multiple stage deglacial retreat of the southern greenland ice sheet linked with irminger current warm water transport 1 there is limited knowledge pertaining to the history of the greenland ice sheet gis during the last glacial interglacial transition as it retreated from the continental margins to an inland position here we use multiproxy data including ice rafted debris ird planktonic isotopes alkenone temperatures and tephra geochemistry from the northern labrador sea off southwest greenland to investigate the deglacial response of the gis and evaluate its implications for the north atlantic deglacial development the results imply that the southern gis retreated in three successive stages 1 early deglaciation of the east greenland margins by tephra rich ird that embrace heinrich event 1 2 progressive retreat during allerod culminating in major meltwater releases 18o depletion of 1 2 at the allerod younger dryas transition 12 8 13 0 kyr b p and 3 a final stage of glacial recession during the early holocene 9 11 kyr b p rather than indicating local temperatures of ambient surface water the alkenones likely were transported to the core site by the irminger current we attribute the timing of gis retreat to the incursion of warm intermediate waters along the base of grounded glaciers and below floating ice shelves on the continental margin the results lend support to the view that gis meltwater presented a forcing factor for the younger dryas cooling

rapid flooding of the sunda shelf a late glacial sea level record the increase in sea level from the last glacial maximum has been derived from a siliciclastic system on the tectonically stable sunda shelf in southeast asia the time from 21 to 14 thousand calendar years before the present has been poorly covered in other records the record generally confirms sea level reconstructions from coral reefs the rise of sea level during meltwater pulse 1a was as much as 16 meters within 300 years 14 6 to 14 3 thousand years ago

human cultures and environmental changes in the pleistocene holocene transition in the japanese archipelago abstract the accumulated archaeological records have shown that hunter gatherer societies turned from mobile to sedentary ways of life through the transition from the terminal pleistocene to the initial holocene ca 15 8 ka in japanese archipelago this paper discusses the historical processes seen among prehistoric human cultures societies subsistence and environmental changes in this transitional period namely the shift to the jomon culture after the at eruption which is a huge volcanic eruption in southern kyushu in ca 25000 14 c bp population contraction of large mammals as well as a rapid shift to cold dry condition and expansion of coniferous forest pushed hunter gatherers to change their hunting target from large mammals by broad foraging to middle to small mammals in small areas and formed matured regional societies the jomon culture is thought to have stemmed from these societies but is more varied regional and sophisticated than the palaeolithic one resulting from the complex environmental change of the pleistocene holocene transition the emergence of oceanic climate and fine grained ecological settings shaped the unique culture for example the spread of broadleaf forests supplied plentiful nuts and continental shelves formed through coastal transgression furnished ample marine resources because these new ecological settings were formed the jomon population could have become dependent on gathering and fishing and shifted to a sedentary subsistence strategy furthermore increase of precipitation and diverse rainfall patterns encouraged diverse ecological settings leading to the formation of various regional jomon cultures this paper presents such complex trajectories for the jomon culture

searching for eustasy in deglacial sea level histories abstract perturbations to the earth s gravity field and solid surface associated with glacial isostatic adjustment gia cause the total observable sea level change to depart from the eustatic curve which is defined as a spatially uniform height shift of the ocean surface to accommodate any mass gained lost from grounded ice in this study we apply a state of the art model of gia induced sea level change to quantify the magnitude and spatial form of this departure at the global scale for a range of model parameters with an aim to identify regions that are well suited to obtain accurate and precise estimates of eustatic sea level and therefore past grounded ice volume in general our results indicate that eustatic sea level is not a directly measurable quantity and so must be estimated by subtracting a model derived estimate of non eustatic contributions from observations in this regard we use our results to isolate regions where this procedure can be applied with optimal accuracy and precision that is where 1 the gia predictions are relatively insensitive to plausible ranges in input parameters and 2 where the non eustatic contribution is small i e the predicted sea level closely approximates the eustatic value we present maps that can be employed by the field community to identify areas where sea level reconstructions would be well suited to arrive at robust estimates of eustatic sea level note that sea level changes associated with tectonic motion and changes in ocean water temperature salinity which also lead to departures from eustasy are not considered in this analysis

holocene sea level changes in the indo pacific holocene sea level reconstructions exist from many locations in the indo pacific region despite being a large geographical region the nature of holocene sea level change is broadly similar in all locations differences do exist however in the timing and magnitude of the mid holocene high stand mhhs and the nature of late holocene sea level fall across the region when the indo pacific is subdivided into smaller regions these discrepancies do not disappear and in some cases the discrepancies are large within a single coastline it is clear from this analysis that the fundamental criteria to produce accurate local relative sea level curves are hardly ever met there are serious problems associated with the correct interpretation of sea level indicators and their relationship to mean sea level and with the quality of age determinations a consistent methodology throughout the indo pacific for the analysis of sea level data is lacking future sea level analysis from far field locations must involve the application of a consistent methodology in order to allow meaningful comparison between studies this should help to resolve the ongoing debate about the magnitude and timing of the mid holocene high stand and the nature of late holocene sea level fall across the region

clay mineral signature of the nw atlantic boundary undercurrent abstract surface sediments were sampled along 2 transects across the iceland and irminger basins and in the labrador sea clay mineral assemblages deduced from x ray analyses of the carbonate free

origin and consequences of cyclic ice rafting in the northeast atlantic ocean during the past 130 000 years deep sea sediment cores recovered from the northeast atlantic ocean were examined in order to elucidate the influence of the earth s orbital parameters on major ice rafting analyses of coarse grained ice rafted debris and planktonic foraminifers revealed a strong reaction to the precession signal since 130 000 yr b p dropstone layers have been deposited each half period of a precessional cycle 11 000 1000 yr ice rafting occurs during times of winter minimum summer maximum insolation and summer minimum winter maximum insolation in the first case high summer insolation forces meltwater discharge from the ice sheets into the polar seas which subsequently enhances formation of sea ice during the winter in the second case growth of continental ice enhances iceberg production which also leads to a salinity reduction of surface seawater both situations result in a southward penetration of polar water thus the marine record of dropstones documents ice rafting not only during weichselian stades but also during cold events within interstades the regularity of ice rafting yields a useful framework to calibrate and elucidate climatic changes not only in the region of the north atlantic ocean but also in remote areas such as the pacific ocean and the antarctic

numerical modelling of the laurentide ice sheet in the baffin island region the role of a cumberland sound ice stream a numerical model reconstruction was made of the northeastern laurentide ice sheet in the baffin island foxe basin region using geophysical terrestrial and marine geologic evidence for initial

coastal paleo environment and sea level change at macassa bay southern mozambique since c 6600 cal bp changes in holocene coastal paleo environment and sea level variations have been recorded in estuary sediments from macassa bay southern mozambique methods include analysis of fossil diatoms sediment stratigraphy mineral magnetic properties stable carbon and nitrogen isotope composition and carbon and nitrogen content the chronology based on six ams c 14 dates suggests a basal age of the sediment core of c 6600 cal bp calibrated years before present the multi proxy dataset implies two phases when the site was experiencing marine conditions and tentative sea level high stands 1 between c 6600 6300 cal bp which is contemporary with the last phase of the global transgression and the holocene climatic optimum and 2 between c 4700 1000 cal bp a period when sea level curves from the region suggest occasional minor sea level high stands between these phases c 6300 4700 cal bp the environment within the macassa bay estuary was less influenced by marine processes and studied proxies indicate a freshwater phase associated with relatively low sea levels after c 1000 cal bp a terrestrial environment prevailed at the site probably as a result of a combined effect of sea level lowering and high accumulation of organic peat within the estuary c 2011 elsevier ltd and inqua all rights reserved

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

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

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

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

9000 years of sea level change along the southern african coastline abstract beachrocks are good indicators of sea level stillstands on microtidal coastlines and data for this sea level curve is mainly based on dating a series of holocene beachrocks and planation episodes on the southeast african coastline sea level reached its present level along the southern african coastline at ca 6500 bp sea level then rose depositing a series of beachrocks at an elevation of 2 75 m this mid holocene sea level highstand persisted for a period of 2500 years with a 3 5 m stillstand dated at 4480 bp being the highest sea level reached during the holocene in post holocene sea level optimum times a regression occurred lowering sea level to its present level at 3880 bp and down to 2 m at approximately 3000 bp subsequently sea level rose to 1 5 m at 1610 bp and attained its present level at about 900 bp the mid holocene sea level highstand appears to have resulted from a combination of isostatic emergence and the steric expansion of seawater relating to warmer ocean temperatures associated with the holocene hypsithermal event on the eastern agulhas bank

biomarker determination as a provenance tool for detrital carbonate events heinrich events fingerprinting quaternary glacial sources into baffin bay sedimentary deposits associated with heinrich events are anomalously rich in detrital carbonate off hudson strait the dominant carbonate is calcite whereas at distal sites in the north atlantic dolomite is dominant more diagnostic a significant source for dolomite is its outcrop at the northern end of baffin bay where major ice streams from the laurentide innuitian and greenland ice sheets converged the provenance of samples containing detrital carbonate mainly dolomite from a core in baffin bay has been confirmed using organic geochemistry to distinguish between alternative sources based upon the thermal maturity of organic matter in carbonates of the source region the core contained five distinct carbonate units dating between 14 and 51 cal ka bp and indicates significant ice stream instability associated with iceberg calving and significant volumes of meltwater the exact temporal relationship to heinrich events is not yet clear a long mid wisconsin interval 38 to 22 cal ka bp devoid of detrital carbonate suggests a major reduction in ice extent at high northern latitudes the core samples yield thermally sensitive biomarker ratios comparable to those from laurentian carbonates in the canadian arctic islands but unlike those from north greenland identifying the former region as their provenance however a late holocene sample from off newfoundland shows a stronger affinity with greenland 2007 elsevier b v all rights reserved

holocene mangrove dynamics and relative sea level changes along the tanzanian coast east africa abstract there is continued uncertainty regarding the rate timing duration and direction of holocene sea level for the indian ocean and indeed the wider tropical realm we present the first synthesis and a new chronology for holocene relative sea level rsl using a range sediment cores retrieved from mangrove ecosystems in three locations along coastal tanzania this study applies the relationship of ratios between the key mangrove taxa of sonneratia bruguiera ceriops s bc ranging from 0 to 22 9 and sonneratia rhizophora s r ranging from 0 to 2 29 vegetation and altitude to interpret mangrove dynamics and refine the vertical errors associated with relative sea level change the variations in mangrove taxa ratios in the sediment cores obtained from each site shows mangrove development at different periods during the holocene from around 7900 cal yr bp an early to mid holocene rsl rise occurred from 7900 to 4600 cal yr bp that may have reached a higher level than present a lower rsl occurred after 4600 cal yr bp resulting in mangroves retreating seaward at all three study locations before a low magnitude rsl rise occurred between 4400 and 2000 cal yr bp another rsl rise is recorded at 500 cal yr bp before falling to a level lower than present at 100 cal yr bp there is evidence of a recent rsl rise recorded from mangrove ratios during the last century in addition the sedimentation rates among sites are relatively different due to different altitudinal ranges with freshwater input sediment supply and progradation having significantly more effect in the rufiji delta 2 1 10 9 mm cal yr 1 than at the zanzibar sites 0 3 6 6 mm cal yr 1

ice rafted debris associated with binge purge oscillations of the laurentide ice sheet the north atlantic sediment record suggests quasi periodic 7000 to 12 000 year period ice rafted debris ird depositions during at least the last glacial period the cause of these heinrich events as they are commonly known is not fully understood however they may point to surges of the ice stream that drained the hudson bay hudson strait region of the laurentide ice sheet we investigate a simple conceptual model of ice stream instability the binge purge model to suggest ways in which the ice stream could have entrained sufficient debris to account for the estimated mass of ird associated with a typical heinrich ird layer in the north atlantic 1 0 0 3 1015 kg we find that freezing of debris laden ice at the bed of the ice stream during the brief 750 years surge phase of the ice stream s hypothesized binge purge cycle can incorporate up to 5 1 1015 kg this amount is sufficient to meet the constraints of the north atlantic sediment record but by no means verifies the binge purge model as the cause of heinrich events

new constraints on late holocene eustatic sea level changes from mahe seychelles this study provides new estimates of globally integrated ice sheet melt during the late holocene since 4 ka bp from seychelles in the western indian ocean a tectonically stable far field location where the necessary glacial isostatic adjustment gia correction is small and is relatively insensitive to predictions using different earth viscosity profiles we compare sea level data from seychelles to estimates of eustasy from two gia models ice 5g and eust3 which represent end members in the quantity of global melt during the late holocene we use data from a range of coastal environments including fringing reef present day beaches fossil plateau and mangrove deposits on the largest island of the seychelles archipelago mahe to reconstruct relative sea level changes our data suggest that extensive coastal deposits of carbonate rich sands that fringe the west coast formed in the last 2 ka and the horizontal nature of their surface topography suggests rsl stability during this period mangrove sediments preserved behind these deposits and in river mouths date to c 2 ka and indicate that rsl was between 2 m and present during this interval correcting the reconstructed sea level data using a suite of optimal gia models based on the two ice models mentioned above and a large number c 350 of earth viscosity models gives a result that is consistent with the sedimentological constraints when uncertainties in both model results and data are considered it is possible to rule out eustatic sea levels below c 2 m and more than a few decimetres above present during the past two millennia this uncertainty is dominated by error in the reconstructions rather than the model predictions we note however that our estimates of eustasy are more compatible with the eust3 model compared to the ice 5g model during the late holocene 2 1 ka bp our evidence from seychelles shows that the timing of when eustatic sea level first rose close to present is between the predictions of the two end member gia models presented here 4 ka bp for ice 5g and 1 ka bp for eust3 using all lines of evidence currently available from mahe we suggest that the eustatic contribution during the last 2 ka has been less than 2 m this conclusion is drawn from a tectonically stable far field region that is relatively insensitive to earth and ice model uncertainties and implies that global eustasy has been relatively insensitive to climate fluctuations over the pre industrial part of the last 2 ka

mangrove pollen of indonesia and its suitability as a sea level indicator we investigated the mangroves of southeast sulawesi indonesia to assess their potential as proxies for reconstructing sea level during the holocene initial investigations confirmed that the mangrove species demonstrate zonations parallel to the shoreline and are dominated by the family rhizophoraceae with avicennia heritiera and sonneratia also important constituents of the mangroves we investigated the vertical distributions of pollen assemblages at three sites partial cca analysis demonstrated that at all three sites elevation was a significant control on the distribution of pollen assemblages in surface samples we combined the three contemporary transects to develop a regional transfer function to explain the relationship between the surface assemblages and elevations using the maximum likelihood ml method the developed transfer function indicated mangrove pollen can be used as a precise indicator of past sea levels with an error of 0 22 m the transfer function was applied to two fossil cores from the wakatobi marine national park and evaluated using the modern analogue technique both cores showed similar patterns in changes of palaeo mangrove elevation and had modern analogues in the contemporary training set we conclude that mangrove pollen is a suitable proxy for reconstructing sea level in tropical environments

pollen analysis of mangrove sediments as a sea level indicator assessment from tongatapu tonga increasing necessity for precision in holocene sea level records calls for definitive sea level indicators to be assessed these are reviewed by use of examples from the s w pacific and the technique of pollen analysis of mangrove sediments evaluated as a high resolution sea level indicator example is given how a fully calibrated sea level reconstruction can be gained from holocene mangrove peat units from tongatapu tonga by application of features established from a modern analogue of surface samples to interpret fossil pollen patterns

the gisp2 δ18o climate record of the past 16 500 years and the role of the sun ocean and volcanoes measured 18o 16o ratios from the greenland ice sheet project 2 gisp2 ice core extending back to 16 500 cal yr b p provide a continuous record of climate change since the last glaciation high resolution annual 18o 16o results were obtained for most of the current millennium a d 818 1985 and record the medieval warm period the little ice age and a distinct 11 yr 18o 16o cycle volcanic aerosols depress central greenland annual temperature 1 5 c maximally and annual 18o 16o for about 4 yr after each major eruptive event on a bidecadal to millennial time scale the contribution of solar variability to holocene greenlandic temperature change is 0 4 c the role of thermohaline circulation change on climate problematic during the holocene is more distinct for the 16 500 10 000 cal yr b p interval analogous to 14c age calibration terminology we express time in calibrated cal yr b p a d 1950 0 cal yr b p the oldest dryas bolling older dryas allerod younger dryas sequence appears in great detail bidecadal variance in 18o 16o but not necessarily in temperature is enhanced during the last phase of lateglacial time and the younger dryas interval suggesting switches of air mass transport between jet stream branches the branched system is nearly instantaneously replaced at the beginning of the bolling and holocene at 14 670 and 11 650 cal yr b p respectively by an atmospheric circulation system in which 18o 16o and annual accumulation initially track each other closely thermodynamic considerations of the accumulation rate temperature relationship can be used to evaluate the 18 o 16o temperature relationship the gisp2 ice layer count years of major gisp2 climate transitions also support the use of coral 14c ages for age calibration

sea level changes and δ18o record for the past 34 000 yr from mayotte reef indian ocean new sea level and 18o curves for the past 34 000 yr based on uranium thorium chronology are proposed for the southwestern part of the indian ocean the archives include cores drilled from onshore coral reefs and submersed samples from foreslope corals of mayotte in the comoro islands the mayotte sea level curve shows a lowstand of 145 5 m below the present level during the last glacial maximum dated at 18 400 yr this lowstand is supported by the maximum18o enrichment in the coral colonies the residual signal 18o controlled by sea surface temperature changes indicates that surface waters 18 400 yr ago were approximately 5 c cooler than present the deglacial sea level rise is clearly recorded with a mean rate of about 1 7 cm yr 1between 18 400 and 10 000 yr ago the deglaciation phase is characterized by a strong18o depletion marked by two pulses related to meltwater discharges into the north atlantic ocean but also characterized by responses specific to the tropical indian ocean

on the origin of late holocene sea level highstands within equatorial ocean basins abstract late holocene sea level highstands of amplitude 3 m are endemic to equatorial ocean basins these highstands imply an ongoing and moderate sub mm yr sea level fall in the far field of the late pleistocene ice cover that has long been linked to the process of glacial isostatic adjustment gia clark et al 1978 mitrovica and peltier 1991 coined the term equatorial ocean syphoning to describe the gia induced sea level fall and they provided the first physical explanation for the process they argued that water migrated away from far field equatorial ocean basins in order to fill space vacated by collapsing forebulges at the periphery of previously glaciated regions we provide a complete physical explanation for the origin of equatorial ocean syphoning and the associated development of sea level highstands using numerical solutions of the equation that governs meltwater redistribution on spherical viscoelastic earth models in particular we separate the total predicted sea level change into contributions associated with ice and meltwater loading effects and by doing so isolate a second mechanism that contributes significantly to the ocean syphoning process ocean loading at continental margins induces a levering of continents and a subsidence of offshore regions that has also long been recognized within the gia literature walcott 1972 we show that the influx of water into the volume created by this subsidence produces a sea level fall at locations distant from these margins indeed over the major ocean basins that is comparable in amplitude to the syphoning mechanism isolated by mitrovica and peltier 1991

inter tidal fixed indicators of former holocene sea levels in australia a summary of sites and a review of methods and models abstract the reconstruction of mid to late holocene marine environments using the calcareous remains of inter tidal fixed biological indicators as sea level proxies is reviewed useful palaeo environmental information can be obtained from the fossil evidence of successive invasions and disappearances of tropical and temperate species within the sub fossil inter tidal biological sequences examples illustrating spatially synchronous late holocene sea level fluctuations are described from 3000 km of north south coastline along eastern australia the method uses tightly constrained species such as the tubeworm galeolaria caespitosa which allows for the precise measurement of relative sea level fluctuations by using the differential between emerged sub fossil encrustations and current distributions of the same species the error range can be defined according to the extent of preservation of the relic distributions particularly the extent that diagnostic boundaries between species limited to different inter tidal zones have been preserved the rapidity of sea level fluctuations is inferred by the preservation from erosion of emerged shell layers as well as discontinuities in the relic biological sequences and the relative preservation of fragile species this apparent rapidity of sea level fluctuations as well as evidence of near uniform synchronous sea level heights along the north south span of the entire australian coast and equally consistent variations australia wide in spencer gulf and rottnest island raises questions about the predicted poleward decline of sea level curves derived from hydro isostatic rebound modelling

comment on catastrophic ice shelf breakup as the source of heinrich event icebergs by c l hulbe et al hulbe et al 2004 argue that the original binge purge model of their coauthor macayeal 1993a 1993b is not appropriate for heinrich events but that a new ice shelf collapse mechanism may work we believe that thenew collapse mechanism disagrees with important dataand that macayeal s original model remains viable afterappropriate modifications we have enjoyed a fascinatingdiscussion with hulbe et al on this topic which isstimulating our thinking and research and we presentsome of the arguments here for a wider audience

glacial debris flow deposits on the baffin island shelf seismic facies architecture of till tongue like deposits abstract 3 d seismic facies modeling of late foxe wisconsin glacial deposits in the savage basin provides important new data concerning the morphology and origin of acoustically unstratified seismic units on high latitude continental shelves savage basin contains a thick sequence up to 110 m of morainal bank deposits unit ii similar to till tongue root deposits described from the scotian and norwegian shelves in 2 d longitudinal cross section unit ii thins and differentiates northward into two acoustically unstratified wedges or till tongue like deposits units iiaw and iibw which are observed to interbed with stratified glacimarine sediments unit i sediment transport was northeastward away from a late glacial ice margin in outer frobisher bay both unstratified wedges are lobate in plan view with the thickest portion 5 m to 50 m lying along the lobe axis upper surface contours are convex to the north and concentric to the lobate margin southward at the transition to the morainal bank the contours become concave to the north this morphology is consistent with that of lobate debris flow deposits with the concave contours defining a zone of sediment failure the data indicate sediment failure within morainal bank deposits which accumulated near the terminus of a temperate tide water ice sheet truncations of unit i reflectors against the lower surface of the debris flows indicate that the flows were deposited episodically and that they remobilized or eroded some of the unit i sediments this unconformable relationship gives the same stratigraphic sequence that king et al 1991 proposed to explain till tongue formation from subglacial meltout beneath buoyant glacier ice in contact with the seabed coalescing debris flow lobes are observed along the entire distal slope of the morainal bank these give the appearance of a continuous till tongue wedge in seismic cross sections taken parallel and distal to the paleoice margin without 3 d geometry reconstructed at contour intervals 10 m the complex lobate morphology could not be resolved

submarine glacial landforms and rates of ice stream collapse the rate of deglacial ice sheet retreat across polar continental shelves and possible ice stream collapse and sea level rise has been much debated high resolution imagery of seafloor morphology is available for many polar shelves and fjords the rapidity of ice retreat is inferred from diagnostic assemblages of submarine landforms produced at ice stream sedimentary beds these landforms exposed by ice retreat across high latitude shelves demonstrate that deglaciation occurs in three main ways rapidly by flotation and breakup episodically by still stands and or grounding events punctuating rapid retreat or by slower retreat of grounded ice submarine landform assemblages imply through the presence of grounding zone wedges overprinting mega scale glacial lineations on many polar shelves that ice stream retreat is more often episodic than catastrophic these observations provide a robust test of the ability of numerical models to predict the varied response of ice sheet basins to environmental changes

the magnetic signature of rapidly deposited detrital layers from the deep labrador sea relationship to north atlantic heinrich layers rock magnetic parameters from deep labrador sea piston core p 094 are useful for recognizing rapidly deposited detrital layers some of which correlate with north atlantic heinrich layers variations in magnetic properties and lithology distinguish two classes of rapidly deposited detrital layers during the last ice age 1 seven detrital carbonate dc layers have high carbonate content and mean magnetite grain diameters about 4 times greater than the background sediments 2 six low detrital carbonate ldc layers have very similar magnetic properties to dc layers but low carbonate content similar to the background sediments the magnetite associated with dc and ldc layers is well sorted and relatively uniform within and between layers ice rafted detritus ird recognized by increased percentage of the 125 micron grain size fraction and by high magnetic susceptibility is associated with most dc and ldc layers but is not the dominant detrital constituent the correspondence of dc and ldc layers with increased grain size of well sorted magnetite but not with coarse fraction content precludes ice rafting as the primary depositional mechanism dc and ldc layers may have been deposited from suspended sediment derived from turbidite activity in the nearby northwest atlantic mid ocean channel namoc this interpretation is supported by a piston core p 013 from a greenland rise site largely but not completely outside the influence of the namoc the association of dc layers with ird and the apparent age correlation of dc layers to north atlantic heinrich layers suggest that the ice advances which produced the ird in p 094 and in correlative north atlantic heinrich layers also triggered turbiditic flows down the namoc several dc and ldc layers however do not correlate with recognized heinrich layers but appear to be coeval with recently discovered high frequency ird rich layers in the north atlantic

on postglacial geoid subsidence over the equatorial oceans we develop two new spectral formalisms for the gravitationally self consistent solution of the sea level equation which governs the redistribution of glacial meltwater on a visco elastic earth the first is a purely spectral technique based on an extension of theory outlined by dahlen 1976 for determining the equilibrium oceanic tide on an elastic planet using this technique with a feasible spherical harmonic truncation level l 30 we can obtain convergence in the computed sea level variations within the degree range l 10 we also develop a second pseudospectral technique however which permits the construction of gravitationally self consistent solutions to much higher degree and order l 100 the pseudospectral formalism is employed here to develop a comprehensive physical explanation for the global pattern of present day sea level variations due to ongoing glacial isostatic adjustment in particular we focus upon a mechanism which we term equatorial ocean syphoning that acts to draw water toward the oceanic portion of the collapsing peripheral bulge that encircles previously glaciated regions the collapse of the forebulge induces a flow of water which is required to maintain hydrostatic equilibrium the syphoning mechanism dominates the relative sea level rsl variation in oceans in the far field of the ice sheets that is beyond the peripheral bulge during periods such as the interglacial of the past 4000 years during which the volume of the ice sheets has not apparently changed appreciably while at the same time isostatic adjustment persists the rsl change in the near field is in contrast dominated by the local vertical displacement of the solid surface finally comparison of gravitationally self consistent predictions of rsl change in the far field with the observational data at small pacific island sites has provided an upper bound of 1 to 2 m for the eustatic sea level rise produced by any recent last 3000 years melting of the antarctic ice sheet

lithic technological and human behavioral diversity before and during the late glacial a japanese case study abstract drastic climate fluctuations occurred during the late glacial lg around 15 000 11 500 cal bp also in the japanese archipelago although some studies have claimed that regional differences in the characteristics of lithic technology and human behavior became apparent at this period recent studies have revealed that they were already apparent as early as the last glacial maximum lgm hence it is important to discuss whether or not the regionality of the lgm had changed by the lg and to understand the socioecologial processes of the pleistocene holocene transition this paper aims to review lithic technological variation in the japanese archipelago before and during the lg and to investigate behavioral diversity in detail focusing on the kyushu region in southwestern japan as the result of the analysis there are clear differences between northern and southern kyushu in terms of lithic technology and behavioral strategy the differences between the two regions continued from the lgm to lg low lithic tool diversity in the northern kyushu indicates high mobility frequency of humans who carried them in addition a high degree of curated reduction strategy and non local high quality lithic raw material use also implies a high magnitude of mobility curated microblade technology had long helped humans to transport and utilize obsidian lithic resources in a wide foraging territory this supposition would be supported by the scarcity of archaeological feature there as well by contrast plenty of archaeological features including trap pits and pit dwellings in southern kyushu implies as many previous studies claimed slightly early establishment of sedentary life way of human groups who inhabited there high lithic tool diversity in the southern kyushu means low mobility frequency of humans who carried them and moreover the low degree of standardization of flake removal technique low degree of curated reduction strategy and the scarcity of use of exotic lithic raw materials all strongly denote that their mobility magnitude was also considerably low they must have adopted fine grained resource exploitation strategies in small foraging territories it is supposed that above differences of behavioral strategy could be explained as different adaptations to different regional environmental settings future investigation would clarify more detailed regional adaptation strategy than ever

depositional facies of late pleistocene heinrich events in the labrador sea late pleistocene heinrich ice rafting events produced layers rich in ice rafted debris in major parts of the north atlantic north of 40 n a high detrital carbonate content points to the hudson strait outlet of the laurentide ice sheet as a dominant source of the icebergs heinrich events were coupled with short term climate fluctuations during the last and penultimate glaciations and provide evidence for cryosphere hydrosphere atmosphere interaction in pleistocene climate change an unsolved problem with heinrich layers has been their high concentration of fine grained detrital carbonate 80 of the total detrital carbonate which cannot have been delivered by icebergs alone we propose combinations of different processes that deposited four sedimentologically different types of heinrich layers ice rafting alone for the coarser sand to gravel sized fractions and the fine fractions in distal regions type iv heinrich layers whereas nepheloid flows deposited the bulk of the fine sediment in regions proximal to the hudson strait type i heinrich layers on the labrador slope turbidity currents spilling over from canyons were also involved in transporting the fine grained carbonate rich material causing an alternation of mud turbidites and thin laminae of ice rafted debris in type ii heinrich layers on the levees of the northwest atlantic mid ocean channel the thickness relationship is reversed mud turbidites deposited by occasional spillover of currents from the channel are thin and alternate with thicker laminae of ice rafted debris type iii heinrich layers

late quaternary stratigraphy and paleoecology of northwest labrador sea abstract sedimentological study of 20 piston cores from the northwestern labrador sea shows that thin bedded distal turbidites are important constituents of the quaternary strata on the continental slope and rise sedimentation on the outer shelf ca 500 900 m is dominated by ice rafting and hemipelagic deposition detailed study of two outer shelf cores reveals a stratigraphic record extending to oxygen isotopic stage 9 studies of foraminifera and dinoflagellates show that subarctic surface waters penetrated into the northern labrador sea during the early middle glacial stages and pollen data indicate that northward advection of warm air masses occurred at the same time microfossil data indicate that late glacial stages were characterized by year around sea ice cover and arctic surface water and by the dominance of cold dry arctic air masses transitions from glacial to interglacial stages are marked by the presence of low salinity melt water these data support models which postulate that open water in the labrador sea played an important role in supplying moisture to laurentide and greenland ice sheets

detrital carbonate rich sediments northwestern labrador sea implications for ice sheet dynamics and iceberg rafting heinrich events in the north atlantic much of the bed of the central and eastern sectors of the laurentide ice sheet was underlain by paleozoic carbonates we propose that pulses of detrital carbonate rich sediments in two cores from the northwestern labrador sea reflect episodes when an ice stream from the hudson strait extended to the shelf break and delivered sediment onto the slope and deep sea plain atomic mass spectroscopy 14 c dating of planktonic foraminifera in cores hu75 009 iv 55 2 4 km water depth and hu87 033 009 1 4 km water depth and 150 km north northwest indicates that the youngest event occurred between ca 14 and 15 ka and another occurred between 19 and 21 ka the two carbonate intervals in northwestern labrador sea cores are coeval with heinrich events 1 and 2 in the eastern north atlantic lat 45 50 n long 20 w where they are associated with an increase in lithic fragments and a drastic reduction in the numbers of foraminifera these changes have been linked with the massive production of icebergs associated with ice sheet surges our evidence indicates that heinrich events 1 and 2 are associated with the dynamics of the hudson strait ice stream and denote considerable glaciological instability

postglacial flooding history of mayotte lagoon comoro archipelago southwest indian ocean abstract four cores from the fringing reefs and five sediment cores from mayotte lagoon comoro archipelago southwest indian ocean which reached the pleistocene holocene boundary form the database of this study they offer the opportunity to reexamine and complete the postglacial sea level curve especially for the time interval between 11 6 to 8 kyr cal bp between 11 6 kyr cal bp until present the history of sea level rise showed the following steps 1 by about 19 mm yr between 11 6 and 9 6 kyr cal bp 2 by 9 mm yr between 9 6 and 8 kyr cal bp 3 by 3 mm yr between 8 and 7 kyr cal bp and 4 by 0 9 mm yr after 7 kyr cal bp until stabilisation at present level at 2 5 kyr cal bp in addition a decline in the rates of sea level rise or even a stillstand is observed between 13 to 11 6 kyr cal bp the flooding of the lagoon of mayotte was controlled by the depth of the reefal passages which were cut by rivers and or due to erosion during the time of emergence since the last interglacial the differences in the shape of the sea level curve from mayotte compared to those from other sites located far from the former glaciated regions are related to 1 the small size of the island 2 the rapid downward movement of this small volcanic island with the oceanic plate into the mantle due to hydro isostatic compensation after addition of meltwater and 3 the location between large continents

new evidence for episodic post glacial sea level rise central great barrier reef australia abstract we present an extensive database of 364 radiocarbon dates from coastal and marine sediments of the central great barrier reef gbr shelf of which 110 are previously unpublished the elevation data have been reduced to a common datum australian height datum ahd and the various sources of error have been assessed using modern lithological and biological relationships with sea level the elements of the radiocarbon database have been converted into sea level indicators the upper bound of the assembled dataset corresponds to a best estimate sea level curve and the full dataset provides a narrow envelope for sea level rise on the gbr shelf for the last 11 12 kyr not including hydro isostatic crustal flexing the envelope is consistent with episodic rise in post glacial sea levels the rising post glacial sea level probably included stillstands or minor falls at ca 45 m ahd at ca 10 5 kyr b p 5 m 7 8 kyr b p 2 m ca 6 kyr b p and 1 7 m 5 5 kyr b p there is evidence for a significant fall in sea level between stillstands at 11 m 8 5 kyr b p and 17 m 8 2 kyr b p stillstand durations apparently ranged between the vertical spread in the derived sea level data is very wide the use of shell material for dating seems unreliable and prone to large and unpredictable errors data from bulk mangrove muds appear reliable for determination of ancient sea level but may at times result in sea level being placed up to 4 m below the true level in situ biogenic carbonates such as preserved oyster beds and coral micro atolls are the most reliable indicators of sea level position while deposits of mangrove mud give a useful first order approximation of ancient sea levels caution should be used in drawing sea level curves from few data points we conclude that the post 11 12 kyr b p relative rise in sea level was episodic on the central gbr continental margin more data are required to define clearly sea level change up to ca 20 m at 9 kyr b p

holocene sea levels and palaeoenvironments malay thai peninsula southeast asia sedimentological and palynological investigations of great songkhla lakes east coast of the malay thai peninsula southeast asia reveal sedimentary sequences rich in palynomorph assemblages dominated by pollen of mangroves and freshwater swamps compared with other regions in southeast asia the assemblages are of relatively low diversity geochronological data indicate that the great songkhla lakes record one of the earliest mangrove environments in southeast asia 8420 8190 cal yr bp which are subsequently replaced by a freshwater swamp at 7880 7680 cal yr bp owing to the decline of marine influence sea level observations from great songkhla lakes and other areas of the malay thai peninsula reveal an upward trend of holocene relative sea level from a minimum of 22 m at 9700 9250 cal yr bp to a mid holocene high stand of 4850 4450 cal yr bp which equates to a rise of c 5 5 mm yr the sea level fall from the high stand is steady at c 1 1 mm yr geophysical modelling shows that hydroisostasy

post glacial sea level changes around the australian margin a review abstract it has been known since rhodes fairbridge s first attempt to establish a global pattern of holocene sea level change by combining evidence from western australia and from sites in the northern hemisphere that the details of sea level history since the last glacial maximum vary considerably across the globe the australian region is relatively stable tectonically and is situated in the far field of former ice sheets it therefore preserves important records of post glacial sea levels that are less complicated by neotectonics or glacio isostatic adjustments accordingly the relative sea level record of this region is dominantly one of glacio eustatic ice equivalent sea level changes the broader australasian region has provided critical information on the nature of post glacial sea level including the termination of the last glacial maximum when sea level was approximately 125 m lower than present around 21 000 19 000 years bp and insights into meltwater pulse 1a between 14 600 and 14 300 cal yr bp although most parts of the australian continent reveals a high degree of tectonic stability research conducted since the 1970s has shown that the timing and elevation of a holocene highstand varies systematically around its margin this is attributed primarily to variations in the timing of the response of the ocean basins and shallow continental shelves to the increased ocean volumes following ice melt including a process known as ocean siphoning i e glacio hydro isostatic adjustment processes several seminal studies in the early 1980s produced important data sets from the australasian region that have provided a solid foundation for more recent palaeo sea level research this review revisits these key studies emphasising their continuing influence on quaternary research and incorporates relatively recent investigations to interpret the nature of post glacial sea level change around australia these include a synthesis of research from the northern territory queensland new south wales south australia and western australia a focus of these more recent studies has been the re examination of 1 the accuracy and reliability of different proxy sea level indicators 2 the rate and nature of post glacial sea level rise 3 the evidence for timing elevation and duration of mid holocene highstands and 4 the notion of mid to late holocene sea level oscillations and their basis based on this synthesis of previous research it is clear that estimates of past sea surface elevation are a function of eustatic factors as well as morphodynamics of individual sites the wide variety of proxy sea level indicators used their wide geographical range and their indicative meaning some progress has been made in understanding the variability of the accuracy of proxy indicators in relation to their contemporary sea level the inter comparison of the variety of dating techniques used and the nuances of calibration of radiocarbon ages to sidereal years these issues need to be thoroughly understood before proxy sea level indicators can be incorporated into credible reconstructions of relative sea level change at individual locations many of the issues which challenged sea level researchers in the latter part of the twentieth century remain contentious today divergent opinions remain about 1 exactly when sea level attained present levels following the most recent post glacial marine transgression pmt 2 the elevation that sea level reached during the holocene sea level highstand 3 whether sea level fell smoothly from a metre or more above its present level following the pmt 4 whether sea level remained at these highstand levels for a considerable period before falling to its present position or 5 whether it underwent a series of moderate oscillations during the holocene highstand

varying sediment sources hudson strait cumberland sound baffin bay to the nw labrador sea slope between and during heinrich events 0 to 4 core hu97048 007pc was recovered from the continental labrador sea slope at a water depth of 945 m 250 km seaward from the mouth of cumberland sound and 400 km north of hudson strait cumberland sound is a structural trough partly floored by cretaceous mudstones and paleozoic carbonates the record extends from 10 to 58 ka on board logging revealed a complex series of lithofacies including buff colored detrital carbonate rich sediments heinrich h events frequently bracketed by black facies we investigate the provenance of these facies using quantitative x ray diffraction on drill core samples from paleozoic and cretaceous bedrock from the se baffin island shelf and on the 2 mm sediment fraction in a transect of five cores from cumberland sound to the nw labrador sea a sediment unmixing program was used to discriminate between sediment sources which included dolomite rich sediments from baffin bay calcite rich sediments from hudson strait and discrete sources from cumberland sound results indicated that the bulk of the sediment was derived from cumberland sound but baffin bay contributed to sediments coeval with h 0 younger dryas whereas hudson strait was the source during h events 1 4 contributions from the cretaceous outcrops within cumberland sound bracket h events thus both leading and lagging hudson strait sourced h events copyright 2012 john wiley sons ltd

mid wisconsin laurentide ice sheet growth and decay implications for heinrich events 3 and 4 a close look at the sedimentology of heinrich event 4 from the northwest labrador sea indicates that an extended ice margin perhaps greater than before heinrich events 1 or 2 h 1 and h 2 existed in the hudson strait region pre heinrich event 4 h 4 and that on the basis of characteristics of the sediment unit heinrich event 4 was different than heinrich events 1 or 2 i e larger ice sheet collapse longer duration dirtier icebergs other data from across the southern and eastern margin of the laurentide ice sheet as well as greenland and the north atlantic support this interpretation possibly indicating a relative mid wisconsin glacial maximum pre heinrich event 4 many of these data also indicate that heinrich event 4 35 ka resulted in serious climatic and oceanographic reorganizations we suggest that heinrich event 4 gutted the hudson strait leaving it devoid of ice for heinrich event 3 we further hypothesize that heinrich event 3 did not originate from axial ice transport along the hudson strait thus heinrich event 3 may be more analogous to the proposed northward advancing ice from ungava bay during heinrich event 0 than to the more typical down the strait flow during h 1 h 2 and h 4 consequently the climatic and oceanographic impacts resulting from heinrich events are highly susceptible to the type origin and magnitude of ice sheet collapse something which varied per heinrich event during the last glacial period

the central labrador sea facies and dispersal patterns of clastic sediments in a small ocean basin abstract the upper 500 m of the 2 km thick sedimentary section in the central labrador sea consists of upper pliocene pleistocene clastic sediments associated with the globally unique submarine trunk channel of the northwest atlantic mid ocean channel namoc and its system of tributaries turbidity currents in the namoc fractionate their sediment load into fine grained mostly silty clayey spill over sediments on the natural levees and coarse grained channel fill sediments the natural levees of the namoc are composite features containing shallow second order channels tributaries and satellite channels which have their own subdued levees these shallow channels are much less efficient in fractionating the sediment into coarse and fine fractions compared to the namoc the second order levees are sandy based on high resolution seismic profiles and sediment cores eight different facies have been differentiated in the surface sediments of the central labrador basin 1 deep channel fill facies on the namoc floor 2 slide and slump facies on the namoc walls 3 spill over facies on the namoc levees 4 channel fill facies of shallow second order channels 5 sandy spill over facies of shallow second order channels 6 debris flow deposits on the namoc levees 7 pelagic sediments with ice rafted debris and 8 contourites

holocene sea level change on the southwest and south coasts of sri lanka abstract 14 c dates of coral and shell samples from sri lanka produce the following results nineteen samples from emerged coral reef patches on small headlands show two different age groups related to high sea levels 6170 70 5100 70 yr b p and 3210 70 2330 60 yr b p respectively buried coral deposits from the present backmarsh also indicate an age of 6110 80 5560 70 yr b p this substantiates the fact that these corals have thrived in bays or lagoons as a result of the marine transgression in the mid holocene comparing ages and heights of the samples with the mean low water spring level which is the highest level of present living corals it is concluded that the mean sea levels between 6170 70 5100 70 yr b p and 3210 70 2330 60 yr b p were at least 1 0 m higher than the present mean sea level

quantitative mineralogy of the yukon river system changes with reach and season and determining sediment provenance the mineralogy of yukon river basin sediment has been studied by quantitative x ray diffraction bed beach bar and suspended sediments were analyzed using the rockjock computer program the bed sediments were collected from the main stem and from selected tributaries during a single trip down river from whitehorse to the yukon river delta during the summer of 2001 beach and bar sediments were collected from the confluence region of the tanana and yukon rivers during the summer of 2003 suspended sediments were collected at three stations on the yukon river and from a single station on the tanana river at various times during the summers of 2001 through 2003 with the most complete set of samples collected during the summer of 2002 changes in mineralogy of yukon river bed sediments are related to sediment dilution or concentration effects from tributary sediment and to chemical weathering during transport carbonate minerals compose about 2 wt of the bed sediments near whitehorse but increase to 14 wt with the entry of the white river tributary above dawson thereafter the proportion of carbonate minerals decreases downstream to values of about 1 to 7 wt near the mouth of the yukon river quartz and feldspar contents of bed sediments vary greatly with the introduction of pelly river and white river sediments but thereafter either increase irregularly quartz from 20 to about 50 wt or remain relatively constant feldspar at about 35 wt with distance downstream clay mineral content increases irregularly downstream from about 15 to about 30 wt the chief clay mineral is chlorite followed by illite smectite there is little to no kaolinite the total organic carbon content of the bed sediments remains relatively constant with distance for the main stem generally 1 to 2 wt with one exception but fluctuates for the tributaries 1 to 6 wt the mineralogies of the suspended sediments and sediment flow data were used to calculate the amount of mineral dissolution during transport between eagle and pilot station a distance of over 2000 km we estimate that approximately 3 wt of the quartz 15 wt of the feldspar 1 wt of the alkali and 25 wt of the plagioclase and 26 wt of the carbonates 31 wt of the calcite and 15 wt of the dolomite carried by the river dissolve in this reach the mineralogies of the suspended sediments change with the season for example during the summer of 2002 the quartz content varied by 20 wt with a minimum in mid summer the calcite content varied by a similar amount and had a maximum corresponding to the quartz minimum these modes are related to the relative amount of sediment flowing from the white river system which is relatively poor in quartz but rich in carbonate minerals suspended total clay minerals varied by as much as 25 wt with maxima in mid july and suspended feldspar varied up to 10 wt suspended sediment data from the summers of 2001 and 2003 support the 2002 trends a calculation technique was developed to determine the proportion of various sediment sources in a mixed sediment by unmixing its quantitative mineralogy results from this method indicate that at least three sediment sources can be identified quantitatively with good accuracy with this technique sediment mineralogies can be used to calculate the relative flux of sediment from different tributaries thereby identifying sediment provenance

human responses to the younger dryas in japan abstract the effect of the younger dryas cold reversal on the survival of late glacial hunter gatherers in the japanese archipelago is evaluated through a synthetic compilation of 14 c dates obtained from excavated late glacial and initial holocene sites 332 14 c dates from 88 sites the estimated east asian monsoon intensity and vegetation history based on the loess accumulations in varved sediments and pollen records in and around the japanese archipelago suggest an abrupt change to cool and dry climate at the onset of younger dryas coupled with the dansgaard oeschger cycles as recorded in greenland the chronometric placement of sites based on an assessment of 14 c dates show that the site numbers decrease from the bolling allerod to younger dryas and increase from the younger dryas to preboreal however human population dynamics inferred from a site distribution analysis was little changed from the previous bolling allerod and to the following preboreal moreover hunter gatherers consistently employed ceramic pottery technology since its emergence prior to the onset of younger dryas while the quantity of ceramic vessels that were undermined during the younger dryas dramatically increased at the onset of the holocene implying that a substantial change in hunter gatherer socioeconomy occurred after the end of younger dryas

modelling holocene relative sea level observations from the caribbean and south america abstract holocene data from the caribbean and the atlantic coast of south america have been critically assessed and a subset of the best quality data are presented these data cover a large north south geographic extent and display a distinct spatial variation we make the first comparisons of this data set to predictions based on a realistic model of glaciation induced sea level change with the main aims of understanding the cause of the observed spatial trend and estimating a eustatic signal for the holocene the spatial variation is dominated by the influence of the ice and ocean mass redistribution on sea level change with the ice induced effect dominating the observed north south trend a best fitting model is applied to estimate a holocene eustatic signal from the observations we find that the model corrected data are consistent with a relatively rapid rise of 7 8 mm yr in the early holocene with a marked reduction in this rate around 7 cal kyr bp from this time until present the model corrected data suggest that the volume of mass transfer between ice sheets and oceans was no more than 1 m eustatic sea level equivalent

late pleistocene trap pit hunting in the japanese archipelago abstract trap pit hunting has been adopted by modern humans in the japanese archipelago from the initial stage of the upper paleolithic 40 15 ka late mis3 and mis2 to the present trap pit hunting found in the japanese archipelago is dated to 40 000 years ago late pleistocene trap pit hunting was mainly identified in the late early upper paleolithic in southern coastal areas of central honshu and in the terminal upper paleolithic in southern kyushu socio ecological conditions of hunter gatherer societies likely affected their choices of trap pit hunting

refining the eustatic sea level curve since the last glacial maximum using far and intermediate field sites the eustatic component of relative sea level change provides a measure of the amount of ice transferred between the continents and oceans during glacial cycles this has been quantified for the period since the last glacial maximum by correcting observed sea level change for the glacio hydro isostatic contributions using realistic ice distribution and earth models during the last glacial maximum lgm the eustatic sea level was 125 5 m lower than the present day equivalent to a land based ice volume of 4 6 4 9 107 km3 evidence for a non uniform rise in eustatic sea level from the lgm to the end of the deglaciation is examined the initial rate of rise from ca 21 to 17 ka was relatively slow with an average rate of ca 6 m ka 1 followed by an average rate of ca 10 m ka 1 for the next 10 ka significant departures from these average rates may have occurred at the time of the younger dryas and possibly also around 14 ka most of the decay of the large ice sheets was completed by 7 ka but 3 5 m of water has been added to the oceans since that time

holocene mangrove dynamics in makoba bay zanzibar abstract pollen and charcoal analyses on sediment cores retrieved across an altitudinal transect in makoba bay zanzibar tanzania set within a chronology provided by 11 radiocarbon dates are used to reconstruct holocene mangrove ecosystem dynamics using the changing ratio of the key mangrove taxa sonneratia bruguiera ceriops s bc relative changes in past sea level are inferred the interpretation of the pollen record is guided by an initial assessment of modern pollen vegetation and vegetation to environmental relationships mangrove communities in makoba bay are recorded from at least the early holocene in what was a similar environment to the present day mangroves migrated landward probably in relation to a sea level rise until the mid holocene as the seaward and central core locations developed as a lower intertidal mangrove area a phase of lower sea level occurred from the mid holocene to 1450 1550 cal yrs bp characterised by the mangrove communities retreating seaward after 1450 1550 cal yrs bp sea level rose again and greater inundation frequency caused mangroves to shift landward gradually falling until reaching the present sea level the recent decrease of mangrove species rhizophora mucronata may result from increasing anthropogenic influences in the mangrove ecosystems during the last centuries as supported by an increase in charcoal

holocene sea level fluctuation in the southern hemisphere abstract if rising sea levels dominate in the northern hemisphere nh falling or fluctuating sea levels predominate in the southern hemisphere sh endogenic processes tectonics isostasy or geoidal changes could explain local or regional mean sea level msl fluctuations but not an hemispherical one evidence from south america africa antarctica australia and the pacific and indian oceans suggest that the holocene transgression rose above the present msl in higher latitudes before the tropics by plotting latitude against the age of msl arrival at present coasts good correlation is observed oceanic salinity mixing has been already proposed to explain this mid holocene sea level fluctuation climate could be the only factor responsible for this hemisphere wide behavior of msl it has been suggested previously that the climate of the sh precedes that of the nh by 3000 years the climatic optimum or maximum warmth occurred predominantly about 6000 bp in the nh but about 10 9000 bp in the sh short term climatic effects on the sea level monsoons southern oscillation el nino phenomena should have significant occurrences during the past in the windiest oceanic hemisphere this latitudinal trend in former msl should be considered when using shorelines as reference points for measuring vertical crustal movements

holocene palynology and sea level change in two estuaries in southern irian jaya southern new guinea leads the continental australian plate into convergence to form the new guinea highlands extensive inter tidal deltas are typical of much of this low gradient equatorial coastline in two adjacent estuaries in irian jaya west papua this study uses present elevations of mangrove species zones as a finite indicator of holocene sea levels from pollen diagrams of estuarine cores all cores showed mangroves at levels well below the present tidal range with landward species zones being replaced over time by seaward zones results show tectonic subsidence in the recent period with late holocene relative sea level rise of 0 67 mm year 1

heinrich event 0 dc 0 in sediment cores from the northwest labrador sea recording events in cumberland sound layers of ice rafted limestone debris rich sediment were deposited in the northwest labrador sea and the north atlantic during the last glacial period 10 80 ka these sediments were deposited by heinrich events h events which record catastrophic collapses of the laurentide ice sheet in the region of the hudson strait these intervals of detrital carbonate rich sediments are referred to as detrital carbonate layers dc in the northwest labrador sea accelerator mass spectrometry ams 14c dates provide a strong constraint on the timing for these events h 1 dc 1 and h 2 dc 2 dc 0 also known as h 0 correlative to the younger dryas cooling event is not as distinct a sediment unit in the northwest labrador sea as dc 1 and dc 2 an analysis of sediments from two cores hu75009 iv 055 and hu75009 iv 056 off the mouth of the hudson strait in the northwest labrador sea basin sheds new light on the missing dc 0 sediment unit timing for the dc 0 event in cores 055 and 056 is bracketed between 11

margin segmentation of baffin bay davis strait eastern canada based on seismic reflection and potential field data abstract the continental margin of baffin island was interpreted from a compilation of seismic reflection and potential field data based on these data it was divided into volcanic and non volcanic segments in the northernmost area coast parallel grabens and continental basement highs are superseded beneath the slope by irregular basement topography in combination with the velocities from refraction data and the lack of a magnetic slope anomaly we propose a non volcanic margin in the central region the seismic data show a limited region with a seaward dipping reflector sequence that may be intercalated with a sedimentary section both north and south of cape dyer extensive volcanic rocks are interpreted at and below seabed consistent with a volcanic margin in the southern region the depth to basement drops rapidly offshore a thick prograding sedimentary wedge produces a high amplitude long wavelength free air gravity anomaly that was previously confused with the continent ocean boundary although some volcanic rocks are mapped in the region this area is adjacent to the non volcanic labrador sea margin and is interpreted to be of similar structure segmentation of the margin by major faults can explain the abrupt transitions from volcanic to non volcanic margin segments the continent ocean boundary for the region is determined based on the potential field and seismic data along the greenland plate in davis strait the continent ocean boundary coincides with the ungava fault zone the continent ocean boundary is used in conjunction with published poles of rotation to evaluate plate reconstructions at chrons 33n and 27n the earlier reconstruction produces an extensive overlap of boundaries in the north the later reconstruction shows a gap in the southern region thus additional information is required to refine the reconstructions

holocene and late pleistocene relative sea level fluctuations along the east coast of india abstract hermatypic coral colonies and intertidal fossil bearing grainstone packstone and sandstone beds of holocene and of a late pleistocene highstand are exposed above the present high tide level htl at a number of locations along the east coast of india from cape comorin to rameswaram being a passive margin boundary free from indications of late quaternary seismogenic movements this sector provides a benchmark for defining minor relative sea level perturbations during the late pleistocene and holocene highstands along a tropical coast lying between latitudes 5 n and 10 n a series of marine terraces carved on and locally blanketted by late pleistocene biotic and terrigenous accumulations occur at different elevations up to 4 4 m above ltl at manappad point possibly signifying discrete stillstand episodes followed by abrupt intervals of rising falling sea level sea level indicators of the holocene highstand occur in this sector as well as along the fringes of the godavari delta further north the holocene highstand reached nearly 3 m above ltl at 7 3 ka remained stable for approximately 1 7 kyr and was followed by a relative sea level fall between 5 2 and 4 2 ka there was a second pulse of relative sea level rise of a few metres leading to a fresh spurt in coral growth along the northern coast of mandapam and rameswaram this was nearly contemporaneous with fresh melting of ice sheets of antarctica the little ice age lia witnessed a minor 1 m relative sea level fall along this coast resulting in rapid diagenetic hardening and infiltration of goethite into the emerged foreshore sand at karikovil and its neighbourhood this was followed by a rise of the sea level during the last few centuries

evidence for massive discharges of icebergs into the north atlantic ocean during the last glacial period sediments in the north atlantic ocean contain a series of layers that are rich in ice rafted debris and unusually poor in foraminifera1 here we present evidence that the most recent six of these heinrich layers deposited between 14 000 and 70 000 years ago record marked decreases in sea surface temperature and salinity decreases in the flux of planktonic foraminifera to the sediments and short lived massive discharges of icebergs originating in eastern canada the path of the icebergs clearly marked by the presence of ice rafted detrital carbonate can be traced for more than 3 000 km a remarkable distance attesting to extreme cooling of surface waters and enormous amounts of drifting ice the cause of these extreme events is puzzling they may reflect repeated rapid advances of the laurentide ice sheet perhaps associated with reductions in air temperatures yet temperature records from greenland ice cores appear to exhibit only a weak corresponding signal moreover the 5 10 000 yr intervals between the events are inconsistent with milankovitch orbital periodicities raising the question of what the ultimate cause of the postulated cooling may have been

radiocarbon dating of mangrove sediments to constrain holocene relative sea level change on zanzibar in the southwest indian ocean mangrove sedimentary deposits are sensitive to changes in sea level and can be used to reconstruct mid to late holocene sea level fluctuations in intermediate and far field locations distant to t

an inflection in the rate of early mid holocene eustatic sea level rise a new sea level curve from singapore this study presents a sea level curve from 9500 to 6500 cal bp for the farfield location of singapore on the sunda shelf in southeast asia the curve is based on more than 50 radiocarbon dates from elevations of 1 43 m to 15 09 m representing sea level index points in intertidal mangrove and shallow marine sediments deposited by sea level rise accompanying deglaciation the results indicate that mean sea level rose rapidly from around 17 m at 9500 cal bp to around 3 m by 8000 cal bp after this time the data suggest but do not unequivocally prove that the rate of sea rise slowed for a period of 300 500 years centred on 7700 cal bp shortly after the cessation of meltwater input to the oceans from the northern hemisphere renewed sea level rise amounting to 3 5 m began around 7400 cal bp and was complete by 7000 cal bp the existence of an inflection in the rate of sea level rise with a slow down centred on 7700 cal bp is broadly consistent with other available sea level curves over this interval and is supported by evidence of stable shorelines and delta initiation elsewhere at this time as well as evidence of comparatively rapid retreat of the west antarctic ice sheet beginning around 7500 cal bp stepped sea level rise occurring shortly after 7500 cal bp and also earlier during deglaciation may have served to focus significant post glacial episodes of human maritime coastal dispersal into comparatively narrow time intervals

surface sea floor and near surface box cores sediment mineralogy in baffin bay as a key to sediment provenance and ice sheet variations to better understand the glacial history of the ice sheets surrounding baffin bay and to provide information on sediment pathways samples from 82 seafloor grabs and core tops and from seven box cores were subjected to quantitative x ray diffraction weight percent wt analysis of the 2000 m all show an abrupt drop in calcite wt post 5 cal ka bp following a major peak in detrital carbonate mainly dolomite this dolomite rich detrital carbonate dc event in jr175bc06 is possibly coeval with the younger dryas cold event four possible glacial sourced end mem bers were employed in a compositional unmixing algorithm to gain insight into down core changes in sediment provenance at the deep central basin estimates of the rates of sediment accumulation in the central basin are only in the range of 2 to 4 cm cal ka surprisingly low given the glaciated nature of the surrounding land

the earliest pottery of the eastern part of asia similarities and differences there are many reasons why the earliest pottery of east asia is so interesting for researchers one of them is that it is a unique source for reconstruction of cultural diversity within late pleistocene according to russian archaeologists for such reconstruction it is necessary to find out how pots were made clay paste composition way of shaping surface treatment firing and decorating and how pots looked based on this perspective it is possible to divide the earliest ceramic assemblages of east asia into three groups first of them include the incipient jomon ones their differentia is plain without rough surface treatment pottery ornamented by hands pinch nail impression clay application and a comparatively high level of unification second group comprises osipovka assemblages compactly located within the low amur river basin they are quite polymorphous but have common distinctive traits such as grog temper comb design of different pattern and combing surface treatment the third group is the most extended and diverse its key feature is only cord surface treatment in a very special manner of rolling of a cord wrapped stick astoundingly the assemblages with this trait occupy the territory from southernmost china to transbaikalia studenoe 1 ust karenga and middle amur river basin gromatukha so it is possible to say they have inner asia spatial distribution thus we can see three different areas of spatial distribution of earliest ceramic assemblages within the eastern part of asia tracking their holocene fate we can find confirmation of such conclusion and suppose that sakhalin north hokkaido and russia maritime form the forth non ceramic area in late pleistocene

holocene sea level fluctuations inferred from the evolution of depositional environments of the southern langebaan lagoon salt marsh south africa a holocene sea level curve is constructed from the facies distribution and radiocarbon ages of sediment recovered from the distal southern salt marsh of langebaan lagoon on the southwest coast of south africa calibrated radiocarbon analyses of an oyster rich bioclastic gravel indicate that the flandrian transgression flooded the lagoon to 0 3 m above present day levels by 6750 years ago 6 8 ka organic matter and shell material dated in distal lagoonal sediments indicate that sea level returned to present day levels by 4 9 ka and have since remained within 61 m of present day levels bleached shell and a hiatus in sedimentation suggest an approximate 1 m sea level lowstand between 2 5 and 1 8 ka changes in the macrobenthos assemblage since 1 5 ka that include the loss of the oysterostrea atherstonei razor clamsolen capensis brown musselarcuatula capensis and periwinkleoxystele variegata reflect loss of hard substrate decreased tidal flow velocities as reworked sands prograded into the southern la

heinrich events massive late pleistocene detritus layers of the north atlantic and their global climate imprint 1 millennial climate oscillations of the glacial interval are interrupted by extreme events the so called heinrich events of the north atlantic their near global footprint is a testament to coherent interactions among earth s atmosphere oceans and cryosphere on millennial timescales heinrich detritus appears to have been derived from the region around hudson strait it was deposited over approximately 500 250 years several mechanisms have been proposed for the origin of the layers binge purge cycle of the laurentide ice sheet jokulhlaup activity from a hudson bay lake and an ice shelf buildup collapse fed by hudson strait to determine the origin of the heinrich events i recommend 1 further studies of the timing and duration of the events 2 further sedimentology study near the hudson strait and 3 greater spatial and temporal resolution studies of the layers as well as their precursory intervals studies of previous glacial intervals may also provide important constraints

distribution thickness and origin of heinrich layer 3 in the labrador sea abstract the presence of heinrich layer 3 hl 3 in the northwest labrador sea has been debated in the literature calypso giant piston core md99 2233 five new standard piston cores and re interpretation of 34 cores from previous cruises confirm the presence of hl 3 in the labrador sea it is identified by high total carbonate concentration up to 45 an increase in coarse fraction content and lighter 18o values in polar species planktonic foraminifer neogloboquadrina pachyderma left coiling as low as 3 1 the age of hl 3 of 27 ka was bracketed in the various cores by about 50 14c accelerator mass spectrometer dates where it is present in ice proximal regions it consists of nepheloid flow deposits at the base and mud turbidites at the top the thickness of hl 3 varies between 4 8 m proximal to hudson strait and 0 9 m distal decreasing rapidly seaward on the upper continental slope hl 3 was too deeply buried to be sampled elsewhere hl 3 is absent in some cores probably due to slumping or erosion associated with sandy turbidity currents or debris flows