successions of invertebrate microfossils and the late quaternary deglaciation of the central st lawrence lowland canada and united states abstract foraminiferal and ostracode assemblages in late glacial and early post glacial sediments of the central st lawrence lowland show that a proglacial lake glacial lake st lawrence preceded the champlain sea in some parts of the lowland and that the champlain sea was in contact with the laurentide ice sheet during deglaciation of other parts of the lowland glaciolacustrine and glaciomarine environments were followed by marine environments with salinity as high as 24 34 the higher salinity water in the champlain sea was part of a salt water wedge extending from the gulf of st lawrence into the central st lawrence lowland the beginning of the champlain sea is placed between 11 4 and 11 6 ka bp on the basis of radiocarbon ages for the arrival of the salt water wedge in the central st lawrence lowland the distribution of rhythmites associated with glacial lake st lawrence shows that subaqueous outwash fans in the ottawa area were deposited in glacial lake st lawrence rather than in the champlain sea

postglacial relative sea level histories along the eastern canadian coastline abstract we have assembled a database of relative sea level rsl data points from the eastern coast of canada from hudson bay to the border with the usa in compiling this database we have critically reviewed 1092 radiocarbon dated samples from raised beaches isolation basins intertidal and marine deposits and archaeological indicators to produce 405 sea level index points and 687 sea level limiting points our comprehensive systematic and quality controlled rsl database allowed for the reconstruction of the postglacial evolution of 34 regions of eastern canada providing new basin scale insights into the processes driving rsl changes in the last 16 ka the combination of a database of sea level index points with an innovative empirical bayesian spatio temporal statistical model provided new insights into rates and magnitude of the spatially variable glacial isostatic adjustment gia which dominated the postglacial rsl evolution in this sector of north america a continuous postglacial rsl fall is observed at latitudes 50 n with higher rates up to 35 mm a 1 recorded in southeastern hudson bay at lower latitudes the evolution is non monotonic with rsl that dropped to a spatially variable early holocene lowstand followed by a mid holocene highstand and eventually a gradual drop to present rsl this pattern is particularly evident in the st lawrence corridor along the majority of the newfoundland new brunswick and western nova scotia coasts a late pleistocene early holocene rsl lowstand was followed by a continuous rise through the holocene at the margin of the former ice sheet i e eastern nova scotia our data identify a continuous rsl rise through the holocene these records are characterized by decreasing rates of rsl rise through time commencing with a rapid rise during the early holocene up to 17 mm a 1 a slowdown in the mid holocene average rates 9 mm a 1 and a further reduction in the late holocene average rates

relative sea level rise and tidal development in the fundy tidal system previous studies of sea level and tidal amplification in the bay of fundy suggested a linear increase of tidal amplitude as relative sea level rose new data presented here are used in a numerical tidal model in an effort to reproduce paleotidal regimes over the last 7000 years five new sea level curves covering the last 4000 years and some previously published data extending the record back to 7000 years before present bp are used as the data base these data when used together with the tidal model indicate that tidal amplitudes increased much more rapidly between 7000 and 4000 years ago than in the period 4000 years ago to present it is also shown that changes in depth within the bay of fundy produce little effect on the tidal amplitudes whereas such variations in water depth on georges bank account for almost all the change this calculation of tidal amplitude changes allows calibration of sea level curves to be made for the bay of fundy using higher high water hhw indicators

micropaleontological documentation for early holocene fall of relative sea level on the atlantic coast of nova scotia the presence of a marsh sequence between two shallow water marine deposits in an offshore core from lunenburg nova scotia indicates fall of relative sea level followed by rise of relative sea level the marsh sequence is now 27 m below datum level with a c 14 date of 7 070 yr b p this sequence suggests that the glacial forebulge migrated through this area 7 000 yr ago that 27 m of submergence has occurred since then and that prior to 7 000 yr b p the site was characterized by low amplitude emergence this is at present the only sequence where the entire regression transgression record is preserved along this coast the accuracy required to demonstrate this can be obtained only by using established marsh foraminiferal zonations

the detection of low magnitude seismic events using array based waveform correlation summary it has long been accepted that occurrences of a known signal are most effectively detected by cross correlating the incoming data stream with a waveform template such matched signal detectors have received very little attention in the field of detection seismology because there are relatively few instances in which the form of an anticipated seismic signal is known a priori repeating events in highly confined geographical regions have been observed to produce very similar waveforms and good signals from events at a given site can be exploited to detect subsequent co located events at lower magnitudes than would be possible using traditional power detectors even greater improvement in signal detectability can be achieved using seismic arrays running correlation coefficients from single sensors can be stacked over an array or network to result in a network correlation coefficient displaying a significant array gain if two events are co located the time separating the corresponding patterns in the wave train as indicated by the cross correlation function is identical for all seismic stations and this property means that the correlation coefficient traces are coherent even when the waveforms are not we illustrate the power of array based waveform correlation using the 1997 august 16 kara sea event the weak event that occurred 4 hr after the main event was barely detected using an sta lta detector on the spits array but is readily detected by signal matching on a single channel the main event was also recorded by the far more distant norsar array but no conventional detection can be made for the second event a clear detection is however made when the correlation coefficient traces are beamformed over all sensors of the array we estimate the reduction in detection threshold of a test signal on a regional seismic array using waveform correlation by scaling down a master signal and immersing it into seismic noise we show that for this case waveform correlation using a single channel detects signals of approximately 0 7 orders of magnitude lower than is possible using an sta lta detector on the array beam waveform matching on the full array provides an additional improvement of approximately 0 4 magnitude units we describe a case study in which small seismic events at the barentsburg coal mine on spitsbergen were detected using the signals from a major rockburst as master waveforms many spurious triggers occurred in this study whereby short sections of signal exhibited coincidental similarity with unrelated incoming wave fronts we demonstrate how such false alarms can almost always be identified and screened out automatically by performing frequency wavenumber analysis upon the set of individual correlation coefficient traces

recent saltmarsh foraminiferal assemblages from iceland abstract this study reports for the first time boreal to subarctic intertidal foraminiferal assemblages from saltmarshes at borgarnes and faskrudsfjordur on iceland the composition of living and dead foraminiferal assemblages was investigated along transects from the tidal flat to the highest reach of halophytic plants the foraminiferal assemblages from borgarnes showed 18 species in the total foraminiferal assemblage of which only 7 species were recorded in the living fauna the assemblages were dominated by agglutinated taxa whereas 3 calcareous species were recorded of which only haynesina orbicularis was found in the living fauna the distribution limit of calcifying species corresponds to the lower boundary of the lower saltmarsh vegetation zone furthermore calcareous tests showed many features of dissolution which is an indication of a carbonate corrosive environment the species forming the dead assemblages were mainly derived from the ambient intertidal areas and were displaced by tidal currents into the saltmarsh the foraminiferal assemblages from faskrudsfjordur showed two species of which only one species was recorded in the living fauna the assemblage was dominated by the agglutinated foraminifer trochaminita irregularis the foraminiferal species recorded on iceland were the same as commonly found elsewhere in europa since no species was found which is endemic to north america iceland is considered part of the european bio province the foraminiferal could have been immigrated to iceland from europe through warm water currents migratory birds or marine traffic since the last ice age

palaeogeography of atlantic canada 13 0 kyr abstract we combine isobase maps with a digital terrain model of atlantic canada to map coastlines from 13 14c kyr bp to the present at 13 14c kyr bp there are ridges of high relative sea level rsl values over newfoundland and the maritime provinces and a re entrant of low values in the gulf of st lawrence this pattern persists well into the holocene and reflects crustal response to the slow wasting of ice caps that persisted in newfoundland and the maritime provinces for up to five millennia after the removal of ice from the gulf of st lawrence by a migrating calving embayment the palaeogeographic reconstructions reveal an archipelago on the outer shelf from grand bank to the continent that persisted from 13 14c kyr bp until ca 8 14c kyr bp much of the magdalen shelf was exposed but the magdalen islands were never connected to the mainland prince edward island was initially separated from the mainland became connected after 11 14c kyr bp and was separated again just before 6 14c kyr bp when northumberland strait formed the reconstructions are highly sensitive to relatively small changes in isobase values especially on the shallow banks on the continental shelf

salt marsh sea level indicators and transfer function development for the magdalen islands in the gulf of st lawrence canada abstract late holocene salt marsh sediments allow the reconstruction of pre industrial relative sea level changes typically reconstructions are derived by quantifying a relationship between contemporary proxies and elevation which is then applied to down core fossil assemblages via a transfer function common sea level indicating proxies are salt marsh foraminifera and diatoms however testate amoebae represent an alternative complementary proxy with current sea level research increasingly invoking multi decadal timescale processes such as ocean current strength or wind stress to explain relative sea level changes there is a need for increased vertical precision in reconstructions this paper presents new surface assemblages of salt marsh foraminifera and testate amoebae with respect to elevation from two coastal locations in the magdalen islands in the gulf of st lawrence eastern canada we analyse the suitability of each proxy for reconstructing sea level using multivariate statistics ordination and regression modelling testate amoebae are found in greater abundance and diversity than foraminifera and their assemblage variations can be better accounted for by changes in elevation the contemporary training sets from the magdalen islands were able to predict marsh surface elevations viz sea level to precisions of 0 08 m and 0 12 m for testate amoebae and foraminifera respectively there were no benefits from combining the two proxies into a unified training set it was possible to improve the performance of the foraminifera based transfer function by incorporating a second dataset from newfoundland which served to increase the range of the sampled environment and improve the correlation coefficient between sample elevations and model predictions in accordance with existing literature we find transfer function performance to be better at locations with smaller tidal ranges

morphology and seismic stratigraphy of the inner continental shelf off nova scotia canada evidence for a 65 m lowstand between 11 650 and 11 250 c14 yr b p abstract nova scotia s position near the margin of large pleistocene ice sheets makes the scotian shelf region critical for evaluation of glaciation models and sea level change the sea floor of the inner scotian shelf was mapped using multibeam bathymetry a combination of conventional seismic and sonar techniques and sampling multibeam bathymetry provides an areal image of the sea floor combining this unique image with sub bottom seismic imaging the relationships between sea floor topography and the underlying strata were explored the inner continental shelf of nova scotia can be subdivided into five major terrain zones these are the 1 truncation zone 2 morainal zone 3 outcrop zone 4 basin zone and 5 scotian shelf end moraine complex the scotian shelf end moraine complex and basin zone are glacial depositional zones at the seaward edge of the inner shelf landward of these zones is a region of high relief bedrock with ridges and valleys largely devoid of surficial sediments extending from 80 to 120 m water depth outcrop zone this zone is interpreted as a relict bedrock surface preserved under frozen bed glacier conditions to the east of the outcrop zone in similar water depths are unmodified till ridges overlying bedrock morainal zone the truncation zone is a region of the inner shelf from 90 m to the present shoreline characterized by muted acoustic topography and planar erosional surfaces truncating bedrock and surficial sediments the truncation zone is subdivided into the valley subzone the transition subzone the platform subzone and the estuarine subzone the valley subzone is typified by sediment infilled valleys occurring in 75 to 90 m water depths these valleys contain seismic facies with a ponded style of deposition planed off at the sea floor or by erosional unconformities near the sea floor the transition subzone is marked by a relatively steep ramp and terraces the ramp at the type section extends from 75 to 65 m water depth the surface of the ramp can be either an erosional unconformity or a depositional surface formed by clinoform beds the 65 m former shoreline is interpreted as the top of the transition subzone ramp surface at one ramp locality clinoform beds form part of a progradational sequence called the sambro delta a mussel valve fragment mytilus edulis was obtained from a core in the foresets and radiocarbon dated an age of 11 650 110 yr b p was obtained adjusted for isotopic fractionation above 65 m the sea floor forms a low relief gently sloping erosional surface platform subzone estuarine deposits have been found above 50 m the new sea level curve constructed with the dated 65 m shoreline and recently published data is at variance with calculated rsl curves based on geophysical models primarily in the amplitudes and rates of rsl change reasons for the discrepancies may be late melting ice and regional variations in lithospheric strength and thickness

a technique for identifying microseismic multiplets and application to the valhall field north sea a fast fully automatic technique to identify microseismic multiplets in borehole seismic data is developed the technique may be applied in real time to either continuous data or detected event data for a number of three component receivers and does not require prior information such as p or s wave time picks peak crosscorrelation coefficients evaluated in the frequency domain are used as the basis for identifying microseismic doublets the peak crosscorrelation coefficient at each receiver is evaluated with a weighted arithmetic average of the normalized correlation coefficients of each component each component is weighted by the maximum amplitude of the signal for that component to reduce the effect of noise on the calculations the weighted average correlations are averaged over all receivers in a time window centered on a fixed lag time the size of the time window is determined from the dominant period in the signal and the lag time is the time that maximizes the average correlation coefficient the technique is applied to a three component passive seismic data set recorded at the valhall field north sea a large number of microseismic doublets are identified that can be grouped into multiplets reducing the total number of absolute event locations by a factor of two seven large multiplets reflect the repeated multiple rerupturing up to 30 times on a single fault and significant stress release two major faults dominate the seismic activity causing at least one fourth of the observed events

surficial sediments of the outer banks scotian shelf canada the distribution thickness and mean grain size of surficial sediments on sable island bank middle bank and banquereau scotian shelf are used to re evaluate interpretations made by others on mechanisms controlling long term stability and net transport pathways of surface sand a holocene sand ridge complex the sable island catena extends 300 km across sable island bank and banquereau this sand ridge complex which is up to 50 m thick formed as a result of holocene sediment transport on the outer banks and controls the modern day distribution of bedforms and sediment size a clockwise circulation of sand centred around sable island which had been proposed as the mechanism maintaining the island does not take place sand is transported from southwest to northeast across sable island bank towards the sable island catena thereafter sand is dispersed eastward spillover of sand from the banks to the gully is not significant sand is trapped in depths less than 100 m the processes proposed to ha

behaviour and taphonomic loss in foraminiferal assemblages of mangrove swamps of french guiana abstract fifty three surface sediment samples were collected in january 1999 july 2000 and december 2000 on mud flats and in mangrove swamps of french guiana sampling stations were selected to provide information on different environmental conditions on the mud flats and in the mangrove forest thirteen samples were also collected at a depth of about 8 12 cm in the sediment additional samples were collected from three long cores in the channel of the kaw river the main parameter controlling the distribution of recent foraminiferal assemblages is the seasonally variable relative influence of coastal water of reduced salinity and low ph low ca river water areas under the influence of coastal water are dominated by calcareous species mainly ammonia tepida and cribroelphidium spp even in mangrove swamps during the dry season river water influences almost all the study area during the rainy season and leads to the dominance of agglutinated species with the nature of the assemblages depending on local environmental characteristics on the mud flats tests are typically well preserved in the 10 cm below the surface that is the most important taphonomically active zone for foraminifera however owing to intense bioturbation the taphonomic processes in the mangrove swamp may result in the total destruction of the microfauna including agglutinated tests this study shows that the preservation of thanatocoenoses in mangrove swamp environments of french guiana only occurs in exceptional circumstances when they are preserved the remaining assemblages even if modified by taphonomic processes give valuable information for paleoenvironmental reconstructions in this environment

erratum postglacial relative sea level change port au port area west newfoundland we first report pollen and foraminifera analyses and radiocarbon dates from two cores taken from salt marsh deposits bordering port au port bay southwestern newfoundland results show that relative sea level rsl stood at 2 8 m below present higher high water level hhwl at 2770 300 years bp and at 1 8 m at 2365 175 years bp at the core sites they permit calculation of a rate of late holocene rsl change from western newfoundland we then report other available dates bearing on the earlier rsl record of this area a date of 5800 200 years bp fixes the age of minimum rsl in port au port bay at 11 14 m below present a date of 9350 120 years bp from st george s provides a minimum age for the passage of sea level below present there a date of 12 600 140 years bp from stephenville fixes a sea level at 29 m above present whereas one of 13 600 110 years bp from abrahams cove dates the marine limit at 44 m these geographically restricted data closely constrain a curve of postglacial rsl change

salt marsh aggradation in response to late holocene sea level rise at amherst point nova scotia canada a radiocarbon 14c chronology determined for plant macrofossils in exposed salt marsh sediments at amherst point nova scotia canada shows that the edge of the high salt marsh aggraded 7 5 m since 900 bc equivalent to a mean rate of 25 9 cm 100 yr 1 four phases of rapid aggradation 900 600 bc 100 bc ad 200 ad 700 1100 and ad 1600 to present were interspersed with three phases of slower aggradation 600 100 bc ad 200 700 and tentatively ad 1100 1600 the stepped pattern of marsh aggradation probably resulted from eustatic sea level fluctuations superimposed on background signals of crustal subsidence and tidal range expansion because the rate of high salt marsh aggradation lagged or exceeded the rate of higher high water hhw increase at various times the high salt marsh aggradation trend only approximates the trend of hhw increase the eustatic sea level fluctuations are estimated to have a range of at least 0 8 m

shoreface translation and the holocene stratigraphic record examples from nova scotia the mississippi delta and eastern australia abstract classic descriptive models of barrier sedimentation have been developed with data from the atlantic and gulf coasts of the united states these models are dominated by low to moderate rates of relative sea level rsl rise and wave energy barriers respond by landward recycling of sediment through the mechanism of shoreface retreat sedimentation processes on the central coast of new south wales n s w australia consist of rapid rsl rise in early holocene times followed by a stillstand since 6500 b p wave energy is relatively high year round and sand sources for barrier formation are only found on the inner shelf barrier sedimentation on the central coast of n s w exhibits a thick composite sequence composed of a basal marine transgressive sand overlain by regressive beach and dune facies the louisiana coast surrounding the mississippi delta is underlain by compacting deltaic muds which generate very rapid rates of rsl rise the louisiana coast experiences low wave energy punctuated by high energy tropical and extra tropical storm events barrier sediments accumulate from the erosion of deltaic headlands and undergo a transformation from subaerial barrier island systems to subaqueous shoals located on the inner shelf drumlins experience coastal erosion on the eastern shore of nova scotia and provide a sediment source for compartmented estuary mouth barriers an ongoing moderate rise of rsl results from the passage of a glacial forebulge wave energy is intermediate between louisiana and n s w and displays a seasonal pattern dominated by frequent winter storms coastal barrier sedimentation is episodic consisting of a period of beach ridge progradation followed by barrier destruction and re establishment further landward the three contrasting sedimentary sequences found in examples from louisiana n s w and nova scotia indicate that presently available sedimentation models from locations such as the middle atlantic or texas coasts of the united states may only represent well documented regional case studies a true generalised coastal sedimentation model is required which can identify the parameters controlling vertical and horizontal translation of the depositional surface and provide relationships between these parameters which quantitatively predict the genesis distribution and geometry of coastal sedimentary facies

the postglacial relative sea level lowstand in newfoundland relative sea level in coastal regions of newfoundland fell from late glacial maximum levels to postglacial minima in several phases i an early period of high relative sea level when late wisconsinan ice was at the coast and discharging meltwater plumes into the ocean ii a period of rapidly falling relative sea level during which glaciers retreated inland and iii a period without glacier ice during which relative sea level continued to fall but at decreasing rates falling relative sea level caused fluvial incision of glacial deposits in some coastal embayments and culminated with the construction of lowstand marine deltas these deltas were submerged during the subsequent holocene transgression seismic reflection data from selected deltas show that they comprise wedges of sediment with prograded seaward dipping foreset style internal reflections the depth of the relative sea level lowstand varies spatially and it was diachronous it occurred relatively early and deep in peripheral regio

holocene rise of relative sea level at sable island nova scotia canada a 7 000 yr record of continuous sea level rise has been obtained from sable island nova scotia on the outer edge of the nova scotian shelf the data are unique in that this is the first continuous sea level curve obtained offshore from a former glacial ice margin the sea level data indicate a uniform rate of relative rise over the past 7 000 yr offshore contrasting sharply with onshore data that show a marked reduction in the rate of rise from 2 500 yr ago to present these observations appear to confirm recent theoretical models that suggest that sea level changes along former ice margins can be divided into zones depending on the distance from the former ice center

a comparison of present sea level linear trends from tide gauge data and radiocarbon curves in eastern canada abstract a comparison is made of the results for determinations of vertical crustal movements by means of two independent sources of data widely used in geodesy and geology tide gauge sea level linear trends and gradients of radiocarbon curves as a reference the map of vertical crustal movements of canada is added which was computed using not only tide gauge data but also geodetic levelling data these results show similar trends computed by both techniques but an average value of 0 1 m century greater for the sea level trends the map of vertical crustal movements is in good agreement with the trends provided by the gradients of radiocarbon curves

an improved method for hydrofracture induced microseismic event detection and phase picking the ability to detect small microearthquakes and identify their p and s phase arrivals is a key issue in hydrofracture downhole monitoring because of the low signal to noise ratios s n an array based waveform correlation approach matched filter is applied to improve the detectability of smallmagnitudeeventswithmechanismsandlocationssimilar to a nearby master event after detecting the weak events a transformed spectrogram method is used to identify the phase arrivals the technique has been tested on a downhole monitoring data set of the microseismic events induced by hydraulic fracturing it is shown that for this case one event with a s n around 6 db which is barely detectable using an array stacked short time average long time average sta lta detector under a reasonable false alarm rate is readily detected on the array stacked correlation traces the transformedspectrogramanalysisofthedetectedeventsimproves p ands phasepicking

an automatic phase picker for local and teleseismic events an automatic detection algorithm has been developed which is capable of time p phase arrivals of both local and teleseismic earthquakes but rejects noise bursts and transient events for each signal trace the envelope function is calculated and passed through a nonlinear amplifier the resulting signal is then subjected to a statistical analysis to yield arrival time first motion and a measure of reliability to be placed on the p arrival pick an incorporated dynamic threshold lets the algorithm become very sensitive thus even weak signals are timed precisely during an extended performance evaluation on a data set comprising 789 p phases of local events and 1857 p phases of teleseismic events picked by an analyst the automatic picker selected 66 per cent of the local phases and 90 per cent of the teleseismic phases the accuracy of the automatic picks was ideal i e could not be improved by the analyst for 60 per cent of the local events and 63 per cent of the teleseismic events

new data from halifax harbour paleoenvironment and a new holocene sea level curve for the inner scotian shelf two vibracores collected from halifax harbour allow reevaluation of the early postglacial history and part of a new sea level curve for eastern nova scotia an acoustically distinct seismic unit fo

taphonomy of salt marsh foraminifera an example from coastal georgia abstract in salt marshes of st catherines island georgia total foraminiferal density decreases significantly within the top 10 cm of marsh sediment selective preservation impacts both calcareous and agglutinated taxa calcareous taxa are removed through dissolution and agglutinated ones through bacterial degradation of cements or predation shallow to deep infaunal taxa generally are the most likely to be preserved although miliammina fusca and ammotium spp all epifaunal to shallow or intermediate infaunal dwellers have cements that are highly susceptible to degradation in southeastern u s marshes total foraminiferal density in both surface and subsurface sediment is higher in the low marsh than either the transitional or high marsh zones selective preservation and downcore enrichment by some infaunal taxa alters the percent abundance of some paleoenvironmentally significant taxa in subsurface assemblages the best baseline for paleoenvironmental studies using salt marsh foraminifera in these settings is not the marsh surface 0 1 cm but rather assemblages preserved 10 cm below the marsh surface

electric study of fracture anisotropy at falkenberg germany electric and electromagnetic methods have been applied for mapping subsurface fractures and the directional dependence of in situ electric parameters at the hot dry rock site at falkenberg germany this study includes the determination of several anisotropy parameters like the mean longitudinal and transverse resistivity components m x1d4c1 and t respectively the anisotropy coefficient and the strike angle terrain conductivity measurements using the technique of frequency domain electromagnetic induction reveal a dominant anomaly strike of east south east west north west nearly parallel to the fracturing strike of n110 with increasing distance from the central borehole the mise a la masse potential differences exhibit a transition from a direct to a paradoxical relationship to the resistivity anisotropy induced by the fracturing these observations are explained using a model for an ellipsoidal fracture the qualitative interpretation of the sounding data of schlumberger and crossed square

detection of repeated hydraulic fracturing out of zone growth by microseismic monitoring hydraulic fracture treatments are commonly carried out in several space and time staggered stages which are designed to stimulate isolated segments of a reservoir i e multistage fracturing however repeated hydraulic fracturing of reservoir segments fractured in previous stages is commonly observed in multistage fracturing this problem is also known as out of zone or out of pay growth and we shall call it cross stage fracturing in this article cross stage fracturing can be detected by automated identification of multiplets i e microseismic events with similar source mechanisms and nearly identical location we applied multiplet identification to detect cross stage fracturing on two hydraulic fracture monitoring data sets canyon sand and barnett shale formations one of which is described in this paper we verified this detection method with the initial microseismic events locations cross stage fracturing was detected only a few minutes after the first microseismic events had been detected an

late holocene sea level change in arctic norway abstract relative sea level data from the pre industrial era are required for validating geophysical models of glacio isostatic adjustment as well as for testing models used to make sea level predictions based on future climate change scenarios we present the first late holocene past 3300 years relative sea level reconstruction for northwestern norway based on investigations in south hinnoya in the vesteralen lofoton archipelago sea level changes are reconstructed from analyses of salt marsh and estuarine sediments and the micro organisms foraminifera and testate amoebae preserved within the indicative meaning of the microfauna is established from their modern distributions records are dated by radiocarbon 201pb 137cs and chemostratigraphical analyses our results show a continuous relative sea level decline of 0 7 0 9 mm yr 1 for south hinnoya during the late holocene the reconstruction extends the relative sea level trend recorded by local tide gauge data which is only available for the past 25 years our reconstruction demonstrates that existing models of shoreline elevations and gia overpredict sea level positions during the late holocene we suggest that models might be adjusted in order to reconcile modelled and reconstructed sea level changes and ultimately improve understanding of gia in fennoscandia

late glacial stratigraphy and history of the gulf of st lawrence reply the three dimensional configuration of the quaternary sediments in the gulf of st lawrence is described based on analysis of 8000 km of high resolution seismic reflection data complemented by anal

late quaternary relative sea level change in the western gulf of maine evidence for a migrating glacial forebulge new radiocarbon dated cores obtained by vibracorers in the western gulf of maine confirm that a short lived relative sea level lowstand of 55 m occurred at 11 10 5 ka these cores and younger salt marsh data also reveal that rates of transgression varied throughout the holocene probably due to local variations in glacial isostasy the isostatic component is resolved by subtracting published approximations of eustatic sea level from our well determined observations of local relative sea level a large peak in the isostatic curve coincides with the lowstand and is interpreted as a forebulge 20 25 m in amplitude forebulge migration is estimated at 7 11 km 100 yr based on the timing of lowstands across the region

simple relative space time scaling of electrical and electromagnetic depth sounding arrays implications for electrical static shift removal and joint dc tem data inversion with the most squares criterion a simple scaling relationship is shown to facilitate comparison correlation and integration of data recorded using the common experimental configurations in electrical and electromagnetic depth sounding applications of the scheme to field data from typical geological and landfill environments show that it is robust and where transient electromagnetic tem data are available enables easy identification and quantification of electrical static shift galvanic distortion in magnetotelluric and direct current dc sounding curves tem based procedures are suggested for both the direct removal of static shift in dc sounding curves and effective joint data inversion with the most squares criterion in the presence of static shift a case study of aquifer characterization using sounding data from borehole sites in the vale of york in england shows that static shift is a common problem in this glacial covered terrain and demonstrates the effectiveness of the proposed joint dc tem inversion strategy in handling distorted soundings

shallow water pockmark formation in temperate estuaries a consideration of origins in the western gulf of maine with special focus on belfast bay abstract a systematic mapping program incorporating more than 5000 km of side scan sonar and seismic reflection tracklines in the western gulf of maine has identified more than 70 biogenic natural gas deposits occupying 311 km2 in nearshore muddy embayments many of these embayments also contain pockmark fields with some exhibiting geologically active characteristics including the observance of plumes of escaping fluids and sediment pockmarks hemispherically shaped depressions of various size and depths formed through fluid escape of gas and or pore water are sometimes found within or outside gas fields although many gas fields lack pockmarks altogether although the origin of the natural gas remains unclear if coastal environments at times of lower sea level were similar to the present numerous lake wetland valley fill and estuarine sources of organic rich material may have formed on the inner shelf if these deposits survived transgression and remain buried they are potential gas sources intensive mapping of the belfast bay pockmark field in 1998 produced the first nearly continuous side scan sonar mosaic of a gulf of maine pockmark field with a corresponding 3 dimensional geological model generated from seismic data statistical analysis of pockmark geometry gas deposit loci and subsurface evidence for gas enhanced reflectors suggest that gas migration from deeper lateral sources along permeable subsurface strata may be the mechanism for pockmark formation in areas lacking gas curtain seismic reflections the coarse grained transgressive ravinement unconformity between pleistocene glacial marine mud and holocene mud may act as a conduit for distributing methane to the field s margins

joint inversion of geophysical data summary by jointly inverting several different kinds of geophysical measurements at a site we avoid some of the ambiguity inherent in the individual methods we show how this can be done for the combination of dc resistivity and magnetotelluric measurements on a layered medium by considering a simple 3 layer model the combination resolves the resistivity of the thin resistive second layer even though neither of the two methods can do so alone the method is then applied to field data from a shallow sedimentary basin a blind zone occurs beneath a thick near surface conductive shale by a study of the eigenvalue structure of the model it can be seen that resolution in this zone would be slightly enhanced by higher frequency magnetotelluric data but additional dc data at larger spacing would yield no improvement

regional aquifer mapping using combined ves tem amt emap methods in the semiarid eastern margin of parnaiba basin brazil as part of a program to evaluate the utility of integrated geoelectrical methods for subsurface structural mapping and groundwater resource investigation in the semiarid eastern margin of the parnaiba basin in brazil several vertical electrical soundings ves and transient electromagnetic tem and tensorial audio magnetotelluric amt measurements were carried out along a 250 km long east west transect passing through major towns and cities and a 127 km long north south profile passing through small farm settlements the various data sets have been jointly processed using a novel integration scheme and a constrained 1 d inversion technique to yield the resistivity structure underneath each observation station regularized 2 d inversion of static shift corrected dual mode amt data provided additional deep structural information and together with the joint 1 d results enabled an assessment of the distribution of aquifers and major structural controls in the region the east west regional geoelectrical model evokes a picture of a gently dipping succession of conductive and resistive units in good agreement with the alternating shaly and sandy formations evinced from preexisting borehole data and previous geological studies the geoelectric models also show the presence of the large scale transbrazilian lineament and other graben like structures previously inferred from aeromagnetic data which may have some control on groundwater distribution the agreement with geology and aeromagnetic interpretation emphasizes the importance of integrated geoelectrical surveying as a complementary or independent means of obtaining useful stratigraphic and structural information for hydrogeological studies in this region

differentiating anisotropy and lateral effects using azimuthal resistivity offset wenner soundings azimuthal resistivity surveys increasingly are being used by hydrogeologists in the identification and characterization of fractured rocks in these investigations electrical resistivity is measured as a function of azimuth about a fixed central point in most recent published examples any observed change in apparent resistivity with azimuth is interpreted as being indicative of fracture anisotropy however interpretation of rotational sounding data is actually more complicated as azimuthal variations in apparent resistivity are also produced by the presence of dipping stratigraphy and other lateral changes in formation resistivity such effects are generally overlooked because the field techniques normally employed are incapable of detecting them consequently it is quite probable that the results of many published surveys have been wrongly interpreted an alternative field procedure and interpretation methodology has been developed to differentiate anisotropy dipping layers and lateral effects this approach makes use of the offset wenner technique and examines the different responses of the individual wenner resistances above different geological structures analysis of data obtained using the azimuthal offset wenner technique from sites in britain and ireland have successfully identified subsurface structures and determined the anisotropy where it is present

modeling the contribution of m2 tidal amplification to the holocene rise of mean high water in the gulf of maine and the bay of fundy abstract increase in the m2 principal lunar semi diurnal component of the tidal range is an important contributor to the postglacial rise of the high tide level in the gulf of maine and the bay of fundy in addition to relative sea level rise the increase occurred as the shape of this semi enclosed embayment changed with sea level rise and its natural period approached resonance with the m2 tide a three dimensional tide model 3dens predicts the following m2 tidal ranges averaged for the gulf of maine bay of fundy as a percentage of the present range 54 59 at 7000 yrs b p 73 at 5000 yrs b p 78 at 4000 yrs b p 85 at 3000 yrs b p 94 at 2000 yrs b p and 98 at 1000 yrs b p with a predicted sea level rise of 0 15 0 90 m by the year 2100 m2 tidal range may increase 0 3 1 9

holocene relative sea level fluctuations in the st lawrence estuary quebec canada abstract between 7000 and 6000 yr b p relative sea level was as much as 5 m lower than today in the st lawrence estuary quebec a small transgression laurentian transgression occurred between 5800 and 4400 yr b p which resulted in the construction of an 8 to 10 m terrace about 3000 yr b p relative sea level was similar to present and then a stillstand or a slight rise occurred during which a cliff micmac cliff was cut into the emerged terrace during a subsequent lowering of relative sea level coastal emergence a low aggradational terrace mitis terrace was built between 2300 and 1500 yr b p at the base of the micmac cliff a new emergence curve for the south shore of the st lawrence estuary showing a mid holocene high stand of relative sea level is therefore proposed

three dimensional joint inversion for magnetotelluric resistivity and static shift distributions in complex media accurate interpretation of magnetotelluric mt data in the presence of static shift arising from near surface inhomogeneities is an unresolved problem in three dimensional 3 d inversion while it is well known in 1 d and 2 d studies that static shift can lead to erroneous interpretation how static shift can influence the result of 3 d inversion is not fully understood and is relevant to improved subsurface analysis using the synthetic data generated from 3 d models with randomly distributed heterogeneous overburden and elongate homogeneous overburden that are consistent with geological observations this paper examines the effects of near surface inhomogeneity on the accuracy of 3 d inversion models it is found that small scale and shallow depth structures are severely distorted while the large scale structure is marginally distorted in 3 d inversion not accounting for static shift thus the erroneous near surface structure does degrade the reconstruction of smaller scale structure at any depth however 3 d joint inversion for resistivity and static shift significantly reduces the artifacts caused by static shifts and improves the overall resolution irrespective of whether a zero sum or gaussian distribution of static shifts is assumed the 3 d joint inversion approach works equally well for situations where the shallow bodies are of small size or long enough to allow some induction such that the effects of near surface inhomogeneity are manifested as a frequency dependent shift rather than a constant shift

an effective noise suppression technique for surface microseismic data abstractthe presence of strong surface wave noise in surface microseismic data may decrease the utility of these data we implement a technique based on the distinct characteristics that microseismic signal and noise show in the p domain to suppress surface wave noise in microseismic data because most microseismic source mechanisms are deviatoric preprocessing is necessary to correct for the nonuniform radiation pattern prior to transforming the data to the p domain we employ a scanning approach similar to semblance analysis to test all possible double couple orientations to determine an estimated orientation that best accounts for the polarity pattern of any microseismic events we then correct the polarity of the data traces according to this pattern prior to conducting signal noise separation in the p domain we apply our noise suppression technique to two surface passive seismic data sets from different acquisition surveys the first data set includes a synthetic microseismic event added

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

integrated high precision analyses of holocene relative sea level changes lessons from the coast of maine a suite of salt marsh peat samples from four sites along the coast of maine wells phippsburg gouldsboro and machiasport has been analyzed using high precision techniques to determine local relative sea level trends and to evaluate proposed along coast warping a spatially variable set of relative sea level records in maine would have important implications for geophysical models that predict the response of the lithosphere during deglaciation and postglacial isostatic relaxation the amplification of m sub 2 tidal range in the gulf of maine and the bay of fundy during the holocene is modeled and applied to the mean high water data yielding best estimate envelopes of mean tide level change for each location average long term thousands of years mean tide level rise did not exceed approx 2 mm yr at any time during the late holocene at wells phippsburg and machiasport between 4 5 and 3 ka calibrated cal the apparent rate of rise at gouldsboro was higher than at any other site studied this along coast variation in the rate of mean tide level rise may reflect time of deglaciation neotectonics or differential isostatic adjustments a slight acceleration of mean tide level rise has occurred during the past millennium in gouldsboro and machiasport if 12 m downwarping inmore easternmost maine occurred as suggested in other publications it must have happened prior to 5 7 ka cal 84 refs 13 figs 8 tabs less

the north atlantic atmosphere sea surface 14c gradient during the younger dryas climatic event abstract we attempt to quantify the 14c difference between the atmosphere and the north atlantic surface during a prominent climatic period of the last deglaciation the younger dryas event yd our working hypothesis is that the north atlantic may have experienced a measurable change in 14c reservoir age due to large changes of the polar front position and variations in the mode and rate of north atlantic deep water nadw production we dated contemporaneous samples of terrestrial plant remains and sea surface carbonates in order to evaluate the past atmosphere sea surface 14c gradient we selected terrestrial vegetal macrofossils and planktonic foraminifera neogloboquadrina pachyderma left coiling mixed with the same volcanic tephra the vedde ash bed which occurred during the yd and which can be recognized in north european lake sediments and north atlantic deep sea sediments based on ams ages from two norwegian sites we obtained about 10 300 yr bp for the atmospheric 14c age of the volcanic eruption foraminifera from four north atlantic deep sea cores selected for their high sedimentation rates 10 cm kyr 1 were dated by ams 21 samples for each core the raw 14c ages assigned to the ash layer peak is significantly older than the 14c age obtained on land part of this discrepancy is due to bioturbation which is shown by numerical modelling nevertheless after correction of a bioturbation bias the mean 14c age obtained on the planktonic foraminifera is still about 11 000 11 100 yr bp the atmosphere sea surface 14c difference was roughly 700 800 yr during the yd whereas today it is 400 500 yr a reduced advection of surface waters to the north atlantic and the presence of sea ice are identified as potential causes of the high 14c reservoir age during the yd

delineation of shallow subsurface structure by azimuthal resistivity sounding and joint inversion of ves tem data case study near lake qaroun el fayoum egypt an azimuthal resistivity survey was conducted at the transition zone between the desert area and the cultivated land near lake qaroun egypt this area has been affected by an east west trending fault system as indicated from the surface geology apparent resistivity values were plotted along azimuth on a polar diagram resistivity anomalies for most of the ab 2 values with long axes strike in a direction parallel to the contact between the desert and cultivated lands indicate the presence of electrical macro anisotropy mainly due to the faulting effect at this area vertical electrical soundings ves and transient electromagnetic tem measurements were conducted at eight stations along a line that crosses the boundary between the desert and cultivated land joint inversion of ves tem data was successfully used for identification of the subsurface lithostratigraphic succession and demonstrated the effect of the fault zone on the investigated subsurface medium apparent anisotropy coefficients at all current electrode spacings were calculated plotted against ab 2 values and compared with the geoelectrical cross section the effect of the fault zone was detected at ab 2 spacings equal to 100 m and extended downward and is largely related to the depth of the fault as indicated in the constructed cross section

examples of resolution improvement in geoelectrical soundings applied to groundwater investigations1 one simulation and two field examples from new jersey illustrate resolution improvement in geoelectrical soundings applied to groundwater exploration layered earth parameter resolution is derived from data obtained with the commonly used methods of resistivity induced polarization ip and transient electromagnetic tem soundings resolution improvement is achieved by simultaneous inversion of two or more data sets and by constraining parameters of the inverse problem a quantitative analysis showing the contribution of ip data to the resolution of geo electric sections is presented simultaneous inversion of simple ip data with conventional resistivity and resistivity tem data sets resulted in improved parameter resolution ip data improved resolution in three ways 1 by decoupling correlated layered earth parameters 2 by adding information to a geological interpretation about a second physical property namely chargeability and 3 by increasing the electrical information available

fracture mapping in the soultz sous forets geothermal field using microearthquake locations 1 in 2003 a massive hydraulic fracturing experiment was carried out at the european geothermal hot dry rock site at soultz sous forets france the 2 week injection of water generated a high level of microseismic activity triggering about 90 000 microearthquakes during and after the fluid injection of these 21 000 events detected at all stations were located individually with a grid search algorithm to characterize the extent of the seismic zones and ultimately of the fracture network the accuracy of these initial locations was around 70 m not sufficient to map detailed fracture patterns a precise relocation effort was undertaken to reduce the location uncertainties using three different techniques joint hypocenter determination jhd collapsing and multiplet analysis the collapsing method was added to the jhd results to further consolidate the hypocenters on the other hand a multiplet analysis was performed on the initial data set for identifying microearthquakes with similar waveforms and hence relocating relatively the correlated events the delays in traveltime were computed by wavelet analysis and the events were relocated using a grid search algorithm we found 7463 events whose seismograms correlated with a correlation coefficient of 0 8 or higher most of which were doublets multiplets are horizontal tube like structures with lengths from a hundred to several hundred meters striking along the direction of the maximum compressive horizontal stress we interpret these structures as the preferential paths where fluid flow is largely confined this hypothesis is reinforced by the good correlation in depth between the events and the fluid outflows observed in the well therefore we believe that these relocated events highlight the zones where the permeability of the reservoir is increased

barriers barrier platforms and spillover deposits in st george s bay newfoundland paraglacial sedimentation on the flanks of a deep coastal basin abstract st george s bay and adjacent coastal areas of southwest newfoundland contain thick sequences of late quaternary glaciogenic sediments and have been subject to relative sea level fluctuations over a rang of 70 m during the past 13 5 ka glaciogenic sediments have been mobilized by littoral processes to form two types of deposits these are 1 the prograded barrier beach and spit at stephenville and flat island respectively which are associated with large subaqueous sandy platforms and 2 a wedge of well stratified sand and gravel on the landward flank of the shallow sill which extends across st george s bay at an average depth of about 25 m the subaerial barriers and spits are composed of gravel beach ridges overlain locally by thin aeolian deposits with freshwater and salt marsh peats in swales these barriers developed during the last several thousand years as relative sea level approached its present position from an early postglacial minimum of approximately 25 m the prerequisite for beach ridge formation was the deposition of large sandy subaqueous platforms which appear on shallow seismic reflection records as clinoform wedges prograded into the deep basin of inner st george s bay the barrier platform at stephenville is constructed across a deep submarine valley the flat island barrier platform sits on the flank of a glacially overdeepened trough partly filled by glacial and postglacial sediments and envelops a delta formed during the early postglacial low stand of relative sea level the platform and barrier together constitute a thick coastal sequence coarsening up from sandy mud at the base to gravel at the top the wedge of well stratified coarse sediment up to 50 m thick situated on the landward flank of the shallow sill overlies older glaciogenic sediments and passes laterally into postglacial basin muds steep foreset reflections dipping 10 20 are evident on shallow seismic reflection records suggesting that the wedge was formed by spillover of sediment entrained by wave and current action into the relatively deep basins of the inner bay active gravel ripples testify to the continued mobility of coarse sediment on the sill the formation of the spillover deposits barriers and platforms demonstrates the potential for glacially overdeepened basins to host thick heterogeneous coarse grained coastal and inner shelf deposits

detection and characterization of seismic phases using continuous spectral estimation on incoherent and partially coherent arrays summary seismic arrays are employed in the global monitoring of earthquakes and explosions because of their superior ability to detect and estimate the direction of incident seismic arrivals traditional beamforming and f k analysis require waveform semblance over the full array aperture and cannot be applied in many situations where signals are incoherent between sensors the norsar and mjar arrays are two primary ims stations where this is the case for high frequency regional phases large intersite distances and significant geological heterogeneity at these arrays result in waveform dissimilarity which precludes coherent array processing in the frequency bands with optimal snr multitaper methods provide low variance spectral estimates over short time windows and seismic arrivals can be detected on single channels using a non linear spectrogram transformation which attains local maxima at times and frequencies characterized by an energy increase this detection procedure requires very little a priori knowledge of the spectral content of the signal the transformed spectrograms can be beamformed over large aperture arrays or networks according to theoretical time delays resulting in an incoherent detection system which does not require waveform semblance at any frequencies we outline a real time automatic detection system for regional phase arrivals on the norsar array and demonstrate how stable and accurate slowness and azimuth estimates can be obtained for quite marginal signals in the case of partially coherent arrays the procedure described may provide stable if low resolution estimates which can subsequently be refined using coherent processing over subsets of sensors in particular we illustrate how the spectrogram beamforming method facilitates a stable and accurate slowness estimate for the incoherent high frequency pn arrival at the mjar array in japan from the 2006 october 9 underground nuclear test in north korea

late holocene sea level change around newfoundland differential sea level change in formerly glaciated areas is predicted owing to variability in extent and timing of glacial coverage newfoundland is situated close to the margin of the former laurentide ice sheet and the orientation of the shoreline affords the opportunity to investigate variable rates and magnitudes of sea level change analysis of salt marsh records at four sites around the island yields late holocene sea level trends these trends indicate differential sea level change in recent millennia a north south geographic trend reflects submergence in the south very slow sea level rise in the northeast and a recent transition from falling to rising sea level at the base of the northern peninsula this variability is best explained as a continued isostatic response to deglaciation

sediment accumulation in low sedimentation wave dominated glaciated inlets abstract many fjords situated in lowland areas of resistant bedrock are characterized by a comparatively low fluvial sediment flux and are often dominated by wave processes several such fjords in eastern canada are used as examples to develop a generalized sediment distribution model physiographically the fjords can be subdivided into nearshore platforms basin slopes and basin floors where there has been marine transgression the principal sediment source is shoreline erosion of glacial till in areas of crustal rebound late glacial and early holocene muds deposited on highs are eroded as they come within the zone of wave erosion with the falling sea level storm waves resuspend fine grained sediment in water depths of many tens of metres and produce near bottom turbid water zones within basins fine sand and silt settle out rapidly leading to the deposition of graded beds on the basin floors residual sand and gravel accumulate on the near shore platforms while silt and mud prograde over or are advected beyond basin slopes burying older basin fill sediment

mapping groundwater salinization using transient electromagnetic and direct current resistivity methods in azraq basin jordan abstracthydrogeophysical characterization using the transient electromagnetic method tem and the dc resistivity sounding ves method was implemented in the central part of azraq basin qa basin jordan to identify and map the spatial distribution of shallow fresh and saline groundwater in the upper aquifer systems the alluvium al and chert limestone urc shallow aquifers show different degrees of groundwater salinization the range of groundwater resistivity varies from 0 06 to 10 8 ohm m saline groundwater was detected at depths between 5 to 30 m where the aquifers have a wide spectrum of resistivity values from 0 14 to 120 ohm m the integrated geophysical and hydrogeologic models are significantly correlated in chloride concentration groundwater resistivity and aquifer resistivity using 1d inversion results from the tem and ves soundings in addition to quasi 3d modeling 1d spatially constrained inversion at selected tem sites groundwater resistivity variation was attributed to two diffe

forms response times and variability of relative sea level curves glaciated north america abstract relative sea level curves from glaciated north america reveal coherent spatial patterns of response times in the laurentide ice sheet area curve half lives range from 1 2 1 4 ka at the uplift centre to 1 7 2 ka in a ridge of high values inboard of the glacial limit half lives decline from this ridge to less than 1 ka along the margin in the innuitian ice sheet area half lives are about 2 ka at the uplift centre and decline to less than 1 ka at the margin the central laurentide response times are about half those of central fennoscandia this accords with the theoretical expectation that central response times are inversely proportional to ice sheet radius for ice loads large enough that rebound at the centre is insensitive to lithospheric thickness the innuitian central response time indicates that rebound at the centre of this ice sheet which is much smaller than the fennoscandian ice sheet remains sensitive to lithospheric thickness radial gradients in response times reflect the increasing influence of the lithosphere at sites increasingly closer to the margin along this gradient rebound progresses as though at the centres of smaller and smaller ice sheets that is the effective spatial scale of the ice load decreases toward the margin near the glacial limit postglacial isostatic adjustment is complicated by forebulge migration and collapse this is seen most strongly in the relative sea level record of atlantic canada which has subsided during the holocene more than 20 m more than the adjacent american seaboard the relative sea level history of some areas notably the st lawrence estuary is complicated by tectonic processes

a new sea level curve from nova scotia evidence for a rapid acceleration of sea level rise in the late mid holocene a new late holocene sea level curve is presented from the atlantic coast of nova scotia contrary to earlier data from the same area this curve starts at 4400 sidereal years before present bp and shows a rapid acceleration between 4400 and 3800 bp which coincides with a similar acceleration already reported from the northumberland strait nova scotia and an oscillation observed in south carolina comparing the two nova scotia curves suggests that the acceleration lasts just over 1000 years and has a vertical extent of 10 m one puzzling fact is that the 10 m vertical extent in nova scotia is 8 m more than the same event measured in south carolina and it cannot be accounted for simply by postglacial isostatic depression since that occurs on a much longer time scale a closer examination of most of the sea level curves from northeastern north america reveals that either the record is missing from this interval or it is inconsistent we suggest that this acceleration is part of a global response that c

evolution d un milieu littoral et remontee du niveau relatif de la mer a l holocene superieur au nord de l ile du cap breton nouvelle ecosse the sedimentary sequence in a coastal pond on cape breton island was examined by various analyses pollen plant macrofossils diatoms and rhizopods the results allow for the reconstruction of different phases in the evolution of the pond in conjunction with relative sea level rise during the late holocene throughout the period studied the microflora and microfauna indicate that the pond was mainly freshwater isolated from the sea by a continuous sand and gravel bar three phases in the pond evolution have been identified 1 the lowermost part of the sequence is characterized by mineral detrital deposits and some marine fossils related to the reworking of bar sediment by storms and high tides washing over the rock sill 2 this was followed by a rapid filling of the basin by organic detritus provided by shore washing processes 3 a marsh evolving into a shallow lake completes the sequence up to the interruption by human occupation the lake level rise is linked to the formation of the bar which

using foraminiferal transfer functions to produce high resolution sea level records from salt marsh deposits maine usa quantitative analyses of foraminiferal distributions along the coast of maine are used to provide transfer functions for reconstruction of sea level changes from fossil foraminiferal assemblages the indicative meaning of fossil assemblages is most accurately predicted by a training set that incorporates live and dead foraminifera and that uses flooding duration not height as the predictor variable sea level records are produced for two sites in maine usa a middle marsh site in scarboro and a high marsh site in machiasport these records offer temporal resolution of five to seven years and span the past century they are compared with instrumental data from a nearby tidal station to assess their accuracy strong correlations are found between the geologic records and the observational data in particular between the foraminiferal record from machiasport and the tide gauge record from eastport r2 0 83 p 0 005 thus a foraminifera based transfer function approach offers great potential for reso