fossils from quaternary fluvial archives sources of biostratigraphical biogeographical and palaeoclimatic evidence fluvial sedimentary archives have the potential to preserve a wide variety of palaeontological evidence ranging from robust bones and teeth found in coarse gravel aggradations to delicate insect remains and plant macrofossils from fine grained deposits over the last decade advances in quaternary biostratigraphy based on vertebrate and invertebrate fossils primarily mammals and molluscs have been made in many parts of the world resulting in improved relative chronologies for fluviatile sequences complementary fossil groups such as insects ostracods and plant macrofossils are also increasingly used in multi proxy palaeoclimatic and palaeoenvironmental reconstructions allowing direct comparison of the climates and environments that prevailed at different times across widely separated regions this paper reviews these topics on a regional basis with an emphasis on the latest published information and represents an update to the 2007 review compiled by the flag inspired igcp 449 biostratigraphy subgroup disparities in the level of detail available for different regions can largely be attributed to varying potential for preservation of fossil material which is especially poor in areas of non calcareous bedrock but to some extent also reflect research priorities in different parts of the world recognition of the value of biostratigraphical and palaeoclimatic frameworks which have been refined over many decades in the core regions for such research particularly for the late middle and late pleistocene of nw europe has focussed attention on the need to accumulate similar palaeontological datasets in areas lacking such long research histories although the emerging datasets from these understudied regions currently allow only tentative conclusions to be drawn they represent an important stage in the development of independent biostratigraphical and palaeoenvironmental schemes which can then be compared and contrasted

coarse grained sediment gravity flow facies in a large supraglacial lake near williams lake in the central interior of british columbia the fraser river exposes long sections of late pleistocene glaciolacustrine sediments selectively preserved within a bedrock trough the dominant facies types are thick normally graded gravels and sands that occupy steeply dipping multistorey channels up to 300 m wide and several tens of metres deep channels appear to have been simultaneously cut and filled by high density turbidity currents in a glacial lake floored by stagnant ice fining upward sediment gravity flow sequences up to 50 m thick may be the product of quasi continuous surging turbidity flows triggered by catastrophic meltwater discharges into the trough or retrogressive failure of ice cored sediments large scale post depositional deformation structures such as synclinal folds normal faults sedimentary dyke swarms and dewatering structures record gravitational foundering of sediment and pore water expulsion caused by the melt of underlying glacier ice melting of buried ice masses along the floor of the trough appears to have controlled the flow paths of turbidity currents by producing sub basins within the overlying sediment pile an idealized model of supraglacial lacustrine sedimentation is developed that may be applicable to other glaciated areas with similar bedrock topography

the late devensian 22 000 bp irish sea basin the sedimentary record of a collapsed ice sheet margin the late devensian 20 ka bp glacial geology of the irish sea basin 4000 km2 is an event stratigraphy recording the entry of marine waters into a glacio isostatically depressed basin and the rapid retreat of the irish sea glacier as a tidewater ice margin marine limits occur up to 140 m o d across much of the central basin the ice margin was uncoupled from its bed exposing a subglacially scoured topography to glaciomarine processes the irish sea glacier was a major drainage conduit of the last british ice sheet calving of the marine ice margin resulted in fast flow surging of ice streams recorded by drumlin fields around the northern basin margin and tunnel valleys rapid evacuation of the basin may have stranded large areas of dead ice in peripheral zones e g cheshire shropshire lowlands and initiated the collapse of the ice sheet thick wedges of ice contact glaciomarine sediments were deposited during ice retreat as morainal bank complexes by successive tidewater ice margins stabilized at pinning points around the irish sea coast where morainal banks occur on the seaward side of drumlin swarms there is a clear sequential relationship between rapid ice loss from calving ice margins the development of fast flowing ice streams drumlinization and the pumping of subglacial sediment to tidewater raised delta complexes are locally associated with marine limits along the high relief coastal margins of wales east central ireland and the lake district associated valley infill complexes record downslope resedimentation of heterogenous sediments into the marine environment during ice retreat co eval offshore deposits are represented by well stratified glaciomarine complexes that infill a subglacially scoured topography that shows networks of tunnel valleys glaciomarine mud drapes occur well to the south of the maximum limit of grounded ice in the basin e g north devon scilly islands southern ireland the age of these distal sediments previously mapped as pre devensian tills is constrained by amino acid ratios basin rebound following deglaciation was rapid with over 100 m recovery in 3 ka and was followed by a low marine still stand peat accumulating in offshore areas now as much as 55 m below sea level has been drowned by the postglacial eustatic rise in sea level the glacio sedimentary model identified in this paper involving rapid ice retreat and related sedimentation triggered by rising relative sea level suggests that isotatic downwarping is an important mechanism for deglaciating continental shelves

use of a viscous model of till rheology to describe gravitational loading instabilities in glacial sediments this paper models the operation of loading rayleigh taylor instabilities in sediments using an effective pressure dependent viscosity such has been used to model the deformation of sediment beneath glaciers a particular feature is a strong increase of viscosity with depth resulting from the fact that the effective pressure increases with depth observations suggest that more than one wavelength is generally present e g diapirism and loadcasting which requires at least three layers with uniform properties to be present three layers permit wavelength growth maxima at two distinct wavelengths we investigate whether an effective pressure dependent rheology is consistent with rt instabilities and whether the non uniformity it produces is able to increase the number of growth rate maxima the investigation starts from the point where sediment in an underlying layer is less dense than the overlying sediment and the rayleigh taylor instability starts to operate the mechanics of two layers of finite thickness but infinite extent are modelled by the stokes equations the equation set is linearized and the fourier transform taken in order to describe the periodic horizontal variation of flow fields at a specified wavelength the influences of layer thickness and viscosity ratio on the flow fields are considered it is found that for a given wavelength layer thickness has a far stronger influence on flow fields than does viscosity ratio for all configurations inspected the dependence of growth rate on wavenumber exhibited one maximum meaning that a variable viscosity model does not produce multiple wavelengths maximum growth rates occur at wavelengths corresponding to the layer thicknesses we infer that loading instabilities occurring at wavelengths around the layer thicknesses are consistent with the effective pressure dependent viscous model

constraints on the preservation of diamict facies melt out tills at the margins of stagnant glaciers abstract this paper reviews the formation and preservation of diamict facies melt out till generated in situ by the downwasting of stagnant ice at the margins of continental glaciers melt out tills are commonly envisaged as being the product of the top supraglacial or bottom subglacial melt of stagnant debris rich glacier ice but such deposits are relatively uncommon in modern glacier environments where they are thin laterally discontinuous and have a low preservation potential theoretical considerations of the distribution of englacial debris in continental ice sheets show that only the glacier margin is likely to contain the necessary volumes of englacial debris for melt out to be a significant diamict forming process however the application of thaw consolidation theory to the formation of such deposits shows that substantial porewater pressures and self sediment deformations can be induced during melt out especially in matrix rich debris the classic melt out mechanism widely invoked in the literature since 1875 and involving passive in situ aggregation from thawing englacial debris can be seen to operate under restricted conditions diamict facies produced by melt out are likely to form spatially disjunct and laterally discontinuous elements within complex and ice marginal stratigraphics the melt out process is not a mechanism whereby regionally extensive diamiet ite units can be deposited across glaciated basins

deforming beds viscous and plastic scales of deformation small scale field and laboratory observations of sub glacial sediment deformation suggest that failure is the predominant method of sediment deformation while large scale modelling studies using a viscous model of till deformation have been reasonably successful in predicting the geological consequences of ice sheet action this suggests that the cross over scale between viscous and plastic deformation occurs at a much larger scale than the grain grain interaction scale previously thought to be appropriate to deforming till sediment deformation and the drainage of sub glacial areas are considered at different scales and how these interact to produce failure and viscous behaviour is discussed a fluctuation length scale is proposed whose horizontal dimensions are of the order of the depth of the base of deformation 1 10 m on this length scale the glacier deforming bed system is highly variable in time as well as in space till deformation occurring at this length scale is plastic happening though failure events three other specific scales are proposed whose different properties depend on the relative spatial variability of static and seepage pressures and topography the key theoretical problem which has yet to be solved is how multiple small scale failure events combine into a viscous type flow this is discussed in the context of self organised criticality it is argued that the length scales appropriate for some drainage features are not appreciably larger than the scale for plastic failure events implying that modelling sub glacial drainage channels by balancing erosion rates against viscous closure of the channel is misconceived the outlines of an alternative model involving percolation theory are presented certain key questions which can only be settled through observations by glaciologists and glacial geologists are discussed it is suggested that the difference between lodgement tills and deformation tills reflects the rate of motion of till by deformation and that lodgement from the ice is unimportant

late quaternary diatom assemblages from prydz bay eastern antarctica abstract the paleo depositional environment of inner prydz bay east antarctica has been reconstructed for the past 21 320 14c yr b p using diatom assemblages and sediment facies from a short 352 cm long gravity core between 21 320 and 11 650 14c yr b p compact tillite and diamicton are present in the core and diatom frustules are rare to absent these data suggest that an ice sheet grounded over the site during the last glacial maximum following glacial retreat siliceous muddy ooze was deposited from 11 650 to 2600 14c yr b p in an open marine setting during this stage diatom frustules are abundant and well preserved and thalassiosira antarctica resting spores and fragilariopsis curta dominate the assemblage this assemblage suggests open marine deposition in an environment where the spatial and temporal distribution of sea ice is less than today since 2600 14c yr b p sea ice and ice edge diatom species have become more abundant and neoglacial cooling is inferred the assemblage is similar to that forming currently in prydz bay where sea ice is absent

proglacial deposition and deformation in the upper carboniferous to lower permian wynyard formation tasmania a process analysis abstract the wynyard formation of tasmania australia provides the youngest evidence of grounded ice during the late carboniferous early permian in the tasmania basin of southeastern gondwana during the late paleozoic ice age within the wynyard formation four facies associations are recognized 1 massive diamictite 2 stratified diamictite 3 conglomerate and sandstone and 4 deformed mudstone and fine sandstone a detailed facies analysis was performed in order to interpret the depositional processes and environments the massive diamictite facies association contains massive diamictite and sandstone and was deposited primarily by iceberg rain out in a subaqueous morainal bank setting the stratified diamictite facies association is composed of stratified diamictite sandstone and conglomerate and was deposited by debris flows and iceberg rain out and deformed by glacial pushing the conglomerate and sandstone facies association is made up of cross stratified channelized conglomerate and pebbly sandstone that were deposited by glacial outwash on grounding line fans the deformed mudstone and fine sandstone facies association is composed of pervasively deformed pebbly mudstone and fine grained sandstone that exhibit volcano flame and dyke structures this facies association was deposited by a combination of suspension settling iceberg rain out and soft sediment deformation in a quiet distal proglacial setting the facies analysis supports the interpretation that the wynyard formation was deposited by a wet based tidewater glacier or glaciers the depositing glacier s occupied a 40 km wide trough in northwest tasmania based on the distribution of the wynyard formation and the presence of glacial deposits in other eroded troughs in tasmania glaciation occurred in the region within broadly eroded valleys the wynyard formation and overlying mudstone of the inglis formation provide a glacial postglacial signature similar to those in south africa antarctica and eastern australia during the latest carboniferous early permian therefore the climate warmed in southern gondwana following this glacial interval the continued glaciation in eastern australia was a result of regional topography and oceanographic processes

clastic dykes in over consolidated tills evidence for subglacial hydrofracturing at killiney bay eastern ireland abstract a swarm of vertical gravel filled dykes up to 6 m high and several decimetres wide cut through an over consolidated till at killiney bay the dykes are rooted in a gravel layer and many display plumes of clastic debris ejected into the overlying sediments burst out structures such features have not previously been described these clastic dykes are interpreted as the infillings of hydrofractures which formed when water pressures in the basal gravel layer exceeded the overburden pressure and tensile shear strength of the capping till the burst out structures extend up to 7 m from the tops of the dykes and provide strong evidence for forceful upward flow evidence suggests that the hydrofractures formed subglacially probably during a minor re advance their presence in late devensian 26 13 ka bp tills with an irish sea provenance irish sea till may have important implications for the subglacial hydrology of the last irish sea ice sheet these hydrofractures cannot form in unconsolidated glacimarine sediment and their presence precludes a glacimarine origin for these deposits they greatly affect the geotechnical properties of irish sea tills in particular providing very permeable routes through otherwise impermeable layers with important consequences in situations elsewhere in the irish sea basin where they have been used as aquicludes in landfill and low level nuclear waste disposal sites

expanding the utility of uranium series dating of speleothems for archaeological and palaeontological applications uranium series u series dating of speleothems is frequently used for palaeoclimate studies but its archaeological and palaeontological applications are limited to stratigraphically significant speleothem formations such as flowstones to provide maximum and minimum temporal points this study targeted soda straw stalactites for u series dating in contrast to other speleothem formations soda straw stalactites are fragile have typically short life spans usually only years but rarely up to a few hundred years and are frequently incorporated into cave deposits results of thermal ionisation mass spectrometry tims u series dating of soda straw stalactites from palaeontological excavations at blanche cave south australia show that small dense clean straws tend to yield ages closest to the time of stratigraphic deposition a correlation between soda straw u series ages and radiocarbon ages of charcoal from the site is shown multiple soda straw age determinations for a single stratigraphic unit are required in order to verify age concordance in conjunction with other dating methods u series dating of soda straw stalactites may help to significantly constrain the age of stratigraphic units and associated archaeological and palaeontological deposits in order to provide more robust chronologies here we advocate the collection of soda straw stalactites at future excavations of limestone cave sites

chronological overlap between humans and megafauna in sahul pleistocene australia new guinea a review of the evidence abstract over 60 faunal species disappeared from the australian continent during the middle late pleistocene most of these animals were large to gigantic marsupials birds and reptiles a terminal extinction date of 46 4 kyr has been proposed for the megafauna with all sites containing younger fossil megafauna dismissed by some researchers because of questions over stratigraphic integrity or chronologies the timing of the extinctions is argued to be broadly coincident with estimates of first colonization of the continent by modern humans and explanatory extinction models involving humans have subsequently gained currency however there is considerable evidence to suggest that in some parts of the continent people and some species of megafauna may have co existed well beyond 46 4 kyr in other places such as tasmania and the north of the continent there is no known record of a human megafauna temporal overlap a review of the available evidence indicates that only 13 species of megafauna were extant on human arrival in australia the archaeology of this period indicates that rather than a focus on big game hunting or firestick farming it was characterized by regional variability in subsistence strategies consistent with the range of environmental zones at the present time there is no substantive argument for a terminal extinction date of 46 4 kyr the current evidence indicating that there is no specific time period that correlates to any single mass extinction event on the basis of available evidence arguments for either human or climatic causation are entirely circumstantial and implicitly require acceptance of many unproven assumptions claims to have eliminated climate as a primary driver are premature and the recent focus on delivering proof of human causation in pleistocene faunal extinctions diverts attention from achieving a better understanding of the differential impacts of climate change and short term climatic flux in a land of environmental extremes

sediment deformation beneath glaciers rheology and geological consequences experiments beneath breidamerkurjokull in iceland have led to development of flow laws for the subglacial till relating strain rate to shear stress and effective pressure and assuming either bingham fluid or nonlinearly viscous fluid behavior water pressures in the till are less than ice pressures and it is suggested that this may lead to infiltration of ice into the sediment which inhibits sliding at the ice sediment interface where water pressures are equal or near to ice pressures infiltration does not occur and sliding may result a one dimensional theory of subglacial deformation is developed in which the empirical flow law is coupled with a model of subglacial hydrology and consolidation this predicts stable states in which subglacial sediment either does not deform or a dilatant deforming horizon forms with positive effective pressures at the ice bed interface or unstable states where zero or negative effective pressures are predicted time dependent analyses show that response times following perturbations of the system may be of the order of 103 years and thus that unsteady behavior may be normal on glaciers flowing over unlithified sediment beds it is suggested that the natural variability of material properties in subglacial sediment beds leads to the development of drumlins on the glacier bed it is suggested that unstable deformation at zero or negative effective stress leads to piping in subglacial sediments at the glacier terminus and the growth of sediment floored subglacial tunnels their frequency is that which is sufficient to draw down subglacial water pressures so as to prevent unstable deformation where they discharge large water volumes subglacial sediments flow laterally toward them producing tunnel valleys this sediment is then removed by water flowing along the axial tunnel tunnel valleys can be regarded as the equivalent in soft sediment areas of eskers in bedrock areas

magnetic enhancement and palaeoclimate study of a loess palaeosol couplet across the loess plateau of china summary the origin of the milankovitch palaeoclimatic signal so dramatically recorded in the chinese loess remains uncertain at least five hypotheses have been put forward to explain the well documented enhancement of magnetic susceptibility in palaeosols which formed when conditions were warmer and wetter we report here a magnetic study of a prominent loess soil couplet l4 s3 at three widely separated sites where present day mean annual rainfall and temperature range from 350mm to 700mm and from 6 c to 13 c the properties determined are laboratory remanences isothermal irm anhysteretic arm viscous vrm including viscous decay room temperature susceptibility and thermomagnetic behaviour at fields beyond 100 mt the irm spectra are all essentially identical both in shape and in absolute magnitude suggesting a uniform magnetic component widespread across the plateau subtracting the signal of this component isolates a second component the amount of which varies by an order of magnitude between sites the magnetic properties of this latter material are remarkably similar to those reported for bacterial magnetite in geological sediments and modern soils viscous decay of vrm takes place in two distinct stages one of which falls to zero in 10min we attribute magnetic enhancement which is the source of the palaeoclimatic signal to in situ pedogenetic formation of magnetite which we characterize in our interpretation as two separate forms of bacterial magnetofossils the most magnetic sample requires a mass fraction of about half of one per cent of this biogenic material

mass spectrometric 230th 234u 238u dating of the devils hole calcite vein the devils hole calcite vein contains a long term climatic record but requires accurate chronologic control for its interpretation mass spectrometric u series ages for samples from core dh 11 yielded 230 th ages with precisions ranging from less than 1 000 years 2 for samples younger than 140 ka thousands of years ago to less than 50 000 years for the oldest samples 566 ka the 234 u 238 u ages could be determined to a precision of 20 000 years for all ages calcite accumulated continuously from 566 ka until 60 ka at an average rate of 0 7 millimeter per 10 3 years the precise agreement between replicte analyses and the concordance of the 230 th 238 u 234 u 238 u ages for the oldest samples indicate that the dh 11 samples were closed systems and validate the dating technique in general

palaeoclimatic significance of magnetic properties from late quaternary lacustrine sediments at pithoragarh kumaun lesser himalaya india abstract mineral magnetic studies were carried out on lacustrine deposits from pithoragarh palaeolake kumaun lesser himalaya india these deposits have already provided valuable information for the reconstruction of palaeoclimatic changes and tectonic uplift in the himalayan region according to radiocarbon chronology the lake existed from 35 to 10 kyr bp using magnetic data radiocarbon ages and lithology the top of the well studied 13 m thick wadda section can be correlated to the basal part of the 4 7 m thick riyasi section fuzzy c means cluster analysis using only magnetic parameters enables a subdivision of the riyasi section into five magnetic zones based on three clusters these clusters are related to the relative contribution of the various magnetic constituents i e coarse hem c and ultrafine hem f grained hematite both showing relatively soft magnetic behaviour for the lowermost three zones existing pollen data from the wadda section helps to establish the climatic implications of the magnetic clusters and zones the model is as follows during humid periods magnetic mineralogy is mainly controlled by hem f formed in situ whereas during colder and more arid conditions detrital input of hem c and also hem f from the catchment area predominates climatic interpretation for the upper part of the section is attempted on the basis of the magnetic data but has to be confirmed by further pollen studies

holocene paleoclimate change in the antarctic peninsula evidence from the diatom sedimentary and geochemical record abstract holocene marine deposition in lallemand fjord antarctic peninsula is reinterpreted using statistical analyses cluster analysis analysis of variance nonmetric multidimensional scaling and multiple regression to compare diatom assemblages and the primary sedimentological proxies the assemblages have been deposited in a variable sea ice zone over the last ca 10 500 yr bp in response to a climate change in the late pleistocene early holocene 10 580 7890 yr bp a sea ice diatom assemblage was deposited in the presence of a retreating ice shelf at the head of the fjord in the mid holocene 7890 3850 yr bp an open water assemblage was deposited and sea ice cover was at a minimum we associate the assemblage with climatic warming which characterizes much of the antarctic peninsula during this time a second sea ice assemblage different from that deposited in the early holocene has been deposited in lallemand fjord since the late holocene

sliding of till over bedrock scratching polishing comminution and kinematic wave theory the observed ratio of removal of material by i scratches gouged by large clasts and ii polishing by debris suggests that the latter is the dominant form of bedrock erosion we examine this with a multi stage breakdown model of glacial debris which includes active erosion by fines these models suggest that a mother clast can through the action of its daughter debris erode several times its own volume of bedrock till sliding over bedrock is likely to be a potent source of scouring by proposing a till bedrock sliding law we investigate the kinematics of sliding till bodies ice flow naturally tends to thin and extend till cover even in the absence of longitudinal gradients in the applied stress thicker till cover has an increased effective pressure at its base a lower sliding velocity and for larger thicknesses a decrease in sediment flux with thickness this implies backward moving kinematic waves and shocks it is suggested that this is related to the blunt upstream faces of drumlins and that drumlinization can be a consequence of debris sliding over bedrock

dating of quaternary lake sediments from the schirmacher oasis east antarctica by infra red stimulated luminescence irsl detected at the wavelength of 560 nm abstract twelve samples from three antarctic lake cores in the schirmacher oasis east antarctica were selected for dating by a method using infra red stimulated luminescence irsl a spectral study of the luminescence signal from coarse grain plagioclase feldspars by a high sensitivity tl osl spectrometer using a ccd camera showed four wavelength maxima and the comparison of the equivalent doses d e measured at these wavelength namely 280 330 410 and 560 nm yielded different values the ages were calculated using d e obtained at 560 nm

new u th ages for pleistocene megafauna deposits of southeastern queensland australia arguments over the extinction of pleistocene megafauna have become particularly polarised in recent years causes for the extinctions are widely debated with climate change human hunting and or habitat modification or a combination of those factors being the dominant hypotheses however a lack of a spatially constrained chronology for many megafauna renders most hypotheses difficult to test here we present several new u th dates for a series of previously undated megafauna bearing localities from southeastern queensland australia the sites were previously used to argue for or against various megafauna extinction hypotheses and are the type localities for two now extinct pleistocene marsupials including the giant koala phascolarctos stirtoni the new dating allows the deposits to be placed in a spatially and temporally constrained context relevant to the understanding of australian megafaunal extinctions the results indicate that the joint texas caves megafaunal assemblage is middle pleistocene or older 292 ky the cement mills gore megafaunal assemblage is late pleistocene or older 53 ky and the russenden cave bone chamber texas caves megafaunal assemblage is late pleistocene 55 ky importantly the new results broadly show that the sites date prior to the hypothesised megafaunal extinction window i e 30 50 ky and therefore cannot be used to argue exclusively for or against human climate change extinction models without first exploring their palaeoecological significance on wider temporal and spatial scales

extinction chronology of the cave lion panthera spelaea abstract the cave lion panthera spelaea was widespread across northern eurasia and alaska yukon during the late pleistocene both morphology and dna indicate an animal distinct from modern lions probably at the species level so that its disappearance in the late pleistocene should be treated as a true extinction new ams radiocarbon dates directly on cave lion from across its range together with published dates from other studies totalling 111 dates indicate extinction across eurasia in the interval ca 14 14 5 cal ka bp and in alaska yukon about a thousand years later it is likely that its extinction occurred directly or indirectly in response to the climatic warming that occurred ca 14 7 cal ka bp at the onset of greenland interstadial 1 accompanied by a spread of shrubs and trees and reduction in open habitats possibly there was also a concomitant reduction in abundance of available prey although most of its probable prey species survived substantially later at present it is unclear whether human expansion in the lateglacial might have played a role in cave lion extinction gaps in the temporal pattern of dates suggest earlier temporary contractions of range ca 40 35 cal ka bp in siberia during mis 3 and ca 25 20 cal ka bp in europe during the last glacial maximum but further dates are required to corroborate these the holocene expansion of modern lion panthera leo into south west asia and south east europe re occupied part of the former range of p spelaea but the late pleistocene temporal and geographical relationships of the two species are unknown

soft sediment deformations from glaciodeltaic glaciolacustrine and fluviolacustrine sediments in the kleszczow graben central poland

ductile and brittle styles of subglacial sediment deformation an example from western ireland abstract in western ireland within a drumlin formed inside the margin of the late pleistocene ice sheet a range of different styles of ductile and brittle sediment deformation is observed within subglacial diamicton till and associated subglacial waterlain sediments at roonah point county mayo the structures associated with these different deformation styles include gravel clusters that have loaded subjacent sediments glacitectonic shears water escape structures and clastic dikes these structures are found for tens of metres laterally within the same diamicton units and the structures may cross cut or be superimposed upon one another based on these properties and geometric relationships the relative chronology and processes and patterns of subglacial deformation can be reconstructed including an evaluation of subglacial conditions and pore water pressure regimes this illustrates the relationship between glacitectonic forcing by ice bed coupling and the structural response within subglacial sediments to changing pore water pressure gradients

glacial lakes and geomorphological evolution of schirmacher oasis east antarctica during late quaternary large former glacial lakes and their sediments are described from the schirmacher oasis region of east antarctica the water bodies were present during the late quaternary 10 3 ka bp and have reduced in size by negative water balance this desiccation can possibly be attributed to the combined effect of recession of glaciers feeding them low melt water low precipitation and strong winds seven representative sections from five dry lake beds have been studied using loss on ignition loi and magnetic susceptibility ms the loi indicates a very low organic content while ms enables assumptions to be made about the reconstruction of changing detrital input detailed study of sediment profiles was used to reconstruct the evolution of the schirmacher oasis from 13 ka bp to the present these lacustrine sediments are a very important source of information on the quaternary geological history of the schirmacher oasis

viscosity ratio estimates from natural rayleigh taylor instabilities the geometry of natural gravity driven overturns potentially contains information on viscosity ratios of the material involved irregularities at the interface between two superposed horizontal fluid layers tend to amplify and grow with time with a regular wavelength if the top iayer is more dense published formulas woidt for such rayleigh taylor r t instabilities have been used to construct graphs which can constrain the effective viscosity ratio at the onset of the overturn only the initial thicknesses of the two layers and the final wavelength of the structures need be known the theory is based on an infinite two layer system of newtonian fluids between rigid boundaries with no slip or free slip at contacts geological examples included are soft sediment dewatering on the scale of decimetres in northern norway an unusual instability between basalt and sand in australia of hundreds of metres salt diapirism of kilometres in germany and the persian gulf and granitic diapirism from northern sweden of tens of kilometres viscosity ratios in the order of 1 10 are found for soft sediments with the top layer as the more viscous ratios inferred from patterns of salt diapirs are very large with the overburden approximately 103 105 times more viscous than the salt the viscosities of granites are indicated as lower than their overburden and with ratios of 103

the origins of glacially related soft sediment deformation structures in upper ordovician glaciogenic rocks implication for ice sheet dynamics in the upper ordovician glaciogenic rocks of west gondwana many soft sediment deformation structures are attributed to glaciotectonic processes however little is known about the subglacial and ice marginal processes associated with this ice sheet a systematic description and interpretation of these soft sediment deformation structures is supplemented by a comparison with late quaternary and modern glacial settings to provide qualitative constraints on the character of ancient subglacial thermal regimes soft sediment striations were formed by discontinuous shear induced deformation beneath an ice sheet that oscillated between warm and cold based thermal regimes beneath warm based ice coupling across the ice bed interface was poor with sliding and loading occurring at this surface loading of soft waterlogged sediments allowed the development of fluted surfaces which are also associated with the formation of truncated folded zones during times of cold thermal regimes coupling across the ice bed interface was enhanced by freezing which caused changes in the position of the freezing front these discontinuous changes coupled with sustained subglacial shearing resulted in the development of stacked soft sediment striated surfaces in areas where the subglacial substrate had an irregular topography complex shear zones formed that comprised stacked duplex systems interlayered with highly strained units preserving pervasive folded lineations at the ice front large glaciotectonic deformation structures comparable with push moraines developed during sustained periods of re advance that created composite thrust and fold systems deformation was transmitted for up to 1 km from the ice front and reduced in intensity with distance other deformation structures include dome like folds that consist of central anticlines 30 to 70 m in width with tight rim synclines that formed by the load induced diapiric intrusion of muds an ice sheet surging mechanism is inferred for the development of composite thrust and fold systems and the coeval sediment diapirs these surges potentially caused the widespread reorganisation of a glacial load resulting in the pro to subglacial extrusion of soft sediments

palaeoclimatic significance of late quaternary diatom assemblages from southern windmill islands east antarctica abstract the late quaternary palaeoenvironmental history of the southern windmill islands east antarctica has been reconstructed using diatom assemblages from two long well dated sediment cores taken in two marine bays the diatom assemblage of the lowest sediment layers suggests a warm climate with mostly open water conditions during the late pleistocene during the following glacial the windmill islands were covered by grounded ice preventing any in situ bioproductivity following deglaciation a sapropel with a well preserved diatom assemblage was deposited from 10 500 cal yr bp between 10 500 and 4000 cal yr bp total organic carbon corg and total diatom valve concentrations as well as the diatom species composition suggest relatively cool summer temperatures hydrological conditions in coastal bays were characterised by combined winter sea ice and open water conditions this extensive period of glacial retreat was followed by the holocene optimum 4000 to 1000 cal yr bp which occurred later in the southern windmill islands than in most other antarctic coastal regions diatom assemblages in this period suggest ice free conditions and meltwater stratified waters in the marine bays during summer which is also reflected in high proportions of freshwater diatoms in the sediments the diatom assemblage in the upper sediments of both cores indicates neoglacial cooling from 1000 cal yr bp which again led to seasonally persistent sea ice on the bays the holocene optimum and cooling trends in the windmill islands did not occur contemporaneously with other antarctic coastal regions showing that the here presented record reflects partly local environmental conditions rather than global climatic trends

water pressure coupling of sliding and bed deformation ii velocity depth profilesr b alley 130 139water pressure coupling of sliding and bed deformation iii application to ice stream b antarctica

mid holocene sea level and coral reef demise u th dating of subfossil corals in moreton bay australia it is increasingly apparent that sea level data e g microfossil transfer functions dated coral microatolls and direct observations from satellite and tidal gauges vary temporally and spatially at regional to local scales thus limiting our ability to model future sea level rise for many regions understanding sealevel response at far field locations at regional scales is fundamental for formulating more relevant sea level rise susceptibility models within these regions under future global change projections fossil corals and reefs in particular are valuable tools for reconstructing past sea levels and possible environmental phase shifts beyond the temporal constraints of instrumental records this study used abundant surface geochronological data based on in situ subfossil corals and precise elevation surveys to determine previous sea level in moreton bay eastern australia a far field site a total of 64 u th dates show that relative sea level was at least 1 1 m above modern lowest astronomical tide lat from at least 6600 cal yr bp furthermore a rapid synchronous demise in coral reef growth occurred in moreton bay 5800 cal yr bp coinciding with reported reef hiatus periods in other areas around the indo pacific region evaluating past reef growth patterns and phases allows for a better interpretation of anthropogenic forcing versus natural environmental climatic cycles that effect reef formation and demise at all scales and may allow better prediction of reef response to future global change

glaciation and deglaciation of the libyan desert the late ordovician record detailed outcrop studies at the flanks of al kufrah basin libya reveal the nature of glacially related sedimentation and post depositional deformation styles produced in association with the late ordovician glaciation during which ice sheets expanded northward over north africa to deposit the mamuniyat formation at the se basin flank jabal azbah the mamuniyat formation is sand dominated and incises interfingering braidplain and shallow marine deposits of the hawaz formation the glacially related sediments include intercalations of mud chip bearing tabular sandstones and intraformational conglomerates which are interpreted as turbidite and debrite facies respectively these record aggradation of an extensive sediment wedge in front of a stable former ice margin an increase in mudstone content northward is accompanied by the occurrence of more evolved turbidites a widespread surface bearing streamlined nw se striking ridges and grooves punctuates this succession the structures on the surface are interpreted to have formed during a regional north westward ice advance above siltstones bearing arthrophycus burrows and orthocone bearing sandstones beneath tidal bars testify to glaciomarine conditions for deposition of the underflow deposits beneath by contrast the northern basin margin jabal az zalmah is appreciably different in recording shallower water paralic sedimentation styles and major glaciotectonic deformation features although facies analysis also reveals northward deepening here a siltstone wedging from 8 to 50 m toward the north was deposited lower delta plain succeeded by climbing ripple cross laminated sandstones up to 60 m in thickness distal through proximal delta mouth bar deposits with occasional diamictite interbeds these rocks are deformed by thrusts and 50 m amplitude fault propagation folds the deformation locally sealed by a diamictite then overlain by conglomeratic lag during ultimate deglaciation integrating observations from both basin margins a model of fluvial dominated delta systems feeding a pulsed debrite and turbidite fan system in a shallow proglacial shelf is proposed

recent massive coral mortality events in the south china sea was global warming and enso variability responsible the key to predicting the possible response s of coral reefs to hypothesized future global warming is the knowledge of their response s to previous extreme climatic events we obtained 80 high precision u th ages for 78 dead massive porites colonies from the nansha islands south china sea with an aim to understand the longterm history frequency timing and causes of local coral mortality our results reveal a number of significant episodes of coral mortality since 1860 ad with an apparent increase in frequency and severity since 1930 ad and more recently since 1970 especially when only synchronized mortality events found to have occurred on both reefs were compared the synchronized mortality events centered around 1865 1875 1895 1900 1910 1920 1930 1945 1970 1985 and 1990 2005 ad which imply regional common causes were found to correlate well with the warm phases of the el ni n over tildeo southern oscillation enso i e el ni n over tildeo years e g some recent ones during 1972 1973 1982 1983 1991 1994 1997 1998 ad on inter annual time scale as well as with positive phases of the pacific decadal oscillation pdo or its sharp phase transitions on inter decadal time scale synchronized coral mortality was absent during prolonged negative pdo phases e g during 1950 1970 ad overall the data shows that immediately before and at the time of modem local ecological monitoring the region s coral communities had already experienced several recent episodes of stress the increased frequency distribution of mortality ages since 1930 ad and more recently since 1970 ad appears to coincide with progressively warmer sea surface temperatures both regionally and globally our data highlight the vulnerability of local coral communities in the face of present and predicted future warming c 2012 elsevier b v all rights reserved

discerning the timing and cause of historical mortality events in modern porites from the great barrier reef the life history strategies of massive porites corals make them a valuable resource not only as key providers of reef structure but also as recorders of past environmental change yet recent documented evidence of an unprecedented increase in the frequency of mortality in porites warrants investigation into the history of mortality and associated drivers to achieve this both an accurate chronology and an understanding of the life history strategies of porites are necessary sixty two individual uranium thorium u th dates from 50 dead massive porites colonies from the central inshore region of the great barrier reef gbr revealed the timing of mortality to have occurred predominantly over two main periods from 1989 2 4 1 to 2001 4 4 1 and from 2006 4 1 8 to 2008 4 2 2 a d with a small number of colonies dating earlier overall the peak ages of mortality are significantly correlated with maximum sea surface temperature anomalies despite potential sampling bias the frequency of mortality increased dramatically post 1980 these observations are similar to the results reported for the southern south china sea high resolution measurements of sr ca and mg ca obtained from a well preserved sample that died in 1994 6 2 3 revealed that the time of death occurred at the peak of sea surface temperatures sst during the austral summer in contrast sr ca and mg ca analysis in two colonies dated to 2006 9 3 0 and 2008 3 2 0 suggest that both died after the austral winter an increase in sr ca ratios and the presence of low mg calcite cements as determined by sem and elemental ratio analysis in one of the colonies was attributed to stressful conditions that may have persisted for some time prior to mortality for both colonies however the timing of mortality coincides with the 4th and 6th largest flood events reported for the burdekin river in the past 60 years implying that factors associated with terrestrial runoff may have been responsible for mortality our results show that a combination of u th and elemental ratio geochemistry can potentially be used to precisely and accurately determine the timing and season of mortality in modern massive porites corals for reefs where long term monitoring data are absent the ability to reconstruct historical events in coral communities may prove useful to reef managers by providing some baseline knowledge on disturbance history and associated drivers 2014 elsevier ltd all rights reserved

preliminary u series and thermoluminescence dating of excavated deposits in liang bua sub chamber flores indonesia we report the results of a test excavation of deposits in a limestone cave sub chamber located beneath the main chamber of liang bua flores indonesia the discovery site of the small hominin species homo floresiensis well preserved remains of extinct pleistocene fauna and stone artefacts have previously been identified on the surface of a sediment cone within the sub chamber our excavation of the deposits at the base of the sediment cone in the sub chamber to 130 cm depth yielded only a few fragmentary bones of extant fauna uranium thorium u series or u th dating of soda straw stalactites excavated from 20 to 130 cm in depth demonstrates that the excavated sediments were deposited during the holocene red thermoluminescence tl dating of the sediments at the base of the excavation 130 cm depth indicates these sediments were last exposed to sunlight at 84 15 ka thousand years similar to red tl ages of cave sediments from the main chamber together these results indicate that the surface faunal remains which are morphologically analogous to pleistocene finds from the main chamber excavations were transported to the sub chamber relatively recently from the main chamber of liang bua and probably originated from conglomerate deposits at the rear of the cave and from deposits around the front entrance there is no evidence for hominin occupation of the sub chamber instead it seems to have acted as a sink for cultural materials and fossil remains transported from the surface via sinkholes despite the small number of finds from the test excavation it is possible that more extensive excavations may yield additional transported cultural and faunal evidence at greater depths c 2012 elsevier ltd all rights reserved

the stability of a viscous till sheet coupled with ice flow considered at wavelengths less than the ice thickness a turbation method is used to analyse the stability of a thin till layer overlain by a deep ice layer ice is modelled as a linearly viscous fluid while the till viscosity has power law dependence on stress and effective pressure a linearized set of equations yields descriptions of the coupling of the ice flow with the sediment flow and reveals parameter ranges where the till perturbation amplitude can grow this shect flow instability is an essential part of any theory of drumlin formation and shows that viscous models of till have the ability to explain typical deforming bed features this is of great significance for large scale ice shect modelling

aseismic controls on in situ soft sediment deformation processes and products in submarine slope deposits of the karoo basin south africa intervals of soft sediment deformation features including vertical fluid escape and load structures are common and well exposed in permian lower slope deposits of the tanqua depocentre karoo basin the structures mainly comprise elongated flames and load structures associated with ruptured sandstones and structureless siltstones observed over a range of scales the presence of an upper structureless siltstone layer linked to the flames interpreted as a product of the debouching of fine grained material transported through the flame onto the palaeo seabed together with the drag and upward folding of lower sandstone layers is evidence that the flames were formed in situ by upward movement of sediment rich fluids flames are oriented parallel to the deep water palaeoslope in lateral splay deposits between two major slope channel complexes statistical correlation and regression analyses of 180 flame structures from seven stratigraphic intervals suggest a common mechanism for the deformation and indicate the importance of fluidization as a deformation mechanism importantly deformation occurred in an instantaneous and synchronous manner liquefaction and fluidization were triggered by incremental movement of sediment over steeper local gradients that were generated by deposition of a lateral splay on an inherited local north west facing slope seismic activity is not invoked as a trigger mechanism because of the restricted spatial occurrence of these features and the lack of indications of earthquakes during the time of deposition of the deep water succession the driving mechanisms that resulted in the final configuration of the soft sediment deformation structures involved a combination of vertical shear stress caused by fluidization development of an inverse density gradient and a downslope component of force associated with the local slope ground penetrating radar profiles confirm the overall north east orientation of the flame structures and provide a basis for recognition of potential larger scale examples of flames in seismic reflection data sets

environmental magnetism past present and future environmental magnetism involves the application of rock and mineral magnetic techniques to situations in which the transport deposition or transformation of magnetic grains is influenced by environmental processes in the atmosphere hydrosphere and lithosphere the first explicit description of environmental magnetism as a distinct field was in 1980 since that time environmental magnetism has become a broad field that is finding application in an ever increasing array of scientific disciplines in this review of the present state of environmental magnetic studies we divide the field into three broad but arbitrary categories the first involves the use of mineral magnetic assemblages in the geological record to study physical processes in depositional environments this category includes the correlation of sediment cores using magnetic susceptibility measurements studies of geomagnetic field behavior the analysis of depositional and postdepositional mechanical processes that affect sediments and the examination of magnetic parameters that might represent proxies for paleoclimatic variation the second category encompasses studies of the processes responsible for variations in the magnetic minerals brought into a sedimentary environment these provenance investigations include studies of changes in catchment derived sediment in lakes fluctuations in contributions from terrigenous aeolian and glaciogenic components in deep sea sediments and the origin of atmospheric particulates the final category addresses in situ changes and transformations of magnetic minerals in sedimentary environments including pedogenesis authigenetic diagenetic formation of ferrimagnetic phases dissolution of magnetic minerals due to reductive diagenesis and contributions of biomagnetism to sedimentary magnetism because environmental magnetism can address problems in so many disciplines and because many of these problems may be inaccessible to other techniques it is likely that the scope of environmental magnetism will continue to expand rapidly environmental magnetism is capable of providing important data for studies of global environmental change climatic processes and the impact of humans on the environment all of which are major research initiatives in the international scientific community these factors suggest that environmental magnetism has a bright and diverse future

geological constraints on glacio isostatic adjustment models of relative sea level change during deglaciation of prince gustav channel antarctic peninsula the recent disintegration of antarctic peninsula ice shelves and the associated accelerated discharge and retreat of continental glaciers has highlighted the necessity of quantifying the current rate of antarctic ice mass loss and the regional contributions to future sea level rise observations of present day ice mass change need to be corrected for ongoing glacial isostatic adjustment a process which must be constrained by geological data however there are relatively little geological data on the geometry volume and melt history of the antarctic peninsula ice sheet apis after termination 1 and during the holocene so the glacial isostatic correction remains poorly constrained to address this we provide field constraints on the timing and rate of apis deglaciation and changes in relative sea level rsl for the north eastern antarctic peninsula based on geomorphological evidence of former marine limits and radiocarbon dated marine freshwater transitions from a series of isolation basins at different altitudes on beak island relative sea level fell from a maximum of c 15 m above present at c 8000 cal yr bp at a rate of 3 91 mm yr 1 declining to c 2 11 mm yr 1 between c 6900 2900 cal yr bp 1 63 mm yr 1 between c 2900 1800 cal yr bp and finally to 0 29 mm yr 1 during the last c 1800 years the new beak island rsl curve improves the spatial coverage of rsl data in the antarctic it is in broad agreement with some glacio isostatic adjustment models applied to this location and with work undertaken elsewhere on the antarctic peninsula these geological and rsl constraints from beak island imply significant thinning of the north eastern apis by the early holocene further they provide key data for the glacial isostatic correction required by satellite derived gravity measurements of contemporary ice mass loss which can be used to better assess the future contribution of the apis to rising sea levels

esr and u series analyses of faunal material from cuddie springs nsw australia implications for the timing of the extinction of the australian megafauna abstract the timing and cause of late pleistocene faunal extinctions in australia are subjects of a debate that has become polarised by two vigorously defended views one contends that the late pleistocene extinction was a short event caused by humans colonising the australian continent whereas the other promotes a gradual demise of the fauna over a period of at least 10 20 ka due to a combination of climatic changes and ecological pressures by humans cuddie springs is central to this debate as it is the only site known in continental australia where archaeological and megafauna remains co occur we have analysed more than 60 bones and teeth from the site by laser ablation icp ms to determine u and th concentrations and distributions and those with sufficiently high u concentrations were analysed for u series isotopes twenty nine teeth were analysed by esr these new results as well as previously published geochronological data contradict the hypothesis that the clastic sediments of stratigraphic unit 6 su6 are in primary context with the faunal archaeological and other materials found in su6 and that all have ages consistent with the optically stimulated luminescence osl estimates of 30 36 ka these young osl results were used to argue for a relatively recent age of the extinct fauna our results imply that su6 is either significantly older than the osl results or that a large fraction of the faunal material and the charcoal found in su6 was derived from older lateral deposits our u and th laser ablation icpms results as well as the ree profiles reported by trueman et al 2008 comparing rates of recystallisation and the potential for preservation of biomolecules from the distribution of trace elements in fossil bones c r palevol general paleontology taphonomy and fossilization 7 145 158 contradict the interpretation of previously reported rare earth element compositions of bones and the argument based thereon for the primary context of faunal material and clastic sediments in su6 layers

drumlinization and drumlin forming instabilities viscous till mechanisms glacially induced flow naturally tends to thin and extended till cover through shock formation even in the absence of longitudinal gradients in the applied stress thicker till cover has an increased effective pressure at its surface and base a lower sliding velocity or deformation rate and above a critical thickness a decrease in wave velocity with thickness leading to reverse facing shocks moving downstream for sliding and for some theologies of internal deformation a decrease in sediment flux with thickness occurs implying backward moving kinematic waves and reverse facing reverse moving shock downstream facing shocks are also formed which move upstream if the till is sliding and downstream if the till is deforming internally eventually shocks coalesce leaving an upstream lacing shock for sliding and a downstream facing shock for internal deformation it is observed that some drumlins have downstream blunt ends only fairly realistic three dimensional drumlin shapes can be produced from symmetric sediment bodies and barchan shapes can be produced from linear forms perpendicular to the ice sheet flow the fact that viscous theories produce drumlinoid forms suggests that on this scale till behaves viscously and the the lower length scale for drumlins represents the plastic viscous transition scale

speleothem derived asian summer monsoon variations in central china 54 46 ka the oxygen isotope signature delta o 18 of stalagmite si3 collected from shizi cave in north east sichuan province provides an asian summer monsoon asm record in central china for the period 54 46 ka the si3 delta o 18 record clearly shows a negative delta o 18 excursion centred around 49 4 ka which was reported in hulu cave in east china but not identified in the speleothem records from south west china as a whole this record displays a higher coherence with the two hulu records from east china than with the speleothem delta o 18 records from south west china suggesting that at 54 46 ka central china was influenced more by the east asian summer monsoon than by the indian summer monsoon it also displays a significant negative delta o 18 excursion at 47 5 46 6 ka which is not clearly documented in two other speleothem delta o 18 records previously reported from south west china this suggests that details of the greenland interstadial 12 warrant further investigations in future in monsoonal china the si3 delta o 18 record displays more significant centennial scale variations than the other four speleothem delta o 18 records from east and south west china which may be due to the fact that the study site is closer to the north west boundary of the asm and more sensitive to variations of the asm than east and south west china copyright c 2011 john wiley sons ltd

black box modeling of the subglacial water system measurements of water pressure beneath trapridge glacier yukon territory canada yield the following generalizations about subglacial conditions in the studied region 1 even over short distances the subglacial water system is highly heterogeneous 2 the subglacial water system consists of at least two distinct components which we refer to as the connected and unconnected water systems 3 regions of the glacier bed can switch back and forth from being part of the connected or part of the unconnected water system 4 large spatial pressure gradients can exist within the unconnected water system and between the connected and unconnected systems 5 rapid pressure variations can occur in the unconnected water system 6 pressure variations in the unconnected water system do not match those in the connected system and can in fact be strongly anticorrelated with pressure variations in the connected system if the water pressure variations in the connected system are viewed as a forcing and those in the unconnected system as a response to this forcing the input output relation between forcing and response can be efficiently represented as a low order nonlinear ordinary differential equation the response of the unconnected system to forcing from the connected system is governed by time constants having approximate magnitudes of 1 7 hours and 7 4 hours that we believe are associated with process rates for substrate compression and pore water diffusion respectively

a fluctuating ice front over an esker near ryssjon s sweden as a cause of a giant load cast abstract a well exposed section in an esker near ryssjon s sweden strongly affected by several phases of glacitectonism showed two phenomena that are uncommon and that seem to have a causal relationship the first phenomenon is the occurrence of a load cast consisting predominantly of gravel in deposits formed just inside or outside a tunnel mouth the load cast is over 3 m high and 8 m wide a size that has previously not been described from unconsolidated sediments two nearby somewhat smaller load casts consisting mainly of sand also have dimensions of over 2 m indicating that the formation of huge load casts was apparently a feature related to the special conditions under which loading could develop at this site the second remarkable feature is that not only is a till present in the succession above the load cast thus indicating re advance of the ice but deposits overlying this till are also deformed by glacitectonism proving that at least a second phase of ice re advance must have occurred this situation has not previously been documented it is concluded that the varying differential overburden of sediment and particularly the retreating and re advancing ice in this area were responsible for the formation of the extremely large load casts possibly triggered by seismic shocks related to isostatic adjustment caused by oscillations of the ice front

application of sedimentary and chronological analyses to refine the depositional context of a late pleistocene vertebrate deposit naracoorte south australia cave deposits of infill sediments and associated vertebrate fossils provide a valuable source of information on terrestrial palaeoenvironments climatic conditions and palaeocommunities in the deposits of the naracoorte caves world heritage area such records span the last 500 ka and are renowned for their rich diverse vertebrate assemblages previous research into the grant hall deposit of victoria fossil cave suggested that it may preserve the only peak last interglacial ca 125 ka faunal community within the world heritage area the current work tested this existing model for the age of faunal remains from grant hall using multiple techniques physical and geochemical properties of the visually homogeneous sediments were analysed at regular intervals through the sequence to establish meaningful stratigraphic divisions and sediment provenance optically stimulated luminescence dating of individual quartz grains indicates that sediments accumulated in grant hall from 93 8 to 70 5 ka minimum ages provided by u th dating of fossil teeth 72 3 2 2 to 38 2 0 8 ka are consistent with the luminescence chronology and show that the deposit represents a more recent faunal accumulation than previously modelled for the site u th ages on calcite straws within the deposit are significantly older than the sediments and fossil teeth 500 to 186 4 1 ka as such they provide no further constraint on the chronology of the deposit but do indicate that speleothem deposition was active over much of the middle pleistocene sedimentary analyses resulted in the identification of five depositional units contrasting with previous divisions which were based only on visual observation of the sedimentary sequence sediments within each unit are broadly classified as sandy silts with soil structures and may be indirectly derived from the lunettes of nearby bool lagoon although their ultimate provenance is unknown as a result of this work palaeoenvironmental reconstruction based on fossil remains in the deposit may be more accurately related to prevailing climatic and environmental conditions at the time of accumulation it also contributes to an understanding of the temporal occurrence of regional vertebrate faunas through the late pleistocene reinforcing the value of developing stratigraphically constrained chronologies for cave deposits based on multiple techniques

thermal ionization mass spectrometry u series dating of a hominid site near nanjing china mass spectrometric u series dating of speleothems from tangshan cave combined with ecological and paleoclimatic evidence indicates that nanjing man a typical homo erectus morphologically correlated with peking man at zhoukoudian should be at least 580 k y old or more likely lived during the glacial oxygen isotope stage 16 similar to 620 ka such an age estimate which is similar to 270 ka older than previous electron spin resonance and alpha counting u series dates has significant implications for the evolution of asian h erectus dentine and enamel samples from the coexisting fossil layer yield significantly younger apparent ages that of the enamel sample being only less than one fourth of the minimum age of nanjing man this suggests that u uptake history is far more complex than existing models can handle as a result great care must be taken in the interpretation of electron spin resonance and u series dates of fossil teeth

the human colonisation of australia optical dates of 53 000 and 60 000 years bracket human arrival at deaf adder gorge northern territory the date at which people entered australia has important implications for the debate on modern human origins thermoluminescence dates of 50 60 ka reported for initial occupation of the malakunanja ii site in northern australia have been used as a means of calibrating the rate of mitochondrial and nuclear dna evolution in modern humans optical dating of unburnt quartzose sediments from a rock shelter site nauwalabila i lindner site in deaf adder gorge 70 km south of malakunanja ii provides new evidence for the timing of the colonisation of the continent optical dates were determined for several stratigraphic levels within a 3 m deep excavation in which flaked stone artefacts and ground pigments were found in primary depositional setting the lowest human occupation levels are bracketed by dates of 53 4 5 4 ka and 60 3 6 7 ka while the upper levels show good agreement between optical and calibrated 14c age estimates high quality haematite with ground facets and striations is associated directly with the 53 ka level and indicates the use of pigments by these early australians the optical dates independently confirm evidence for the colonisation of northern australia shortly after 60 ka and should be seen in the context of this region as having been a likely entry route for the first human movements into sahul

responses of quaternary rainforest vertebrates to climate change in australia a new previous termmiddle pleistocenenext term vertebrate fossil record from eastern australia dated by u disequilibrium series records the first quaternary record of an australian tropical rainforest fauna this exceptionally rich fauna underwent extinction after a long period of relative faunal stability spanning several glacial cycles and persisted probably until 280 000 years ago some time between 280 000 and 205 000 years ago the rainforest fauna was replaced by a xeric adapted fauna since that time the xeric adapted fauna was replaced by a mesic adapted fauna which was established by the holocene this is the first vertebrate faunal evidence in australia of the previous termmiddle pleistocenenext term mid brunhes climatic event mbe a major climatic reorganisation that led to increased aridity in northern australia from around 300 000 years ago several independent palaeoclimate proxies suggest that the climatic shift to aridity was due to increased climatic variability and weakened northern monsoons which may be manifested in the extinction of the aseasonal rainforest fauna and its replacement by an arid adapted fauna we extend the temporal ranges of several taxa from the pliocene into the previous termmiddle pleistocene next term we also reveal a longer palaeobiogeographic connection of rainforest taxa and lineages shared between new guinea and australia than was previously thought and show that their extinction on mainland australia occurred sometime after 280 000 years ago

temporal overlap of humans and giant lizards varanidae squamata in pleistocene australia abstract an obvious but key prerequisite to testing hypotheses concerning the role of humans in the extinction of late quaternary megafauna is demonstrating that humans and the extinct taxa overlapped both temporally and spatially in many regions a paucity of reliably dated fossil occurrences of megafauna makes it challenging if not impossible to test many of the leading extinction hypotheses the giant monitor lizards of australia are a case in point despite commonly being argued to have suffered extinction at the hands of the first human colonisers who arrived by 50 ka it has never been reliably demonstrated that giant monitors and humans temporally overlapped in australia here we present the results of an integrated u th and 14c dating study of a late pleistocene fossil deposit that has yielded the youngest dated remains of giant monitor lizards in australia the site colosseum chamber is a cave deposit in the mt etna region central eastern australia sixteen new dates were generated and demonstrate that the bulk of the material in the deposit accumulated since ca 50 ka the new monitor fossil is minimally 30 ky younger than the previous youngest reliably dated record for giant lizards in australia and for the first time demonstrates that on a continental scale humans and giant lizards overlapped in time the new record brings the existing geochronological dataset for australian giant monitor lizards to seven dated occurrences with such sparse data we are hesitant to argue that our new date represents the time of their extinction from the continent rather we suspect that future fossil collecting will yield new samples both older and younger than 50 ka nevertheless we unequivocally demonstrate that humans and giant monitor lizards overlapped temporally in australia and thus humans can only now be considered potential drivers for their extinction

u series dating of soda straw stalactites from excavated deposits method development and application to blanche cave naracoorte south australia this study aimed to further test the method reported by st pierre et al 2009 to develop robust chronologies of deposits in limestone caves through u th uranium thorium or u series dating of soda straw stalactites the chronology of fossil bearing deposits at blanche cave was further constrained with thermal ionisation mass spectrometry tims u th dating of 17 additional soda straw stalactite samples and results were compared to recalibrated c 14 ages of charcoal the results support the assertion that soda straw stalactites can provide ages close to the time of sediment deposition and may be used as reliable chronological markers particularly for periods reaching or beyond the radiocarbon dating limit the application of an enhanced cleaning technique facilitated the reduction of detrital th in samples significantly increasing age accuracy and precision additionally u th age accuracy and precision was increased through the application of site specific measured u th ratios to correct for the detrital th 230 component in samples c 2011 elsevier ltd all rights reserved

an upper pliocene lacustrine environmental record from south western australia preliminary results abstract a crater created by a supposed meteor impact and located about 30 5 s latitude in western australia contains a well preserved lake sequence of the upper pliocene age this paper reports on the palaeomagnetic record sediment patterns and selected chemical analyses and alludes to some of the preliminary results from pollen charcoal and diatom analyses the chemical analyses indicate that the lake varied in water depth and that salinity and diatom production were related to climate change rather than changes in major nutrients the palynological analysis for the upper 20 m of sediment shows a woodland and heath similar to today interspersed with some chenopod shrub land phases and minor elements include nothofagus araucaria and phyllocladus which are known from other tertiary records from southern western australia charcoal is abundant in the record indicating that fire was a major environmental feature long before aboriginal people inhabited the continent the palaeomagnetic record shows a good match with the gaussian chron and includes the kaena and mammoth subchrons and these were used as a basis for developing an age depth model for the sequence the sediment was subdivided into an upper unit of four lithozones and a lower unit the upper unit that dates from ca 2 5 to 3 51 ma was interpreted to have formed under a generally wetter climate than today and with some relatively short intervals of semi arid climate identified around 2 56 and 2 59 ma they were interpreted from episodes of chenopod shrub land that were associated with assemblages of saline habitat diatoms and carbonate and gypsum in the sediments the sediment profile also included sections of laminated sediments which indicate that around 2 82 2 86 and 2 96 ma the climate was more variable and possibly seasonal compared to the rest of the record these data indicate that the last million years of the pliocene for south western australia endured several episodes of climate variability thus lending support to the idea that the pliocene was not a period of a uniform cooling trend gradually leading into the quaternary glacial episodes

flow mechanism of glaciers on soft beds subhourly measurements of bed deformation bed shear strength subglacial water pressure and surface speed at storglaciaren a glacier in northern sweden showed that the shear strain rates of the bed decrease during periods of high water pressure and surface speed high water pressures appear to be accompanied by a reduction in the coupling of ice with the bed that is sufficient to reduce or eliminate shearing the instability of large ice masses may result from similar decoupling rather than from pervasive bed deformation as has been commonly thought