conceptual models of the evolution of transgressive dune field systems abstract this paper examines the evolutionary paths of some transgressive dune fields that have formed on different coasts of the world and presents some initial conceptual models of system dynamics for transgressive dune sheets and dune fields various evolutionary pathways are conceptualized based on a visual examination of dune fields from around the world on coasts with high sediment supply dune sheets and dune fields tend to accumulate as large scale barrier systems with little colonization of vegetation in arid hyper to arid climate regimes and as multiple active discrete phases of dune field and deflation plain couplets in temperate to tropical environments active dune fields tend to be singular entities on coasts with low to moderate sediment supply landscape complexity and vegetation richness and diversity increases as dune fields evolve from simple active sheets and dunes to single and multiple deflation plains and basins precipitation ridges nebkha fields and a host of other dune types associated with vegetation e g trailing ridges slacks remnant knobs gegenwalle ridges and dune track ridges tree islands and bush pockets three principal scenarios of transgressive dune sheet and dune field development are discussed including dune sheets or dune fields evolving directly from the backshore development following foredune and or dune field erosion and development from the breakdown or merging of parabolic dunes various stages of evolution are outlined for each scenario knowledge of evolutionary patterns and stages in coastal dune fields is very limited and caution is urged in attempts to reverse change and or modify dune fields to restore some perceived loss of ecosystem or dune functioning

sedimentary processes in the river dominated mvoti estuary south africa abstract the mvoti river enters the indian ocean on the natal coast of south africa in its lower reaches the river comprises a narrow shallow channel that traverses a broad floodplain at the coast an outlet to the sea is maintained through a sandy barrier across an underlying rock outcrop seawater intrusion through the outlet is prevented by the elevation of the rock outcrop and hence reversing currents and tidal salinity variations typical of estuaries are not developed in the lower reaches of the river sedimentary deposits and processes in the back barrier area are predominantly fluvial and the system is best classified as a river dominated estuary a lack of coastal progradation prevents its definition as a delta the greatest geomorphological impacts in the channel and barrier are caused by extreme river floods sedimentary processes revealed by aerial photography and field measurements in the mvoti show changes in response to discharge variation within the normal range of discharge variation the channel varies in dimension and morphology but no major long term buildup of sediment is evident in the floodplain or channel minor floods deposit muddy overbank deposits during such floods the channel gradient is increased by barrier breaching and channel shortening but wave dominated barrier processes act to close the breach rapidly superimposed on these short term changes is a cyclic pattern driven by major floods which cause lateral channel erosion and overbank deposition post flood recovery involves progressive channel confinement and stabilisation as flow reverts to a single or braided channel and the floodplain is re vegetated after major floods the channel assumes a position in the centre of the floodplain but subsequently it shows a tendency to migrate to the edge of the floodplain and elongate its channel current incorrect perceptions of the river mouth area as an estuary degraded by siltation are based on a comparison of present morphology with typical wave dominated estuaries and lack of recognition of the mvoti as one of a suite of river dominated estuaries the study highlights the need for a suite of universally applicable models not only for estuaries but for transitional fluvio marine environments in general

measurement and estimation of pore shrinkage and pore distribution in a clayey till during soil water characteristic curve tests the soil water characteristic curve swcc of fine grained soils is usually determined experimentally in many applications such as design of mine waste covers and landfill liners the unsaturated permeability function k h is often derived theoretically from the measured swcc implicit in these derivations is the transformation of the swcc to a pore size distribution psd typically assumed to be constant and mono modal psds of a clayey till compacted at various water contents were measured after compaction after flexible wall permeability testing and during and after swcc tests the measurements show that the psd changes significantly during permeability and swcc testing a method is advanced for predicting the observed changes in psd during swcc testing psds are determined for soil samples subjected to the highest and lowest suctions applied during the swcc test the measured psds are transformed to account for pore trapping the transform assumes that flow occurs through two sets of randomly d

bayhead deltas and shorelines insights from modern and ancient examples abstract bayhead deltas are important components of the rock record as well as modern estuaries hosting important hydrocarbon reservoirs and many coastal cities ports and large expanses of wetlands despite their significance few studies have summarized their occurrence and sedimentary characteristics in this paper we review the stratigraphic sedimentary and geomorphic characteristics of 68 modern and ancient bayhead deltas bayhead deltas are found in incised valleys structural basins fjords interdistributary bays of larger open ocean deltas and other backbarrier environments except for within fjords they generally prograde into shallower and more brackish waters than their open ocean equivalents as a result 80 of modern 68 of quaternary and 67 of ancient bayhead deltas have clinoform thicknesses of 10 m or less with 73 of modern bayhead deltas having clinoform thicknesses of 5 m or less additionally 89 of modern 81 of quaternary and 77 of ancient bayhead deltas examined are fluvial dominated we distinguish true bayhead deltas from their genetically similar bayhead shorelines which are not constructional features but sites of enhanced marsh or estuarine sedimentation near river mouths with inadequate rates of sediment delivery to form distributary channels and prograde into the estuary or lagoon we also distinguish confined bayhead deltas found in incised valleys structural basins and fjords from unconfined bayhead deltas found as incipient lobes of larger delta complexes and other back barrier lagoons the architecture of confined bayhead deltas is largely influenced by the limited accommodation brought about by the walls of the flooded valleys in which they are located as such confined bayhead delta ontogeny is controlled by many autogenic interactions within these valley walls both confined and unconfined bayhead deltas are sensitive to sea level rise climate controlled changes in sediment flux and tectonics their relatively small size connection with the terrestrial system and protected nature make them the ideal depositional system to record earth history including sea level and climate changes

quantification of the ice cored moraines short term dynamics in the high arctic glaciers ebbabreen and ragnarbreen petuniabukta svalbard abstract extensive ice cored moraine complexes are common elements marking the last advance of many svalbard glaciers sediment gravity flows are among the most dynamic processes transforming these landforms the short term yearly and weekly dynamics of mass wasting processes were studied in a cm scale using repetitive topographic scanning we monitored several active sites on the forelands of two glaciers ebbabreen and ragnarbreen both of which are located near petuniabukta at the northern end of billefjorden in spitsbergen the surveys indicate high dynamic rates of landforms transformation the mean annual volume loss of sediments and dead ice for the most active parts of the moraines was up to 1 8 m a 1 however most of the transformation occurred during summer with the short term values of mean elevation changes as high as 104 mm day 1 in comparison the dynamics of the other i e non active parts of the ice cored moraines were much lower namely the mean annual lowering attributed mainly to dead ice downwasting was up to 0 3 m a 1 whereas lowering during summer was up to 8 mm day 1 our results indicate that in the case of the studied glaciers backwasting was much more effective than downwasting in terms of landscape transformation in the glacier forelands however despite the high activity of localised mass movement processes the overall short term dynamics of ice cored moraines for the studied glaciers were relatively low we suggest that as long as debris cover is sufficiently thick thicker than the permafrost s active layer depths the mass movement activity would occur only under specific topographic conditions and or due to occurrence of external meltwater sources and slope undercutting in other areas ice cored moraines remain a stable landsystem component in a yearly to decadal time scale

sea level control of stacked late quaternary coastal sequences central great barrier reef lithofacies analysis pollen assemblages and radiocarbon age dates of 20 stratigraphic drill holes are used to develop an evolutionary history for late quaternary sedimentation in two coastal embayments landward of the central great barrier reef different physiographic settings of the embayments result in two contrasting styles of sedimentary sequence a an exposed moderate energy beach barrier lagoon system wyvuri embayment and b a protected low energy muddy inlet fill sequence mutchero inlet despite sharp contrast in sequence style similar depositional cycles occur in both embayments in response to late quaternary sea level fluctuations including 1 a last interglacial highstand 2 m c 125 000 yr bp beach barrier wyvuri 2 an early to mid holocene 8000 6100 yr bp transgressive beach barrierlagoon wyvuri and estuarine infill mutchero and 3 mid holocene to present highstand beach barrier wyvuri and estuarine mutchero progradation preservation of such cycles in the stratigraphic record would produce a series of vertically stacked and offset linear barrier sands surrounded by lagoonal mud and fine grained shoreface sediment juxtaposed to muddy estuarine infills sea level elevations are well recorded by the upward transition from rhizaghoru dominated intertidal mangrove mud to freshwater swamp clearly identified by pollen analysis and by the basal contacts of beach barrier sediments which sharply overlie the upper shoreface transgressive sedimentation is interrupted in both embayments by a constructional beach barrier wyvuri and abbreviated progradation mutchero corresponding to a 5 m pause in relative sea level rise at c 6800 yr bp sea level control of fine scale coastal sedimentation patterns is beginning to be widely recognized and provides an accurate analogue for stacked ancient sequences

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

beach ridge development and sediment supply examples from west africa abstract beach ridges form the dominant mode of holocene coastal progradation in west africa they vary from minor accumulations to massively prograded plains over 100 km long variations in the patterns and morphological expression of these sandy deposits record spatial and temporal changes in various environmental parameters among these sediment supply stands out the importance of this factor is illustrated by the morphological patterns and the current sediment dynamics of minor and major beach ridge plains in this region the simplest beach ridges are related to just one or two sources of sand supply from a nearby source in these examples sand has been supplied by the nearshore zone or by eroding cliffs in many areas beach ridge formation ceased as the sediment supply dwindled because of cliff stabilization or establishment of an equilibrium nearshore profile major beach ridge plains in southern sierra leone and in the bight of benin exhibit complex patterns of development related to a bigger sediment supply from nearshore sources and rivers in southern sierra leone the beach ridge plains have been constructed essentially from sands derived from the nearshore zone locally as in the proximal part of sherbro island shallow nearshore shoals encroached upon by the beach ridge front have led to more massive progradation while engendering complex patterns of beach ridge development the sediment supply has been locally supplemented by sands drifting alongshore from the sewa and moa rivers the sediment supply involved in beach ridge development in the bight of benin highlights the role of longshore drift of sands from the volta delta early stages of progradation were characterized by the development of segmented inner beach ridge barriers separated by still infilling coastal re entrants nearshore sources were particularly important in these early stages of beach ridge progradation as coastal re entrants and their estuaries became infilled following the middle holocene eustatic highstand the longshore drift system evolved from a segmented to a unicellular one the resulting conditions of through drift east of the volta delta allowed for longshore transport of sands from this river for the construction of outer beach ridge barriers over a distance of over 250 km while rivers still actively supply sand to the coast current patterns of beach ridge development depend essentially on the coastal sand transport system which determines either the confinement of incoming sand to the vicinity of the very source area itself its regular delivery to the beach ridge front or its through drift to the local downdrift terminus

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

little ice age glacier extent and subsequent retreat in svalbard archipelago the influence of the little ice age lia on the glaciers of svalbard has been well documented for a long time this paper presents new data on the lia maximum glacier extent and retreat by aeria

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

beachrock formation in low latitudes implications for coastal evolutionary models abstract beachrock is present in many parts of the world particularly on low latitude coastlines its formation during stillstands or minor regressions in subtropical areas involves cementation of clastic grains and thus prevents grain transport in the littoral zone during later transgression or regression existing short and medium term conceptual and numerical models of coastal evolution fail to take into account this effective reduction of littoral sand supply and the effects of the beachrock itself on shoreline development in the short term reduction of sediment supply through beachrock formation during transgression should enhance landward translation of the shoreline conversely the beachrock itself may afford a degree of protection from erosion in the medium to long term beach rock formation during multiple pleistocene transgressions and regressions in areas which lack significant sediment input from land drainage systems may have caused a long term reduction in sediment volume during the course of the pleistocene this assumes that beachrock formation is not matched by its destruction through physical and bioerosion and chemical weathering preservation of coastal facies is greatly enhanced by beachrock formation which may promote overstepping and drowning of strandline facies during transgression or preferential preservation during regression precise records of sea level fluctuations may be preserved by beachrock formation a situation rendered almost impossible in other areas due to littoral transport of mobile sediment in the widespread areas in low latitudes where it occurs beachrock formation may be an important element in models of horizontal shoreline displacement and coastal evolution

tidally flooded back barrier dunefield guerrero negro area baja california mexico a 45 km long barrier island exists west of the town of guerrero negro mexico along the western coast of the baja california peninsula about 720 km south of san diego california this barrier has developed in a mesotidal arid climate regime characterized by steady strong onshore winds from the nw the barrier island w of guerrero negro has prograded seaward about 1 6 km in the last 1800 years while an aeolian dunefield fed by sand blown from beaches has advanced inland up to 13 km landward progradation of the dune system from the barrier has occurred during relative rise in sea level thus aeolian sediments exist at or below the water table over a wide area the progradation of dunes across marshes tidal flats and tidal channels as well as the repeated submergence of interdune areas by tidal waters has created a complex suite of mixed aeolian and subaqueous sediments in the back barrier the complexity of the suites of aeolian sedimentary structures together with the inclusion of subaqueously formed structures such as current and oscillation ripples would make recognition of the aeolian origin of much of the sediments difficult in ancient rocks in addition to the scientific importance of recognizing the aeolian deposits the sedimentation model represented by the guerrero negro barrier has applications in petroleum exploration and development currently most preservational models for barrier islands attach little volumetric importance to aeolian deposits this modern example suggests that volumetrically significant aeolian deposits can be preserved behind a barrier particularly in an arid climate regime if preserved and charged with oil the resulting productive sandstone could have an extremely irregular landward edge comprised in part of onshore prograded aeolian dune sandstone with excellent reservoir characteristics as with current barrier models the reservoir would be sealed landward and above by lagoonal mudstone and silt evaporites or evaporitic sandy sabkha deposits high organic productivity occurs in lagoons immediately adjacent to the dunefields of guerrero negro suggesting that organic rich source rock may exist near aeolian sandstone in ancient settings similar to guerrero negro

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

shoreline recovery on wave dominated sandy coastlines the role of sandbar morphodynamics and nearshore wave parameters abstract this study quantifies and characterises the temporal variability of shoreline recovery on a high energy sandy coastline using a 10 year dataset of daily shoreline and sandbar positions from a coastal imaging station at narrabeen collaroy beach australia following a total of 82 individual storm events rates of the cross shore return of the shoreline to its pre storm position were analysed observed rates during shoreline recovery were characterised by an overall mean of 0 2 m day temporal variability in rates was most evident at shorter timescales of 1 2 weeks and included rates most frequently between 0 and 0 3 m day less frequent more rapid rates of up to 2 m day and also minor landward movements this temporal variability was significantly correlated with nearshore forcing parameters describing the ratio of wave height to wave period the cross shore proximity and attachment of the sandbar to the shoreline and the rate of cross shore sandbar migration these findings are summarised in a new conceptual model that characterises temporal phases and rates of shoreline recovery corresponding to stages of onshore sandbar migration following a storm from fully detached storm deposited sandbar morphology through to complete sandbar welding with the shoreline more gradual shoreline recovery rates are observed with fully detached and semi attached sandbar conditions in contrast more rapid rates of shoreline recovery occur when sandbars are closer and attached to the shoreline observed to be on average 3 4 times greater than for detached sandbars in conditions with attached and semi attached sandbars shoreline recovery rates are negatively correlated to the forcing of nearshore wave steepness and dimensionless fall velocity and coupled with concurrent rates of onshore sandbar migration the findings provide insight into key parameters influencing shoreline recovery following storms

an inlet sequence produced by migration of a small microtidal inlet against longshore drift the keurbooms inlet south africa lateral migration of the keurbooms inlet along its barrier causes stratigraphic stacking of the different sedimentary units in the inlet area thus accumulating an inlet sequence under the newly formed barrier deposition in the inlet is controlled by wave and tidal action migration is caused by sediment accretion on the downdrift side of the inlet and erosion on its updrift side the migration direction is therefore in the opposite direction to the longshore current this is comparatively rare as most inlets with a tendency to migrate do so in the same direction as longshore drift tidal current directions in the inlet are highly variable and not bipolar the inlet associated environment is divided into a seaward wave dominated zone and a landward tide dominated zone these zones probably have laterally interfingering facies only the lower part of the sequence is likely to be preserved recognition of ancient analogues in the rock record may be obscured by the unidirectional palaeocurrent pattern of the lower part of the inlet sequence

accommodation space in a high wave energy inner shelf during the holocene marine transgression correlation of onshore and offshore inner shelf deposits 0 12 ka in the columbia river littoral cell system washington and oregon usa abstract the columbia river littoral cell crlc a high wave energy littoral system extends 160 km alongshore generally north of the large columbia river and 10 15 km in across shelf distance from paleo beach backshores to about 50 m present water depths onshore drill holes 19 in number and 5 35 m in subsurface depth and offshore vibracores 33 in number and 1 5 m in subsurface depth constrain inner shelf sand grain sizes sample means 0 13 0 25 mm and heavy mineral source indicators 90 holocene columbia river sand of the inner shelf facies 90 fine sand stratigraphic correlation of the transgressive ravinement surface in onshore drill holes and in offshore seismic reflection profiles provide age constraints 0 12 ka on post ravinement inner shelf deposits using paleo sea level curves and radiocarbon dates post ravinement deposit thickness 1 50 m and long term sedimentation rates 0 4 4 4 m ka 1 are positively correlated to the cross shelf gradients 0 36 0 63 of the transgressive ravinement surface the total post ravinement fill volume of fine littoral sand 2 48 1010 m3 in the inner shelf represents about 2 07 106 m3 year 1 fine sand accumulation rate during the last 12 ka or about one third of the estimated middle to late holocene columbia river bedload or sand discharge 5 6 106 m3 year 1 to the littoral zone the fine sand accumulation in the inner shelf represents post ravinement accommodation space resulting from 1 geometry and depth of the transgressive ravinement surface 2 post ravinement sea level rise and 3 fine sand dispersal in the inner shelf by combined high wave energy and geostrophic flow down welling drift currents during major winter storms

sea level sediment supply and coastal changes examples from the coast of ireland abstract sediment supply and pre existing shoreline morphology are crucial factors in controlling coastal changes due to sea level rise using examples from both southeast and northeast ireland it can be shown that sea level change may trigger a sequence of events which leads to both static and dynamic shoreline equilibrium cliff erosion and longshore sediment movement in east co wexford has led to injection of sediment onto the shelf and the growth under both wave and tide regimes of linear offshore shoals these shoals now control the pattern of shoreline erosion and provide a template for possible stepwise evolution of the coast under any future sea level rise in contrast the nearby coast of south co wexford comprises a series of coarse clastic barriers moving monotonously onshore via overwash processes here the behavior of the barrier is conditioned by the antecedent morphology of both the beach face and stream outlet bedforms finally the rock platform coast of co antrim presents a far more resistant shoreline to incident marine processes yet even here there is strong evidence of present process control over so called raised platforms and embayments it is concluded that coastal sediment supply and dynamics together with coastal morphology and its interaction with waves present a far more complex variety of sea level indicators than is normally acknowledged

the last interglacial shoreline in australia a review abstract marginal marine strata of last interglacial age occur in a range of morphostratigraphic settings around the australian coastline the lithofacies are similar to their holocene equivalents but are partly lithified elevated and laterally displaced inland uranium series ages for corals and molluscs from widely separated localities around the australian coastline are generally in accord with the accepted age for oxygen isotope substage 5e 125 000 10 000 bp the value generally accepted for the last interglacial maximum amino acid racemisation has principally been applied to correlation of sequences with benchmark sites dated by the uranium series method elevations of preserved last interglacial shorelines do not support the notion that australia is a stable continent significant neotectonic anomalies include cape cuvier 10 5 m fleurieu peninsula 6 m the coorong coastal plain 10 m and tasmania 32 m each indicating contrasting degrees of local uplift the tasmanian sequences are the highest occurrence on the australian continent and have been attributed to uplift as a result of mantle hotspot processes with the exception of these tectonically uplifted sites the height of the last interglacial sea surface around the australian coastline is consistently below the 6 m level globally attributed to this high sea level stand in australia the most consistent datum is from western eyre peninsula where a level 2 m above present mean sea level is ubiquitous the more southerly limit of coral growth and wider distribution of subtropical molluscan fauna are in accordance with warmer ocean waters during substage 5e approximately 2 c the extent of racemisation in molluscan fossils from southern australia also excludes the possibility of a more equable latitudinal distribution of mat during substage 5e

last glacial coastal dunes in eastern australia and implications for landscape stability during the last glacial maximum abstract the last glacial maximum or lgm 25 000 15 000 yr b p has been recognized in australia as a period of increased dryness coolness continentality and windiness compared to earlier and later period enhanced aeolian activity during the lgm occurred in arid and semi arid regions of western central and eastern australia the east coast has been considered to have been better watered and vegetated however at a number of sites from tasmania to north queensland there is evidence for extensive aeolian instability of coastal sand deposits dating by radiocarbon and thermoluminiscence techniques has supported morphologic and stratigraphic evidence of dune formation during the lgm under the influence of westerly offshore winds in the southern sector of the east coast i e south of 31 s latitude and southeast winds to the north it is now apparent that vegetation cover on sandy surfaces was quite patchy during the lgm sand surface instability under conditions of strong west or southeast winds promoted linear and or parabolic dune development this suggests greater concentration of forests in more discrete protected sites along the eastern escarpment than was previously considered by palaeoecologists more widespread drier and cooler climatic conditions operated even in coastal regions on expanded continental shelves at this time stabilization of areas of active dunes became more likely as sea levels rose reduced windiness occurred and precipitation increased as sea surface temperatures began to rise in the holocene

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

late quaternary sea level change in south africa abstract a late quaternary sea level curve for south africa is presented on the basis of new and published data from a range of sea level indicators and a variety of locations available evidence suggests that sea level in south africa broadly follows that described from the caribbean but that deviations occur during sea level highstands during the last interglaciation oxygen isotope stage 5 and the late holocene coastal emergence produced higher sea levels in south africa than those identified in the caribbean during the same time intervals this is tentatively ascribed to predicted lithospheric deformation in continental margin settings

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

from river to shelf anatomy of a high frequency depositional sequence the late pleistocene to holocene tiber depositional sequence the late pleistocene holocene tiber delta succession represents the most recent and one of the best preserved high frequency low rank depositional sequences developed along the latium continental margin of the italian peninsula several previous studies have established a robust data set from which it has been possible to describe the stratigraphic architecture of the entire tiber depositional sequence from the landward to seaward sectors and over a distance of 60 km the tiber depositional sequence shows many characteristics found in other late pleistocene to holocene deltaic and coastal successions of the mediterranean area the stratigraphic architecture of the tiber depositional sequence is controlled mainly by glacioeustasy although factors such as tectonic uplift volcanism and subsidence exert an influence at a local scale the resulting depositional model allowed discussion of some important points such as 1 the genesis of the tiber mixed bedrock alluvial valley extending from the coastal plain to the innermost portion of the shelf recording i multiple episodes of incision during relative sea level fall and ii a downstream increase of depth and width of the valley during the base level fall and the subsequent base level rise 2 the different physical expression of the tiber depositional sequence boundary from landward to seaward and its diachronous and composite character 3 the maximum depth reached by the tiber early lowstand delta at the end of the sea level fall is estimated at ca 90 m below the present sea level and not at 120 m as suggested by previous works 4 the backward position of the tiber late lowstand delta relative to the deposit of early lowstand 5 the change of the channel pattern and of the stacking pattern of fluvial deposits within the lowstand systems tract transgressive systems tract and highstand systems tract all of these features indicate that the late pleistocene holocene tiber delta succession even if deposited in a short period of time from a geological point of view represents the result of the close interaction among many autogenic and allogenic factors however global eustatic variations and sediment supply under the control of climatic changes can be considered the main factors responsible for the stratigraphic architecture of this sedimentary succession which has been heavily modified by human activity only in the last 3000 years

mangroves and intertidal morphology in westernport bay victoria australia abstract westernport bay a marine system produced by holocene submergence of a sunkland was initially a mainly sandy embayment but erosion and dispersal of clay derived from bordering freshwater swamps and weathered basalt cliffs has resulted in the formation of extensive tidal mudflats the upper part of the intertidal zone consists of a salt marsh terrace fringed seaward by mangroves avicennia marina field measurements have shown sustained accretion under this mangrove fringe in contrast with alternations of erosion and accretion on the mudflats to seaward and the trapping of sediment by mangrove pneumatophore networks has been demonstrated by surveys and simulated experimentally it is deduced that the mangroves have here shaped the pattern of sedimentation in such a way as to build a depositional terrace at high spring tide level on which they have been succeeded by salt marsh communities where the mangrove fringe has died back or been cleared away this terrace has been degraded to an intertidal wave cut platform but where the mangroves have revived after such an episode the depositional terrace is being rebuilt it is concluded that mangroves have influenced the geomorphology of the shores of westernport bay

late quaternary evolution of coastal sand barriers port stephens myall lakes area central new south wales australia abstract the geomorphic and stratigraphic history of six coastal embayments has been studied in the vicinity of newcastle new south wales n s w australia in order to determine modes of deposition and the degree to which marine and estuarine deposits can be correlated and dated each embayment possesses its own distinctive suite of landforms ranging from those dominated by coastal dunes to those in which beach ridges occur in four of the bays dual sand barriers comprising an inner barrier and an outer barrier provide the framework for correlation between embayments six stages are recognized in the deposition of late quaternary sediments in this area i pre last interglacial involving accumulation of separate composite units consisting of estuarine clays and transgressive dune complexes ii last interglacial stage during which inner barriers were formed iii last glacial reworking of barrier and dune sands by westerly winds iv postglacial marine transgression during which the outer barriers were initiated v mid holocene stage following cessation of sea level rise ca 6000 6500 yr b p on this coast and involving progradation of outer barriers in some embayments and vi late holocene episodic eolian reworking of dune complexes and outer barriers the relatively high wave and wind energy as well as the tectonic setting of the central n s w coast results in somewhat different geomorphic histories from barrier island coasts in north america and europe

hydrology and hydrochemistry of a deglaciating high arctic catchment svalbard summary the impact of deglaciation on contemporary hydrological and biogeochemical functioning in the rieperbreen foxfonna catchment in western svalbard was observed in 2007 2008 an overall negative mass balance was observed during 2007 mass loss was high below the equilibrium line altitude ela but spatially patchy mass increases due to superimposed ice and firn were evident above the ela runoff from above the ela was almost exclusively routed through low gradient hydraulically inefficient supraglacial flowpaths which fed steeper highly efficient supraglacial and englacial subglacial channels downstream as interaction with debris rich environments subglacial and proglacial was minimal and transit times were rapid below the ela runoff from supraglacial sources had a low solute content in addition two further parallel hydrological pathways existed snowmelt fed springs emerging from the glacier s contemporary marginal moraines and multiple shallow intermittent streams within recent moraines throughout the glacier forefield and along its northern moraine flank runoff from these additional pathways flowed through highly reactive sediments composed of shale carbonate and sandstones their intense chemical and physical weathering meant moraines were important sources of solute contribution to the catchment s bulk runoff chemistry ecological succession at the glacier margin is therefore highly likely to be dependent upon nutrient acquisition by hydrological processes within moraines as the catchment undergoes deglaciation

late pleistocene sea level oscillations mis 10 2 recorded in shallow marine and coastal plain sediments of the southern wanganui basin new zealand abstract the northern wanganui basin new zealand is one of the key global sites for understanding marine cyclic sedimentation during the quaternary this paper presents the first evidence of marine cyclic sedimentation from its central southern parts sedimentological micropalaeontological and palynological analyses on a 280 m deep borehole encountered units dating back to mis 10 the sequence includes four marine cycles spanning mis 9 5 which are overlain by terrestrial fluvial aggradation surfaces dating from mis 4 2 each marine unit represents a progressively shallowing depositional environment from the mid shelf to coastal plain this is overlain by a terrestrial sequence of lowstand fluvial terraces localized fault movements appear to have influenced the sedimentary character of the sequence during mis 7a and 5e producing basement highs which provided protection to the shoreline the cyclothems described in this paper now extend the already extensive previously described record from mis 17 10 to produce a combined eustatic record of quaternary sea level change within the basin to mis 5 they also provide an excellent example of the sedimentary response of a coastal basin to a progressive loss of sedimentation accommodation space

holocene evolution of the ninety mile beach sand barrier victoria australia the role of sea level sediment supply and climate abstract the ninety mile beach nmb barrier system in southeastern australia is the largest active barrier island system in australia the response of a sandy barrier system to a warming climate is dependent on the boundary conditions of sediment supply and sea level deposition during the holocene can therefore provide an indication of how these barriers may change in the future in this study airborne lidar ground penetrating radar and subsurface coring were combined with 46 optically stimulated luminescence and 32 radiocarbon ages to provide a detailed understanding of sedimentation of nmb through the holocene the barrier complex formed in three distinct phases dating back to the earliest stabilisation of sea level after the postglacial marine transgression first restriction of the flooded open ocean embayment that had formed around a last interglacial beach barrier sequence occurred with accretion of an island complex at around 8000 years bp sourced from transgressive sands reworked from the shelf in the second phase at around 6000 years bp a second barrier island formed seaward of the last interglacial barrier but disconnected from the earlier holocene barrier islands by a large tidal inlet waning sediment supply from the shelf meant that aggradation of these islands slowed by 4000 years bp the third and final phase occurred after 3000 years with the initiation of sediment supply at the southwestern end of the barrier the island system which formed seaward of the last interglacial barrier then prograded by several hundred metres and elongated in a northeasterly direction by tens of kilometres infilling the tidal inlet and enclosing the earliest holocene barrier landward of a newly created lake sediment supply appears to be the primary limiting factor in the development of nmb with indications of a change in wave climate and sea level have an influence on barrier evolution

complex coastal change in response to autogenic basin infilling an example from a sub tropical holocene strandplain thick bay fill sequences that often culminate in strandplain development serve as important sedimentary archives of land ocean interaction although distinguishing between internal and external forcings is an ongoing challenge this study employs sediment cores ground penetrating radar surveys radiocarbon dates palaeogeographic reconstructions and hydrodynamic modelling to explore the role of autogenic processes notably a reduction in wave energy in response to coastal embayment infilling in coastal evolution and shoreline morphodynamics following a regional 2 to 4 m highstand at ca 5 8 ka the 75 km2 tijucas strandplain in southern brazil built from fluvial sediments deposited into a semi enclosed bay holocene regressive deposits are underlain by fluvial sands and a pleistocene transgressive regressive sequence and backed by a highstand barrier island the strandplain is immediately underlain by 5 to 16 m of seaward thickening fluvially derived holocene age basin fill mud several trends are observed from the landward oldest to the seaward youngest sections of the strandplain i the upper shoreface and foreshore become finer and thinner and shift from sand dominated to mud dominated ii beachface slopes decrease from 11 to ca 7 and iii progradation rates increase from 0 4 to 1 8 m yr 1 hydrodynamic modelling demonstrates a correlation between progressive shoaling of tijucas bay driven by sea level fall and sediment infilling and a decrease in onshore wave energy transport from 18 to 4 kw m 1 the combination of allogenic sediment supply falling relative sea level and geology and autogenic decrease in wave energy due to bay shoaling processes drove the development of a regressive system with characteristics that are rare if not unique in the holocene and rock records these findings demonstrate the complexities in architecture styles of highstand and regressive systems tracts furthermore this article highlights the diverse internal and external processes and feedbacks responsible for the development of these intricate marginal marine sedimentary systems

a full sea level cycle in 65 years barrier dynamics along caspian shores abstract the caspian sea being a closed basin shows much higher rates of sea level change up to 340 mm yr than the oceans it experienced a full sea level cycle with an amplitude of 3 m between 1929 and 1995 its coasts therefore present an attractive physical model to test predicted changes along oceanic coasts as a result of expected eustatic sea level rise and to validate sequence stratigraphical interpretations of ancient sediments along the wave dominated coasts with intermediate shore face slopes in dagestan low onshore bars were formed during the 1929 1977 sea level fall they represent minor short lived 1 2 years transgressive oscillations within the major regressional trend after the 1977 lowstand a prominent barrier lagoon system was formed which during the first phase of sea level rise 1977 1988 encroached landwards about 18 m each year by washover during storms continuous retreat between 1988 and 1995 however barrier size diminished lagoons widened and deepened apparently due to lack of coarse grained sediment supply discontinuous retreat the 1995 highstand prevented the barriers from being overstepped altogether sea level fall after 1995 again produced low bars without lagoons the caspian sea barrier coast demonstrates that for the formation of barrier lagoon complexes the combination of transgression and storms is essential barriers may show either continuous or discontinuous development at constant rate of sea level rise and constant offshore slope depending essentially on the availability of coarse grained sediments the rate of sea level rise as a factor in barrier behaviour cannot be viewed independently from barrier dimensions which in turn depend on wave base depth and maximum storm wave height relations between para sequence thickness and frequency and amplitude of sea level change in closed basins with an independent sea level regime may differ markedly from those in basins influenced by eustasy

foredunes and blowouts initiation geomorphology and dynamics this paper reviews the initiation dynamics geomorphology and evolution of incipient foredunes established foredunes and blowouts incipient foredunes may be initiated in a variety of ways leading to the formation of ramps terraces or ridges depending on progradation rates vegetation type and cover sediment transport rates and scale of erosional processes vegetation cover morphology growth rates and types combine with aerodynamic processes to determine dune and swale morphology established foredunes are classified into five morpho ecological types and the flow behaviour over two types is detailed a new model of foredune evolutionary paths at various possible time scales is presented blowout initiation dynamics and sediment transport and evolution is examined throughout the review the gaps in present understanding of dune processes and a range of ideas for new research possibilities are provided

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

map based methods for estimating glacier equilibrium line altitudes we examine the validity of two methods for estimating glacier equilib rium line altitudes elas from topographic maps the ela determined by contour inflection the kinematic ela andthe mean elevation of the glacier correlate extremely well with the ela determined from mass balance data observed ela however the range inglacierelevations above sea level is much larger thanthe variation in ela mak ing this correlation unhelpful the data were normalized and a reasonable correlation r 2 0 59 was found between observed and kinematic ela the average of the normal ized kinematic elas was consistently located down glacier fromthe observed ela con sistent withtheory thenormalized mean elevationoftheglacierexhibitedno correlation and suggests that the toe headwall altitude ratio is not a good approximation for the ela kinematic waves had no effect on the position of the kinematic ela therefore topographic maps of glacier surfaces can be used to infer the position of the ela and provide a method for estimating past elas from historic topographic maps

textural and compositional characterization of recent sediments along a paraglacial estuarine coastline maine usa abstract textural and mineralogical characteristics of bottom sediments collected from the lower kennebec river estuary maine and adjacent nearshore region were used to differentiate subtidal sedimentary environments five depositional environments defined on the basis of bottom morphology bathymetry and dominant sedimentary processes estuarine channel channel margin outer bar shoreface and offshore possess distinct sedimentological characteristics trends in textural characteristics of these environments and those along the adjacent barrier beach include 1 systematic decrease in mean grain size from the estuarine channel to the offshore facies 2 similarity between the outer bar and estuarine channel sands 3 increase in sediment sorting from the channel margin and offshore to shoreface facies and 4 fining of the low tide terrace beachface and berm samples away from the bar welding region the fine grained nature of the offshore facies is the result of deposition of suspended sediment delivered to the coast during large flood events whereas the coarse fraction is contributed through the attrition of carbonate tests of the local macrofauna results of compositional analyses reveal 1 a decrease in shell fragments from the estuarine channel 50 to the offshore

geochemical constraints on the provenance of surface sediments of radial sand ridges off the jiangsu coastal zone east china abstract the jiang harbor centered radial sand ranges rsrs off the jiangsu coast are the largest in the yellow sea however the provenance of the rsrs remains controversial in this study we compare major and trace element geochemistry together with grain size and main mineral composition in carbonate free sediments from rsrs and potential sources onshore and offshore rsr sediments have different grain size characteristics onshore rsr sediments have mean grain sizes of 2 tio 2 li and partly in cs zn and some high field strength elements y zr nb pb and th while depleted in other elements offshore rsr sediments are complicated in geochemical compositions some of them have very high contents of high field strength elements and others are similar to onshore rsr sediments onshore and offshore rsr sediments have different controlling factors of geochemical compositions onshore rsr sediments are influenced by clay size minerals whereas offshore sediments are controlled by heavy minerals the identification of zr nb and ti zr vs k rb shows that onshore and offshore rsrs seem to have similar sources their differences in grain size are a result of hydrodynamic sorting the identification of elemental ratios reveals that sources of rsr sediments are variable in space and time and the inputs of the chinese rivers especially the old yellow river and the yangtze river are still dominant but the effect of the korean field cannot be neglected our findings also demonstrate the potential of elemental ratios such as zr nb and k rb as tracer pairs for provenance of sediments in the yellow sea

response of the nordenskiold land spitsbergen glaciers grumantbreen habergbreen and dryadbreen to the climate warming after the little ice age

the influence of soil structure and stress history on the soil water characteristics of a compacted till the soil water characteristic defines the relationship between the soil suction and gravimetric water content w or the volumetric water content or the degree of saturation s theoretical and

episodic sedimentation how normal is average how rare is rare does it matter where repeated sharp changes of sedimentation are inescapable periodic cycles are commonly invoked to preserve uniform orderly variations from some supposed norm the sedimentary record rarely reflects such uniformity however as sedimentologists have gradually realized magnitude versus frequency of processes has received little attention in sedimentology recurrence interval recovery time and preservation potential are critical factors for evaluating their significance for the sedimentary record large magnitude processes which represent positive deviations from the norm and are rare on the human time scale must be significant over geologic time everyday processes may have obliterated much of the evidence the sedimentological importance of rare events is difficult to assess because the record of such events may be very subtle this is especially true if a deposit has been thoroughly bioturbated or if the record of an event is simply an erosional surface it has now become possible to evaluate quantitatively ancient episodic sedimentation using modern process rates as well as refined biostratigraphic and isotopic dating i predict that such evaluation will necessitate revision of our favorite depositional models which have become so important for exploration as well as for research modified journal abstract

holocene environments in the hawkesbury valley new south wales a comparison of terrestrial and marine records abstract rapid sedimentation of sands silts and muds associated with seaward prograding tidal delta and central basin deposits characterise the early holocene sediment infill of the hawkesbury river s estuary from about 6 ka bp fluvial muds and sands dominate the estuary and sedimentation rates are much reduced micro fossil records contained in sediments from the middle hawkesbury colo rivers region support the sedimentological lithostratigraphic interpretation of estuary development information from fossil diatoms indicates that for a period of about 300 years around 6 ka bp there was an increased marine influence in this part of the present estuary this may have resulted from the probable peak in the rate of relative sea level rise although there may also have been a contemporaneous increase in freshwater flow down the river pollen and charcoal records from mill creek downstream from the colo sequence show that sclerophyll forest occasionally with rainforest elements became more dominant from 8 ka bp in contrast the upper tidal casuarina glauca forest decreased in importance during the phases of sea level rise and the subsequent still stand together the palaeoenvironmental records show broad agreement in defining the patterns of regional environmental changes and linked phases of estuary development during the holocene differences in records appear to relate to local site factors and to the limitations in provenance persistence and resolving power of the data types the rapid accumulation rates provide an opportunity to investigate high magnitude but low frequency events in estuarine environments including floods and fire

sediment supply from shoreface to dunes linking sediment transport measurements and long term morphological evolution a significant problem in current coastal research is the understanding of linkages between morphological phenomena occurring on different temporal and spatial scales morphodynamic processes in the nearshore typically exhibit nonlinear behaviour and consequently phenomena which occur on short temporal event scales as e g observed during field experiments have generally been difficult to upscale to provide an understanding of the long term behaviour of the coast on the time scale of seasons or decades this paper documents a persistent onshore migration of nearshore bar features over a period of 3 decades using a set of cross shore profile surveys from a barrier on the danish north sea coast the observed behaviour is consistent with experimental data obtained during weeklong field campaigns when sediment transport and bar migration were found to be landward directed during high energy dissipative conditions hydrodynamic and sediment transport processes leading to onshore bar migration and eventually welding of the bars are documented to provide an explanation for the observed long term evolutionary trends in addition bar welding and the resulting intertidal bar formation represent an onshore sediment storage which is subsequently available for aeolian transport observations on aeolian sediment transport indicate that transport rates and sediment supply to the foredunes critically depend on the presence of dry sand sources as represented by well drained intertidal bars measurements of long term accretion rates in foredunes indicate that volumes deposited on the crest and lee slope of the dunes are in reasonable correspondence with volumes supplied to the subaerial beach through the process of bar welding hence the data suggest that a persistent onshore directed sediment supply occurs from the shoreface across the surf and intertidal zones and into the dunes of the investigated barrier

juxtaposed beach ridges and foredunes within a ridge plain wonga beach northeast australia abstract reports describing aeolian foredunes and wave derived beach ridges juxtaposed within a single coastal barrier complex are rare perhaps because morphological similarities make the two ridge types difficult to differentiate this study of an approximately 4500 year old sand ridge plain in northeast queensland australia using landform morphology sedimentology and luminescence chronology suggests that ridge plain development here has been interrupted along part of the sequence by localised alterations in coastal sedimentation a switch from coarse to fine grained sand supply along one part of the beach has caused the development of prograding foredunes in the northeastern sector of the sequence over the past 700 years contemporaneously coarser textured beach ridges have continued to form behind the remainder of the beach the result is a complex barrier where a single ridge plain contains both foredunes developed through high frequency low intensity events and beach ridges developed through high intensity low frequency events associated with intense tropical cyclones

transgressive and regressive stratigraphies of coastal sand barriers in southeast australia abstract in recent years attempts have been made in southeast australia to document the stratigraphic characteristics of coastal sand barriers two basic arrangements of facies are distinguished those associated with transgressive depositional sequences and those associated with regressive sequences transgressive sequences either are formed during the postglacial marine transgression or are related to receding or transgressive barriers at present sea level in the former case complex interfingering of nearshore washover and lagoonal facies are evident in many areas these facies underlie those associated with regressive sequences which have formed since sea level has reached its present position ca 6000 6500 yrs ago examples of regressive sequences associated with both prograded and stationary barrier types occur in southeast australia here the thickness of nearshore facies in particular is commonly greater than equivalent units beneath barriers on coasts of lower energy and for less steep inner shelf gradients in the northern hemisphere the interplay of various factors within embayments has led to the development of several barrier types such as prograded stationary receded and episodic dune with some sedimentary characteristics in common with similar types recognized in other parts of the world e g texas delaware the netherlands barriers formed as a result of migrating spits and tidal inlets are not common in southeast australia

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

holocene coastal evolution of the transition from transgressive to regressive barrier in southern brazil abstract in this study the evolution of a holocene coastal barrier was determined based on a basal transgressive unit followed by a regressive unit standard penetrating test vibrocore and ground penetrating radar profiles were used to acquire stratigraphic data sedimentological paleontological and geochronological analyses were performed to describe and interpret the sedimentary facies the base of the holocene record indicates the existence of pre transgression continental and coastal environments basal peat which resulted from the initial flooding of the antecedent topography pleistocene substrate due to rising sea levels during this period the continental environments were flooded by lagoon environments that occupied the landward displacement of the transgressive barrier which had channels that connected the lagoon and the ocean at this time the coastal barrier had a transgressive configuration indicated by its morphology and characterized by washover fans as the backbarrier accommodation space decreased due to the displacement of the barrier transgressive maximum the transition of the transgressive regressive record began at approximately 7 200 years bp restricting the overwash events and the dynamics of the inlets however before the highest level eustatic maximum of the postglacial marine transgression pmt was reached this transgressive barrier stopped its migration toward the continent causing an inversion of the depositional record which became a normal regression later at the end of the pmt sea levels began to fall causing a forced regression that persists to the present day

quantification of historical landscape change on the foreland of a receding polythermal glacier horbyebreen svalbard the assessment of multidecadal scale change in a polythermal glacial landsystem in the high arctic is facilitated by a quantitative approach that utilises time series of aerial photographs satellite images digital elevation models and field geomorphological mapping the resulting spatiotemporal analysis illustrates a transition from glacial to proglacial paraglacial conditions indicating that 1 the areal coverage of ice between the maximum lia extent and 2013 decreased from 29 35 to 16 07 km2 which is a reduction in the glacierized area in the catchment from 62 to 34 2 the ice volume loss in the proglacial area amounted to 214 9 3 million m3 which was attributed mostly to ablation of the glacier snout but to a lesser extent the degradation of ice cored landforms 3 the transition from areas formerly covered by glacier ice to ice cored moraines glacifluvial deposits and other landforms was the most intense in the period 1990 2013 4 two end member scenarios polythermal glacial landsystem domains evolve during glacier recession each one dictated by the volume of debris in englacial and supraglacial positions and include a subglacial surfaces limited englacial and supraglacial debris related to temperate basal ice and b ice cored lateral moraines and moraine mound complexes significant supraglacial debris accumulations related to marginal cold based ice an additional assemblage of geometric ridge networks discrete or linear englacial and supraglacial debris concentrations relates to crevasse and hydrofracture infill branching out from an esker complex and is indicative of either surging or later rapid release of pressurised meltwater from temperate to cold based parts of the former glacier snout

controls of local geology and cross shore longshore processes on embayed beach shoreline variability 10 shoreline variability along the 3 6 km long narrabeen beach embayment in se australia is 11 investigated over a 5 year period we apply the one line shoreline change model lx shore 12 which couples longshore and cross shore processes and can handle complex shoreline 13 planforms non erodible emerged headlands and submerged rocky features the model 14 skilfully reproduces the three dominant modes of shoreline variability which are by 15 decreasing order of variance cross shore migration rotation and a third mode possibly 16 related to breathing model results confirm previous observations that longshore processes 17 primarily contribute to the rotation and third modes on the timescales of months to seasons 18 while cross shore processes control the shoreline migration on shorter timescales from hours 19 storms to months additional simulations simplifying progressively the bathymetry show 20 how the inherent geology strongly modulates the spatial modes of shoreline variability the 21 offshore central rocky outcrop is found to limit the rotation in contrast the submerged rocky 22 platforms that extend from the headlands enhance the shoreline rotation mode and increase 23 alongshore variability of the cross shore migration mode owing to increased alongshore 24 variability in wave exposure offshore wave transformation across large scale submerged 25 rocky features and headland shape are therefore critical to contemporary shoreline dynamics 26 2

geomorphological effects of catastrophic flooding on a small subtropical estuary the mgeni estuary is situated on the east coast of south africa tidal salinity changes commonly extend 2 5 km upstream from the mouth the subtropical climatic regime causes seasonal flooding the geomorphological effects of which are increased by a steep river gradient a 120 150 year flood event during september 1987 with an estimated peak discharge of 10800 cumecs resulted in the erosion of 1 86 106 m3 of sediment from the estuary the normal high tide volume of the estuary 0 35 106 m3 increased to 1 85 106 m3 after the flood the post flood intertidal volume tidal prism of the estuary was 0 43 106 m3 compared to 0 19 106 m3 before the event the nature and extent of erosion in the estuary was controlled by the composition of the estuary banks and bed material gravel and sand substrates were preferentially eroded from the estuary bed before the cohesive bank materials were undercut in sections of the estuary mud and fine sand were deposited on overbank areas when the flood waned and a lag of coarse sand and gravel was produced on the estuary bed approximately 46 per cent of the bedload sediment supplied to the estuary since 1917 was retained in the estuary until the 1987 flood the remainder was transported through the system and into the indian ocean results show that catastrophic floods play an important role in sedimentation in small estuaries

recent high arctic glacial sediment redistribution a process perspective using airborne lidar abstract progressive glacier thinning retreat and mass loss in the high arctic is increasingly exposing forefield sediments to processes of mobilisation and redistribution in this paper we quantify forefield sediment redistribution at midtre lovenbreen svalbard using repeat light detection and ranging lidar surveys conducted in 2003 and 2005 in combination with field based observations average surface lowering of the forefield over the observation period identified from lidar surveys is 0 05 ma 1 and two primary areas of sediment reworking are identified active fluvial incision of proglacial streams by 2 m and lateral moraine downwasting of similar magnitude multivariate analysis of fluvial and climatological field data indicates that observed forefield sediment mobilisation is driven primarily by discharge forcing but with contributions from thermoerosive processes and stochastic autogenic sediment supply during the period of observation disparity between sediment loss in forefield fluvial systems as calculated from lidar data 3000 4000 103 kg and monitoring of fluvial sediment load 1600 3500 103 kg suggests the likely presence of significant quantities of buried ice beneath a thick debris mantle as evidenced by field observations relatively uniform lowering of the moraine crest identified from our repeat lidar surveys indicates thermoerosion of an ice core however simple debris layer thickness modelling indicates an increase in variation of debris layer thickness at lower elevations providing support for the assertion that moraine disintegration is driven by complex combinations of both thermal and mechanical processes this study demonstrates the viability of using lidar in conjunction with field monitoring to better understand sedimentary deglaciation dynamics and processes and also highlights the significance of forefield areas in controlling the sediment yield from deglaciating catchments

a synthesis and review of the geological evidence for palaeotsunamis along the coast of southeast australia the evidence issues and potential ways forward abstract in recent years the role of extreme events such as tsunamis and storms in shaping coastal evolution and change has been increasingly appreciated around the world tsunami geologists are increasingly recognising the signatures of palaeotsunamis almost everywhere they look and in many cases base their interpretations on similar evidence for quaternary tsunamis first identified in australia geological research suggests that the coast of south east australia and others worldwide may have been impacted by palaeotsunamis many times larger than the catastrophic 2004 indian ocean and 2011 t hoku events in australia the debate centres on the hypothesis that the coast of south east australia preserves evidence for repeated large magnitude quaternary tsunamis if independently validated this hypothesis has profound implications for risk despite the potential importance of this hypothesis no synthesis or comprehensive review of the proposed geological evidence and chronology exists as a result it is difficult to assess the evidence and to draw conclusions about the nature of the hazard and risk along the coast this synthesis details the spatial distribution of reported palaeotsunami deposits along the coast of new south wales south east australia and summarises the distribution of different types of sedimentary and erosional evidence the age range of reported palaeotsunami deposits is identified and mapped before discussing same age chronologically correlated deposits these data are then used to draw broad conclusions about the evidence and identify future research questions to aid in the testing of the hypothesis for repeated tsunami inundation we show that 60 sites are purported to contain evidence of tsunami inundation over 650 km of the south east australian coast with a spatial concentration south of sydney geomorphic evidence distinctly different to that used elsewhere in global palaeotsunami studies is reported at 54 sites with erosional features described as the most frequent indication of inundation proposed tsunami deposits are evident at 44 sites with the dominant deposit type being imbricated boulder stacks radiocarbon dating at 39 of the sites led to a proposition of nine events during the quaternary eight of which occurred during the holocene interestingly 18 sites have no chronological data associated with them alternative interpretations are offered at six type field sites purported to contain palaeotsunami evidence attention is drawn to the disjunct between historical and geological scales of tsunami inundation in the region in addition to the contrast between the scale of reported palaeotsunamis and the robust evidence of smaller events a synthesis of research into the nature of the evidence is offered including critiques of evidence type and mechanisms a critical review of the chronological data is also presented in addition to the recalibration and analysis of published radiocarbon data the paper concludes with an outline of research questions for further work on proposed palaeotsunami sites in australia as well as a statement about likely risk in south east australia it also advocates the need for caution when interpreting evidence for palaeotsunamis elsewhere around the world when those interpretations are based on signatures originally reported in south east australia

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

climatogenic north south asymmetry of local glaciers in spitsbergen and other parts of the arctic although world glacier inventory wgi data for 241 local glaciers 1 km 2 in area in svalbard show a mean aspect of 014 24 their mid altitudes are lowest for an aspect of 109 46 which is inconsistent further data are generated here for the altitude length and source aspect of 205 local glaciers 0 3 6 0 km long in the main area of local glaciation in svalbard nordenskiold land all four mountain blocks have mean glacier source aspects of 356 to 018 the overall mean is 011 8 mid altitudes are lowest at 042 21 predicted to be 53 m lower than on opposite aspects lowest altitudes are predicted at 009 to 030 averaging 157 m lower than on opposite aspects these results show that local land terminating glaciers around 78 n are affected more by north south radiation receipt contrasts than by wind effects consistent with the trend found across most other arctic regions it is concluded that although weaker than in mid latitudes contrasts due to slope climates are substantial even in arctic glaciers this is apparent only when small steep glaciers are inventoried wgi data are incomplete and users need to check the thresholds of coverage

resilient modulus of unsaturated subgrade soil experimental and theoretical investigations the resilient modulus mr of subgrade soil is an important stiffness parameter for analysing fatigue cracking in either the asphalt or concrete layer of a pavement although subgrade soil is often unsaturated and subject to seasonal variations of moisture content and hence suction in the field effects of soil suction on the resilient modulus are generally not accounted for in existing testing methods in this study mr values of a subgrade soil under various stress and suction conditions were investigated using a suction controlled cyclic triaxial apparatus to enhance the accuracy of measurements hall effect transducers were employed to monitor the local axial and radial deformation of each specimen it was found that mr increases with number of load applications when a soil contracts but decreases slightly when a soil dilates when suction increases the soil response tends to change from contractive to dilative due to suction induced dilatancy moreover the measured mr is highly dependent on the s

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

stratigraphy of the late quaternary barrier lagoon depositional systems along the coast of china abstract four sedimentary facies assemblages of barrier lagoon systems along the coast of china can be distinguished facies assemblage 1 is underlain by terrestrial layers and overlain by marine layers with marine influences increasing from the bottom of the sequence to the top this facies assemblage is formed during transgression and is called the transgressive facies assemblage facies assemblage 2 is underlain by marine layers and overlain by terrestrial layers with a decreasing tendency of marine influences from the bottom of the sequence to the top this facies assemblage is formed during regression and is called regressive facies assemblage facies assemblage 3 is both underlain and overlain by terrestrial layers this assemblage is formed when the coastline remains stationary and is referred to as stationary facies assemblage facies assemblage 4 is modified from the above assemblage and involves the overlying of barrier islands upon lagoonal sediments this type of facies assemblage is formed during local transgression and is caused by changing sediment supplies it is classified as locally transgressive facies assemblage transgressive facies assemblage occurs in the lower part of the postglacial strata in coastal and deltaic plains up to the boundary of maximum postglacial transgression regressive facies assemblage occurs in the upper part of holocene strata between the boundary of maximum postglacial transgression and the present coastal line stationary facies assemblage occurs in the narrow zone near the maximum transgressive limit the coast of china cuts across several tectonic subsidence and uplift belts more than 90 of the total riverine sediments discharge into the subsidence belts forming broad coastal plains and thick depositional strata in such areas favorable conditions exist for the development and preservation of various kinds of barrier lagoon systems in the uplift belts due to the poor sediment supplies stationary and locally transgressive facies assemblages tend to be developed the best sites for the development of barrier lagoon systems are in the transitional areas between uplift and subsidence belts

modelling resilient modulus seasonal variation of silty sand subgrade soils with matric suction control resilient modulus of unbound materials is an important parameter in the mechanistic design of pavements although unbound layers are frequently in a partially saturated state a total stress approa

statistical assessment of soil water characteristic curve models for geotechnical engineering a number of empirical equations have been proposed for the soil water characteristic curve a nonlinear least squares method was used to determine best fit parameters for several empirical equations that were best fit to 230 water content versus soil suction data sets in addition two proposed correction methods to accommodate high soil suctions up to 1 000 000 kpa were applied to the various soil water characteristic curve equations the data sets of water content versus soil suction were arranged into one of the usda soil classifications based on their relative amounts of sand silt and clay only eight soil classifications had sufficient data for later analysis the quality of fit for each model was compared using the akaike information criterion a series of conclusions were arrived at regarding i the relationship between two and three parameter equations ii the relationship between exponential and sigmoidal type equations and iii the value of correction factors for the high soil suction

barriers barrier platforms and spillover deposits in st george s bay newfoundland paraglacial sedimentation on the flanks of a deep coastal basin abstract st george s bay and adjacent coastal areas of southwest newfoundland contain thick sequences of late quaternary glaciogenic sediments and have been subject to relative sea level fluctuations over a rang of 70 m during the past 13 5 ka glaciogenic sediments have been mobilized by littoral processes to form two types of deposits these are 1 the prograded barrier beach and spit at stephenville and flat island respectively which are associated with large subaqueous sandy platforms and 2 a wedge of well stratified sand and gravel on the landward flank of the shallow sill which extends across st george s bay at an average depth of about 25 m the subaerial barriers and spits are composed of gravel beach ridges overlain locally by thin aeolian deposits with freshwater and salt marsh peats in swales these barriers developed during the last several thousand years as relative sea level approached its present position from an early postglacial minimum of approximately 25 m the prerequisite for beach ridge formation was the deposition of large sandy subaqueous platforms which appear on shallow seismic reflection records as clinoform wedges prograded into the deep basin of inner st george s bay the barrier platform at stephenville is constructed across a deep submarine valley the flat island barrier platform sits on the flank of a glacially overdeepened trough partly filled by glacial and postglacial sediments and envelops a delta formed during the early postglacial low stand of relative sea level the platform and barrier together constitute a thick coastal sequence coarsening up from sandy mud at the base to gravel at the top the wedge of well stratified coarse sediment up to 50 m thick situated on the landward flank of the shallow sill overlies older glaciogenic sediments and passes laterally into postglacial basin muds steep foreset reflections dipping 10 20 are evident on shallow seismic reflection records suggesting that the wedge was formed by spillover of sediment entrained by wave and current action into the relatively deep basins of the inner bay active gravel ripples testify to the continued mobility of coarse sediment on the sill the formation of the spillover deposits barriers and platforms demonstrates the potential for glacially overdeepened basins to host thick heterogeneous coarse grained coastal and inner shelf deposits

historical evolution of the columbia river littoral cell abstract this paper details the historical coastal evolution of the columbia river littoral cell in the pacific northwest of the united states geological data from a d 1700 and records leading up to the late 1800s provide insights to the natural system dynamics prior to significant human intervention most notably jetty construction between 1885 and 1917 all reliable surveys charts and aerial photos are used to quantify decadal scale changes at the three estuary entrances and four sub cells of the littoral cell shoreline bathymetric and topographic change over three historical intervals 1870s 1920s 1920s 1950s and 1950s 1990s are integrated to provide an understanding of sediment sharing relationships among the littoral cell components regional morphological change data are developed for alongshore segments of approximately 5 km enabling comparisons of shoreline change to upper shoreface and barrier volume change within common compartments the construction of entrance jetties at the columbia river 1885 1917 and grays harbor 1898 1916 has profoundly affected the evolution of the littoral cell and has accentuated the morphological coupling between the inlets ebb tidal deltas shorefaces and barriers the jetties induced erosion of the inlets and offshore migration of ebb tidal deltas the change in boundary conditions at the entrances enabled waves to rework the flanks of ebb tidal deltas and supply enormous quantities of sand to the adjacent coasts over several decades the initial sand pulses have been dispersed alongshore up to tens of kilometers from the estuary entrances winter waves and coastal currents produce net northward sediment transport across the shoreface while summer conditions tend to induce onshore sediment transport and accumulation of the upper shoreface and barriers at relatively high rates historical shoreline progradation rates since jetty construction are approximately double the late prehistoric rates between 1700 and the 1870s erosion rates of the mid to lower shoreface to the south of the jettied estuary entrances have typically been greater than the accumulation rates of the upper shoreface and barrier suggesting that the lower shoreface has been an important source of littoral sediments over decadal and longer time scales until recent decades sediment supply from the ebb tidal delta flanks and lower shoreface has largely masked the decline in columbia river sediment supply resulting from flow regulation and dredging disposal practices with the contemporary onset and expansion of coastal erosion adjacent to the jettied estuary entrances proper management of dredged sediment is imperative to mitigate the effects of a declining sediment budget

late quaternary depositional architecture of po and tevere river deltas italy and worldwide comparison with coeval deltaic successions abstract po and tevere rivers form two of the most important deltas of the whole mediterranean area detailed investigations have been carried out in the last decade beneath the present delta plains of these two river systems using borehole data correlation with the aid of radiocarbon dates and other dating methods pollens archaeology a detailed sequence stratigraphic framework has been constructed in both areas especially for the last glacial interglacial cycle regional subsidence combined with short term sea level fluctuations of relatively high amplitude played a fundamental role in creating subtracting accommodation during the long phase of falling sea level which followed the tyrrhenian substage 5e transgressive event a discontinuous record of this phase is present in the subsurface of the po plain whereas poor or no preservation has been detected in the tevere area progradational lowstand wedges accumulated during the last glacial maximum mostly in the central part of the basins far from the present deltas and are lacking in the study areas where a hiatal surface is invariably recorded below the transgressive deposits glacioeustasy exerted a major control on sedimentation in both areas during the latest pleistocene holocene sea level rise infilling of fluvial valleys and rapid landward migration of barrier lagoon systems in the context of wave dominated estuaries characterized the transgressive phase in both po and tevere systems in place drowning and transgressive submergence mechanisms of barrier migration were effective predominantly between 13 5 and 9 ka bp in contrast shoreface retreat was dominant in the late transgressive phase the maximum flooding surface mfs can be traced physically from continental to marine deposits and has similar characteristics in the po and tevere river systems being marked by peat layers or lagoonal deposits at landward locations and by distinctive lithological characteristics and micro and macrofossils assemblages basinwards above the mfs the early highstand systems tract records initially the filling of the lagoons followed by the rapid progradation of wave dominate delta systems and flanking strandplains autocyclic processes such as distributary channel avulsion delta lobe abandonment and local subsidence due to sediment compaction were the fundamental controlling factors on sedimentation during deposition of the hst the stratigraphic architecture of the post glacial po and tevere delta complexes closely resembles the basic facies successions documented from coeval deposits of wave dominated and wave influenced clastic coasts both locally within the mediterranean area and in other parts of the world our study emphasizes however some additional features and major differences with previously published depositional models including i the development of backstepping wave dominated estuaries during transgression ii consistent changes through time in the mechanism of barrier migration iii a later construction of the delta systems with respect to what traditionally considered

polythermal glacier hydrology a review 1 the manner by which meltwater drains through a glacier is critical to ice dynamics runoff characteristics and water quality however much of the contemporary knowledge relating to glacier hydrology has been based upon and conditioned by understanding gleaned from temperate valley glaciers globally a significant proportion of glaciers and ice sheets exhibit nontemperate thermal regimes the recent growing concern over the future response of polar glaciers and ice sheets to forecasts of a warming climate and lengthening summer melt season necessitates recognition of the hydrological processes in these nontemperate ice masses it is therefore timely to present an accessible review of the scientific progress in glacial hydrology where nontemperate conditions are dominant this review provides an appraisal of the glaciological literature from nontemperate glaciers examining supraglacial englacial and subglacial environments in sequence and their role in hydrological processes within glacierized catchments in particular the variability and complexity in glacier thermal regimes are discussed illustrating how a unified model of drainage architecture is likely to remain elusive due to structural controls on the presence of water cold ice near glacier surfaces may reduce meltwater flux into the glacier interior but observations suggest that the transient thermal layer of near surface ice holds a hydrological role as a depth limited aquifer englacial flowpaths may arise from the deep incision of supraglacial streams or the propagation of hydrofractures forms which are readily able to handle varied meltwater discharge or act as locations for water storage and result in spatially discrete delivery of water to the subglacial environment the influence of such drainage routes on seasonal meltwater release is explored with reference to summer season upwellings and winter icing formation moreover clear analogies emerge between nontemperate valley glacier and ice sheet hydrology the discussion of which indicates how persistent reassessment of our conceptualization of glacier drainage systems is required there is a clear emphasis that continued integrated endeavors focused on process glaciology at nontemperate glaciers are a scientific imperative to augmenting the existing body of research centered on ice mass hydrology

integrated approaches for predicting soil water characteristic curve and resilient modulus of compacted fine grained subgrade soils this paper combines a series of approaches for predicting the soil water characteristic curve swcc and the variation of the resilient modulus mr of compacted fine grained subgrade soils with moisture content which is the key information required in mechanistic pavement design methods the presented approaches for the swcc and mr are integrated as i they are developed following the same philosophy ii they require only the measurements of the suction and moisture content or mr at saturated and optimum moisture content conditions for prediction and iii the predicted swcc is used for predicting the mr moisture content relationship experimental studies have been performed on five fine grained subgrade soils that were collected from different regions in ontario canada to determine their mr at various external stress levels and post compaction moisture contents as well as their swccs after the mr tests experimental measurements are predicted using the integrated approaches and the empirical

sedimentation in the cliff bound microtidal mtamvuna estuary south africa abstract the mtamvuna estuary on the natal coast of south africa is located in a drowned river valley and is surrounded by cliffs it has a spring tidal prism of about 350 10 3 m 3 sedimentary environments in the estuary can be divided into upper and middle reaches and barrier associated sand bodies the estuary exhibits limited floodplain development and small intertidal areas the bedrock valley is presently infilled with sediment to about 90 of its capacity this may be attributed to low sediment yields from the predominantly mud yielding catchment lithologies the low fluvial bedload yield to the coast is reflected in the wholly transgressive barrier sands and lack of holocene sandy deposits on the coast and continental shelf a significant proportion of the sediment in the estuary is derived from adjacent cliffs barrier morphology reflects variations in fluvial and nearshore dynamics enhanced flood tidal currents and low river flow encourage flood tidal deposition in the estuary whereas increased river flows transport flood tidal delta sediments seaward episodic overwash events deposit sand in the back barrier area and promote barrier rollover the volume of sediment in the barrier associated sand bodies however appears to remain constant and the barrier maintains a dynamic equilibrium morphological responses to fluvial floods are dramatic but short lived and are restricted mainly to the barrier which may be completely eroded during floods eroded sediment is deposited offshore as an ephemeral delta but when the flood wanes wave action gradually reworks the delta sands onshore to reform the barrier which ultimately assumes its equilibrium position and morphology

mesoscale coastal behavior related to morphological self adjustment high energy events extratropical storms tsunamis and hurricanes sediment supply variability and sea level rise are regarded as major drivers of coastal geomorphic behavior in this paper we document a 170 yr record of cyclic coastal changes that occur independently of such external drivers in a geologically constrained situation with no external sediment input two end member morphological configurations attractors are identified between which the system alternates although neither configuration is stable the system as a whole exhibits century scale equilibrium our findings present a hitherto unreported form of decadal scale self adjustment in a coastal system that has occurred under a stable sea level with a consistent wave and tidal regime

use of the grain size distribution for estimation of the soil water characteristic curve the implementation of unsaturated soil mechanics into engineering practice is dependent to a large extent upon an ability to estimate unsaturated soil property functions the soil water characteristic curve swcc along with the saturated soil properties has proven to provide a satisfactory basis for estimating the permeability function and shear strength functions for an unsaturated soil the volume change functions have not been totally defined nor applied in geotechnical engineering the objective of this paper is to present a procedure for estimating the swcc from information on the grain size distribution and the volume mass properties of a soil swccs represent a continuous water content versus soil suction relationship the proposed method provides an approximate means of estimating the desorption curve corresponding to a soil initially slurried near the liquid limit the effects of stress history fabric confining pressure and hysteresis are not addressed a database of published data is use

morphosedimentary evolution of a delta sourced drift aligned sand barrier lagoon complex western bight of benin the coast of eastern ghana and togo is bounded by a major holocene sand barrier complex hinged on the volta delta to the west and subject to high rates of longshore sand drift 1 1 5 106 m3 yr in spite of its proximity to this major deltaic sediment source this barrier system shows marked longshore variations in progradation following the middle holocene eustatic stillstand it is a hybrid system in terms of internal facies composition and plan view morphology in that it has evolved from an essentially regressive to a stationary synonymous with cessation of progradation system both transgressive and barrier inlet facies have also developed through time and space these temporal and spatial changes in patterns of development reflect variations in longshore sand transport and deposition over the last 5000 years such variations have been controlled by sediment supply from the volta by antecedent topography by lagoonal and river drainage by sediment cell development and maturation and in the very recent past by anthropogenic perturbation barrier progradation in the western bight of benin diminished considerably or ceased probably as early as 3400 yr b p as a single major equilibrium drift aligned bight cell matured permitting transport of volta sand toward the rest of the eastern bight in benin and nigeria the eastward longshore supply from the volta has involved both direct inputs of upland derived sand by the volta river channel and reworking of nearshore deltaic deposits a recent reduction in direct fluvial supply exacerbated by the akosombo dam completed in 1961 has induced a wave of erosion of the downdrift delta mouth barrier and shoreface deposits to fulfil the strong drift requirements in togo construction of a deepwater port in 1967 has also affected the barrier system both of these changes have had considerable impacts on longshore sediment dynamics the most significant impact has been segmentation of the former unique sediment cell characterising the 400 km long bight of benin coast resulting in differential longshore erosion progradation or equilibrium these changes have also induced new patterns of barrier behaviour that include transgressive and regressive dynamics at various locations alongshore

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

morphology dynamics and internal stratification of some established foredunes in southeast australia abstract foredunes are shore parallel dunes formed by aeolian deposition within vegetation modern established foredunes are classified into five morphologic stages and the morphologies and processes of each is described stage 1 foredunes are well vegetated symmetric stable ridges characterised by stoss face and crest deposition stage 2 foredunes display minor erosional patches 75 90 vegetation cover and slight lateral variation in deposition and erosion stage 3 foredunes are hummocky have a 45 75 vegetation cover range and display various scales of blowouts concave stoss faces and steeper lee faces stage 4 foredunes are characterised by large scale erosional features such as blowouts sand sheets and high asymmetry stage 5 foredunes comprise poorly vegetated remnant knobs each stage is characterised by a set of erosional and depositional processes which produce generally distinctive sets of cross strata sedimentary structures within examples of each foredune stage are examined stage 1 and 2 foredunes are dominated by simple large scale convex continuous strata stage 3 and 4 foredunes display increasingly variable sets of cross strata and a greater degree of planar and trough cross stratification wave cut scarps blowout structures and very steep lee slope bedding may be preserved the internal sedimentary structures presented here form the basis of a facies model for foredunes

evolution of the barrier islands of southern long island new york three lines of evidence based on data from more than 400 boreholes and vibrocores have been used to reconstruct the evolution of the barrier islands during the holocene transgression in southern long island new york 1 the holocene transgressive stratigraphic sequence behind the present barriers 2 the stratigraphic patterns of the inner shelf and 3 the morphology of the now buried late pleistocene coastal features the extensive preservation of backbarrier sediments radiocarbon dated between 7000 and 8000 yr bp on the inner shelf of southern long island suggests that the barriers have not retreated by continuous shoreface erosion alone but have also undergone discontinuous retreat by in place drowning of barriers and stepwise retreat of the surf zone such stepwise retreat of the surf zone has prevented the backbarrier sediments from being reworked based on the presence of submerged barrier sand bodies in seismic records it is inferred that about 9000 years ago when the sea stood about 24 m below the present sea level a chain of barriers developed on the present shelf about 7 km offshore of the present barriers with continued sea level rise the 24 m barrier built upward until the sea reached about 15 m msl just prior to 7000 yr bp the barriers were then submerged by the rapidly rising sea and the surf zone shifted rapidly landward to a position about 2 km from the present shoreline the surf zone overstepped to the landward margin of the old lagoon which had become fixed at the steep seaward face of mid wisconsinan or sangamonian coastal barriers during the past 5000 or 6000 years the shoreface has retreated continuously by about 2 km evidence from southern long island and elsewhere in regions of coastal submergence indicates that rapid sea level rise and low sand supply seem to favour the stepwise retreat of barriers whereas slow rates of submergence and a greater supply of sand generally favour continuous shoreface retreat stationary upbuilding or seaward progradation of barriers may occur when supply of sand is great and or submergence is slowed or reversed morphologic highs on the pretransgression surface such as old barrier ridges tend to fix the migrating barrier shoreline during either continuous retreat or stepwise retreat of barriers

beach ridges definitions and significance abstract beach ridges frequent components of quaternary coastal plains and other coastal landforms have been cited as indicators of the positions of ancient seashores and associated sea levels numerous authors utilized the term beach ridge for active and relict usually wave built supratidal and or intertidal forms wind built ridges have been only occasionally included in the definition the term was applied also to submerged landward shifting eventually stranded bars a consistent redefinition of the term is highly desirable beach ridges should include all relict strandplain ridges whether dominated by wave swash built or by eolian lithosomes all active ridge like shore features regardless of dimensions morphology and origin are excluded because of the resistance of coarse clastic ridges to wave and wind erosion swash built gravel or coarse shell storm ridges may build several meters above the level of high tide swash built high berms even on pure sandy beaches exceed the highest tides during episodes of wind induced record water levels frequently but not always burying underlying low relief berm ridges of berm lithosomes sequences of relatively steep multiple foredunes are commonly named beach ridge plains the narrow subparallel relict foredunes that form these strandplains presently are designated as eolian beach ridges beach ridges thus are defined as relict semiparallel multiple wave and wind built landforms that originated in the inter and supratidal zones until separated from the shoreline by progradation sandy pebbly or shell enriched backshore berm ridges behind an active foreshore should not be considered beach ridges strandplain progradation is either continuous or with the inclusion of subtidal cat s eye ponds discontinuous contrary to claims transgressive cheniers do not represent true cheniers alone within their overall progradational context cheniers a special category of beach ridges bracketed by subtidal intertidal mudflats may be transgressive or regressive in character landward driven transgressive ridges should be designated beach ridges only after they are stabilized on intertidal flats when recognizable between clearly identifiable intertidal and overlying eolian intervals the horizontal interface between these lithosomes in beach ridges may help the reconstruction of ancient tide lake levels diagnostic sedimentary textures structures and fossils however often may be unavailable in the deposits along with various types of elevated terraces composed of raised marine deposits and certain coastal landforms of erosional origin that occur worldwide beach ridges of clearly proven wave built origin may also serve as indicators of ancient higher than present sea levels

the role of extreme floods in estuary coastal behaviour contrasts between river and tide dominated microtidal estuaries abstract contrasting modes of sedimentation and facies arrangement in tide and river dominated microtidal estuaries arise from the degree to which river or tidal discharge and sediment supply influences an estuary a distinct facies gradation exists in tide dominated systems from sandy barrier tidal delta associated environments at the coast through deep mud dominated middle reaches to fluvial sediment in the upper reaches in river dominated systems fluvial sediment extends to the barrier and flood tidal deltas are poorly developed or absent from the estuary a number of independent observations during extreme floods on the south african coast indicate that these types of estuary respond differently to extreme river floods and that the mode of response corresponds to estuary type tide dominated systems exhibit preferential erosion of noncohesive barrier and tidal delta sediments during river floods while the middle reaches remain little modified river dominated systems experience consistent erosion throughout their channel length during extreme floods the increased cohesion of riverine sediments and stabilisation of bars by vegetation in river dominated channels means that higher magnitude floods are necessary to effect significant morphological change barrier erosion including the tidal delta results in deposition of an ephemeral delta composed almost entirely of sands from these deposits in tide dominated estuaries in river dominated systems eroded channel sediments and material from the river catchment may augment barrier sediments in the ephemeral delta deposit post flood wave reworking of ephemeral delta sediments acts to restore barriers to pre flood morphology within a few years however in river dominated systems the additional sediment volume may produce significant coastal progradation that requires several years or decades to redistribute these different modes of flood response mediated by the nature of the estuary have implications for coastal behaviour at the time scale of months to several decades estuary coastal behaviour at river dominated estuaries may be influenced for several decades by post flood morphological adjustment tide dominated estuaries however respond more rapidly in reworking flood eroded sediment and are typically fully adjusted to modal wave and tidal conditions within a few months to a few years in addition the facies arrangement within the two estuary types renders tide dominated estuaries more responsive to minor floods while river dominated estuaries by virtue of more cohesive channel sediments require greater discharges to effect significant morphological change

benchmark of experimental techniques for measuring and controlling suction the paper presents a benchmarking study carried out within the mechanics of unsaturated soils for engineering muse network aimed at comparing different techniques for measurement and control of suction techniques tested by the eight mechanics of unsaturated soils for engineering research teams include axis translation pressure plate and suction controlled oedometer high capacity tensiometer and osmotic technique the soil used in the exercise was a mixture of uniform sand sodium bentonite active clay and kaolinite non active clay which were all commercially available samples were prepared by one team and distributed to all other teams they were normally consolidated from slurry under one dimensional conditions consolidometer to a given vertical stress the water retention characteristics of the initially saturated specimens were investigated along the main drying path specimens were de saturated by applying suction through the liquid phase when using an axis translation technique or o

shelf edge deltas and drowned barrier island complexes on the northwest florida outer continental shelf abstract a high resolution multibeam survey of the northwest florida shelf mapped six relict shelf edge deltas each with a drowned barrier island system developed on its south and southwestern rims the deltas appear to have formed during periods of sea level stasis that occurred between 58 000 and 28 000 years ago the barrier islands formed on the deltas during periods of slow regression during this same time interval large fields of asymmetric dunes are found on the delta surfaces as well as on the south and southwestern flanks of the deltas the asymmetry and orientation of the dunes suggest that a northward flowing current was sheared by the presence of the delta topography and as a result the upper layer of the flow continued to the north whereas the lower layer was steered by the topography the topographic steering accelerated the northward flow around the south and southwestern flanks with speeds adequate to form large dunes the flow slowed after rounding southwestern flank but accelerated again as it encountered the next delta flank to the north the age of the dune formation is unknown and no northward flowing geostrophic flow has been reported in the literature from this area

luminescence dating of holocene sedimentary deposits on romo a barrier island in the wadden sea denmark this study presents an optically stimulated luminescence osl based chronology for the evolution of the barrier island romo and related back barrier lagoon deposits in the danish wadden sea the chronology is constructed using 78 quartz osl ages obtained using a single aliquot regenerative dose sar protocol samples were retrieved from seven sediment cores each up to 25 m long taken from locations on the island and within the back barrier lagoon the reliability of the osl results is assessed using preheat plateaus thermal transfer tests and dose recovery measurements and by comparison with independent age control the osl ages compare favourably with three 14c age estimates and range between 220 20 and 15 800 1200 years romo appears to have developed as a progradational barrier system and the island appeared for the first time approximately 8000 years ago it then gradually expanded towards the west north and south as a result of an abundant sediment supply luminescence dating is concluded t

behaviour of beach profiles during accretion and erosion dominated periods beach profiles have been surveyed at monthly intervals between 1972 and 1988 at moruya on the south coast of new south wales australia four profile sites have been used as a data set to provide an understanding of changes to beach volume width and shape moruya beach represents a moderately high energy microtidal environment which responds in a dramatic way to major storm events such as those experienced in the mid 1970s this study distinguishes between profile characteristics associated with such a period erosion dominated or edp compared with periods when accretion dominated adp accompanied by foredune expansion in both height and width