wave energy distribution and morphological development in and around the shadow zone of an embayed beach abstract background the curved shoreline shape of embayed beaches is one of its most notable characteristics and can be described using the parabolic bay shape equation pbse wave diffraction in and around the shadow zone is often regarded as the primary forcing mechanism leading to the prominent curvature of the shoreline however wave climate variables wave direction directional spreading and wave height are shown to be influential in redistributing wave energy throughout the bay and in the shadow zone methods in this study a process based morphological model delft3d is used for hydrodynamic and morphodynamic simulations of a schematic embayed beach wave forcing conditions are systematically varied between a mixture of time invariant and time varying cases results the role of diffraction is shown to be dominant only when the wave conditions are both narrow banded 30 otherwise as little as 6 variation in wave direction within a 90 range can account for the shoreline curvature in and around the shadow zone conclusion the degree to which wave direction and directional spreading vary through time therefore has a large effect on the equilibrium orientation and shoreline planform of the bay

pollen record of the past 60 ka bp in the middle okinawa trough terrestrial provenance and reconstruction of the paleoenvironment abstract core dgks9602 931 cm in length was retrieved from the middle okinawa trough the age model was correlated with the adjacent core dgks9603 li et al 2001 for the upper part and to the standard specmap chronology down to 60 ka bp using marine oxygen isotope control points pollen analysis was carried out and seven pollen zones were identified the results showed that the pollen spectra in mis 3 were very different to mis 2 but comparable with the holocene the saccate pollen principally pinus predominated in most parts of the core except for the interval of the last glacial maximum lgm and the late mis 3 when artemisia and other herbs increased prominently the ratios of p a pinus artemisia and of pb nap pollen with bladders versus non arboreal pollen were used as a proxy for sea level change and for estimating distances from the coastline to the study site the provenance study using a modern analog technique based on the east asian modern pollen database and fossil pollen assemblages revealed that the pollen were derived from diverse source areas during different stages since 60 ka bp the pollen zones equivalent to mis 1 and 3 were characterized by uncertain and disparate areas of provenance and the surrounding continents including eastern mainland china korea and southern japan possibly made equivalent contributions which may be the result of enhanced pollen transport by the northwesterly wind however the lgm represented in core dgks9602 was distinguished by restricted sources from the exposed east china shelf where the vegetation was quite similar with the herb coverage in the present day north china plain the pollen assemblages sensitively reflected the coastline changes marked by transport patterns between fluvial runoff and northwesterly winds plus ocean currents some pollen changes and limits of pollen zones coincided with the timing of heinrich events implying that the rapid climate fluctuations during mis 3 and mis 2 may have partially resulted in the forest changes in eastern asia the pattern of relative abundance of subtropical and total arboreal taxa is consistent with that of 18 o from hulu cave implying monsoonal climatic control over vegetation change the estimated temperature mat by the means of pollen ratios for the lgm was 5 8 c lower than that in the changjiang river mouth today

wetland expansion on the continental shelf of the northern south china sea during deglacial sea level rise abstract to identify environmental causes for past changes in vegetation in subtropical east asia we present carbon isotope compositions of plant wax n alkanes and provide estimates of the c4 plant contribution across the past four glacial terminations and interglacials based on cores recovered from the northern south china sea our results show a comparable c4 plant contribution between the last glacial maximum lgm and the holocene an increase of the c4 plant contribution by 15 20 is found for terminations iv ii and i relative to subsequent interglacial peaks coeval with an expansion of cyperaceae and poaceae in contrast termination v reveals a lower c4 plant contribution than marine isotope stage mis 11c the data exhibit a long term trend with a stepwise increase of the c4 plant contribution across interglacials mis 11c 9e 7e and 1 we suggest that no substantial changes in humidity levels over glacial interglacial cycles occurred facilitating a similar c3 c4 plant ratio for the lgm and the holocene instead deglacial sea level rises caused an extensive development of floodplains and wetlands on the exposed continental shelf providing habitats for the spread of c4 sedges and grasses the progressive subsidence of chinese coastal areas and the broadening of the continental shelf over the late quaternary explains the nearly absence of c4 plant occurrence during termination v and a gradual increase of the c4 plant contribution across interglacial peaks taken together changes in coastal environments should be considered when interpreting marine based vegetation reconstructions from subtropical asia

morphometric classification of swell dominated embayed beaches abstract globally embayed beaches are common to hilly and mountainous coastlines they are typically characterised by two headlands that are a primary control on incident wave exposure and beach morphodynamics embayed beaches exist under a range of headland morphologies and degree of embaymentisation here we present a generalised embayment morphometric parameter e which classifies the geomorphological setting of embayed beaches based on the embayment indentation and area we apply this to 168 swell dominated embayed beaches from 6 regions using open access imagery the embayment morphometric parameter e was subjected to k means cluster analysis to identify 4 classes of embayed beaches with increasing e indicating greater headland influence and impact on incident wave exposure the classes range from 1 to 4 with increasing degree of embayment the most common is class 2 43 n 73 which represents embayed beaches that have moderate embayment indentation and headland influence there are clear trends in embayment geometry regardless of location wave climate or tidal regimes within the embayments there were 6 possible headland orientations types h1 h6 the most common 58 n 97 is when both headlands are orientated outwards from the beach h6 and may result in greater morphological beach response from less headland shadowing compared with headlands orientated inwards onto the beach h1 in summary we have developed a simple classification scheme for embayed beaches based on degree of indentation and headland orientation that can be applied to any embayed beach globally

rip spacing and persistence on an embayed beach 1 four years of daily time exposure images from an embayed beach were examined to study the spacing persistence and location preferences of rips in a natural rip channel system a total of 5271 rip channels was observed on 782 days occurrence statistics showed no evidence of the preferred location pattern associated with standing edge waves trapped in an embayed beach the histogram of rip spacing the primary diagnostic observable for most models was well modeled by a lognormal distribution mean spacing of 178 m however spacings were highly longshore variable time mean of the standard deviation longshore mean of rip spacing was 39 so they are of questionable merit as a diagnostic variable storm driven resets to the longshore uniform condition required by most models occurred only four times per year on average making rip generation models relevant to only a small fraction of the system behavior rip spacings after the 15 observed reset events were uncorrelated with bar crest distance the lifetime of the 324 individual rip channel trajectories averaged 45 6 days rips were equally mobile in both longshore directions but the coefficient of variation of rip migration rates was large even for high migration rates the mean migration rate was well correlated to a proxy for the longshore current r2 of 0 78 thus there is no significant evidence that the formation spacing and migration of rip channels on this beach can be explained by currently existing simple models moreover the alongshore uniform initial conditions assumed by these models are rare on palm beach making the models generally inapplicable

problems of the quaternary on mountains of the sunda sahul region abstract two specific problems are identified in understanding the data on the quaternary of montane areas in the sunda sahul region these are 1 the upper montane rainforest according to palynological evidence appears to have been absent in the late pleistocene although it is well represented today 2 the estimates of temperature lowering in the late pleistocene are strikingly greater in the mountains than in the lowlands a single possible explanation for both problems is proposed it is argued that altitudinal zonation of vegetation is partly controlled by ultraviolet b light which is strikingly increased at high altitudes in the tropics this fact could account for both the above problems not only in the sunda sahul region but also in other tropical regions

geological control of beach morphodynamic state the concept of beach morphodynamic states has achieved widespread acceptance in the coastal geological literature since its inception in the mid 1980s and expansion in the 1990s much of the pioneering work was undertaken in australia under a range of environmental conditions in microtidal environments and a close empirical relationship between beach 3 dimensional morphology and the dean s parameter h b wst was established subsequently the relative tidal range parameter h b tr was extended to beaches of all tidal ranges in this paper observations are presented from 25 beaches around the north coast of ireland these beaches exist on an environmental gradient that encompasses marked tidal and wave energy variability micro to macrotidal and low to high wave energy each beach was visually categorised into one of several established beach states described in the literature on the basis of field observations for each beach the rtr and dean s parameter were calculated for the immediately antecedent period and used to predict the beach state using published relationships observed and predicted beach states were then compared comparison of observed and predicted beach states showed that while beaches with observed dissipative morphology typically matched the expected criteria most other beach states did not lack of agreement between predicted and observed beach states has been reported elsewhere and attributed to failings in the rtr and dean s parameter in addition this study identifies geological factors as important constraints on actual beach state in the majority of beaches studied inherited geological factors appear to be more important determinants of beach morphology than contemporary dynamics c 2005 elsevier b v all rights reserved

geologically constrained morphological variability and boundary effects on embayed beaches abstract headlands rock outcrops and engineering structures impact beach and nearshore dynamics of coastal embayments inducing boundary effects that constrain the lateral and vertical beach variability this study analyses morphological change in six embayed beaches with diverse levels of exposure to wave action and various degrees of geological control in the mesotidal coast of southwestern portugal the aim is to identify whether geological boundaries constrain the morphological behaviour of embayed beaches and assess whether their effects can be decoupled from datasets of morphological change topographic data obtained over a two year period on each of the six embayments were analysed using empirical orthogonal functions eof to decompose temporal and spatial variability in the datasets first and second mode eigenfunctions were explored using time variable linear correlation analysis with several nearshore parameters that include hydrodynamic variables sedimentary and geometric characteristics of each embayment in order to derive forcing response relationships our results demonstrate that natural geological boundaries constrain the morphological behaviour of embayed beaches producing conspicuous alongshore variability in all embayments localised responses induced by lateral and vertical boundary interference with beach and nearshore dynamics include beach rotation topographically controlled rip circulation and restrained profile fluctuation spatial decoupling in cross and longshore responses is accompanied by a temporal decoupling in response times both of which are slower in more constrained embayments from 1 day in exposed embayments to 1 week or more in the most sheltered ones normalised wave power was correlated at the 99 confidence level with the primary mode of morphological variability at most embayments which represent 67 to 94 of the variance in the datasets this correlation stresses the importance of combined parameterization of wave and tide forcing in process response relations between hydrodynamics and morphological change for mesotidal coastal environments lateral and vertical geological boundaries exert their effects fundamentally by restraining longshore sediment transport inducing cellular surf zone circulation and by impacting cross shore sediment transport it is postulated that decreasing sediment abundance and substrate depth intensify vertical boundary effects while higher indentation and wave obliquity enhance the effects of lateral boundaries

contrast in surface water δ18o distributions between the last glacial maximum and the holocene in the southern south china sea abstract published core data of planktonic foraminiferal 18o and alkenone sea surface temperature sst are used to investigate seawater 18o w distributions in the south china sea scs during the last glacial maximum lgm and the holocene the holocene w distributions show a pattern correlated to modern salinity distributions displaying an increasing trend from the south to the north however the lgm w distributions show a different pattern displaying increasing values from the central to the southern scs and the lgm holocene differences in w w corrected by ice volume effect though negative in values display decreasing amplitude toward the south both of which could suggest increasing salinity toward the south by conventional approach this is somewhat counter intuitive because enhanced freshening could be expected for the southern scs due to extra discharge from the river systems on the emerged sunda land during the lgm here we propose an alternative explanation to reconcile the lgm w and w distributions with the above expectation in the proposal changes in w salinity relationship i e lowering the w salinity slope due to significant runoff contributions to freshwater input and less 18o depleted precipitation during the lgm are deeply discussed to reasonably explain the abnormity in lgm w distributions

no aridity in sunda land during the last glaciation evidence from molecular isotopic stratigraphy of long chain n alkanes molecular distribution and stable carbon isotopic composition n 13 c of n alkanes determined in a sediment core 17962 from the southern south china sea scs show that no obvious change has taken place in vegetation on sunda land from the last glacial period to the beginning of the holocene a shift in the accumulation rate of longchain n alkanes c27 to c33 was recorded at a depth of about 620 cm probably indicative of precipitation enhancement related to winter monsoon the n 13 c values are within the range of 333 7 to 327 1x for c29 n alkanes and 333 9 to 328 4 for c31 n alkanes in the whole core sequence such an isotopic composition is characteristic of n alkanes biosynthesized mainly by plants utilizing the c3 photosynthetic pathway continuous development of c3 plants on sunda land and its surroundings evidences that the climate during the last glacial period in the southern scs was not drier than what it is today 2003 elsevier b v all rights reserved

glacial interglacial changes in equatorial pacific surface water structure during the plio pleistocene intensification of northern hemisphere glaciation the late pliocene early pleistocene intensification of northern hemisphere glaciation inhg represents the most recent major tipping point in earth s climate history in the equatorial pacific the inhg has been suggested to mark the transition from a warm pliocene climate state in which the pacific warm pool was greatly expanded relative to today giving rise to a surface ocean temperature field akin to modern el nino conditions to a climate state with strong upwelling in the east of the basin and stronger zonal temperature gradients here we examine this transition by presenting new high resolution 800 yr planktic foraminiferal mg ca and 18 18o based sea surface temperature sst and salinity sss based on 18o 18o residuals 18oivc sw 18oivc sw records from eastern equatorial pacific eep ocean drilling program site 849 spanning 2 75 2 4 ma our study interval contains the first large amplitude 1 in benthic 18 18o early pleistocene glacial interglacial cycles marine isotope stages 100 96 representing the culmination of inhg in this study we investigate west to east equatorial pacific sst and sss gradients we find that the zonal sst gradient increased by 1 5 c from 2 75 to 2 4 ma through eep cooling no glacial interglacial pattern is seen in this gradient on the other hand we document obliquity paced oscillations in the 18oivc sw 18oivc sw sss gradient we hypothesize that these oscillations originated from a response to a glacial southward and interglacial northward migration of the intertropical convergence zone over the eep

response of western pacific marginal seas to glacial cycles paleoceanographic and sedimentological features abstract this paper reviews the recent progress in late quaternary studies in five northwestern pacific marginal seas especially the south china sea as an example a series of marginal seas separate asia from the pacific ocean and significantly modify the material and energy flux linkage between land and sea during glacial cycles the sea level induced environmental signal was amplified in the marginal seas giving rise to drastic changes in areas and configurations of these seas and to reorganization of sea water circulation in basins since most of the western pacific marginal seas are influenced by monsoon circulation and some of these are located within the western pacific warm pool the glacial geographic changes have produced a profound impact on regional and global climate for example the decrease of sea area and sea surface temperature sst in the marginal seas was one of the factors responsible for the enhanced aridity of inland china during the glaciation glacial intensification of the winter monsoon and increased seasonality of sst in marginal seas might explain at least partly the apparent discrepancy between the tropical paleotemperature estimations based on terrestrial and open ocean records in this region as the western pacific marginal seas trap terrigenous material supplied by east asia the deep water sedimentation rates there can be one to two orders of magnitude higher than in the open ocean down slope sediment transport is more active when the sea level changes particularly during the deglaciation at least four types of carbonate cycles have been recognized in the western pacific marginal seas and each of those contains environmental signals from the surface and deep sea water as well as from the drainage basin

extreme erosion on high energy embayed beaches influence of megarips and storm grouping abstract megarips have long been recognised as an important yet poorly documented mechanism of beach erosion on high energy embayed beaches the persistence and cumulative effect of megarips during storm groups are described from three embayed beaches arrifana mt clerigo and amoreira exposed to high energy wave conditions in the mesotidal bedrock dominated southwestern coast of portugal morphological changes determined by topographic monitoring and supplemented by interpretation of digital imagery over two years revealed the development of storm induced megarips which exerted a major influence on beach erosion differences in megarip influence within and between beaches are related to embayment geometry and orientation which significantly influence the nearshore wave field rip location is topographically controlled being determined by alongshore variations in breaking wave height and obliquity along with interaction of wave driven circulation patterns and embayment nearshore topography moderate beach sand loss during individual storms was linked to the development of megarips with associated rip neck and feeder channels extreme erosion however occurred when megarips and feeder channels persisted during successive storms promoting continued erosion and seaward sediment export observations show that once initiated megarip channels persist for several months and continue to act as conduits for offshore sediment transport under non storm conditions the maintenance of such rip circulation systems driven by morphodynamic feedback reduces beach recovery ability until the rip neck and feeder channels are infilled

shallow structure and active tectonism of an offshore continental back arc spreading system the taupo volcanic zone new zealand the taupo volcanic zone tvz the predominant active volcano tectonic structure within the new zealand sub continent marks the zone of quaternary back arc spreading and calc alkaline volcanism associated with the convergence of the pacific and australian plates at the hikurangi plate boundary margin north island new zealand new bathymetric shallow seismic reflection magnetic anomaly and gloria data presented here accurately define for the first time the extent structure and tectonism of the poorly known offshore portion of the tvz these data show that nearly half of the entire ca 40 km wide tvz lies offshore extending northeast for some 150 km seaward to 36 45 s the southeastern and northwestern boundaries of the offshore tvz are significant tectonic and bathymetric features which comprise inward facing normal fault zone the white island and tauranga fault zones respectively three essentially parallel tectono morphological units are identified along the length of the offshore tvz they comprise from southeast to northwest a frontal non volcanic graben a volcanic ridge and a volcanic back arc graben the spatial position of these units with respect to the hikurangi subduction margin is not a simple arc and back arc relationship tectonism within the offshore tvz although pervasive increases from northwest to southeast so that the area of highest extension and subsidence of the non volcanic graben occurs in front of the volcanic ridge geophysical data also suggest the possible tectonic ablation of blocks of the forearc hinterland into the offshore tvz along its southeastern margin the southern havre trough and northern tvz are offset sinistrally by 45 50 km they overlap by 40 km and differ in orientation by ca 7 dextral displacement between these two extensional regimes is accomodated by a series of dextrally oblique and en echelon bookshelf faults the orientation of extensional structures within the offshore tvz is also dextrally oblique by 10 15 to the regional 030 trend of the bounding faults and agree with axes of maximum extension determined elsewhere from geodetic and seismological data

a pollen record of the last 37 ka in deep sea core 17940 from the northern slope of the south china sea this paper presents the palynological record of deep sea core 17940 from the south china sea 20 07 n 117 23 e water depth 1727 m this core is about 13 30 m long and covers the last 37 ka a total of 103 samples were counted at 10 cm intervals with a time resolution of ca 360 yr three pollen zones are recognized zone p1 14c age ca 37 0 15 0 ka b p 13 06 8 70 m is characterized by the expansion of montane conifers tsuga picea and abies and colonization by temperate grassland mainly artemisia on the exposed northern continental shelf as well as by frequent natural fires indicated by high values of charcoal concentrations this implies that the climate of this period was cool and dry frequent alternations of montane conifers and grassland dominated by artemisia indicate that oscillations of comparatively cool and humid conditions with temperate and dry conditions occurred according to the oxygen isotope data the period corresponds to stage 3 and the last glacial maximum climatic warming p2 a 8 70 7 23 m 15 0 11 3 ka b p associated with a rapid rise in sea level from ca 14 ka b p is inferred by expansion of tropical subtropical broad leaved forest with a replacement of grassland by mangroves mainly rhizophora and sonneratia this time interval may be assigned to the bolling allerod warming stage subsequently climatic cooling reflected by expansion of both montane conifers and upper montane rain forests mainly podocarpus and dacrydium during the period of ca 11 3 10 0 ka b p p2 b 7 23 6 6 m may be correlated with the younger dryas cold spell the similarity of pollen assemblages during the holocene and in the surface sediment from the northern south china sea implies that the vegetation and climate during the last 10 000 years was close to those of the present during the last 1400 years human activities are reflected in the sharp increase of dicranopteris fern spores

clay minerals sr nd isotopes and provenance of sediments in the northwestern south china sea abstract the clay mineralogy and sr nd isotopic composition of sediments collected in the northwestern south china sea scs were investigated to understand sediment provenance and changes in the scs since the late pleistocene our results show that the clay mineral assemblages of the surface sediments are characterized by high amounts of illite and smectite and low amounts of kaolinite and chlorite the 87sr 86sr ratios of the surface sediments vary from 0 709617 to 0 734416 and end values range from 11 6 to 8 3 the clay minerals and sr nd isotope records suggest that sediments in the northwestern scs are derived from multiple sources the sediments deposited in the eastern shelf offshore of hainan originate predominantly from hainan island and south china whereas sediments in the western shelf offshore of hainan are derived mainly from indochina and hainan island however sediment source and transport mechanisms in the northwestern slope of the scs are more complicated our results suggest that input from the west may be the major sediment source but regions in the east taiwan and luzon also contribute part of the terrigenous materials downcore variations of sr nd isotopic composition in core sediments show clear glacial interglacial fluctuations higher 87sr 86sr ratios occur during glacial period indicating that the input of terrigenous materials from old continental rocks becomes one of the important sediment sources during these periods the exposure of continental shelf and southward migration of the coastline during the glacial sea level lowstand led to an increase of terrigenous supply to the northwestern slope of the scs the paleo red river and indochina are also potentially important contributors

lithological and drainage network determinants of the character of drowned embayed coastlines the perception that coastal character reflects lithology via lithology s control on embayment size is tested by an examination of embayment sizes along a tectonically stable coastline to which ancient river systems drain the new south wales coast this coastline is comprised of four distinct geological provinces exhibiting a wide range of lithological and structural variation and is taken to be representative of physiographic settings controlling coastline configuration on a wide range of continental margin types our analysis shows that embayment size l the length of the embayment from headland to headland at sea level is related to the size of the river draining to the embayment catchment area a such that l 0 60 a 0 82 documentclass aastex usepackage amsbsy usepackage amsfonts usepackage amssymb usepackage bm usepackage mathrsfs usepackage pifont usepackage stmaryrd usepackage textcomp usepackage portland xspace usepackage amsmath amsxtra usepackage ot2 ot1 fontenc

applicability of parametric beach morphodynamic state classification on embayed beaches abstract use of parametric classification of beach morphodynamic state has been steadily increasing in coastal research despite identification of several shortcomings of their representativeness as elementary beach descriptors in this paper we analyse the parametric classification of beach morphodynamic state in a set of six embayed beaches in southwestern portugal exposed to diverse settings from high energy dissipative to intermediate to low energy intermediate to reflective conditions applicability of parametric approaches considered within the dimensionless space defined by dimensionless fall velocity and rtr relative tidal range according to averaged wave tide and sediment characteristics of beaches was assessed in association with a probabilistic analysis implemented through a bayesian network model that considered the full range of wave tide and sediment conditions at each site both parametric approaches were compared to field based beach state classification implemented using a novel hierarchical framework for beach state analysis the classification obtained within a probabilistic framework provided an innovative approach for analysis of beach state and mobility extending the insights on beach morphodynamic behaviour obtained from averaged environmental parameters reflective to lower intermediate beach conditions showed better agreement with parametric approaches while poor beach state differentiation was achieved for intermediate beach types limitations in the application of beach classification models result from i an inadequacy of existing beach state types in differentiating beaches particularly within the intermediate domain and for geologically controlled embayed beaches and ii shortcomings involved in the parametric approaches the beach state models disregard the major role of geological control in embayed beach morphodynamic behaviour in modulating beach shape and segmentation influencing sediment size and availability causing alongshore variations in the wave field and creating topographically induced nearshore circulations existing beach state models are unable to adequately represent the widely variable conditions observed in embayed beaches

relative sea levels and coastal sedimentation in southeast australia in the holocene abstract in recent years australian studies of relative sea level change have shown reasonable consistency on the termination date of the postglacial marine transgression at c 6 500 14c years bp the following stillstand period has been characterized in some regions by a slight falling trend from a high stand or in other areas by a level not easily distinguished from the present the latter situation occurs on the embayed coast of new south wales here studies of depositional environments and sequences within bed rock embayments have linked the holocene sea level history to patterns of sedimentation on the inner shelf in bay barriers and in estuaries deposition of quartz rich sand in shoreface flood tidal delta and backbarrier environments occurred during the marine transgre sion and the subsequent stillstand shell fragments from these deposits have been radiocarbon dated shoreline displacement continues to the present day partly in response to changes in availability of sand in the shoreface zone and partly in response to variations in regional storminess patterns a nd the great shroud of the sea rolled on as it rolled five thousand years ago herman melville moby dick

role of wave forcing storms and nao in outer bar dynamics on a high energy macro tidal beach abstract outer sand bar dynamics on a high energy macro tidal beach were investigated using long term multi year field datasets of intertidal morphology and offshore bathymetry utilising a 15 year time series of argus video images five distinct outer bar types were identified mega rip longshore crescentic crescentic attached and welded the most common classification was crescentic attached with the outer bar oscillations being out of phase with the inner bar oscillations as would be expected for the shore normal wave approach at this site the outer bar had a typical amplitude of 0 5 1 m and a longshore wavelength of 600 m changes in outer bar morphology were related to measured and modelled nearshore wave data however the outer bar morphology changed over a much longer timescale monthly to annual than the daily to weekly variations in wave height and period an extended duration of energetic wave action was required to bring about an upstate bar transition to the longshore or mega rip state where the bar then remained arrested for a significant amount of time requiring several months of low wave conditions to induce a down state transition through crescentic to welded this slow morphological response is explained by extended relaxation times attributed to the large tidal range at the study site where the outer bar morphology is only active for part of the tidal cycle several hours around low tide the configuration and position of the outer bar were related the more upstate downstate bar types being associated with a more offshore onshore bar position the detrended outer bar position was significantly related to a forcing term based on wave power and disequilibrium of the dimensionless fall velocity with offshore onshore bar migration occurring when wave conditions were more less energetic that the antecedent conditions the upstate end member longshore or mega rip was attained sometime during the winter months for 14 out of the 16 years of monitoring the outer bar remained attached to the low tide shoreline over the winter 2005 2006 and 2010 2011 these two winters with incomplete upstate cycles were characterised by the lowest winter wave conditions and negative winter north atlantic oscillation nao indices suggesting that the winter nao is correlated with both beach state and nearshore bar configuration

neural network modelling of planform geometry of headland bay beaches abstract the shoreline of beaches in the lee of coastal salients or man made structures usually known as headland bay beaches has a distinctive curvature wave fronts curve as a result of wave diffraction at the headland and in turn cause the shoreline to bend the ensuing curved planform is of great interest both as a peculiar landform and in the context of engineering projects in which it is necessary to predict how a coastal structure will affect the sandy shoreline in its lee a number of empirical models have been put forward each based on a specific equation a novel approach based on the application of artificial neural networks is presented in this work unlike the conventional method no particular equation of the planform is embedded in the model instead it is the model itself that learns about the problem from a series of examples of headland bay beaches the training set and thereafter applies this self acquired knowledge to other cases the test set for validation twenty three headland bay beaches from around the world were selected of which sixteen and seven make up the training and test sets respectively as there is no well developed theory for deciding upon the most convenient neural network architecture to deal with a particular data set an experimental study was conducted in which ten different architectures with one and two hidden neuron layers and five training algorithms 50 different options combining network architecture and training algorithm were compared each of these options was implemented trained and tested in order to find the best performing approach for modelling the planform of headland bay beaches finally the selected neural network model was compared with a state of the art planform model and was shown to outperform it

rip current type spacing and persistence narrabeen beach australia abstract long term daily rip observations on narrabeen beach australia were made together with daily measurements of wave height period direction surf zone width and beach state a total of 3513 rips were observed on 270 days over a 19 month period results show that rips accompany moderate to high waves and are associated with intermediate beach types rip spacing follows wave conditions increasing in spacing size and intensity as waves rise and conversely as they fall rips are a function of both the prevailing and antecedent wave conditions and the rate and direction of change in wave conditions rips are classified into three types erosion mega and accretion erosion rips are initiated by rising seas in the transverse bar and rip and higher beach states they accompany general beach erosion they are widely spaced narrabeen ys 300 500 m 100 200 m increasing in size and intensity with the waves until the fully dissipative ripless state is reached they are both temporally and spatially highly variable persisting in one location for only hours to a day or so except where topographically controlled they are a major mechanism for the seaward transport of sediment and under extreme conditions may extend over a kilometer seaward of the breaker zone mega rips are large scale 1 km topographically controlled erosion rips that persist when nearshore and or embayment topography prevents the development of the fully dissipative state by inducing wave refraction and persist longshore gradients in surf zone dynamics that in turn drive the rip circulation accretion rips prevail during stable or falling wave conditions usually following erosion rip formation they are associated with general beach accretion are more closely spaced narrabeen ys 170 250 m 100 m less intense and become increasingly topographically arrested by crescentic bars and rhythmic bar beach morphology of the longshore bar trough rhythmic bar and beach and transverse bar and rip beach states they are relatively stable both spatially and temporally and may persist in one location for days to weeks if wave conditions remain favorable they are fair weather rips which may disappear by infilling in the low tide terrace beach state or be destroyed by rising seas rips generally are absent from the reflective low tide terrace and fully dissipative beach states

persistence of storm induced morphology on a modal low energy beach a case study from nw iberian peninsula abstract the morphology of low energy beaches is inherited from high energy events showing a non equilibrium state with the prevailing conditions an example of a sheltered low energy beach rodas beach nw iberian peninsula is examined in this paper the evolution of six beach profiles was analysed during three years in order to investigate the response of this beach under fair weather and storm conditions the beach presented significant morphological differences alongshore due to its geographical location with respect to the wave approach these differences determined the sediment transfer pattern longshore or cross shore sediment transport from the emerged beach towards the adjacent inner shoreface zone significant morphological changes at each profile seem to be related to the incidence of sea waves along the beach superimposed on persistent swell during winter morphological changes were recorded under high energy storms during winter whereas the recovery to prestorm conditions occurred under prevailing fair weather conditions during summer the traditional beach classification parameter relative tidal range rtr which takes into account the effect of the tide range was found unsuitable to properly classify such a mesotidal low energy beach therefore a new parameter the relative tidal range maximum rtrmax was introduced which is a modification of the commonly used rtr rtrmax uses the highest wave breaking height observed during high energy storm conditions instead of the modal wave breaking height by using this parameter the studied beach could be properly classified into the traditional beach classification models taking into account the tide range since low energy beaches generally show a morphology that is inherited from higher energy conditions than the prevailing conditions it is expected that the rtrmax will be applicable for the classification of other low energy sheltered beaches

classification of rocky headlands in california with relevance to littoral cell boundary delineation abstract despite extensive studies of hydrodynamics and sediment flux along beaches there is little information on the processes pathways and timing of water and sediment transport around rocky headlands in this study headlands along the california coast are classified to advance understanding of headland dynamics and littoral cell boundaries in support of improved coastal management decisions geomorphological parameters for 78 headlands were quantified from geological maps remote sensing imagery navigational charts and shoreline geospatial databases k means cluster analysis grouped the headlands into eight distinct classes based on headland perimeter bathymetric slope ratio and the headland apex angle wave data were used to investigate the potential for sediment transport around the headland types and determine the efficacy of the headland as a littoral cell boundary four classes of headland appear to function well as littoral cell boundaries with headland size e g perimeter or area and a marked change in nearshore bathymetry across the headland being relevant attributes about half of the traditional california littoral cell boundaries align with headland classes that are expected to perform poorly in blocking alongshore sediment transport calling into question these boundaries better definition of these littoral cell boundaries is important for regional sediment management decisions

palynology of eastern indonesian marine piston cores a late quaternary vegetational and climatic record for australasia abstract pollen analyses of late quaternary sediments from nine marine piston cores reveal a continuous vegetation and environmental record for eastern indonesia and northern australia on the island of halmahera a montane oak forest largely replaced the tropical lowland vegetation during the last glacial period while fern cover was strongly reduced during its maximum 18 000 yr b p climate was cooler and slightly drier than today around 10 000 yr b p mangrove vegetation expanded following the rising sea level in our western new guinea record at 14 000 yr b p climate grew warmer and slightly wetter until it stabilised around 10 000 yr b p at that time the mid to upper montane forests expanded to their full altitudinal range and fern cover increased while montane oak forest grassland and woodland areas had contracted in our marine pollen records during the last glacial the climate of northern australia was distinctly drier than today grassland vegetation with sedges increased considerably at 38 000 and 24 000 yr b p replacing eucalypt forest and culminating in a maximum grassland cover at the height of the last glaciation 18 000 yr b p the rapid sea level rise allowed the expansion of mangrove forests and salt bush marshes which had become established on the large tidal flats of the drowning sahul shelf around 12 000 yr b p one piston core g6 4 extends to 300 000 yr b p and shows that glacial periods are characterized by high pollen concentrations in marine sediments recording expanding grassland vegetation during interglacial woodland and fern cover increased while pollen concentrations in the sediments were low after 190 000 yr b p a more open vegetation suggests that conditions were in general much more arid than before repeated mangrove vegetation expansions suggest major rises in sea level at around 244 000 220 000 and 130 000 yr b p

new evidence from the south china sea for an abrupt termination of the last glacial period abrupt changes in climatic conditions have been seen at high latitudes in the north atlantic1 and the antarctic2 3 at 13 kyr bp it is important to determine whether this abrupt change was confined to high latitude regions or whether it was global here we present results demonstrating an abrupt change in the rate and character of sedimentation in the south china sea at the close of the last glacial period radiocarbon dating and its position in the oxygen isotope shift suggest that this change may be coincident with the changes found at high latitudes

a morphometric assessment and classification of coral reef spur and groove morphology spurs and grooves sags are a common and important feature of coral reef fore slopes worldwide however they are difficult to access and hence their morphodynamics and formation are poorly understood we use remote sensing with extensive ground truthing to measure sag morphometrics and environmental factors at 11 430 grooves across 17 reefs in the southern great barrier reef australia we revealed strong positive correlations between groove length orientation and wave exposure with longer more closely spaced grooves oriented easterly reflecting the dominant swell regime wave exposure was found to be the most important factor controlling sag distribution and morphology gradient of the upper reef slope was also an important limiting factor with sags less likely to develop in steeply sloping 5 areas we used a subset of the morphometric data 11 reefs to statistically define four classes of sag this classification scheme was tested on the remaining six reefs sags in the four classes differ in morphology groove substrate and coral cover these differences provide insights into sag formation mechanisms with implications to reef platform growth and evolution we hypothesize sag formation is dominated by coral growth processes at two classes and erosion processes at one class a fourth class may represent relic features formed earlier in the holocene transgression the classes are comparable with sags elsewhere suggesting the classification could be applied globally with the addition of new classes if necessary while further research is required we show remotely sensed sag morphometrics can provide useful insights into reef platform evolution

rip current types circulation and hazard abstract rip currents are narrow and concentrated seaward directed flows that extend from close to the shoreline through the surf zone and varying distances beyond rip currents are ubiquitous on wave exposed coasts each year they cause hundreds of drowning deaths and tens of thousands of rescues on beaches worldwide and are therefore the leading deadly hazard to recreational beach users the broad definition above masks considerable natural variability in terms of rip current occurrence in time and space flow characteristics and behaviour in particular surf zone rip currents have long been perceived as narrow flows extending well beyond the breakers flushing out the surf zone at a high rate exit flow circulation regime while more recent studies have shown that rip flow patterns can consist of quasi steady semi enclosed vortices retaining most of the floating material within the surf zone circulatory flow circulation regime building upon a growing body of rip current literature involving numerical modelling and theory together with emergence of dense lagrangian field measurements we develop a robust rip current type classification that provides a relevant framework to understand the primary morphological and hydrodynamic parameters controlling surf zone rip current occurrence and dynamics three broad categories of rip current types are described based on the dominant controlling forcing mechanism each category is further divided into two types owing to different physical driving mechanisms for a total of six fundamentally different rip current types hydrodynamically controlled 1 shear instability rips and 2 flash rips which are transient in both time and space and occur on alongshore uniform beaches bathymetrically controlled 3 channel rips and 4 focused rips which occur at relatively fixed locations and are driven by hydrodynamic processes forced by natural alongshore variability of the morphology in both the surf zone and inner shelf zone and boundary controlled 5 deflection rips and 6 shadow rips which flow against rigid lateral boundaries such as natural headlands or anthropogenic structures for each rip current type flow response to changes in hydrodynamic and morphologic forcing magnitude is examined in regard to velocity modulation and changes in circulation regime providing key force response relationships of rip currents we also demonstrate that in the real world rip currents form through a mixture of driving mechanisms and the discrete rip types defined in fact form key elements in a wide and complex spectrum of rip currents on natural beaches it is anticipated that this rip current type classification will serve as a resource for coastal scientists and non specialists with an interest in the rip current hazard and as a platform for future rip current studies finally we suggest some important future research directions highlighting the need for coastal and beach safety communities to collaborate in order to improve rip current education and awareness

post depositional alteration of humid tropical cave sediments micromorphological research in the great cave of niah sarawak borneo the post depositional alteration of cave sediments is of critical importance for the recognition identification and investigation of geoarchaeological and palaeoenvironmental evidence there have been relatively few studies of tropical cave sediments using micromorphology and this work represents one of the most detailed with 26 samples taken from deposits in the west mouth of the great cave of niah that cover the last 55 000 bp and contain the earliest known evidence for the remains of modern humans in southeast asia cave sediments situated in the humid tropics are subject to relatively high temperatures and moisture conditions that promote high rates of chemical alteration and geomorphic change this paper outlines those post depositional features that occurred in situ in the west mouth and include translocation and concentration bioturbation excrement bone alteration plant alteration clast alteration and guano decomposition it examines their implications for recognising past human activities e g fire altered materials the preservation of archaeological remains the nature of palaeoenvironments and of localised physical and bio geochemical processes

on the influence of wave directional spreading on the equilibrium planform of embayed beaches abstract equilibrium beach formulations are engineering tools for estimating a response of beaches in the long term they aim at defining the final orientation of a beach on a scale of years and thus they are used for evaluating the shoreline response due to human interference ports breakwaters protection works etc several equations can be found in the literature for obtaining the static equilibrium planform sep of headland bay beaches hbbs one such being the parabolic bay shape equation pbse the sep is strongly dependent on the location of the down coast control point po which is the downdrift limit from which the pbse is applicable the literature recommends the determination of the po point by means of the direction of the mean wave energy flux at the diffraction point however when this is applied to equilibrium embayed beaches in zones with a wide variability of wave climate directionality and or in cases where the diffraction point is located far from the equilibrium shoreline this approach is no longer valid and thus the resulting planform shape does not properly fit the sep for such conditions this paper investigates the methodology for locating the po point of the sep for such cases exploring the role of wave climate directional spreading employing 44 hbbs in spain and latin america it correlates the planform shape in the long term with the directional variability of the wave climate at the diffraction point additionally an extensive series of numerical simulations using a spectral wave model was carried out to model the combined effects of refraction diffraction in the lee of a breakwater defining the part affected by the coastal structure under different wave conditions the results clarify the importance of wave directional spreading in locating the po indicating that the wider the directional spreading the farther the po point on the shoreline moreover the farther the diffraction point from the coast the smaller the part of the beach affected by the coastal barrier a new formula has been derived to locate the down coast control point po of the parabolic part of the shoreline corresponding to the pbse as a function of the directional variance of the wave climate and the location of the diffraction point the model produced good results with r2 0 9117 and a rmse 1 8297 in estimating the location of the po point in various natural and man made beaches with different degrees of wave directionality

simulation of the last glacial maximum climate over east asia with a regional climate model nested in a general circulation model abstract the east asian climate at the last glacial maximum lgm 21 000 years b p has been simulated using a regional climate model regcm2 nested in an atmospheric general circulation model of the institute of atmospheric physics iap agcm boundary conditions for the lgm simulations are consistent with the paleoclimate modelling intercomparison project pmip the results show that the nested regional model reproduces well the colder lgm climates over east asia the simulated annual mean surface temperature is 2 c 4 c colder than the present over the east asian continent with the coldest anomaly of about 8 c in the vicinity of current coastal areas where land is exposed due to lowering sea level at the lgm the precipitation changes are complex with general features of drier conditions over eastern china and its neighborhood and wetter conditions over western china than the present compared with the driving iap agcm the regcm2 results display better agreement with geological reconstructions over east asia especially in the mideastern and southern china the simulated warming changes by the iap agcm disagree with cooling in paleodata whereas the regcm2 reproduces realistic cooler lgm climate thus the current work proves that the high resolution regcm2 can capture additional regional details in the lgm simulation produced by improved representation of topography and physics

pleistocene paleoceanography of the south china sea progress over the past 20 years article i nfo the south china sea scs has become one of the foci in paleoceanographic research and hydrocarbon explora tions over the last 20 years over the period at least 16 international cruises including odp ocean drilling pro gram leg 184 have investigated the scs and more than 2000 exploratory wells have been drilled the present paper attempts to synthesize progress in pleistocene paleoceanography because of the high depositional rates and favorable carbonate preservation the scs keeps valuable paleoceanographic archives for the low latitude pacific region which have helped to uncover potential ties between the low latitude oceanic biogeochemical evolution and step wise development of the boreal ice sheet it has been found that the 1 6 ma event marked a reorganization of the oceanic carbon reservoir associated with the restructuring of the southern and the tropical pacific ocean the mpt mid pleistocene transition and mbe mid brunhes event centered at 0 9 ma and 0 4 ma respectively were preluded by carbon isotope maxima 13 cmax iii and 13 cmax ii suggesting that major steps in the ice sheet development were preceded by significant changes in oceanic biogeochemistry the late pleistocene records have demonstrated the amplifying role of the scs in responding to glacial cycles as the amplitudes of sst and 18 ov ariations have been significantly amplified in the scs as compared with the open ocean at the same latitudes the amplification is ascribed to its semi enclosed morphology and the prevail ing monsoon climate the closure of the southern margin during glacial times led to stratification of the upper waters and specific faunal changes in the southern scs the seasonally reversing monsoon winds not only drive the surface circulation but also the biological production the n s gradient in oceanography and the sed iment transportdynamics such asthe asymmetric growth of the mekong river delta becauseof its distinguished position in the low latitudes between the largest continent and the largest ocean the scs provides important insight into the mechanism of environmental evolution with regards to ocean continent or high low latitude interactions

asynchronous marine terrestrial signals of the last deglacial warming in east asia associated with low and high latitude climate changes a high resolution multiproxy record including pollen foraminifera and alkenone paleothermometry obtained from a single core dg9603 from the okinawa trough east china sea ecs provided unambiguous evidence for asynchronous climate change between the land and ocean over the past 40 ka on land the deglacial stage was characterized by rapid warming as reflected by paleovegetation and it began ca 15 kabp consistent with the timing of the last deglacial warming in greenland however sea surface temperature estimates from foraminifera and alkenone paleothermometry increased around 20 19 kabp as in the western pacific warm pool wpwp sea surface temperatures in the okinawa trough were influenced mainly by heat transport from the tropical western pacific ocean by the kuroshio current but the epicontinental vegetation of the ecs was influenced by atmospheric circulation linked to the northern high latitude climate asynchronous terrestrial and marine signals of the last deglacial warming in east asia were thus clearly related to ocean currents and atmospheric circulation we argue that i early warming seawater of the wpwp driven by low latitude insolation and trade winds moved northward via the kuroshio current and triggered marine warming along the ecs around 20 19 kabp similar to that in the wpwp and ii an almost complete shutdown of the atlantic meridional overturning circulation ca 18 15 kabp was associated with cold heinrich stadial 1 and delayed terrestrial warming during the last deglacial warming until ca 15 kabp at northern high latitudes and hence in east asia terrestrial deglacial warming therefore lagged behind marine changes by ca 3 4 ka

low latitude hydro climatic changes during the plio pleistocene evidence from high resolution alkane records in the southern south china sea abstract high resolution records of long chain n alkane biomarkers from the southern south china sea reveal tightly response of n alkane distribution to hydro climate changes over the past 5 ma with increasing longer chain n c31 alkanes indicating a correlation with drier conditions and increasing shorter chain n c27 alkanes with wetter conditions the variations of the c31 c27 ratio or the alkane chain length index imply humid conditions before 2 9 ma progressively reduced moisture since then and to bigger fluctuations between wet and dry conditions since 1 2 ma this long term hydro climate trend is superimposed by glacial dry and interglacial wet patterns over the plio pleistocene glacial cycles combined with other proxy records our results indicate that precipitation over the tropical asia pacific strengthened before the onset of the northern hemisphere glaciation and the mid pleistocene climate transition at about 1 2 ma these dramatic humidity changes over major climate transitions imply a crucial role of tropical hydrology dynamics on global climate change in the late cenozoic

modelling of embayed beach equilibrium planform and rotation signal abstract embayed beaches are highly attractive sandy beaches bounded laterally by rigid boundaries which deeply affect equilibrium beach planform and shoreline dynamics we use lx shore a state of the art shoreline change model coupled with a spectral wave model to address embayed beach shoreline dynamics driven by longshore sediment transport processes the model is applied to different idealized embayed beach configurations including variations in headland lengths the model simulates a large range of equilibrium embayed beach planforms and associated spatial and temporal modes of shoreline variability for short headlands enabling occasional headland sand bypassing both embayed beach curvature and maximum erosion at the upwave side of the embayment increases with increasing headland length beach curvature also increases with increasing headland length for headlands long enough to prevent any headland sand bypassing in contrast at the same time embayed beach becomes increasingly curved and symmetric with maximum localised erosion within the embayment decreasing in intensity when there is no headland sand bypassing rotation signal decreases in amplitude and becomes increasingly symmetric with increasing headland length the modal time invariant directional spreading of incident waves is critical to embayed beach behaviour with the envelope and variance of cross shore shoreline change and time averaged shoreline curvature all increasing with decreasing modal directional spreading embayed beach rotation characteristic timescale increases with increasing embayed beach length while the narrower the embayment the smaller the cross shore amplitude of shoreline variability our simulations provide new insight into the influence of embayment characteristics and incident wave conditions on equilibrium planform and shoreline dynamics of embayed beaches this work also implies that the degree of potential headland sand bypassing should be taken into account for modelling of beach rotational dynamics and embayed beach dynamic planform configuration

new insights into embayed beach rotation the importance of wave exposure and cross shore processes although embayed beach rotation has been viewed and modeled as an alongshore sediment transport process acting on a uniform beach profile recent research suggests a more complex response whereby alongshore variability in cross shore sediment fluxes may be more significant this study utilizes 5 years of fully three dimensional beach surveys at narrabeen collaroy beach se australia to quantify the control of alongshore nonuniform wave exposure and cross shore processes on embayed beach rotation empirical orthogonal function analysis of the alongshore variability in subaerial beach volume width and berm slope confirms that the dominant mode of subaerial beach variability is an onshore offshore sediment exchange that is strongly controlled r 0 8 by the alongshore gradient in breaker wave height and coincides with a uniform flattening steepening of the berm slope a secondary rotation like signal is observed in both the subaerial beach volume width data and significantly the berm slope this inverse flattening steepening of the berm slope between beach extremities is most likely a proxy for differing cross shore processes within the surf zone between the exposed and sheltered ends of the embayment particularly with regards to dissipation of storm wave energy by offshore sandbars and beach recovery following storms analysis of the corresponding wave data reveals two distinct time scales of wave forcing characteristic of short term erosion and longer term recovery processes a new conceptual model is presented of three differing modes of embayed beach rotation with the newly identified beach rotation mode controlled by offshore sandbars considered of particular importance at embayments where headland sheltering of oblique waves is pronounced

planview geometry and morphological characteristics of pocket beaches on the catalan coast spain abstract coastal planform studies are a relevant initial stage before launching detailed dynamic field experiments the aim of this study is to define the planform characteristics of 72 catalan pocket beaches natural and man made and to determine their sheltering effect embaymentization and their status of equilibrium planform measurements were performed on sigpac 1 5000 orthophoto sets and wave climate was provided by puertos del estado wana model planform parameters were applied and coastal planview indexes were determined the study shows that the catalan pocket beaches display a wide range of indentation suggesting that no single structural tectonic or morphological control dominates their planform the man made pocket beaches typically display indentations which are smaller than those shown by natural pocket beaches headland spacing and beach area are positively correlated the more indented bays are the shorter their beaches become low indented pocket beaches are the widest and the longest ones deep indentation contributes towards beach protection and energy dissipation which counteracts rip efficiency and inhibits the formation of mega rips pocket beaches often show gradual and moderate alongshore changes in texture and beach morphology one third of the catalan pocket beaches are sediment starved i e 60 and more of their embayed shorelines are deprived of beach sediments examination of the status of equilibrium demonstrates that most of the catalan pocket beaches are in an unstable mode with indentation ratios that are unrelated to the wave obliquity

morphodynamic characteristics and classification of beaches in england and wales abstract the use of beach classification models has become widespread in literature in recent years beach classification models that recognise distinct modal beach states in response to environmental conditions are most widely used these models were developed largely in high energy micro to meso tidal sandy environments and subsequent attention has focussed on extending their use into other beach environments here the applicability of these traditional beach classification models to the highly diverse coastline of england and wales was assessed through collection of detailed morphodynamic characteristics of 92 beaches yielding a comprehensive multi variate data set containing morphological sedimentological and hydrodynamic information the complex and diverse study region incorporates beach morphology covering the full spectrum from reflective to dissipative and non barred to multi barred cluster analysis supplemented by mds ordination resulted in the identification of 9 distinct beach types traditional morphodynamic indices and rtr were found to be effective in discriminating between beach groups providing some support for the beach state models derived using information from australian beaches it was found that absolute wave energy wave power is important as well in controlling beach type for intermediate beaches a wave energy flux p h 2 t value of 3 kw m 1 was found to differentiate between beaches with p 3 kw m 1 and without p 1 three dimensional bar rip morphology a key component controlling recreational beach hazard levels observations presented here inform a beach classification model to be used as the basis for a national beach risk assessment programme beach classification models based on environmental parameters are by necessity simplifications and should be used as tools for understanding morphodynamic systems rather than beach type prediction

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

last glacial pollen record from lanzhou northwestern china and possible forcing mechanisms for the mis 3 climate change in middle to east asia abstract the vegetation on the northeastern margin of the tibetan plateau is highly sensitive to climatic changes and thus represents a potentially interesting environmental archive pollen samples from the fanjiaping loess section in lanzhou on the western chinese loess plateau clp were analyzed in conjunction with osl dating the results indicate that pollen zone b 60 6 46 0 ka correlative to the early mis 3 had the greatest abundances of cupressaceae tsuga gramineae and cyperaceae of the entire section suggesting a warm phase during the last glacial period these pollen taxa decreased significantly in abundance in the zones c 46 0 39 0 ka and d 39 0 27 0 ka reflecting a substantial climate cooling from the middle mis 3 to mis 2 these results correlate with climate records from the south china sea the clp baikal lake north america north atlantic ocean and other regions and probably correspond with the decline of northern high latitude insolation and the increase of global ice volume from 50 to 20 ka in particular arboreal pollen fern spore and algae abundances declined sharply since 40 ka while shrub and herb pollen reached the highest abundances conifer pollen picea and abies abundance also rose markedly and increased up the section this implies significant climate deterioration and likely corresponded with substantial growth of the polar ice sheets since 40 ka the decreasing temperature caused by an insolation decline during the last glacial period probably reinforced the cooling effect in a snow ice albedo feedback which would result in less climate sensitivity to radiative forcing meanwhile vegetation decline in the northern hemisphere during the last glacial period and tundra development at high latitudes possibly caused additional cooling enhancing the growth of polar ice sheets since 40 ka the development of polar ice sheets increased the polar to equator temperature and pressure gradients strengthening the westerlies and supplying plenty of moisture to northwest china during 40 30 ka lake sediments developed widely on the tibetan plateau during 40 30 ka probably related to an increase in the seasonality of middle to low latitude insolation which caused an enhancement of glacier melting on the plateau

role of waves and tides on depth of closure and potential for headland bypassing abstract depth of closure is a fundamental concept used to define the seaward extent of a morphodynamically active shoreface at a particular temporal scale the estimation of this limit in relation to the depth in front of the bounding headlands along embayed coastlines allows questioning whether embayments often deemed closed sediment cells experience more headland bypassing than expected wave based parameterisations developed for microtidal beaches are most widely used to estimate closure depth however a re evaluation of the concept for shorefaces influenced by geological control presence of headlands and or bedrock and strong tidal currents is appropriate here we use the macrotidal embayed and high energy coastline of sw england to identify the active nearshore limits with a multi method approach that includes observations of shoreface morphology and sedimentology offshore inshore wave formulations and bed shear stress computations we identify the basal limit of significant i e 0 14 m morphological change depth of closure doc and a maximum depth of extreme bed activity and sediment transport depth of transport dot observations of doc correspond closely to the values predicted by existing formulations based on inshore wave conditions 10 15 m for the study area relative to mean low water spring water level in this case the computed dot represented by the upper plane bed transition attained under extreme conditions exceeds 30 m depth in the study area the significant implication is that even though many headlands appear sufficiently prominent to suggest a closed boundary between adjacent embayments significant wave and tide driven sediment transport is likely to occur beyond the headland base during extreme events especially at low water levels the maximum depth for significant sediment transport dot was computed across a broad wave current parameter space further highlighting that tidal currents can increase this closure depth estimate by 10 m along macrotidal coastlines representing a 30 increase compared to tideless settings this work illustrates the importance of tidal currents in depth of closure calculations and challenges the notion that embayed beaches are generally closed cells as headland bypassing may be more wide spread than commonly assumed along exposed coastlines globally

late quaternary paleoceanography of the south china sea glacial interglacial contrasts in an enclosed basin the sea surface paleotemperature of the south china sea scs is estimated quantitatively based on the quantitative analysis of planktonic foraminiferal faunas recovered from piston cores v36 06 3 v36 06 5 and so49 kl8 on the northern continental slope the results lead to a reconstruction of the history of paleocirculation patterns during the last 200 000 years the postglacial and interglacial transbasinal circulation pattern was replaced by a semienclosed basin flow pattern during glacial episodes lowered sea level transformed the scs into a semienclosed basin with the only passageway to the open ocean in its northeastern corner the east asian monsoon which governs circulation patterns in the scs both today and during the late quaternary created both clockwise summer and counterclockwise winter surface gyres during glacials the inflow of tropical surface water masses from both the pacific and indian oceans decreased or was completely cut off from this marginal sea causing a greater decrease in glacial sea surface temperature than in the open ocean of the same latitude inferred increased influence of pacific temperate waters and decreased influence of tropical subtropical waters are confirmed by changes in the planktonic foraminiferal assemblages glacial interglacial fluctuation in sea surface temperature sst 6 8 9 3 c for winter and 2 3 c for summer as well as the seasonality 4 6 c for postglacial and interglacials and 9 10 c for glacials are much greater than the adjacent open western pacific reflecting the amplification of the climatic signal in the marginal sea

a 135 000 year record of vegetational and climatic change from the bandung area west java indonesia sedimentological and palynological analyses of sediment cores from the intramontane bandung basin west java indonesia provide a first palaeoclimatic record for the indonesian region covering continuously the last 135 000 years our data on palaeosol development indicate anomalously dry conditions for the final part of the penultimate glacial period around 135 000 yr b p and very warm and humid interglacial conditions from 126 000 to 81 000 yr b p during the transition to the last glacial period around 81 000 yr b p freshwater swamp forest of the bandung plain was replaced by an open swamp vegetation dominated by grasses and sedges indicating a change to considerably drier conditions possibly related to reduced moisture uptake by the nw monsoon as a consequence of lower sea levels at the onset of glacial conditions a strong reduction in asplenium ferns from 81 000 to 74 000 yr b p suggests that drier conditions may also have occurred in the mountains of the bandung area while increased numbers indicate that from 74 000 to 47 000 yr b p it was slightly wetter again inferred depression of montane vegetation zones and reduced fern percentages suggests distinctly cooler and possibly drier climatic conditions prevailed in the bandung area from 47 000 to approximately 20 000 yr b p for the last glacial maximum 4 7 c lower temperatures are recorded

local scale proxy evidence for the presence of closed canopy forest in north western borneo in the late pleistocene bones of strategy i bats from the archaeological record of the great cave of niah sarawak abstract the limits of the distribution of closed canopy forest in southeast asia during the glacial cycles of the pleistocene are the subject of continuing debate in this context this paper reports the results of an analysis of a novel line of evidence as a local scale case study 22 dated assemblages of bat bones that were recovered from the archaeological sequences of the great cave of niah in sarawak malaysian borneo were examined by examination of the morphological characteristics of the distal articulation of the humerus seven families and nine genera were identified five species level attributions could be made these assemblages formed a time series of 14 chronological intervals 48 0 35 ky bp ky bp 103 calibrated years before present 1950 incorporating samples from the high glacial interval 26 18 ky bp and last glacial maximum 23 19 ky bp bones of bat taxa that are adapted to forage in the cluttered environments in the interior of closed canopy forest strategy i bats were employed as proxy evidence for the presence of closed canopy forested habitats in the vicinity bones of strategy i bats principally small hipposideros spp were identified in all examined assemblages and intervals in the time series statistical testing indicated no evidence of differences in the absolute frequency of distal humeri from strategy i bats in the pleistocene samples 48 11 8 ky bp or in the entire time series 48 0 35 ky bp and no significant linear trend was found in the time series to suggest an increase of the bones strategy i bat taxa with the onset of the holocene these findings suggest that closed canopy forest habitats have been a persistent component in the landscape around the great cave of niah since 48 ky bp a taphonomic hypothesis is proposed to explain the dichotomy between the findings of this study and the pollen record of the site

hydrographic variability in the northern south china sea over the past 45 000 years new insights based on temperature reconstructions by uk 37 and texh86 proxies from a marine sediment core md972146 abstract millennial scale climate variability was persistent feature for greenland ice core and north atlantic marine records during the marine isotope stage mis 3 studying high quality climatic archives outside of the greenland and north atlantic with precise constraint of absolute dating and high resolution sampling is a prerequisite to understand how the millennial scale changes well expressed in north hemisphere nh high latitudes had been propagated out to the other regions here we generated the surface and subsurface hydrography u k 37 and tex h 86 temperatures and terrestrial material input n alkanes records with precise ams 14 c dated control for the 45 ka from a core md972146 retrieved from the northern south china sea scs then we compared our records to the oxygen isotope record from a greenland ngrip ice core and the mean grain size record from a loess sequence at gulang china we found that the millennial scale oscillations of hydrolography and terrestrial material inputs records during the time since the last deglaciation and of 33 45 ka share similar patterns in timing and amplitude of the nh high latitude climate however we found that a non nh pattern of millennial scale oscillations for the late mis 3 20 33 ka of our hydrography and terrestrial material inputs records our studies imply that the changes of obliquity also may be important in determining the timing and amplitude of millennial scale east asian monsoon eam variability expressed in the northern scs hydrography and terrestrial material inputs

variations in organic matter composition in sediments from lake huguang maar huguangyan south china during the last 68 ka implications for environmental and climatic change abstract this study presents a continuous and long term palaeoenvironmental and palaeoclimatic record from a lacustrine sediment core lake huguang maar at the northern coast of the south china sea extending back to about 68 cal ka bp we provide a comprehensive ecosystem analysis from the opportunity to combine organic geochemical and palynological data several climatically induced changes to the flora and fauna have been recognised from 68 to 58 and 48 to 40 5 cal ka bp relatively depleted 13 c toc 31 3 to 25 0 and 13 c values of mid and long chain n alkanes 34 3 to 30 2 as well as high percentages of tropical pollen indicate a vegetation dominated by subtropical tropical forest c 3 plants an expansion of a mixed c 3 c 4 open grassland between 58 and 48 and particularly after 40 5 cal ka bp mirrors drier climatic conditions in conjunction with a lowering of atmospheric co 2 concentrations 13 c toc 24 1 to 16 8 and 13 c values of n alkyl lipids 28 9 to 24 1 are heavier higher percentages of non arboreal pollen were observed and the wood grass lignin index wgli from open pyrolysis py gc indicates a higher input of grass lignin abundant oxidised terrigenous particles that resulted from increased fire activity and or greater erosion rates are a further hint of enhanced dryness the clear drop in moisture availability suggests that this site is sensitive in fluctuations of the summer and winter monsoon activity in accordance with other proxy records in south east asia the response of the aquatic ecosystem is documented by an extremely large 13 c shift of algal derived botryococcenes from 35 4 to 6 2 which records a change towards a bicarbonate carbon source at low dissolved co 2 concentrations

vegetation on the sunda shelf south china sea during the last glacial maximum pollen and phytoliths from sediment cores 5018300 18302 and 18323 on the continental shelf of the southern south china sea are analyzed with special attention to reconstructing vegetation and climate changes on the sunda shelf during the last glacial maximum lgm the lgm pollen assemblages are characterized by high percentages of pollen from the lowland rain forests and lower montane rainforests suggesting that the exposed shelf was covered with humid vegetation a marshy vegetation with plants of sedges reeds bamboo etc developed in the valley along the north sunda river and around the marshes were distributed palms and a variety of ferns including tree ferns cyathea the climate during the lgm inferred from the vegetation was cooler than that at the present day but no significant decrease in humidity was recorded at least the change was not sufficient to prevent the growth of rainforest finally the observed fluctuations in percentage of mangrove pollen are considered as a sensitive indicator of coastline migrations on the sunda shelf c 2009 elsevier b v all rights reserved

understanding and predicting the temporal variability of sediment grain size characteristics on high energy beaches abstract despite representing a key parameter when modelling morphology or sediment transport surface sediments are often assumed homogenous with grain size temporally constant this contribution uses a 6 year data set of monthly sediment samples to quantify the observed variability in intertidal beach sands at four energetic macrotidal locations north cornwall uk changes in grain size and sorting were related to periods of high steepness storm waves promoting a relatively rapid coarsening and an improvement in sorting and low steepness swell waves a fining and a reduction in sorting these temporal changes in intertidal grain size were coherently linked to the disequilibrium in wave steepness with peak coarsening occurring when the instantaneous wave steepness conditions vastly exceeded a temporally evolving antecedent time series using this concept a simple model is proposed that provides skilful predictions of the unseen variability in sediment grain size average r2 0 86 p

a long vegetation history from lowland irian jaya indonesia abstract this paper reports the pollen analysis of a 10 m core from a mire at 780 m altitude and 2 s latitude on ultrabasic soils on a northern coastal range of new guinea the area is almost undisturbed by humans and the record is believed to cover about 60 000 yr b p the results show that montane forest grew around the site continously through the late pleistocene with a distinct increases in higher altitude taxa from 25 000 to 10 500 yr b p the time of glacial maxima elsewhere the invasion of the site by lower altitude forest which commenced at 10 500 yr b p was reversed after a few hundred years and was not finally completed until about 7000 yr b p the results show that vegetation in the region has been sensitive to climatic change the pleistocene ecology being consistent with a temperature change of about 3 4 c times of change agree with other tropical areas even though the site climate was probably affected by changing sea levels however the tropical forest demonstrates overall long term stability in which changes in dominance may reflect minor shifts in disturbance and tree longevity a distinctive record of fine charcoal occurs after 10 900 yr b p but not at any level prior to that time this shows that the forest was continously fire free for a very long time the charcoal is probably an indication of anthropogenic disturbance which may correlate with the spread of agricultural innovation in lowland new guinea an increase in secondary species after 7000 yr b p may be a result of minor anthropogenic activity or the result of warmer conditions and shorter tree life in the lower altitude forests

a hydroclimate regime shift around 270 ka in the western tropical pacific inferred from a late quaternary n alkane chain length record abstract the inert leaf wax deposited in deep sea sediment preserves clues of the past climate change in particular the n alkane distribution patterns characterized by the n alkane average chain length index acl provide useful information on the hydrological changes as longer chain alkanes are more frequently biosynthesized under relatively arid condition to prevent water loss our data from the western south china sea reveal the superimposition of a systematic regime shift in the regional mean precipitation at ca 420 270 ka on the glacial interglacial changes in the quaternary the dominance of shorter n alkane chain length between 420 ka and 270 ka is interpreted as overall wetter conditions during this period compared to the older or younger intervals a similar timing of hydrological regime shifts has also been observed in other paleoclimate records including major changes in productivity in the eastern pacific and pollen records from the western pacific we suggest that the changes in the regional mean hydroclimate states near 420 ka and 270 ka are most likely related to a regime change in the frequency and or intensity of the el nino southern oscillation with the overall wetter hydroclimate prior to 270 ka resulting in a more prevalent la nina like condition in the pacific

storm driven changes in rip channel patterns on an embayed beach this paper introduces a semi automatic computer algorithm designed to detect rip current channels in video imagery as a case study this method is applied to 3 3 years of video data from an embayed beach to demonstrate the link between antecedent surf zone morphology wave energy and up down transitions in beach state an objective measure of rip channel change was developed to define six significant rip reconfiguration events and relate these events to wave energy over the period of study no complete resets of the nearshore morphology occurred the analysis indicates that direct correlation of rip patterns with the instantaneous wave conditions is not a useful way to demonstrate how rips and waves interact the average wave energy over a period of ten days combined with storm duration were good indicators of rip channel change demonstrating that in general beach morphology responds with a time lag to changes in forcing rip channels with a short cross shore length and narrow alongshore spacing responded faster to changes in wave conditions than rips with a long cross shore length and wider alongshore spacing to force changes in the rip morphology longer rip channels required wave events of higher energy and or a longer duration offshore islands protect the beach under certain wave approach angles sometimes resulting in a dual width surf zone which was narrow at the sheltered end and wide at the exposed end of the beach the wider surf zone end was characterised by three dominant and persistent rip channels whereas the narrow surf zone section contained a number of smaller rips which evolved rapidly under wave forcing our observations demonstrate the importance of rip channel size in controlling the response time of nearshore morphology

dating of debris flow fan complexes from lantau island hong kong china the potential relationship between landslide activity and climate change five debris flow fan complexes bordering the coastal foothills of western lantau island hong kong have been the subject of a stratigraphic and dating study to explore the potential relationship between past periods of climate change and landslide activity luminescence osl ages from the fan complexes supported by a few calibrated radiocarbon 14c ages on duplicate samples suggest six main periods of accumulation 28 000 20 000 ka 14 500 10 500 ka 5800 5000 ka 4370 4230 ka 3560 3320 ka and 1350 1050 ka the younger periods 10 000 ka appear to be dominated by relatively thin 0 5 1 5 m units deposited mainly by debris flood events whereas the older periods are dominated by thicker 1 0 3 5 m units deposited by debris flow events we hypothesise that immediately prior to the last glacial maximum lgm i e 21 000 ka the climate was cool and dry upland areas were probably devoid of vegetation providing favourable conditions for sediment production in source areas these debris laden source areas are likely to have been mobilised during periodic rainstorm activity rapidly channelised over relatively short drainage courses and then deposited as thick sediment rich debris flow deposits along the coastal foothills during the early to middle holocene the climate was warmer and more humid pluvial conditions dominated forests occupied the upland source areas leading to possibly reduced sediment yields more frequent flash floods and deposition dominated by debris floods compared with recent studies on the weathering and erosion history of the pearl river delta our landslide age data are indicative of a potential link between increased landslide activity and intensification of the east asian monsoon during the early to middle holocene

nearshore hydrodynamics at pocket beaches with contrasting wave exposure in southern portugal abstract pocket beaches on rocky coasts with headlands that control hydro sedimentary processes are considered to be constrained sedimentary systems generally with limited sediment inputs pocket beaches face severe changes over time under worst case scenarios these changes can result in the loss of the beach causing waves to directly attack adjacent cliffs studies of nearshore hydrodynamics can help to understand such changes and optimise sediment nourishment procedures the present work contributes to the knowledge of hydrodynamic forcing mechanisms at pocket beaches by providing a comprehensive description of the nearshore circulation at two beaches with contrasting wave exposures two pocket beaches in southern portugal were studied by combining field measurements of waves and currents with numerical models stwave and bouss 2d the aim of this analysis was to evaluate nearshore hydrodynamics under different wave exposure forcing conditions e g variable wave heights directions and different tidal levels the results show that the beach circulation can rapidly shift from longshore to rip dominated depending on changes in both the offshore wave direction and tidal levels waves with higher obliquity for both low and moderate wave energy conditions tend to generate longshore circulation in all considered tidal stages while waves with lower obliquity tend to produce rip flow with higher velocity rip currents during low to intermediate tidal stages the results indicate that the location and intensity of rip currents strongly depend on geomorphological constraints that is the control exerted by shore platforms a larger morphological control is observed at mean sea level because most platforms are submerged exposed during high low tide and therefore exert less control on nearshore circulation

pollen distribution in hemipelagic surface sediments of the south china sea and its relation to modern vegetation distribution abstract this paper analyses the distribution of pollen in the surface sediments of the south china sea as recorded in 28 samples from the area 6 09 20 07 n and 112 05 119 45 e at water depths of 329 4307 m pollen concentrations range from 444 kgrains g dry wt on the lower part of the continental slope in the northeast to zero in the central basin below 4000 m water depth pollen distribution patterns in the concentration and percentage isopolls incorporating data from the literature reflect the routes and mechanisms of pollen transport pollen source areas and considerable systematic differences between north and south the northern scs is distinguished by very high concentrations due to the high production and effective long distance transport of pine pollen and fern spores the maximum of their concentration occurs in the north adjacent to the convergence of the bashi and taiwan straits rather than near the estuaries of big rivers and stretches as a saddle from ne to sw consistent with the direction of the ne winter monsoon and sea current this pattern implies that pine pollen and fern spores adapted to wind transport and water flotation come from the northeast through the straits borne on the winter monsoon and sea current forced by it their source areas should cover large regions probably including south and southeast china most pollen of tropical and subtropical broad leaved trees found in the northern part of the scs occur in low concentrations however these concentrations decrease uniformly offshore implying a fluvial discharge from nearby lowlands in south china in the southern part of the scs pollen of tropical and subtropical broad leaved trees predominate total pollen concentrations however are much lower only 1 10 of those of the northern part the greatest concentrations occur offshore north borneo and decrease toward deep water suggesting fluvial input from relatively local sources on the adjacent islands e g borneo

formation and fate of sedimentary depocentres on southeast asia s sunda shelf over the past sea level cycle and biogeographic implications abstract sea level variations are the major factor controlling sedimentation as well as the biogeographic patterns at continental margins over late quaternary times fluctuations on millennial time scales produce locally complex deposits in coasts and on shelves associated with short term influence on species development this article reviews the sedimentary and biogeographic history of the tropical siliciclastic sunda shelf as an end member of continental shelves regarding extreme width an enormous sediment supply and highest biodiversity in response to rapid sea level fluctuations we describe particular depositional segments as part of a genetic succession of zones from land to the deep sea based on literature data field observations and calculation of hydro isostatic adjustment effects on changing relative sea level these segments are characterized by individual sedimentary processes and deposits and by a specific potential for material storage and re mobilization long term regressive intervals led to overall sigmoidal promoting extremely thick and wide succeeding units in contrast rapid lateral shifts of defined depocentres over long distances took place in response to short term sea level fluctuations fully isolated small scale sediment bodies formed when sea level changed at exceptionally high rates as a result of the high availability of organic rich sediments mangrove and freshwater peats formed frequently over late quaternary times the appearance of thick massive and widespread peats is mainly linked to time intervals of a sea level rise at slow rates whilst organic matter appears much more dispersely in the sediments during episodes of rapidly changing sea level the preservation potential of the regressive units is generally high due to highest initial sediment supply stabilizing soil formation during exposure and rapid subsidence preservation of depositional elements from other periods is more exceptional and either restricted to local morphological depressions or to episodes of rapid sea level change besides complex channel incision an overall lowering of the sediment surface related to erosion as deep as 20 m or more over wide areas took place mainly during sea level lowering the final export of shelf material is documented by enormous mass wasting packages on the associated continental slope from a palaeogeographic perspective the rapid formation or disappearance of special habitat zones such as mangrove fringes and extended mud flats led to species establishment or truncation in distribution in addition the opening or closure of ocean passages as narrow bridges allowing limited species crossing or as fully colonized corridors had severe impact on eco fragmentation and the expansion or contraction of species independent of such particular conditions sea level changes have been too rapid over the past climatic cycle to allow full regeneration and mature development of coast related ecosystems

grain size distributions on high energy sandy beaches and their relation to wave dissipation grain size and sorting represent two key parameters when characterising sediments or modelling beach morphology and sediment transport traditionally an average value for grain size or sorting is often assumed for the entire area determined from only a few sediment samples ignoring any spatial or temporal variability in sediment characteristics this contribution uses a data set of physical surface sediment samples from 53 beach locations around the south west peninsula of the united kingdom in addition to bi monthly high spatial resolution mean 240 samples digital grain size surveys from a high energy oceanic sandy beach perranporth north cornwall systematic spatial variations in grain size and sorting were consistently observed in the seaward direction across the intertidal zone of sandy beaches with grain sizes coarsening and sorting improving by up to 51 7 and 64 3 respectively this variability was deterministically related to the time averaged antecedent adjusted energy dissipated by breaking waves with the observed maximum grain sizes and sorting values correlating with the location of peak wave energy dissipation r2 0 998 p 0 01 this article is protected by copyright all rights reserved

late quaternary vegetation and climate changes inferred from a pollen record of dongyuan lake in southern taiwan abstract a pollen record sampled from a valley basin in southern taiwan shows the environmental change specifically vegetation and climate that has occurred there since 22 000 cal yr bp in contrast to the subtropical evergreen forest found there today temperate broadleaved and conifer mixed forest occupied the basin between 22 000 and 16 000 cal yr bp which suggests that climate conditions were considerably cold during the last glacial maximum lgm and early deglacial period during the interval from 16 000 to 11 400 cal yr bp this basin was situated near an ecotone of two altitudinal vegetation zones i e a temperate conifer broadleaved mixed forest and a warm temperate evergreen forest which suggests the gradually warming climate conditions of the late glacial period the climate experienced further warming between 11 400 and 8200 cal yr bp as evidenced by the dominance of warm temperate evergreen forest elements subsequently the subtropical evergreen forest prevailed in the basin between 8200 and 4100 cal yr bp which reflects a considerably warmer mid holocene in addition tropical evergreen forest appeared in the area circa 6100 cal yr bp marking the holocene thermal optimum hto following that a warm temperate evergreen forest thrived between 4100 and 2100 cal yr bp finally a subtropical evergreen forest began its reemergence in the basin from 2100 cal yr bp and continues to grow there today from a comparison of these changes in vegetation we propose that 1 the annual mean temperature of the lgm was at least 7 c lower than today and 2 the hto was at least 2 c higher than present

on the significance of sea level variations and shelf paleo morphology in governing sedimentation in the southern south china sea during the last deglaciation abstract deglacial sedimentation on the outer sunda shelf the shelf margin and slope shows a close correlation with the stages of flooding of the emerged shelf it is mainly controlled by the relationship between shelf paleo physiography and changes in sea level and sediment supply based on the sedimentological and geochemical variability at five sites along a transect across the outer shelf and the continental slope covering the last 20 000 years four intervals of significant depositional changes are identified the first reorganization in the sedimentation regime which was established during sea level lowstand is associated with the drowning of the lower course of the north sunda river between 16 5 and 14 5 ka during and following the rapid rise in sea level at 14 5 14 ka sedimentation on the slope is characterized by an accelerated decrease in the supply of terrigenous material associated with the flooding of the middle part of the paleo valley this abrupt change in sedimentation is followed by a period of gradual decrease of terrigenous supply to the slope when the surrounding plains of the river valley were flooded 14 8 5 ka the final change occurred between ca 8 5 and 6 ka when the coastline reached its modern position and modern sedimentary patterns are established this change probably marks the end of reworking by transgression given the synchroneity of sedimentological changes along the transect across the sunda shelf and into the deep sea with the environmental shifts on the central shelf sedimentation on the margin and slope appears to be mainly controlled by the interrelationship of sea level shelf paleo physiography and sediment supply moreover the records display lateral changes through time associated with stages of the deglacial transgression which mask any potential sedimentological variability due to changes in precipitation vegetation or atmospheric circulation this fact cautions the interpretation of near shore sedimentary records as unequivocal recorders of local climate change e g se asian monsoon and highlights the need to include variations in shelf physiography and sea level in future paleoceanographic studies

pleistocene vegetation of the humid tropics of northeastern queensland australia abstract the humid tropics area of northeastern queensland has provided a substantial and detailed history of rainforest and rainforest savanna interactions from the pollen analysis of a number of sites on the volcanic atherton tableland through the latter part of the quaternary period a recent extension of the record to close to the base of the quaternary from examination of an offshore core provides a broad regional and temporal context for evaluation of the true significance of late quaternary changes it is apparent that the major sustained change in the vegetation of the region occurred relatively recently probably within the last 140 000 yr and that this change was time transgressive it involved the replacement of extensive moist rainforest by open eucalypt woodland and is considered to have been most likely caused by the burning activities of aboriginal people some aspects of the record from this region can contribute to the history of rainforest on a global scale but other features of it re inforce the unique nature of the development of australian vegetation patterns

extreme wave activity during 2013 2014 winter and morphological impacts along the atlantic coast of europe studies of coastal vulnerability due to climate change tend to focus on the consequences of sea level rise rather than the complex coastal responses resulting from changes to the extreme wave climate here we investigate the 2013 2014 winter wave conditions that severely impacted the atlantic coast of europe and demonstrate that this winter was the most energetic along most of the atlantic coast of europe since at least 1948 along exposed open coast sites extensive beach and dune erosion occurred due to offshore sediment transport more sheltered sites experienced less erosion and one of the sites even experienced accretion due to beach rotation induced by alongshore sediment transport storm wave conditions such as were encountered during the 2013 2014 winter have the potential to dramatically change the equilibrium state beach gradient coastal alignment and nearshore bar position of beaches along the atlantic coast of europe

late quaternary paleoceanography of the south china sea surface circulation and carbonate cycles paleoceanographic information from 34 sediment cores is summarized to investigate the glacial interglacial variations in sea surface circulation and late quaternary carbonate cycles in the south china sea judging from the distribution pattern of deposition rates the enormous terrigenous supply by rivers is responsible for the high rate of hemipelagic sedimentation which was even higher during glacial periods paleotemperature maps based on transfer function temperature estimates have revealed a e w gradient of sst for glacial summer and a s n gradient for glacial winter and this agrees well with the clockwise surface circulation in summer and counterclockwise in winter during glacials as shown by a preliminary computer modelling the high resolution paleotemperature curves of core v36 3 from the northern slope show an abrupt cooling event which may belong to the younger dryas carbonate percentage in sediments and preservation of foraminifers and pteropods are used to study the carbonate cycles in the marginal sea it turns out that two mechanisms are functioning there being a basin with large drainage areas vast amount of river borne terrigenous input dilutes carbonate and its intensification during glacial decreases the glacial cac03 being a basin connected with the pacific the fluctuations of lysocline ccd and acd in the scs are related to those in the pacific ocean and dissolution is strengthened at interglacial thus above the present ccd the dilution factor predominates and the atlantic cycles are produced below the present ccd the dissolution factor prevails resulting in the pacific pattern of carbonate cycles

surf zone flushing on embayed beaches 1 using a numerical model we show that the surf zone of embayed beaches systematically flushes out more floating material simulated using passive tracers than on open beaches with most exits occurring through the headland rips for obliquely incident waves a headland rip acts as a persistent conduit for transporting floating material out of the surf zone and into the inner shelf region wave angle and embayment size determine which headland rip upwave or downwave flushes out more the surf zone material for narrow embayed beaches passive drifters exit the surf zone through the upwave headland rip for wider embayed beaches the longshore current has enough room to develop and is further deflected against the downwave headland where most drifters exit the surf zone our results indicate that wave exposed rugged coasts strongly enhance exchange of floating matter e g pollutants and nutrients at the ocean continent interface

morphodynamics of structurally controlled headland bay beaches in southeastern brazil a review abstract this paper presents a comprehensive review on the interaction between hydrodynamic processes beach morphology and sedimentology at large scale coastal behaviour along the coastline of santa catarina between laguna and sao francisco island a microtidal east coast swell environment with headland and bay geomorphologies the parabolic bay shape equation has proven to be a convenient and practical tool for studying the stability of the headland bay beaches tombolos and salients in santa catarina the beaches exhibit different patterns of sediment removal as a function of the degree of beach curvature in highly curved beaches there is a well developed shadow zone and a range of morphodynamic conditions from a sheltered low energy beach adjacent to the downdrift headland to a high energy exposed beach on the straight end of the headland bay beach the less curved beaches instead tend to show more uniform behaviour since they are directly exposed to incident waves there is no obvious relationship between average wave height and mean grain size showing the importance of sediment source to characterize the sedimentary distribution patterns in the study area the analysis of beaches showed that beach morphodynamics and sequence profiles for a bay headland coast in a microtidal east coast environment is a function of geological inheritance e g distance between headlands and orientation nearshore and inner shelf morphology coastal plain morphology and sediment source and hydrodynamic factors wave conditions oceanic wave exposure and relative tidal range

dynamic equilibrium planform of embayed beaches part 1 a new model and its verification abstract equilibrium beach formulations are useful tools for diagnosing and managing coastal engineering problems providing solutions for beach erosion problems headland bay beaches hbbs can be used as equilibrium coastal systems for stabilizing coastlines and mitigating erosion problems these embayed beaches may exist in a state of static or dynamic equilibrium throughout the literature several equations can be found for obtaining the static equilibrium planform sep of headland bay beaches hbbs with almost negligible net littoral drift rates however the formulations used to define the dynamic equilibrium planform dep of embayed beaches with specific net sediment transport rates are scarce and based on a limited number of studies this paper proposes a new derived formula for obtaining the planform shape of hbbs in dynamic equilibrium conditions the formula represents a general form of the parabolic bay shape equation pbse with modified coefficients as a function of both the wave obliquity and the net littoral drift rate passing through the bay q the angular difference d between the direction of the mean wave energy flux at the diffraction point of the headland and the beach orientation down coast is also incorporated in the proposed formula the model was verified against natural hbbs in dynamic equilibrium with different net littoral drift rates along the brazilian coast producing good results

glacial conditions in the northern molucca sea region indonesia abstract palynological planktonic foraminiferal and stable isotope data from a sediment core in the northern mollucca sea have been used to evaluate regional glacial climatic and hydrographic conditions the palynological record shows that in glacial time the climate was drier than today indicating a weakened influence of the northwesterly winds at that time the drier climatic conditions at glacial time were associated with a higher lapse rate which together with a lower sea level resulted in a large expansion of the lower montane oak forests on the nearby island of halmahera glacial mollucca sea surface water salinities were probably higher than today while glacial surface water temperatures might have been close to present day values the deep chlorophyll maximum dcm layer in the northern molucca sea at glacial time was more productive and cooler than today probably the result of the inflow of cooler and nutrient enriched subtropical lower water from the pacific the less asymmetrical high latitude ice coverage at glacial time and the particularly strong increase in the pole to equator thermal gradient on the northern hemisphere provides theoretical evidence that the intertropical convergence zone itcz shifted equatorwards and oscillated over a more narrow latitudinal range than today this inferred configuration of the itcz at glacial time however fails to explain the observed increased aridity in the study area at that time we propose therefore that the drier glacial climatic conditions are related to a possible disturbance in the el nino southern oscillation enso system

relocation of earthquakes in the new madrid seismic zone estimation of 1d velocity structure and geometry of a seismogenic fault abstract determination of reliable hypocenters of earthquakes is crucial to earthquake seismology and to evaluate hazards associated with earthquakes there are many associated computer codes for this purpose however most of the location algorithms are designed to determine hypocentral parameters based on previously determined velocity models in contrast we employed a location method that is independent of the initial velocity model using a genetic algorithm ga to determine an optimal 1d velocity model and the locations of earthquakes using this ga we relocated earthquakes that occurred in the new madrid seismic zone nmsz in the central united states between october 1989 and august 1992 the goal of this work was to delineate the possible fault planes by reliable relocation of those earthquakes and to determine a 1d velocity structure for the nmsz a total of 502 earthquakes recorded by 37 portable array for numerical data acquisition panda stations were used in the relocation study in the relocation process the root mean square travel time residuals were reduced by 35 corresponding to an average of 2 3 km deeper in depth 0 7 km shift in latitude and 0 8 km shift in longitude compared with those in the initial catalog locations the hypocenters of the earthquakes can be subdivided into four groups based on their spatial distributions the group that corresponds to the cottonwood grove fault cgf in the southwestern nmsz represents a very steep plane whereas the other three groups fall into reelfoot fault rf we inverted p and s wave travel times from the new hypocentral parameters to determine 1d velocity models the resulting eight layered velocity models consist of a 2 km thick surface layer followed by seven 2 km thick layers with v p ranges from 5 36 to 6 74 km s and v s ranges from 2 83 to 3 90 km s for both cgf and rf regions online material interactive visualizations of hypocentral distributions

the vegetation and climate at the last glaciation on the emerged continental shelf of the south china sea studies on the dispersal mechanism and source areas of pollen from hemipelagic sediments recovered from the continental slopes of the south china sea scs reveal that vegetation existed on the exposed shelves at the last glacial maximum lgm and the latter part of the marine isotope stage 3 at the low sea level stand artemisiadominated grassland covered the northern continental shelf and tropical lowland rainforest and mangroves grew on the southern shelf sunda land consequently the climate in the northern scs must have been much colder and drier during the last glacial period compared to the present sunda land experienced only a marginally lower temperature but was not drier than today the enhanced contrast between the northern and southern parts of the scs in vegetation and climate during the lgm may be ascribed at least partly to the strengthening of winter monsoon during the last glacial period 2000 elsevier science b v all rights reserved

30 000 year vegetation and climate change around the east china sea shelf inferred from a high resolution pollen record ahigh resolutionpollenrecordderivedfromdg9603corerevealsvegetationandclimatechangesontheeast chinaseashelf ecss duringthepast30000years from29 8to26 6calkabp theecsswascoveredbywarm temperate forest steppe and wetland indicating a relatively temperate and moist environment during the period of 26 6e14 8 cal ka bp including the last glacial maximum wetland and temperate forest steppe developedaroundtheecss from14 8to5 3calkabp sea levelcontinuouslyrose andtheecsswasgradually submerged in some exposed areas of the ecss and lower reaches of the yangtze river northern subtropical forest withplantsofquercus evergreen castanopsiselithocarpusandtsuga developedinsteadoftemperate forest steppe and wetland the pollen record shows that the rainfall and temperature increased continually during the period of 14 8e12 8 cal ka bp at the end of this period subtropical forest expanded and even reached the level of holocene optimum period early mid holocene in the younger dryas period 12 8e11 1 cal ka bp a rapid increase in the proportion of arboreal taxa especially quercus deciduous tree and a slight decrease inquercus evergreen tsuga and herbs componentindicatesa mild climatewithhigher precipitation from 11 1 to 5 3 cal ka bp the northern subtropical forest was widely distributed around the ecss region suggesting a relative warm and humid condition in the early holocene the subtropical forest component declined slightly and herbaceous taxa increased reflecting a relatively drier and cooler climate during the period of 9 0e7 0 cal ka bp in the past 5 3 cal ka bp forest vegetation in the lower reaches of the yangtze river was deforested severely possibly caused by human activity

the extreme 2013 2014 winter storms beach recovery along the southwest coast of england abstract sand and gravel beaches naturally act as a coastal buffer absorbing wave energy and dynamically adapting to the seasonal and long term wave climate significant shifts in nearshore morphology can occur during extreme wave events which can have a significant impact on coastal vulnerability during the winter of 2013 14 the atlantic coast of europe received an unprecedented sequence of very energetic wave conditions 8 week mean offshore h s 4 4 m these events caused extensive physical beach and dune erosion and socio economic flooding damage to infrastructure impacts throughout the west coast of europe many monitored sites in the uk and france were in their most eroded state since morphological records began 5 10 years we consider the geomorphological significance of the storm response at 38 natural beaches in the southwest of england ranging from semi sheltered reflective gravel barriers to ultra dissipative exposed sand beaches with dunes the extent and patterns of post storm recovery are examined in detail at three beaches with characteristic storm response behaviours exposed sandy beaches were dominated by cross shore transport processes leading to significant loss of sediment offshore from the intertidal zone 200 m 3 m exposed gravel beaches were dominated by overwash with significant loss landward and semi sheltered sites exposed to more oblique wave forcing were dominated by a rotational response due to alongshore sediment redistribution due to these contrasting responses mechanisms and timescales for beach recovery displayed strong inter site and intra site variations in offshore and rotational cases the recovery processes were multi annual comprising seasonal to decadal signals and were intrinsically linked to the storm response mechanisms while permanent losses occurred when overwash dominated we show that post storm recovery does not necessarily occur during calm periods and that in many cases high energy wave events appear to be essential for recovery of sediment offshore and counter rotation our results highlight the significance of dominant climatic oscillations multi annual storm sequencing storm tracks and resultant variations in wave angle in controlling the impact that extreme wave events have on contrasting sand gravel beaches in exposed sheltered locations