terrestrial manganese 53 a new monitor of earth surface processes we report the first systematic study of the terrestrial cosmogenic radionuclide manganese 53 t1 2 3 7 ma measured in thirteen samples from nine dolerite surfaces in the dry valleys antarctica the terrestrial manganese 53 concentrations correlate well with cosmic ray produced helium 3 and neon 21 concentrations in the same samples implying that the manganese 53 is produced continuously in situ and retained quantitatively over millions of years the terrestrial manganese 53 production rate determination normalized to iron the only important target element and to high latitude and sealevel yields a value of p53 103 11 atoms yr 1 g fe 1 this is consistent with the theoretical value of 120 18 atoms yr 1 g fe 1 obtained from modeling calculations our results show that the manganese 53 concentrations in bulk terrestrial rocks can be used to monitor earth surface processes on time scales exceeding 10 my 2006 elsevier b v all rights reserved

voyages of seaweeds the role of macroalgae in sediment transport abstract at least 26 genera of macroalgae have been observed attached to and carrying sedimentary materials rock veneer or carbonate to beaches and the sea floor most studies have been descriptive with few quantifying flux rates this study reviews and quantifies the mainly biological literature on macroalgae mediated sediment transport in coastal and marine environments dislodgement of macroalgae from a hard substrate can result in erosion up to 0 01 mm y 1 the proportion of buoyant macroalgae carrying rock material usually a thin veneer but sometimes boulders up to 365 kg varies by location but can reach as high as 35 macroalgae carrying attached carbonate material e g crustose coralline algae shells are more common up to 85 of holdfasts on a beach may contain up to 116 g caco 3 each sand and carbonate trapped in haptera along with encrusting carbonate producing organisms have a mass of up to tens of grammes while most dislodged macroalgae land close to where they came from others may be stranded many thousands of km from their place of origin sediment deposited by macroalgal transport depends largely on the characteristics of local source rocks while hard rocks may only provide a few g m 2 y 1 highly fractured basalt has been shown to provide up to 78 g m 2 y 1 rock transport by macroalgae is less than carbonate flux which may reach over 8000 g m 2 y 1 based on the projected abundance of macroalgal rafts some 350 tonnes of sediment both carbonate and clastic may be afloat in the southern ocean at any one time macroalgal transport may explain the presence of exotic rocks and shells found far from their source environment while cold climate rafting of sediment is dominated by glacial processes in warm periods rafting may be limited to biological transport overall the transport of rock and carbonate by macroalgae has the potential in some environments of being a significant source of sediment

a major holocene enso anomaly during the medieval period 1 here we present a high resolution marine el nino flood record from peru a period of extreme drought without strong flooding occurred from a d 800 1250 anomalous precipitation patterns characterized the entire indo pacific enso domain with dry events in the northern arabian sea and the mid latitudes of both americas coinciding with wet periods in the atlantic cariaco basin the occurrence of contemporaneous moisture anomalies in other archives in the enso region highlights the role of el nino strength in global climate evolution during the late medieval period when temperature reconstructions show a rather heterogeneous pattern

beach ridges and prograded beach deposits as palaeoenvironment records abstract beach ridges are landforms commonly developed on prograded coasts with beach shorelines a sequence of beach ridges coupled with their subsurface deposits can be regarded as a time series of coastal evolution methodological advances in field surveying and chronology applicable to beach ridges have led to detailed palaeoenvironmental reconstructions to be derived from such sequences this paper reconsiders the basic aspects of beach ridges and deposits which need to be properly understood for their comprehensive interpretation in a palaeo environmental context it also reviews case studies in which beach ridge sequences have been used to unveil past sea level history catastrophic events and climate changes proposed formative processes of beach ridges include 1 progradation of sandy beach and berm formations in relation to fairweather waves coupled with aeolian foredune accumulation 2 building of gravel ridges by storm waves 3 welding of longshore bars beach ridge formation through sea level oscillation is thought to be questionable and caution is suggested for this process when undertaking palaeoenvironmental reconstruction beach deposit stratification is known to dip either landwards or seawards but landward dips are uncommon seaward dipping stratification is formed in relation to beachface progradation and is usually dissected in places by erosion surfaces resulting from episodic beach retreat the boundary between the foreshore and the underlying shoreface is well defined only in the case that longshore bars lead to complex bedding structure relative to that of the foreshore reliable chronology of beach ridges can be determined by radiocarbon and optically stimulated luminescence osl dating radiocarbon dating of articulated shells which are considered not to be extensively reworked provides robust results but osl dating is more useful as it enables direct dating of sediment grains it is noted that there are restrictions in chronological resolution and continuity inherent to beach ridge and beach deposits the plan view geomorphic expression of beach ridges typically consists of ridge sets with multi decadal intervals whereas their internal sedimentary structures define shorter time scales records of beach sedimentation and erosion are likely to be reworked by episodic high magnitude beach retreat and the resultant record of the net progradation is likely to be sporadic and discontinuous the height of sandy beach ridges is often variable due to differing degrees of aeolian sand accumulation and they are thus not used as sea level indicators unless purely wave built gravel ridge height is a relatively reliable indicator of sea level but can vary in response to storminess fluctuations subsurface sediment facies boundaries are preferred as sea level indicators and those proposed include boundaries of aeolian beach foreshore shoreface and upper lower shorefaces catastrophic events are expressed in both erosional and depositional records erosion surfaces or scarp imprints revealed in a cross section of beach deposits indicate storm or tsunami events however erosional events are likely to rework previous records of sedimentation and even other erosional events and thus the apparent history decoded from the resultant deposits tends to be biased several attempts for estimating the frequency and intensity of prehistoric cyclones rely on assumed relationships between the level of coarse sand beach ridges and cyclone inundation the formative process of coarse sand ridges remains uncertain and needs to be clarified as it constitutes the fundamental basis of these attempts the growth rates of beach ridge systems are expected to reflect fluctuations in river sediment discharge to the coast and in aeolian sand flux due to onshore winds both of which are affected by climate change assessment of the growth rate is potentially improved by ground penetrating radar survey of subsurface structure and by detailed chronology orientation of beach ridges reflects long term trends in wave direction inferred relationships between beach ridges and cyclic fluctuations of sea level and climate rely on weak assumptions and are not substantiated by rigid chronological evidence and thus remain highly questionable correlation between the inherently decadal signal of beach ridge intervals and possible climate cycles such as sunspot activity is probably coincidental as it lacks causal explanations

insight into the late holocene sea level changes in the nw atlantic from a paraglacial beach ridge plain south of newfoundland constructional sedimentary features can provide insight into past changes in relative sea level rsl in regions where traditional bio stratigraphic markers are absent the paraglacial beach ridge plain at miquelon langlade located 50 km south of newfoundland is an example of a well preserved regressive barrier initiation of this plain correlates with a decrease in the rate of rsl rise from 4 4 mm yr to 1 3 mm yr at around 3000 years ago it developed under conditions of normal regression during a period of slow rsl rise 1 3 mm yr the barrier is composed of two oppositely prograding mixed sand and gravel beach ridge systems which evolved contemporaneously along two open coasts the growth of these features reflects high rates of sediment influx that was sourced from the erosion of proximal glacigenic sediment moraines and reworked alongshore and across shore by wave action the combination of stratigraphic ground penetrating radar and sediment cores topographic rtk gps and chronologic optically stimulated luminescence osl data provide a detailed understanding of the constructional history of the plain the well defined contact between coarse grained wave built facies and overlying aeolian deposits is used to demonstrate the dominant influences of rsl change in the development of the barrier system and produce a rsl curve over the period of its formation a net increase of 2 4 m in the surface elevation of wave built facies is observed across the plain corresponding to the increase in mean sea level during its formation coupled with osl dates trends in elevation of the wave built facies across the plain are used to reconstruct the relative sea level history during this period acknowledging the uncertainties inherent in the method applied in this study three distinct periods of sea level rise can be distinguished 1 an increase from 2 4 to 1 m below modern msl between 2400 and 1500 years average rate of 1 3 mm yr 2 relatively stable or slowly rising rsl 0 2 mm yr from 1400 to 700 years and 3 a rise of ca 0 7 m during the past 700 years 1 1 mm yr this study not only produces the first rsl reconstruction for the saint pierre et miquelon archipelago but also provides i additional details of rsl changes in a region exhibiting great spatial variations in rsl histories newfoundland ii field confirmation that wave built aeolian stratigraphic contacts in beach ridges can provide a powerful tool for sea level reconstructions in mixed clastic systems and iii evidence that sediment influxes can outpace the rate of accommodation creation producing a broad progradational coastal system

geological and geophysical investigation of kamil crater egypt we detail the kamil crater egypt structure and refine the impact scenario based on the geological and geophysical data collected during our first expedition in february 2010 kamil crater is a model for terrestrial small scale hypervelocity impact craters it is an exceptionally well preserved simple crater with a diameter of 45 m depth of 10 m and rayed pattern of bright ejecta it occurs in a simple geological context flat rocky desert surface and target rocks comprising subhorizontally layered sandstones the high depth to diameter ratio of the transient crater its concave yet asymmetric bottom and the fact that kamil crater is not part of a crater field confirm that it formed by the impact of a single iron mass or a tight cluster of fragments that fragmented upon hypervelocity impact with the ground the circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the nw and an impact angle of approximately 30 to 45 newly identified asymmetries including the off center bottom of the transient crater floor downrange maximum overturning of target rocks along the impact direction and lower crater rim elevation downrange may be diagnostic of oblique impacts in well preserved craters geomagnetic data reveal no buried individual impactor masses 100 kg and suggest that the total mass of the buried shrapnel 100 g is approximately 1050 1700 kg based on this mass value plus that of shrapnel 10 g identified earlier on the surface during systematic search the new estimate of the minimum projectile mass is approximately 5 t

punctuated progradation of the seven mile beach holocene barrier system southeastern tasmania abstract prograded barriers are depositional coastal landforms which preserve past shoreline locations and have been studied in order to understand the fundamental drivers of barrier formation this paper reconstructs the holocene history of the seven mile beach prograded barrier in tasmania australia using optically stimulated luminescence osl dating ground penetrating radar gpr light detection and ranging lidar elevation models and sedimentological analyses shoreline progradation of the barrier commenced around 7300 years ago and continued to near present despite a 3000 pause in deposition between 6700 and 3600 years ago indicative of substantial changes in sediment availability gpr imaged subsurface structures contain a record of seaward dipping reflectors preserved as sediment supplied beaches and dunes leading to shoreline progradation in the past 500 years a large transgressive dune has formed built from reworked barrier sands and now dominates the eastern portion of the barrier implying that shoreline progradation has ceased this study reaffirms the notion that relict foredune ridges are strongly aligned with modal wave refraction patterns in planform and emphasises the importance of sediment delivery as a key driver of shoreline progradation through beachface and dune accretion the substantial pause in shoreline progradation on this barrier system as observed on others around the world requires further explanation although changes in sediment delivery have been inferred it may also be appropriate to reopen the debate on holocene sea level change in tasmania

simulation of large scale coastal change using a morphological behaviour model abstract quantitative simulation of large scale coastal behaviour lscb is possible using a model based only on principles of sand mass conservation and geometric rules for shoreface and active sand body morphology dynamic processes are subsumed into a set of parameters that define the geometry of the active cross shore profile which in turn can represent an entire coastal cell the parameters together with a set of local behaviour rules governing adjustments at discrete points along the profile provide a simple formulation that is constrained by sediment mass balance to yield emergent numerical solutions for profile kinematics the emergent qualities of this shoreface translation model are exemplified in simulation experiments on changes to sand deposits on the southeastern australian coast and shelf during the post glacial marine transgression in another example the model is used to simulate lscb over engineering time scales at an idiosyncratic site both examples illustrate the over riding importance of small residual sand movements that accumulate through time to cause lscb in comparison to gross sand movements the residuals are too small to measure directly or predict on the basis of available theory exploratory inverse simulation provides a quantitative method for side stepping these limitations the shoreface translation model therefore is used as a tool to explore possible forms of coastal behaviour through an approach that incorporates available data along with theoretical considerations validation is not strictly possible for this type of inverse approach so the degree to which a simulation reproduces observed features in nature is a measure of its success

26al and10be production in iron meteorites abstract we have measured by accelerator mass spectrometry the 26 al contents of 20 and the 10 be contents of 14 iron meteorites the 26 al contents are typically 30 or more lower than values obtained by counting techniques the 10 be contents are 10 15 lower the production rates p of these nuclides decrease by more than a factor of two as the 4 he 21 ne ratio increases with increasing shielding from 200 to 400 for the lighter shielding conditions expected in stony meteorites we estimate p 26 fe as 3 4 dpm kg and p 10 fe as 4 5 dpm kg the average p 10 p 26 activity ratio is close to 1 5 exposure ages calculated from 21 ne 26 al ratios cannot be calibrated so as to agree with both 40 kk ages and ages based on the shorter lived nuclides 39 ar and 36 cl if agreement with the latter is forced then the disagreement with 40 kk ages may signal a 35 increase in the cosmic ray intensity during the last 10 7 a

the southern oscillation index wave climate and beach rotation short embayed beaches bounded by headlands are a common feature along the southern and central coastline of new south wales australia many of these embayed beaches have experienced severe erosion at their southern end over the last decade previous studies have suggested that this erosion may be the result of an oscillatory medium term phenomenon known as beach rotation the present study was undertaken with the objectives of 1 establishing definitive links between the southern oscillation index soi wave climate and beach rotation and 2 determining the physical processes governing beach rotation data from two similar new south wales beaches were analysed using time series analysis techniques and image processing techniques using argus video images in this study the results indicate that the northern end of this type of beach accretes during el nino phases while the southern end erodes resulting in a net clockwise rotation of the beach the opposite occurs during la nina phases resulting in a net anti clockwise rotation of the beach the beach response at the northern and southern ends lags soi trend shifts by 3 and 17 months respectively waves are predominantly incident from the southeast during both el nino and la nina phases offshore wave height is positively correlated with the soi while offshore wave direction is negatively correlated with the soi on average the number of storms per year doubles from el nino to la nina based on these links between beach width fluctuations soi and incident wave conditions a conceptual model of beach rotation is presented the model describes the combinations of cross shore and longshore sediment transport and hydrodynamic processes that are expected to result in the observed clockwise and anti clockwise beach rotation during el nino and la nina phases respectively

coastal barriers fresh look at origins nomenclature and classification issues abstract based on numerous publications and field work on the northern gulf of mexico coast u s and other coastal areas the present objective is to meet the need for an improved system of the definition and classification of barriers and their components this topic includes morphological and functional interrelationships between beach ridges barriers and similar landforms the term beach ridge was applied to a plethora of sub and supratidal ridge types in contrast the presently proposed definition restricts the term to relict berm and foredune ridges composed of sand or gravel and stabilized after isolation from shore zone of active processes barriers sustain paralic hydrology sediment biotic and nutrient condition in the coastal realm in combination with adjacent lagoons and river deltas these landforms represent physical barriers that lessen marine and related influences in brackish paralic coastal environments benefiting from historic evolution of concepts and nomenclature the task also involves the correction of misattributions rooted in early publications island spit and mainland barriers thus maintain lower salinities reduce wave erosion protect nutrient rich paralic deposits and mitigate storm induced inundation fetch limited lagoonal barrier islands are considered valid barriers only in lagoons where they face inlet transmitted full marine conditions mainland barriers of several subcategories often are important sediment archives of past sea levels hydroclimate climate and tectonic isostatic changes they consist mostly of ridgeplains at the start firmly attached or later migrated and welded to the mainland shore in addition to local hydrodynamic and topographic influences formation conditions may reflect overall paleogeographic conditions including fluvial impact in progradational regressive island settings barriers consist mainly of strandplains that laterally may alternate with narrow spit like sectors they include only single marine respectively lagoon side shore ridges with secondary dune fields sandwiched between them field observations and drillcore studies of microfossil and sediment based depositional facies suggest that most barrier islands originated by the often underestimated shoal aggradation mode two additional genetic models are recognizable a fourth remains hypothetical remotely sensed images indicate that post hurricane regeneration of the largest deltaic barrier chain in the gulf of mexico stalled in recent years late pleistocene barriers significantly influenced present coastal landforms in two extensive regions dramatic changes in past decades indicate that sea level rise and stormier future hydroclimate may likely accelerate the degradation of deltaic and non deltaic barrier islands

shoreface sand supply to beaches the possibility of sand supply from the shoreface to beaches was evaluated based on a variety of methods involving field data and modeling results obtained from five coasts on three continents representing a wide range of coastal environments the field data include wave current measurements historical seabed soundings and geological surveys cross shore transport estimates from modeling on the annual time scale were compared against scaled down inferences from the seabed change and geological data the results are all consistent with there being net onshore transport over the long term from the lower shoreface to beaches in each of the environments these environments typify settings that occur commonly probably predominantly along the world s coasts so net shoreface sand supply to beaches may be a widespread and common but little appreciated factor in coastal stability the effect of this net supply is to offset other factors causing shoreline recession such as positive gradients in littoral transport moreover shoreline progradation occurs if sand supply from the shoreface dominates over littoral sediment losses implications are clearly significant for coastal engineering and coastal management despite the processes not being immediately apparent long term shoreface sand supply to beaches is masked by more rapid cyclical changes rates of shoreface sand supply to beaches indicated from various lines of evidence are typically on the order of 10 0 m 3 a 1 per meter of shoreline this volume corresponds to a lowering of the shoreface by only a few grain diameters per year

an insight into headland sand bypassing and wave climate variability from shoreface bathymetric change at byron bay new south wales australia abstract the headland sand bypassing mechanisms in the eastern australian longshore sand transport system are investigated at cape byron in response to wave climate variability the mechanisms are interpreted from shoreface bathymetric change between surveys in 1883 2002 and 2011 ce they involve a split in the sand transport to follow a nearshore path along the inner bar and a cross embayment path connecting the up coast and down coast outer bars the relative magnitude of the net sand transported via the two pathways is controlled by a rotation in directional wave conditions two bypassing mechanisms were interpreted i a predominantly cross embayment transport during unimodal east southeast wave climate such as those interpreted for the period prior to 1883 and ii a split transport between the inner nearshore and cross embayment paths during a bimodal dominant south south easterly and sub dominant east north easterly wave climate such as in the 2000s the net sand transport bypassing cape byron was dominated by a connected outer bar system prior to 1883 and conversely a stronger inner bar system during the 1960s to 2000s this is manifest in the 10 rotation in seabed morphology and shoreline planforms these changes are in accordance with decadal climate variability described by the interdecadal pacific oscillation ipo the switching between headland sand bypassing mechanisms on interannual to decadal timescales determines the geometry of the bypass strand with the downcoast littoral zone and has important implications for understanding the shoreline rotation and the application of the headland bay beach concept to predicting planform curvature in open compartments

holocene evolution of the wave dominated embayed moruya coastline southeastern australia sediment sources transport rates and alongshore interconnectivity abstract sediment budgets on wave dominated coastlines are important in determining shoreline behaviour and are primarily inherited from geological scale coastal evolutionary history sediment compartments provide a framework to conceptualise and investigate sediment budgets over a range of time and space scales this study aims to assess the sediment budget for a secondary coastal compartment on the new south wales nsw south coast 26 km in length and containing five adjacent but discrete holocene coastal bay barriers barlings beach broulee beach bengello beach moruya heads beach and pedro beach building on earlier morphostratigraphic studies a new series of optically stimulated luminescence osl ages are presented for foredune ridge sequences at previously un dated sites additional ground penetrating radar gpr transects complement earlier stratigraphic datasets and seamless topographic and bathymetric lidar datasets provide insight into subaerial coastal deposits and inner shelf morphology in this region the results demonstrate that barriers within the compartment have two different sediment sources the barriers are dominated by shoreface supply of quartz rich sand transported onshore as shoreface morphology evolved towards equilibrium skeletal carbonate sand became an important component of the sediment budget for the northern barlings and broulee beaches after 3000 years ago shoreline progradation at bengello beach has been steady throughout the mid to late holocene bengello contains the largest volume of holocene sand and accreted at an average rate of 3 1 m3 m yr for the current shoreline length the other barrier systems have experienced changes in sediment accumulation rate as their shorelines prograded seaward resulting in changes to their alongshore interconnectivity rapid filling of the pedro beach embayment by 4000 years ago initiated headland bypassing and northward sand transport to moruya heads beach which only then commenced progradation in contrast as broulee and bengello beaches prograded they converged in the lee of broulee island forming a tombolo which led to division of the former continuous shoreline into two a marked increase in skeletal carbonate content at broulee occurred after this separation attesting to the restriction of the southern quartz sand source replaced by local carbonate production this study emphasises the importance of understanding the long term temporal variability in sediment budget and embayment interconnectivity in determining shoreline response to changing boundary conditions such as sea level and wave climate as well as contemporary anthropogenic influences

active faulting and natural hazards in armenia eastern turkey and northwestern iran active fault zones of armenia se turkey and nw iran present a diverse set of interrelated natural hazards three regional case studies in this cross border zone are examined to show how earthquakes interact with other hazards to increase the risk of natural disaster in northern armenia a combination of several natural and man made phenomena earthquakes landslides and unstable dams with toxic wastes along the pambak sevan sunik fault pssf zone lowers from 0 4 to 0 2 0 3g the maximum permissible level mpl of seismic hazard that may induce disastrous destruction and loss of life in the adjacent vanadzor depression in the ararat depression a large active fault bounded pull apart basin at the junction of borders of armenia turkey iran and azerbaijan an earthquake in 1840 was accompanied by an eruption of ararat volcano lahars landslides floods soil subsidence and liquefaction the case study demonstrates that natural hazards that are secondary with respect to earthquakes may considerably increase the damage and the casualties and increase the risk associated with the seismic impact the north tabriz gailatu fault system poses a high seismic hazard to the border areas of nw iran eastern turkey nakhichevan azerbaijan and southern armenia right lateral strike slip motions along the north tabriz fault have given rise to strong earthquakes which threaten the city of tabriz with its population of 1 2 million the examples illustrate how the concentration of natural hazards in active fault zones increases the risk associated with strong earthquakes in armenia eastern turkey and nw iran this generally occurs across the junctions of international borders hence the transboundary character of active faults requires transboundary cooperation in the study and mitigation of the natural risk

gebel kamil the iron meteorite that formed the kamil crater egypt abstract the 45 m in diameter kamil impact crater was formed 10 g inferred from the density map compiled in this study is 3400 kg field data indicate that the iron bolide approached the earth s crust from the northwest 305 340 n travelling along a moderately oblique trajectory upon hypervelocity impact the projectile was disrupted into thousands of fragments shattering was accompanied by some melting of the projectile and of the quartz arenite target rocks which also suffered shock metamorphism

rapid relative sea level fall along north eastern australia between 1200 and 800 cal yr bp an appraisal of the oyster evidence a fast paced post glacial sea level rise and subsequent mid holocene sea level highstand are well documented at several far field locations away from the presence of former ice sheets but sea level development during the late holocene remains ambiguous in this study we present new data from modern and fossil oysters attached to shoreline rocks along the north eastern australian coastline that reveal new constraints on the nature and timing of relative sea level change over the past 2500 yr surveyed elevations of various contemporary oyster zones contextualize modern oyster growth forms in relation to sea level datum and build the reference for our fossil oyster data based on survey data and field observations we developed a robust set of criteria for measuring fossil oysters to determine their relative sea level position and constrain the uncertainties associated with these reconstructions thick 10 cm fossil oyster visors above the equivalent modern growth suggest higher relative sea levels in the past i e 1200 cal yr bp radiocarbon analyses of the modern oyster visors suggest continuous lateral accumulation over the past 800 yr which implies relatively stable sea level over this period the modern and fossil dataset defines a distinct and rapid relative 1 m sea level fall between 1200 and 800 cal yr bp whether the sea level fall was stepped or followed a broader smooth monotonic pattern is unclear the timing coincides with the initiation of some inshore fringing coral reefs in the great barrier reef region and other major geomorphological changes along the coastal zone a combination of various factors may have been the driving mechanism behind this relative sea level fall with rates between 1 0 to 5 2 mm yr 1

wave climate sand budget and shoreline alignment evolution of the iluka woody bay sand barrier northern new south wales australia since 3000 yr bp abstract multi centennial fluctuations in the northern new south wales nsw coastline alignment are interpreted from a detailed reconstruction of the morphological and depositional evolution of the iluka to woody bay barrier during the late holocene the regional coastline is aligned obliquely to the south east inner shelf modal wave direction and hence sediment is transported obliquely on the shoreface with a net northward movement on centennial to millennial time scales the coastline is shown to have responded to fluctuations in mean wave direction longshore gradients in sand transport and headland sand bypassing processes overall barrier progradation has been punctuated by episodes of shoreline recession and realignment throughout the late holocene a prolonged shoreline recessional phase occurred at 1500 yr bp in response to a rotation in modal wave direction from more southerly towards east south easterly subsequent to this realignment renewed shoreline progradation occurred along the east aspect coastline after 1400 yr bp whilst the north east aspect coastline remained in a receded alignment until after 1000 yr bp when renewed progradation occurred progradation rates increased throughout the past millennium driven by changes to the alongshore gradient in sand transport under an implied shift to a more southerly and energetic modal wave climate in the past 50 yrs the north east aspect shoreline has experienced a rapid recessional trend which is associated with a shift in modal wave climate to a more east southeasterly direction and a reduction in headland sand bypassing the average sand supply rate to the iluka to woody head section of the northern nsw shoreline is 4 1 m3 m yr since 3000 yr bp

towards more robust chronologies of coastal progradation optically stimulated luminescence ages for the coastal plain at moruya south eastern australia accurate chronologies are fundamental for detailed analysis of palaeoenvironmental conditions archaeological reconstructions and investigations of holocene coastal morphological changes chronolog

enso to multi decadal time scale changes in east australian current transports and fort denison sea level oceanic rossby waves as the connecting mechanism the connection between east australian current eac transport variability and australia s east coast sea level has received little treatment in the literature this is due in part to the complex interacting physical processes operating in the coastal zone combined with the sparsity of observations available to improve our understanding of these possible connections this study demonstrates a statistically significant at the 490 level relationship between interannual to decadal time scale variations in observed estimates of the eac transport changes and east coast sea level measured at the high quality long record fort denison tide gauge in sydney harbour australia 3315101800s 15111303200e we further demonstrate using a linear reduced gravity ocean model that enso to decadal time scale variations and the ocean adjusted multi decadal trend approx 1 cm decade in observed sea level at fort denison are strongly connected to modulations of eac transports by incoming westward propagating oceanic rossby waves we show that eac transport and fort denison sea level vary in a manner expected from both tasman sea generated rossby waves which account for the interannual and multi annual variability and remotely forced from east of new zealand rossby wave connections through the mid latitudes accounting for the ocean adjusted multi decadal trend observed at the new south wales coast with the regional tasman sea forcing explaining the greatest overall proportion of eac transport and sea level variances

influence of climate fluctuations and changes in catchment land use on late holocene and modern beach ridge sedimentation on a tropical macrotidal coast keppel bay queensland australia abstract beach ridges at keppel bay central queensland australia preserve a record of sediment accumulation from the historical period back to middle holocene times the ridges comprise fine well sorted feldspar rich quartz sand that was eroded from the fitzroy river catchment deposited in keppel bay during floods of the fitzroy river and reworked onshore into beach and foredune deposits by the prevailing currents waves and wind these floods have an average recurrence interval of at least 7 yr and are induced by the passage of cyclones onshore into the large fitzroy catchment the youngest series of beach ridges sit sub parallel to the modern beach and comprise six accretional units each unit formed by a set of ridges and delineated by prominent swales optically stimulated luminescence osl ages of beach ridges in these units indicate they were deposited in periods of rapid progradation approximately 1500 1000 450 and 230 yr bp when there was an enhanced supply of sediment to the beach from the fitzroy river via keppel bay estimates of the mass of sediment stored in the beach ridge strandplain show that it represents a significant sediment store potentially trapping the equivalent of 79 of the estimated long term 100 yr average annual bedload of the fitzroy river that is deposited in keppel bay there has been a reduction in the rate of sediment accumulation in the strandplain since around 1000 yr bp which is consistent with other coastal records in eastern australia of a relatively wetter phase of climate in the late holocene compared to the present the youngest beach ridges osl ages

optical dating of holocene sediments from a variety of geomorphic settings using single grains of quartz this paper presents an improved method for the optical dating of holocene sediments from a variety of geomorphic settings we have measured the equivalent dose de in individual grains of quartz using green laser light for optical stimulation and have simulated the de distributions for multiple grain synthetic aliquots using the single grain data for 12 samples of known independent age we show that application of a minimum age model to the single grain and small 10 grain aliquot de data provides the most accurate estimate of the burial dose for nine of the samples examined 3 aeolian 5 fluvial and 1 marine the weighted mean de as obtained using the central age model gives rise to burial age overestimates of up to a factor of 10 for these nine samples whether single grains small aliquots or large 100 grain aliquots are used for the other three samples two aeolian and one fluvial application of either the minimum age model or the central age model to the single grain small aliquot and large aliquot de data yields burial ages in accord with the independent age control we infer that these three samples were well bleached at the time of deposition these results show that heterogeneous bleaching of the optical dating signal is commonplace in nature and that aeolian transport offers no guarantee that the sample will be well bleached at the time of deposition we also show that grains sensitive to infrared ir stimulation can give rise to low de values which will result in significant underestimation of the burial dose and hence of the age of deposition we demonstrate that use of a modified single aliquot regenerative dose protocol incorporating ir stimulation prior to green light stimulation deals effectively with contamination by ir sensitive grains we conclude that application of the modified protocol to single grains or small aliquots of quartz using the lowest de population to estimate the burial dose is the best means of obtaining reliable ages for holocene sediments from a wide range of depositional environments d 2003 elsevier b v all rights reserved

determination of controls on holocene barrier progradation through application of osl dating the ilha comprida barrier example southeastern brazil abstract barrier development during the holocene is studied using the example of the ilha comprida southeastern brazil aerial photos facies analysis and optically stimulated luminescence dating are used to define the barrier emergence and evolution optically stimulated luminescence ages and facies successions indicate that the ilha comprida probably began as a holocene transgressive barrier island 6000 years ago just before the last relative sea level maximum since then the barrier has progradated through the addition of curved beach ridges based on beach ridge alignments six units of growth are identified with two growth directions transverse and longitudinal rates of progradation with transverse growth vary from 0 13 to 4 6 m year rates of longitudinal growth to ne range from 5 2 to 30 m year variation in coastal progradation rates and sediment retention during the last 6000 years is compared with climate physiography and relative sea level changes the physiography represented by pre cenozoic hills is the major control on sediment retention and alternation between longitudinal and transverse growth climate variations such as the little ice age event apparently control the formation of ridges types beach ridges foredunes and blowouts these results allow the use of the ilha comprida barrier as an example to analyze the major controls on barriers progradation

noble gases in mineral separates from three shergottites shergotty zagami and eeta79001 this study provides a complete data set of all five noble gases for bulk samples and mineral separates from three martian shergottites shergotty bulk pyroxene maskelynite zagami bulk pyroxene maskelynite and elephant moraine eet a79001 lithology a bulk pyroxene we also give a compilation of all noble gas and nitrogen studies performed on these meteorites our mean values for cosmic ray exposure ages from 3he 21ne and 38ar are 2 48 myr for shergotty 2 73 myr for zagami and 0 65 myr for eeta79001 lith a serious loss of radiogenic 4he due to shock is observed cosmogenic neon results for bulk samples from 13 martian meteorites new data and literature data are used in addition to the mineral separates of this study in a new approach to explore evidence of solar cosmic ray effects while a contribution of this low energy irradiation is strongly indicated for all of the shergottites spallation ne in chassigny allan hills alh 84001 and the nakhlites is fully explained by galactic cosmic ray spallation implanted martian atmospheric gases are present in all mineral separates and the thermal release indicates a near surface siting we derive an estimate for the 40ar 36ar ratio of the martian interior component by subtracting from measured ar in the k poor pyroxenes the small radiogenic component as well as the implanted atmospheric component as indicated from 129xe excesses unless compromised by the presence of additional components a high ratio of 2000 is indicated for martian interior argon similar to that in the martian atmosphere since much lower ratios have been inferred for chassigny and alh 84001 the result may indicate spatial and or temporal variations of 40ar 36ar in the martian mantle

terrestrial ages pairing and concentration mechanism of antarctic chondrites from frontier mountain northern victoria land we report concentrations of cosmogenic 10be 26al 36cl and 41ca in the metal phase of 26 ordinary chondrites from frontier mountain fro antarctica as well as cosmogenic 14c in eight and noble gases in four bulk samples thirteen out of 14 selected h chondrites belong to two previously identified pairing groups fro 90001 and fro 90174 with terrestrial ages of 40 and 100 kyr respectively the fro 90174 shower is a heterogeneous h3 6 chondrite breccia that probably includes more than 300 individual fragments explaining the high h l chondrite ratio 3 8 at frontier mountain the geographic distribution of 19 fragments of this shower constrains ice fluctuations over the past 50 100 kyr to less than 40 m supporting the stability of the meteorite trap over the last glacial cycle the second h chondrite pairing group fro 90001 is much smaller and its geographic distribution is mainly controlled by wind transport most l chondrites are younger than 50 kyr except for the fro 93009 01172 pair which has a terrestrial age of 500 kyr these two old l chondrites represent the only surviving members of a large shower with a similar preatmospheric radius 80 cm as the fro 90174 shower the find locations of these two paired l chondrite fragments on opposite sides of frontier mountain confirm the general glaciological model in which the two ice flows passing both ends of the mountain are derived from the same source area on the plateau the 50 fro meteorites analyzed so far represent 21 different falls the terrestrial ages range from 6 kyr to 500 kyr supporting the earlier proposed concentration mechanism

a reconstruction of extratropical indo pacific sea level pressure patterns during the medieval climate anomaly subtropical and extratropical proxy records of wind field sea level pressure slp temperature and hydrological anomalies from south africa australia new zealand patagonian south america and antarctica were used to reconstruct the indo pacific extratropical southern hemisphere sea level pressure anomaly slpa fields for the medieval climate anomaly mca 700 1350 ce and transition to the little ice age lia 1350 1450 ce the multivariate array of proxy data were simultaneously evaluated against global climate model output in order to identify climate state analogues that are most consistent with the majority of proxy data the mean slp and slp anomaly patterns derived from these analogues illustrate the evolution of low frequency changes in the extratropics the indo pacific extratropical mean climate state was dominated by a strong tropical interaction with antarctica emanating from 1 the eastern indian and south west pacific regions prior to 1100 ce then 2 the eastern pacific evolving to the central pacific la nina like pattern interacting with a ve sam to 1300 ce a relatively abrupt shift to ve sam and the central pacific el nino like pattern occurred at 1300 a poleward equatorward shift in the subtropical ridge occurred during the mca mca lia transition the hadley cell expansion in the australian and southwest pacific region together with the poleward shift of the zonal westerlies is contemporaneous with previously reported hadley cell expansion in the north pacific and atlantic regions and suggests that bipolar climate symmetry was a feature of the mca

transition from marine to fluvial dominated sediment supply at shoalhaven prograded barrier southeastern australia abstract prograded barriers are depositional coastal landforms which have the potential to reveal changes in the primary drivers of coastal evolution within their varied morphology beach ridges and intervening swales preserve paleoenvironmental records of coastal processes relative sea level and storm events optically stimulated luminescence osl dating of quartz grains airborne lidar derived morphology and sediment texture and mineralogy reveal four different periods of morpho sedimentary progradation history in the shoalhaven barrier system in southeastern australia the barrier is composed of approximately 40 ridges that occupy an area of 15 2 km2 comprising an estimated sand volume of approximately 88 000 000 m3 above mean sea level osl dating of ten samples taken from a 940 m long transect across the holocene system indicated that the barrier prograded at a slow rate of approximately 0 12 m yr from 6130 330 to 2400 130 years ago and subsequently at a higher rate of 0 22 m yr until 600 130 years ago more recently an increase in historical accumulation and progradation rates has favoured development of an anomalously high foredune fronting the system with the formation of lower ridges in the past two centuries increasing angularity and feldspar content observed via scanning electron microscope sem and determined using x ray diffraction xrd analysis respectively imply a transition in sediment supply progradation has been sustained through delivery and reworking of marine sediments from offshore following the marine transgression subsequently augmented by fluvial sands discharged to the coast by the shoalhaven river the adjustment in progradational rates and sediment provenance influenced the morphology and spacing of individual ridges and the regressive system as a whole average progradation rates for the shoalhaven barrier revised from those previously reported using radiocarbon dating are considered lower than most of barriers studied in similar coastal environments around australia indicating the different ways that similar progradation systems have evolved

induced seismicity around the tous new dam spain summary induced seismicity around the tous new dam located 45 km southwest of valencia spain is studied from a detailed analysis of seismic data from a 16 month period starting in 1999 january recorded by the tous new dam seismic network tdsn which comprises a threecomponent station located in the dam and six vertical component outstations within 25 km of the dam on the basis of the spatial 2d 3d and temporal distribution of this seismicity we have found 24 microearthquakes of magnitudes 0 4 3 8 most of which appear correlated in time and space with changes in the water level in the tous new dam reservoir an initial group of earthquakes all within 12 km or less of the reservoir occurred over roughly 1 yr starting in mid 1999 while the water level was at its maximum continuing during draining in late 1999 and subsequent refilling in early 2000 thereafter seismicity was more widespread reaching up to 40 km from the dam and with the greatest frequency of occurrence coinciding with the rapid draining of the reservoir in mid 2000 the few focal mechanisms able to be found are normal or strike slip in general it is clear that a relationship exists between reservoir water level which probably modifies the pre existing tectonic stress field and pore fluid pressures but no specific mechanism for the induced seismicity has yet been identified

geomorphological control on podzolisation an example from a tropical barrier island abstract we investigated how the geomorphology of coastal barrier islands impacts soil hydrology and drainage at the landscape scale ilha comprida is a holocene barrier island with a 2 5 km long cliff that is perpendicular to the coastal shore which provides an ideal condition to study the relation between age relief hydrology and podzol morphology five geomorphic units were identified that differed in surface morphology and alignment of ridges and swales optical stimulated luminescence osl dating showed that these geomorphic units had growth phases that decreased in age from west to east units i v from 5250 820 to 325 31 years ago respectively the geomorphic units were studied in two parallel 3 km transects on the southern part of the island along transect a b about 1 km from the southern shore deep augerings were used to study sedimentary sequence and soil development while on transect c d on the southern shore the continuous cliff exposure allowed more detailed morphological investigation on all geomorphic units excluding the youngest podzolisation has been the main soil forming process groundwater level was monitored monthly for two years in 14 deep wells along transect a b groundwater level during the formation of the b horizon was ascertained by determination of fe podzol morphology color of b horizon and its boundary with the e horizon generally showed correlation to groundwater levels for both transects except for the podzols in southwestern part of the island unit ii the podzols of unit ii showed an extremely thick 3 m bhm horizon devoid of fe indicating that they were formed under poor drainage conditions however soil morphology undulating eb horizon boundary and measured groundwater levels below the b horizons demonstrated that drainage has been improved the extremely thick b horizon 3 m in those podzols which was formed in approximately 3000 years and its genesis is explained by concentrated lateral flow of dom loaded groundwater due to the converging ridge alignments found in these units in combination with a gradual uplift of the southwestern part of the island

twenty years seismic monitoring of induced seismicity in northern albania the northern part of albania has been the focus of an intense effort by the seismological institute of albania for in this area two of the country s biggest reservoirs are located three years before the impounding of the fierza reservoir a four station network was installed around it the possibility of induced seismicity continued after the impoundment of the fierza reservoir in 1978 and the komani reservoir in 1985 the seismicity of the zone and some aspects of induced seismicity including temporal correlation of seismicity with water level changes spatial patterns in seismicity frequency magnitude relations fault plane solutions etc are studied during this period the presence in this zone of a very important transverse fault the shkoder peja fault makes the study of induced seismicity from fierza and komani reservoirs even more significant the studies have shown that the impounding of the fierza and komani reservoirs has modified the natural course of microearthquake energy release increasing the number of swarms in this area

origins of holocene coastal strandplains in southeast australia shoreface sand supply driven by disequilibrium morphology abstract coastal barriers store depositional records of past environmental conditions such as sea level wave climate and sedimentary regime the embayed highstand coast of southeast australia features a diverse range of coastal sand barriers suggesting varying depositional responses to holocene environmental conditions in particular the varying chronologies of prograded barrier strandplains along a passive margin with a predominantly autochthonous sedimentary regime raises questions about relative sea level change and sediment sharing within and between compartments during the holocene here we apply detailed geological data and geochronology from the holocene prograded barrier system at tuncurry within a morphodynamic modelling approach to investigate the depositional response of the coastal system to possible drivers of strandplain growth including 1 forced regression driven by mid to late holocene relative sea level fall 2 time varying external sand supply via the alongshore transport system and 3 shoreface sand supply in response to disequilibrium morphology and stable sea level comparison between the simulated depositional response of the coastal system and the geological records suggests that progressively weakening and depth decaying shoreface sand supply in response to disequilibrium morphology was the primary driver of holocene strandplain growth alongshore sand transport into the tuncurry compartment via a headland attached shelf sand body may have provided a secondary sand source although the simulated barrier shoreface evolution precludes a dominant external sand supply mid to late holocene sea level fall from a highstand level within the range of uncertainty in available indicators 1 5 m above present could only have contributed a minor portion of strandplain growth by process of forced regression the simulations demonstrate the potential sensitivity of strandplain chronologies to the sampling location i e shoreface or dune facies which emerges from coupled barrier shoreface evolution that may support time decaying volumetric growth and steady shoreline progradation simultaneously shoreface sand supply driven by the ongoing relaxation of disequilibrium morphology may persist at subtle rates 1 2 m3 m yr today on some southeast australian beaches promoting shoreline stability and potentially moderating initial shoreline response to sea level rise

geochronology and evolution of a complex barrier younghusband peninsula south australia abstract this study examines the southeastern end of the younghusband peninsula in south australia at a location called the granites in order to gain a better understanding of the processes of formation of the foredune ridge system and to investigate the drivers that controlled its progradational development during the holocene our findings are based on a morphological analysis a ground penetrating radar survey and 14c and osl dating the younghusband peninsula at the granites was formed by an initial aggradational phase resulting in a single complex foredune ridge and which ended around 4 3 ka and by a regressive progradational barrier phase 750 m wide that developed in the last 4 3 ka under very low rates of progradation 0 38 to 0 09 m yr the last part of this phase shows significant foredune ridge building in the last 1000 years or so barrier progradation via foredune ridge development is likely an effect driven by low wave energy that favored conditions for coastal stability and foredune formation paleontological and gpr data indicate a maximum sea level of 1 23 to 1 5 m respectively during initial barrier development the foredune ridge plain of the barrier experienced at least three phases of significant aeolian activity with ages centered at around 3 9 3 4 and 3 0 ka suggesting their occurrence at 500 to 400 year events computer modelling indicates that sediments for the progradational phase of the barrier were provided by the forced regression produced by a sea level fall over the past 4 3 ka the large foredune complex formed during the last phase of progradation could be the result of both the very low progradation rate of 0 09 m yr and periods of disturbance possibly related to enhanced storm activity

relative sea level records preserved in holocene beach ridge strandplains an example from tropical northeastern australia abstract northeastern queensland is a far field site from ice caps formed during the last glacial however the region has experienced glacio hydroisostatically driven coastal elevation change during the holocene that generated a distinctive relative sea level record we tested whether this subtle vertical movement of the coast is recorded in the morphology and stratigraphy of the beach ridge strandplain at cowley beach which comprises a series of 36 prominent and several subdued or truncated beach ridges previous studies have shown that the strandplain records the long term progradation of the coast with the ridges comprising coarse medium sand that was deposited during both fairweather foreshore and berm facies and tropical cyclone events erosional unconformities storm surge deposits over the past approximately 7 ka we utilised a fine scale digital elevation model of the strandplain to examine beach ridge morphology and to compare the elevation pattern with published holocene sea level data for the region the overall elevation pattern of the strandplain surface is consistent with the regional sea level history that includes a highstand at around 6 ka bp generated by isostatic uplift and the elevation of the berm facies matches well robust coral sea level indicator data we also modelled the strandplain topographic patterns that would result under stable and continually rising holocene sea levels the frequencies of elevation classes across the strandplain are normally distributed when the strandplain is deposited during a period of stable sea level and negatively skewed with a continually rising sea level consistent with the expected patterns the results indicate the sensitivity of the elevation of the top of the berm facies preserved in beach ridges to subtle changes in sea level tens of cm over a thousand years our results further underline the utility of beach ridge strandplains a globally distributed coastal landform for building relatively detailed regional records of sea level during the holocene at sites currently lacking this information

evolution from estuary to delta alluvial plain morphology and sedimentary characteristics of the shoalhaven river mouth southeastern australia abstract the shoalhaven river in southern new south wales nsw drains a catchment of 7000 km2 forming a barrier estuary at its mouth with a prograded strandplain to its north previous coring and dating across the floodplain and adjacent strandplain indicate progressive infill of the estuarine basin over the past 7000 years over this time the system transitioned from a wave dominated estuary to a wave dominated delta the shoalhaven river appears to have initially discharged to the sea at crookhaven heads until it adopted a more direct route through an intermittently open mouth at shoalhaven heads construction of berrys canal in 1822 now permanently links the shoalhaven river to the adjacent smaller crookhaven river airborne lidar reveals details of topography of prominent levees and meander scroll bars that flank the lower reaches of the river and beach foredune ridges to the north sedimentological and mineralogical characteristics of modern sediment samples collected from the river channel the beach and the barrier reveal that the shoalhaven river is dominated by quartz sand along its predominantly straight course through the infilled estuarine plains this is in contrast to the tripartite classification of sedimentary depositional environments comprising sandy fluvial delta central mud basin and sandy marine barrier that characterised the initial wave dominated estuary 7000 years ago and is typical of most barrier estuaries in nsw grain size decreases downstream and sands have a higher feldspar content and angularity than is typical of marine sand that has been reworked in the nearshore this fluvially derived component is delivered to the coast intermittently by floods that re open shoalhaven heads as shown by retrospective analysis of aerial photography and satellite imagery grain size decreases with distance alongshore from the river mouth indicating that these sands are transported north by longshore drift to augment a gradual onshore delivery of sand within this coastal compartment scanning electron microscopy of selected grains implies that this fluvial sand has been contributing to incremental formation of beach ridges for much of the past 3000 years since the estuarine basin has been largely infilled with a slight detectable acceleration in the rate of progradation

coastal wetlands reveal a non synchronous island response to sea level change and a palaeostorm record from 5 5 kyr to present here we describe environmental change on lord howe island lhi 31 30 s 159 05 e over the last 5500 cal bp derived from the analysis of the accumulating sediments in four coastal wetlands grain size analyses loss on ignition loi and micrometre resolution x ray fluorescence xrf geochemical data were combined with 10 accelerator mass spectrometry ams 14c dates to determine a chronology of environmental change sedimentary coastal features were initiated on the drowned lhi basalt coastline after 4500 cal bp which was followed by gradual development of wetland environments from 4200 cal bp to present within this period a series of high intensity storm events are recorded perhaps related to low pressure systems including cyclones and east coast low ecl events a lack of synchronicity between the studied sites resulted from their position in the landscape relative to the coast features within the lagoon and greater sediment availability after 2800 cal bp as sediment filled sinks in the

internal architecture of mixed sand and gravel beach ridges miquelon langlade barrier nw atlantic abstract the internal architecture of a beach ridge system can provide clues into the processes involved in its formation detailed investigation of the mixed sand and gravel beach ridge plain on the miquelon langlade barrier northwest atlantic ocean south of newfoundland provides a better understanding of such sedimentary systems in terms of internal architecture depositional processes and driving mechanisms investigations of this regressive paraglacial barrier included the topographic rtk gps and ground penetrating radar 100 to 500 mhz antennae data collection orthophotographs and optically stimulated luminescence osl dating the miquelon langlade beach ridge plain is composed of two opposing progradational systems reflecting contrasting eastward and westward hydrodynamic exposures four ridge sets each with concave planform shapes define the 500 1400 m wide eastward prograding plain along the sheltered eastern coast two ridge sets with linear and fan shaped planforms define the 200 500 m wide south westward prograding plain along the energetic western coast beach ridge units overlay a basal sedimentary unit that disrupted incoming wave energy and altered the planform morphology of the prograding plain the internal architecture pattern of individual beach ridges are characterized by sigmoidal configurations with seaward dipping beds 2 3 4 7 true dip angles it is proposed that these wave built facies are deposited as beach berms likely by fair weather waves the elevations of these facies are determined by the sea level elevation and the swash height of constructive waves during their formation beach ridges are overlain by either peat resulting from the flooding of topographically low lying areas or by aeolian sand deposits of varying heights and morphologies relict foredunes despite the differences in wave exposure along each coast the sedimentary composition and internal architecture of the two progradational systems are broadly similar bed dip angles of the individual beach ridges differ by only 1 2 steeper along the exposed westward facing coast overall the miquelon langlade beach ridge plain highlights the primary influences of wave exposure inherited topography and proximal sediment sources from erosion of moraines on coastal progradational patterns

monsoon influenced variations in morphology and sediment of a mesotidal beach on the mekong river delta coast abstract a mesotidal beach on the mekong river delta coast exhibits unique patterns of river sediment discharge and experiences reversals of ocean wave directions in response to the summer and winter monsoons we analyzed long term changes of the shoreline since 1936 from past topographic maps and satellite images and short term changes in geomorphology and sedimentology by undertaking repeated field surveys between november 2005 and february 2008 along six shore normal beach transects the shoreline of the mekong river delta coast has changed asymmetrically over the last 70 years in response to net southwestward sediment transport related to dry northeasterly winter monsoons during the summer rainy season large volumes of sediments are discharged from the river at this time wave direction is reversed in response to the relatively weak southwesterly summer monsoon mud and very fine sand in the surface sediments of the northeastern updrift beach transects tend to be removed during winter suggesting that the sediment supplied from the river during summer is temporarily deposited near the river mouth and later transported southwestward during the winter monsoon the relief of intertidal bars on the beach increased during winter in response to higher waves however previous studies have suggested that higher waves flatten bars we hypothesize that the increase in relief that we observed is related to a wide and shallow subtidal delta front platform that attenuates ocean waves at all times other than at high tide the beach profile varies longshore the accreting to stable beach dips seaward at a gradient of about 1 80 with up to three longshore intertidal bars classified here as either slip face bars or low amplitude ridges in contrast the eroding beach profile is much steeper 1 20 1 40 and linear without intertidal bars and is similar in form to a low tide terrace because there is little variation of wave size and grain size within the study area we consider that the spatial variation of the beach profile is related to the availability of sediment accumulated on the beach

noble gases in the xinjiang armanty iron meteorite a big object with a short cosmic ray exposure age abstract we measured the concentrations and isotopic ratios of the cosmogenic noble gases he ne and ar in the very large iron meteorite xinjiang iiie the 3he and 4he data indicate that a significant portion of the cosmogenic produced helium has been lost via diffusion or in a recent impact event high 22ne 21ne ratios indicate that contributions to the cosmogenic 21ne from sulfur and or phosphorous are significant by combining the measured nuclide concentrations with model calculations for iron meteorites we were able to determine the preatmospheric diameter of xinjiang to 260 320 cm which corresponds to a total mass of about 70 135 tons the cosmic ray exposure age of xinjiang is 62 16 ma i e relatively short compared to most of the other iron meteorites with the current database we cannot firmly determine whether xinjiang experienced a complex irradiation history the finding of 3he and 4he losses might argue for a recent impact event and therefore for a complex exposure

efficient disruption of small asteroids by earth s atmosphere accurate modelling of the interaction between the atmosphere and an incoming bolide is a complex task but crucial to determining the fraction of small asteroids that actually hit the earth s surface most semi analytical approaches have simplified the problem by considering the impactor as a strengthless liquid like object pancake models1 2 but recently a more realistic model has been developed that calculates motion aerodynamic loading and ablation for each separate particle or fragment in a disrupted impactor3 4 here we report the results of a large number of simulations in which we use both models to develop a statistical picture of atmosphere bolide interaction for iron and stony objects with initial diameters up to 1 km we show that the separated fragments model predicts the total atmospheric disruption of much larger stony bodies than previously thought in addition our data set of 1 000 simulated impacts combined with the known pre atmospheric flux of asteroids with diameters less than 1 km5 6 7 8 9 10 11 12 elucidates the flux of small bolides at the earth s surface we estimate that bodies 220 m in diameter will impact every 170 000 years

the development of blowouts and foredunes in the ilha comprida barrier southeastern brazil the influence of late holocene climate changes on coastal sedimentation abstract middle to late holocene barriers are conspicuous landforms in southeastern and southern brazilian regions the barriers in the coastal zones of northern santa catarina parana and sao paulo states 27 19 24 00 s are formed mainly by beach ridge alignments and many barriers present foredune and blowout alignments in their seaward portion the development of these eolian landforms appears to record a regional shift in coastal dynamics and barrier building in this context the ilha comprida barrier stands out for its well developed and well preserved foredunes and blowouts based on the presence or not and type of eolian landforms the ilha comprida barrier can be divided seaward into inner middle and outer units the inner unit is formed entirely by beach ridges the middle unit comprises a narrow belt of blowouts up to 15 m high aligned alongshore blowout lobes pointing nnw are indicative of their generation by southern winds the outer unit is represented by low 1 m high active or stabilized foredunes and a small transgressive dunefield 1 km 2 twenty seven luminescence ages sar protocol obtained for the beach ridges foredunes and blowouts of these three units allow definition of a precise chronology of these landforms and calculation of rates of coastal progradation the inner unit presents ages greater than 1004 88 years the blowouts of the middle unit show ages from 575 47 to 172 18 years the ages of the outer unit are less than 108 10 years rates of coastal progradation for the inner and outer units are 0 71 0 82 m year and 0 86 2 23 m year respectively the main phase of blowout development correlates well with the little ice age lia climatic event these results indicate that southern winds in subtropical brazil became increasingly more intense and or frequent during the lia these conditions persist to the present and are responsible for the development of the eolian landforms in the outer unit thus barrier geomorphology can record global climatic events the sensitivity of barrier systems in subtropical brazil to late holocene climate changes was favored by the relative sea level stillstand during this time luminescence dating makes it possible to analyze barrier geomorphology during late holocene climate changes operating on timescales of a hundred to thousand years these results improve our knowledge of barrier building and will help in the evaluation of the impact of future climate changes on coastal settings

the kamil crater in egypt we report on the detection in southern egypt of an impact crater 45 meters in diameter with a pristine rayed structure such pristine structures are typically observed on atmosphereless rocky or icy planetary bodies in the solar system this feature and the association with an iron meteorite impactor and shock metamorphism provides a unique picture of small scale hypervelocity impacts on earth s crust contrary to current geophysical models ground data indicate that iron meteorites with masses of the order of tens of tons can penetrate the atmosphere without substantial fragmentation

punctuated transgression comment on oliver t s n donaldson p sharples c roach m and woodroffe c d punctuated progradation of the seven mile beach holocene barrier system southeastern tasmania abstract sea level rise is known to have emplaced incipient sandy barriers during post glacial marine transgression and these same barriers are forecast to erode or transgress as rising seas accelerate with global warming in order for a barrier to prograded over the intervening millennia a positive sediment budget must exist such that sand supplied to the coast is ample enough to fill the existing accommodation space embayment or a drop in sea level forced seaward progradation storms have long been understood to repeatedly punctuate progradation over days to decades oliver et al 2017a however present two periods of perceived pauses in progradation lasting centuries and millennia with each hiatus considered to have resulted from changes in sediment supply despite the sizable dataset the there are gaps in the stratigraphy and chronology of barrier formation during these two specific time periods in question 6500 to 3500 years ago and 500 years ago to present additionally the morphology representing barrier evolution during 6 5 3 5 ka is obscured by the selected rendering of the light detection and ranging lidar data and breaks in the topographic profiles extracted from the lidar reanalysis of this data within the context of existing literature indicate that seaward progradation slowed not paused between 6 5 to 3 5 ka while this is not surprising for a site with no active riverine or longshore sediment source the rapid progradation that follows is this transition and the timing do make sense within the context of a fall from a mid holocene highstand which is debated in this far field region of australia furthermore it is apparent that the last few centuries do not represent a hiatus in barrier deposition but rather a termination in progradation and transition to erosion and transgression the barrier is not likely to resume prograding seaward but continue to erode and transgress in the future due to the forecast acceleration in sea level rise and increase in storm intensity associated with global warming

effects of closure depth changes on coastal response to sea level rise insights from model experiments in southern brazil abstract this study focuses on the impacts of variable shoreface closure depth limits on coastal responses to increases in sea levels along a sandy barrier in southern brazil upper and lower shoreface limits for sediment exchanges are largely regulated by the wave climate and they tend to move offshore as the temporal scale increases therefore because closure depth limits are a source of uncertainty in simulations of coastal response to sea level rise to elucidate how important changes in these limits are under such conditions four simulation experiments were performed with variable combinations of upper and lower shoreface closure depth values direct methods for closure depth delineation require long term data sets with field surveys which are rarely available therefore indirect approaches are applied widely to calculate closure depth values here we apply hallermeier s equations using two wave data sources one measured via wave buoys and one modeled wave watch iii and simulating waves nearshore model wwiii swan evaluation of coastal response under rising sea levels was possible via application of an aggregated coastal modeling approach using the random shoreface translation model ranstm shoreline retreat distances resulting from each combination of upper hc and lower hi shoreface closure depth values cases in model simulations were compared case 1 hc 7 4 m hi 42 1 m case 2 hc 7 4 m hi 35 7 m case 3 hc 6 2 m hi 35 7 m and case 4 hc 6 2 m hi 42 1 m statistical analysis via the kruskal wallis test demonstrated that shoreline retreat was significantly affected at p

coarse sand beach ridges at cowley beach north eastern australia their formative processes and potential as records of tropical cyclone history storm surges generated by tropical cyclones have been considered a primary process for building coarse sand beach ridges along the north eastern queensland coast australia this interpretation has led to the development of palaeotempestology based on the beach ridges to better identify the sedimentary processes responsible for these ridges a high resolution chronostratigraphic analysis of a series of ridges was carried out at cowley beach queensland a meso tidal beach system with a 3 m tide range optically stimulated luminescence ages indicate that 10 ridges accreted seaward over the last 2500 to 2700 years the ridge crests sit 3 5 to 5 1 m above australian height datum ca mean sea level a ground penetrating radar profile shows two distinct radar facies both of which are dissected by truncation surfaces hummocky structures in the upper facies indicate that the nucleus of the beach ridge forms as a berm at 2 5 m australian height datum equivalent to the fair weather swash limit during high tide the lower facies comprises a sequence of seaward dipping reflections beach progradation thus occurs via fair weather wave accretion of sand with erosion by storm waves resulting in a sporadic sedimentary record the ridge deposits above the fair weather swash limit are primarily composed of coarse and medium sands with pumice gravels and are largely emplaced during surge events inundation of the ridges is more likely to occur in relation to a cyclone passing during high tide the ridges may also include an aeolian component as cyclonic winds can transport beach sand inland especially during low tide and some layers above 2 5 m australian height datum are finer than aeolian ripples found on the backshore coarse sand ridges at cowley beach are thus products of fair weather swash and cyclone inundation modulated by tides knowledge of this composite depositional process can better inform the development of robust palaeoenvironmental reconstructions from the ridges this article is protected by copyright all rights reserved

cosmic ray exposure and pre atmospheric size of the gebel kamil iron meteorite cosmogenic he ne and ar as well as the radionuclides 10be 26al 36cl 41ca 53mn and 60fe have been determined on samples from the gebel kamil ungrouped ni rich iron meteorite by noble gas mass spectrometry and accelerator mass spectrometry ams respectively the meteorite is associated with the kamil crater in southern egypt which is about 45 m in diameter samples originate from an individual large fragment individual as well as from shrapnel concentrations of all cosmogenic nuclides stable and radioactive are lower by a factor 3 4 in the shrapnel samples than in the individual assuming negligible 36cl decay during terrestrial residence indicated by the young crater age 85 cm i e a pre atmospheric mass 20 tons with a preferred radius of 115 120 cm 50 60 tons the analyzed samples came from a depth of approximately 20 cm individual and approximately 50 80 cm shrapnel the size of the gebel kamil meteoroid determined in this work is close to estimates based on impact cratering models combined with expectations for ablation during passage through the atmosphere folco et al 2010 2011

optical dating of sediments a new method for dating sediments is proposed which determines the time since the sediment was last exposed to sunlight an argon ion laser is used to excite electrons from thermally stable light sensitive traps and the subsequent luminescence used as a measure of the past radiation dose two sample sequences spanning the periods 0 700 kyr and 0 6 kyr show steadily increasing luminescence with age an age of 62 8 kyr is obtained for a silt radiocarbon dated at 58 8 0 3 kyr problems were found with two much younger samples