heavy metals in a contaminated australian estuary dispersion and accumulation trend very high concentrations of zn pb cu and cd occur in the muddy bottom sediments of lake macquarie a saline coastal lagoon in southeastern australia the trace metals emanate from industrial sources especially a lead zinc smelter at the northern end of the lake individual metal concentrations decrease progressively away from the source area but at differing rates zn is most mobile and cd appears to be deposited first they approach natural background levels in the southern part of the lake mn shows a reverse trend but ni co ag and fe rarely rise above background levels shallow cores in the lake bed penetrated a metal enriched surface zone 15 35 cm thick underlain by uncontaminated sediments with natural background metal concentrations sedimentation rates determined from radiocarbon ages on shells in the cores mainly range between 0 15 and 0 5 mm yr 1 over the 85 years since industrialization commenced less than 5 cm of mud has accumulated on the lake bed bioturbation is invoked to account for the depth to which the sediment has been enriched in heavy metals

geomorphological variability among microtidal estuaries from the wave dominated south african coast abstract over 300 independent river outlets exist around the microtidal wave dominated south african coast most of these are located in drowned river valley settings and have acquired their present morphology during the holocene marine transgression a variety of geomorphological forms are identified in these estuaries that result from variation in antecedent topography fluvial sediment supply and marine sediment supply five distinctive estuary types are identified on the basis of contemporary morphodynamics these are categorised into three types of normally open estuary that maintain a semi permanent connection with the open sea and two types of normally closed estuary which are separated from the sea for long periods by a continuous supratidal barrier the contemporary morphodynamics and sedimentary environments of each estuary type are discussed open estuaries include barrier inlet systems maintained by fluvial discharge termed river dominated estuaries and tidal discharge termed tide dominated estuaries a third category of open estuary lacks a supratidal barrier due to inadequate marine sediment availability closed estuaries receive marine influence via barrier overwash and occasional breaching but are typically enclosed behind a continuous supratidal barrier two categories of closed estuary are identified perched and non perched perched estuaries develop behind high berms and maintain a water level above high tide level in the open sea they are often dominated by fresh to brackish water and breach and drain periodically non perched estuaries are developed behind low elevation barriers fronted by wide dissipative beach profiles high overwash frequency introduces marine water into such systems breaching of such estuaries does not produce dramatic draining as the water level may only drop according to the stage of the open sea tidal cycle the variety of estuary types suggests several potential pathways may exist in estuarine development and that the progressive infilling model is an over simplification

facies evolution of holocene estuaries and deltas a large sample statistical study from australia abstract selected geomorphic features and sedimentary facies were mapped in 283 of australia s wave and tide dominated estuaries and deltas to quantitatively evaluate established evolutionary facies models that depict the evolution of estuaries into deltas during stable sea level conditions while diagnostic facies for wave and tide dominated estuaries and deltas approximate those specified by the models statistical analyses of the data also reveal two additional insights regarding the evolution of estuaries to deltas first there is an offshore shift in the locus of sand accumulation between tide dominated estuaries and deltas associated with the onset of delta development second the mean surface area of intertidal environments i e intertidal flats mangroves melaleuca saltmarsh salt flat facies is greater in wave dominated deltas than in wave dominated estuaries tidal penetration associated with the river establishing a more direct and permanent connection to the sea during late stage development presents a natural impediment to continued formation of an alluvial plain and full development of the classic wave dominated delta morphology a notional evolutionary pathway for wave dominated estuaries is developed from the distribution of facies that predicts the rate and susceptibility of geomorphic and habitat changes the classic deltaic geomorphology may be unattainable for wave dominated systems except those with significant terrigenous sediment inputs our study is the first published example of geomorphic and sedimentary data assembled from a large number of wave and tide dominated estuaries and deltas across an entire continent

holocene sea level change on the southeast coast of australia a review a revised holocene sea level curve for the southeast coast of new south wales australia is presented based on a review of previously published geochronological results for fossil molluscs organi

the holocene infill of lake conjola a narrow incised valley system on the southeast coast of australia a detailed holocene sedimentological and geomorphological history of the sedimentary infill of lake conjola a barrier estuary on the southeast coast of australia is presented results show that a remnant last interglacial barrier system is preserved in the mouth of a narrow incised valley during the early stage of holocene sedimentary infill a laterally extensive transgressive sand facies was deposited as rising post glacial sea level breached remnants of the last interglacial barrier ca 7500 cal bp from 7500 to 4000 cal bp sediment continued to accumulate within the mouth of the incised valley forming an extensive flood tide delta within the drowned river estuary marine influences were restricted by further sediment accumulation at the mouth of the estuary leading to the development of mid holocene barrier and back barrier depositional environments this research adds detail to stratigraphic models of the sedimentary infill and geomorphological evolution of barrier estuaries formed in narrow incised valley systems on the southeast coast of australia and provides a global model for estuarine deposition in regions that have been tectonically stable over the late quaternary

vertical variation of oxygen isotope in bay of bengal and its relationships with water masses 1 we present here for the first time comprehensive depth specific near surface to 1800 m oxygen isotope 18o data set of 175 water samples collected from 22 different locations in the bay of bengal bob during july august 2009 and december january 2012 2013 the study is aimed to constrain the water mass parameters using oxygen isotope and salinity four water masses are identified on the basis of temperature salinity relationship a bay of bengal water bobw 0 50 m b mixed zone mz 60 120 m c indonesian throughflow itf 200 500 m and d indian ocean deep water idw 600 1800 m our study shows 1 18o salinity correlation slope 0 15 0 01 intercept 4 58 0 24 r2 0 89 n 54 for the bobw is found to be consistent with surface bob water reported earlier 2 relatively lower correlation r2 0 24 n 47 in underlying mixed zone suggesting mixing of various water masses 3 significant linear correlation between 18o and salinity in idw r2 0 70 indicating depleted less saline water from southern hemisphere spread up to 18 n and 4 vertical profiles at various sampling locations showing a continuous enrichment of 18o 0 6 0 8 within top 60 100 m irrespective of their proximity to coastline in conjunction with a sharp decrease in 14c data below the same depth zone 60 100 m as reported earlier we suggest the 18o value reaches to its acme at a zone of mixing between younger bobw and relatively older itf this preliminary study indicates oxygen isotope and salinity together can be used to identify different water masses in the bob

determining the impact of the holocene highstand at the coastal fluvial interface shoalhaven river south eastern australia with enhanced rates of sea level rise predicted for the next century the upstream extent of sea level influence across coastal plains is a topic of public importance australian coastal rivers provide a testing ground for exploring this issue because the area is tectonically stable was not glaciated and experienced a holocene highstand between 7 4 and 2 ka of up to 1 5 m above australian height datum ahd in the shoalhaven river of new south wales investigation of a confined bedrock reach at wogamia 32 km inland has identified a unit of dark cohesive silt and sand with marine diatoms shell fragments and enhanced pyrite content interpreted as estuarine the unit is up to 13 m thick thickens downstream and is overlain by fluvial channel and floodplain deposits the estuarine unit on laps a remnant pleistocene terrace and extends to approximately 2 2 m ahd optically stimulated luminescence osl and radiocarbon ages suggest that estuarine deposition commenced prior to 7 8 ka cal bp predating the highstand by 500 years and that marine influence in the area continued to 5 3 0 7 ka during this period a delta probably persisted at wogamia where a narrow upstream reach opens out and subsequently advanced to fill the broad shoalhaven coastal embayment although the effect of sea level rise depends on many factors the results suggest that during a highstand at or above present sea level a strong marine influence may extend for tens of kilometres inland and penetrate confined bedrock reaches landward of coastal embayments copyright 2013 john wiley sons ltd

sedimentation in a river dominated estuary the mgeni estuary on the wave dominated east coast of south africa occupies a narrow bedrock confined alluvial valley and is partially blocked at the coast by an elongate sandy barrier fluvial sediment extends to the barrier and marine deposition is restricted to a small flood tidal delta sequential aerial photography sediment sampling and topographical surveys reveal a cyclical pattern of sedimentation that is mediated by severe fluvial floods which exceed normal energy thresholds during severe floods up to 10x 103 m3 s 1 lateral channel confinement promotes vertical erosion ofbed material eroded material is deposited as an ephemeral delta in the sea after floods the river gradient is restored within a few months through rapid fluvial deposition and formation of a shallow braided channel over an extended period approximately 70 years the estuary banks and bars are stabilised by vegetation and mud deposition subsequent downcutting in marginal areas transforms the channel to an anastomosing pattern which represents a stable morphology which adjusts to the normal range of hydrodynamic conditions this cyclical pattern of deposition produces multiple fill sequences in such estuaries under conditions of stable sea level the barrier and adjacent coastline prograde temporarily after major floods as the eroded barrier is reformed by wave action but excess sediment is ultimately eroded as waves adjust the barrier to an equilibrium plan form morphology deltaic progradation is prevented by a steep nearshore slope and rapid sediment dispersal by wave action and shelf currents during transgression estuarine sedimentation patterns are controlled by the balance between sedimentation rates and receiving basin volume if fluvial sedimentation keeps pace with the volume increase of a basin an estuary may remain shallow and river dominated throughout its evolution and excess fluvial sediments pass through the estuary into the sea only if the rate of volume increase of the drowned river valley exceeds the volume of sediment supply are deep water environments formed under such conditions an estuary becomes a sediment sink and infills by deltaic progradation and lateral accretion as predicted by evolutionary models for microtidal estuaries bedrock valley geometry may exert an important control on this rate of volume increase independently of variations in the rate of relative sea level change if estuarine morphology is viewed as a function of the balance of wave tidal and fluvial processes the mgeni estuary may be defined as a river dominated estuary in which deltaic progradation at the coast is limited by high wave energy it is broadly representative of other river dominated estuaries along the natal coast and a conceptual regional depositional model is proposed refinement of a globally applicable model will require further comparative studies of river dominated estuaries in this and other settings but it is proposed that river dominated estuaries represent a distinct type of estuarine morphology

the geomorphological evolution of a saline coastal lagoon on the southeast coast of australia swan lake new south wales coastal lagoons and estuaries in southeastern australia mainly occupy lowstand incised valley systems that have been impounded by post glacial sea level rise most previous research has focused on larger estuarine and deltaic systems but the swan lake deposits record the geomorphic evolution of a small perched saline coastal lagoon that has remained in a youthful stage of estuary infilling with very slow progradation of the bayhead delta and slow accumulation of the central basin mud facies this can be attributed to the relatively small catchment that is covered with natural vegetation marine influences at the flood tide delta have been restricted by the perched nature of the lagoon and the high wave energy on the coast that rapidly closes the entrance with sand comparison with other similar lagoons along the nsw coast between sydney and batemans bay illustrates the general geomorphic evolution of saline coastal lagoons such lagoons are also very similar to small perched lagoons in south africa and to a lesser extent with those on the east coast of south america

radiocarbon in the northern indian ocean two decades after geosecs 1 the 14c measurements in the arabian sea and the bay of bengal during the late 1990s offer a way to assess the temporal changes in the inventories of bomb 14c and its penetration into the ocean in two decades since geosecs expeditions 1977 1978 the mean penetration depth of bomb radiocarbon during geosecs 1977 1978 was 270 m which increased by 40 to 381 m in 1994 1998 the small changes in bomb 14c inventories significant increase in the mean penetration depths and lowering of the surface 14c values in the northern indian ocean indicate the temporal variation of bomb 14c in two decades is mainly through downward transfer through mixing with deeper waters the observed bomb 14c inventory in the northern indian ocean agrees with numerical model simulated values except at the equatorial indian ocean the high bomb 14c inventory at the equator can be attributed to lateral advection of 14c enriched waters from the pacific ocean through the indonesian archipelago the air sea co2exchange rates in the northern indian ocean calculated from the bomb 14c inventories range from 7 mol m 2 yr 1 in the northern bay of bengal to 20 mol m 2 yr 1 in the equatorial indian ocean net sea air flux of co2 estimated for the northern indian ocean between 0 and 25 n is 104 30 tgc yr 1 the bay of bengal is a net sink of atmospheric co2 1 0 4 tgc yr 1 while the arabian sea is a source of co2 69 21 tgc 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

oceanic radiocarbon separation of the natural and bomb components an improved method has been developed for the separation of the natural and bomb components of the radiocarbon in the ocean the improvement involves the use of a very strong correlation between natural radiocarbon and dissolved silica this method is applied to radiocarbon measurements made on samples collected during the geochemical ocean sections study geosecs transient tracers in the ocean tto and south atlantic ventilation experiment save expeditions on the basis of this new separation we provide not only an estimate of the global inventory of bomb 14c at the time of the geosecs survey but also the distribution of bomb radiocarbon along four thermocline isopycnals in each ocean we also document the evolution of the bomb 14c inventory and penetration along thermocline isopycnals in the north atlantic ocean between the times of the geosecs 1972 1973 and tto 1980 1982 surveys and in the south atlantic ocean between the times of the geosecs 1973 and save 1987 1989 surveys in addition we show that the bomb tritium to bomb 14c ratio expressed in the tritium unit tu 81 units 100 for waters entering the thermocline of the northern hemisphere is about 9 times higher than for those entering the southern hemisphere thermocline this contrast offers long term potential as an indicator of inter hemispheric transport of upper ocean waters

holocene palaeoecology and formation of the shoalhaven river deltaic estuarine plains southeast australia the shoalhaven river is one of the largest rivers on the south coast of new south wales and the deltaic estuarine plains associated with its mouth represent a mature stage of infill of a barrier estuary the stratigraphy of sediments from more than 60 drillholes from the plains indicates that the area has infilled during the mid holocene as a result of input of marine sands associated with a sand barrier on the high energy coast and fluvial mud and sands from the shoalhaven river molluscan assemblages indicate that marine influence was initially widespread throughout the eastern and southern parts of the embayment and that most of the plains infilled under estuarine conditions prominent levees across the plains surface are interpreted to be part of a birdsfoot delta distributary complex and individual floodbasins accreted progressively as they were encapsulated by distributary extension these former tidal environments mean that there are extensive potential acid sulphate soil conditions beneath the

sequence stratigraphy of a coastal plain incised valley estuary lake calcasieu louisiana abstract the stratigraphic profile along a 100 km section of the lake calcasieu incised valley fill was reconstructed from 87 bridge borehole records at four sites along the tidal reaches of the calcasieu river an additional 18 boreholes aligned along the chenier plain near the estuary mouth and shallow seismic data collected along 160 km of track line within the lake calcasieu central basin valley incision occurred during the d18o stage 2 sea level lowstand when the paleo calcasieu river flowed across the inner continental shelf and incised into older fluvial terraces of the prairie formation the valley floor is 57 m deep beneath the modern chenier plain and rises to 30 m along the upper reaches of the modern estuary sea level rise commenced about 20 ka and has continued episodically throughout the holocene shoreline transgression has proceeded at varying rates in response to sea level rise and the incised valley is now occupied by a wave dominated estuary fringed by the chenier plain of western louisiana lowstand deposits are poorly preserved within the calcasieu incised valley deposits constituting the transgressive systems tract tst lie directly above the lower sequence boundary at the top of the prairie formation the tst shows greatest facies diversity and clearest separation of bounding surfaces toward the present seaward end of lake calcasieu here the tst comprises three parasequences that include fluvial bayhead delta and central basin estuarine deposits multiple flooding surfaces within the tst relate to the episodic style of sea level rise highstand infilling of the valley has been characterized by nearshore marine deposition and chenier plain progradation along the lower reaches of the modern calcasieu river the valley fill comprises transgressive central basin nd landward stepping bayhead delta facies overlain by the highstand bayhead delta complex this study documents the most recent phase of deposition within the compound fill of a coastal plain incised valley and demonstrates the potential importance of fluvial controls on facies within incised valley systems

decade time scale variability of ventilation in the north atlantic high precision measurements of bomb radiocarbon in banded corals the first high precision radiocarbon measurements for the upper ocean are presented for banded corals from two sites in the north atlantic ocean the striking dissimilarities between the post 1950 records at bermuda in the sargasso sea and the florida straits in the gulf stream illustrate the different mixing processes in the upper ocean at each site convective overturn associated with 18 degree water formation during late winter in the northern sargasso sea facilitates storage of considerable quantities of bomb radiocarbon at depth which accounts for the damping of the 14c signal at bermuda during the 1960s a multibox isopycnal mixing model is used to estimate the ventilation rate of the upper 700 m of the water column in the sargasso sea from 1950 to 1983 an inverse model is used that is the water mass renewal rate was calculated for the post bomb period in order to satisfy the bomb radiocarbon time history in the corals sea water radiocarbon measurements made during the geosecs 1972 1973 and transient tracers in the ocean 1980 1981 surveys are used to constrain the subsurface radiocarbon values calculated by the model results show that the rate of water mass renewal in the sargasso sea was high during 1963 1964 decreased during the late 1960s and remained low during most of the 1970s the 14c derived record of water mass renewal precedes by about 4 years that derived from isopycnal salinity in the sargasso sea jenkins 1982 illustrating that the coral 14c record is controlled to a large extent by changes in ocean circulation rather than by atmospheric exchange of co2

the north south tilt in the australian height datum is explained by the ocean s mean dynamic topography 1 using geodetic and oceanographic data we show that the apparent north south slope between the australian height datum ahd and the geoid is caused almost completely by the ocean s time mean dynamic topography mdt this is because the ahd was constrained to zero height at local mean sea level at multiple tide gauges around the australian continent using mdt models and corrected leveling data almost all of the apparent north south slope can be removed from the ahd an auxiliary observation is that a satellite only mdt model based on only around one year of goce data generates results commensurate with geodetic oceanographic and combined mdt models

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

the upper hawkesbury river new south wales australia a holocene example of an estuarine bayhead delta holocene deposits of the hawkesbury river estuary located immediately north of sydney on the new south wales coast record the complex interplay between sediment supply and relative sea level rise within a deeply incised bedrock confined valley system the present day hawkesbury river is interpreted as a wave dominated estuarine complex divisible into two broad facies zones i an outer marine dominated zone extending 6 km upstream from the estuary mouth that is characterized by a large subtidal sandy flood tidal delta ocean wave energy is partially dissipated by this flood tidal delta so that tidal level fluctuations are the predominant marine mechanism operating further landward ii a river dominated zone that is 103 km long and characterized by a well developed progradational bayhead delta that includes distributary channels levees and overbank deposits this reach of the hawkesbury river undergoes minor tidal level fluctuations and low fluvial runoff during baseflow conditions but experiences strong flood flows during major runoff events fluvial deposits of the hawkesbury river occur upstream of this zone the focus of this paper is the hawkesbury river bayhead delta history of deposition within this delta over the last c 12 ka is interpreted from six continuous cores located along the upper reaches of the hawkesbury river detailed sedimentological analysis of facies whole core x ray analysis of burrow traces and a chronostratigraphic framework derived from 10 c 14 dates reveal four stages of incised valley infilling in the study area 1 before 17 ka bp a 0 1 m thick deposit of coarse grained fluvial sand and silt was laid down under falling to lowstand sea level conditions 2 from 17 to 6 5 ka bp a 5 10 m thick deposit composed of fine grained fluvial sand and silt muddy bayhead delta and muddy central basin deposits developed as the incised valley was flooded during eustatic sea level rise 3 during early highstand between 6 5 and 3 ka bp a 3 8 m thick bed of interbedded muddy central basin deposits and sandy river flood deposits formed in association with maximum flooding and progradation of sandy distributary mouth bar deposits commenced 4 since 3 ka bp fluvial deposits have prograded toward the estuary mouth in distributary mouth bar interdistributary bay and bayhead delta plain environments to produce a 5 15 m thick progradational to aggradational bayhead delta deposit at the mouth of the hawkesbury estuary subaqueous fluvial sands interfinger with and overlie marine sands the hawkesbury river bayhead delta depositional succession provides an example of the potential for significant variation of facies within the estuarine to fluvial segment of incised valley systems

step like migration of early aftershocks following the 2007 mw 6 7 noto hanto earthquake japan seismic data reveal that the aftershock zone expands with time after a main shock event here we examine the aftershock sequence recorded during the first 32 days following the 2007 noto hanto earthquake japan by applying a matched filter technique to the data we detected about 10 times more events than those listed in the routinely constructed earthquake catalog the aftershock area expanded along the fault strike as a logarithmic function of time beginning immediately after the main shock aftershock expansion toward the sw was especially extensive and developed more rapidly than toward the ne interestingly the aftershock area expanded in a step like manner by the activation of a series of spatially clustered seismic bursts spatial correlation between the aftershock extension and the afterslip distribution suggests that the expansion of the aftershock area could be mainly driven by aseismic afterslip the aftershock area continues to expand even though 7 years have now passed since the main shock

tidal velocity asymmetries and bedload transport in shallow embayments abstract tidal circulation can cause a net transport of sediment when the tidal velocity is asymmetric about a zero mean flood or ebb dominant and the sediment transport rate is related nonlinearly to velocity the relationship between tidal elevation and velocity is elucidated here to permit determination from tide gauge data and sediment transport relations whether tidal asymmetry needs to be considered as a mechanism for net sediment transport in the embayment of interest a relationship between elevation and velocity in a shallow water nonlinear system is derived through the continuity equation and shown to be significantly different than the linear relation finite difference numerical solutions of the one dimensional shallow water nonlinear equations are compared to the continuity relation and are in agreement especially toward the landward end of the channel tide gauge data collected at the landward end of the embayment are most useful for predicting velocity asymmetries throughout a major portion of the embayment channel the ratio of flood to ebb bedload transport and its relation to an asymmetric tidal elevation has been determined for both the linear relation between elevation and velocity and the nonlinear relation results show that the ratio of flood to ebb bedload transport as calculated from the nonlinear relation between elevation and velocity is similar to the flood to ebb ratio calculated from the linear relation because of offsetting effects

long term drainage evolution in the shoalhaven catchment southeast highlands australia the long term evolution of streams in the shoalhaven catchment of southeast new south wales has been a contentious issue for decades several authors have suggested that the shoalhaven river was captured at the sharp eastward bend near tallong this has been used as evidence for the westward migration of the east australian divide in this area other workers however have argued that capture did not occur and that the location of the divide has been stable throughout the tertiary a vast sheet of sediments which spread across and infill a palaeovalley network cut into a broad undulating plain in the middle shoalhaven catchment provides a record of stream behaviour since at least the start of the tertiary this record shows that the shoalhaven river and many of its tributaries have maintained almost the same courses since at least the very early tertiary this provides strong evidence against the capture hypothesis the record further suggests that during the paleogene these streams were graded to a level within the southeast australian highlands their depths of incision thus cannot be used as evidence for the extent of uplift of the southeast australian highlands during this time

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

separating natural and bomb produced radiocarbon in the ocean the potential alkalinity method alkalinity method provides an estimate of surface ocean prebomb d 14 c concentrations predictions with the technique appear to be unbiased and have uncertainties which are less than previous techniques index terms 4860 oceanography biological and chemical radioactivity and radioisotopes 4894 oceanography biological and chemical instruments and techniques

the distribution of bomb radiocarbon in the ocean water column inventories are calculated for bomb radiocarbon at all the stations occupied during the geosecs and norpax expeditions and for the available tto stations the pattern of global inventories obtained in this way suggests that a sizable portion of the bomb radiocarbon that entered the antarctic the northern pacific and the tropical ocean has been transported to the adjacent temperate zones a strategy for utilizing these inventory anomalies as constraints on global ocean circulation models is presented essential to this strategy are the improvement of our knowledge of the pattern of wind speed over the ocean the establishment of the wind speed dependence of the rate of gas exchange between the atmosphere and sea and the continued mapping of the distribution of bomb produced radiocarbon in the sea

smooth or oscillating late holocene sea level curve evidence from cross regional statistical regressions of fixed biological indicators abstract what if any is the pattern of change of the late holocene sea level curve if a common pattern exists can it be better discerned in the non glaciated tectonically stable regions of the southern hemisphere and is sea level data more reliable from one type of marine sample than another to begin an investigation of these questions we present a review of regressing time elevation plots from the low to mid latitudes of the southern hemisphere based upon the differential between modern and past levels of various fixed biological indicators mainly calcareous tubeworms and corals stranded up to 2 m above present relative sea levels the sample sets come from our work in southeast australia and comparable work from north east australia the pacific islands and brazil we show that using evidence obtained from fixed intertidal tubeworm species there is no statistical exclusivity between the smooth and oscillating polynomials but corals are more problematic in situ tubeworm species with their reduced error bars in comparison to corals fulfil the condition of providing more robust results for statistical analysis regression curves based on these species point to cross regional similarities in the pattern of sea level movement of the last 6000 years across the lower latitudes of the southern hemisphere these statistical exercises while not able to yield definitive conclusions can highlight statistically equally likely alternative patterns of sea level movement which can then be tested by field evidence they can also give useful indications of the quality of sea level data obtained from different biological sources as in the difficulties in the use of corals compared to common intertidal tubeworm species

smooth or oscillating late holocene sea level curve evidence from the palaeo zoology of fixed biological indicators in east australia and beyond abstract the nature of late holocene sea level change has important palaeo environmental implications for the understanding of past and present coastal oceanic and climatic systems this study develops a fixed biological indicator fbi method based on tubeworm barnacle assemblages in order to construct a late holocene sea level curve for south east australia it also compares changes within and between mid latitude regions of the southern hemisphere using the palaeo biology of inter tidal sub fossils that have provided time elevation data covering the past 5000 years five sites from around the mouth of the port hacking estuary 29 km south of sydney are described in detail the results suggest that rather than relative sea level describing a stable or smoothly falling pattern from a maximum of 1 0 m above present over the last 5000 years on the southeast australian coast there have been complex movements from a maximum of over 1 5 m with at least one marked fall between 3500 and 3400 yr bp and the possibility of a small positive oscillation around 1900 yr bp furthermore changes in the inter tidal species at our sites suggest that there was a period between 4300 and 2800 years where ocean temperatures were warmer than present our port hacking findings are compared with other studies from the east coast of australia as well as the pacific islands and brazil evidence from each location suggests a broad similarity in the timing of environmental events and marine fluctuations across an expanse of the southern hemisphere are such similarities coincidental or part of mechanisms common to mid latitude southern hemisphere regions

ordovician contourites in the lachlan fold belt eastern australia abstract the ordovician sequence in the northeastern lachlan fold belt consists of three lithologic units representing an overall fining upward succession from turbidites to black shale the lowest unit dominated by turbidite beds represents a small segment of an extensive ordovician submarine fan sequence that covered much of southeastern australia the overlying unit consists predominantly of ripple bedded sandstone with beds 3 5 cm thick these beds are texturally mature containing heavy minerals mica and silt concentrated on the cross laminae the ripple bedded unit has a mean palaeocurrent trend to 321 which is at 60 to sole marks and almost normal to the trend of ripple cross bedding in the underlying and associated turbidite beds this unit is here interpreted as a sandy contourite sequence that can be attributed to contour currents moving northwards along the eastern margin of gondwana from areas of subpolar downwelling off southern africa and america the two major fining upward successions in the ordovician sequence in southeastern australia may reflect eustatic sea level rises during the middle and late ordovician and thus provide evidence of interglacial periods in the darrawilian and late gisbornian to bolindian the contourites would have accumulated in the latter stages of the glacial periods after sea level had risen sufficiently to cut off major sediment supply to the submarine fan but before the temperature had risen to the extent of preventing deep thermohaline circulation

bomb radiocarbon in the red sea a medium scale gas exchange experiment the history of bomb produced radiocarbon in the surface waters of the red sea and the western gulf of aden was reconstructed from annual growth bands of corals gulf of aden surface water entering the red sea and flowing to the north at the surface of the red sea becomes progressively enriched in bomb sup 14 c by air sea exchange of carbon dioxide with physical oceanographic observations and analysis as the basis of a simple model this progressive northward enrichment can be used to calculate a mean invasionn flux for co sub 2 across the red sea surface the co sub 2 invasion flux so calculated is 8 mol m sup 2 yr with an uncertainty of approximately 2 mol m sup 2 yr when combined with the extensive historical observations of wind speeds in the red sea the calculated co sub 2 invasion flux supports the empirical relationship between co sub 2 invasion and wind speed proposed by other workers sea surface pco sub 2 was measured at seven stations along the length of the red sea in january 1985 these pco sub 2 data show that in midwinter the net flux of co sub 2 across the red sea surface i e the difference between the invasion and evasion fluxes is approximately zero formore the red sea as a whole copyright american geophysical union 1989 less

intermittently closed open lakes and lagoons their global distribution and boundary conditions abstract intermittently closed open lakes and lagoons icolls are a particularly dynamic form of estuary characterised by periodic entrance closure to the ocean closure occurs when a subaerial sand berm stabilises across the entrance channel during times of low fluvial discharge icolls are of global importance as they provide valuable ecological habitats for many species and are associated with a wide range of management issues due to their cycle of entrance closure and opening icolls are found to be more widespread globally than previously described with 1477 of these estuaries being identified in this study this constitutes an estimated 3 of the world s estuaries and 15 of all estuaries along microtidal coastlines icolls are concentrated along microtidal to low mesotidal coastlines in the mid latitudes and predominantly on coasts with temperate climates this distribution is related to greater wave heights as driven by high intensity winds and a longer fetch distance the highest proportion of icolls are present in australia 21 all global icolls south africa 16 and mexico 16 in australia a comparison with fluvial input found that it is less important than marine processes in determining icoll formation and that icolls are associated with a relative tidal range of