optically stimulated luminescence age controls on late pleistocene and holocene coastal lithosomes north carolina usa luminescence ages from a variety of coastal features on the north carolina coastal plain provide age control for shoreline formation and relative sea level position during the late pleistocene a series of paleoshoreline ridges dating to marine isotope stage mis 5a and mis 3 have been defined the kitty hawk beach ridges on the modern outer banks yield ages of 3 to 2 ka oxygen isotope data are used to place these deposits in the context of global climate and sea level change the occurrence of mis 5a and mis 3 shorelines suggests that glacio isostatic adjustment gia of the study area is large ca 22 to 26 m as suggested and modeled by other workers and or mis 3 sea level was briefly higher than suggested by some coral reef studies correcting the shoreline elevations for gia brings their elevation in line with other sea level indicators the age of the kitty hawk beach ridges places the holocene shoreline well west of its present location at ca 3 to 2 ka the age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast usa suggesting some regionally contemporaneous forcing mechanism

an improved estimate of lithospheric thickness based on a reinterpretation of tilt data from pleistocene lake algonquin a reinterpretation of relative uplift data associated with the deformed strandline of pleistocene lake algonquin is presented the new analysis is based on a dynamic model that allows for the finite rate of retreat of the laurentide ice sheet and the viscous relaxation of the earth s mantle attention is also paid to the effects of the shape of the load profile on the interpretation in the context of this model the thickness of the lithosphere is constrained to be not more than 85 km this value is based on the assumption of a model ice sheet with a parabolic cross section if the load has a sharper edge a thickness of 110 km is consistent with the data these revised values slightly exceed walcott s original estimate they are on the other hand distinctly lower than the value of 200 km which has recently been inferred by peltier for the thickness of the north american lithosphere the relations between the different estimates are briefly discussed it is suggested that a reconciliation of the estima

environmental significance of bedrock jointing in southern ontario canada the bedrock surface of many glaciated areas is obscured by thick drift deposits in southern ontario canada the buried bedrock surface is dissected by channels infilled with glacial deposits as much as 150 m thick that are part of a wider mid continent preglacial fluvial system that predates formation of the modern great lake basins the infills of bedrock channels form major groundwater aquifers influence regional groundwater flows and contaminant migration to lake ontario and may localize the release of thermogenic methane and radon within heavily urbanized surface environments a quantitative comparison of the regional pattern of bedrock joints and the orientation pattern of buried bedrock channels and modern river valleys shows that all these orientation patterns are virtually coincident buried bedrock channels in south central ontario are not part of a simple antecedent drainage system but were likely predesigned by bedrock joint patterns that have subsequently been propagated upward into overlying pleistocene sediments joints in sediments are of considerable environmental significance for example subsurface contaminant and gas migration in fine grained clayey sediments and of many origins stress release desiccation etc but are widely assumed to be a predominantly surface related phenomena the existence of deeper joints has been noted by some authors but their origin is obscure data presented herein from south central ontario confirm that in addition to surface related joints a second population of bedrock related joints reflecting the upward propagation of bedrock fractures is present in pleistocene sediments of south central ontario

investigating the effects of micro texture and geo mechanical properties on the abrasiveness of volcanic rocks abstract the abrasiveness of rocks is a fundamental rock property that affects sawing and cutting performance wear of tunnel boring machine tbm heads the cerchar abrasiveness index cai test is a commonly used procedure to define rock abrasivity this paper investigates the relationship between quantitative mineralogical and petrographic data and cai values for some selected volcanic rocks in addition the research examines the relationship between physical e g effective porosity and p wave velocities and mechanical e g uniaxial compressive strength ucs brazilian tensile strength bts young s modulus e properties including brittleness values and cai values quantitative mineralogical and petrographic analyses reveal the variations in micro textural properties as defined by different groundmass phenocryst ratios analyses also suggest that the dimensions of opaque minerals and plagioclase feldspar apparently have individual effects on cai values additionally the combined effects of grain size and primary types of constituent minerals have a significant on cai values additionally results of physical and mechanical tests indicate that as p wave velocities increase cai values increase the increasing values of ucs bts and e cause cai values to increase significantly however only one of three brittleness values was found to have a considerable relationship with cai values this research demonstrates the importance of evaluating the micro textural variations and the combined effects of micro texture physical properties and mechanical properties on the cai values of volcanic rocks

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

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

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

early middle holocene relative sea level oscillation events recorded in a submerged speleothem from the yucatan peninsula mexico geomorphological and biological archives of relative sea level change in the western north atlantic caribbean region following the last glacial maximum have traditionally supported the hypothesis o

the paradox of the global standard late ordovician early silurian sea level curve evidence from conodont community analysis from both canadian arctic and appalachian margins abstract relative sea level fluctuations in the late ordovician early silurian were largely driven by gondwana deglaciation three possible short lived ice readvances and the closure of the iapetus ocean this study establishes and compares sea level events on the canadian arctic and appalachian margins of laurentia based on the pattern of conodont communities and demonstrates that sea level events were not synchronous on the two margins conodont data were compared for a the arctic margin from the cape phillips formation richmondian upper ordovician through lower sheinwoodian lower silurian cornwallis island canadian arctic islands and b the appalachian margin from the upper ellis bay becscie merrimack gun river jupiter and chicotte formations richmondian upper ordovician rhuddanian aeronian and most of telychian lower silurian anticosti island quebec the pattern of late ordovician early silurian conodont communities is established based on three cluster analyses on conodonts from cornwallis island 4967 specimens representing 54 species from 77 samples cape phillips formation and anticosti island 1980 specimens representing 21 species from 25 samples upper ellis bay formation 24 839 specimens representing 42 species from 123 samples becscie merrimack gun river jupiter and chicotte formations overall the sea level curves inferred from the distribution of the conodont communities from cornwallis and anticosti exhibit gradual and rapid oscillating patterns respectively specifically during the time interval of the latest ordovician and the early silurian rhuddanian the sea level behaved differently in these two regions 1 during the latest ordovician conodont community changes show the different patterns in the two regions which reflects a transgression on cornwallis but a regression on anticosti 2 during the earliest rhuddanian similar conodont communities arose in both regions but they indicate a regression on cornwallis and a transgression on anticosti 3 in the early rhuddanian these communities were replaced by a deeper water community on cornwallis and a shallower water community on anticosti which suggest a transgression on cornwallis and a regression on anticosti 4 a highstand drove out almost all conodonts from anticosti by the end of rhuddanian which is not seen on cornwallis 5 a deep water conodont community remained almost unchanged on cornwallis from the late rhuddanian to the early aeronian whereas a shallow water conodont community returned to anticosti in the early aeronian however the sea level dropped on both cornwallis and anticosti during the late telychian and the sea level curves show a similar pattern the difference in the sea level pattern during the late richmondian rhuddanian and aeronian on both the northern and southern margins of laurentia reflected by conodont communities is supported by the studies on quaternary glaciation deglaciation events where the melting of an ice sheet was accompanied by sea level change but with variable regional isostatic effects that do not generate a uniform global eustatic signal

constraints on the greenland ice sheet since the last glacial maximum from sea level observations and glacial rebound models abstract geomorphological descriptions of changes in the extent of the greenland ice sheet gis have been combined with glacial isostatic adjustment models to reproduce the sea level history of greenland since the last glacial maximum lgm the contribution to past sea level change around greenland due to ice load changes outside of that region has been considerable 10 s of meters while still contributing a rise of several mm yr 1 today the isostatic contribution to relative sea level around greenland from changes in the gis is found by iteratively perturbing preliminary ice models with different lgm extents and deglaciation starting times the resulting first order model that provides the best agreement between observed and predicted sea level contributes 3 1 and 1 9 m water equivalent of additional ice relative to present day ice volumes at the lgm and younger dryas respectively the gis in most areas does not appear to have extended far onto the continental shelf the exceptions being southern most southwest greenland and northern east greenland as well as at the coalescence of the northwest greenland and innuitian ice sheets changes in ice thickness since the lgm were 500 m along the present day outer coast and 1500 m along some parts of the present day ice margin the observed mid to late holocene fall in sea level to below the present day level and the subsequent transgression seen in some areas implies that the gis retreated behind the present day margin by distances of the order of 40 km before readvancing

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

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

sea level history of the gulf of mexico since the last glacial maximum with implications for the melting history of the laurentide ice sheet abstract sea level records from the gulf of mexico at the last glacial maximum 20 ka are up to 35 m higher than time equivalent sea level records from equatorial regions the most popular hypothesis for explaining this disparity has been uplift due to the forebulge created by loading from mississippi river sediments using over 50 new radiocarbon dates as well as existing published data obtained from shallow marine deposits within the northern gulf of mexico and numerical models simulating the impact of loading due to the mississippi fan and glacio hydro isostasy we test several possible explanations for this sea level disparity we find that neither a large radiocarbon reservoir sedimentary loading due to the mississippi fan nor large scale regional uplift can explain this disparity we do find that with an appropriate model for the laurentide ice sheet the observations from the gulf of mexico can be explained by the process of glacio hydro isostasy our analysis suggests that in order to explain this disparity one must consider a laurentide ice sheet reconstruction with less ice from 15 ka to its disappearance 6 ka and more ice from the last glacial maximum to 15 ka than some earlier models have suggested this supports a laurentide contribution to meltwater pulse 1 a which could not have come entirely from its southern sector

coral reef response to quaternary sea level and environmental changes state of the science there is considerable uncertainty about future sea level projections due to the current poor understanding of the vulnerability and sensitivity of ice sheets to global warming fossil coral reefs represent a unique archive of sea level and associated environmental changes that extend far beyond instrumental records here recent advances in this field are summarized focusing on periods of earth history typified by rapid sea level rise and short term climate excursions sea level and reef response records from the last deglaciation and periods characterized by higher sea level stands and short term and low magnitude sea level oscillations such as the mid to late holocene and the last interglacial are synthesised special emphasis is given to understanding how coral reefs have responded to these changes in terms of reef development architecture and composition finally seven major challenges and future research directions are identified

high resolution windows into early holocene climate srca coral records from the huon peninsula high precision measurements of srca ratios are reported for porites corals from the uplifted holocene coral terraces at huon peninsula papua new guinea the early holocene porites have u th mass spectrometric ages of 8920 60 yr and 7370 50 yr and 234u t values of 145 2 similar to modern seawater the srca coral records provide 5 6 year high resolution near weekly time windows into early holocene sea surface temperatures seasonal temperature fluctuations are generally in the range of 1 c with occasional excursions of 2 c which may indicate the more frequent recurrence of very strong enso el nino southern oscillation events mean annual srca temperatures of 24 2 1 1 c and 22 9 0 8 c have been obtained which are 2 3 c cooler than that exhibited by a modern porites these results indicate that during the early holocene the equatorial western pacific ocean was at least several degrees cooler than present day temperatures this is consistent with late glacial coral records from the caribbean that indicate lower 6 c sea surface temperatures for the equatorial oceans the huon peninsula corals also indicate that ssts were several degrees cooler than those in the caribbean during the early holocene thus although the northern hemisphere summer radiation maximum occurred at 10 ka there appears to have been a significant lag in the response of the equatorial western pacific ocean to this warming cooler early holocene sea surface temperatures in the western pacific may have been due to changing patterns of ocean atmosphere circulation resulting from the exposure of large areas of continental shelf in the southeast asia region a consequence of lower glacial sea levels it is likely that ocean temperatures in the huon peninsula were influenced by the opening at 7 ka of the torres strait that now separates new guinea from the australian mainland

sea level and shoreline reconstructions for the red sea isostatic and tectonic considerations and implications for hominin migration out of africa the history of sea level within the red sea basin impinges on several areas of research for archaeology and prehistory past sea levels of the southern sector define possible pathways of human dispersal out of africa for tectonics the interglacial sea levels provide estimates of rates for vertical tectonics for global sea level studies the red sea sediments contain a significant record of changing water chemistry with implications on the mass exchange between oceans and ice sheets during glacial cycles and because of its geometry and location the red sea provides a test laboratory for models of glacio hydro isostasy the red sea margins contain incomplete records of sea level for the late holocene for the last glacial maximum for the last interglacial and for earlier interglacials these are usually interpreted in terms of tectonics and ocean volume changes but it is shown here that the glacio hydro isostatic process is an additional important component with characteristic spatial variability through an iterative analysis of the holocene and interglacial evidence a separation of the tectonic isostatic and eustatic contributions is possible and we present a predictive model for palaeo shorelines and water depths for a time interval encompassing the period proposed for migrations of modern humans out of africa principal conclusions include the following i late holocene sea level signals evolve along the length of the red sea with characteristic mid holocene highstands not developing in the central part ii last interglacial sea level signals are also location dependent and in the absence of tectonics are not predicted to occur more than 1 2 m above present sea level iii for both periods red sea levels at expected far field elevations are not necessarily indicative of tectonic stability and the evidence points to a long wavelength tectonic uplift component along both the african and arabian northern and central sides of the red sea iv the observational evidence is consistent with tectonic and isostatic processes both operating over the past 300 000 years without requiring changes in the time averaged over a few thousand years tectonic rates v recent bathymetric data for the bab al mandab region have been compiled to confirm the location and depth of the sill controlling flow in and out of the red sea throughout the last 400 000 years the red sea has remained open to the gulf of aden with cross sectional areas at times of glacial maxima about 2 of that today vi the minimum channel widths connecting the red sea to the gulf of aden at times of lowstand occur south of the hanish sill the channels are less than 4 km wide and remain narrow for as long as local sea levels are below 50 m this occurs for a number of sustained periods during the last two glacial cycles and earlier vii periods suitable for crossing between africa and arabia without requiring seaworthy boats or seafaring skills occurred periodically throughout the pleistocene particularly at times of favourable environmental climatic conditions that occurred during times of sea level lowstand

ice 3g a new global model of late pleistocene deglaciation based upon geophysical predictions of post glacial relative sea level change a new high resolution global model of late pleistocene deglaciation is inferred on the basis of geophysical predictions of postglacial relative sea level variations in which the ice ocean solid earth interaction is treated in a gravitationally self consistent fashion for the purpose of these analyses the radial viscoelastic structure of the planet is assumed known on the basis of previously published sensitivity tests on solutions of the forward problem only radiocarbon controlled relative sea level histories from sites that were actually ice covered with one or two additions are employed to constrain the model leaving relative sea level rsl data from sites that were not ice covered to be employed to confirm its consistency results for these confirmatory analyses are reported elsewhere here the new deglaciation model referred to as ice 3g is compared to previous models derived by several independent means and tested against a number of additional observations other than sea level histories including geologically controlled retreat isochrones oxygen isotope data from deep sea sedimentary cores and coral terrace elevations the latter two observations strongly constrain the net sea level rise that has occurred since the onset of deglaciation and therefore the mass of ice that melted during the last glacial interglacial transition

constraints on the late weichselian ice sheet over the barents sea from observations of raised shorelines abstract direct evidence for late weichselian grounded glacier ice over extensive areas of the barents sea is based largely on indirect observations including elevations of old shorelines on svalbard and arguments of isostatic rebound such isostatic models are discussed here for two cases representing maximum and minimum ice sheet reconstructions in the former model the ice extends over the kara sea whereas in the latter the ice is limited to the barents sea and island archipelagos comparisons of predictions with observations from a number of areas including spitsbergen nordaustlandet edgeoya kong karls land franz josef land novaya zemlya and finnmark support arguments for the existence of a large ice sheet over the region at the time of the last glacial maximum this ice sheet is likely to have had the following characteristics conclusions that are independent of assumptions made about the earth s rheological parameters i the maximum thickness of this ice was about 1500 2000 m with the centre of the load occurring to the south and east of kong karls land ii the ice sheet extended out to the western edge of the continental shelf and its maximum thickness over western spitsbergen was about 800 m iii to the north of svalberg and frans josef land the ice sheet extended out to the northern shelf edge iv retreat of the grounded ice across the southern barents sea occurred relatively early such that this region was largely ice free by about 15 000 bp v by 12 000 bp the grounded ice had retreated to the northern archipelagos and was largely gone by 10 000 bp vi the ice sheet may have extended to the kara sea but ice thicknesses were only a fraction of those proposed in those reconstructions where the maximum ice thickness is centered on novaya zemlya models for the palaeobathymetry for the barents sea at the time of the last glacial maximum indicate that large parts of the barents sea were either very shallow or above sea level providing the opportunity for ice growth on the emerged plateaux as well as on the islands but only towards the end of the period of fennoscandian ice sheet build up

smooth or oscillating late holocene sea level curve evidence from the palaeo zoology of fixed biological indicators in east australia and beyond abstract the nature of late holocene sea level change has important palaeo environmental implications for the understanding of past and present coastal oceanic and climatic systems this study develops a fixed biological indicator fbi method based on tubeworm barnacle assemblages in order to construct a late holocene sea level curve for south east australia it also compares changes within and between mid latitude regions of the southern hemisphere using the palaeo biology of inter tidal sub fossils that have provided time elevation data covering the past 5000 years five sites from around the mouth of the port hacking estuary 29 km south of sydney are described in detail the results suggest that rather than relative sea level describing a stable or smoothly falling pattern from a maximum of 1 0 m above present over the last 5000 years on the southeast australian coast there have been complex movements from a maximum of over 1 5 m with at least one marked fall between 3500 and 3400 yr bp and the possibility of a small positive oscillation around 1900 yr bp furthermore changes in the inter tidal species at our sites suggest that there was a period between 4300 and 2800 years where ocean temperatures were warmer than present our port hacking findings are compared with other studies from the east coast of australia as well as the pacific islands and brazil evidence from each location suggests a broad similarity in the timing of environmental events and marine fluctuations across an expanse of the southern hemisphere are such similarities coincidental or part of mechanisms common to mid latitude southern hemisphere regions

holocene sea levels in oceanic islands implications for the rheological structure of the earth s mantle abstract relative sea levels in oceanic islands that are situated sufficiently far from glaciated regions were studied in relation to the rheological structure of the earth s mantle the local hydro isostatic adjustment associated with the mantle flow from the oceanic side to an inland side depends on the size of the island the effective upper mantle viscosity and the elastic plate thickness the relative sea level has a significant dependence on the upper mantle rheology for islands with a radius larger than 10 km but it is almost independent of the upper mantle rheology for islands with a radius less than 10 km in other words the observed sea level changes in such small islands follow the global isostatic adjustment which depends strongly on the lower mantle viscosity in fact the relative sea levels in small oceanic islands impose important constraints on the lower mantle viscosity on the other hand the effective upper mantle viscosity and the elastic plate thickness are determined by analyzing the relative sea levels for islands greater than 10 km the observed sea level curves in japan and new zealand are consistent with the effective viscosity of the upper mantle equal to 2 to 6 10 21 poises the effective elastic plate thickness for japan and new zealand is estimated to be less than 50 km and greater than 100 km respectively the thickness of the lithosphere obtained by sea level curves in japan and new zealand is compatible with the results obtained by seismological studies

suppression of earthquakes by large continental ice sheets the interior regions of antarctica and greenland are aseismic no earthquake larger than body wave magnitude 4 5 5 0 is known for either except along coastal zones or continental shelves here i advance an explanation for this lack of seismic activity in terms of pressure effects produced by the continental ice sheets that mantle both continents

late weichselian to early holocene litho and biostratigraphy in the devil s hole area central north sea and its relation to glacial isostasy the 6 m long british geological survey vibrocore 56 01 170 from the devil s hole area central north sea comprises glaciomarine and marine sediments of late weichselian and holocene age besides the foraminiferal pollen and ams 14c data presented in this study amino acid and ostracod data exist for the core the accumulation of the sediment in the core began ca 15 7 14c ka bp on an erosional surface on overconsolidated saalian sediment when the lower part of the core facies 1 accumulated the core area is interpreted to have been around 40 m lower than present this interpretation is based on two assumptions first that the sediment is now ca 20 m above the global sea level at the time of deposition and second that the marine microfaunal content reflects a water depth of about 20 m at that time crustal downflexure caused by late weichselian glacial loading of the core area is considered as the most plausible explanation of this difference glacial overriding would also explain the overconsolidation of the underlying saalian sediment the erosional surface on the saalian sediment and the absence of weichselian sediment older than ca 15 7 ka bp at the core site indications of a regressional trend with a minimum age of 12 1 ka bp support the suggestion that the devil s hole area was glaciated during the weichselian as the fall in sea level at that time probably reflects local isostatic rebound

stress relief buckles in the mcfarland quarry ottawa six quarry floor buckles in a west end ottawa bedrock quarry are described and a semi quantitative estimate of the stress field is inferred from them the maximum principal stress component is hori

holocene glacial rebound and sea level change in nw europe summary observations of late pleistocene and holocene sea level change relative to the crust exhibit very considerable variations across nw europe in consequence of the response of the earth s crust to the deglaciation of fennoscandia and of the water added to the oceans from the melting of all late pleistocene ice sheets inversion of sea level observations from a site near the centre of the fennoscandian ice sheet and from three sites located beyond the margin of the ice sheet at the time of maximum glaciation yield a range of plausible models for the earth s response and for the ice models further constraints on this range of models is placed by a comparison of observed sea levels with predicted values at other sites near the former ice sheet margins the resulting mantle parameters are upper mantle viscosity 3 5 x 10 pa s lower mantle viscosity 2 7 x loz1 pa s lithospheric thickness 100150 km these values represent effective parameters that describe the response of the earth to surface loading of short to intermediate wavelengths on a time scale of 104yr the lower mantle viscosity is poorly constrained but the marked increase from upper to lower mantle is a characteristic of all plausible solutions the inversion places a constraint on the total volume of ice in the fennoscandian ice sheet such that the equivalent sea level rise from this contribution is about 13 14 m a less well determined constraint of about 10 m equivalent sea level rise is suggested for the barents kara ice sheet the inversion also indicates that a small amount of melt water from ice sheets far away from europe continued to be added into the oceans during late holocene time so as to raise the equivalent sea level by about 3 m during the past 6000 yr consistent with similar inversions of data from sites in the australian and pacific regions

integration of core logging and drilling data in modern reefal carbonates to improve core location and recovery estimates iodp expedition 310 palaeoclimate and sea level studies commonly rely on interpretations based on depth the location and quantity of core recovered during a drilling expedition has direct implications for subsequent applications of core measurements a key objective of integrated ocean drilling program iodp expedition 310 is to establish the course of postglacial sea level rise for tahiti in the south pacific for which assigning the correct depth to recovered core is fundamental by convention core is placed at the top of the core barrel run from which it was collected unless core recovery is 100 this results in depth errors that are inversely proportional to the recovery the difficulties of locating core are compounded for the tahiti boreholes where primary cavities in the carbonate reef successions are frequently present only through the integration of core with continuous geophysical measurements of the borehole can accurate depth positioning be achieved high resolution optical and acoustic images of the borehole wall allow effective visual correlation of the core and logging datasets the final integrated depths form the underlying framework for all subsequent scientific analyses of recovered core employing evaluations that rely on depth furthermore the integration process allows true core recoveries to be accurately estimated

sediment facies and holocene deposition rate of near coastal fluvial systems an example from the nobi plain japan abstract floodplains are a major component of present near coastal fluvial systems that have evolved in response to postglacial changes in climate and sea level knowledge of sedimentary facies and deposition rates on a centennial to millennial time scale is required for considering floodplain evolution two cores ap1 and ap2 were acquired from an abandoned channel of the ibi river and its natural levee on the nobi plain central japan sediment facies analysis electrical conductivity and radiocarbon dating of borehole samples showed that in both cores organic rich dark gray floodbasin mud overlies deltaic deposits dating to after approximately 3200 years calibrated radiocarbon age cal bp in relation to delta progradation the accumulation of floodbasin mud continued at the both sites until about 400 cal bp around 400 cal bp the mud was eroded by the overlying channel sand and gravel at ap1 and was covered by fine grained natural levee deposits at ap2 with an abrupt contact this timing is concordant with the historical record of avulsion of the ibi river during the keicho era ad 1596 1615 averaged aggradation rates at the ap1 and ap2 sites were approximately 2 2 and 3 2 mm yr respectively faulting related subsidence along the western edge of the plain has influenced these rates by creating accommodation averaged deposition rates differed greatly between the floodbasin and the levee suggesting that rapid aggradation of the natural levee also occurred on a centennial to millennial scale these empirical data may be useful for testing models of the architecture and evolution of near coastal fluvial systems

glacial geomorphic features in the northern barents sea direct evidence for grounded ice and implications for the pattern of deglaciation and late glacial sedimentation

simulations of northern hemisphere ice sheet retreat sensitivity to physical mechanisms involved during the last deglaciation a 3 dimensional thermomechanical ice sheet model is used to simulate the evolution of the geometry of northern hemisphere ice sheets through the last deglaciation the ice sheet model is forced by a time evolving climatology provided by the linear interpolation through time of climate snapshots simulated by the lmd5 3 atmospheric general circulation model agcm at different periods of the last deglaciation 21 15 9 6 and 0 kyr bp the agcm is driven by insolation atmospheric co2 content ice sheet configuration and sea surface temperatures although our approach is able to produce the complete continental ice retreat our simulated deglaciation presents a phase lag with reconstructions based on observational evidences this suggests that physical mechanisms related to climate forcing and or ice sheet internal dynamics are not properly represented the influence of millennial scale forcing feedback mechanisms between ice sheet elevation and surface mass balance and parameterization of the ice flow is also tested through a set of sensitivity experiments the rapid variability has a strong impact on the evolution of the ice volume because of nonlinear effects in temperature mass balance relationships fennoscandia appears to be strongly sensitive to the small scale ice sheet instability both ice sheets are to some extent sensitive to an increased basal sliding

the analysis and prediction of lateral instability in highly stressed near surface rock strata the potential for lateral instability of highly stressed near surface sedimentary rocks such as the paleozoic deposits of southern ontario and western new york state is investigated analytically the minimum magnitude of the in situ stress required for a pressure ridge to form is easily computed once values are obtained for the stratum thickness and short term young s modulus the weight of overburden and the residual friction with the over and underlying material consideration is also given to the increased likelihood of instability associated with excavations of different widths and depths keywords rock excavations quarries instability pressure ridges mechanisms

the melting history of the late pleistocene antarctic ice sheet spatial and temporal variations in the sea levels of the past 20 000 years around the globe place constraints on the melting history of the major late pleistocene ice sheets the antarctic ice sheets provided a significant contribution to the sea level rise at a rate that was approximately synchronous with the melting of the laurentide ice sheet except for the interval 9 000 6 000 years ago when it may have lagged behind minor melting of the antarctic ice sheet continued throughout the holocene

a below the present late holocene relative sea level and the glacial isostatic adjustment during the holocene in the malay peninsula abstract this study has reconstructed the holocene relative sea level history in the relatively tectonically stable malay peninsula with two specific objectives quantifying the sea level indicative meanings of mangrove sediments and producing new high quality sea level index points in this study a wetland on the east coast of the peninsula was extensively surveyed the elevational relationship between habitat zones and their pollen and diatom assemblages was established and a number of indicative meanings were precisely quantified for this wetland this quantified relationship is extrapolated to other coastal sites of the peninsula for re calibration of previously published mangrove based sea level data the reconstructed sea level history from the new and re calibrated data demonstrates a period of rapid sea level rise at a rate of 15 8 3 9 mm a between 10 500 cal a bp at 35 0 4 3 m and 9000 cal a bp at 14 2 1 6 m the rate of rising sea level was gradually reduced to zero from 9000 to 5000 cal a bp and by the end of this period the relative sea level reached a highstand of c 3 3 0 2 m over the past 5000 years relative sea level fell to its lowest point at 0 6 0 1 m by 800 cal a bp this far field sea level history has been driven by the global ice volume change and glacial isostatic adjustment and it matches well with the modelled ice volume equivalent sea level

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

holocene relative sea level change and deglaciation on alexander island antarctic peninsula from elevated lake deltas abstract field data constraining the rate and spatial pattern of deglaciation and relative sea level rsl change on the antarctic peninsula ap are relatively sparse but are needed to improve regional ice sheet and rsl change models and contribute to better model predictions of future sea level rise we investigated the geomorphology sedimentology and quartz fraction single aliquot regeneration optically stimulated luminescence sar osl geochronology of elevated deltas around two epishelf lakes ablation lake al and moutonnee lake ml alexander island antarctic peninsula al and ml are dammed by george vi ice shelf and maintain a direct hydraulic connection to the sea hence their water levels are controlled by changes in rsl our aim was to provide new terrestrial constraints on rsl and deglaciation for the southern ap by comparing the formation processes age and altitude of the al and ml deltas with 1 existing rsl curves for the ap 2 isostatically coupled ap ice sheet models and 3 existing ap deglaciation history and sar osl ages from elevated deltas around the nearby inland hodgson lake hl although there was insufficient quartz in the ml samples for sar osl dating the 4 6 0 4 ka sar osl age of the elevated delta at al represents the last time active deltas were forming higher than present day lake level and implies 1 a fall in rsl of up to 14 4 m since the mid holocene in this part of alexander island which is consistent with existing field based rsl chronologies for the ap 2 relatively smaller ice masses than suggested by some but not all isostatically coupled ice sheet models since the mid holocene and 3 significant mid holocene thinning of the ap ice sheets which is consistent with regional sediment core data and cosmogenic exposure ages and the 4 4 0 7 ka sar osl age of the lowermost hl delta

holocene relative sea level history of novaya zemlya russia and implications for late weichselian ice sheet loading abstract we present six new radiocarbon dated emergence curves that provide a detailed record of postglacial emergence of northern novaya zemlya and ages which constrain the emergence of vaygach island in the southern archipelago radiocarbon ages on hiatella sp from a lateral moraine in russkaya gavan and abundances of foraminifea in a marine core from nordenskiold bay 300 km south of our study area indicate that coastal deglaciation occurred prior to 10 000 cal yr b p however postglacial emergence commenced 7000 cal yr b p with stabilization of global sea level the total emergence is 13 11 m above sea level asl with apparent uplift rates of 1 2 mm yr for the past 2000 yr indicating modest glacier loads 11 000 cal yr b p deglaciation or both the isobase pattern showing no east west tilt across novaya zemlya and offshore moraines suggest a separate ice dispersal center over novaya zemlya for the later stages of the late weichselian glacial cycle and possibly earlier

glacial rebound and relative sea level variations a new appraisal summary late pleistocene and holocene changes in sea level at technically stable shorelines contain information on the melting history of the ice sheets and on the response of the earth to changes in surface loads on time scales of 104yr some separation of parameters defining the ice loads and the earth s response can be achieved by examining sea level change at different sites around the world and at different epochs this paper examines the mathematical requirements for obtaining satisfactory solutions for the sea level equation rather than emphasizing results for the earth s response to the surface loads an examination of the equation expressing the sea level variation on a viscoelastic earth indicates that careful consideration needs to be given to both the definition of the ice load and the geometry of the redistributed water load if geophysically significant earth response parameters are to be deduced from observations of relative sea level the spectrum of the 5 x 5 area mean description of the ice load widely used in glacial rebound studies contains significant power at high degrees n 30 and can result in substantial spatial variations in sea level unless a thick lithosphere is introduced in the earth s response function a smoothed 1 1 description of the ice model avoids these high degree oscillations in relative sea level and produces satisfactory sea level results without requiring a thick lithosphere at far field sites the holocene sea levels are sensitive to the earth s response to the meltwater loading in the vicinity of the site and a high degree spatial resolution of coastline geometry is required to model the mantle flow driven by the differential loading about the site at some sites convergence of the solution to the sea level equation is not obtained even when the solution is expanded to degree 180 convergent solutions at lower degrees can be achieved by introducing earth models with a moderately thick lithosphere if high resolution ice and meltwater load models are not used then the tendency will be to overestimate the effective elastic thickness of the lithosphere estimates of mantle viscosity are also of questionable value if these high resolution models are not used a preliminary examination of sea levels at sites in both the near and far field places an upper limit of about 50 80 km on the effective lithospheric thickness these sea level observations are also consistent with an upper mantle viscosity of about 1021 pas with a lower mantle viscosity in the range of 1021 1023pa s

the last glacial maximum on spitsbergen svalbard most scientists have concluded previously that the west coast of spitsbergen svalbard remained ice free during the late weichselian between 25 000 and 10 000 yr b p we conclude that the glaciation was more extensive terraces that were postulated to have been ice free are covered by a thin late weichselian till sudden drop in the marine limit and basal radiocarbon dates of raised glaciomarine sediments demonstrates that the glaciers in the main fjords isfjorden and van mijenfjorden terminated west outside of the fjord mouths basal radiocarbon dates from glaciomarine clay above till in cores from the continental shelf west of spitsbergen yielded ages of about 12 500 yr b p from which we conclude that the ice extended to the shelf edge based on the extent of amino acid diagenesis in radiocarbon dated molluscs the duration of the maximum extension of the late weichselian glaciation was short certainly less than 10 000 years during the ice free period preceding that glaciation at least back to 40 000 yr b p the glaciers on svalbard were not significantly larger than at present as shown by marine deposits close to the glacier snouts many radiocarbon dates place deglaciation of the outer coast at about 12 500 yr b p at about 10 000 yr b p the rest of the archipelago rapidly became ice free

glacial isostatic adjustment and the free air gravity anomaly as a constraint on deep mantle viscosity summary a gravitationally self consistent theory for relative sea level variations forced by pleistocene deglaciation events is employed to explore the extent to which rsl and free air gravity observations together constrain the viscosity of the mantle beneath the seismic discontinuity at 670 km depth a trade off is revealed between errors in the assumed deglaciation history and errors in the inferred value of the viscosity of the lower mantle taking full account of such uncertainty plausible values of the viscosity beneath the transition region are bounded above by 1023 poise cgs units the preferred value is at least a factor of 2 lower than this and is strongly constrained by the observed free air gravity anomaly over hudson bay the calculations described in detail here show for the first time that the relatively large gravity anomalies observed over sites of wurm wisconsin deglaciation do not require any pronounced increase of mantle viscosity with depth in order to explain them

calibration of the c 14 timescale over the past 30 000 years using mass spectrometric u th ages from barbados corals uranium thorium ages obtained by mass spectrometry from corals raised off the island of barbados confirm the high precision of this technique over at least the past 30 000 years comparison of the u th ages with 14c ages obtained on the holocene samples shows that the u th ages are accurate because they accord with the dendrochronological calibration before 9 000 yr bp the 14c ages are systematically younger than the u th ages with a maximum difference of 3 500 yr at 20 000 yrbp the u th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration

liquefaction features on the fraser delta evidence for prehistoric earthquakes sand dykes and sills and vented sand boils on the fraser river delta and adjacent serpentine river floodplain in southwestern british columbia record one or more major liquefaction events the source of the dykes is a shallow subsurface saturated sand unit that was deposited in foreslope and distributary channel environments during holocene progradation of the fraser delta the dykes cut steeply through a crust of delta topset muds and locally flatten out as sills in overlying peaty sediments at two sites evidence was found for venting of sand onto a subaerial or intertidal surface liquefaction and upward movement of sand and water locally deformed the intruded sediments causing some subsidence and uplift of the delta surface all observed liquefaction features are younger than ca 3500 bp and at least some are younger than 2400 bp it is not clear however whether they formed during one or several separate events a review of possible causes suggests that the liquefaction features probably are seis

late pleistocene and holocene sea level change in the australian region and mantle rheology summary spatial and temporal variations in sea level are produced by the melting of the late pleistocene ice and by the earth s response to the redistribution in surface loads by examining different parts of the sea level curves of the past 20 000 yr from geographically widely distributed regions it becomes possible to constrain models of the melting history of the ice sheets and of the earth s rheology observations from sites away from the former arctic ice sheets such as the australian and south pacific region are particularly important for constraining the total meltwater volumes added into the oceans in the past 20 000 yr and the rates at which this occurred these observations indicate that the antarctic ice sheets provided a significant contribution to the sea level rise at a rate that was approximately synchronous with the melting of the laurentide ice sheet except for the interval 9000 6000 yr ago when it may have lagged behind minor melting of the antarctic ice sheet appears to have continued throughout the late holocene differential observations of the late holocene sea level change recorded at sites in the same region are particularly useful for estimating parameters describing the earth s non elastic response to surface loading the effective parameters used here are a lithospheric thickness an upper mantle viscosity and a lower mantle viscosity describing the response below 670 km depth with the observations used here it is not possible to separate the lithospheric thickness h from the upper mantle viscosity and the viscosity results are based on the assumption that 50 h 100 km neither do these observations provide a resolution of the depth dependence of viscosity in the upper mantle and the resulting estimates are effective parameters only differential sea levels along continental margins and along the shores of large gulfs and bays constrain the effective upper mantle viscosity to be about 1 2 1020 pa s 1 while differential values from islands of different sizes are suggestive of a somewhat lower value the lower mantle taken to be below 670 km depth viscosity is about two orders of magnitude greater than this the estimated ice and rheological models explain many of the holocene sea level observations throughout the australian and southern pacific region the tilting of continental margins as exemplified by observations of variable amplitudes of the holocene high stands and the variable times at which sea levels first reached their present level along the north queensland coast and great barrier reef is well represented by these models differential holocene sea levels observed along the narrow spencers gulf of south australia are also well explained by the models and in neither case is it necessary to invoke tectonic motions predicted late holocene sea levels at small to medium sized islands are characterized by small amplitude high stands that reached their maximum values about 4000 2000 yr ago consistent with observations from the society cook and tuamotu islands

autochthonous block fields in southern norway implications for the geometry thickness and isostatic loading of the late weichselian scandinavian ice sheet the consistent geographical and altitudinal distribution of autochthonous block fields mantle of bedrock weathered in situ and trimlines in southern norway suggests a multi domed and asymmetric late weichselian ice sheet low gradient ice sheet profiles in the southern baltic region in the north sea and along the outer fjord areas of southern norway are best explained by movement of ice on a bed of deforming sediment although water lubricated sliding or a combination of the two may not be excluded the ice thickness distribution of the late weichselian scandinavian ice sheet is not in correspondence with the modern uplift pattern of fennoscandia early holocene crustal rebound was apparently determined by an exponential glacio isostatic rise later however crustal movements appear to have been dominated by large scale tectonic uplift of the fennoscandian shield centred on the gulf of bothnia the region of maximum lithosphere thickness

glacial rebound of the british isles iii constraints on mantle viscosity summary observations of sea level change since the time of the last glacial maximum provide important constraints on the response of the earth to changes in surface loading on time scales of 103 104 years this response is conveniently described by an effective elastic lithospheric thickness and effective viscosities for one or more mantle layers considerable trade off between the parameters describing these layers can occur and different combinations can give rise to comparable predictions of sea level change in particular the trade off between lithospheric thickness and upper mantle viscosity can be important and for any reasonable value for the lithospheric thickness a corresponding mantle viscosity structure can be found that gives a plausible comparison of sealevel predictions with observations in particular thin lithosphere models will lead to low estimates for the upper mantle viscosity while thick lithosphere models lead to high viscosity values however either solution may represent only a local minimum in the model parameter space and may not correspond to the optimum solution it becomes important therefore that in the inversion of observational data a comprehensive search is conducted throughout the entire model parameter space to ensure that the solution identified does indeed correspond to the optimum solution the sea level data for the british isles lend themselves well to such an inversion because of the relatively high quality of the data the good geographic distribution of the data relative to the former ice sheet and reasonable observational constraints on the dimensions of the former ice sheet and on its retreat furthermore because of the contribution to the sea level signal from the distant ice sheets as well as from the melt water load the observational data base for the region also has some resolving power for the viscosity of the deeper mantle the parameter space explored is defined by up to five mantle layers the lithosphere of effective elastic thickness d and a series of upper mantle layers i 2 4 extending down to depths of 200 400 and 670 km respectively each of viscosity qi and a lower mantle layer of viscosity qlm extending down to the coremantle boundary the range of parameters explored is 30 d i 120 km 3 x loi9 iqi

sea level controls on the post glacial development of the great barrier reef queensland abstract the central great barrier reef is situated on a 125 km wide continental shelf with a shallow shelf break at ca 70 m in consequence the earlier post glacial reef tract was confined to a narrow fringing belt along the present upper slope and outer shelf the reef province only started to assume its modern dimensions after ca 10 ky b p when sea level stabilised at depths around 28 m reef growth since 18 ky b p has been controlled by the episodic nature of the post glacial transgression being related to shorelines s8 to s1 developed at estimated eustatic depths and ages of 114 m 18 ky b p 88 m 17 ky b p 75 m 15 ky b p 56 m 12 ky b p 45 m 11 ky b p 39 m 10 ky b p 28 m 9 5 ky b p 23 m 9 ky b p 9 m 7 5 ky b p and 0 m 6 5 ky b p rates of sea level rise as high as 12 m ky 1 occurred between stillstands outpacing coral growth response and resulting in many mid outer shelf reefs being drowned in situ

multiple late holocene earthquakes along the reelfoot fault central new madrid seismic zone the reelfoot fault is an east vergent reverse fault underlying the lake county uplift a low amplitude late holocene anticline bordered on the east by the 32 km long reelfoot scarp fluvial deposits across the scarp define an 8 m high east facing monocline most near surface deformation along the scarp is accommodated via folding rather than faulting we interpret the scarp as a fault propagation fold developed over a wcst dipping reverse fault interpreted from shallow seismic reflection data trench exposurcs provide evidence for three episodes of deformation along the reelfoot fault within thc past approximately 2400 years between a d 780 and 1000 between a d 1260 and 1650 and during a d 1812 our best estimate of the average recurrence interval for deformation along the scarp is 400 500 years each episode of deformation had a slightly different style the third most recent event produced a small graben a few tens of centimeters deep in the hanging wall of the reverse fault the second most recent earthquake produced about 1 3 m of throw in the graben as well as folding along the updip projection of the reverse fault and development of the scarp thesc relations suggest that graben development increased through time concomitant with growth of the monocline or that the events are of different magnitude the 1811 1812 episode of deformation produced abundant liquefaction prominent folding of fluvial strata along the scarp and minor faulting in the graben

pleistocene sea levels and tectonic uplift based on dating of corals from sumba island indonesia we collected and dated fossil corals from the uplifted reef tracts of sumba island mass spectrometry tims and ams was used to obtain reliable and precise radiochronological results it is possible to identify outcrops corresponding to major sea level high stands isotope stage 1 starting at 7 1 kyr bp 5a c a 86 kyr bp 5c c a 105 kyr bp 5e between 119 and 132 kyr bp and 9 c a 305 kyr bp the radiochronological data are thus broadly consistent with the timing of sea level fluctuations predicted by the astronomical theory of paleoclimates comparison with similar data from other terrace sequences and from benthic 18o records indicates that the average tectonic uplift rate at cape laundi sumba is on the order of 0 2 0 5m kyr the lowest values 0 3m kyr lead to the build up of polycyclic topographic terraces in which it is possible to find corals grown during different interstadial or even interglacial times

glacial rebound of the british isles ii a high resolution high precision model summary observations of ice movements across the british isles and of sea level changes around the shorelines during late devensian time after about 25 000 yr bp have been used to establish a high spatial and temporal resolution model for the rebound of great britain and associated sea level change the sea level observations include sites within the margins of the former ice sheet as well as observations outside the glaciated regions such that it has been possible to separate unknown earth model parameters from some ice sheet model parameters in the inversion of the glaciohydro isostatic equations the mantle viscosity profile is approximated by a number of radially symmetric layers representing the lithosphere the upper mantle as two layers from the base of the lithosphere to the phase transition boundary at 400 km the transition zone down to 670 km depth and the lower mantle no evidence is found to support a strong layering in viscosity above 670 km other than the high viscosity lithospheric layer models with a low viscosity zone in the upper mantle or models with a marked higher viscosity in the transition zone are less satisfactory than models in which the viscosity is constant from the base of the lithosphere to the 670 km boundary in contrast a marked increase in viscosity is required across this latter boundary the optimum effective parameters for the mantle beneath great britain are a lithospheric thickness of about 65 km a mantle viscosity above 670 km of about 4 5 lo2 pa s and a viscosity below 670 km greater than 4 x lo2 pas

sea level change along the french atlantic and channel coasts since the time of the last glacial maximum abstract holocene sea level change along the french atlantic and english channel coast is not uniform because of the response of the crust to the changing ice and water loads in late pleistocene and holocene time the pattern of the spatial variability is a north south trend of decreasing sea levels levels at any time this results primarily from the isostatic response to the melting of the fennoscandian ice sheet superimposed upon this is a mainly east west trend resulting from the isostatic response of the crust to the addition of the meltwater into the atlantic ocean the combined effect is that at any time sea levels vary spatially along this coastline by amounts that are predicted to reach 20 m from the time of the last glacial maximum to about 10 000 radiocarbon yr ago about 15 m at 8000 yr ago and about 10 m at 6000 yr ago thus observations of past sea levels should not be combined into a single sea level curve unless first corrected for the glacio hydro isostatic factors alternatively the data should only be used to construct regional curves for relatively short sections of the coastline such as pas de calais and picardie normandie cotes du nord finistere or the vendee and charente maritime region even within such constrained regions the spatial variability may still be of the order of a few meters analysis of the observational data by region indicates that major oscillations in sea level are unlikely to have occurred that levels at no location exceeded the present mean sea level and that there may have been a small 3 m increase in eustatic sea level over the past 6000 yr palaeoshorelines and palaeo water depths for the english channel and the atlantic coast shelf have been predicted using the isostatic and eustatic models and the results indicate that in situ marine deposits older than 6000 7000 yr are unlikely to be found along many sections of the present coastline

the present rate of uplift of fennoscandia implies a low viscosity asthenosphere the rate of displacement in fennoscandia has been intensively discussed for many years it is now widely accepted to be an isostatic response of the glacial history of the area the earth s present response to deglaciation in fennoscandia is simulated using a three dimensional 3d viscoelastic model in which the asthenosphere and mantle viscosity are allowed to vary so that the maximum rate of present uplift matches its observed value the deglaciation history is considered to be known and the c14 datings are converted to sidereal years the pattern of the present uplift gives a firm match with the observed data when a low viscosity asthenosphere is introduced assuming a 15 000 years load cycle i e the glacier was applied to the surface for 15 000 years before the melting started the best fitting earth viscosity model is a 1024 nm lithosphere overlying a 75 km thick 2 0 1019 pas asthenosphere and a 1 2 1021 pas mantle the simulations suggest a remaining maximum uplift of 40 m

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

the influence of dynamically supported topography on estimates of te abstract the effective elastic thickness t e of continental lithosphere can be estimated from the relationship between gravity and topography in the spectral domain two methods have been used one of which depends on the coherence between bouguer gravity anomalies and topography whereas the other uses the transfer function commonly known as the admittance between the free air gravity and topography the two methods give estimates of t e which differ by as much as an order of magnitude in those continental regions where variations in elevation are small this problem has led to much controversy an important concern is the extent to which estimates of t e are affected by dynamically maintained gravity and topography arising from mantle convection and postglacial recovery unlike elastically supported anomalies these processes can generate gravity and topographic long wavelength 500 km anomalies if such anomalies are modelled as being supported by elastic forces the resulting values of t e are overestimated often by a large amount

the influence of rock strength and abrasive mineral content on the cerchar abrasive index abstract the cerchar abrasive index is based on a simple test and is widely used to assess the abrasiveness of rocks detailed examination of the test has shown that the index is largely influenced by the rock strength and only partially by the rock abrasiveness the standard test was found to be incapable of providing accurate indices for rocks of low relative abrasiveness and a modification to the test is presented to overcome this problem the interpretation of the test results has been extended to enable calculation of the specific wear rate which is a more precise measure of the abrasiveness of materials

coral reef sedimentation on rodrigues and the western indian ocean and its impact on the carbon cycle coral reefs in the southwest indian ocean cover an area of ca 18530 km2 compared with a global reef area of nearly 300000 km2 these regions are important as fishing grounds tourist attractions and as a significant component of the global carbon cycle the mass of calcium carbonate stored within holocene neritic sediments is a number that we are only now beginning to quantify with any confidence in stark contrast to the mass and sedimentation rates associated with pelagic calcium carbonate which have been relatively well defined for decades we report new data that demonstrate that the reefs at rodrigues like those at reunion and mauritius only reached a mature state reached sea level by 2 3 ka thousands of years later than most of the reefs in the australasian region yet field observations show that the large lagoon at rodrigues is already completely full of carbonate detritus typical lagoon depth less than 1 m at low spring tide the presence of aeolian dunes at rodrigues indicates periodic exposure of past lagoons throughout the pleistocene the absence of elevated pleistocene reef deposits on the island indicates that the island has not been uplifted most holocene reefs are between 15 and 20 m in thickness and those in the southwest indian ocean appear to be consistent with this observation we support the view that the co2 flux associated with coral reef growth acts as a climate change amplifier during deglaciation adding co2 to a warming world southwest indian ocean reefs could have added 7 10 to this global flux during the holocene

a study of rock abrasivity and tool wear in coal measures rocks this paper examines the relations between cerchar abrasivity index cai and petrographic properties of coal measures rocks in the zonguldak coal basin turkey in this study petrographic properties and abrasivity indices of 29 sedimentary rock samples were determined and the values of cai and petrographic analysis results were compared a good linear relationship between cai and average quartz grain size parameters was found the test results also showed that abrasivity was affected by the mineralogical composition cement type degree of cementation quartz content and average quartz grain size it was found that abrasivity of rock was decreased by the low grade of cementation between abrasive minerals cai values and petrographic properties were used to estimate tool consumption in underground works in the zonguldak coal basin it was observed that when cai values increased tool consumption increased

hydro isostasy and the sea level isobase of 5500 b p in north queensland australia abstract previous studies of holocene sea level in north queensland have been based on a variety of sea level related deposits with interpretations of mid holocene levels ranging from near zero up to 4 m above present we report data from 8 carefully controlled new sites located from the palm group northwards and extending into the gulf of carpentaria field evidence is from coral reef flats and prograded coastal deposits the highest sea level on inner shelf islands and mainland coast occurred 5500 yrs ago the results of this and of certain previous studies are reduced to a common reference surface or isobase which varies systematically in elevation across the region the isobase correlates strongly with predicted hydro isostatic deformation caused by postglacial sea level rise

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

post glacial relative sea level history of northwestern spitsbergen svalbard the late weichselian and holocene raised beach sequences on northwestern spitsbergen provide a detailed record of sea level oscillations during the last deglacial hemicycle initial emergence commenced at 13 ka coincident with local deglaciation and until 10 5 ka was characterized by a relative slow rate of emergence 1 5 to 5 m ka interrupted by minor stillstands or transgressions associated with possible glacier re advances the orientation of paleo spits and the paucity of whale remains at the late weichselian marinelimit indicate that the prevailing westerly fetch was dampened by a semi permanent sea ice cover allowing long shore drift to predominate a period of accelerated emergence 15 to 30 m ka between 10 5 and 9 ka is correlative with rapid deglaciation of fiords the middle and late holocene is characterized by two brief transgressions one between 6 5 and 5 0 ka that did not exceed 7 m asl and a present probable slow rise in sea level that commenced 2 to 1 ka the strandline tilts in northwestern spitsbergen and the pattern and rate of emergence on svalbard indicate that the maximum glacier loads during the late weichselian were centered on nordaustlandet and on the central and eastern part of the archipelago northwestern and southwestern spitsbergen were marginal to glacial loading and were deglaciated early 13 ka which is presently incompatible with maximum ice sheet extent and the timing and position of deglacial margins recently reconstructed for the barents sea and svalbard mountain ranges and large fiords probably confined major outlet glaciers to the central part of the archipelago preventing inundation of much of western spitsbergen by an inferred large ice sheet based in eastern svalbard and the barents sea

very high energy sedimentation supratidal hurricane deposits and mid holocene highstand on carbonate platforms andros bahamas an alternative view abstract twenty eight 14 c dates were obtained from 90 cores drilled through the tidal flats of western andros island a large area 2000 km 2 mostly covered by mangroves and stromatolitic deposits these dates are correlated with location of the samples sedimentological description position of the samples at the time of deposition and their present day sedimentological position measurements were made on bulk algal sediments and location of the relative paleo sea level is inferred from paleobathymetric reconstructions on the basis of 14 c dates i conclude that the whole area was flooded about 5000 years bp and then was covered by the subtidal greyish mud facies rich in peneroplids in the area of deep creek north of the study area pelican creek and wide opening southeast of the study area the level of this paleo great bahama bank sea continued to rise until 3500 years bp and then slowly fell asymptotically toward the present day level thick hurricane marks aragonitic lime mud with didemnids spicules several cm thick previously defined as hurricane trails can be observed throughout the cores from 2000 years bp onwards from 2000 years bp onwards it seems that the modern physiography was already established including tidal estuaries channels and stromatolite bearing swamps paleogeographic maps and sections have been drawn and accumulation rates calculated in the various sedimentological zones of the tidal flats of western andros these vary between 0 5 to 0 04 mm yr the modern topography of the tidal flats was established by 2000 years bp similarly the modern geological features controlled by a tropical climate strictly dependent on hurricanes were already established by 2000 years bp and seem to have been initiated between 2500 and 2000 years bp

a comparison of observed and theoretical postglacial relative sea level in atlantic canada two extreme models of late wisconsinan ice cover in atlantic canada and the northeastern u s a are shown to produce postglacial relative sea level curves that bracket existing field observations at six sites throughout the region this suggests that the true late wisconsinan ice distribution is probably intermediate to the two contrasting reconstructions proposed both ice models predict the existence of four relative sea level zones an innermost zone closest to the centre of glaciation in which relative sea level falls continuously throughout postglacial time an outermost zone in which it rises continuously and two transitional zones in which it first falls and then rises in varying proportions according to the distance from the ice margin the distinctive forms of the relative sea level curves are probably representative of each of the zones and are unlikely to be significantly perturbed even by large local ice readvances they therefore establish patterns with which future field data are expected to conform the form that the geological record of relative sea level change is likely to take within each zone is discussed and promising settings for the collection of new data are proposed the common practice of separating relative sea level into an isostatic and a eustatic component is analysed and shown to be incorrect as usually applied the practice is also shown to be unnecessary because the models discussed in this paper predict changes in relative sea level that can be compared directly with the observations

a study of joints and stress release buckles in palaeozoic rocks of the niagara peninsula southern ontario joint sets in palaeozoic bedrock of the niagara peninsula occur at 005 045 085 and 135 orientations there is no consistent change in joint orientation with lithology rock age or location within the area drainage pattern analysis using airphotos and topographic maps indicates that glacial drift effectively masks underlying joint systems rare calcite and gypsum mineralization occurs along joints of 085 and 135 trend stress relief buckles indicate a contemporary maximum principal stress along an 050 trend joint systems in the niagara peninsula are similar in trend to those on the appalachian plateau

smooth or oscillating late holocene sea level curve evidence from cross regional statistical regressions of fixed biological indicators abstract what if any is the pattern of change of the late holocene sea level curve if a common pattern exists can it be better discerned in the non glaciated tectonically stable regions of the southern hemisphere and is sea level data more reliable from one type of marine sample than another to begin an investigation of these questions we present a review of regressing time elevation plots from the low to mid latitudes of the southern hemisphere based upon the differential between modern and past levels of various fixed biological indicators mainly calcareous tubeworms and corals stranded up to 2 m above present relative sea levels the sample sets come from our work in southeast australia and comparable work from north east australia the pacific islands and brazil we show that using evidence obtained from fixed intertidal tubeworm species there is no statistical exclusivity between the smooth and oscillating polynomials but corals are more problematic in situ tubeworm species with their reduced error bars in comparison to corals fulfil the condition of providing more robust results for statistical analysis regression curves based on these species point to cross regional similarities in the pattern of sea level movement of the last 6000 years across the lower latitudes of the southern hemisphere these statistical exercises while not able to yield definitive conclusions can highlight statistically equally likely alternative patterns of sea level movement which can then be tested by field evidence they can also give useful indications of the quality of sea level data obtained from different biological sources as in the difficulties in the use of corals compared to common intertidal tubeworm species

postglacial faulting in eastern canada nature origin and seismic hazard implications abstract at more than 70 locations in southeastern canada and the adjacent united states tiny bedrock faults displace glacial striations that are about 10 000 years old these reverse faults mostly of small displacement occur in a broad arc from western ontario to newfoundland the faults lie near the margin of the laurentian ice sheet strike generally tangential to it and imply compression nearly normal to the ene directed contemporary regional stress these observations and some age relationships suggest that the faults formed very soon after deglaciation perhaps in the first few thousand years after ice melting in each place and probably represent the release of stresses caused by flexural deformation of the upper crust although the individual offsets are small the faults are believed to be pervasive and individual outcrops reflect amounts of stress relief consistent with stresses implied by the postglacial tilt of nearby lake shorelines

postglacial emergence of western franz josef land russian and retreat of the barents sea ice sheet uncertainty remains on the timing and extent of late weichselian glaciers over the qsr barents and kara sea shelves franz josef land russia is a critical area for deciphering the record of glacier fluctuations and postglacial relative sea level change coastal forelands on the archipelago are covered by a well preserved raised beach sequence containing abundant and pristine driftwood whalebone and shell 4c dating of these materials provides site specific emergence records for the archipelago and some of the oldest ages on deglaciation of 10 400 bp three apparent still stands in emergence are inferred from morphology of the raised beach sequence and 4c dating between 9900 and 6200 bp and at ca 5500 bp and 3500 bp the earliest sea level arrest after formation of the marine limit reflects a balance between glacio isostasy and eustasy concomitant with the final phase of global sea level rise the latter two sea level arrests during the middle to late holocene are less pronounced and may indicate increased height of the ocean surface with greater storminess and extended open water conditions raised beaches at 1 2 m a s l and j4c dated at 1000 to 2000 bp give contemporary emergence rates of 1 to 2 mm year the low current rates of emergence on franz josef land are similar to areas in fennoscandinavia that sustained modest late weichselian glacier loads 1500 m within a few 100s of km of the inferred ice sheet margin the pattern of postglacial emergence and strandline tilts indicates that past glacier loads were greater over the adjacent barents sea than franz josef land marine and terrestrial records from franz josef land place retreat of glaciers from coastal areas by 10 400 bp whereas the adjacent franz victoria trough was deglaciated by 13 000 bp retreat of the barents sea ice sheet was probably underway by 13 500 bp coincident with rising global sea level and elevated summer insolation we infer that iceberg calving through the deep troughs bordering the barents sea particularly with rapidly rising sea level ca 12 000 bp was an important process controlling the demise of the barents sea ice sheet copyright 1996 elsevier science ltd

a history of neotectonic studies in ontario abstract first observations of geologically young rock faults and folds in new york in the late nineteenth century were shortly followed by others in ontario remapping of the paleozoic rocks began in the 1930s and quaternary geology mapping became organized in the 1950s leading to further discoveries of faults and folds in the bedrock engineering works in the niagara and hamilton areas from the 1890s to the 1970s encountered repeated problems of rock squeeze the separate geological and engineering experiences were linked in the 1970s and with heightened awareness discoveries of rock disturbances mainly popups greatly increased in the 1970s and 1980s understanding centered on high horizontal stress in the bedrock which became quantified through rock testing and modeling the creation of the multi agency group for neotectonics in eastern canada magnec in 1986 brought together a diverse group interested in all aspects of neotectonics including the distribution and causes of rock stress and the potential implications for seismic risk the existence of nuclear power plants sensitive to variations in the stress environment and high population densities near the great lakes provided motivation for further attention and prince edward county was designated for special study recent suggestions of reduced seismic activity under ice sheets and increased activity associated with isostatic uplift during their retreat lead to the question whether seismic risk is slowly decreasing as uplift rates decline

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

a high relative sea level stand in the middle holocene of southeastern tunisia abstract study of the marine holocene deposits in southeastern tunisia shows bioclastic beaches at elevations ranging between 0 and 100 cm above high tide level a h t l depending on the elevation of these fossilized shorelines the ages obtained are different the age of the older deposits ranges between 5900 and 4000 14cc yr b p 6400 4300 calendar yr b p there deposits consist of bioclastic beaches attaining an elevation of about 40 to 100 cm a h t l the younger deposit is dated at around 2100 14c years ago 1850 calendar yr b p and is found today at the same elevation as the present sea level this deposit also consists of bioclastic beach material and contains pottery fragments postglacial melting should not be responsible for this observed higher relative sea level stand because deglaciation ended about 7000 6000 14c years ago fairbanks 1989 furthermore the regularity of the paleobeach deposit elevation over a broad area in southeastern tunisia suggests that tectonics cannot explain the emergence the emergence of up to 1 m of marine deposits dating back to between 5900 and 4000 14c yr b p should rather be interpreted as the result in the region of a postglacial hydro isostatic rebound as predicted in the theological models of continental margins by for example clark et al 1978 and lambeck 1993 the present situation was reached 2100 14c years ago

oxygen isotopes and sea level from the time that detailed oxygen isotope records derived from foraminifera living in the constant temperature environment of the abyssal ocean became available there has been a discrepancy between the ice volume record that these records imply and that derived from the altitude of dated coral terraces around the world here we re examine the data and conclude that the temperature of the abyssal ocean has been an actively varying component of the climate system

holocene lake development and glacial isostatic uplift at lake skallen and lake oyako lutzow holm bay east antarctica based on biogeochemical facies and molecular signatures abstract the paleolimnology of two lakes which were isolated as a result of the crustal uplift during the late holocene along the soya coast lutzow holm bay east antarctica were studied the focus was on temporal variations in the biogeochemical composition of sediment cores recovered from lake skallen at skallen and lake oyako at skarvsnes both sets of lake sediments record environmental changes associated with a transition from marine to lacustrine settings as indicated by analyses of c and n contents nitrogen isotopic compositions 15 n and major element concentrations changes in the dominant primary producers during the marine lacustrine transition marine diatom to cyanobacteria at l skallen was clearly revealed by biogenic opal a diatom assemblages and molecular signature from denaturing gradient gel electrophoresis dgge with 16s ribosomal rna rrna gene analysis radiocarbon dating of acid insoluble organic c suggested that the environmental transition from marine to fresh water occurred at 2940 100 cal yr bp at l skallen and 1060 90 cal yr bp at l oyako based on these data a mean crustal uplift rate of 3 2 mm yr 1 is inferred for the history of marine lacustrine transition via brackish conditions the geological setting causing glacio isostatic uplift was the primary factor in controlling the transition event in sedimentary and biological facies

glacial isostatic adjustment i the forward problem summary the isostatic adjustment of a radially stratified visco elastic spheroid is treated using space time green functions for the associated surface mass load boundary value problem these impulse response functions are convolved with a heaviside function to give the time dependent deformation of the planet which would be produced by a unit point mass brought up from infinity at t 0 and allowed to remain on the surface the resulting heaviside green functions can be employed to simulate all of the important signatures of glacial isostatic adjustment given a space time dependent surface mass load consisting of ice sheet ablation histories and a model of the simultaneous filling of the ocean basins these source terms are simply convolved with the heaviside green function appropriate to a specific response signature a realistic model of the spatial distribution of the main late pleistocene ice loads and of their temporal disintegration is constructed the response of two visco elastic earth models is computed and compared to a global set of relaxation data relative sea level curves on the basis of this initial comparison of theory and observation the possibility that the lower mantle has a viscosity which is significantly in excess of the viscosity of the upper mantle is excluded in addition clear evidence of the presence of the lithosphere has been found in relaxation data from sites which were near the edge of the laurentide ice sheet such data should therefore prove useful as a basis for analysis of lateral variations in lithosphere thickness further extensions of the calculation are suggested

measurement requirements for glacial uplift detection of nonadiabatic density gradients in the mantle recent isotope studies have rekindled interest in the possibility that the mantle may be chemically stratified and therefore nonadiabatic previous calculations of the last ice age are compatible only with a 1022p mantle calculations of the isostatic response of an adiabatic partially nonadiabatic and fully nonadiabatic 1022p mantle to the load cycle of the last ice age show that the uplift responses of an adiabatic and even partially nonadiabatic mantle are very different however geoid perturbations mask these differences and the emergence curves of the two mantle types are nearly identical except in the regions near and under the ice loads at the early stages of isostatic readjustment the calculations suggest that we must seek shoreline emergence data around glaciated areas more than 6000 years before present if nonadiabatic density gradients in the mantle are to be detected from emergence data

postglacial sealevels in the pacific implications with respect to deglaciation regime and local tectonics nakiboglu sm lambeck k and aharon p 1983 postglacial sealevels in the pacific implications with respect to deglaciation regime and local tectonics tectonophysics 91 335 358 observations of holocene sealevel fluctuations contain forrnati on the mehing history of the major past ice sheets on the viscosity of the mantle and on vertical motions of tectonic origin seafevel changes at eleven sites in the southwest pacific region have been examined with the following results 1 the ice i model of peltier and andrews 1976 for arctic deglaciation is inadequate to explain all sealevels two alternative modifications of this model are a a forward shift in the deglaciation history with the onset of major melting starting at about 14 000 yrs ago and ending at 6ckto yrs ago fb the ice 1 model for the arctic deglaciation from 17 000 to 7000 yrs b p plus a significant amount of antarctic melt water 2 the effective mantle viscosity is in the range 10 lo22 p although the sealevel results for the locations studied are not strongly dependent on viscosity 3 vertical motions of tectonic origin can be separated from the hydro isostatic sealevel fhtctuations if these motions exceed about 0 5 mm yr i only two locations provide clear evidence for vertical motion consistent with independent geological observations the huon peninsula of new guinea is undergoing uplift of between 1 2 and 1 7 mm yr t while the hawaiian island of oahu is subsiding at a rate of about l 2 mm stations along the southeastern and eastern coast of australia are suggestive of small uplift of perhaps 0 5 i 0 mm yr i the sealevels in new zealand and the mnlacca straits are also found to be in agreement with other observations that point to regional tectonic stability

the effect of spatially non uniform water loads on prediction of sea level change summary numerical modelling of postglacial rebound predics a spatially variable pattern of sea level change yet many previous models predicting late pleistocene sea level change either neglect the load of water added to the oceans or assume a spatially uniform time dependent load over the whole ocean this is a poor approximation of the load near the former ice sheet since sea level change varies geographically in addition the coastline goemetry changes through time a spectral technique has been used to solve the sea level equation on an earth model with axisymmetric distribution of ice and oceans and also for a realistic ice ocean configuration the axisymmetric model is useful for demonstrating the fundamental physics involved in sea level changes caused by changes in surface loads in particular it can be seen that the elastic and gravitational response to the load is spread over a great distance whereas the viscous response is more localized a realistic ice ocean configuration has been used to demonstrate that neglect of the melt water load underestimates the amount of uplift in fennoscandia and other regions where rebound occurs in the ocean as previously noted by wu peltier 1983 in hudson bay and that movement of the coastlines and spatially varying water loads must both be included in calculations for the north sea and other near field regions with shallow seas sea level calculations including these effects and careful analysis of the sea level and ice melting record are required to determine modifications to the viscosity profile and ice model inferred by previous inaccurate models of the ocean load in the near field

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

sea level in time and space revolutions and inconvenient truths in this paper we identify four revolutions that in our view have shaped the study of sea level changes in recent decades i the search for eustasy one of the most hotly debated issues in the 1960s is still relevant as models of glacial isostatic adjustment gia require input of the amount of meltwater transferred to the world s oceans following the demise of the large pleistocene ice sheets ii resolution of sea level archives all sea level archives have limitations in their resolving power but are we willing to define these from studies of salt marsh deposits and corals it is highly likely that climate driven metre scale sea level fluctuations have not occurred during the middle and late holocene iii rapid sea level changes improved coring technology has resulted in the suggestion of meltwater pulses during the last deglaciation low frequency high magnitude events have been documented along seismically active shorelines and provide information on seismic hazards and storm impacts iv merging of empirical sea level investigations and models much sea level research in the past two decades has embraced the integration of models and field derived data providing testable hypotheses and insights into processes we conclude with some reminders about the inconvenient truths that keep the sea level scientist honest

a high precision record of mid late holocene sea level events from emergent coral pavements in the houtman abrolhos islands southwest australia early work on sea levels in southwest australia claimed to recognise a holocene sea level highstand which was not seen in better known sea level records elsewhere at the time more recent work has confirmed that a mid holocene highstand occurred about 6 kyr ago as new data on oscillating sea levels from the region have recently been published a high continuity precisely dated and accurately surveyed record was obtained from emergent coral pavements in the leeward houtman abrolhos islands serventy island a tectonically stable region from where good quality holocene sea level data have been previously obtained from corals from the mid holocene highstand ca 7 u th kyr ago sea level declined linearly during the remainder of the holocene as the carbonate platform prograded leewards hydro isostatic controls are probably significant in the record c 2005 elsevier ltd and inqua all rights reserved

coral reefs and sea level change abstract coral reefs provide significant evidence for former sea level positions because of their geological preservation and suitability for dating interpretation of this evidence presumes an understanding of reef geomorphology modern reef organism distributions and environmental factors influencing them fossil reef terraces formed during the last interglacial marine oxygen isotope mis substage 5e 128 116 ka are prevalent on many tropical shorelines and there has been ongoing debate as to the height reached by sea level during that highstand observations from numerous last interglacial sites suggest that sea level was at least 3 m above present sea level implying less extensive icesheets than at present an elevation of 6 m has commonly been adopted when correcting tectonically active sites for uplift recent compilations suggest elevations up to 8 9 m but incorporate few observations from reefs where the last interglacial is found below sea level oscillation of sea level during mis 5e has been interpreted from several sites with recent studies inferring rapid rise of several metres at the end of the interglacial these interpretations are at the limits to the precision with which corals can currently be dated and their palaeo water depths inferred it is not surprising that constraining last interglacial sea level changes within uncertainties of less than 1 2 m remains controversial considering sea level variations recognised between reef sites in the holocene and observed geographical variation in isostatic or flexural adjustments fossil coral reefs on uplifting margins also provide clear evidence for mis substages 5c and 5a and those on huon peninsula indicate fluctuations related to heinrich events mis 3 interpretations show considerable variability between sites with still greater uncertainties about sea level timing and elevation during previous interglacials future study of extensive sequences of fossil reefs preserved on rapidly subsiding margins could address these uncertainties submerged reefs have already yielded important information about sea level rise during the last deglaciation coring around barbados and tahiti as well as on the huon peninsula has produced a broadly consistent picture of ice melt reflecting eustatic change since the last glacial maximum these studies have shown the sensitivity of reefs to rapid sea level rise associated with meltwater pulses with some reefs drowning while others back stepped integrated ocean drilling program iodp expeditions to tahiti and recently the great barrier reef extended these records but details of timing nature and impact of deglacial meltwater pulses remain elusive studies of holocene reefs have indicated different growth strategies some kept up with sea level while others caught up when sea level decelerated holocene sea level appears to have experienced a gradual rise up to present across the caribbean providing accommodation space for reefs to accrete vertically whereas in the indo pacific sea level has been near its present level since 7 ka with many reef flats emergent following a slight fall of sea level caused by ocean siphoning microatolls on reef flats provide perhaps the clearest evidence of past sea level position but in their absence novel biological or other sea level indicators are required to better constrain palaeo water depths there is an urgent need for further research from additional key reef locations not only to decipher processes driving past sea level change and its geographical variability but also to better understand how coral reefs will respond in the context of future sea level rise

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

barrier island aggradation via inlet migration mustang island texas abstract after establishing its present location around 9 5 ka mustang island aggraded stacking over 20 m of barrier island sand in the same location throughout mustang island s history tidal inlets shifted within nearly the same location from 7 5 ka to the present leaving 10 15 m thick deposits of clean well sorted quartz sand deposited within only a few centuries these deposits lack some of the sedimentary features normally associated with tidal inlets such as tidal couplets and shell hash the lack of such features is attributed to the uniform nature of the deposits cut by the inlets during the island s relatively long period of aggradation mustang island was able to maintain an aggradation character throughout most of the holocene due to the sediment eroded from three sources pleistocene headlands the transgressive colorado river delta of texas and the ois 3 shoreline of the central texas shelf each of these sources was exposed to waves and accompanying longshore drift during the island s early history when sea level rose quickly but was flooded or capped by transgressive muds by the time sea level rise slowed during the middle holocene