sedimentary facies and holocene depositional processes of laura island majuro atoll article i nfo article history the depositional processesthat formed lauraisland majuroatoll marshall islands were reconstructed basedon a facies analysis of island sediments and spine ratios and radiocarbon ages of foraminifera sedimentary facies were analyzed from trenches and drill cores excavated on the island and its adjacent reef flat depositional ages were obtained using benthic foraminifera calcarina whose spines had not been abraded the facies were classified into two types gravelly and sandy the initial sediments of these sites consisted of gravelly facies in the lower horizon and sandy facies in the upper horizon their ages were approximately 2000 cal bp and coincident with the onset of a 1 1 m decline in regional relative sea level which enabled deposition of the gravelly facies half of the sand fraction of the sediment was composed of larger benthic foraminifera the spine ratioshowedthat theirsupply source on the reef flatwaslocated oceansideof theisland the supplysource appears to have been caused by the relative sea level fall this indicates that the studied island was formed by a relative reduction in wave energy and enhanced foraminiferal supply both of which were triggered by the late holocene relative sea level fall

holocene turn on and evolution of the southern great barrier reef revisiting reef cores from the capricorn bunker group abstract extensive drilling of the great barrier reef gbr in the 70s and 80s illuminated the main factors controlling reef growth during the holocene however questions remain about 1 the precise nature and timing of reef turn on or initiation 2 whether consistent spatio temporal patterns occur in the bio sedimentologic response of the reef to holocene sea level rise then stability and 3 how these factors are expressed in the context of the different evolutionary states juvenile mature senile reefs combining 21 new c 14 ams and 146 existing re calibrated radiocarbon and u th ages we investigated the detailed spatial and temporal variations in sedimentary facies and coralgal assemblages in fifteen cores across four reefs wreck fairfax one tree and fitzroy from the southern gbr our newly defined facies and assemblages record distinct chronostratigraphic patterns in the cores displaying both lateral zonation across the different reefs and shallowing upwards sequences characterised by a transition from deep porites faviids to shallow acropora isopora coral types the revised reef accretion curves show a significant lag period ranging from 0 7 2 ka between flooding of the antecedent pleistocene substrate and holocene reef turn on this lag period and dominance of more environmentally tolerant early colonizers e g domal porites and faviids suggests initial conditions that were unfavourable for coral growth we contend that higher input of fine siliciclastic material from regional terrigenous sources exposure to hydrodynamic forces and colonisation in deeper waters are the main factors influencing initially reduced growth and development all four reefs record a time lag and we argue that the size and shape of the antecedent platform is most important in determining the duration between flooding and recolonisation of the holocene reef finally our study of capricorn bunker group holocene reefs suggests that the size and shape of the antecedent substrate has a greater impact on reef evolution and final evolutionary state mature vs senile than substrate depth alone

post glacial sea level rise from a coral record at huon peninsula papua new guinea dating of coral reef terraces can provide a record of changes in sea level which should be pronounced during the transition between glacial and interglacial periods cores drilled from coral reefs at barbados in the equatorial west atlantic1have revealed the sea level changes that occurred during the younger dry as event at the end of the last glacial maximum 11 000 yr bp it has not been known however whether pacific coral reefs can grow at a rate sufficient to keep up with the rise in sea level during such a transition here we report results obtained from a 52 m drill core from the post glacial reef at huon peninsula papua new guinea spanning the interval from 7 000 to 11 000 14c yr bp which show that coral growth kept pace while the relative sea level rose by 50m although the tectonic environment is very different from that at barbados the two records compare well when corrections are made for local tectonic uplift showing that sea level rise was similar at both locations the rate of rise was greatest between 9 000 and 10 00014c yr bp corresponding to the time of the younger dryas

late quaternary reef growth and sea level in the maldives indian ocean abstract based on rotary drilling and radiometric and u series dating we present the first comprehensive data on holocene reef anatomy and sea level rise as well as nature and age of underlying pleistocene limestone in the maldives holocene reefs in rasdhoo atoll central maldives are composed of four facies including 1 robust branching coral facies 2 coralline algal facies 3 domal coral facies and 4 detrital sand and rubble facies branching coral and coralline algal facies predominate the marginal reefs and domal corals and detrital facies preferentially occur in a lagoon reef in addition microbialite crusts are found in lower core sections of marginal reefs microbialites formed during the early holocene in reef cavities holocene reef thickness ranges from 14 5 m to 22 m reef growth started as early as 8 5 kyr bp marginal reefs accreted in the keep up mode with rates of 15 m kyr rate of sea level rise significantly slowed down from 7 6 kyr bp and subsequently gradually rose with rates

deglacial sea level record from tahiti corals and the timing of global meltwater discharge the timing of the last deglaciation is important to our understanding of the dynamics of large ice sheets1 and their effects on the earth s surface2 3 moreover the disappearance of the glacial ice sheets was responsible for dramatic increases in freshwater fluxes to the oceans which probably disturbed the ocean s thermohaline circulation and hence global climate4 7 sea level increases bear witness to the melting of continental ice sheets but only two such records from barbados8 9 and new guinea10 11 corals have been accurately dated but these corals overlie active subduction zones where tectonic movements are large and often discontinuous especially in new guinea so the apparent sea level records may be contaminated by a complex tectonic component here we date fossil corals from tahiti which is far from plate boundaries and thus is likely to be tectonically relatively stable and remote from the locations of large former ice sheets the resulting record indicates a large sea level jump shortly before 13 800 calendar years bp which corresponds to meltwater pulse 1a in the barbados coral records8 9 the timing of this event is more accurately constrained in the tahiti record revealing that the meltwater pulse coincides with a short and intense climate cooling event12 15 that followed the initiation of the bolling allerod warm period12 16 but preceded the younger dryas cold event by about 1 000 years

holocene coral reef development under windward and leeward locations at ishigaki island ryukyu islands japan abstract coral reef growth is largely controlled by the wave energy associated with ocean swells and local winds this growth has responded to changes in wave conditions that evolved in concert with holocene sea level changes we analyzed holocene facies of the ibaruma and fukido reefs of ishigaki island southern ryukyu islands in the context of temporal and spatial changes in wave conditions by comparing present day coral assemblages and internal fossil reef facies four major coral assemblages that developed under different wave energy conditions were recognized six cores recorded a holocene reef sequence consisting of four sedimentary facies that differed in the relative volumes of four coral taxa acropora digitifera and acropora hyacinthus and lesser amounts of favia stelligera and montastrea curta holocene windward reef growth began at 7820 cal years bp after flooding of the pleistocene reef limestone surface the ensuing reef growth kept up with the rapid sea level rise a vertical growth rate of 7 5 m 1000 years during reef nucleation and early growth stages decreased to 3 5 m 1000 years during the main stage of reef framework development the uppermost part of the windward reef consisted of a very robust framework unlike the open framework of the leeward reef ages indicated that the uppermost leeward reef was ca 3000 years younger than the uppermost windward reef these variations in facies development and timing were caused by differences in local wind driven wave conditions

holocene development of the belize barrier reef previously knowledge of the holocene development of the belize barrier reef bbr the largest reef system in the atlantic ocean was limited to one location carrie bow cay we present new data from 11 rotary drill cores taken at 9 locations and 36 radiometric ages that indicate that the bbr was established from 8 26 to 6 68 ky bp on pleistocene reef limestones presumably deposited during oxygen isotope stage 5 the nonsynchronous start of holocene reef growth was a consequence of variation in elevation of antecedent topography largely controlled by underlying nne trending structures from north to south pleistocene elevation decreases along these structural trends probably reflecting differential subsidence and variations in karst topography reef anatomy is characterized by three facies in order of decreasing abundance these facies are represented by corals mainly acropora palmata and members of the montastraea annularis group by unconsolidated sand and rubble and by well cemented coral grainstones rudstones holocene reef accumulation rates average 3 25 m ky the degree of reef consolidation is negatively correlated with holocene thicknesses indicating that slowly growing reefs are better cemented than fast growing ones we present a holocene sea level curve for belize based on 36 dates from this study and 33 dates from our previous studies in the area

new evidence for drowned shelf edge reefs in the great barrier reef australia we present four new high resolution multibeam bathymetry datasets from the shelf edge of the northern great barrier reef gbr analysis of these data combined with chirp sub bottom profiles and existing submersible observation data provides a fresh insight into the detailed morphology and spatial distribution of submerged reefs and terraces at the shelf edge an extensive and persistent line of drowned shelf edge reefs exist on the gbr margin in about 40 to 70 m they appear as barrier reefs up to 200 m wide and comprising twin parallel ridges of rounded pinnacles subtle yet consistent terrace and step features lie between 78 and 114 m seaward of the shelf edge reefs in the southern study area submersible observations confirm that the drowned reefs now provide a favorable hard substrate for live soft corals and algae they form a consistent and extensive seabed habitat that extends for possibly 900 km along the gbr shelf edge the submerged reef and terraces features may reflect a complex history of growth and erosion during lower sea levels and are now capped by last deglaciation reef material

last deglaciation in the okinawa trough subtropical northwest pacific link to northern hemisphere and tropical climate 1 detailed deglacial and holocene records of planktonic delta o 18 and mg ca based sea surface temperature sst from the okinawa trough suggest that at similar to 18 to 17 thousand years before present kyr b p late spring early summer ssts were approximately 3 degrees c cooler than today while surface waters were up to 1 practical salinity unit saltier these conditions are consistent with a weaker influence of the summer east asian monsoon eam than today the timing of suborbital sst oscillations suggests a close link with abrupt changes in the eam and north atlantic climate a tropical influence however may have resulted in subtle decoupling between the north atlantic and the okinawa trough eam during the deglaciation okinawa trough surface water trends in the holocene are consistent with model simulations of an inland shift of intense eam precipitation during the middle holocene millennial scale alternations between relatively warm salty conditions and relatively cold fresh conditions suggest varying influence of the kuroshio during the holocene

evidence for coral island formation during rising sea level in the central pacific ocean the timing and evolution of jabat island marshall islands was investigated using morphostratigraphic analysis and radiometric dating results show the first evidence of island building in the pacific during latter stages of holocene sea level rise a three phase model of development of jabat is presented initially rapid accumulation of coarse sediments on jabat occurred 4800 4000 years b p across a reef flat higher than present level as sea level continued to rise during the highstand island margins and particularly the western margin accreted vertically to 2 5 3 0 m above contemporary ridge elevations this accumulation phase was dominated by sand size sediments phase three involved deposition of gravel ridges on the northern reef as sea level fell to present position jabat has remained geomorphically stable for the past 2000 years findings suggest reef platforms may accommodate the oldest reef islands in atoll systems which may have profound implications for questions of prehistoric migration through pacific archipelagos

holocene sea level changes and barrier reef formation on an oceanic island palau islands western pacific abstract internal facies and development of an oceanic island s barrier reef were revealed by the stratigraphical study of six drill cores in palau islands western pacific the holocene reef development is primarily constrained at its foundation by the antecedent topography of pleistocene substratum holocene barrier reef is an increment on the pleistocene barrier reef which had been subaerially exposed during glacial stages about 8300 cal year bp calibrated calendar years b p branching acropora facies initially formed a bank on the seaward side of a pleistocene limestone surface with a vertical accumulation rate as high as 30 m ka ka 1000 years after 7200 cal year bp when the sea level rise rate decreased reef crest facies caught up with the sea surface with an accumulation rate of less than 2 2 m ka corals found in the reef crest facies are similar to the present day reef crest corals dominated by acropora digitifera and a humilis after the reef crest was formed bioclastic sand and gravel facies prograded lagoonward of the reef crest and consisted mostly of reef derived materials the construction of patch reefs post dated the barrier reef formation the mature barrier reef provided calm conditions inside the lagoon which then led to the construction of patch reefs and fringing reefs sea level changes deduced from the accumulation curves show rapid rise before 7200 cal year bp followed by a slight rise of 4 m at its maximum this change in sea level rise rate inspired the change in reef facies from branching acropora to reef crest

successive reef depositional events along the marquesas foreslopes french polynesia since 26 ka abstract bathymetric surveys of submarine platforms and terraces of the tropical marquesas archipelago french polynesia coupled with sedimentological and paleoecological analyses and radiometric dating of dredged rocks reveal the occurrence of several distinct intervals of reef deposition during the last deglacial sea level rise i e the last 26 000 yr or 26 ky five facies related to reef shallow water and deeper depositional zones have been identified on the basis of their respective biological assemblages facies 1 2 and 3 consist of in situ scleractinian corals mainly porites associated with thick crusts of coralline algae species hydrolithon onkodes h reinboldii lithophyllum pustulatum group and widespread vermetids and victoriellinid foraminifers these assemblages are typical of high energy shallow water reef settings i e upper forereef reef crest and outer reef flat and inner reef flat respectively facies 4 is characterized by the prevalence of halimeda plates mixed with debris of amphiroa and amphistegina spp these algae generally inhabit the inner parts of the reef flat and backreef zones but also the relatively protected deeper parts of outer reef slopes facies 5 is composed of large broken mollusc shells oysters embedded in fine grained sediments with significant numbers of deep living coralline algae mesophyllum sp and planktonic foraminifers locally mollusc shells are covered with microbialite crusts the replacement of shallower assemblages by deeper ones is interpreted as an upward deepening sequence identification of morphological and biological features combined with coral dating provide evidence of 4 reef generations rg between 26 and 9 ka now ranging from 138 to 58 m in depth 1 rg 0 from 26 to 19 ka in the 125 115 m depth interval 2 rg 1 from 18 to 15 ka between 110 and 95 m 3 rg 2 from 14 to 11 5 ka between 80 and 68 m and 4 rg 3 younger than 11 5 ka at around 55 to 60 m the first three units exhibit clear zonation from upper reef slope to reef flat their development was probably interrupted by abrupt rises in sea level and or drastic climate changes such a scenario is similar to observations reported in barbados and hawai i where rapid rises in sea level interpreted as reflecting major melting events of continental ice caused the drowning of reefs the younger unit refers to coral banks similar to those in modern marquesas environments the replacement of typical coral reefs by coral banks may reflect an increase el nino southern oscillation enso frequency and intensity inimical to reef development in the last 12 ka

influence of wave energy on holocene coral reef development an example from ishigaki island ryukyu islands japan abstract wave energy induced by ocean swell and local winds is an important factor controlling the coral reef development here we compare and contrast facies ages and accretion rates of reefs that developed independently along windward and leeward margins of the same island as both reefs face the open ocean swells provide a background of low to medium energy condition with additional energy along windward margins due to prevailing winds this similarity of the wave energy regimes medium to high energy produced a similar framework facies that was constructed by robust branching acropora however much greater lateral accretion rates were observed in the high energy reef than in the medium energy reef also coral cobble facies were only found in the medium energy reef indicating that the reef framework was more susceptible to storm breakage than that in the high energy reef these differences are attributable to the differing biological and ecological responses of corals to wave energy and water motion

late glacial to post glacial sea levels in the western indian ocean late glacial to post glacial sea level changes provide direct evidence of the progress of melting of large ice sheets during the last deglaciation but although the correlation between ice and ocean volumes is incontrovertible the causal link is commonly obscured local effects including tectonics isostatic and hydroisostatic responses and equatorial ocean syphoning impose additional signals that hide the true picture a detailed regional study of the western indian ocean based on the analysis of drill cores carried out through modern reefs in combination with observations and sampling of reef foreslopes and investigations of outcrops provides a comprehensive data base sites from a range of tectonic settings include the microcontinental margins of madagascar the granitic seychelles and the isolated volcanic islands of reunion mauritius and the comoros in which the effects of subsidence can be shown to be small these cover a range of latitudes and comparisons with adjacent sites on continental margins allow the construction of sea level curves that closely reflect the eustatic response and disengage this from the effects of other mechanisms the mayotte foreslope in the comoro islands provides the first coral reef record of sea level change during the early deglaciation in the indian ocean 110 115 m below present sea level between 18 000 and 17 000 yr bp two distinctive reef terraces at 90 and 60 m water depth are dated at 13 600 yr bp and partly attributed to the younger dryas period 12 700 11 600 cal yr bp reef drowning at around 13 500 yr bp may correspond to meltwater pulse 1a and although there were surges in the rate of sea level rise most notably between 11 950 and 11 350 yr bp there is little evidence to support a well defined meltwater pulse 1b reconstructed holocene sea level curves are in good agreement and reflect a rapid sea level rise of about 6 mm yr 1 between 10 000 and 7500 yr bp followed by a clear inflection around 7500 yr bp when the rate fell to 1 1 mm yr 1 modern reefs started to grow 8000 9000 years ago in the post glacial period the rate of sea level rise was 1 1 5 mm yr 1 before stabilization at its present level 3000 2500 years ago curves for the 10 000 6000 yr 1 bp interval correspond closely with those predicted by theoretical models but lie below these in the subsequent period in particular and with the exception of the margins of the madagascar microcontinent influenced by hydroisostatic processes they do not reflect predicted higher sea level stands during the late holocene

relationship between species diversity and reef growth in the holocene at ishigaki island pacific ocean abstract coral reefs are influenced by global and local factors and living corals are currently faced with a potential loss of species diversity knowledge of the relationship between species diversity and reef growth during the holocene is important in terms of accurately reconstructing natural conditions prior to recent disturbances e g human impact pollution and over harvesting and in predicting future scenarios e g abrupt sea level rise coastal change and economic services this study seeks to characterize the holocene and present day reef at ishigaki island in the ryukyu islands focusing on spatial and temporal variations in the relationship between species diversity and reef growth the analysis is based on a drilling core obtained for the holocene reefs and quantitative species diversity data shannon and weaver s diversity index h obtained for the present day reef h was calculated for four coral communities surveyed at the ibaruma and fukido reefs the holocene sequence was dominated by the corymbose coral community e g acropora digitifera a hyacinthus goniastrea retiformis and platygyra ryukyuensis yielding an h value of 1 6 the encrusting coral community e g echinopora lamellose and pachyseris rugosa showed the highest diversity at the reef h 2 2 however this community was not one of the main reef builders during the holocene the massive coral community e g porites lutea and favites chinensis showed the lowest diversity h 0 6 it also made a minor contribution to reef building this community appeared in a shallow lagoon once sea level had stabilized the arborescent coral community e g a formosa and a nobilis was one of the main reef builders although yielding an h value of much less than 1 0 species diversity is not a prerequisite in terms of holocene reef growth thus a few species e g a digitifera a hyacinthus a formosa a nobilis g retiformis and p ryukyuensis from two main reef building communities are important for reef growth these corals that act as reefs are characterized by high growth rates having an upward reef growth rate of 2 12 m kyr 1 in the indo pacific during the holocene

paleoceanography of the tropical eastern pacific ocean the east pacific barrier epb is the most effective marine barrier to dispersal of tropical shallow water fauna in the world today the fossil record of corals in the eastern pacific suggests this has been true throughout the cenozoic in the cretaceous the epb was apparently less effective in limiting dispersal equatorial circulation in the pacific then appears to have been primarily east to west and the existence of oceanic atolls now drowned guyots in the eastern pacific probably aided dispersal similarly in the middle and early mesozoic and late paleozoic terranes in the central tropical pacific likely served as stepping stones to dispersal of tropical shelf faunas reducing the isolating effect of an otherwise wider pacific ocean panthalassa

event preservation in lagoonal reef systems paleontological data suggest that coral populations in the caribbean were consistently healthy for the past 2 3 k y beginning in the 1980s however disease outbreaks bleaching episodes hurricanes and other perturbations caused catastrophic coral mortality and regional turnover an alternative hypothesis based on historical sources posits that coral populations were already declining more than a century ago these hypotheses can be distinguished only if turnover events are reliably preserved in the holocene record of coral reefs push cores extracted from uncemented lagoonal reefs in belize showed that a direct hit by hurricane iris in 2001 did not disrupt the signature of the recent turnover event which entered the subfossil record essentially intact cores from lagoonal systems in several areas of the caribbean do not support the hypothesis that corals declined before the 1980s

holocene sea level change and hydro isostasy along the west coast of kyushu japan abstract mid to late holocene sea level variations have been obtained at sites along the west coast of kyushu japan sea level observations for this relatively stable area are very important for evaluating the crustal tilting associated with the hydro isostatic adjustment due to the last deglaciation and for examining the cause of underwater jomon sites submerged archeological sites during the jomon period of mid holocene typically observed in this region for these purposes we conducted systematic boring samplings at sites from goto island to tamana along the latitude of about 33 n then we performed diatom assemblage and pyrite sulfur analyses of these sediment samples and 14 c datings for intertidal shells in order to get the sea level variations for these sites observations at tsumizu faced to oomura bay with tidal range of 0 9 m show a sea level high stand of 1 m at about 5500 yr b p years before present followed by smoothly falling to the present level evidences for sea level oscillation of greater than 50 cm have not been found here relative sea levels at about 5000 yr b p are however 2 m at goto island 125 km west of tsumizu and 2 m at tamana 50 km east of tsumizu thus observations at sites along the traverse from goto island to tamana are indicative of crustal tilting of about 3 4 m for the distance of 175 km which seems to be consistent with the prediction caused by the hydro isostatic adjustment

response of reef coral communities to sea level rise a holocene model from mauritius western indian ocean the fringing reef at pointe au sable mauritius indian ocean was used to examine the effects of holocene sea level rise on coral growth this reef is about 1000 m wide and comprises a forereef slope 30 m maximum depth a narrow reef crest and a very shallow backreef 1 5 m maximum depth four major coral communities were recognized which developed within relatively narrow depth ranges a pachyseris oulophyllia community deeper than 20 m an acropora tabulate faviid community 20 6 m a robust branching acropora community less than 6 m and a pavona community less than 10m three high recovery cores show the holocene reef sequence is a maximum of 19 3 m thick and comprises four coral biofacies which are similar to counterparts identified in modern communities robust branching tabular branching robust branching domal and foliaceous coral facies a minimum sea level curve for the past 7500 years was constructed using distribution patterns of coral biofacies and radiocarbon dates from corals reconstruction of reef growth history indicates that both offshore and onshore reef zones were developing coevally aggrading at rates of 4 3 mm year 1 from 6900 years b p the reef caught up with sea level only after sea level stabilized changes in coral community and reef growth rates were driven principally by increasing water agitation due to the decrease in accommodation space based on the composition of the successive coral assemblages the reef appears to have grown through successive equilibrium stages

salinity records for the 1997 98 el nino from western pacific corals 1 seasonal sea surface salinity sss records can be of great value in reconstructing el nino southern oscillation enso variability in the equatorial western and central pacific a region where enso related evaporation and precipitation e p changes are dramatic the 18o values of coral skeleton 18ocoral reflect seawater 18o 18oseawater changes which in tropical oceans are also generally influenced by e p changes therefore 18ocoral is a good indicator of rainfall and enso variability we present biweekly data from palau in the northern part of the western pacific warm pool for the period 1998 2000 which indicate a strong quantitative relationship between 18ocoral sea surface temperature 18oseawater and sss the coral skeletal 18o values documented the sss changes after the 1997 98 el nino therefore 18ocoral can be used to estimate paleosalinity changes however the slope of the 18oseawater sss relationship cannot be assumed to be constant throughout the tropics making site specific calibrations is essential

fringing reef growth and morphology a review abstract fringing reefs are generally not simple veneers of coral growth along tropical shorelines extensive research over the past few decades based on radiocarbon dating of holocene reef deposits has indicated that they can develop in a complex variety of ways even though the surface morphology may appear relatively simple the principal factor that appears to determine the growth and morphology of fringing reefs is the available accommodation space sea level fluctuations are important primarily because the sea surface determines the absolute accommodation space for a given reef this means that a reef established during a period of sea level rise will be able to accrete vertically as space is created above it if however the reef establishes at or grows to the sea surface thereby occupying all the available accommodation space it can no longer accrete vertically and begins to build laterally the morphology and chronostratigraphy of a range of holocene fringing reefs are described on the basis of which six fringing reef growth models are identified in model a the fringing reef is established at depth and primarily accretes vertically towards the sea surface reef growth in model b initiates at sea level and due to the lack of vertical accommodation space grows laterally model c has a similar morphology to model b however the reef progrades over a non reefal sediment wedge episodic lateral and vertical growth occurs in model d with a stepwise progradation of the reef front the remaining models are characterised by seaward reef framework behind which unconsolidated sediments accumulate in model e reef crest growth forms a barrier leading to the development of a backreef lagoon model f has a similar morphology to model e except that the reef crest is formed by hurricane rubble accumulation rather than framework accretion and is periodically reworked

catastrophic impact of typhoon waves on coral communities in the ryukyu islands under global warming 1 typhoon generated storm waves generally cause mechanical damage to coral communities on present day reefs and the magnitude and extent of damage is predicted to increase in the near future as a result of global warming therefore a comprehensive understanding of potential future scenarios of reef ecosystems is of prime interest this study assesses the current status of coral communities on ibaruma reef ryukyu islands on the basis of field observations engineering and fluid dynamic models and calculations of wave motion and predicts the potential effects of a super extreme typhoon incident wave height h 20 m wave period t 20 s on the reef on the present day reef massive corals occur in shallow lagoons and tabular corals occur from the reef crest to the reef slope the observed distribution of corals which is frequently attacked by moderate h 10 m t 10 s and extreme h 10 m t 15 s typhoons is consistent with the predictions of engineering models moreover this study indicates that if a super extreme typhoon attacks the reef in the near future massive corals will survive in the shallow lagoons but tabular corals on the reef crest and reef slope will be severely impacted the findings imply that super extreme typhoons will cause a loss of species diversity as the tabular corals are important reef builders and are critical to the maintenance of reef ecosystems consequently reef restoration is a key approach to maintaining reef ecosystems in the wake of super extreme typhoons

key species of hermatypic coral for reef formation in the northwest pacific during holocene sea level change abstract cores from holocene reefs provided a growth history and species level identification of corals and demonstrated the most important reef builders during the formation stage this knowledge is important to determine a principle for reef formation and to provide preservation plans in the near future a biological and sedimentological study of sediment cores recovered from the palau islands and yoron island northwest pacific revealed four major facies corymbose acropora arborescent acropora massive porites and detritus species level observations show that arborescent acropora a muricata and a intermedia contributed to reef growth under low to moderate energy conditions whereas corymbose and tabular acropora a digitifera a hyacinthus and a robusta a abrotanoides and i palifera were key species for reef formation under high energy conditions during holocene sea level rise and the ensuing period of sea level stability once sea level had stabilized massive porites became restricted to areas subjected to low energy turbid conditions these key species are successful corals because the ecological strategy is rapid growth determinate growth a high degree of colony integration strongly resistant to wave action and rapid local dispersion via fragmentation moreover the western boundary current kuroshio flows along the reefs in the northwest pacific and it is easy for key species to distribute throughout the region during the period of holocene sea level rise and stabilization these features are a principle for reef formation during sea level changes these key species played a significant role in holocene reef formation in the northwest pacific however coral mortality caused by climate change has recently been widely reported moreover the decrease in key species abundance in present day reefs has been more severe than that in any other species these geological findings have important implications regarding the appropriate use of coral transplantation and decisions regarding the optimal location and size of marine protected areas

late holocene sea level change on rota and guam mariana islands and its constraint on geophysical predictions abstract holocene emergent reefs and notches are well distributed on rota and guam relative sea level changes at these islands are reconstructed based on geomorphological observations and borings on present and emergent reefs together with 54 radiocarbon dates sea level rose gradually to a maximum of 1 8 m between 6000 and 4200 yr b p and reached its highest level by 4200 yr b p on both islands after 3200 yr b p abrupt uplift caused emergence of the reef by subtracting the tectonic effect we obtained the sea level change in the marianas sea level reached its present level by 4200 yr b p and has remained almost stable since then reconstructed late holocene sea level change in the mariana islands provides constraints on geophysical models of sea level variations

holocene sea level record from corals reliability of paleodepth indicators at ishigaki island ryukyu islands japan abstract holocene sea level change provides direct evidence of the melting of ice sheets however our understanding of the timing and course of such change is limited by a lack of information regarding environmental condition of corals for example holocene sea level curves are compiled based on water depths estimated from the occurrence of a small number of coral species as species identification is difficult work the error associated with this method of estimating sea level exceeds 2 5 m in addition there generally occurs a difference in the living water depth of corals between high energy reefs and low to moderate energy reefs this difference in living water depth also results in an error in reconstructed sea level curves in the present study we analyzed drill core and recorded the vertical distribution of corals at the high energy ibaruma reef and low to moderate energy fukido reef ishigaki island ryukyu islands japan analyses of corymbose acropora a digitifera massive goniastrea g retiformis massive pocillopora p verrucosa massive platygyra p ryukyuensis and other corals enables the accurate reconstruction of a sea level curve because these species are distributed in a narrow range with a weighted mean m w error of between 0 5 and 2 5 m these observation data from ibaruma and fukido reefs can be used to reconstruct holocene sea level curves based on drill core data from ibaruma reef however the two reefs yield contrasting sea level curves the curve reconstructed based on data from fukido reef is several meters deeper than that reconstructed based on data from ibaruma reef this discrepancy reflects the different energy levels of the two reefs high energy at ibaruma reef and low to moderate energy at fukido reef therefore the accurate reconstruction of a holocene sea level curve requires the identification of species from drill core and observations of the vertical distribution of species at the present day reef at a location close to the drilling site the holocene sea level curve reconstructed based on drill core data from ibaruma reef reveals a rapid sea level rise of approximately 7 5 m kyr 1 between 8000 and 6000 cal years bp the rate of sea level rise decreased from 7 5 to 3 5 m kyr 1 between 6000 and 5000 cal years bp a mid holocene highstand occurred at around 5000 cal years bp at a level of approximately 3 2 5 m above the present mean sea level the increase in ocean volume corresponding to this sea level rise indicates that melting of the antarctic ice sheet continued beyond 6000 cal years bp as most of the northern hemisphere ice sheets had melted by 6000 cal years bp resulting in sea levels similar to those of the present day

variability in suspended sediment concentration over mobile sand beds lateral and longitudinal variability in suspended sediment concentration was investigated over dune and upper regime plane beds under steady uniform flow in a laboratory flume a much greater sampling time was required to reliably predict mean concentration in a dune bed than for an upper regime plane bed laterally separated simultaneous samples over both dune and upper regime plane beds were poorly correlated

holocene reef development where wave energy reduces accommodaton space kailua bay windward oahu hawaii u s a abstract analyses of 32 drill cores obtained from the windward reef of kailua bay oahu hawaii indicate that high wave energy significantly reduced accommodation space for reef development in the holocene and produced variable architecture because of the combined influence of sea level history and wave exposure over a complex antecedent topography a paleostream valley within the late pleistocene insular limestone shelf provided accommodation space for more than 11 m of vertical accretion since sea level flooded the bay 8000 yr bp virtually no net accretion 6 m coral framestone accreted at rates of 2 5 6 0 mm yr in water depths 11 m during the early holocene it abruptly terminated at 4500 yr bp because of wave scour as sea level stabilized more than 4 m of rudstone derived from the upper fore reef accreted at depths of 6 to 13 m below sea level between 4000 and 1500 yr bp coincident with late holocene relative sea level fall variations in the thickness composition and age of these reef facies across spatial scales of 10 1000 m within kailua bay illustrate the importance of antecedent topography and wave related stress in reducing accommodation space for reef development set by sea level although accommodation space of 6 to 17 m has existed through most of the holocene the kailua reef has been unable to catch up to sea level because of persistent high wave stress

deglacial meltwater pulse 1b and younger dryas sea levels revisited with boreholes at tahiti reconstructing sea level changes during the last deglaciation provides a way of understanding the ice dynamics that can perturb large continental ice sheets the resolution of the few sea level records covering the critical time interval between 14 000 and 9 000 calendar years before the present is still insufficient to draw conclusions about sea level changes associated with the younger dryas cold event and the meltwater pulse 1b mwp 1b we used the uranium thorium method to date shallow living corals from three new cores drilled onshore in the tahiti barrier reef no significant discontinuity can be detected in the sea level rise during the mwp 1b period the new tahiti sea level record shows that the sea level rise slowed down during the younger dryas before accelerating again during the holocene

holocene variability of the kuroshio current in the okinawa trough northwestern pacific ocean abstract cores 255 and b 3gc from the southern and northern okinawa trough respectively were studied for determining the variability of the kuroshio current on centennial scales during the holocene based on detailed ams 14 c dates stable isotope and planktonic foraminiferal distribution the main flow of the kuroshio current was inferred to re enter the okinawa trough at 7 3 calendar cal kyr bp leading to abrupt changes in sedimentation rate remarkably increased abundance of the kuroshio current indicator pulleniatina obliquiloculata increased sea surface temperature sst and depth of thermocline dot during 4 6 2 7 cal kyr bp the abundance of p obliquiloculata sharply decreased corresponding to a decreases in sst and dot implying that the influence of the kuroshio current weakened at that time possibly as a result of the intensified winter monsoon significantly the kuroshio current proxies e g the difference in sst between the southern and northern okinawa trough display periodicities of 1500 yr and 700 800 yr ascribed to the second harmonic of the 1500 yr cycle in oceanic thermohaline circulation during the holocene the holocene events at 0 6 1 7 3 3 4 6 5 9 8 1 9 4 cal kyr bp in the okinawa trough appear to be the most recent manifestation of the millennial scale climate cycle recorded in the north atlantic arabian sea marine sediment cores and greenland ice cores suggesting global climatic tele connections

anatomy of a modern coral reef flat a recorder of storms and uplift in the late holocene abstract cores from kabira reef ishigaki island southwest japan reveal the internal structure and temporal changes in sedimentary process of a complete coral reef flat the reef crest caught up with sea level at about 4000 yr bp since then it expanded oceanward and the reef pavement has grown landward the backreef structure is composed of bioclasts derived from the reef framework of all the bioclasts corals and coralline algae are most abundant coral fragments coarser than 3 0 o have dominated the backreef sediments since about 2000 yr bp benthic foraminiferal tests first occurred at about 4000 yr bp and their abundance increased significantly starting around 2000 yr bp shallowing of the reef crest is also indicated by the presence of the shallow water benthic foraminifera baculogypsina sphaerulata tests after 2000 yr bp the date 2000 yr bp is coincident with tectonic uplift at kabira reef kawana 1989 we consider this uplift to have caused a relative sea level fall that aided the deposition of coral fragments transported from the reef pavement by storms the relative sea level fall also caused subaerial exposure of the reef crest during low tides and the transition of reef building organisms from corals to shallow water species of benthic foraminifera resulting in a change noticeable in the constituents of backreef sediments the results of this study suggest that the coral reef flat and especially the backreef can be a faithful recorder of relative sea level changes

paleoenvironmental change in the middle okinawa trough since the last deglaciation evidence from the sedimentation rate and planktonic foraminiferal record well dated high resolution records of planktonic foraminifera and oxygen isotopes from two sediment cores a7 and e017 in the middle okinawa trough reveal strong and rapid millennial scale climate changes since similar to 18 to 17 thousand years before present kyr b p sedimentation rate shows a sudden drop at similar to 11 2 cal kyr b p due to a rapid rise of sea level after the younger dryas yd and consequently submergence of the large continental shelf on the east china sea ecs and the retreat of the estuary providing sediment to the basin during the last deglaciation the relative abundance of warm and cold species of planktonic foraminifera fluctuates strongly consistent with the timing of sea surface temperature sst variations determined from mg ca measurements of planktonic foraminifera from one of the two cores these fluctuations are coeval with climate variation recorded in the greenland ice cores and north atlantic sediments namely heinrich event 1 h1 bolling allerod b a and yd events at about 9 4 kyr b p a sudden change in the relative abundance of shallow to deep planktonic species probably indicates a sudden strengthening of the kuroshio current in the okinawa trough which was synchronous with a rapid sea level rise at 9 5 9 2 kyr b p in the ecs yellow sea ys and south china sea scs the abundance of planktonic foraminiferal species together with mg ca based sst exhibits millennial scale oscillations during the holocene with 7 cold events at about 1 7 2 3 4 6 6 2 7 3 8 2 9 6 10 6 cal kyr bp superimposed on a holocene warming trend this holocene trend together with centennial scale sst variations superimposed on the last deglacial trend suggests that both high and low latitude influences affected the climatology of the okinawa trough c 2006 elsevier b v all rights reserved

holocene reef development along the northeastern st croix shelf buck island u s virgin islands abstract eight cores were recovered from buck island underwater national monument u s virgin islands facies were defined based on recovered coral species fabrics observed in core slabs and thin sections and detailed notes on drilling character thirty six radiometric dates constrained the timing of reef accretion together these data provide a detailed history of reef development under varying regimes of sea level rise and physical oceanography holocene reefs around buck island initiated atop a broad antecedent bench at 13 16 meters below present sea level shelf flooding near buck island occurred as early as 9 500 years ago calbp but preserved reefs lagged by as much as 1 800 years earliest reef development was dominated by branching acropora palmata near the shelf edge and massive corals closer to buck island by 7 200 calbp a palmata apparently declined near the platform margin and was absent until ca 5 200 calbp throughout the study area over time the reefs closer to buck island built upward ca 16 m and seaward ca 50 m as the rate of sea level rise slowed and carbonate production increasingly exceeded the accommodation space that was being created reef topography and zonation became progressively more distinct with a palmata dominating the shallow reef crest branching coral apparently disappeared again between ca 3 030 and 2 005 calbp for reasons that are not clear this and the previous decline of a palmata mimic patterns seen around st croix and throughout the caribbean by 1 000 calbp the reefs close to buck island had largely assumed their present character and continued to track slowly rising sea level until the present around 1 200 calbp vertical accretion along buck island bar apparently ceased paradoxically the surface of this outer reef has historically been dominated by large stands of a palmata since the area was first described but rapid coral growth has not resulted in preservation of this species over the last millennium modern community structure mimics facies patterns seen in cores over the past 7 700 years the southern reef crest appears to have remained slightly shallower than its northern counterpart a condition that persists today observations after hurricane hugo in 1989 suggest that this difference in elevation is related to the piling up of debris on the broader southern reef crest by high waves from storms passing south of st croix also facies along the southern reef are more variable in species composition than their northern counterparts a condition that is exhibited by the modern reef community coral abundance and diversity in the cores total coral 20 30 dominated by a palmata are comparable to the community structure present in the late 1970s bythell et al 1993 hubbard et al 1993 in contrast fossil coral abundance and diversity are consistently higher than what was measured in the 1980s and early 1990s total coral 7 14 a palmata 2 after the onset of white band disease a putative pathogen which has recently decimated branching acroporids throughout the region the dominance of branching a palmata in the cores would seemingly reflect an absence of disease or other factors that would discourage its continued abundance in apparent contrast two lengthy gaps in the a palmata record reflect previous disappearances that roughly correspond to similar lapses elsewhere in the caribbean thus the spatial persistence of a species in the fossil record cannot necessarily be equated with its temporal continuity comparisons between changes in modern reefs on a time scale of decades and their fossil forebears must be made with great care understanding the role of short term changes and how they are reflected in the preserved record is thus critical to relating the late holocene a palmata gaps to the recent decline of the species this has important implications for our understanding of how preserved community structure relates to what actually existed in the past and could limit our ability to use the recent geologic record as a proxy to short term future changes in coral reefs

holocene lagoonal sedimentation at the latitudinal limits of reef growth lord howe island tasman sea abstract the southernmost limit to coral reef growth occurs on lord howe island 33 30 s 159 05 e where a discontinuous fringing reef flanks the western side of the island coring and radiocarbon dating indicate that carbonate sediments were first deposited within the lagoon around 6500 radiocarbon years bp coincident with sea level reaching close to its modern level high energy conditions dominated the reef with robust branching corals dominating the developing reef growth of the reef crest between 6000 and 5000 yr bp is inferred to have caused a reduction in the energy conditions within the lagoon resulting in mud deposition during this period sedimentation occurred at average rates of around 5 mm yr though locally up to 10 mm yr which infilled almost all the available accommodation space in the lagoon by 4000 yr bp most of the lagoon had accreted to a level very close to the modern lagoon floor having accumulated over 11 m of sediment in the northern part of the lagoon and possibly up to 30 m in the south sediments younger than 3000 yr bp form a thin veneer over these older units with the main deposition being confined to embayments the coastal plain and the infilling of blue hole depressions the reef and lagoon fringing lord howe island appear to have developed their present form primarily during a phase of luxuriant growth in the mid holocene

continuous record of reef growth over the past 14 k y on the mid pacific island of tahiti two boreholes were drilled through coralgal sequences in the barrier reef edge of the mid pacific island of tahiti and their bases were radiometrically dated at 10 23 0 05 and 13 77 0 05 ka thousand calendar years the sequences are composed mainly of the reef edge acropora gr danai robusta and hydrolithon onkodes assemblage occasionally replaced by reef slope tabular acropora neogoniolithon or domal porites lithophyllum assemblages the response of reef growth to sea level rise has varied according to the framework type and vertical accretion rates have ranged from 9 3 to 20 6 mm yr 1 from a general trend of long term continuous sea level rise tracked by growth the reef edge coralgal assemblages have experienced two distinct changes controlled by the antecedent paleotopography and internal reef processes during the past 13 8 k y at tahiti there is no evidence of any reef drowning event primarily caused by global glacio eustatic perturbations as has been recorded in the caribbean

holocene sea level change and tectonic uplift deduced from raised reef terraces kikai jima ryukyu islands japan abstract kikai jima kikai island is surrounded by four holocene raised coral reef terraces which are thought to be an offlapping sequence of reef deposits caused by combined effects of seismic uplift and holocene sea level change many studies in this region have investigated holocene sea level changes and reef growth but there are relatively few in which reliable sea level indicators are given we have found that pocillopora verrucosa one of the most abundant coral species on the upper reef slopes of fringing reefs in the ryukyus has its peak abundance at a depth of 1 5 m therefore this species is considered ideal for the analysis of relative sea level change and can be used as a dipstick for the holocene reef deposits in this area based on the distribution of p verrucosa on the four holocene raised terraces we calculate relative paleo mean sea levels to be 10 8 11 1 and 8 5 8 9 m for terrace i 5 0 5 3 m for terrace ii 4 0 4 3 m for terrace iii and 1 9 2 5 m for terrace iv these results combined with hitherto known and newly measured radiometric dates 103 total clearly show that the four terraces formed in response to repeated seismic uplifts at 6 3 4 1 3 1 and 1 4 ka and that sea level was higher than present between 7 0 and 6 3 ka

discovery of a submerged relic reef and shoreline off grand cayman further support for an early holocene jump in sea level abstract drilling close to the base of a submerged sea cliff on the terraced eastern shelf of grand cayman has revealed a relic acropora palmata reef at a depth of 21 m below msl ten cores from its crest are principally composed of cobble sized clasts of a palmata set in a matrix of cemented skeletal grainstone the clasts have a distinctive succession of encrusters that indicate rapid burial a photophilic association of crustose coralline algae foraminifera and vermetid gastropods superimposed by a cryptic association of sclerosponges foraminifera and serpulids in addition to rapid burial u th thermal ionization mass spectrometer tims dating of coral clasts within 1 m of the relic reef surface indicates minor temporal mixing with ages between 8 9 and 8 1 ka such mixing and rapid burial is consistent with a hurricane deposit and is identical to deposits found on the crests of modern reefs in relation to its age the preservation of a 18 5 m intertidal notch cut into the submerged sea cliff on the western shelf of grand cayman implies that the crest of the relic reef has been lowered 1 5 2 m by marine abrasion bioerosion at a rate of 0 25 mm yr 1 reconstructing this eroded section using average holocene accretion rates indicates that the reef likely ceased accreting at 7 6 ka at a depth of 19 m comparing these data with other relic reefs in the caribbean indicates that the relic reef on grand cayman died within 160 years of relic reefs on barbados st croix st thomas and north florida this narrow interval of reef demise also coincides with the time when modern reefs were establishing themselves some 4 9 m higher upslope a fact that can only be resolved by invoking a rapid 6 m jump in sea level 7 5 ka ago such a jump would also account for two unexplained events around this time the restricted interval of global delta initiation and the catastrophic flooding of the glacially lowered black sea

reef coralgal assemblages as recorders of paleobathymetry and sea level changes in the indo pacific province the coralgal framework within the outer reef margin of many indo pacific reefs exhibits three main shallow water communities the environmental significance of which can be inferred by comparison with their modern counterparts a community dominated by tabular acropora gr hyacinthus cytherea with branching pocillopora damicornis p eydouxi montipora digitata occasional domal faviids and mm thick crusts of the coralline algae lithophyllum and mesophyllum mainly typical of the 6 15 m paleodepth range a community including robust branching acropora gr danai robusta a humilis a digitifera and subordinate favia stelligera echinopora gemmacea associated to vermetid gastropods and thick coralline crusts of hydrolithon cf onkodes and neogoniolithon cf fosliei flourishing in depths less than 6 m in medium to high water energy settings a community composed of domal porites cf lutea and p cf lobata with occasional acropora gr danai robusta and cm thick crusts of coralline algae in sheltered habitats in depths less than 10 m these biological assemblages allow us to determine relationships between reef growth and paleobathymetry and consequently to reconstruct regional relative sea level curves high water energy reefal assemblages provide stronger evidence for reconstructing sea level curves than low energy buildups because they have generally been controlled by a keep up growth mode subsiding reef sites seem to be more reliable indicators of sea level variations because they usually present expanded reef sequences

holocene key coral species in the northwest pacific indicators of reef formation and reef ecosystem responses to global climate change and anthropogenic stresses in the near future abstract the geological record of key coral species that contribute to reef formation and maintenance of reef ecosystems is important for understanding the ecosystem response to global scale climate change and anthropogenic stresses in the near future future responses can be predicted from accumulated data on holocene reef species identified in drillcore and from data on raised reef terraces the present study analyzes a dataset based on 27 drillcores raised reef terraces and 134 radiocarbon and u th ages from reefs of the northwest pacific with the aim of examining the role of key coral species in reef growth and maintenance for reef ecosystem during holocene sea level change the results indicate a latitudinal change in key coral species arborescent acropora acropora intermedia and acropora muricata was the dominant reef builder at reef crests in the tropics whereas porites porites australiensis porites lutea and porites lobata was the dominant contributor to reef growth in the subtropics between 10 000 and 7000 cal years bp when the rate of sea level rise was 10 m ka acropora digitifera acropora hyacinthus acropora robusta a abrotanoides isopora palifera favia stelligera and goniastrea retiformis from the corymbose and tabular acropora facies were the main key coral species at reef crests between 7000 and 5000 cal years bp when the rate of sea level rise was 5 m ka and during the following period of stable sea level massive porites p australiensis p lutea and p lobata contributed to reef growth in shallow lagoons during the period of stable sea level key coral species from the corymbose and tabular acropora facies have the potential to build reefs and maintain ecosystems in the near future under a global sea level rise of 2 6 m ka as do key coral species from the arborescent acropora facies and massive porites facies which show vigorous growth and are tolerant to relatively deep water low energy environments however these species are likely to experience severe mortality in upcoming decades due to natural and anthropogenic stresses consequently this damage will lead to a collapse in reef formation and the maintenance of reef ecosystems in the near future this study emphasizes the need for research into the conservation of key coral species

postglacial reef development in the south west pacific case studies from new caledonia and vanuatu abstract analysis of reef development in the south west pacific provides valuable information on climatic variations and environmental changes during the past 20 ka here i compare fringing reef development from two sites in different geotectonic settings in new caledonia located on a stable passive margin a lag in reef development is observed and postglacial reefs initiated late between 7 2 and 4 ka in vanuatu located in an uplifting island arc reef development was continuous from 24 to 6 ka and there was no lag with the reef initiating as soon as substrate was available the initiation lag in new caledonia can be attributed to a lack of suitable substrate or to unfavorable oceanographic conditions such as cold sea surface temperature sst which did not allow reef initiation in vanuatu although sst during much of the postglacial sea level rise was probably cooler than present the reef was still able to develop as soon as the substrate was flooded

post glacial evolution of the indo pacific warm pool and el nino southern oscillation recent research has revealed new insights into the temperature size and variability of the indo pacific warm pool ipwp and the nature of the el nino southern oscillation enso since the last glacial maximum lgm sea surface temperature sst reconstructions from foraminiferal mg ca alkenone and revised coral sr ca palaeothermometry agree that ssts in the ipwp during the lgm were similar to 3degreesc cooler than at present in the central portion of the ipwf the rapid post glacial rise in sst led the deglaciation by similar to 3000 years to produce near modern ssts by the early holocene in contrast further west and north post glacial shifts in ssts in the south china and sulu seas are synchronous with abrupt climate changes in the north atlantic new evidence for the nature of the little ice age in the tropics has been obtained from a 420 year record of coral sr ca and 6180 from the great barrier reef australia this indicates that ssts and salinity were higher in the 18th century than in the 20th century the results suggest that the tropical pacific played a role as a source region of water vapour during the global expansion of little ice age glaciers the onset of modern enso periodicities is identified by palaeo enso records throughout the tropical pacific region similar to 5000 years ago with an abrupt increase in enso magnitude similar to 3000 years ago individual enso events recorded by corals reveal that the precipitation response to el nino temperature anomalies was subdued in the mid holocene the apparent non linear onset of enso in the late holocene appears to reflect abruptly enhanced interaction between the southern oscillation and the pacific intertropical convergence zone comparisons of precipitation variability recorded by great barrier reef corals with enso indices for the last 350 years confirms that non stationarity of enso teleconnections is a natural characteristic of modern climate c 2003 elsevier ltd and inqua all rights reserved

continuous reef growth during the last 23 cal kyr bp in a tectonically active zone vanuatu southwest pacific abstract at urelapa island vanuatu sea level rise and a tectonic uplift of 3 mm yr 1 have controlled water depth and the colonization and reef development on a substrate from 23 until 6 cal kyr bp analysis of coralgal assemblages offers insights on the mode of reef growth and on water depth over the reef for the studied period those assemblages precisely dated by the 230 th 234 u method give valuable information on the rate and timing of sea level rise since the last glacial maximum the urelapa reef sequences are characterized by upwards replacement of reef frameworks which indicates changes in wave energy through time the sudden acceleration of sea level rise associated with meltwater pulse 1b at around 11 3 cal kyr bp is marked by a change in reef growth strategy from a keep up mode to a catch up mode we examine the delay in timing of the occurrence of suitable substrates the role of paleoceanographic factors and the influence of possible jumps in sea level

a griggs deformation apparatus set up at lille the classical solid medium apparatus griggs apparatus is generally viewed as a machine of poor accuracy with a large amount of uncertainty however a new generation of equipment with new assemblies and experimental procedures has greatly enhanced the capability of the apparatus experiments performed on the apparatus set up in our laboratory on t oriented yule marble samples show that the yield strength of material can be measured with reasonable precision within 10 mpa and a yield strength as low as 50 mpa can be detected the apparatus is particularly adapted to work on small specimens e g single crystals a few millimetres in size