revisiting tectonic corrections applied to pleistocene sea level highstands tectonic displacement contaminates estimates of peak eustatic sea level and equivalently minimum continental ice volumes determined from the elevation of quaternary interglacial highstand markers for sites at which a stratigraphic or geomorphic marker of peak marine isotope stage mis 5e sea level exists the standard approach for estimating local tectonic uplift or subsidence rates takes the difference between the elevation of the local highstand marker and a reference mis 5e eustatic value commonly chosen as 6 m and divides by the age of the marker the resulting rate is then applied to correct the elevation of all other local observed sea level markers for tectonic displacement including peak highstands of different ages e g mis 5a mis 5c and mis 11 under the assumption that the tectonic rate remained constant over those periods this approach introduces two potentially significant errors first the peak eustatic value adopted for mis 5e in most previous studies i e 6 m is likely incorrect second local peak sea level during mis 5e is characterized by significant departures from eustasy due to glacial isostatic adjustment in response to both successive glacial interglacial cycles and excess polar ice sheet melt relative to present day values we use numerical models of glacial isostatic adjustment that incorporate both of these effects to quantify the plausible range of the combined error and show that even at sites far from melting ice sheets local peak sea level during mis 5e may depart from eustasy by 2 4 m or more we also demonstrate that the associated error in the estimated tectonic rates can significantly alter previous estimates of peak eustatic sea level during quaternary highstands notably those associated with earlier interglacials e g mis 11

the role of ocean thermal expansion in last interglacial sea level rise 1 a compilation of paleoceanographic data and a coupled atmosphere ocean climate model were used to examine global ocean surface temperatures of the last interglacial lig period and to produce the first quantitative estimate of the role that ocean thermal expansion likely played in driving sea level rise above present day during the lig our analysis of the paleoclimatic data suggests a peak lig global sea surface temperature sst warming of 0 7 0 6 c compared to the late holocene our lig climate model simulation suggests a slight cooling of global average sst relative to preindustrial conditions sst 0 4 c with a reduction in atmospheric water vapor in the southern hemisphere driven by a northward shift of the intertropical convergence zone and substantially reduced seasonality in the southern hemisphere taken together the model and paleoceanographic data imply a minimal contribution of ocean thermal expansion to lig sea level rise above present day uncertainty remains but it seems unlikely that thermosteric sea level rise exceeded 0 4 0 3 m during the lig this constraint along with estimates of the sea level contributions from the greenland ice sheet glaciers and ice caps implies that 4 1 to 5 8 m of sea level rise during the last interglacial period was derived from the antarctic ice sheet these results reemphasize the concern that both the antarctic and greenland ice sheets may be more sensitive to temperature than widely thought

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

piezometer friction cone investigation at a tailings dam static piezometer friction cone tests were carried out at the tailings dam at brenda mines peachland british columbia to evaluate soil characteristics and seepage conditions in the dam several t

the sea level fingerprints of ice sheet collapse during interglacial periods abstract studies of sea level during previous interglacials provide insight into the stability of polar ice sheets in the face of global climate change commonly these studies correct ancient sea level highstands for the contaminating effect of isostatic adjustment associated with past ice age cycles and interpret the residuals as being equivalent to the peak eustatic sea level associated with excess melting relative to present day of ancient polar ice sheets however the collapse of polar ice sheets produces a distinct geometry or fingerprint of sea level change which must be accounted for to accurately infer peak eustatic sea level from site specific residual highstands to explore this issue we compute fingerprints associated with the collapse of the greenland ice sheet west antarctic ice sheet and marine sectors of the east antarctic ice sheet in order to isolate regions that would have been subject to greater than eustatic sea level change for all three cases these fingerprints are more robust than those associated with modern melting events when applied to infer eustatic sea level because 1 a significant collapse of polar ice sheets reduces the sensitivity of the computed fingerprints to uncertainties in the geometry of the melt regions and 2 the sea level signal associated with the collapse will dominate the signal from steric effects we evaluate these fingerprints at a suite of sites where sea level records from interglacial marine isotopes stages mis 5e and 11 have been obtained using these results we demonstrate that previously discrepant estimates of peak eustatic sea level during mis5e based on sea level markers in australia and the seychelles are brought into closer accord

first demonstration of surface currents imaged by hybrid along and cross track interferometric sar this paper is concerned with the simultaneous measurement of terrain heights and currents using an airborne interferometric synthetic aperture radar insar for the first time a hybrid two antenna insar system with both along and across track baseline components is used to measure high resolution digital elevation maps dems and current fields in a wadden sea area coastal applications like the monitoring of sediment transport or the numerical modeling of morphodynamic processes require measurements of topography and currents classical in situ measurements of these parameters are both expensive and time consuming or even impossible if higher spatial resolution is required pure along track interferometers atis have demonstrated their ability to provide information on ocean currents while across track interferometric systems xtis have been successfully used to measure dems in this paper a hybrid system with both ati and xti components is used to acquire synoptic measurement for the first time an experiment with an airborne system taking data over a wadden sea area is presented demonstrating the potential of the technique a geometrical model is developed for the interferometric phase of hybrid insar systems this model combines ati and xti techniques using a baseline that spans between two antennas consisting of along track and across track components in this model both the effect of topography and the radial velocity of the water surface enter into the resulting interferometric phase to separate both components the system takes data of the respective scene flying two or more tracks with different flight directions e g antiparallel tracks this approach leads to a set of linear equations that has a unique solution for the along and cross track phase finally an additional phase bias has to be considered due to the radial velocity and the influence of squint this is caused by a misregistration effect between both antennas which is related to cross track imaging of surface motion the new insar technique is tested with data acquired during a campaign in february 1997 over the weser estuary at the german coast the airborne insar system aes 1 was used the interferometer configuration consists of two sar antennas separated by a mixed along track and cross track baseline two datasets acquired on antiparallel tracks are used the calculated velocities were compared with a hydrodynamic model operated by the federal waterway engineering and research establishment the experimental results agree well with the numerical model in particular the mean velocity of 0 7 ms sup 1 matches in both datasets deviations in the fine scale structure of the current field are discussed topographic analysis and validation are performed in a separate investigation the impact of surface gravity waves and wind drift which are known to cause significant artifacts in the ati phase under certain circumstances is discussed

a brief introduction to cone penetration testing cpt in frozen geomaterials the cone penetration test has been successfully used to classify soil for 100 years however it has received only limited contemporary use in frozen geomaterials the historical and contemporary use of the cone penetration test in various frozen geomaterials is considered here and contemporary data from recent work in polar snow are examined it is probable that many material physical properties e g density strength and microstructure can be obtained directly from cone penetration testing it appears under utilized as a contemporary scientific and engineering investigative tool in frozen geomaterials

cone penetration testing cpt in antarctic firn an introduction to interpretation commercial cone penetration testing cpt equipment was adapted to allow penetrative testing in hard polar firn to depths of 10 m the apparatus is hydraulically driven rate controllable and able to penetrate firn with a resistance of 10 mpa it can be mounted on many types of typical polar vehicles requiring connection to only hydraulics and 12 v electricity data recorded include both cone tip resistance and sleeve friction a parameter not previously examined through such testing this paper describes the development and calibration of the equipment and examines factors including snow density penetration rate and cone size and shape that are shown to affect cpt interpretation cpt can be used efficiently in polar environments to potentially provide estimates of physical parameters in hard firn to substantial depth

gps estimates of microplate motions northern caribbean evidence for a hispaniola microplate and implications for earthquake hazard summary we use elastic block modelling of 126 gps site velocities from jamaica hispaniola puerto rico and other islands in the northern caribbean to test for the existence of a hispaniola microplate and estimate angular velocities for the gonave hispaniola puerto rico virgin islands and two smaller microplates relative to each other and the caribbean and north america plates a model in which the gonave microplate spans the whole plate boundary between the cayman spreading centre and mona passage west of puerto rico is rejected at a high confidence level the data instead require an independently moving hispaniola microplate between the mona passage and a likely diffuse boundary within or offshore from western hispaniola our updated angular velocities predict 6 8 1 0 mm yr 1 of left lateral slip along the seismically hazardous enriquillo plantain garden fault zone of southwest hispaniola 9 8 2 0 mm yr 1 of slip along the septentrional fault of northern hispaniola and 14 15 mm yr 1 of left lateral slip along the oriente fault south of cuba they also predict 5 7 1 mm yr 1 of fault normal motion in the vicinity of the enriquillo plantain garden fault zone faster than previously estimated and possibly accommodated by folds and faults in the enriquillo plantain garden fault zone borderlands our new and a previous estimate of gonave caribbean plate motion suggest that enough elastic strain accumulates to generate one to two mw 7 earthquakes per century along the enriquillo plantain garden and nearby faults of southwest hispaniola that the 2010 m 7 0 haiti earthquake ended a 240 yr long period of seismic quiescence in this region raises concerns that it could mark the onset of a new earthquake sequence that will relieve elastic strain that has accumulated since the late 18th century

collapse of polar ice sheets during the stage 11 interglacial the magnitude of sea level rise during marine isotope stage 11 about 400 000 years ago is shown to have been probably only 6 to 13 metres in contrast to some earlier estimates of up to 20 metres the ice sheets in greenland and west antarctica are known to be susceptible to climate warming and both are losing mass how the east antarctic ice sheet will respond to warming is less clear recent evidence from shoreline features in bermuda and the bahamas suggested that during marine isotope stage 11 a period of warming that occurred about 400 000 years ago the sea level was 20 metres higher than it is today which pointed to significant melting of the east antarctic ice sheet now an estimate that takes into account post glacial crustal subsidence of the shoreline sites during an anomalously long interglacial period puts the sea level during stage 11 at 6 13 metres higher than today that can be explained by the collapse of the greenland and west antarctic ice sheets with only a small contribution from the east antarctic ice sheet contentious observations of pleistocene shoreline features on the tectonically stable islands of bermuda and the bahamas have suggested that sea level about 400 000 years ago was more than 20 metres higher than it is today1 2 3 4 geochronologic and geomorphic evidence indicates that these features formed during interglacial marine isotope stage mis 11 an unusually long interval of warmth during the ice age1 2 3 4 previous work has advanced two divergent hypotheses for these shoreline features first significant melting of the east antarctic ice sheet in addition to the collapse of the west antarctic ice sheet and the greenland ice sheet1 2 3 or second emplacement by a mega tsunami during mis 11 ref 4 5 here we show that the elevations of these features are corrected downwards by 10 metres when we account for post glacial crustal subsidence of these sites over the course of the anomalously long interglacial on the basis of this correction we estimate that eustatic sea level rose to 6 13 m above the present day value in the second half of mis 11 this suggests that both the greenland ice sheet and the west antarctic ice sheet collapsed during the protracted warm period while changes in the volume of the east antarctic ice sheet were relatively minor thereby resolving the long standing controversy over the stability of the east antarctic ice sheet during mis 11

relative sea level fall since the last interglacial stage are coasts uplifting worldwide the growing interest in quantification of vertical ground motion stems from the need to understand in detail how the earth s crust behaves for both scientific and social reasons however only recently has the refinement of dating techniques made possible the use of paleoshorelines as reliable tools for tectonic studies although there are many local studies of quaternary vertical motions of coastlines we know of no comprehensive worldwide synthesis here we provide a compilation of 890 records of paleoshoreline sequences with particular emphasis on the last interglacial stage marine isotopic stage mis 5e 122 ka the quality of dating mis 5e makes it a reliable marker to evaluate vertical ground motion rates during the late quaternary on a global scale the results show that most coastal segments have risen relative to sea level with a mean uplift rate higher than 0 2 mm yr i e more than four times faster than the estimated eustatic drop in sea level the results also reveal that the uplift rate is faster on average for active margins than for passive margins neither dynamic topography nor glacio hydro isostasy may explain sustained uplift of all continental margins as revealed by the wide distribution of uplifted sequences of paleoshorelines instead we suggest that only plate tectonic processes reconcile all observations of quaternary coastal uplift we propose that long term continental accretion has led to compression of continental plates and uplift of their margins therefore this study concludes that plate tectonics processes impact all margins and emphasizes the fact that the notion of a stable platform is unrealistic these results therefore seriously challenge the evaluation of past sea levels from the fossil shoreline record

ice sheet collapse following a prolonged period of stable sea level during the last interglacial sea level during the last interglacial period reached a peak of between 5 and 9 m above the present day level a detailed reconstruction of sea level and isostatic rebound from western australia indicates a prolonged period of sea level stability at 3 4 m above present followed by an abrupt sea level rise of 5 6 m

energy density directional spectra of a nearshore wave field measured by interferometric synthetic aperture radar the nearshore wave field within monterey bay california is studied using remote sensing imaging by an interferometric synthetic aperture radar insar and simultaneous ground based measurements it is shown that insar imagery of the ocean surface offers some advantages over conventional synthetic aperture radar because of the direct imaging mechanism of insar quantitative information about the complicated wave field can be obtained the insar derived directional energy density spectra and the corresponding ground based spectra compare well

reconciliation of sea level observations in the western north atlantic during the last glacial cycle abstract a south to north gradient of increasing marine isotope substage mis 5a 80 ka bp sea level has been recorded across the caribbean and surrounding region relative to present mis 5a sea levels range from 19 m to more than 3 m between barbados haiti the bahamas florida bermuda and the us atlantic coast in contrast no gradient in sea level is observed for the last interglacial period mis 5e 128 118 ka bp at tectonically stable localities in the same region with deposits generally lying several metres above present we demonstrate here that these controversial observations are reconciled by taking into account the isostatic response of the earth to glacial loading and unloading a fundamental effect that is commonly overlooked in the interpretation of sea level observations from different locations to define a global sea level curve furthermore the observed gradient can be used to place constraints on earth rheology and is an important indicator of the behaviour of the north american ice sheets during the last glacial cycle

actively evolving microplate formation by oblique collision and sideways motion along strike slip faults an example from the northeastern caribbean plate margin abstract the pattern of folding faulting and late quaternary coral reef uplift rates in western and central hispaniola haiti and dominican republic suggest that the elongate gonave microplate a 190 000 km2 area of the northeastern caribbean plate is in the process of shearing off the caribbean plate and accreting to the north american plate late cenozoic transpression between the southeastern bahama platform and the caribbean plate in hispaniola has inhibited the eastward motion of the northeastern corner of the plate transpression is manifested in western and central hispaniola by the formation of regional scale folds that correspond to present day anticlinal topographic mountain chains continuous with offshore anticlinal ridges areas of most rapid quaternary uplift determined from onland coral reefs 125 ka and younger coincide with the axial traces of these folds offshore data suggest recent folding and faulting of the seafloor onshore reef data do not conclusively require late quaternary folding but demonstrate that tectonic uplift rates of the axial areas of the anticlines decrease from the northwest peninsula of haiti 0 37 mm yr to to the central part of the coast of western haiti 0 19 mm yr to the south central part of western haiti 0 mm yr formation of the 1200 km long enriquillo plantain garden walton fault zone as a bypass strike slip fault has isolated the southern edge of the gonave microplate and is allowing continued unimpeded eastward motion of a smaller caribbean plate past the zone of late neogene convergence and quaternary uplift of coral reefs in hispaniola offshore seismic reflection data from the jamaica passage the marine strait separating jamaica and haiti show that the enriquillo plantain garden fault zone forms a narrow but deep active fault bounded trough beneath the passage the active fault is continuous with active faults mapped onshore in western haiti and eastern jamaica the bathymetric deep is present because the jamaica passage fault segment represents a 50 km wide transtensional left step of the fault trace between haiti and jamaica onshore satellite imagery and field observations suggest that the enriquillo plantain garden fault forms a continuous trace extending from central hispaniola east of lake enriquillo dominican republic to the westernmost end of the southern peninsula of haiti the regional lineament corresponds to a recent fault scarp in quaternary alluvium of the clonard pull apart basin in the central part of the southern peninsula of haiti and suggests that at least this part of the lineament has undergone recent slip calmus 1983 has suggested a total offset of 30 50 km of the enriquillo plantain garden fault zone in the southern peninsula of haiti using the apparent offset of lithologic units seismic reflection data from lake enriquillo document recent deformation of quaternary lake sediments where the lineament crosses the lake leveling of the crest of a late holocene coral reef and associated algal tufa around lake enriquillo demonstrate late holocene vertical movement and tilting in a 1500 m wide zone parallel to the fault trend lateral offset is difficult to show in the enriquillo valley area because of rapid recent sedimentation into the valley the pattern of inactive strike slip faults and fold belts of cenozoic age in cuba and the yucatan basin suggest that two elongate microplates were sheared off the proto caribbean plate and accreted to the north american plate by a similar process in paleocene and eocene times age of terminal deformation in western central and eastern cuba is consistent with southeastward younging and migration of arc collision the similarity of the size and sequence of events in cuba suggests that the process of oblique collision and sideways motion of the plate along a new strike slip fault towards a free face may be an important process of microplate formation and interplate transfer in other areas

laser ablation u series analysis of fossil bones and teeth abstract over the past decade we have applied laser ablation icp mass spectrometry u series analysis to a large number of bones and teeth the method is fast and provides high resolution data of u series isotopes which give insights into the complexity of uranium migration into within and out of bones in this paper we present our laser ablation approach in detail from the experimental set up to data reduction and uranium diffusion modelling laser ablation analysis can now be applied with minimum damage complete diffusion data sets can be obtained by laser drilling which leaves a hole of around 200 m in diameter and 1 2 mm depth if the natural u diffusion follows a simple single stage process valuable age information can be obtained in other cases highly complex u migrations have been observed which make any age assessment impossible two examples from wadjak and callao illustrate the potential of nearly non destructive laser ablation u series analysis of human skeletal tissues the results demonstrate the physical presence of modern humans in south east asia at a time when our species just started to migrate into europe

the paradox of drowned reefs and carbonate platforms shallow water carbonate platforms and reefs are drowned when tectonic subsidence or rising sea level outpaces carbonate accumulation and benthonic carbonate production ceases drowned platforms are common in the geologic record but they present a paradox if one considers rates of processes involved during the early holocene when sea level rose at rates of 6 000 to 10 000 m yr mm 1 000 yr most reefs and platforms were outpaced by the rising sea during the late holocene with sea level rising 500 to 3 000 m yr in the atlantic caribbean area reefs and platforms started to recover built to sea level and prograded seaward 1 000 m yr is thus a conservative estimate of the average growth potential of modern reefs and platforms independently accumulation rates of prograding platforms in the geologic record suggest growth potential in excess of several hundred microns per year the growth potential of 1 000 m yr exceeds any relative rise of sea level caused by long term processes in the geologic record newly formed ocean crust subsides at a maximum of 250 m yr basin subsidence averages 10 to 100 m yr and sea level rises due to increased sea floor spreading amount to less than 10 m yr rapid pulses of relative rise of sea level or reduction of benthic growth by deterioration of the environment remain the only plausible explanations of drowning the geologic record shows examples of both of these processes global mass extinctions of reefs and platforms occurred in the middle cretaceous eustatic rise due to submarine volcanism or desiccation of a small ocean basin and the late devonian global crisis of ocean environment extraterrestrial cause drowning controlled by regional tectonics prevailed in the jurassic and early cretaceous of the tethyan realm and the drowning of mesozoic platforms in the western north atlantic seems to have been dictated by plate tectonic drift to higher latitudes

rate controlled cone penetration tests in permafrost cone penetration tests cpts were carried out in the summers of 1999 and 2000 in a permafrost mound near umiujaq in northern quebec canada to study the cryostratigraphy and assess the creep behaviour of permafrost a new linear pushing system using an actuator technology was specifically designed and developed to accurately control the penetration rate of the cone in the permafrost this system has a load capacity of about 113 kn at a maximum penetration rate of 1 5875 cm s and a stroke of 120 cm and can provide constant penetration rates as low as 4 10 6 cm s it can be disassembled in pieces for easy hand transport and use in remote locations two different types of cpt were performed in the permafrost mound stratigraphic profiling and creep test the first type is a quasi static cpt at a penetration rate of 0 1 cm s providing a stratigraphic profile of permafrost in terms of the measurement of penetrometer sensors as a function of depth the second type is a series of quasi static cpts at incre

seismic hazard along the southern boundary of the gonave microplate block modelling of gps velocities from jamaica and nearby islands northern caribbean summary we use block modelling of gps site velocities from jamaica and nearby islands including hispaniola to test alternative plate boundary geometries for deformation in jamaica and estimate slip rates along the island s major fault zones relative to the caribbean plate gps sites in northern jamaica move 6 0 0 5 mm yr 1 to the wsw constituting a lower bound on the motion of the gonave microplate across its southern boundary in jamaica obliquely convergent motion of all 30 gps sites on and near jamaica relative to the island s e w trending strike slip faults may be partitioned into 2 6 0 6 mm yr 1 of n s shortening across submarine faults south of jamaica and 5 6 mm yr 1 of e w motion guided by geological and seismic information about the strikes and locations of faults in jamaica inverse block modelling of the regional gps velocities rejects plate boundary configurations that presume either a narrow plate boundary in jamaica or deformation concentrated across a restraining bend defined by the topographically high blue mountains of eastern jamaica the best fitting models instead place most deformation on faults in central jamaica the 4 5 mm yr 1 slip rate we estimate for the plantain garden fault and blue mountain restraining bend of southeastern jamaica implies significant seismic hazard for the nearby capital of kingston

holocene sea level change and coastal landscape evolution in the southern gulf of carpentaria australia a revised holocene sea level history for the southern gulf of carpentaria is presented based on new data from the south wellesley archipelago and age recalibration of previous research results confirm that rising sea levels during the most recent post glacial marine transgression breached the arafura sill ca 11 700 cal yr bp sea levels continued to rise to ca 30 m by 10 000 cal yr bp leading to full marine conditions by 7700 cal yr bp sea level reached present mean sea level pmsl and continued to rise to an elevation of between 1 5 m and 2 m above pmsl sea level remained ca 1 5 between 7000 and 4000 cal yr bp followed by rapid regression to within 0 5 m of pmsl by ca 3500 cal yr bp when placed into a wider regional context results from this study show that coastal landscape evolution in the tropical north of australia was not only dependent on sea level change but also show a direct correlation with holocene climate variability specifically the formation and preservation of beach rock deposits intertidal successions beach and chenier ridge systems hold valuable sea level and holocene climate proxies that can contribute to the growing research into lower latitude holocene sea level and climate histories

coastal uplift rate at matanzas cuba inferred from mis5e phreatic overgrowths on speleothems many morphological elements in cuba s landscape e g marine terraces tidal notches demonstrate that coastal uplift has taken place but the rate at which this occurs is not known carbonate phreatic overgrowths on speleothems have been found in a cave in central north cuba 1 km from the present coastline at 16 m asl they form exceptional and unique mushroom shaped speleothems and balconies decorating the walls of the rooms these phreatic overgrowths on speleothems pos formed at the oscillating air water interface in sea level controlled anchialine lakes u th dating of these overgrowths suggests ages that are compatible with the marine isotope stage 5e i e 130 115 ka these pos have fixed this sea level highstand and demonstrate that this part of cuba has been subjected to a much lower uplift rate than previously reported i e less than 0 1 mm a 1 since the last interglacial this article is protected by copyright all rights reserved

palaeohydrological significance of late quaternary strontium isotope ratios in a tropical lake ostracods preserved in late quaternary sediments of wallywash great pond a fresh coastal lake in sw jamaica record temporal variations in the strontium isotope composition of lake water oxygen isotope and sr ca ratios in ostracods reveal temporal variations in the lake s hydrology related to effective precipitation and in its salinity related to varying marine saline groundwater input from changes in relative sea level evaluation of isotopic and trace element data indicates that the stratigraphic variations in 87sr 86sr ratios during the late quaternary are best explained by climatically controlled hydrological changes during wetter periods the lake s sr budget was dominated by springwater input with relatively low 87sr 86sr ratio whereas during drier times reduced springflow possibly coupled with input of more radiogenic sr from other sources such as sea spray aerosols and perhaps saharan dust led to an increase in the sr isotope ratio of the lake water despite proximity of the lake to the sea and evidence for slight intrusion of marine saline groundwater in the past however the extent of marine input appears to have had limited influence on the lake s sr isotope ratios whereas the 87sr 86sr ratios cannot be used as a palaeosalinity proxy in this particular lake they do provide valuable information about the mechanisms underlying hydrological change

a probabilistic assessment of sea level variations within the last interglacial stage robert e kopp 1 frederik j simons 2 jerry x mitrovica 3 adam c maloof2 and michael oppenheimer2 4 1department of earth and planetary sciences and rutgers energy institute rutgers university piscataway nj 08854 usa e mail robert kopp rutgers edu 2department of geosciences princeton university princeton nj 08544 usa 3department of earth and planetary sciences harvard university cambridge ma 02138 usa 4woodrow wilson school of public and international affairs princeton university princeton nj 08544 usa

remote sensing of suspended sediment concentration flow velocity and lake recharge in the peace athabasca delta canada 1 the transport of fine sediment carried in suspension by water is central to the hydrology geomorphology and ecological functioning of river floodplains and deltas an extensive new field data set for the peace athabasca delta pad canada quantifies robust positive relationships between in situ suspended sediment concentration ssc and remotely sensed visible near infrared reflectance these relationships are exploited using spot and aster satellite images to map suspended sediment concentrations across the pad for four days in 2006 and 2007 revealing strong variations in water sources and flow patterns including flow reversals in major distributaries near daily monitoring with 276 modis satellite images tracks hydrologic recharge of floodplain lakes as revealed by episodic infusions of sediment rich water from the athabasca river the timing and magnitude of lake recharge are linked to springtime water level on the athabasca river suggesting a system sensitive to changes in river flow regime moreover recharge timing differentiates lakes that are frequently and extensively recharged from those recharged more rarely finally we present a first estimation of river flow velocity based on remotely sensed ssc though saturation may occur at velocities 0 6 m s viewed collectively the different remote sensing methodologies presented here suggest strong value for visible near infrared remote sensing of suspended sediment to assess hydrologic and sediment transport processes in complex flow environments field observations including nephelometric turbidity specific conductivity water temperature secchi disk depth suspended sediment concentration and water level are archived at the oak ridge national laboratory distributed active archive center for biogeochemical dynamics available at http daac ornl gov hydroclimatology guides pad html

the anatomy of interglacial sea levels the relationship between sea levels and ice volumes during the last interglacial abstract the elevations and chronology of interglacial shorelines and other sea level indicators provide information on ice volumes for these earlier periods compared with today but as for the holocene the relationship between sea levels and ice volumes for earlier interglacials is not simple because of the planet s deformational gravitational and rotational response to changes in ice water loads glacio hydro isostasy in particular the pattern of global sea level for a particular interglacial will be a function of the earth and ocean response to ice loads applied before during and after the interglacial in question this paper examines the role of glacio hydro isostasy during these glacial cycles to make three key points the first is to demonstrate why interglacial sea levels cannot be interpreted directly in terms of ice volume the second is to illustrate the spatial variability that can be expected in interglacial sea levels because of the earth s isostatic response to changing ice and water loads and to demonstrate why observations from different localities should not be combined into a single sea level function without first correcting for differential isostatic effects the third addresses the question whether in the absence of perfect knowledge of the ice sheets and earth rheology inferences can be made about ice volumes during an interglacial we conclude that if these isostatic factors are ignored interpretations of interglacial sea levels can lead to serious errors in the inferences about ice volumes during the interglacials

observations of steady longshore currents in the surf zone abstract steady surf zone longshore currents and directional properties of the incident wave field were measured on a beach with nearly straight and parallel depth contours selected data were processed into 64 segments each of 68 2 min duration irregularly spaced throughout an 18 day period a wide variety of incident wave and longshore current conditions were observed the radiation stress spectrum sxy f was estimated from a slope array and two current meters located seaward of the surf zone in many cases the total radiation stress sxyt sxy f f contains important contributions from a wide range of frequencies in a few instances sea and swell approach the beach from different directions quadrants resulting in a new zero sxyt the strong shears and direction reversals of the longshore current that could conceivably occur in this circumstance were not observed an eof decomposition of the mean longshore current pattern shows that most 90 of the current spatial variation in the 64 runs is

complex rupture during the 12 january 2010 haiti earthquake initially the devastating mw 7 0 12 january 2010 haiti earthquake seemed to involve straightforward accommodation of oblique relative motion between the caribbean and north american plates along the enriquillo plantain garden fault zone here we combine seismological observations geologic field data and space geodetic measurements to show that instead the rupture process involved slip on multiple faults primary surface deformation was driven by rupture on blind thrust faults with only minor deep lateral slip along or near the main enriquillo plantain garden fault zone thus the event only partially relieved centuries of accumulated left lateral strain on a small part of the plate boundary system together with the predominance of shallow off fault thrusting the lack of surface deformation implies that remaining shallow shear strain will be released in future surface rupturing earthquakes on the enriquillo plantain garden fault zone as occurred in inferred holocene and probable historic events we suggest that the geological signature of this earthquake broad warping and coastal deformation rather than surface rupture along the main fault zone will not be easily recognized by standard palaeoseismic studies we conclude that similarly complex earthquakes in tectonic environments that accommodate both translation and convergence such as the san andreas fault through the transverse ranges of california may be missing from the prehistoric earthquake record

on post glacial sea level i general theory summary modern analyses of sea level changes due to glacial isostatic adjustment gia are based on the classic sea level equation derived by farrell clark 1976 geophys j r astr soc 46 647 667 the connection between global sea level variations and changes to ocean height that is assumed within this equation breaks down in the presence of a time varying shoreline geometry we present a generalized sea level equation that overcomes this difficulty we also derive analytic expressions for and present schematic illustrations of the error in the ocean height change over finite time intervals introduced in published efforts to incorporate shoreline evolution into the theory of gia induced sea level change this comparison includes studies of shoreline migration due to either local sea level changes or the growth and ablation of marine based ice we conclude that the theories applied by johnston 1993 geophys j int 114 615 634 milne 1998 phd thesis university of toronto toronto and co workers are more accurate than the procedure advocated by peltier 1994 science 265 195 201 1998a geophys res lett 25 3955 3958 1998b rev geophys 114 615 634 although an improvement in the latter has recently been reported peltier drummond 2002 geophys res lett 29 10 1029 2001gl014273 our generalized theory is valid for any earth model in a companion paper we derive the equations necessary to treat the special case of a spherically symmetric linear viscoelastic and rotating earth and we quantify errors associated with previous work

measurements of sea surface currents in the baltic sea region using spaceborne along track insar the main challenging problems in ocean current retrieval from along track interferometric ati synthetic aperture radar sar are phase calibration and wave bias removal in this paper a method based on differential insar dinsar technique for correcting the phase offset and its variation is proposed the wave bias removal is assessed using two different doppler models and two different wind sources in addition to the wind provided by an atmospheric model the wind speed used for wave correction in this work is extracted from the calibrated sar backscatter this demonstrates that current retrieval from ati sar can be completed independently of atmospheric models the retrieved currents from four tandem x tdx acquisitions over the oresund channel in the baltic sea are compared to a regional ocean circulation model it is shown that by applying the proposed phase correction and wave bias removal a good agreement in spatial variation and current direction is achieved the residual bias between the ocean model and the current retrievals varies between 0 013 and 0 3 m s depending on the doppler model and wind source used for wave correction this paper shows that using sar as a source of wind speed reduces the bias and root mean squared error rmse of the retrieved currents by 20 and 15 respectively finally the sensitivity of the sea current retrieval to doppler model and wind errors are discussed

sea level rise due to polar ice sheet mass loss during past warm periods background although thermal expansion of seawater and melting of mountain glaciers have dominated global mean sea level gmsl rise over the last century mass loss from the greenland and antarctic ice sheets is expected to exceed other contributions to gmsl rise under future warming to better constrain polarice sheetresponse to warmer temperatures we draw on evidence from in terglacial periods in the geologic record that ex perienced warmer polar temperatures and higher gmsls than present coastal records of sea level from these previous warm periods dem onstrate geographic variability because of the influence of several geophysical processes that operate across a range of magnitudes and time scales inferring gmsl and ice volume changes from these reconstructions is nontrivial and generally requires the use of geophysical models advances interdisciplinary studies of geo logic archives have ushered in a new era of deciphering magnitudes rates and sources of sea level rise advances in our understanding of polar ice sheet response to warmer climates have been made through an increase in the number and geographic distribution of sea level reconstructions better ice sheet constraints and the recognition that several geophysical processes cause spatially complex patterns in sea level in particular accounting for glacial isostatic processes helps to decipher spatial variability in coastal sea level records and has reconciled a number of site specific sea level reconstructions for warm periods that have oc curred within the past several hundred thou sand years this enables us to infer that during recent interglacial periods small increases in

impacts of permafrost degradation on a road embankment at umiujaq in nunavik quebec canada differential subsidence of as much as 0 85 m is affecting the access road to umiujaq airport in nunavik quebec canada located in the discontinuous permafrost zone a geotechnical and geophysical investigation including piezocone test ground penetrating radar profiling electrical resistivity tomography and numerical modeling of the thermal regime of the road embankment and subgrade is presented to characterize the ground stratigraphy and permafrost conditions and to assess the exact causes and effects of permafrost degradation on the road embankment the subsidence is due to thaw consolidation taking place in a layer of ice rich silt underneath a superficial sand layer while the seasonal freeze thaw cycles were initially restricted to the sand layer the thawing front has now reached the thaw unstable ice rich silt layer according to our numerical modeling the increase in air temperature recently observed in nunavik cannot be the sole cause of the observed subsidence affecting this engineering st

generation of high precision dems of the wadden sea with airborne interferometric sar this paper describes how high precision digital elevation models dems are obtained over the wadden sea using the aes 1 airborne interferometric radar the wadden sea is an intertidal zone along the coast having height variations less than 5 m over 30 km and is free of vegetation the resulting dem has a grid spacing of 2 5 m and an absolute height accuracy of 5 cm root mean square rms as verified by theodolite measurements this paper describes the radar system the processing techniques the test area the results and the verification procedure

sea level oscillations during the last interglacial highstand recorded by bahamas corals whether sea level was stable during the last interglacial remains a subject of debate an analysis of the u th ages of coral reefs in the bahamas corrected for open system behaviour confirms the presence of at least one oscillation within the sea level highstand

evolution of marine terraces and sea level in the last interglacial cave hill barbados the uplifted marine terrace of last interglacial stage 5e age at cave hill barbados has been investigated with views toward terrace architecture developmental processes and sea level history methods include stratigraphic analysis of new deep exposures precise 230th geochronology and geomorphic mapping cave hill was central to earlier studies that led to important ideas on reef and terrace evolution but with which we find significant disagreement we present a new model of terrace evolution that emphasizes the role of marine erosion deposition of carbonate cover during the full eustatic cycle rather than only at highstand and principal reef development during transgression rather than at highstand by keep up rather than catch up growth the new model and geochronology contribute to an improved understanding of surficial processes during emergence of uplifting coral coasts and of global sea level changes in the last interglacial transgression in stage 5e at cave hill was accompanied by progressive marine erosion of a terrace floor and receding seacliff and deposition of a seaward thickening reefal wedge on the floor and above limestones of stage 6 and 7 ages the wedge contains a diachronous basal acropora palmata fringe reef this is overlain by an in place a cervicornis reef that aggraded progressively during sea level rise the transgressive phase took place between 136 ka or earlier and ca 128 ka during highstand between ca 127 and 120 ka the floor and seacliff continued to recede landward re gression began at or after ca 120 ka and sea level fell 37 m below the highstand level by ca 115 ka in stage 5c the seaward front of the last interglacial terrace was eroded landward an uncertain distance the sea level record at cave hill has implications for timing and constituent events of the penultimate glacial the last interglacial highstand and the fall in sea level at the transition from stage 5e to stage 5d shoreline angles which are isochronous linear geomorphic features are the most accurate markers of sustained highstand levels highstand levels and uplift rates interpreted from a palmata in barbados are less accurate and lower because the coral grew mainly in transgression the coral derived data therefore include uncertainties of depths of growth and collapse

ocean surface features and currents measured with synthetic aperture radar interferometry and hf radar this paper describes the results of the first quantitative comparison between high resolution ocean surface current fields extracted from interferometric synthetic aperture radar insar measurements and those from a high frequency hf ocean surface current radar oscr system data from each of these radar systems along with supporting measurements from shipboard and buoy mounted sensors were collected during the high resolution remote sensing experiment high res on june 20 1993 on the continental shelf off the coast of cape hatteras north carolina both components of the surface current were obtained from the insar system at roughly 10 m resolution from two orthogonal flight legs over the region separated in time by about 30 min the oscr system measured two dimensional surface current vectors at about 1 km resolution over this same region while the usns bartlett was collecting hydrographic samples and near surface current measurements two dimensional wave spectra as well as meteorological and additional current measurements were collected at two buoys within the experimental area we discuss in the paper two techniques for eliminating the effect of surface wave motion on the insar current estimates one method relies on some knowledge of the local wind and wave field and the use of a microwave scattering model the other method makes use of a few in situ current measurements spaced at different range locations across the insar image using either of these techniques we find that the agreement between the insar and oscr current estimates is generally very good furthermore the insar current and magnitude imagery show the presence of undulating surface features where abrupt changes in the current speed and direction occurred the ship surveys indicate that these features were caused by the collision of water masses of different density we show for the first time in this paper a high resolution area extensive vector surface current map derived from the insar of the two dimensional flow in the vicinity of these features our results demonstrate convincingly that high resolution oceanic surface current vectors can be derived from insar current measurements and that these measurements may be very beneficial for detailed studies of the dynamics of small scale surface features in regions of strong current divergences or shears

space geodesy constrains ice age terminal deglaciation the global ice 6g_c vm5a model a new model of the last deglaciation event of the late quaternary ice age is here described and denoted as ice 6g c vm5a it differs from previously published models in this sequence in that it has been explicitly refined by applying all of the available global positioning system gps measurements of vertical motion of the crust that may be brought to bear to constrain the thickness of local ice cover as well as the timing of its removal additional space geodetic constraints have also been applied to specify the reference frame within which the gps data are described the focus of the paper is upon the three main regions of last glacial maximum ice cover namely north america northwestern europe eurasia and antarctica although greenland and the british isles will also be included if peripherally in the discussion in each of the three major regions the model predictions of the time rate of change of the gravitational field are also compared to that being measured by the gravity recovery and climate experiment satellites as an independent means of verifying the improvement of the model achieved by applying the gps constraints several aspects of the global characteristics of this new model are also discussed including the nature of relative sea level history predictions at far field locations in particular the caribbean island of barbados from which especially high quality records of postglacial sea level change are available but which records were not employed in the development of the model although ice 6g c vm5a is a significant improvement insofar as the most recently available gps observations are concerned comparison of model predictions with such far field relative sea level histories enables us to identify a series of additional improvements that should follow from a further stage of model iteration

application of portable free fall penetrometer for geotechnical investigation of arctic nearshore zone the arctic is currently undergoing rapid changes with regard to sea ice extent permafrost thaw and coastal erosion in addition to hydrodynamic processes the sediments in the arctic nearshore zon

estimates of currents in the nearshore ocean region using interferometric synthetic aperture radar microwave remote sensing of the ocean surface using synthetic aperture radar sar is of great interest due to its high resolution and the potential of nearly instantaneous coverage of large areas the experience accumulated in ocean imaging by sar indicates that there are substantial difficulties in interpretation of the obtained images of ocean wave systems ocean surface currents are almost impossible to obtain from sar imagery the present paper reports on measurements of ocean surface currents based on imaging of the nearshore regions of the monterey bay using an interferometric sar the method is a modification of the conventional sar which employs two spatially separated antennas this modification allows one to construct an interferogram from the two complex images obtained by each antenna which provides direct mapping of the observed surface velocities the present results demonstrate the advantages of this novel technique in studying nearshore ocean surface dynamics in particular spatial distribution of the longshore current velocity is presented

precise chronology of the last interglacial period 234u 230th data from fossil coral reefs in the bahamas a detailed study of 238 u 234 u 230 th ages was made for different coral species from two bahamian reefs to determine the time scale of the sea level high during the last interglacial period using recently developed mass spectrometric techniques for the measurement of u and th isotopes thirty seven coral samples were analyzed in replicate typical errors at 125 ky are 1 5 ky 2 and 3 ky time intervals appear to be well resolved this high precision permits detailed chronologic study with time resolution adequate to define stages of the reef s history these data demonstrate that the time between transgression and regression of the ocean in the last interglacial was about 12 ky after which sea level fell rapidly at more than 2 m ky the high sea level stand began possibly by 132 ky and certainly by 129 ky ago when sea level reached 6 m above present mean low sea level high sea level was sustained until 120 ky and then fell rapidly this time period covers the milankovitch insolation peak at 65 n but is not sharply defined and the sea level high lasted from about 4 ky before the insolation peak to 8 ky after it we find no evidence for a double peak of sea level rise in the last interglacial episode that is high stands at both 125 and 142 ky there appears to be some discrepancy between this precise chronology for a coral reef on a tectonically stable platform and the chronology assigned to deep sea sediments the present results show that the duration of the last interglacial led to a 12 ky period of high sea level stand which is much longer than the insolation peak the study area consists of two sizeable bank barrier coral reefs of sangamon age that crop out along the coast northwest of cockburn town on san salvador island and at devil s point on great inagua island the initial stage of reef development is not revealed at either site but the main parts of both reefs are well preserved at cockburn town the beginning of the reef was marked by colonization of acropora palmata on hardground areas and possibly other corals at 132 ky ago patch reefs at the southeastern flank of the developing reef were growing by 129 to 126 ky ago by 126 to 123 ky ago the crest of the reef was formed by the frame building coral a palmata and associated patch reefs flourished along its flanks a palmata coral heads grew upward to a mean low sea level 6 m above the present one the reef began to decline as sea level dropped at about 123 to 120 ky ago near two measured profiles at devil s point the top of a rubblestone dominated by a cervicornis and patch reef corals preserved in growth position have been beveled off and represent an ancient wave cut surface 230 th ages on corals below and above this surface indicate that it was cut at about 125 1 ky ago

a 10 300 14c yr record of climate and vegetation change from haiti abstract pleistocene and holocene vegetation dynamics in the american tropics are inferred largely from pollen in continental lake sediments maritime influences may have moderated climate and vegetation changes on caribbean islands stable isotope 18 o study of a 7 6 m core from lake miragoane haiti provided a high resolution record of changing evaporation precipitation e p since 10 300 14 c yr b p the miragoane pollen record documents climate influences and human impacts on vegetation in hispaniola the 18 o and pollen data near the base of the core indicate cool dry conditions before 10 000 14 c yr b p lake miragoane filled with water in the early holocene as e p declined and the freshwater aquifer rose despite increasing early holocene moisture shrubby xeric vegetation persisted forest expanded 7000 14 c yr b p in response to greater effective moisture and warming the middle holocene 7000 3200 14 c yr b p was characterized by high lake levels and greatest relative abundance of pollen from moist forest taxa climatic drying that began 3200 14 c yr b p may have driven some mesophilic animal species to extinction the pollen record of the last millennium reflects pre columbian taino and european deforestation long term holocene vegetation trends in southern haiti are comparable to trends from continental lowland circum caribbean sites suggesting a common response to regional climate change

sea level history of the past two interglacial periods new evidence from u series dating of reef corals from south florida abstract as a future warm climate analog much attention has been directed to studies of the last interglacial period or marine isotope substage mis 5 5 which occurred 120 000 years ago nevertheless there are still uncertainties with respect to its duration warmth and magnitude of sea level rise here we present new data from tectonically stable peninsular florida and the florida keys that provide estimates of the timing and magnitude of sea level rise during the last interglacial period the last interglacial high sea stand in south florida is recorded by the key largo limestone a fossil reef complex and the miami limestone an oolitic marine sediment thirty five new high precision uranium series ages of fossil corals from the key largo limestone indicate that sea level was significantly above present for at least 9000 years during the last interglacial period and possibly longer ooids from the miami limestone show open system histories with respect to u series dating but show a clear linear trend toward an age of 120 ka correlating this unit with the last interglacial corals of the key largo limestone older fossil reefs at three localities in the florida keys have ages of 200 ka and probably correlate to mis 7 these reefs imply sea level near or slightly above present during the penultimate interglacial period elevation measurements of both the key largo limestone and the miami limestone indicate that local relative sea level was at least 6 6 m and possibly as much as 8 3 m higher than present during the last interglacial period

palaeogeography and palaeoenvironments of a tropical coastal wetland and offshore shelf during holocene submergence jamaica abstract from a series of maps representing selected holocene time periods the palaeogeography and palaeoenvironments of the coastal wetland and adjacent offshore shelf at negril western jamaica are described and discussed wetland began to form at about 8250 yr b p and went through a major expansion of surface area between 7250 and 6500 yr b p vegetation influenced by saline water formed during the earlier stages of wetland development but a significant salinity decrease occurred in the late holocene which is attributed to increased freshwater input possibly driven by climatic change discharge from rivers draining through the wetland retarded growth of a sill reef that had become established on a break of slope offshore by 8250 yr b p beach development by c 6500 yr b p and subsequent inland migration controlled lateral expansion of the wetland although its vertical build up has continued in pace with sea level rise

mangrove swamp stratigraphy and holocene transgression grand cayman island west indies abstract the island of grand cayman in the western caribbean has an extensive mangrove swamp vegetation numerous cores have been taken in and adjacent to these swamplands and these reveal that the swamps are generally underlain by a transgressive sequence of sediments the basal unit of this sequence consists of a laminated or non laminated crust formed in a subaerial environment locally these crusts are overlain by plastic mud deposited in seasonally flooded environments mangrove peat forms the upper unit of the transgression within most of the swamplands overlying the other units where these are found and reaching thicknesses of more than 4 m the final stage of marine incursion is recorded to the east of north sound where in water depths of 10 200 cm shelly mud occurs overlying mangrove peat in contrast to this to the west of north sound there is a regressive sequence in which shelly marl underlies a localised sea grass peat and mangrove peat this regressive sequence records local progradation of mangroves into marine environments the transgressive sedimentary sequence on grand cayman is similar to transgressive sedimentary sequences described from the florida everglades mangrove complex florida bay and the belize shelf on grand cayman however the stratigraphy is less complex because there are not extensive freshwater peat forming environments or intertidal and supratidal carbonate environments samples of mangrove peat were collected from the peat bedrock interface along a surveyed profile across barkers peninsula on grand cayman radiometric dating of these implies that sea level was approximately 185 cm below the present level at least 2100 years bp comparison of these dates with dates on mangrove peat from elsewhere suggests that submergence on grand cayman has taken place at a similar rate to that in florida

on balanced and unbalanced accommodation peat accumulation ratios in the cretaceous coals from gates formation western canada and their sequence stratigraphic significance coal composition was investigated by means of photometric and maceral analyses on closely spaced lithotype based strip samples over the full thickness of several paralic coal seams from the cretaceous gates formation of the western canadian sedimentary basin the aim of this investigation was to test various methods of identifying accommodation trends in coal and use them to refine sequence stratigraphic interpretation of continental sediments conventional sequence stratigraphy derives its subdivisions and significant surfaces from the records left by relative sea level oscillations these records either do not project into the continental realm or are difficult to recognise in clastic non marine sediments paralic coal seams have been selected to study this problem because they are not entirely removed from marine influence and compared with most inorganic deposits coal has stored a greater wealth of information that can be analysed at a higher level of resolution the study has led to the identification of five new surfaces with chronostratigraphic potential in the sequence stratigraphic analysis of non marine sediments two of these surfaces called paludification surface pas and terrestrialisation surface tes occur at the bases of the investigated coal seams while two other surfaces referred to as non marine flooding surface nfs and give up transgressive surface guts form the tops of the coal the fifth and probably most important new surface called the accommodation reversal surface ars is independent of any particular facies and may either coincide with some of the other surfaces or occur separately the proportion of detrital minerals has been used as the chief discriminator between different mire types and accommodation trends other useful indicators of mire type and peat dispersal have been the proportions of sporinite and inertodetrinite as well as some derived maceral and or mineral ratios e g the groundwater influence index and the tissue preservation index isometamorphic variations of telovitrinite reflectance and fluorescence as well as their coefficients of variation were also found to contribute to the identification of cyclic shifts between balanced and unbalanced accommodation peat accumulation ratios some of these cycles which are backed up by clastic stratigraphy appear to correspond to the development of shallowing upward and deepening upward parasequences superimposed high frequency low amplitude perturbations in the coal cycles relate to smaller scale accommodation cycles of sub parasequence level not always recognised in non marine strata these sub parasequence coal cycles do not always continue the shallowing upward trend typical of conventional parasequences several coals were found to contain stacks of small scale cycles with upward increasing accommodation signatures either in their lower or upper halves or over the whole seam section

mass spectrometric 234u 230th ages from the key largo formation florida keys united states constraints on diagenetic age disturbance new mass spectrometric 234 u 230 th ages for the key largo formation confirm earlier less precise alpha counting measurements that place the unit within marine oxygen isotope stage 5 ages derived from the petrographically freshest samples 99 aragonite of this study range from 125 to 138 ka despite careful sample selection and preparation the initial 234 u 238 u activity ratios denoted 234 u 238 u t range from 1 163 to 1 176 and so are all significantly higher than modern day or inferred last interglacial seawater this result indicates open system behavior of u series nuclides as has been observed in many other pleistocene coral samples and casts doubt on the accuracy of our age determinations we have used our samples to investigate the processes and magnitudes of age perturbations repeats of the same sample dissolution analytical reproducibility are within measured uncertainties which are generally less than 1 k y in contrast different parts of the same coral similarly screened for alteration can show age differences of as much as 3 k y evidence from this study and others suggests that alteration generally increases 234 u 230 th ages we were able to determine by using field relationships that the differences in 234 u 230 th ages of samples lying on either side of an erosion feature are at least 5 k y in error the stratigraphically younger corals above the erosion surface have 234 u 230 th ages that are at least 5 k y too old notably these apparently more perturbed samples have lower 234 u 238 u t ratios than the underlying corals this observation emphasizes that although 234 u 238 u t is a sensitive indicator of open system behavior the 234 u 238 u t ratio does not provide a simple index of the magnitude of age disturbance diagenetic additions of both 234 u and 230 th to corals seem necessary to explain both elevated ages and 234 u 238 u t ratios we argue that these additions result from redistribution of nuclides during meteoric alteration of the reef in the first 40 k y after formation variations in the amount of 230 th added relative to 234 u can be used to model the spread of ages at similar 234 u 238 u ratios although variable amounts of recent u loss may also have been important the youngest age of this study 125 ka just below an erosion surface is compatible with the ages of similar features in the southern bahamas we suggest that 125 ka is the maximum age of a short lived sea level lowstand within the last interglacial 5e highstand

predicting creep settlements of foundations in permafrost from the results of cone penetration tests as a joint research project sponsored by the french norwegian foundation for scientific and industrial research the norwegian geotechnical institute geodia geocean and ecole polytechnique have carried out in the summer of 1990 a series of special in situ pressuremeter and cone penetration tests at a permafrost site in longyearbyen svalbard the purpose of the testing program was to compare the results of the two different field testing methods and to check the potential of such methods for serving as a basis for prediction of the behaviour of foundations in permafrost as pressuremeter test results have been presented in a previous publication this paper shows only the results of cone penetration tests and their interpretation in terms of strength and creep parameters of the frozen soil subsequently the same data are used to predict the behaviour under long term axial load of two prefabricated and one cast in place concrete pile that were tested by the selmer furuholmen anlegg a s in cooperation w

laboratory measurements of uniform longshore currents abstract experiments on uniform longshore currents in a wave basin are described the measurements were performed in a basin with a pumped recirculation through openings in the wave guides minimal return flows in the offshore region of the basin are found to be accompanied with longshore currents which are virtually uniform alongshore three dimensional longshore current velocity distributions were measured with much attention to quality control detailed experimental results are presented for different wave fields two beach slopes and two beach roughnesses

quaternary seal level fluctuations on the netherlands antilles possible correlations between a newly composed sea level curve and local features abstract earlier published data on eustatic sea level fluctuations are used to construct a new eustatic sea level curve for the quaternary period by introducing the local uplift trend this curve is made valid for the leeward netherlands antilles the resulting new curve fits surprisingly well with local geomorphologic and petrologic features the ages of two younger coastal terraces had already been defined by using absolute dating methods the ages of two older ones are estimated applying the newly presented sea level curve

coastal changes along the coast of vere jamaica over the past two hundred years data from maps and air photographs abstract analysis of air photographs and maps indicates complex patterns of shoreline changes along the south coast of vere jamaica between the mouths of the rio minho and milk river these include up to half a kilometre of shore normal coastal recession between 1941 and 1991 the largest known shoreline change in jamaica over the past 60 years previously the coastline had been prograding seawards from a low cliff cut into the rio minho alluvial fan in the process constructing a shore parallel ridge and lagoon complex the cliff itself is evidence of earlier coastal erosion maps published in 1804 and 1885 confirm the mobility of this coastline in historical times they suggest that the more easterly complex of shore parallel lagoons was constructed prior to about 1880 while the more recent westerly beach ridges developed at least partly from progressive destruction of the lagoon complex following a change in orientation of the rio minho mouth in the late 19th century photographs of 1999 indicate the onset of accretion probably resulting from the gradual onshore movement of massive quantities of sediment deposited off the rio minho mouth during the extreme flood event of 1986 and several lesser events in 1988 and the 1990s

ice volume and sea level during the last interglacial during the last interglacial period 125 000 years ago sea level was at least several meters higher than at present with substantial variability observed for peak sea level at geographically diverse sites speculation that the west antarctic ice sheet collapsed during the last interglacial period has drawn particular interest to understanding climate and ice sheet dynamics during this time interval we provide an internally consistent database of coral u th ages to assess last interglacial sea level observations in the context of isostatic modeling and stratigraphic evidence these data indicate that global eustatic sea level peaked 5 5 to 9 meters above present sea level requiring smaller ice sheets in both greenland and antarctica relative to today and indicating strong sea level sensitivity to small changes in radiative forcing

theory of synthetic aperture radar ocean imaging a marsen view this paper reviews basic synthetic aperture radar sar theory of ocean wave imaging mechanisms using both known work and recent experimental and theoretical results from the marine remote sensing marsen experiment several viewpoints that have contributed to the field are drawn together in a general analysis of the backscatter statistics of a moving sea surface a common focus for different scattering models is provided by the mean image impulse response function which is shown to be identical to the spatially varying frequency variance spectrum of the local complex reflectivity coefficient from the analysis has emerged a more complete view of the sar imaging phenomenon than has been previously available a new generalized imaging model is proposed

coastal morphology and late quaternary history cayman islands west indies abstract instrumental surveys of coastal profiles in the cayman islands western caribbean reveal the presence of a horizontal erosional bench at 1 9 m on grand cayman and a deep horizontal notch at 6 4 m on cayman brac but no raised erosional features on little cayman each island is surrounded by a horizontal constructional raised reef usually below 2 m here dated by u series methods as 124 000 8000 yr old and hence broadly contemporary with other western atlantic raised reefs of similar elevations the different raised erosional features indicate independent vertical tectonic movement of the three islands predating the formation of the raised reef the accordance and horizontality of the raised reef indicates stability of the islands since the last interglacial times an erosional notch at present sea level has formed since the sea reached its present level less than 2100 b p and algal benches on exposed coasts are also in equilibrium with present conditions

insar imagery of surface currents wave fields and fronts the authors demonstrate the ability of interferometric radar imagery to determine both relative and absolute surface velocities in the open ocean absolute phase calibration is accomplished by noting the azimuthal displacement of range travelling targets demonstrating for the first time that under favourable circumstances phase calibration can be achieved in open ocean in the absence of ground truth the high resolution of radar imagery permits observation of sharp velocity discontinuities e g the gulf stream boundary and the wave field the recent sir c x sar shuttle missions dramatically emphasize the experimental and observational aspects of space based radar the combination of absolute velocities high spatial resolution and wide area coverage suggest that interferometric radar imagery can provide a unique and powerful aid both for studies of global circulation patterns and detailed analysis of slope shelf water interactions with ocean currents in particular the authors employ this measurement of the surface currents and wave field near a velocity front to help refine and bound results of their modeling of calculated radar images of the front the results of this paper are compared with available ground truth

on postglacial sea level summary an exact method is presented for calculating the changes in sea level that occur when ice and water masses are rearranged on the surface of elastic and viscoelastic non rotating earth models the method is used to calculate the instantaneous elastic and delayed vi scoelastic sea level changes following the partial melting of late quaternary ice sheets we find that there can be large errors in the usual assumption that changes in sea level are uniform over the ocean basins if a quantity of ice equivalent to a uniform 100 m rise in sea level melts from the laurentide and fennoscandian ice sheets then in the south pacific the instantaneous rise in sea level can be as large as 120m in the north atlantic the instantaneous rise is always less than 100 m there is a zone in the north atlantic with almost no sea level change and near greenland and norway the sea level falls rather than rises by over 100 m one thousand years after the melting a forebulge migrating towards the ice loads causes water to flow from the south pacific into the north pacific suggesting that raised beaches should occur in the south pacific the gravitational attraction of an ice mass upon a nearby ocean tends to hold sea level high in the vicinity of the ice this extra load near the ice may have a significant influence on postglacial isostatic adjustment

seismic stratigraphy of discovery bay jamaica abstract high resolution seismic reflection profiling within discovery bay jamaica has revealed that this 54 m deep subcircular reef protected coastal basin has over 100 m of relief partially buried reefal structures at a water depth of 40 m indicate a past sea level stillstand in addition side scan sonar reveals that the slopes leading down into the basin from these upper reefs are nearly acoustically featureless indicating little downslope movement by reefal debris and no slope failure the basin center is dominated by a 15 m thick upper sequence of mollusk rich carbonate mud which has accumulated at a rate of 1600 mm 1000 yrs for the past 9000 yrs based upon 14 c dates the total 50 m of basinal infilling consists of two primary sequences both approximately of the same thickness without very long cores 15 m we can only speculate on basin infilling history the deepest subsurface portion of the basin lies on line with a fault controlled dry valley and a pronounced change in the seaward reef trend the north coast of jamaica consists of a terraced limestone coastal plain we propose that discovery bay initially formed by dissolution from calcite undersaturated groundwaters focused along this fault a reefal barrier rim developed and sealed off this depression from the open caribbean sea sometime during the pleistocene a similar coastal depression rio bueno lies just to the west of discovery bay but remained open probably due to continued freshwater influx which retarded reef growth during lowstands throughout the late neogene and quaternary

remote sensing of ocean currents a method of remotely measuring near surface ocean currents with a synthetic aperture radar sar is described the apparatus consists of a single sar transmitter and two receiving antennas the phase difference between sar image scenes obtained from the antennas forms an interferogram that is directly proportional to the surface current the first field test of this technique against conventional measurements gives estimates of mean currents accurate to order 20 percent that is root mean square errors of 5 to 10 centimeters per second in mean flows of 27 to 56 centimeters per second if the full potential of the method could be realized with spacecraft then it might be possible to routinely monitor the surface currents of the world s oceans

the analysis of last interglacial mis 5e relative sea level indicators reconstructing sea level in a warmer world the last interglacial mis 5e 128 116 ka is among the most studied past periods in earth s history the climate at that time was warmer than today primarily due to different orbital conditions with smaller ice sheets and higher sea level field evidence for mis 5e sea level was reported from thousands of sites but often paleo shorelines were measured with low accuracy techniques and in some cases there are contrasting interpretations about paleo sea level reconstructions for this reason large uncertainties still surround both the maximum sea level attained as well as the pattern of sea level change throughout mis 5e such uncertainties are exacerbated by the lack of a uniform approach to measuring and interpreting the geological evidence of paleo sea levels in this review we discuss the characteristics of mis 5e field observations and we set the basis for a standardized approach to mis 5e paleo sea level reconstructions that is already successfully applied in holocene sea level research application of the standard definitions and methodologies described in this paper will enhance our ability to compare data from different research groups and different areas in order to gain deeper insights into mis 5e sea level changes improving estimates of last interglacial sea level is in turn a key to understanding the behavior of ice sheets in a warmer world

synthetic aperture radar imaging of upper ocean circulation features and wind fronts a sharp transition from dark to brighter backscatter regions the corresponding profiles of backscatter modulation across these features are expressed by a peak of about 2 db in contrast to a steplike increase of 5 8 db this suggests that sar image expressions of upper ocean circulation features and wind fronts can be distinguished and classified on the basis of this classification we attempt to quantify the dominating marine geophysical variables this method for systematic interpretation of sar images should be further validated with the use of airborne or satellite data such as from the first

internal structure and conditions of permafrost mounds at umiujaq in nunavik canada inferred from field investigation and electrical resistivity tomography a systematic approach was used for the interpretation of the electrical resistivity tomography carried out on two permafrost mounds at umiujaq in nunavik canada to assess their internal structure and conditions prior information under the form of a geocryologic model of the permafrost mounds was integrated in the inversion of the pseudo section of apparent electrical resistivity the geocryologic model was developed from the synthesis of previous field investigations including shallow and deep sampling temperature and electrical resistivity logging and cone penetration tests performed in the permafrost mounds values of electrical resistivity were ascribed to the different layers making of the geocryologic model to define a synthetic resistivity model of the permafrost mounds used as a reference model to constrain the inversion the constrained resistivity model clearly show the presence of ice rich cores in the permafrost mounds underscored by high resistivity values in excess of 30 000 m while t

sea level and deep water temperature changes derived from benthic foraminifera isotopic records we show that robust regressions can be established between relative sea level rsl data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle we then apply these regressions to long benthic isotopic records retrieved at one north atlantic and one equatorial pacific site to build a composite rsl curve as well as the associated confidence interval over the last four climatic cycles our proposed reconstruction of rsl is in good agreement with the sparse rsl data available prior to the last climatic cycle we compute bottom water temperature changes at the two sites and at one southern indian ocean site taking into account potential variations in north atlantic local deep water 18o our results indicate that a last glacial maximum lgm enrichment of the ocean mean oxygen isotopic ratio of 0 95 is the lowest value compatible with unfrozen deep waters in the southern indian ocean if local deep water 18o did not increase during glacials with respect to present such a value of the lgm mean ocean isotopic enrichment would impose a maximum decrease in local bottom water 18o at the north atlantic site of 0 30 during glacials

motion detection using near simultaneous satellite acquisitions a number of acquisition constellations for airborne or spaceborne optical images involve small time lags and produce near simultaneous images a type of data which has thus far been little exploited to detect or quantify target motion at the earth s surface these time lag constellations were for the most part not even meant to exhibit motion tracking capabilities or these capabilities were considered a drawback in this contribution we give the first systematic overview of the methods and issues involved in exploiting near simultaneous airborne and satellite acquisitions we first cover the category of the near simultaneous acquisitions produced by individual stereo sensors typically designed for topographic mapping with a time lag on the order of a minute over this time period we demonstrate that the movement of river ice debris sea ice floes or suspended sediments can be tracked and we estimate the corresponding water surface velocity fields similarly we assess cloud motion vector fields and vehicle trajectories a second category of near simultaneous acquisitions with much smaller time lags of at most a few seconds is associated with along track offsets of detector lines in the focal plane of pushbroom systems these constellations are demonstrated here to be suitable to detect motion of fast vehicles such as cars and airplanes or for instance ocean waves acquisition delays are third also produced by other constellations such as trains of satellites following each other and leading to time lags of minutes to tens of minutes which are in this contribution used to track icebergs and features of floating ice crystals on the sea and an algae bloom for all acquisition categories the higher the spatial resolution of the data and the longer the time lag the smaller the minimum speed that can be detected

tectonic and eustatic control on late cenozoic sedimentation within an active plate boundary zone west coast margin jamaica at the western margin of jamaica emergence and submergence caused by positive and negative vertical tectonic movements and glacio eustatic sea level change have initiated several phases of carbonate clastic and organic sedimentation from neogene to recent time subaerial exposure of a mid tertiary carbonate platform in the late middle miocene resulted in vadose solution of the emerged limestones creating hummocky karst topography estimates derived from limestone erosion rates and extrapolated rates of displacement of last interglacial high sea level features indicate that down faulting of an extensive coastal block commenced in the late pliocene river systems developed across the block subsequent to downfaulting depositing clay and limestone gravel in valleys incised across the platform surface during the last interglacial high sea level stand a cliff and notch were cut into the western edge of the block and reefal sediments accumulated on the terrace below continued downfaulting subsequent to the last interglacial lowered the block by as much as 24 m in places although variable depths along the notch suggest intra block faulting in contrast rapid uplift of an adjacent block to the south has brought bathyal miocene sediments to emergent levels during the course of which interaction with sea level at various times has resulted in the formation of at least four marine terraces with the last postglacial transgression a sill reef began to develop on a break of slope seaward of the cliff but it appears to have been drowned by a combination of rapid eustatic sea level rise and the introduction of reworked terrigenous detritus washed from the shelf surface by the encroaching sea inland a wetland began to form at about 8500 yr b p in response to flooding of the downfaulted platform by the rising sea and subsequent to complete holocene submergence a peat deposit as much as 18 m thick has formed a carbonate sand beach migrated eastward over the wetland during the later stages of the holocene transgression but the remainder of the submerged shelf seaward of the beach is notably lacking in holocene carbonate accumulation

global sea level fluctuations during the last interglaciation mis 5e the geomorphology and morphostratigraphy of numerous worldwide sites reveal the relative movements of sea level during the peak of the last interglaciation marine isotope stage mis 5e assumed average duration between 13072 and 11972 ka because sea level was higher than present deposits are emergent exposed and widespread on many stable coastlines correlation with mis 5e is facilitated by similar morphostratigraphic relationships a low degree of diagenesis uranium thorium u th ages and a global set of amino acid racemization aar data this study integrates information from a large number of sites from tectonically stable areas including bermuda bahamas and western australia and some that have experienced minor uplift 2 5 m 100 ka including selected sites from the mediterranean and hawaii significant fluctuations during the highstand are evident at many mis 5e sites revealed from morphological stratigraphic and sedimentological evidence rounded and flat topped curves derived only from reef tracts are incomplete and not representative of the entire interglacial story despite predictions of much different sea level histories in bermuda the bahamas and western australia due to glacio and hydro isostatic effects the rocks from these sites reveal a nearly identical record during the last interglaciation the last interglacial highstand is characterized by several defined sea level intervals slis that include sli 1 post glacial mis 6 5e termination ii rise to above present before 130 ka sli 2 stability at 2 to 3 m for the initial several thousand years 130 to 125 ka during which fringing reefs were established and terrace morphology was imprinted along the coastlines sli 3 a brief fall to near or below present around 125 ka sli 4 a secondary rise to and through 3 4 m 124 to 122 ka followed by sli 5 a brief period of instability 120 ka characterized by a rapid rise to between 6 to 9 m during which multiple notches and benches were developed and sli 6 an apparently rapid descent of sea level into mis 5d after 119 ka u th ages are used to confirm the last interglacial age of the deposits but unfortunately in only two cases was it possible to corroborate the highstand subdivisions using radiometric ages sea levels above or at present were relatively stable during much of early mis 5e and the last 6 7 ka of mis 1 encouraging a comparison between them the geological evidence suggests that significant oceanographic and climatic changes occurred thereafter midway through and continuing through the end of mis 5e fluctuating sea levels and a catastrophic termination of mis 5e are linked to the instability of grounded and marine based ice sheets with the greenland gis and west antarctic wais ice sheets being the most likely contributors late mis 5e ice volume changes were accompanied by oceanographic reorganization and global ecological shifts and provide one ominous scenario for a greenhouse world r 2007 elsevier ltd all rights reserved