assess the regionality of climate events across australia and make comparisons beyond our region

temperature dependent residual shear strength characteristics of smectite bearing landslide soils this paper presents experimental investigations regarding the effect of temperature on the residual strength of landslide soils at slow to moderate shearing velocities we performed ring shear tests on 23 soil samples at temperatures of 6 29 c the test results show that the shear strength of smectite rich soils decreased when temperatures were relatively low these positive temperature effects strength losses at lower temperatures observed for smectite bearing soils are typical under relatively slow shearing rates in contrast under relatively high shearing rates strength was gained as temperature decreased as rheological properties of smectite suspensions are sensitive to environmental factors such as temperature ph and dissolved ions we inferred that temperature dependent residual strengths of smectitic soils are also attributed to their specific rheological properties visual and sem observations of ca bentonite suggest that slickensided shear surfaces at slow shearing rates are very shiny and smooth whereas those at moderate shearing rates are not glossy and are slightly turbulent indicating that platy smectite particles are strongly orientated at slow velocities the positive temperature effect is probably due to temperature dependent micro friction that is mobilized in the parallel directions of the sheet structure of hydrous smectite particles on the contrary the influence of micro viscous resistance which appears in the vertical directions of the lamination is assumed to increase at faster velocities our results imply that if slip surface soils contain high fractions of smectite decreases in ground temperature can lead to lowered shear resistance of the slip surface and trigger slow landslide movement

topographically associated but chronologically disjunct late quaternary floodplains and terraces in a partly confined valley south eastern australia the bellinger river catchment in the new england fold belt on the mid north coast of new south wales is characterized by an assemblage of stepped late quaternary alluvial units late pleistocene terraces were formed by large more competent rivers that eroded almost entire valley floors however a decline in discharge prior to the holocene has resulted in the abandonment of these deposits as elevated terraces or residual alluvium onlapped by contemporary floodplains intrinsic controls on floodplain formation appear to be superimposed over an early mid holocene climatic signature a fluvially active period known as the nambucca phase from 10 to 4 5 ka eroded late pleistocene terraces two floodplain surfaces one higher than the other both started to accrete vertically from 4 ka but with some valley locations remaining vulnerable to episodes of erosion resulting in substantial units of even younger basal alluvium the high floodplain is dominated by horizontally laminated vertically accreted sequences while the low floodplain which overlaps in age is characterized by pronounced cut and fill stratigraphy terraces and floodplains in partly confined settings can have similar elevations but be polycyclic with very different basal ages in such landscapes the classical assumption that individual terrace or floodplain profiles along a valley represent periods of coeval formation is shown to be frequently invalid copyright 2007 john wiley sons ltd

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

australian dust deposits modern processes and the quaternary record abstract dust raising and transport are common and important processes in australia today the aridity of the australian continent and high climatic variability result in widespread dust raising in the arid and semi arid areas and transport to the humid margins and surrounding oceans the supply of erodible particles appears to be the greatest limitation on total flux of transported dust dust raising is greatest in the lake eyre basin including the simpson desert and murray darling basin where internal drainage renews supplies of fine particles to the arid zone in the west and northwest dust entrainment is low despite considerable aridity the marine record of dust flux shows at least a threefold increase in dust flux compared with the holocene in the last glacial maximum in both tropical and temperate australia driven by weakened australian monsoon rains and drier westerly circulation respectively despite the widespread confirmation of aeolian dust deposits in southeastern and southwestern australia dated or quantified records are extremely rare the dominant model of australian dust deposits the clay rich parna is shown to be poorly substantiated while modern and ancient dust deposits examined in detail are shown to bear a strong similarity to conventional definitions of loess

evidence for regionally wet conditions before the lgm in southeast australia osl ages from a large palaeochannel in the lachlan valley abstract optically stimulated luminescence osl techniques have been used to obtain the rstages on late pleistocene channels in the lachlan valley southeastern australia two osl ages fromchannel sand and overlying source bordering dune sand indicate that large sinuous channels withbankfulldischargessixtoeighttimesgreaterthanthepresentriver werefullyestablishedby34kabp this conclusion is consistent with regional lake level and geomorphic evidence of cool pluvialconditions that preceded the last glacial maximum lgm providing new information on a long standing palaeohydrological problem caused by the apparent synchroneity of large river systems andregional aridity copyright 2007 john wiley sons ltd keywords late quaternary palaeochannels palaeohydrology quartz osl luminescence dating the late pleistocene environmental history of southeasternaustralia relies to a large extent on the relict rivers lakes anddune elds of the riverine plain occupied today by the murrayriver and its tributaries the goulburn murrumbidgee lachlanand darling rivers which rise on the southeastern highlands during the terminal pleistocene the plains supported large actively meandering channels with scrolled oodplains sub stantially larger and carrying coarser sediment loads thanthe irregularly sinuous and muddy present day channels thegoulburn and murrumbidgee palaeochannels have been wellstudied and chronologies based on radiocarbon and thermo luminescence tl suggest two periods of large meanderingchannel activity from 35ka to 25ka and 20ka to 13ka bowler 1978 bowler et al 1978 schumm 1968 page et al 1991 1996 page and nanson 1996 however the regionalchronology does not clearly reveal two synchronous periodsofactivity table1 andisbedevilledbydatinguncertainties forexample suspected contamination of some radiocarbon datesby younger organic compounds contained in the groundwater bowler 1978 was con rmed when kotupna sedimentsradiocarbon dated at 16 13k

late quaternary changes in flow regime on the gwydir distributive fluvial system southeastern australia abstract ages for large palaeochannels of the gwydir distributive fluvial system dfs in northern new south wales australia have been determined using single grain optically stimulated luminescence two palaeochannel systems have been found to dominate the here named coocalla 43 34 ka and kamilaroi 19 16 ka which have inferred palaeodischarges 25 100 times the bankfull discharges of nearby channels of the contemporary gwydir system which appears to have been established during the mid holocene this scale differential is very much larger than that reported for other catchments in southeastern australia and reflects both a decline in catchment runoff through the last glacial cycle and the adoption of a distributary pattern sometime after 16 ka actual decline in catchment runoff determined by comparing estimated palaeodischarge with contemporary flows upstream of the dfs where flow is confined to a single channel indicate contemporary discharge to be 0 1 times and 0 25 times that of the coocalla and kamilaroi respectively the chronology presented here shows periods of increased discharge in the gwydir to be more or less coincident with those observed elsewhere in the murray darling basin although no evidence of a gum creek fluvial phase from 35 to 25 ka was found the coocalla and kamilaroi palaeochannel systems broadly conform in age to kerarbury and yanco fluvial phases on the murrumbidgee and murray systems this synchronicity with more southern catchments supports the hypothesis that la nina like conditions were semi permanent for much of the last glacial cycle with moisture derived largely from the western pacific ocean

palaeomagnetic stratigraphy of lake bungunnia plio pleistocene precursor of aridity in the murray basin southeastern australia abstract the murray darling river system in southeastern australia formerly flowed into a large lake lake bungunnia before reaching the sea fine grained clastics of this system the blanchetown clay formation extend over an area of about 68 000 km2 underlying the mallee region with its surface array of dunes and salt lakes palaeomagnetic analyses are used to date the major hydrologic transition from the expansive freshwater system to the saline deflation playas and dunes that characterize this landscape today two sites were selected for sampling one a cliff section on the left bank of the murray river at chowilla the other from within sediments of lake tyrrell a saline playa cut into sediments of the older freshwater system two sequences were sampled at tyrrell one by coring to 30 m in the basin centre the other a composite cliff and 5 m core on the western margin of the playa post bungunnia sediments representing modern landforms were sampled in both surficial dune palaeosol units of the woorinen formation and in saline sediments the tyrrell beds within the modern saline playa the sequence of multiple aeolian units of the woorinen formation and gypseous sediments of the tyrrell beds are normally magnetized indicating deposition within the past 0 7 million years by contrast the uppermost horizons of bedded blanchetown clay below a surface zone of pedogenic alteration are reversed the brunhes matuyama b m boundary key to the age of draining of lake bungunnia by deepening the overflow channel to the sea is obscured within the zone of pedogenesis separating unaltered blanchetown clays from overlying aeolian deposits the onset of aeolian and saline gypseous deposits characteristic of the arid zone facies is placed soon after the b m boundary about 500 000 years ago sequences through the blanchetown clay pass down through the matuyama reversed chron into the gauss normal chron with the lowermost section on the tyrrell west bank recording a basal reversed zone of possible gilbert age thus the origins of lake bungunnia extend back beyond basal pleistocene into the late pliocene the lake s duration covers more than 2 million years spanning the plio pleistocene boundary in this important region of southeastern australia

dry lake beds as sources of dust in australia during the late quaternary a volumetric approach based on lake bed and deflated dune volumes abstract dust affects earth s climate ecology and economies across a broad range of scales both temporally and spatially and is an integral part of the earth s climate system previous studies have highlighted the importance of inland lake beds to dust emissions both locally and globally this study aims to explore the relative volumetric importance of ephemeral lakes that emit dust to the australian southeastern dust path over the last glacial cycle srtm dems and gis analyses of long term up to 80 ka lake bed deflation volumes and deposition of sand sized sediment onto downwind source bordering dunes were used to derive estimates of transported dust mass a strong power relationship was found between lake area and the mass of deflated lake bed sediments total dust masses for the largest 53 lakes in southeastern australia were derived using the relationship between lake area and dust mass and used to determine an upper value for total dust mass deflated from lake beds in southeastern australia ephemeral lake derived dust was found to represent at most 13 of the dust derived from southeastern australia deposited in the southern pacific over the last 80 ka or 22 over the last 40 ka lake eyre the largest lake has contributed at most 3 of the australian southeast dust plume these results imply that there are significant additional sources of dust in australia over these timescales such as floodplains or dunefields and that modelling must allow for diverse climatic and geomorphic controls on dust production

evolution of sedimentary basins simple extensional models that involve stretching by listric faulting in the brittle upper crust and plastic flow in the lower lithosphere have been shown to account for the subsidence history of various sedimentary basins continental shelves and the central graben in the north sea in this paper the authors present a simplified analysis of the two layer extensional model for the elementary case in which extension is instantaneous the crust is thinned by a different amount from the subcrustal lithosphere the effects of radioactivity and dike intrusion are ignored and local isostatic compensation is assumed at all times the authors show how the thinning parameters can be obtained from the subsidence data through the use of a simple and powerful method of data analysis the authors show that conservation of mass during a process of non uniform extension implies that much greater thicknesses of sediment can be deposited in a young basin than in the case of uniform extension of both crust and subcrustal lithosphere further the authors show that such an extensional process produces significant uplift of the flanks of a graben and that as a result of erosion of the uplifted areas the effective area of the basin can be more increased as much as 25 to 30 depending on the rate of erosion compared to the area that would have been created by a process of uniform extension finally the authors consider the forces of uplift on the flanks in the situation where the crust is treated as a thin elastic plate floating on a fluid upper mantle the graben is bounded by two major normal faults and there is subcrustal thinning under the flanks the authors show that such normal faults produce uplift of the flanks and that this uplift can be significantly increased by the subcrustal thinning less

climatic and vegetation control on sediment dynamics during the last glacial cycle as climate is changing rapidly there is an increasing need to understand how water and soil resources respond to climate change soil and sediment dynamics are sensitive to several external factors such as climate vegetation type and distribution human activity and tectonic activity however the relationship between erosion and changes in these factors is difficult to constrain with current available approaches here we show that uranium isotopes in sediments from river paleochannels can be used to reconstruct variations in the residence time of sediments in a catchment over the past 100 k y we find that sediment residence times increase by an order of magnitude during interglacials compared to glacial periods this is interpreted as a change in sediment stores in the landscape that are tapped by catchment erosion young upland soils during glacial periods reworking of old alluvial sediments during interglacials a direct correlation is found between the sediment residence time and climatic parameters sea surface temperature atmospheric carbon dioxide content and paleorainfall estimates suggesting that during a glacial cycle sediment dynamics closely follow variations in climate however this relationship is not simple because there is no correlation between sediment residence time and paleodischarge estimates because sediment residence time variations correlate with changes in vegetation inferred from pollen data it is hypothesized that the influence of climate on erosion over a glacial cycle may be indirect and operates via the influence of climate on the type of plant ecosystems within a catchment if verified elsewhere this conclusion would emphasize the important role of biology in the physical evolution of earth s surface here observed over a 100 k y time scale

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

alluvium of antiquity polycyclic terraces in a confined bedrock valley confined river valleys are not the localities where long term preservation of alluvium would be expected the 25 km long low gradient 0 0014 m m 1 confined valley setting of the shoalhaven river has archived alluvium of middle pleistocene age to maintain a relatively uniform channel as an efficient conduit for a wide range of flows in a confined bedrock valley of variable morphology single grain optically stimulated luminescence osl dating has identified polycyclic terraces up to 193 ka in age marine isotope stage mis 7 with lower terrace remnants dating from 173 140 ka mis 6 and 106 ka mis 5 holocene alluvium 2 3 5 ka in age caps these old pleistocene units and a well constrained combination of one dimensional and two dimensional hydraulic modelling demonstrates that these polycyclic terraces are clearly within reach of the modern hydrological regime the 106 ka terrace at 17 m above low flow is inundated by floods recurring on average every 20 years and the 140 193 ka terraces at 20 22 m are overtopped every 50 100 years these ancient diachronous landforms exhibit complex depositional histories and are on lapped by longitudinal benches of modern sand and gravel their polycyclic nature appears to be a response to flow reduction using alluvium to adjust the boundary of the otherwise inflexible morphology of a bedrock gorge

the residual shear strength of tropical soils the paper discusses the residual shear strength of tropical soils ring shear tests have been performed with tropical soils from southern brazil using the bromhead apparatus the data from the study are compared with data obtained in a comprehensive literature review of the subject the residual friction angle of tropical residual soils from sedimentary formations decreases with increasing plasticity index following a general trend presented in the literature most of the residual soils described herein have also shown this trend however some of these residual soils particularly basalt saprolitic soils have shown quite low residual friction angles despite having low plasticity index and clay fraction values it has been confirmed that the residual shear strength of tropical soils depends chiefly on mineralogy particle size distribution effective stress parent rock weathering degree pedogenetic evolution and when partly weathered minerals are present degradation upon shearing the substantial

wetting and drying of australia over the past 300 ka alternately dry and wet climatic episodes across central and eastern australia during the past 300 ka have greatly affected australia9s rivers lakes and dune fields evidence of widespread climate and flow regime changes has been provided by 75 thermoluminescence tl dates and 18 u th dates from alluvial and eolian sediments fluvial conditions dominated part of the last two interglacials stage 5 and 7 resulting in large sand loads in rivers in the present simpson desert and southeastern australia during the last interglacial fluvial activity in central australia peaked at 110 ka stage 5 pluvial probably 5 10 ka behind world temperature and sea level maxima following the last late interglacial wet phase aridity associated with dune building spread from central australia toward its margins achieving greatest intensity during the last glacial maximum a less widespread wet phase identified at about 55 35 ka stage 3 subpluvial is associated with high lake levels and paleochannel activity in southeastern australia this tl record of variable continental aridity in australia correlates well with global changes including the variable eolian dust flux into central china the northern pacific ocean and antarctica

lake bungunnia a plio pleistocene megalake in southern australia abstract between 2 5 ma and 0 7 ma a plio pleistocene megalake lake bungunnia existed in the western murray basin australia study of hydrologic and geologic constraints on this lake has enabled the climate of southeastern australia during the late pliocene and early pleistocene to be partly quantified modelling shows that lake bungunnia could not exist under current climatic conditions and that an average rainfall of at least 500 mm yr 1 over the catchment of the murray darling river system was likely considerably more than at present minor changes in climate caused large fluctuations in the shoreline of the shallow lake which are reflected in the geologic record possible histories for lake bungunnia are suggested in the light of this evidence demise of the megalake heralded the onset of aridity in southern australia and modern landforms date from that time salt lakes in part of the western murray basin may have directly descended from lake bungunnia

the thermal blanketing effect of sediments on the rate and amount of subsidence in sedimentary basins formed by extension abstract the thermal blanketing effect of sediments with finite thermal conductivity on the rate and amount of subsidence in rift basins is presented in contrast with mckenzie s 1978 model which assumed infinite thermal conductivity of the sedimentary covers the post rift cooling of the lithosphere is shown to be very slow owing to the blanketing effect even 200 m y after extension ceases there is still an enormous amount of residual heat in the lithosphere with moderate thermal conductivity of the sediments k s 2 0 w mk the maximum discrepancy in subsidence predicted by the two models i e the present model and that of mckenzie are 2 km 2 6 km and 3 2 km for thinning factors of 1 5 2 and 3 respectively subsidence is moderately sensitive to k s when k s is greater than 2 0 w mk becoming more sensitive to k s when k s is less than 2 0 w mk the presence of mudstone would further slow down the cooling the thermal conductivity of the sediment is shown to govern the temperature gradient of rift basins although it has little influence on heat flow the heat production of the upper crust and sediment comprises an important component of heat flow unless heat absorption in rift basins is unusually high subsidence is insensitive to the heat production of sediments when the thinning factor is less than 2 the mean temperature gradient of rift basins is shown to decrease quickly over a few million years and as a result such basins are not favourable as regards hydrocarbon maturity the central graben of the north sea is chosen to test the model the model satisfactorily predicts the subsidence history and thermal evolution with the base zechstein as the basement and the cenozoic subsidence as the thermal subsidence the best fit value of the mean thermal conductivity of the sediments in the graben is 1 67 w mk and the thinning factor is about 2

a high resolution late quaternary depositional history and chronology for the southern portion of the lake mungo lunette semi arid australia abstract the willandra lakes region sits on the southern margin of australia s arid core and is one of the oldest localities on the continent known to have been occupied by australia s first people the archaeological traces that accumulated in the lake mungo lunette paint a picture of changing land use over the past 50 thousand years ka and some of these are likely to have been responses to changes in palaeoenvironmental conditions this study set out to determine the finest temporal resolution that can be used to study the depositional and palaeoenvironmental history of the lake mungo lunette the investigation focused on the depositional history documented within stratigraphy exposed in an eroding gully in the southern part of the lunette gully 10 a stratigraphic framework was developed using sedimentological and soil micromorphological analysis this framework was then fixed in time by 56 single grain optically stimulated luminescence osl age estimates these data sets were then combined into a bayesian model that indicated three depositional phases 100 ka lu1 65 33 ka lu2 lu3 and from 30 to 16 ka lu4 lu9 with the late pleistocene and holocene samples lu10 11 not being modelled furthermore the redating of thirteen lower and upper mungo osl samples from bowler et al 2003 s study of the southern tip of the lunette yielded younger age estimates for twelve of these bringing them into line with previously published independent age control as well as the ages presented in this study this study provides an approach for future efforts to establish consistency in age estimation and palaeoenvironmental interpretation along the length of the lunette

climate of the last glaciation in new zealand based on aerosolic quartz influx in an andesitic terrain abstract on western north island new zealand a record of climatic change during the last glaciation is preserved in a terrestrial coverbed sequence of dominantly andesitic provenance here a succession of five loess like andisol units postdates the global high sea level stand of oxygen isotope substage 5e

glacial and deglacial climatic patterns in australia and surrounding regions from 35 000 to 10 000 years ago reconstructed from terrestrial and near shore proxy data abstract this study forms part of a wider investigation of late quaternary environments in the southern hemisphere we here review the terrestrial and near shore proxy data from australia indonesia papua new guinea png new zealand and surrounding oceans during 35 10 ka an interval spanning the lead up to the last glacial maximum lgm the lgm proper 21 2 ka and the ensuing deglaciation sites selected for detailed discussion have a continuous or near continuous sedimentary record for this time interval a stratigraphically consistent chronology and one or more sources of proxy climatic data tropical australia indonesia and png had lgm mean annual temperatures 3 7 c below present values and summer precipitation reduced by at least 30 consistent with a weaker summer monsoon and a northward displacement of the intertropical convergence zone the summer monsoon was re established in northwest australia by 14 ka precipitation in northeast australia was reduced to less than 50 of present values until warmer and wetter conditions resumed at 17 16 ka followed by a second warmer wetter phase at 15 14 ka lgm temperatures were up to 8 c lower than today in mainland southeast australia and up to 4 c cooler in tasmania winter rainfall was much reduced throughout much of southern australia although periodic extreme flood events are evident in the fluvial record glacial advances in southeast australia are dated to 32 2 5 19 1 1 6 and 16 8 1 4 ka with periglacial activity concentrated towards 23 16 ka deglaciation was rapid in the snowy mountains which were ice free by 15 8 ka minimum effective precipitation in southern australia was from 14 to 12 ka in new zealand the glacial advances date to 28 21 5 and 19 ka with the onset of major cooling at 28 ka or well before the lgm there is no convincing evidence for a younger dryas cooling event in or around new zealand but there are signs of the antarctic cold reversal in and around new zealand and off southern australia there remain unresolved discrepancies between the climates inferred from pollen and those inferred from the beetle and chironomid fauna at a number of new zealand sites one explanation may be that pollen provides a generalised regional climatic signal in contrast to the finer local resolution offered by beetles and chironomids sea surface temperatures ssts were up to 5 c cooler during the lgm with rapid warming after 20 ka to attain present values by 15 ka the increase in summer monsoonal precipitation at or before 15 ka reflects higher insolation warmer ssts and steeper thermal gradients between land and sea the postglacial increase in winter rainfall in southern australia is probably related to the southward displacement of the westerlies as ssts around antarctica became warmer and the winter pack ice and antarctic convergence zone retreated to the south

shear wave velocity drop prior to clayey mass movement in laboratory flume experiments abstract clay slopes are susceptible to suddenly liquefy into rapidly accelerating landslides thereby threatening people and facilities in mountainous areas because the shear wave velocity v s characterizes the medium stiffness this parameter can potentially be used to investigate the rheological behavior of clay materials before and during the solid to fluid transition associated to such landslide failures previous rheometrical studies performed on clay samples coming from trieves landslides french alps have established that this material behaves as a yield stress fluid with a marked viscosity bifurcation when the applied stress reaches a critical level the viscosity decreases abruptly along with v s which tends to zero in the fully fluidized material here we monitor the rayleigh wave velocity v r variations in a saturated clay layer placed in a flume and progressively brought to failure by tilting the device experiments performed on clay samples with different water contents show a significant relative drop in v r values and hence in v s before the onset of the mass movement additional rheometrical analyses point out that this precursory drop in v s is presumably due to a complex transient rheological response of the clay these new results confirm that v s variations constitute a good indicator for monitoring clay slope stability

how did rivers in the wet tropics ne queensland australia respond to climate changes over the past 30 000 years the nature and timing of fluvial response and coincident changes in climate as inferred from multiple independent proxies are examined in the wet tropics of north eastern australia chronostratigraphic data provide evidence for regionally synchronous fluvial aggradation at 30 13 ka 8 5 ka and again from 1 ka terrace incision and removal occurred at 13 8 ka and 5 1 ka a new synthesis of regional palaeoenvironmental proxy records spanning the last 30 ka highlights key periods of environmental change comparison of the records of fluvial and environmental change reveals the relationship is complex with no clear relationship between river aggradation incision and wetter drier conditions the nature and timing of fluvial response in the wet tropics also shows broad similarities with coastal valleys in south eastern new south wales suggesting continental scale controls on fluvial response to changing climate during the late quaternary in australia copyright c 2017 john wiley sons ltd

mind the gap an absence of valley fill deposits identifying the holocene hypsithermal period of enhanced flow regime in southeastern australia the holocene sedimentary record in southeastern australia is present in a range of landscape settings such as upland swamps dells internally drained lake basins alluvial fans and mid catchmen

lacustrine fluvial interactions in australia s riverine plains climatic forcing of fluvial systems has been a pre occupation of geomorphological studies in australia since the 1940s in the riverine plain southeastern australia the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world surficial sediments and landforms exceed 140 000 yr in age and geomorphological change recorded in the fluvial fluvio lacustrine and aeolian features have provided a well studied record of quaternary environmental change over the last glacial cycle the region includes the willandra lakes whose distinctive lunette lakes preserve a history of water level variations and ecological change that is the cornerstone of australian quaternary chronostratigraphy the lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the australian continent to date the lake level and palaeochannel records in the lachlan willandra system have not been fully integrated making it difficult to establish the regional significance of hydrological change here we compare the willandra lakes environmental record with the morphology and location of fluvial systems in the lower lachlan an ancient channel belt of the lachlan willandra creek acted as the main feeder channel to willandra lakes before channel avulsion caused the lakes to dry out in the late pleistocene electromagnetic surveys geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion single grain optical dating of floodplain sediments indicates that sedimentation in the new middle billabong palaeochannel had commenced before 18 4 1 1 ka a second avulsion shifted its upper reaches to the location of the present lachlan river by 16 2 0 9 ka the timing of these events is consistent with palaeohydrological records reconstructed from willandra lakes and with the record of palaeochannels on the lachlan river upstream willandra lakes shows high inflows during the last glacial maximum 22 ka but their subsequent drying between 20 5 ka and 19 ka was caused by river avulsion rather than regional aridity this case study highlights the benefits of combining fluvial with lacustrine archives to build complementary records of hydrological change in lowland riverine plains

an evaluation of australia as a major source of dust abstract since australia is the driest inhabited continent it is a natural laboratory to study on a large scale dust its composition its sources transport and geochemical composition this is necessary as there has been a lack of appreciation of the diversity of the australian regolith characterized by a great array of ages and compositions this is particularly true of studies that examined the geochemistry of australian dusts and links with potential deposition sites such as in antarctica and comparison with south america hence the first part of this paper provides an overview of the surficial geology of australia with emphasis on regions from where dust can become deflated a review follows on the investigations of significant dust transport and events in australia the second part of the paper provides a review of the sites of potential deflation of dust it includes the study of different geomorphological sites of dust deflation with a discussion on how dust particles can accumulate in regions linked to large playa lakes that are under the influence of groundwater below them this is an important mode of dust deflation a process of which had insufficiently been detailed before the processes involving evaporative pumping are explained and several illustrations are provided to document those processes and location of dust deposits another region of importance to dust deflation consists of extensive alluvial plains and these are also documented with an area in the upper reaches of the darling river being now documented more fully finally the inter dunal corridors in large dune fields are also mentioned as a source of dust as previous studies already show this second part ends with the description of the two main potential source areas psa of dust in australia and these are the kati thanda lake eyre region of central australia and the darling riverine plain in the upper reaches of the darling river these two regions are important for their geochemical fingerprints for transcontinental studies and supported by satellite imagery that identify dust plumes originating from these regions the third part of the paper examines the geochemical composition of australian psas by paying particular attention to neodymium strontium and lead isotopic ratios from both continents we also suggest the possibility of combining nd and pb isotopes as a way of fingerprinting geochemically between different australian regions and for comparison with other continental psas this part also reviews previous studies that aimed at geochemically fingerprinting the australian regolith by referring also how these studies were applied to reconstruct past environmental conditions

residual strength of slip zones of large landslides in the three gorges area china abstract slip zones of the large landslides in the three gorges area are commonly composed of fine grained soils with substantial amount of coarse grained particles particularly gravel sized particles in this study residual strength of the soils from slip zones of these landslides were examined in relation to their index properties based on a survey of 170 landslides it was found that laboratory determined residual friction angle using gravel free fraction of the disturbed soils from the slip zones was closely related to clay content liquid limit and plasticity index on the other hand in situ residual friction angle of these soils i e including gravel fraction showed very weak correlations with clay content and atterberg limits but was largely dependent on gravel and fines clays silts contents increasing with gravels and decreasing with fines and displayed strong linear correlation with the ratio of gravel to fines contents these observations indicate that among the index properties clay content and atterberg limits can be used to estimate residual strength of the soils finer than 2 mm but they are not appropriate evaluate the residual strength of the soils containing considerable amount of gravel sized particles for the latter particle size distribution particularly the ratio of gravel to fines contents appears to be a useful index additionally it was found that there was no identifiable correlation between relative abundance of individual major clay minerals and residual friction angles of both gravel free fraction of disturbed and in situ soils suggesting that influence of clay minerals on residual strength of these soils can not be simply evaluated based on their abundance

development of stabilisation and solidification in lime clay mixes two refined clay minerals english china clay predominantly kaolinite and wyoming bentonite predominantly sodium montmorillonite were used to assess the time dependent effects of mineral structural chemistry on the lime clay reaction the two clays representing the extremes of structural negative charge development were treated with two lime contents changes in the physico chemistry of the samples were monitored after three curing periods by performing batch leaching tests and monitoring changes in undrained shear strength and atterberg limits the effects of changing the batch test operating parameters and increasing the curing period were assessed by measuring changes in solution ph and conductivity and by analysis of eight elements in solution the solidification mechanisms due to lime addition were found to be different for the two minerals pozzolanic reactions involving english china clay and wyoming bentonite were found to occur owing to the dissolution of aluminium and silicon from the re

influence of lixiviation by irrigation water on residual shear strength of weathered red mudstone in northwest china implication for its role in landslides reactivation abstract irrigation in loess tableland areas of northwest china has induced a large number of landslides around their edges of which loess red mudstone landslide is one of the most frequent types salt sinters commonly observed at the toes of these landslides where the weathered red mudstone wrm outcrops have raised the possibility that removal of soluble salts in the wrm by irrigation water could be crucial in the reduction of its shear strength and thus in the occurrence of these landslides in order to investigate the effects of lixiviation by irrigation water on residual shear strength of the wrm samples of the wrm close to two landslides in lanzhou city one of the largest cities in northwest china were tested after being treated under different conditions these included 1 saturation with the yellow river water the only source of irrigation 2 saturation with groundwater and 3 saturation and leaching with deionized water based on the results of these tests specific mechanisms of residual shear strength reduction of the wrm due to lixiviation by irrigation water were discussed in terms of physico chemical interactions between the wrm and water it was found that lixiviation reduced residual shear strength and residual friction angle r of the wrm by up to 65 and 62 respectively after being leached 6 times this coincided with a dramatic dissolution and leaching of soluble salts from the wrm particle size distribution showed that the more the wrm was leached the more the clay fraction and the lesser coarser fractions this suggested that reduction in residual shear strength of the wrm could be attributed to mainly disaggregation of particles coarser than clay and to a lesser degree to weakening of interparticle forces among individual clays it was further postulated that variation in clay mineralogy may influence performance of particle disaggregation

stratigraphic architecture resulting from late quaternary evolution of the riverine plain south eastern australia the riverine plain of south eastern australia is the result of prolonged cenozoic fluvial activity single thread anabranching and distributary channels and floodplains and associated aeolian dunes characterize the uppermost sequences based on detailed interpretations of late quaternary fluvial sedimentation and surficial stratigraphy for this 77 000 km2 basin earlier prior stream and ancestral stream models of fluvial deposition deduced from limited stratigraphic and chronological evidence are replaced with aggradational palaeochannel and migrational palaeochannel models thermoluminescence dating reveals four distinct phases of palaeochannel activity between 105 and 12 ka the first coleambally phase late in oxygen isotope stage 5 the second kerarbury phase in stage 3 the third gum creek phase before and the fourth yanco phase after the last glacial maximum lgm in stage 2 the first three of these phases were characterized by mixed load laterally migrating sinuous palaeochannels with occasional transitions to a straighter bedload dominated mode and vice versa the first two phases concluded with a bedload dominated episode resulting in aggradational palaeochannels on the surface of the plain and the third phase prior to the lgm did also in its downstream reaches the phase following the lgm was characterized entirely by large mixed load sinuous migrational palaeochannels these exhibited no terminating bedload episode because the onset of holocene climates reduced the size of the flood peaks greatly diminished the supply of bedload from the upper catchments and resulted in streams evolving to their present highly sinuous suspended load form the result is a complex stratigraphic architecture consisting of vertically and laterally accreted units extending over hundreds of kilometres in the form of channel sand stringers sand sheets and derivative aeolian dunes partially or wholly encased in overbank fines

geology geomorphology and dynamics of the 15 february 2010 maierato landslide calabria italy abstract on 15 february 2010 as a result of intense and long lasting rainfalls a large landslide affected a wide area near the town of maierato calabria italy the studies conducted including i aerial photo interpretation ii geological and geomorphological field investigations iii interpretations of lithology and stratigraphy from borehole data and iv observation of videos filmed during the main diastrophic phases of the landslide and of antecedent google street view images allowed researchers to reconstruct the geological and tectonic setting of the slope and the internal structure of the landslide with the estimation of the depth of the sliding surface the triggering mechanisms and its evolution the analysis of the prelandslide event setting demonstrates that this mass movement is the reactivation of a preexisting landslide of alleged seismic origin remaining at an incipient stage the maierato landslide occurred on a gentle slope made of late miocene to plio pleistocene clastic and evaporitic sedimentary rocks the main basal failure surface that developed on the hemipelagic marls has a maximum depth of 50 m the volume of the landslide is 5 million cubic meters the type of landslide movement is a complex one consisting of a very rapid slide of rock and earth and of flow of debris and earth the landslide clearly shows three major types of failure mechanisms the first type is described as a rapidly moving rotational slide where back tilted blocks of sediment are preserved the second type includes a very rapidly moving translational slide of large rock blocks the third type includes sudden extremely rapid flow slides where the slide material is disaggregated while flowing downward along a gentle slope the slide is a compound one with a retrogressive evolution and transformation into earth and debris flow during the failure after the triggering of the landslide and as a result of the relevant displacement an important portion of the lower evaporitic unit calcare di base formation close to the failure surface collapsed thereby undergoing a quick change of its mechanical behavior that became similar to that of a viscous fluid during the landslide evolution large rocky blocks consisting of miocene evaporitic limestones pliocene silty clays and sands were rafted without severe disturbance on the destructurated and fluidized limestone the intense destructuration and the presence of water transformed the limestone in the lower parts of the unit into a viscous material that was squeezed out of the landslide mass through the jags between the several rafted rocky blocks and along the natural levees of flow tongue this event is a rather frequent combination of mass movements made complicated and spectacular by the fluidization of the weak limestone that imparted great dynamics to the movements such fluidization is an infrequent phenomenon especially in this geological context

aeolian fluvial interaction and climate change source bordering dune development over the past 100 ka on cooper creek central australia abstract this study provides an interpretation of interrelated quaternary fluvial and aeolian activity related to climate change on cooper creek in the lake eyre basin in southwestern queensland central australia the extensive muddy floodplain is characterised by buried sandy palaeochannels now almost entirely invisible but stratigraphically connected to source bordering dunes that emerge as distinctive sandy islands through the floodplain surface luminescence dating has identified pronounced periods of fluvial activity represented by abundant sandy alluvium from marine isotope stages mis 8 3 while all these sandy fluvial episodes on cooper creek were much more powerful than anything subsequent they appear to be ranked in order of declining activity mis 8 6 saw reworking of almost the entire floodplain whereas subsequent phases of reworking were far less extensive source bordering dunes were derived from active sandy channels in late mis 5 85 80 ka and mid mis 3 50 40 ka after 40 ka sand channel activity largely ceased and the floodplains and channels were inundated with mud isolating the dunes as emergent features although aeolian reworking of the upper parts of some dunes has continued to the present they show remarkable resilience having survived without appreciable migration for at least 40 ka whilst the channels once determined the location of source bordering dunes in an interesting role reversal the remnant dunes now determine the position of many contemporary flood channels and waterholes by deflection and confinement of overbank flows

episodic fluvial activity of inland rivers in southeastern australia palaeochannel systems and terraces of the lachlan river inland rivers in southeastern australia preserve a long record of surface palaeochannels accompanied by alluvial terraces that reflect changes in water and sediment discharges from the southeastern highlands through much of the last glacial cycle a compilation of ages on rivers of the southern murray darling basin together with new dates from the lachlan river suggest that the fluvial response to climate change has been regionally consistent and responsive to climate change on timescales 10 ka for much of the last glacial cycle inland rivers were mixed load sinuous single and anabranching channels that carried bankfull discharges of between 3 and 11 times present day rivers incision of the upper alluvial plains and valleys occurred in the lead up to the coldest part of the last glacial cycle this was followed at 34 ka by the synchronous development of large meandering channels that may have been associated with lower evapotranspiration from alpine highland catchments accompanied by higher precipitation smaller channels and declining lateral channel sedimentation suggests arid climates during the last glacial maximum and late glacial period with seasonally large actively migrating channels being maintained in rivers dominated by snowmelt runoff from the australian alps during the holocene sensitivity to recorded changes in precipitation amounts and variability differed between catchments with some rivers constructing larger or more actively migrating channels in the early to mid holocene

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

residual shear strength measured by laboratory tests and mobilized in landslides drained residual shear strength measured by multiple reversal direct shear or ring shear tests has been successfully used for over four decades for stability analyses of reactivated landslides in stiff clays and clay shales a body of literature has accumulated in recent decades claiming that healing or strength regain is realized in time on preexisting slip surfaces already at residual condition in other words the shear stress required to reactivate a landslide is claimed to be larger than the drained residual shear strength determined using laboratory tests this article presents 1 a comparison of secant residual friction angle determined from laboratory tests and secant mobilized friction angle back calculated for reactivated landslides 2 explanations that field evidence used to claim healing can be attributed to alternative factors and the laboratory evidence on strength regain upon reshearing is the result of either the testing apparatus or testing procedure or is inapplicable to stiff clays and shales and 3 laboratory aging test results which show no strength regain on preexisting shear surfaces at residual condition doi 10 1061 asce gt 1943 5606 0000624 2012 american society of civil engineers ce database subject headings clays shale residual strength landslides slope stability laboratory tests author keywords clays shales residual strength landslides slope stability

chronology of murrumbidgee river palaeochannels on the riverine plain southeastern australia four major periods of palaeochannel activity have been identified on the murrumbidgee sector of the riverine plain of southeastern australia on the basis of stratigraphic information the channels reveal a picture of changing flow conditions during the last full glacial cycle the ages of the periods were determined from nearly 40 thermoluminescence dates on surficial fluvial and aeolian sediments these are named the coleambally phase which occurred from 105 to 80 ka the mid to latter part of oxygen isotope stage 5 the kerarbury phase from 55 to 35 ka stage 3 the gum creek phase from 35 to 25 ka late stage 3 to early stage 2 and the yanco phase from 20 to 13 ka late stage 2 the present flow regime was established by about 12 ka stage 1 the first two phases correlate with episodes of enhanced fluvial activity in northern and central australia and with reduced dust activity globally the phases in stage 2 appear to be associated with seasonal snow melt and increased peak flows in periods flanking the last glacial maximum source bordering aeolian dunes associated with the coleambally kerarbury and yanco phases were found however the tl dates show that some have undergone aeolian reworking thermoluminescence dating and fluvial stratigraphy have revealed a detailed picture of late quaternary climate and flow regime changes that has the potential to extend to identified deposits stratigraphically older than those described here