cambrian shoreline deposits in northern michigan abstract shoreline deposits have been recognized rarely in pure quartz arenites that were deposited before the advent of land vegetation the late cambrian munising formation of northern michigan is an exception both conglomerate and shale are relatively more common here than in most similar cratonic sandstones apparently because of an important fluvial influence a basal conglomerate member is interpreted as a low sinuosity braided fluvial deposit the overlying chapel rock member has unfossiliferous large scale cross bedded sandstones with minor but widespread conglomerate interpreted as braided fan delta distributary deposits and associated horizontally stratified sandstone with wave ripples polygonally cracked shales and trace fossils interpreted as interdistributary deposits both of these latter facies are punctuated by unsorted unstratified channelized conglomerate and intraclast breccia which are interpreted as river flood avulsion deposits although fluvially dominated the depositional system also had wave and probable tidal influences as well as local eolian reworking of fluvial sands thus a shoreline setting adjacent to highlands centered over the northern michigan wisconsin border is indicated the overlying miners castle member is interpreted as transgressive marine deposits formed as nearby highlands became mostly submerged the lower strata are sandstones with medium scale trough cross bedding thin flaser like shale drapes accumulated along many cross laminae and over rippled beds these are interpreted as prodeltaic the upper strata have little shale but much bioturbation and some skeletal fossils and are interpreted as more distal shelf deposits the rather unusual association in the munising formation of conglomerate and shale with cross bedded quartz arenite the particular distribution of trace and skeletal fossils and of mud crocks and wave ripples allow an environmental reconstruction that may provide valuable analogies for other hitherto unrecognized pre vegetation shoreline deposits

an oligocene palynoflora from the middle shoalhaven catchment n s w and the tertiary evolution of flora and climate in the southeast australian highlands abstract well preserved spores and pollen from a number of middle oligocene sedimentary formations in the middle shoalhaven catchment n s w are correlated with the upper nothofagidites asperus lower proteacidites tuberculatus zones of the gippsland basin victoria further confirmation of this correlation comes from three sources a the relative abundances of pollen component groups reveal the nothofagidites proteacidites and myrtaceidites groups within the shoalhaven assemblage to be typical of late eocene to middle oligocene sequences b comparisons with the ratios of phyllocladidites mawsonii to gymnosperms araucariacites to gymnosperms n flemingii to other nothofagidites and myrtaceae to nothofagidites in the murray basin indicate at least an upper n asperus age and c strong geomorphic and stratigraphic evidence reported elsewhere shows that the spore and pollen bearing sediments were deposited in a basalt dammed lake between 29 32 ma the mid oligocene shoalhaven assemblage fills a significant gap in the spore pollen record of the southeast australian highlands and as a consequence there is now a continuous record of development of flora and climate for this region for nearly the entire tertiary average annual temperature and thermal seasonality appear to have been the two most significant climatic parameters to have varied throughout the southeastern highlands from the palaeocene to the miocene after which progressively drier conditions ensued

trace fossils and substrates of the terminal proterozoic cambrian transition implications for the record of early bilaterians and sediment mixing the trace fossil record is important in determining the timing of the appearance of bilaterian animals a conservative estimate puts this time at 555 million years ago the preservational potential of traces made close to the sediment water interface is crucial to detecting early benthic activity our studies on earliest cambrian sediments suggest that shallow tiers were preserved to a greater extent than typical for most of the phanerozoic which can be attributed both directly and indirectly to the low levels of sediment mixing the low levels of sediment mixing meant that thin event beds were preserved the shallow depth of sediment mixing also meant that muddy sediments were firm close to the sediment water interface increasing the likelihood of recording shallow tier trace fossils in muddy sediments overall trace fossils can provide a sound record of the onset of bilaterian benthic activity

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

late wisconsinan stratigraphy and chronology of southern st george s bay newfoundland a re appraisal reply brookes identifies two points of difference in his discussion of our re appraisal of the late wisconsinan stratigraphy and chronology of southern st george s bay newfoundland i the applicability of our sedimentological model and ii the relation of sediments to late glacial sea level the latter point is the subject of a manuscript submitted for review to this journal incorporating 91 radiocarbon dates from onshore and offshore marine records 19 of which are reported for the first time we therefore restrict our rebuttal to what we believe are the critical disagreements in field observations and interpretations that underpin the two points of difference and invite readers to visit the contentious coastal sections to compare published accounts access to these sites is described in several field guides to southern st george s bay liverman and batterson 1995 liverman et al 2001 in our paper we explicitly state that for 80 of the 39 km long coastal exposure our non ridge sections p 866 our observations broadly confirm earlier interpretations by brookes 1969 1974 1977 and macclintock and twenhofel 1940 with the one important exception that we found no evidence for glacial readvance following initial deglaciation and marine submergence of the present coastline in almost 100 logged sections through non ridge exposures we did not encounter an upper till or ice contact gravels robinsons head drift indicative of a glacial readvance instead we described laterally continuous moderately to well sorted planar bedded and trough cross bedded fine gravel capping sections which we interpreted as glaciofluvial outwash p 859 figs 4 5 c consequently our deglacial depositional model for a large part of the coast of southern st george s bay is neither compatible with nor applicable to published sedimentary sequences in the remaining 20 of coastal exposure our ridge sections p 866 our mapping revealed complex sedimentary sequences of interbedded diamicton gravel and mud above

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

late wisconsinan stratigraphy and chronology of southern st george s bay newfoundland a re appraisal discussion a sedimentological model has been presented by bell et al 2001 to explain the stratigraphy and chronology of glacigenic sediments at localities in southern st george s bay west newfoundland these authors claim that this model succeeds earlier interpretations of the sediments at these localities made by macclintock and twenhofel 1940 and brookes 1969 1974 1977 a and by implication find fault with the history of late glacial relative sea level for these localities and the wider area presented in brookes 1974 1977 a and with some revision in forbes et al 1993 this note draws attention to two points of difference i have with bell et al 2001 at the local and regional scales namely the applicability of the adopted sedimentological model and the relation of the sediments concerned to late glacial sea level macclintock and twenhofel 1940 presented an inventory and interpretation of glacial and associated sediments exposed in tens of kilometres of coastal cliffs around st george s bay well portrayed in bell et al 2001 fig 4 they divided the sediments into i a compact basal till low in the cliffs overlain in places by kame gravels named st george s river drift ii an overlying marine sequence comprising lower muds and higher deltaic sands and gravels in places underlying a delta surface named bay st george delta and iii in a few places an upper unit of till and kame gravel with morainic topography named robinsons head drift the sequence was interpreted to have resulted from an ice advance beyond the present coast of the bay followed by ice retreat and local stagnation at the present coast then by marine submergence and finally an ice readvance in several lobes across the present coastline into the sea and sediments previously deposited in it brookes 1969 1974 1977

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

early tertiary palaeogeography landform evolution and palaeoclimates of the southern monaro n s w australia the age of the southern highlands of australia has long been controversial recent field investigations around bombala in southern new south wales have shed some light on this as well as on the early tertiary palaeoclimates in southern australia late palaeocene basalts were extruded on a landscape with a relief of at least 400 m and possibly as much as 800 m showing that the region had a substantial relief by the beginning of the tertiary fluvial and lacustrine sediments deposited on the earlier or prebasaltic landscape have been preserved by the basalt and contain palynofloras and fossil wood as do sediments deposited between basalt flows in the lower parts of the basalt pile the palynomorphs are representative of the lygistepollenites balmei zone in the upper late paleocene ca 58 60 ma the pollen and fossil wood indicate the region was covered by cool temperate rainforest podocarps and araucarian conifers were significant components of these forests in addition to nothofagus ferns were prominent in some localities the fossil wood is dominated by gymnosperms comparison of the palynofloras with bioclimatic data of a number of descendant extant species has shown that most belong to the mesotherm response category with mean annual temperatures in the range 14 20 c there is little evidence that frosts were significant data from tree rings support this and show that climates were markedly seasonal the annual rings are very thin suggesting cool climates their uniformity shows that conditions varied little from year to year

wrinkle structures microbially mediated sedimentary structures common in subtidal siliciclastic settings at the proterozoic phanerozoic transition sedimentary structures produced by microbial activity are well known from ancient carbonate facies but little is known about equivalent microbial structures in ancient siliciclastic facies wrinkle marks and kinneyia ripples are closely related sedimentary structures that are commonly found in ancient siliciclastics and they may represent microbial activity to evaluate this possibility these structures were studied in vendian cambrian strata of north america and compared to structures formed by modern microbial mat communities in redfish bay texas striking similarities in sedimentologic petrographic and morphologic characteristics of modern and ancient occurrences suggest that the enigmatic but widespread ancient structures could have been formed by microbial processes the relative abundance of these structures in siliciclastic facies of this interval further suggests that prior to the onset of relatively intense bioturbation in the ordovician microbial mats could have played a significant role in the evolution and diversification of early life in a broad variety of sea floor environments

evidence for smoothly falling sea level relative to north queensland australia during the past 6 000 yr post glacial sea level curves are expected to differ between different parts of the world as a result of global isostatic changes1 or perhaps other forms of geoidal changes2 i report here results from the inner part of the northern great barrier reef which seem to show a pattern of smoothly falling sea level during the past 6 000 yr the results are consistent with stratigraphical results from prograded mangrove coasts on the nearby north queensland mainland the region is remote from the tectonically active margin of the south west pacific ocean and the results contribute to the global data set relevant to isostatic changes being assembled by the international sea level project igcp project no 61 they also provide a baseline relevant to holocene coral reef growth in the inner great barrier reef

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

late pleistocene and holocene sea level change along the australian coast abstract tectonically the australian continent is relatively stable and as such it provides a good platform for studying late pleistocene and holocene sea level change the observations indicate that present sea level was reached at about 6000 years ago and that since then level has remained constant to within a few metres considerable spatial variability in the amplitude of the emergence and in the time at which sea levels first reached their present values have been observed spatial variability has also been observed in the sea level during the last glacial maximum and during the late phase of the holocene transgression much of this variaiblity is the result of the earth s adjustment to the glacial melting in the late pleistocene early holocene time and the concomitant distribution of this meltwater into the oceans conclusions that are drawn from matching observations with this glacio hydro isostatic model include the following 1 the mantle viscosity increases with depth the average upper mantle viscosity is about 2 3 10 20 pa s and the average lower mantle defined as below 670 km depth viscosity is about 10 22 pa s the average lithospheric thickness for the coastal and offshore region is about 70 80 km lateral variations in these mantle parameters are indicated 2 the addition of melwater into the oceans did not cease 6000 years ago but continued at a reduced rate up to more recent times adding an amount of water equivalent to a 3 m sea level rise in this interval 3 the amplitude of the holocene emergence is a function inter alia of coastal geometry and significant variations occur over distances of a few hundred kilometres and more holocene highstands of 1 2 m are generally well developed at the continental margins but are less well developed or do not developed at all at offshore islands and reefs 4 variations in the time of maximum emergence also occur being earlier at upstream tidal river sites than at coastal sites at offshore reefs or islands the sea level curve lags the coastal curves by 1000 years or more 5 considerable spatial variability occurs in the sea levels at the time of the last glacial maximum with variations of up to 30 m occurring across the continental shelves 6 there is generally no need to invoke tectonic movements to explain the sea level data along the australian coast but possible exceptions occur for the perth region and for tasmania

ironstones and green marine clays in the dongjeom formation early ordovician of korea abstract in the sino korean north china block the occurrence of ironstone is reported for the first time from the lower ordovician dongjeom formation korea the dongjeom formation comprises much quartzose sediment deposited on the extensive carbonate platform and is composed of three coarsening upward sequences ironstone beds are distributed on the tops of the lower two sequences suggesting that they mark approximately maximum flooding events during the relative lowstand of sea level when the dongjeom formation was deposited extensive weathering in the source areas coupled with higher order sea level rises resulted in the formation of the dongjeom ironstones the dongjeom ironstones include much green marine clays ironstones of the lowest sequence are characterized by glaucony facies and those of the middle sequence by chamosite facies chemical compositions of dongjeom glauconies reveal that they were originally nascent to slightly evolved 3 to 5 k 2 o wt and that they were affected by illitization after burial their immature compositions suggest that glauconies were formed in about 10 3 to 10 4 years or less on the seafloor the substrates for glauconitization are interpreted as detrital mineral grains regressions after glauconitization introduced iron oxides to the green grains eventually forming the iron oxide rich band under the most oxidizing conditions the distribution of glauconies in limited horizons suggests that the dongjeom glauconies are autochthonous in origin chamosites have granular shapes and are mixed with quartzose sand grains suggestive of reworking during storms the dongjeom chamosites were transformed from the precursor berthierines the occurrence of glauconies in correlative horizons in korea and north china may indicate that glauconitization in the host sediments which were deposited in far northern gondwana occurred under the influence of a coeval transgressive event

holocene sea level change and coastal landscape evolution in the southern gulf of carpentaria australia a revised holocene sea level history for the southern gulf of carpentaria is presented based on new data from the south wellesley archipelago and age recalibration of previous research results confirm that rising sea levels during the most recent post glacial marine transgression breached the arafura sill ca 11 700 cal yr bp sea levels continued to rise to ca 30 m by 10 000 cal yr bp leading to full marine conditions by 7700 cal yr bp sea level reached present mean sea level pmsl and continued to rise to an elevation of between 1 5 m and 2 m above pmsl sea level remained ca 1 5 between 7000 and 4000 cal yr bp followed by rapid regression to within 0 5 m of pmsl by ca 3500 cal yr bp when placed into a wider regional context results from this study show that coastal landscape evolution in the tropical north of australia was not only dependent on sea level change but also show a direct correlation with holocene climate variability specifically the formation and preservation of beach rock deposits intertidal successions beach and chenier ridge systems hold valuable sea level and holocene climate proxies that can contribute to the growing research into lower latitude holocene sea level and climate histories

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

early cambrian teichichnus dominated ichnofabrics and palaeoenvironmental analysis of the caerfai group southwest wales uk abstract the early cambrian caerfai group of pembrokeshire in southwest wales yields an intensely bioturbated teichichnus dominated ichnofabric and provides evidence for the early evolution of infaunal organisms three units of the caerfai group comprise the focus of this study in sections exposed at caerfai bay in the st non s sandstone few primary sedimentary structures are observed bedding being predominantly massive with subordinate parallel and current ripple cross lamination the topmost st non s sandstone contains common soft sediment deformation phenomena and collectively deposition is believed to have taken place in the proximal subaqueous reaches of a steep fronted delta system teichichnus is the dominant trace with subordinate planolites palaeophycus and possible rhizocorallium the overlying caerfai bay shales were deposited from mass flows with evidence of downslope creep suggesting deposition on a steep delta front sandstone debrites are common as are tuffaceous beds with evidence of reworking by bottom currents sandstone and tuff event beds contain common skolithos and arenicolites with less frequent planolites interbedded mudstones contain infrequent teichichnus the caerfai bay shales coarsen and thicken upwards into the caerbwdy sandstone debrite sandstone beds dominate and bed thickening upsection indicates progradation of the delta system the dominant trace fossil within the unit is teichichnus which is constrained to the top few centimetres of individual sandstone beds less common are planolites and palaeophycus the size and abundance of teichichnus in the caerfai group are similar to or exceed those in contemporaneous sections in avalonia and baltica local environmental factors were probably the primary control on trace fossil distribution substrate and salinity are proposed as the main influences on ichnodiversity and size in the caerfai group teichichnus is most abundant in the st non s sandstone where the proximal reaches of the delta experienced reduced salinity and possibly higher oxygen levels burrow diameter progressively decreases upsection and bioturbation becomes less pervasive in subsequent units of the caerfai group this indicates that by the cambrian stage 2 significant advances into reduced salinity environments had occurred along with the dispersal of the teichichnus producer throughout the avalonia baltica seaway correlation within avalonia indicates that a transgression in the cambrian stage 2 initiated the deposition of the caerfai group marking the onset of the welsh basin

predicted and observed holocene sea levels on the australian coast what do they indicate about hydro isostatic models in far field sites data relating to holocene sea level elevations and ages obtained by radiocarbon dating of relict calcareous skeletons of intertidal organisms from widely spaced parts of the australian coast a far field region of comparative tectonic stability are divisible into two sets namely pre and post ca 3600 yr bp the older ages are from material consistently between 1 5 m and 2 2 m higher than present sea level whereas the younger ages ca 3600 1500 yr bp generally cluster around 1 m above present sea level the elevations do not display any decline in amplitude from north to south over an extensive transect contrary to predictions by hydro isostatic models also there appears to be little difference between time elevation results for the coasts of north queensland new south wales and the bass strait region adjacent to tasmania despite differences in the width of the continental shelf in these three locations and the expectation of some hydro isostatic warping of the continental shelf subsequent to the onset of the holocene transgression results from the south and southwest coasts of western australia also display similar elevations to the east coast for the same time periods there is sufficient evidence extending over 20 of latitude to suggest that north south differences related to hydro isostatic influence is limited or non existent there is insufficient data to test hydro isostatic models across continental shelves hydro isostasy and the lithological elasticity it reflects may not be as pronounced in far field sites with narrow continental shelves as models predict stable far field passive continental margins may be the best place to measure the ratio of inputs of eustatic and hydro isostatic influences on holocene relative sea levels copyright 2002 john wiley sons ltd journal of quaternary science

warmer or cooler late holocene marine palaeoenvironments interpreting southeast australian and brazilian sea level changes using fixed biological indicators and their δ18o composition abstract relic inter tidal assemblages of sessile organisms which are referred to as fixed biological indicators fbis are shown to be useful proxies for late holocene climatic and environmental changes as well as direct indicators of short term fluctuations in sea level a detailed comparison of change in the inter tidal assemblages of two southern hemisphere sites at comparable latitudes port hacking new south wales south east australia and the laguna imbituba region of southern brazil indicates periods of marked similarities in the timing and nature of changes at 5200 3800 cal years bp and differences after 2400 cal years bp there is sufficient concurrence of cooling phases and falling sea levels to strongly suggest that in some cases global rather than regional forcing factors are at work the value of inter tidal organisms as indicators of changed environments is developed by identifying the past and present distributions of the common marker species tubeworms barnacles and mussels the 18 o content of these extant specimens at port hacking confirmed changes in ocean water temperature and associated sea level behaviour corresponding to invasion or extinction of temperature sensitive species a similar pattern is repeated although in a less marked fashion in the laguna imbituba region of southern brazil

the ichnogenus rhizocorallium classification trace makers palaeoenvironments and evolution rhizocorallium is one of the oldest known trace fossils with wide distribution through the phanerozoic and all over the world originally introduced from the epicontinental triassic of central germany its high morphological lability gave reason for the subsequent erection of about twenty ichnospecies the study of newly collected material from the type area and many specimens from various collections permits the conclusion that rhizocorallium jenense and rhizocorallium commune are the only valid ichnospecies of rhizocorallium the type ichnospecies r jenense is a comparatively small inclined and heavily scratched firmground burrow with passive fill while r commune consists of extensive more or less horizontal burrows with occasionally scratched marginal tubes and an actively filled spreite between the tubes the faecal pellets coprulus oblongus are typically associated with r commune morphological variations of r commune are captured in ichnosubspecies and varieties of this ichnospecies and can aid a refined reconstruction of palaeoenvironments a review of more than 180 records from the literature reveals the common confusion of both ichnospecies which has consequences for the application of rhizocorallium in facies interpretations the end members of both ichnospecies may be linked by transitional forms which suggests the same kind of trace maker polychaetes are the most likely producers of marine rhizocorallium based on their long ranging occurrence morphological features appearance of faecal pellets associated soft body remains and modern analogues r commune occurs from early cambrian to holocene while r jenense just appears after the end permian mass extinction probably as a consequence of an adapted firmground burrowing lifestyle of its producer fluvial r jenense are probably produced by mayfly larvae in homology to marine polychaete burrows a consequent application of the newly established classification scheme allows for a more rigorous application of rhizocorallium in the reconstruction of palaeoenvironments thus palaeozoic and mesozoic r commune are restricted to the cruziana ichnofacies of shallow marine environments while in cenozoic time similar forms are also found in deep marine deposits r jenense on the other hand is a constituent of the widespread glossifungites ichnofacies and aside from continental environments occurs in peritidal to deep marine deposits several studies have demonstrated the value of rhizocorallium for interpreting sequence stratigraphical surfaces current directions and fluctuations in salinity and oxygen

exploring the aftermath of the cambrian explosion the evolutionary significance of marginal to shallow marine ichnofaunas of jordan the middle cambrian hanneh member of the burj formation and the middle to upper cambrian umm ishrin formation of the dead sea area jordan contain well preserved and abundant ichnofaunas trace fossils are present in a wide variety of depositional environments from tide dominated shelf to prodelta delta front and interdistributary bay tidal flats twelve trace fossil assemblages have been identified within a number of sequence stratigraphic settings namely early transgressive subtidal dune and bar complex late transgressive isolated dune patches and dune field abandonment highstand deltaic progradation and forced regressive deltaic progradation these ichnofaunas provide information that helps us to understand the nature of cambrian ecosystems in the aftermath of the cambrian radiation the jordan ichnofaunas display evidence of firm ground conditions at or near the sea bottom these include 1 well preserved scratch marks in most cruziana and rusophycus ichnospecies 2 adhering gyrolithes polonicus burrows and 3 unlined passively filled diplocraterion isp penetrating into underlying mudstone whereas the diplocraterion isp occurrences are a classic example of the glossifungites ichnofacies linked to erosional exhumation the firmground g polonicus is associated to a maximum flooding surface with no erosion involved the trace fossil suites dominated by trilobite structures are firmground examples of the cruziana ichnofacies raising issues with respect to the substrate affinities of this ichnofacies which is typically considered indicative of softgrounds our study underscores evolutionary controls on this ichnofacies suggesting that lower paleozoic occurrences which are dominated by trilobite trails and trackways reflect firm substrates and younger ones represent the typical softground examples the occurrence of abundant bilobate trace fossils scratch marks and trackways in interdistributary bay tidal flats within a braidplain delta complex in the umm ishrin formation provides evidence that arthropods were able to foray into marginal marine brackish water settings during the cambrian analysis of the tiering structure indicates relatively simple communities and limited use of the infaunal ecospace low energy fully marine and marginal marine ichnofabrics are dominated by shallow tier deposit and detritus feeding trace fossils deep tier structures of detritus feeders are present in ichnofabrics from fully marine low energy settings whereas deep tier trace fossils of suspension feeders are dominant in high energy subtidal zones

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

stream response to quaternary climate change evidence from the shoalhaven river catchment southeastern highlands temperate australia abstract luminescence ages from a flight of four paired alluvial terraces in the upper catchment of the shoalhaven river southeast highlands australia provide a record of stream behaviour throughout the late quaternary ages ranging from 7 ka in the modern floodplain to nearly 500 ka for the uppermost dated terrace allow comparisons to be made of the response of streams throughout southeastern australian to late quaternary climatic perturbations the alluvial record of the shoalhaven river highlights the broad regional synchronicity of episodes of heightened fluvial activity during oxygen isotope stage ois 5 terminating 75 ka 60 40 30 25 and 20 15 ka the shoalhaven record also shows an absence of fluvial activity during the last glacial maximum suggesting that southeastern australia was most likely dry at this time as compared to northern australia which was probably wet fluvial activity while still significant decreased substantially after approximately 60 ka suggesting a general drying of climate towards the present

controls on post mid cretaceous landscape evolution in the southeastern highlands of australia insights from numerical surface process models the tectonic and geomorphic evolution of the southeastern australian highlands has been a subject of controversy among geophysicists geologists and geomorphologists for several decades we employ a numerical surface process model that includes long range fluvial transport hillslope diffusion and landsliding in order to quantitatively assess the tectonic lithological and structural controls on the landscape evolution and denudation history of se australia we constrain fluvial erosion parameters for our model by fitting river profiles rockfall and landsliding are the most important processes controlling the concentration of erosion in river valleys we therefore model hillslope evolution using a very low diffusion coefficient and a threshold slope for landsliding the initial prebreakup topography of the highlands provides a fundamental control on their subsequent evolution together with the style and rate of fluvial incision secondary controls are exerted by lateral variations in lithology and local tectonic uplift along faults our modeling results indicate that 1 the observed highlands morphology requires that the drainage divide was established at its present location prior to opening of the tasman sea whether the divide is inherited from paleozoic orogeny or resulted from mesozoic syn rift uplift cannot be established however 2 in contrast to traditional interpretations escarpment retreat does not appear to be the fundamental process eroding the highlands and 3 the observed barbed river drainage may be imprinted as a result of lithological variation it does not necessarily evolve through capture the driving mechanism that is most consistent with the inferred uplift pattern of the southeastern highlands appears to be magmatic underplating

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

stability and facies association of early diagenetic mineral assemblages an example from a jurassic ironstone mudstone succession u k abstract sedimentological and petrographic data from two lower liassic ooidal ironstones the frodingham and pecten ironstones and associated mudstones from eastern england have been collected within these ironstones early diagenetic berthierine siderite and minor glauconite have a limited lateral extent associated with an intrabasinal high the market weighton swell this mineral assemblage passes laterally and vertically into mudstones and silty mudstones within which pyrite is the dominant early diagenetic iron mineral the ironstones are stratigraphically condensed having experienced low net sediment accumulation rates and shallow high energy conditions thermodynamic considerations indicate that berthierine and siderite should be stable in anoxic environments where sulfide activity is negligible pyrite is rare within the ironstones suggesting that sulfate reduction was a negligible process during ironstone formation where pyrite is present it postdates berthierine and siderite indicating that sulfate reduction may have been a later process in some beds we propose that berthierine and siderite were precipitated during suboxic diagenesis where sulfate reduction was inhibited and iron reduction was the dominant process of organic matter oxidation suboxic diagenesis resulted from the extended periods of physical and biological sediment reworking during ironstone deposition which favored the oxidation of iron minerals and aerobic egradation and loss of organic matter berthierine formed during early suboxic diagenesis at the expense of detrital clays and iron oxides during later suboxic diagenesis pore water bicarbonate activities increased leading to siderite precipitation early glauconite also formed in places and it seems likely that it formed close to the oxic suboxic interface the predominance of pyrite in the mudstones indicates that sulfate reduction was the major process of organic matter oxidation during early diagenesis

late holocene higher sea level indicators from eastern australia abstract new age data from intertidal organisms exposed on coastal cliffs in northern new south wales suggest that in that area sea level was slightly more than 1 m higher about 3420 yrs b p and may have fallen to its present level since 1780 yrs b p these findings if regionally significant are important because they indicate that the tidally constructed zonations of organisms on high energy rocky coast could provide a more precise record of sea level behaviour than the study of constructional geomorphic features often related to storm events such as beach ridges chenier plains tidal deltas etc or mangrove peats

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

soil production on a retreating escarpment in southeastern australia the functional dependence of bedrock conversion to soil on the overlying soil depth the soil production function has been widely recognized as essential to understanding landscape evolution but was quantified only recently here we report soil production rates for the first time at the base of a retreating escarpment on the soil mantled hilly slopes in the upper bega valley southeastern australia concentrations of 10 be and 26 al in bedrock from the base of the soil column show that soil production rates decline exponentially with increasing soil depth these data define a soil production function with a maximum soil production rate of 53 m m y under no soil mantle and a minimum of 7 m m y under 100 cm of soil thus constraining landscape evolution rates subsequent to escarpment retreat the form of this function is supported by an inverse linear relationship between topographic curvature and soil depth that also suggests that simple creep does not adequately characterize the hillslope processes spatial variation of soil production shows a landscape out of dynamic equilibrium possibly in response to the propagation of the escarpment through the field area within the past few million years in addition we present a method that tests the assumption of locally constant soil depth and lowering rates using concentrations of 10 be and 26 al on the surfaces of emergent tors

fluvial archives a valuable record of vertical crustal deformation abstract the study of drainage network response to uplift is important not only for understanding river system dynamics and associated channel properties and fluvial landforms but also for identifying the nature of crustal deformation and its history in recent decades geomorphic analysis of rivers has proved powerful in elucidating the tectonic evolution of actively uplifting and eroding orogens here we review the main recent developments that have improved and expanded qualitative and quantitative information about vertical tectonic motions the effects of horizontal deformation are not addressed channel long profiles have received considerable attention in the literature and we briefly introduce basic aspects of the behaviour of bedrock rivers from field and numerical modelling perspectives before describing the various metrics that have been proposed to identify the information on crustal deformation contained within their steady state characteristics then we review the literature dealing with the transient response of rivers to tectonic perturbation through the production of knickpoints propagating through the drainage network inverse modelling of river profiles for uplift in time and space is also shown to be very effective in reconstructing regional tectonic histories finally we present a synthetic morphometric approach for deducing the tectonic record of fluvial landscapes as well as the erosional imprint of tectonic forcing sedimentary deposits such as fluvial terrace staircases are also considered as a classical component of tectonic geomorphology we show that these studies have recently benefited from rapid advances in dating techniques allowing more reliable reconstruction of incision histories and estimation of incision rates the combination of progress in the understanding of transient river profiles and larger more rigorous data sets of terrace ages has led to improved understanding of river erosion and the implications for terrace profile correlation i e extrapolation of local data to entire profiles finally planform changes in fluvial systems are considered at the channel scale in alluvial rivers and regional level in terms of drainage reorganisation examples are given of how numerical modelling can efficiently combine with topographic data to shed new light on the dis equilibrium state of drainage systems across regional drainage divides

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

late quaternary erosion in southeastern australia a field example using cosmogenic nuclides late quaternary rates of apparent soil production bedrock incision and average erosion are determined for the southeastern highlands of australia using in situ produced cosmogenic nuclide concentrations of 10 be and 26 al apparent soil production rates define a steep inverse exponential function of soil depth with a maximum of 143 m ma 1 under zero soil depth there were no observed soil depths between about 25 cm and zero however such that the maximum observed rate is about 50 m ma 1 the bredbo river catchment average erosion rate is 157 1mm a 1 and is similar to the average hillslope erosion rate of 167 1mm a 1 bedrock incision rates average 9 mma 1 and suggest that the higher rates of hillslope erosion may be in response to a pulse of incision perhaps generated by knickpoint propagation bedrock erosion rates inferred froma tor profile average 3 8 mma 1 with higher rates on other more weathered tor tops an aboveground tor profile of nuclide concentrations is consistent with a simple model of rapid stripping of the surrounding saprolite supporting the view that at least one episodic period of increased denudation has affected the landscape evolution of the highlands we test this hypothesis by using a simple landscape evolution model to reasonably predict the spatial variation of soil depth as well as the emergence of tors r 2001 elsevier science ltd and inqua all rights reserved

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

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

the onset of the ordovician plankton revolution in the late cambrian abstract the great ordovician biodiversification event comprises the rapid diversification of marine organisms during the ordovician period it is now clear that this adaptive radiation started for some organisms already in the cambrian and continued for others beyond the end of the ordovician making the great ordovician biodiversification event part of a long term late proterozoic and early palaeozoic radiation that in part is expressed by the fossil record as the cambrian explosion a significant diversification of different groups of the plankton is observed in the late cambrian early ordovician interval leading to the subsequent ordovician plankton revolution the possible causes of this plankton revolution are currently debated they include changes in palaeoclimate palaeogeography or tectonic and volcanic activity as well as a modified nutrient supply in this context the steptoean positive carbon isotope excursion 13 c carb spice event in the late cambrian paibian stage furongian series has been related to a major increase in atmospheric o 2 from 10 18 to some 20 29 and to increased oceanic nutrient availability here we analyze the diversification of the planktonic groups during the late cambrian and early ordovician in particular in relation to the spice event our analyses include the changing diversities of the phytoplankton acritarchs diverse groups of zooplankton e g radiolarians graptolites chitinozoans and the switch to a planktonic mode of life of fossil groups e g arthropods molluscs that were part of the cambrian benthos and that later occupied pelagic niches in addition we focus also on data indicating evidence for a late cambrian to ordovician origin of planktotrophy in invertebrate larvae it can be concluded that none of the diversifications of the different planktonic organisms can be related directly to the spice event however a long term 10 20 million years oxygenation pulse related to the spice event might have fuelled the explosion of phytoplankton diversity observed in the latest cambrian early ordovician that led to completely modified trophic structures permitting an increase in diversity and abundance of plankton feeding groups during the ordovician

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

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

sedimentology and sequence stratigraphy of neoproterozoic and cambrian units across a craton margin hinge zone southeastern california and implications for the early evolution of the cordilleran margin abstract neoproterozoic basal cambrian strata exposed in eastern california represent the deposits of a craton margin hinge zone that formed in response to the fragmentation of the neoproterozoic supercontinent rodinia one unresolved question regarding the late neoproterozoic stratigraphy in the southwestern united states has been the interpretation of paleotectonic affinity for rocks deposited above the glaciogenic kingston peak formation of central concern has been attempts to identify the position in this stratigraphy where rift related sediments give way to passive margin deposits subsidence analyses suggest that rifting occurred near the start of the cambrian perhaps coincident with the feldspathic middle member wood canyon formation it rests on a disconformity that represents the base of the sauk supersequence and would likely represent the break up unconformity in subsidence analysis models middle member wood canyon and overlying lower middle cambrian strata extend far into the craton detailed sedimentary facies and sequence stratigraphic analysis of post kingston peak pre middle wood canyon rocks indicate that depositional facies in this succession distal alluvial through shallow subtidal are similar to units deposited on the stable craton further these pre sauk units which can be divided into multiple principally eustatically driven depositional sequences are correlated across long distances and even lap onto the edge of the stable craton we suggest the kingston peak formation is the principal rift generated deposit and the overlying thick predominantly siliciclastic section represents the basal deposits of the cordilleran passive margin kingston peak strata consist of thick coarse diamictites interbedded with turbidites such facies are unique in the overall stratigraphy but are similar to other known rift deposits although the age of the kingston peak formation is not well constrained and may be as young as 590 ma it may correlate with the rapitan sturtian glaciation 720 ma which would place middle wood canyon strata some 150 ma younger than the start of rifting

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

did changes in antarctic ice volume influence late holocene sea level lowering abstract there has been great debate over the last few decades on the magnitude and causes of relative sea level lowering during the late holocene the principal attributed causes are geodynamic rather than glacio eustatic an alternative partial cause is an increase in antarctic ice volume glaciological and glacial geological field evidence indicates that during the late holocene the antarctic alpine glaciers ice sheet margins and outlet glaciers have expanded and the ice sheet interior has thickened this is attributed to i an ice thickening in central east antarctica throughout the holocene which was caused by the 50 higher holocene snow accumulation rates than those during the glacial stage coupled with the slow reaction time for ice sheet velocities to respond to the increased accumulation and temperature and ii increased ice volume supplied by higher than mean holocene accumulation rates associated with a warmer climatic period between 4000 to 2500 years b p it is estimated that these effects could account for 1 0 0 2 m of the interpreted sea level lowering on mid oceanic islands with 0 7 0 1 m of lowering occurring between 4000 and 2500 years b p

spatial and temporal variability in the holocene sea level record of the south australian coastline abstract studies of past sea levels based on radiocarbon dated field samples suffer variously from compilation of information from disparate locations and the imprecise nature of the dated indicators geographic segregation and systematic elimination of poor samples from time depth data sets leads to improved interpretation of holocene sea level history an example is presented from southern australia where this is achieved through selection of higher resolution palaeoenvironmental indicators separation of transgressive from regressive populations and geographic regionalisation of data in southern australia fossil sea level indicators preserved in prograding coastal plain settings include seagrass sandflat mangrove samphire and chenier ridge organo sedimentary remains these provide sea level time depth data points with a variety of elevational and dating errors preserved organic remains at the transition from posidonia seagrass to intertidal sandflat environment and from sandflat to avicennia mangrove environment provide the most precise local data for tracing sea level change time depth plots of 233 dated sea level indicators from south australia generate a broad sea level envelope tracing the southern australian transgression from 10 000 to ca 6000 radiocarbon years bp followed by a more or less consistent level to the present finer details of sea level behaviour are only apparent after systematic selection separation and regionalisation of the data the data indicate a very rapid sea level rise in the early holocene at about 16 mm year reaching present levels at 6400 years bp this was followed by regionally variable regression and emergence of the land of 1 3 m a process that continues to the present the systematic increase from 1 to 3 m in the elevation of the 6400 year bp highstand with distance away from the shelf margin is consistent with a hydro isostatic origin for the emergence as predicted by geophysical models

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

relative sea level changes in the last 5500 years in southern brazil laguna imbituba region santa catarina state based on vermetid ages abstract twenty six new radiocarbon dates from vermetid shells collected in the southernmost sector of the brazilian rocky coast presented dates ranging from 5410 80 to 190 65 years b p with associated paleosea levels varying from 2 10 m to 0 20 m above present sea level the overall suggested trend of the relative sea level rsl declining until at least 190 years b p is somewhat contradictory to a proposed rsl rise in the last 1000 years in southern brazil the data also seem to undermine a more widely accepted rsl trend that suggests that at least two negative rsl oscillations occurred between 4100 and 3800 years b p and between 3000 and 2700 years b p the maximum elevation of the rsl in the holocene in southern brazil was possibly lower than that observed in most of the brazilian eastern coast discrepancies between ancient sea levels of similar ages are attributed to coincidental methodological problems to imprecisions in determining past relative sea levels and to possible changes in the geomorphology and wave climate close to shore during the last 5000 years a general trend of increasing 18 o with a reduction in age in the studied samples may suggest a gradual reduction of water temperature in the region during the same period

fallen arches dispelling myths concerning cambrian and ordovician paleogeography of the rocky mountain region high resolution sedimentologic biostratigraphic and stable isotope data from numerous measured sections across colorado reveal a complex architecture for lower paleozoic strata in the central cordilleran region a lack of precise age control in previous studies had resulted in misidentification and miscorrelation of units between separate ranges corrections of these errors made possible by our improved data set indicate the following depositional history the quartz rich sandstone of the sawatch formation was deposited during onlap of the precambrian erosion surface in the early late cambrian the overlying dotsero formation a regionally extensive carbonate and shale rich succession records blanket like deposition with only minor facies changes across the state an extremely widespread meter scale stromatolite bed the clinetop bed caps the dotsero formation in most areas however a latest cambrian erosional episode removed 9 11 m of the upper dotsero formation including the clinetop bed from just east of the homestake shear zone in the sawatch range eastward to the mosquito range the overlying manitou formation differs in character and thus in member stratigraphy on the east vs west sides of the state these differences were previously interpreted as the result of deposition on either side of a basement high that existed within the central colorado embayment or colorado sag a region of major breaching across the transcontinental arch this paleogeographic reconstruction is shown herein to be an artifact of miscorrelation biostratigraphic data show that the northwestern members of the manitou formation are older than the members exposed in the southeastern part of the state and that there is little or no overlap in age between the two areas this circumstance is the result of 1 removal of older manitou formation strata in the southeast by an unconformity developed during the rossodus manitouensis conodont zone and 2 erosion of younger manitou strata in central and western colorado along middle ordovician and devonian unconformities deciphering these complex stratal geometries has led to invalidation of long held views on western laurentian paleogeography during the cambrian and earliest ordovician specifically the existence of the colorado sag and a northeast trending high within the sag that controlled depositional patterns on either side the mid rossodus uplift and resultant unconformity eliminated any and all upper cambrian and lower ordovician deposits in southern colorado and northern new mexico and thus their absence should not be misconstrued as evidence for earlier nondeposition in this region lithofacies distribution patterns and isopach maps provide no evidence that highlands of the transcontinental arch existed in colorado prior to the mid rossodus age uplift event in fact regional reconstructions of earliest paleozoic paleogeography along the entire length of the purported transcontinental arch should be reevaluated with similarly precise biostratigraphic data to reconsider all potential causes for missing strata and to eliminate topographic elements not supported by multiple stratigraphic techniques this study illustrates how seriously paleogeographic reconstructions can be biased by the presumption that missing strata represent periods of nondeposition rather than subsequent episodes of erosion particularly in thin cratonic successions where stratigraphic gaps are common and often inconspicuous

glacial lake development and marine inundation deer lake area newfoundland canada topographically controlled deglaciation of an interior basin a large interior basin in west central newfoundland covering the area of modern deer lake grand lake sandy lake and birchy lake is connected to the sea by a narrow breach of a coastal mountain range during retreat of late wisconsinan glaciers this basin was occupied by a short lived glacial lake impounded by remnant ice in coastal fjords and drained by a spillway at the western end of the lake evidence for this lake is fragmentary and consists of strandline features that fall on a plane of elevation consistent with the post glacial isostatic tilt following collapse of the ice dams and subsequent lake drainage at some time prior to 12 220 yr bp the deer lake basin was inundated by the sea to an elevation of about 45 m a s l deltas were formed at the basin edges and thick successions of fine grained rhythmites blanketed the basin floor isostatic rebound resulted in falling relative sea levels and following a stillstand marked by a period of deltaic deposition at 33 m a s l isolation of the deer lake basin from marine influence in the early holocene this style of deglaciation differs from previously accepted models for this part of eastern canada which showed progressive retreat from the coast to remnant centres on topographic highs in the model proposed here a large low elevation basin was deglaciated early at a similar time to ice retreat to coastal positions from offshore this pattern of deglaciation may be found in other areas with similar topographic settings

climatically controlled river terrace staircases a worldwide quaternary phenomenon a comparison of fluvial terrace sequences from around the world based on data collected as part of international geoscience programme igcp project no 449 has revealed significant patterns river terraces provide important records of uplift which is essential for their formation and of landscape evolution their cyclic formation however almost invariably seems to have been a response to climatic fluctuation sequences in the european core area of igcp 449 which has the longest and most extensive research history have been used as templates for worldwide comparison there is evidence for a global acceleration of uplift at the time of and perhaps in response to the mid pleistocene revolution when climatic fluctuation switched to 100 kyr milankovitch cycles terraces formed prior to this generally consist of wide aggradational sheets that probably each represent formation over several 41 kyr cycles subsequently river valleys became more steeply entrenched and terraces formed in response to the stronger 100 kyr climatic forcing in many cases at approximately one per cycle this paper uses the new data resource to explore differences between records in different climate zones between sequences with variable numbers of middle late pleistocene terraces and between systems in which the all important incision event has occurred in different parts of climatic cycles key records discussed include european examples from the rhine thames somme dniester dnieper don volga and aguas from asia the gediz turkey and orontes syria from north america the south platte and colorado from south africa the vaal and sundays from australia the shoalhaven and from south america the amazon paraguay and tributaries of the colorado and negro

the brazilian sea level curves a critical review with emphasis on the curves from the paranaguaand cananeia regions abstract relative sea level curves for the mid to late holocene have been proposed for eight different sectors along the brazilian coast this paper aims to review the data used to construct the curves proposed for two sectors the paranaguaand cananeia regions in southeast brazil more specifically we analyze the palaeo sea level indicators vermetid tubes shells wood fragments and shell midden deposits related to 1 the sea level maximum of the mid holocene and 2 the two secondary oscillations that would have occurred between 4100 3800 years b p and 3000 2700 years b p the sedimentary deposits of the coastal plain as well as vermetid datings suggest a mid holocene sea level maximum between 3 5 and 4 m the great majority of the indicators used to infer the secondary oscillations in previous studies were derived from shell middens besides being unreliable palaeo sea level indicators these data also showed inconsistencies that undermine the existence of such oscillations the plot of all the data derived from vermetid samples found along the brazilian coast also indicate a rather smoother sea level fall in the last 5100 years

glacial rebound and sea level change an example of a relationship between mantle and surface processes lambeck k 1993 glacial rebound and sea level change an example of a relationship between mantle and surface processes in r wortel u hansen and r sabadini editors relationships between mantle processes and geological processes at or near the earth s surface tectonophysics 223 15 37 the problem of glacial rebound provides an outstanding example of the relationship between surface and mantle processes on time scales of 103 to 105 years changes in surface loading of ice and melt water associated with the growth and decay of the great ice sheets deform the surface of the planet and induces flow in the mantle a measure of the earth s response to the changing surface loads and internal deformation is provided by observations of past sea levels relative to the present level and inversion of these observations provides constraints on both the models of the rheological response of the earth to loading and on models of the ice sheets constraints on ice sheet models include the total volume of the grounded ice at the time of maximum glaciation the global rates of melting of the ice sheets the thickness of the ice at maximum glaciation the extent of ice cover over shallow seas such as the north sea and the barents sea and the role of antarctica in the global ice balance constraints on mantle parameters include the effective lithospheric thickness and the effective viscosity of the mantle some recent results for both sets of parameters are discussed

further evidence from relic shellcrust sequences for a late holocene higher sea level for eastern australia abstract new evidence from dating the fossil residue of intertidal organisms on the central new south wales coast extends the findings of an earlier use of this method and supports the case for a regional highstand between 1 and 2 m above present relative sea level for much of the middle to late holocene evidence demonstrating a vertical shift over time by in situ intertidal organisms provides a more precise record of holocene sea level fluctuation than the more ambiguous evidence from estuarine and dunal depositional features by extrapolating back from dated hard evidence of this kind secondary evidence such as remnant rock platforms may be used to reconstruct the age and duration of coastal geomorphic features

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