episodic post rift subsidence of the united states atlantic continental margin sediment thickness paleobathymetry and chronostratigraphy from cost wells offshore from georgia and new jersey indicate periods of rapid subsidence superimposed on the slower thermal subsidence of the continental margin rapid subsidence occurred during the coniacian santonian the eocene and in the cost wells off new jersey since the end of early miocene once the maximum effects of water and sediment loading compaction and thermal cooling are removed the residual vertical movements caused by tectonic and sea level fluctuations can be analyzed because no global sea level change can account for all residual movements we propose that tectonism variously amplified by loading is responsible for the observed episodes of rapid subsidence synchroneity of subsidence with sea floor spreading changes in the north atlantic suggests a unified cause for these events recognition of episodic subsidence may have implications for fault timing petroleum potential and global sea level effects on passive margins

recovery of small strain stiffness following blast induced liquefaction based on shear wave velocity measurements changes in soil fabric following liquefaction have been studied using various in situ methods and often return inconclusive or conflicting observations the time rate variation of stiffness when

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

recognition of non milankovitch sea level highstands at 185 and 343 thousand years ago from u th dating of bahamas sediment abstract thirty one new bulk sediment u th dates are presented together with an improved 18o stratigraphy for odp site 1008a on the slopes of the bahamas banks these ages supplement and extend those from previous studies and provide constraints on the timing of sea level highstands associated with marine isotope stages mis 7 and 9 ages are screened for reliability based on their initial u and th isotope ratios and on the aragonite fraction of the sediment twelve reliable dates for mis 7 suggest that its start is concordant with that predicted if climate is forced by northern hemisphere summer insolation following the theory of milankovitch but u th and 18o data indicate the presence of an additional highstand which post dates the expected end of mis 7 by up to 10 ka this event is also seen in coral reconstructions of sea level it suggests that sea level is not responding in any simple way to northern hemisphere summer insolation and that tuned chronologies which make such an assumption are in error by 10 ka at this time u th dates for mis 9 also suggest a potential mismatch between the actual timing of sea level and that predicted by simple mid latitude northern hemisphere forcing four dates are earlier than that predicted for the start of mis 9 although the most extreme of these dates may not be reliable based on the low aragonite content of the sediment the other three appear robust and suggest that full mis 9 interglacial conditions were established at 343 ka this is 8 ka prior to the date expected if this warm period were driven by northern hemisphere summer insolation

multi level slug tests in highly permeable formations 1 modification of the springer gelhar sg model a multi level slug test model and a method for the evaluation of vertical profiles of hydraulic conductivity in highly permeable formations are developed a double packer system is employed to estimate local hydraulic conductivity depending on the formation and double packer system parameters the water level recovery in the tested well can exhibit a monotonic or oscillatory response to discern information on aquifer properties from artifacts introduced by the measurement system the theory of flow in an aquifer and a double packer system is developed the mathematical model incorporates features of the springer and gelhar 1991 model and reduces to the bouwer and rice 1976 model in a special case the model involves equations of momentum and mass conservation for the double packer system with quasi steady well aquifer interaction equations the method is uniformly applicable for both monotonic and oscillatory well responses and can produce profiles of hydraulic conductivity for the tested well the criterion is given to determine the type of well response for given slug test conditions

direct simulation of random field samples from sparsely measured geotechnical data with consideration of uncertainty in interpretation random field theory has been increasingly used in probabilistic geotechnical analyses over the past few decades where a random field generator with random field parameters is needed to simulate random field samples rfss of interest estimation of random field parameters particularly correlation functions or correlation length generally requires extensive measurements however the data gathered from site characterizations are usually sparse particularly for small or medium sized projects therefore it is difficult to provide an accurate estimation on random field parameters and the random field parameters estimated and subsequently used in rfs generation might contain significant uncertainty this leads to a challenge of properly simulating rfss in consideration of such uncertainty this paper aims to address this challenge by developing a novel random field generator which is capable of directly generating rfss from sparse measurements obtained during site characterization and properly accountin

assessment of mineralogical and petrographic factors affecting petro physical properties strength and cracking processes of volcanic rocks abstract microtextural features influence the petrophysical and mechanical properties of rocks including the elastic properties and cracking processes under axial loads volcanic rocks with varying microtextural characteristics and compositions were evaluated to assess the effect of the main constituents mineralogical petrographic and micro structural features on the petrophysical properties elastic properties and strength furthermore detailed analyses were also used to understand the cracking processes under axial loads the analyses of the cracking processes were completed on thin sections obtained from the mechanically tested specimens the results from the quantitative mineralogical and petrographic studies and observations from thin sections revealed that the mineral mass fractions have an effect on the specific gravity and loss on ignition loi values on the other hand unconfined compressive strength ucs and elastic properties are mostly affected by petrographic variables e g mineral content the ucs values tend to decrease with a relative increase in the groundmass with respect to the phenocryst content and vice versa biotite is the only mineral that influences the ucs individually geometric features e g feret s diameter and perimeter of opaque minerals and biotite are determined to be important constituents influencing the young s modulus under axial loads crack propagation is strongly dependent on the proportional distribution of the phenocryst and groundmass it was observed that increasing groundmass content leads to predominantly axial cracks the cracks tend to bend or propagate as a boundary crack when they reach the boundary of an unaltered phenocryst thus axial and shear cracks co exist with increasing amounts of phenocrysts which hinders crack propagation occasionally cracks can penetrate the altered or opaque phenocrysts depending on the degrees of orientation with respect to applied load of the same minerals furthermore the synthesis of the measurements obtained from ucs tests and thin section observations reveals that an increase in the amount of phenocrysts which promote the formation of more shear cracks in addition to axial cracks causes an increase in the radial strain and poisson s ratio the other factors investigated had minor effects on physical and mechanical properties of studied rocks

effects of silt content and void ratio on the saturated hydraulic conductivity and compressibility of sand silt mixtures the hydraulic conductivity the coefficient of consolidation and the coefficient of volume compressibility play major roles on the pore pressure generation during undrained and partially drained loading of granular soils with fines this paper aims to determine how much these soil parameters are affected by the percentage of fines and void ratio of the soil the results of a large number of flexible wall permeameter tests performed on 60 specimens of two poorly graded sands with 0 5 10 15 20 and 25 nonplastic silt are presented and discussed hydraulic conductivity measurements were done at effective confining stresses of 50 300 kpa the evaluation of the data shows that the hydraulic conductivity and the coefficient of consolidation of sands with 25 silt content are approximately two orders of magnitude smaller than those of clean sands the coefficient of volume compressibility of the sand silt mixtures is affected in a lesser degree by void ratio silt content and confining stress the influence of the degree of saturation on the laboratory measured k values is also discussed

analysis of slug tests in bypassed wells in berlin many wells are constructed with an additional small diameter bypass tube flanged on to the large diameter casing and running parallel to the later upward to the surface the response to a slug test conducted in such a well is usually characterised by significant water level oscillations developing inside the branched pipe system in the present paper a general non linear model is developed for the analysis of slug tests performed in bypassed wells the model includes skin effects non linear head losses due to internal well bore fluid friction minor losses originating at radius changes along the flow path inside the well and inertial effects of the water columns contained within the primary casing and the bypass pipe flow inside the branched tubing system is described by the one dimensional conservation law of the mechanical energy of the well bore fluid aquifer flow is quantified by a convolution type approach the coupled well aquifer system is governed by an integro differential equation representing the mean mechanical energy of the total well bore fluid and coupled to it by a non linear ordinary differential equation which accounts for mechanical energy fluctuations between the water columns inside the main casing and the bypass both equations are solved by finite difference approximations coupled to point iterative numerical techniques an application of the model to field data suggests that non linear hydraulic head losses originating inside the well bore may cause the measured head responses to depend on the initial displacement a packer used to initiate a slug test can induce these non linear distortions through the combined effect of minor losses originating at the inlet and the outlet of a small diameter packer flow through tube and internal fluid friction potentially developing inside that packer passage as classical linear theories do not allow for the analysis of such phenomena a model accounting for these non linear processes should be used if field data show significant dependencies on the initial slug height

controls of grain size distribution on geomechanical properties of reservoir rock a case study cretaceous khafji member zuluf field offshore arabian gulf abstract the khafji member of the cretaceous wasia formation in zuluf field offshore saudi arabia is an important siliciclastic hydrocarbon reservoir the reservoir consists of a lower main sand and an upper stringer sand the present study investigated the relationships between the geomechanical attributes young s modulus and poisson s ratio of the reservoir and its grain size distribution in addition an attempt was also made to relate the reservoir quality with the depositional environments deduced from factor analysis of the grain size distribution data the young s modulus for the khafji reservoir range from a low of 8 43 105 psi at 1000 psi confining pressure 1 13 106 psi at 2900 psi confining pressure to a high of 1 27 106 psi at 1000 psi 1 91 106 psi at 2900 psi the study shows that there is no significant relationship between grain size parameters mean median skewness and kurtosis and geomechanical properties however a good correlation was observed between geomechanical parameters and sands deposited in different environments the clean sand showing moderate to good sorting and interpreted as beach sand showed low young s modulus average 1 07 106 psi and poisson s ratio average 0 16 while the parameters were higher average of 1 57 106 psi young s modulus and 0 204 poisson s ratio for the fine grained sediments representing possible lagoonal or offshore environment

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

prediction of engineering properties of a selected litharenite sandstone from its petrographic characteristics using correlation and multivariate statistical techniques abstract the determination of rock strength and elastic parameters in laboratory tests requires high quality core samples which are not always available from fractured and or weathered strata the purpose of this study is to apply a correlation analysis in conjunction with multivariate statistical techniques to petrographical and laboratory geomechanical data for the investigation of correlations that exist between these properties of a selected sandstone and to suggest inexpensive predictive models in a preliminary investigation sandstone samples from a borehole drilled for a preliminary investigation of a shaft location at a hard coal region black sea turkey were tested to determine uniaxial compressive strength elastic parameters unit weight porosity point load index and quality index secondly fifteen selected samples were subjected to petrographic examination which included fifteen parameters and modal analysis based on the statistical analysis results polynomial prediction equations were developed for estimating mechanical properties from petrographic characteristics and index properties the study revealed that the influence of textural characteristics appear to be more important than mineralogy for predicting engineering properties it is also noted that type of contacts grain shape and size rock fragments with packing density and proximity are the petrographic characteristics which have significant influence upon engineering properties of the sandstones results of this study were presented in the form of correlation coefficient models and predictive models

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

cenozoic subsidence and uplift of continents from time varying dynamic topography time varying global dynamic topography has been computed for the entire cenozoic the spherical viscous flow model is driven by a distribution of density heterogeneity based on mesozoic and cenozoic subduction by using the calculated topography the uplift and subsidence histories of five regions fixed to the north american indian australian indonesian and south american continents are computed predicted vertical motions are in qualitative agreement with observed values except for india and south america for australia and north america the predicted periods of uplift and subsidence are out of phase with respect to observations but display the correct overall trend the latest phase of uplift for north america is directly related to the cessation of kula plate subduction after 48 ma dynamic topography depends on the viscosity structure of the mantle a lower mantle that is 50 times more viscous than the upper mantle yields the best agreement between modeled and predicted vertical motions the presence of a low viscosity channel beneath the lithosphere has only a small influence on our results compared to dynamic topography the time varying geoid is insignificant in controlling relative sea level

global glacial isostatic adjustment palaeogeodetic and space geodetic tests of the ice 4g vm2 model analyses of the global process of glacial isostatic adjustment and post glacial relative sea level change continue to deliver important insights into earth system form and process one successful model of the related phenomenology is based upon a spherically symmetric internal viscoelastic structure for the solid earth which has been denoted vm2 and a model of the most recent deglaciation event of the current ice age denoted ice 4g the primary purpose of this paper is to describe several new a posteriori tests that have recently been performed to further investigate the quality of this global solution to the inverse problem for both mantle viscosity and deglaciation history that is posed by the observables associated with this large scale geodynamic phenomenon i focus especially upon the misfits of observations to the theoretical predictions of this model which i am currently using to further refine its properties and upon predictions made using it of geophysical signals that should soon become visible in the context of the gravity recovery and climate experiment grace satellite mission among the required refinements to ice 4g one that is necessary to eliminate a recently revealed misfit to space geodetic constraints on the present day rate of radial motion at the yellowknife location well to the west of hudson bay and a similar misfit to absolute gravity measurements to the southwest of the bay is the insertion of a keewatin dome of thick ice centred over yellowknife with a ridge of ice extending to the south east in the geomorphological literature the existence of such a keewatin dome previously has been hypothesised but chronological control was lacking on the surface features that suggested its former existence an important additional constraint that requires the late glacial existence of this important feature consists of new inferences of the last glacial maximum lowstand of the sea from sites in the far field of the main concentrations of land ice copyright 2002 john wiley sons ltd

relationships between the petrographic physical and mechanical characteristics of sedimentary rocks in jurassic weakly cemented strata physical and petrographic properties of sedimentary rocks have great influence on their mechanical behavior numerous laboratory tests were conducted on intact sandstones and mudstones obtained from jurassic weakly cemented coal bearing strata several physical and mechanical parameters particularly the rock material constant mi and the brittleness coefficient brit t were determined the microfabric of these sedimentary rocks was also analyzed to quantify their mineral compositions and to determine quantitative relationships among mineral compositions physical and mechanical parameters using the regression analysis overall both bulk density and p wave velocity vp exhibit positive power relationships with uniaxial compressive strength ucs and young s modulus e respectively the ucs of sandstones increases with increasing quartz content and decreasing feldspar content and the brittleness of mudstones increases with the increase of quartz and feldspar contents in addition the rock material constant mi presents a logarithmic correlation with the ratio of feldspar to quartz content for sandstones and a polynomial correlation with the ratio of clay minerals to the quartz and feldspar contents for mudstones

generic transformation models for some intact rock properties a global intact rock database of nine parameters including uniaxial compressive strength and young s modulus is compiled from 184 studies this database labeled as rock 9 4069 consists of 27

a linear theory of slug tests with annular effects summary we derive a closed form theory of water level fluctuations caused by slug tests in a well with an annulus that extends to the piezometric surface this hydraulics can be created by small diameter slug test equipment in a large diameter well with an annulus established by borehole casing and the riser pipe of the equipment the conservation of mass equation couples aquifer hydraulics core hydraulics inside the riser pipe which include inertia and annular hydraulics outside the riser pipe which include inertia and linear friction the linear friction is needed to attenuate oscillations between the core and annulus which would otherwise persist indefinitely after damping of aquifer discharge a characteristic velocity is adopted for the annular friction so that aquifer permeability is the sole calibration parameter we calibrate the theory with overdamped and underdamped experiments run in a limestone aquifer at the hydrogeological experimental site of poitiers in france by audouin o bodin j 2007 analysis of slug tests with high frequency oscillations journal of hydrology 334 282 289 the data and analytical theory yield plausible accurate permeability estimates of 4 1 10 12 and 1 7 10 11 m 2 portable small diameter slug testing devices may accordingly be used in permanent large diameter cased boreholes to estimate aquifer permeability although the annular effects can obscure aquifer hydraulics the annular effects may also occur in slug tests on wells with skins bypasses and packers although different boundary and matching conditions would be needed to model this hydraulics

inference of mantle viscosity from grace and relative sea level data summary gravity recovery and climate experiment grace satellite observations of secular changes in gravity near hudson bay and geological measurements of relative sea level rsl changes over the last 10 000 yr in the same region are used in a monte carlo inversion to infer mantle viscosity structure the grace secular change in gravity shows a significant positive anomaly over a broad region 3000 km near hudson bay with a maximum of 2 5 gal yr 1 slightly west of hudson bay the pattern of this anomaly is remarkably consistent with that predicted for postglacial rebound using the ice 5g deglaciation history strongly suggesting a postglacial rebound origin for the gravity change we find that the grace and rsl data are insensitive to mantle viscosity below 1800 km depth a conclusion similar to that from previous studies that used only rsl data for a mantle with homogeneous viscosity the grace and rsl data require a viscosity between 1 4 1021 and 2 3 1021 pa s an inversion for two mantle viscosity layers separated at a depth of 670 km shows an ensemble of viscosity structures compatible with the data while the lowest misfit occurs for upper and lower mantle viscosities of 5 3 1020 and 2 3 1021 pa s respectively a weaker upper mantle may be compensated by a stronger lower mantle such that there exist other models that also provide a reasonable fit to the data we find that the grace and rsl data used in this study cannot resolve more than two layers in the upper 1800 km of the mantle

a 20 m middle pleistocene sea level highstand bermuda and the bahamas due to partial collapse of antarctic ice marine deposits at 20 3 m on the tectonically stable coastlines of bermuda and the bahamas support the hypothesis of a partial collapse of the antarctic ice sheet during the middle pleistocene beach sediments fill a sea cave at 22 m in bermuda and horizontal fenestrae filled beds crop out on platforms at two sites as high as 21 m in eleuthera bahamas carbonate beach sands are bound by an early generation of isopachous fibrous cement that is characteristic of a phreatic marine environment amino acid racemization and tims thermal ionization mass spectrometry dates constrain the age of the deposits to between 390 and 550 ka while proxy evidence supports a correlation with oxygen isotope stage 11 this direct geologic evidence of a 20 decrease in polar ice during the middle pleistocene has important implications for the stability of ice sheets during warm interglaciations

multi level slug tests in highly permeable formations 2 hydraulic conductivity identification method verification and field applications abstract using the developed theory and modified springer gelhar sg model an identification method is proposed for estimating hydraulic conductivity from multi level slug tests the computerized algorithm calculates hydraulic conductivity from both monotonic and oscillatory well responses obtained using a double packer system field verification of the method was performed at a specially designed fully penetrating well of 0 1 m diameter with a 10 m screen in a sand and gravel alluvial aquifer msea site shelton nebraska during well installation disturbed core samples were collected every 0 6 m using a split spoon sampler vertical profiles of hydraulic conductivity were produced on the basis of grain size analysis of the disturbed core samples these results closely correlate with the vertical profile of horizontal hydraulic conductivity obtained by interpreting multi level slug test responses using the modified sg model the identification method was applied to interpret the response from 474 slug tests in 156 locations at the msea site more than 60 of responses were oscillatory the method produced a good match to experimental data for both oscillatory and monotonic responses using an automated curve matching procedure the proposed method allowed us to drastically increase the efficiency of each well used for aquifer characterization and to process massive arrays of field data recommendations generalizing this experience to massive application of the proposed method are developed

structural and tectonic setting of the charleston south carolina region evidence from the tertiary stratigraphic record eleven upper eocene through pliocene stratigraphic units occur in the subsurface of the region surrounding charleston south carolina these units contain a wealth of information concerning the long term tectonic and structural setting of that area these stratigraphic units have a mosaic pattern of distribution rather than a simple layered pattern because deposition erosion and tectonic warping have interacted in a complex manner through time by generating separate structure contour maps for the base of each stratigraphic unit an estimate of the original basal surface of each unit can be reconstructed over wide areas changes in sea level over geologic time generate patterns of deposition and erosion that are geographically unique for the time of each transgression such patterns fail to persist when compared sequentially over time in some areas however there has been persistent repetitive net downward or upward movement over the past 34 m y these repetitive patterns of persistent motion are most readily attributable to tectonism the spatial pattern of these high and low areas is complex but it appears to correlate well with known tectonic features of the region this correlation suggests that the tectonic setting of the charleston region is controlled by scissors like compression on a crustal block located between the north trending adams run fault and the northwest trending charleston fault tectonism is localized in the charleston region because it lies within a discrete hinge zone that accommodates structural movement between the cape fear arch and the southeast georgia embayment

spatial variation in liquefaction risk basic concepts and methods of random field theory useful for characterizing distributed disordered systems are applied to a soil deposit to evaluate the spatial extent of liquefaction under typical conditions the soil deposit modelled after a site located at the wildlife management area in california is represented by a three dimensional random properties field and is subjected to multiple realizations of a space time random field of earthquake ground motion patterned after the superstition hills event of 1987 based on monte carlo analysis using a deterministic one dimensional nonlinear finite element program spatial variability of liquefaction risk is assessed and techniques for improving estimates of liquefaction risk accounting for local spatial variation are investigated les concepts et m6thodes de base de la theorie de champ aleatoire servant caracteogonriser les systemes desordonnes repartis sont appliqueogons un d pot de sol pour evaluer 1 etendue spatiale de la liquefaction dans

mid pliocene shorelines of the us atlantic coastal plain an improved elevation database with comparison to earth model predictions abstract for nearly a century the atlantic coastal plain acp of the united states has been the focus of studies investigating pliocene and pleistocene shorelines however the mapping of paleoshorelines was primarily done by using elevation contours on topographic maps here we review published geologic maps and compare them to paleoshoreline locations obtained through geomorphometric classification and satellite data we furthermore present the results of an extensive field campaign that measured the mid pliocene 3 3 2 9 ma shorelines of the atlantic coastal plain using high accuracy gps and digital elevation models we compare our new dataset to positions and elevations extracted from published maps and find that the extracted site information from earlier studies is prone to significant error both in the location and more severely in the elevation of the paleoshoreline we also investigate using geophysical modeling the origin of post depositional displacement of the shoreline from georgia to virginia in particular we correct the elevation of our shoreline for glacial isostatic adjustment gia and then compare the corrected elevation to predictions of mantle flow induced dynamic topography dt while a subset of these models does reconcile the general trends in the observed elevation of the mid pliocene shoreline local discrepancies persist these discrepancies suggests that either i the dt and gia models presented here do not capture the full range of uncertainty in the input parameters and or ii other influences such as sediment loading and unloading or local fault driven tectonics may have contributed to post depositional deformation of the mid pliocene shoreline that are not captured in the above models in this context our field measurements represent an important observational dataset with which to compare future generations of geodynamic models improvements in models for dt gia and other relevant processes together with an expanded geographically distributed set of shoreline records will ultimately be the key to obtaining more accurate estimates of eustatic sea level not only in the mid pliocene but also earlier in the cenozoic

characterizing the deformation behavior of tertiary sandstones abstract tertiary sandstones possess deformational behavior different from hard rocks especially the relatively larger amount of volumetric dilation during shearing such excess dilation contributes to the increase of crown settlement during tunnel excavation and accounts for several cases of tunnel squeezing within tertiary sandstones therefore the deformation behavior of tertiary sandstones sampled from more than 13 formations was studied to distinguish the volumetric deformation induced by hydrostatic stress or by shear stress as well as to decompose the elastic and the plastic components of strains special experimental techniques including pure shear tests and cycles of loading unloading were applied the experimental results reveal that the deformation of tertiary sandstone exhibits the following characteristics 1 significant amount of shear dilation especially elastic shear dilation 2 non linear elastic and plastic deformation 3 plastic deformation occurs prior to the failure state furthermore features of plastic deformation were inferred from experimental results and as a result the geometry of plastic potential surface and the hardening rule were accordingly determined a constitutive model involving nonlinear elastic plastic deformation and volumetric deformation induced by shear stress is proposed this proposed model simulates the deformational behavior for the shear dilation typed rocks reasonably well furthermore tests on the versatility of the proposed model including varying hydrostatic stress and stress paths indicate that the proposed model is capable of predicting deformational behavior for various conditions

melting ice sheets 400 000 yr ago raised sea level by 13 m past analogue for future trends abstract marine isotope stage mis 11 was possibly the longest 423 000 362 000 yr ago and warmest interglacial of the entire quaternary period this resulted from a special arrangement of earth s orbital parameters similar to the present interglacial mis 1 suggesting that mis 11 provides an analogue for future natural climate forcing and sea levels although precise documentation of mis 11 sea level history is therefore crucial especially considering additional impetus from anthropogenic warming the maximum mis 11 sea level remains highly contentious estimates from onshore indicators have ranged from below present sea level to about 20 m resulting from uncertainties in reliability of sea level indicators estimates of their subsequent displacement by vertical crustal motion and in dating we used a clear and unambiguous sea level indicator interface between subtidal and intertidal deposits in well exposed regressive raised shoreline deposits along south africa s southern coast the coast is stable in terms of tectonic setting and falls within a zone of low predicted glacio isostatic adjustment gia and low sensitivity for plausible model parameters the sea level indicators were directly dated using thermally transferred optically stimulated luminescence tt osl which gave a mean age of 390 ka corresponding with mis 11 we determined a precise maximum elevation of 14 m for the mis 11 sea level indicator which corrected for minor crustal uplift and gia yielded a eustatic sea level of 13 m 2 m the complete mis 11 transgressive regressive shoreline succession is preserved and the wave cut platform extends 950 m inland from the present shoreline indicating a prolonged highstand we have also documented sea level fluctuations during mis 11 including an earlier lower highstand close to present sea level which may explain the lower elevation range of some previous estimates at one locality mis 11 deposits form a sea cliff against which mis 5e sediments at an elevation of 6 2 m abut the 13 m mis 11 sea level tallies with total melting of the greenland and west antarctica ice sheets regarded as most susceptible to melting our data predict notably higher sea levels in the future regardless of anthropogenic influence on climate

the petrographic and geomechanical properties of some sandstones from the newspaper member of the natal group near durban south africa abstract sandstones are by far the most important rock type in the natal group which is mainly a terrestrial succession formed during ordovician silurian times the most notable member of the group is the newspaper member from which sample material was obtained most of the material sampled was fine to medium grained arkosic sandstone they are well cemented with generally low porosity accordingly sandstones of the newspaper member tend to be very strong and of low deformability few of the petrological properties of these sandstones have a notable influence on the mechanical properties however increasing clay content tends to lower the unconfined compressive strength whilst increasing quartz content tends to enhance it on the other hand many of the mechanical properties are interrelated significant or highly significant relationships occur amongst the strength parameters and between hardness and strength young s modulus also has significant relationships with strength and hardness another property which has a significant influence on strength and deformability is porosity

oxygen isotope record of sea level and climate variations in the sulu sea over the past 150 000 years the sulu sea is located in the warm pool of the western pacific ocean where mean annual temperatures are the highest of anywhere on earth because this large heat source supplies the atmosphere with a significant portion of its water vapour and latent heat understanding the climate history of the region is important for reconstructing global palaeoclimate and for predicting future climate change changes in the oxygen isotope composition of planktonic foraminifera from sulu sea sediments have previously been shown to reflect changes in the planetary ice volume at glacial interglacial and millenial timeseales and such records have been obtained for the late pleistocene epoch and the last deglaciation1 3 here i present results that extend the millenial time resolution record back to 150 000 years before present on timescales of around 10 000 years the sulu sea oxygen isotope record matches changes in sea level deduced from coral terraces on the huon peninsula4 this is particularly the case during isotope stage 3 an interglacial period 23 000 to 58 000 years ago where the sulu sea oxygen isotope record deviates from the specmap deep ocean oxygen isotope record5 thus these results support the idea4 6 that there were higher sea levels and less continental ice during stage 3 than the specmap record implies and that sea level during this interglacial was just 40 50 metres below present levels the subsequent rate of increase in continental ice volume during the return to full glacial conditions was correspondingly faster than previously thought

glacioisostatic influences on virginia s late pleistocene coastal plain deposits abstract the late pleistocene of virginia s outer coastal plain consists of sediments dated to marine isotope stages mis 5 and 3 two members from the tabb formation south of the chesapeake bay in southeastern virginia and two formations east of the bay on the southern delmarva peninsula were dated using optically stimulated luminescence osl the stratigraphically older butlers bluff member yielded osl ages of 70 ka 62 78 ka mis 5a and the younger poquoson member and wachapreague formation mis 3 ages of approximately 43 ka 33 50 ka and 42 ka 33 54 ka respectively these shoreface and near shore geologic units reached maximum altitudes ranging from 3 to 12 m above present sea level and were deposited when established glacial eustatic sea level curves suggest that sea levels were significantly lower than present by approximately 40 m if these new ages and the sea level curves are correct there must have been regional uplift of more than 40 m probably due to isostatic adjustments of forebulges peripheral to north american ice sheets when they were at their maxima during mis 6 and mis 2 if the late mis 6 forebulge collapse continued throughout mis 5 and mis 4 we propose that regional land elevations may have been low enough for deposition to occur during the lower eustatic sea levels of mis 3 during late mis 3 the units experienced renewed uplift followed by subsidence to present day elevations if this paraglacial region is not yet in isostatic equilibrium and still requires further forebulge subsidence this could explain the present day altitude and age discrepancies associated with these relict marine deposits

coastal barriers northern gulf last eustatic cycle genetic categories and development contrasts a review abstract a large body of chronologically well constrained and detailed quaternary data accumulated in the last decades from the coastal shelf region of the northern gulf of mexico consequently a preliminary synthesis of major aspects of the late quaternary barrier and mainland coastal development on the northern gulf of mexico is timely several major factors account for the striking differences between barrier size and development styles in the three northern gulf coast regions barriers are nearly continuous in the nw where they dominate by the greatest dimensions and continuity sand supply from shelf and mainland sources continued at variable rates throughout six stages of the last eustatic cycle lec differences in antecedent topography in fluvial runoff volumes and relative sea level rise including rapid overstepping flooding events were critical in the regional distinctions leaving fewer and smaller relict fluvial delta behind drowned shore and nearshore landforms on the shelf only two large fluvial systems impacted the ne the nw shelf and nearshore received abundant sediment supply from the mississippi and lesser streams indirectly by ravinement erosion of relict landforms and landward directed cross shelf sediment transfer sands originated mainly in relict deltas fluvial tidal channel and inlet fill as well as from submerged shore ridge remnants on the continental shelf shelf margin deltas represented major secondary sources barrier formation categories and their respective importance in specific areas represent critical aspects of coastal development the authorship of various formation concepts e g penck gilbert mcgee haage ganong and keilhack often is still miscredited or remains unrecognized in the literature recognition of the stratigraphic and sedimentological diagnostic characteristics of the basic genetic barrier categories plays a key role in testing the validity of barrier evolution models closely knit process form relationships prevail between hydrodynamic sea level change storm tidal current overwash sedimentary shoal and island aggradation rollover and eolian accumulation processes and the resulting landform morphology the most detailed accounts that deal with the development of the alabama louisiana and apalachicola barrier chains are particularly instructive almost all modern gulf barriers with identifiable genetic background formed by shoal aggradation between 5 5 and 2 0 ka during a marked deceleration in sea level rise concurrently a sizable mainland strand plain complex extended the ne coastal plain tide and storm driven sediment transport to the large mobile bay ebb delta the focal role of composite east dauphin island in establishing the ms la island chain and the island blocking role of mississippi delta advance were prime factors in a complex barrier history migration paradoxically may also occur by transgressive rollover concurrently with regressive landward progradation of island strand plains stream discharge and sand reworked from relict lithosomes on the shelf were insufficient in compensating for wave and tide related sediment loss gulf levels stayed below the present throughout the mid and late holocene

textural characterisation of rocks textural characteristics are a major factor in determining the mechanical behaviour of rocks and in the prediction of performance of rock cutting and drilling equipment the principal textural characteristics of rocks are grain size grain shape grain orientation relative proportion of grains and matrix material which were herein quantitatively measured using a modern image analysis system these features resulted in a texture coefficient represented by a single number for each rock specimen in this study a range of both textural and mechanical data for a range of rock types are given with some of the textural determination methodology correlation between textural and physical properties are also highlighted the results of drilling tests using polycrystalline diamond compact pin and hybrid and impregnated diamond core bits in the rocks are presented which demonstrate the influence of rock texture on drillability the rock texture can be used as a predictive factor for assessing the drillability and cuttability mechanical and wear performance of rocks

petrographic quantification of brecciated rocks by image analysis application to the interpretation of elastic wave velocities abstract this paper presents a new procedure to quantify the petrology of materials with complex and heterogenic rock fabric features the classical methodologies for petrographic quantification by image analysis are not appropriate for this kind of rock due to both the high chromatic complexity of these materials and the scale with which the samples are studied the proposed process is particularly interesting for materials with complex chromatic characteristics such as highly fractured rocks concrete etc two commercial varieties of highly fractured brecciated dolostones were selected for this study in order to test the designed methodology this new procedure is based on the analysis process of colour images obtained from mesoscopic sample scanning six petrographic parameters and diagrams have been designed in order to quantify the most influential aspects in compressional v p and shear v s ultrasonic wave propagation these petrographic parameters and diagrams are brecciation density brecciation density map clast size distribution fine grained matrix content shape preferred orientation and rose diagrams the results demonstrate that the proposed methodology is suitable for quantifying the petrography of these kinds of materials furthermore the variations measured in v p and v s are fully explained by the values measured for the following parameters brecciation density fine grained matrix content clast size distribution and preferred orientation of clasts

spatial variability of cpt parameters and silty fines in liquefiable beach sands abstractincreasing awareness of the role of spatial variability in the assessment of liquefaction susceptibility has driven the need to characterize the vertical and horizontal spatial variability

spatially quantitative seafloor habitat mapping example from the northern south carolina inner continental shelf abstract naturally occurring hard bottom areas provide the geological substrate that can support diverse assemblages of sessile benthic organisms which in turn attract many reef dwelling fish species alternatively defining the location and extent of bottom sand bodies is relevant for potential nourishment projects as well as to ensure that transient sediment does not affect reef habitats particularly in sediment starved continental margins furthermore defining sediment transport pathways documents the effects these mobile bedforms have on proximal reef habitats thematic mapping of these substrates is therefore crucial in safeguarding critical habitats and offshore resources of coastal nations this study presents the results of a spatially quantitative mapping approach based on classification of sidescan sonar imagery by using bottom video for image to ground control digital image textural features for pattern recognition and an artificial neural network for rapid quantitative multivariable decision making this approach resulted in recognition rates of hard bottom as high as 87 the recognition of sand bottom was less successful 31 this approach was applied to a large 686 km2 high quality 2 m resolution sidescan sonar mosaic of the northern south carolina inner continental shelf results of this analysis indicate that both surficial sand and hard bottoms of variable extent are present over the study area in total 59 of the imaged area was covered by hard bottom while 41 was covered by sand qualitative spatial correlation between bottom type and bathymetry appears possible from comparison of our interpretive map and available bathymetry hard bottom areas tend to be located on flat low lying areas and sandy bottoms tend to reside on areas of positive relief published bio erosion rates were used to calculate the potential sediment input from the mapped hard bottom areas rendering sediment volumes that may be as high as 0 8 million m3 yr for this portion of the south carolina coast

whole rock aminostratigraphy and quaternary sea level history of the bahamas abstract the surficial geology of the tectonically stable bahamian archipelago preserves one of the most complete records of middle to late quaternary sea level highstand cycles in the world however with the exception of deposits from marine isotope substage mis 5e fossil corals for radiometric dating of this rich stratigraphic sequence are rare this study utilizes the previously published independent lithostratigraphic framework as a testing ground for amino acid racemization in whole rock limestone samples at least six limestone soil couplets provide a relative age sequence of events that encompass as many interglacial glacial cycles d alloisoleucine l isoleucine data fall into six clusters or aminozones on the basis of independent dating and the inferred correlation with global mis the ages of several aminozones are known while the ages of others are calculated from calibrated amino acid geochronology this study demonstrates the utility of the whole rock aminostratigraphy method for dating and correlating widespread emergent marine deposits constitutes the first regional geochronological framework for the bahamas and highlights major sea level events over the past half million years

relationship between textural petrophysical and mechanical properties of quartzites a case study from northwestern himalaya abstract the quantification of various textural parameters and petrophysical mechanical properties of quartzites located in the lesser and higher himalayas has been carried out a dimensionless quantity texture coefficient representing rock texture incorporates various textural parameters like grain shape orientation degree of grain interlocking and relative proportion of grain and matrix packing density has been measured besides shape preferred orientation and grain suturing fractal dimension these have been correlated with the seismic properties like p and s wave velocities and attenuation characteristics and unconfined compressive strength it has been noted that seismic velocity in rocks is a function of various textural parameters like with the increase of aspect ratio grain size and shape preferred orientation velocity increases and with the increase of suturing fractal dimension the velocity decreases the texture coefficient is noted to be inversely proportion to the velocity and there exits strong positive relationships r 0 71 between texture coefficient and the unconfined compressive strength however the relation between the velocity and the unconfined compressive strength is meaningless

relationship between the deformation characteristics and microscopic properties of sandstone explored by the bonded particle model abstract previous research shows that the mechanical properties of sandstone are strongly influenced by porosity and grain area ratio gar this study explores how these microscopic factors affect the elasto plastic deformation of sandstone and adopts a modified bonded particle model to study the deformation behavior of sandstone under biaxial loading compared with the natural sandstone the analysis model can effectively capture the elasto plastic behavior of sandstone including non linear elasticity and the variations of plastic flow furthermore the simulated results of biaxial compressive tests show that the mechanical behavior of sandstone with different porosities and gars possesses the following characteristics the cohesion is significantly influenced by both gar and porosity greater gar and porosity values lead to a lesser cohesion however the influence of gar on the friction angle is insignificant and a lower porosity leads to a higher friction angle for elastic deformation the elastic shear and bulk modulus increase with decreasing porosity and increasing gar for plastic deformation the influence of porosity and gar on the variations of plastic angle under different shear stress ratios seems insignificant on the other hand the plastic strain trajectory increases with increasing porosity but the influence of gar is insignificant

sea level responses to rapid sediment erosion and deposition in taiwan abstract numerous studies have shown that sediment deposition can perturb sea level by several meters over millennial timescales by modifying the gravity field crustal elevation and sediment thickness relatively few studies have focused on the complementary role of erosion on sea level change despite its effects on the same quantities partly because many rapidly eroding mountains are too far from shorelines to strongly perturb sea level at the coast taiwan a mountainous island eroding rapidly within tens of km of the coast offers an opportunity to investigate the joint influences of rapid onshore erosion and rapid offshore deposition on sea level change here we develop a sediment loading history for taiwan since the previous interglacial 120 ka by compiling published erosion and deposition rate measurements and by applying a geometric marine sediment deposition and compaction model for sites without deposition rate measurements we use the resulting sediment redistribution history to drive sea level responses in a gravitationally self consistent sea level model our simulations show that the effects of rapid onshore erosion outweigh the effects of rapid offshore deposition along taiwan s east coast along the east coast of taiwan sediment redistribution induces rapid sea level fall a response that differs in sign from the coastal sea level rise induced by rapid sediment redistribution in many other river systems around the world the spatial extent of the modeled sea level fall is sensitive to the earth model particularly the effective elastic thickness of the lithosphere a sensitivity that we describe in further detail in the discussion these results suggest that sediment redistribution could have generated sea level changes of 10 m on the east coast of taiwan since 10 ka and 100 m since 120 ka this can account for some of the discrepancy between observed and modeled paleo sea level marker elevations which reduces estimates of tectonically driven rock uplift rates inferred from the elevation differences between paleo sea level markers and modeled sea level this highlights the importance of accounting for erosional unloading in interpretations of paleo sea level reconstructions and associated estimates of tectonically driven uplift rates

a synthesis of the geologic evolution of taiwan abstract the island arc of taiwan is composed of cenozoic geosynclinal sediments more than 10 000 m thick lying on a pre tertiary metamorphic basement pleistocene to miocene andesitic islands surround the main island and are related mostly to arc magmatism the penghu island group in the taiwan strait is covered with pleistocene flood basalt neogene shallow marine clastic sediments are exposed mainly in the western foothills with pleistocene andesitic extrusives at the northern tip and the northeastern offshore islands a thick sequence of paleogene to miocene argillitic to slaty metaclastic rocks underlies the western central range and forms the immediate sedimentary cover on the pre tertiary metamorphic complex to the east which represents an older mesozoic arc trench system the coastal range in eastern taiwan is a neogene andesitic magmatic arc including also a large variety of volcaniclastic and turbiditic sediments cenozoic taiwan is the site of arc continent collision where the luzon arc on the philippine sea plate overrides the chinese continental margin on the eurasian plate east and northeast of taiwan the polarity of subduction changes whereby the oceanic philippine sea plate is subducting beneath the ryukyu arc system on the eurasian plate continent arc collision in taiwan island is anomalous and may occur in a broad belt of deformation rather than along a well defined plate boundary or subduction zone

an analysis and comparison of observed pleistocene south carolina usa shoreline elevations with predicted elevations derived from marine oxygen isotope stages geological maps of south carolina covering 6800 km2 confirm the existence of eight preserved pleistocene shorelines above current sea level marietta 42 6 m wicomico 27 4 m penholoway 21 3 m ladson 17 4 m ten mile hill 10 7 m pamlico 6 7 m princess anne 5 2 m and silver bluff 3 m current geochronologic data suggest that these eight shorelines correlate with marine oxygen isotope stages mis as follows marietta older than mis 77 wicomico mis 55 45 penholoway mis 19 or 17 ladson mis 11 ten mile hill mis 7 pamlico mis 5 princess anne mis 5 and silver bluff mis 5 or 3 except for the mis 5e pamlico and possibly the mis 11 ladson the south carolina elevations are higher than predicted by isotope proxy based reconstructions the 4 m of total relief from the pamlico to the silver bluff shoreline in south carolina for which other reconstructions suggest an expected relief of 80 m illustrates the lack of match our results suggest that processes affecting either post depositional changes in shoreline elevations or the creation of proxy sea level estimates must be considered before using paleo sea level position on continental margins

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

analysis of well aquifer response to a slug test the response of a fully penetrating well to a slug test in a confined aquifer can be described by a single differential equation that is valid for any degree of damping although an analytical solution is not available numerical methods are readily applied the impact of nonlinear terms becomes significant only when the initial water level displacement is a large fraction of the effective water column height previously published approximate solutions for underdamped response are sometimes very accurate

late cenozoic flexural deformation of the middle u s atlantic passive margin despite the century long recognition of regional epeirogeny along the middle atlantic passive margin relatively few studies have focused on understanding postrift uplift mechanisms here we demonstrate that epeirogenic uplift of the central appalachian piedmont and subsidence of the salisbury embayment represent first order flexural isostatic processes driven by continental denudation and offshore deposition our results show that regional epeirogenic processes present on all atlantic type passive margins are best resolved by specific stratigraphic and geomorphic relationships rather than topography a simple one dimensional geodynamic model constrained by well dated baltimore canyon trough coastal plain and lower susquehanna river piedmont stratigraphy simulates flexural deformation of the u s atlantic margin the model represents the passive margin lithosphere as a uniformly thick elastic plate without horizontal compressive stresses that deforms flexurally under the stress of strike averaged vertically applied line loads model results illustrate a complex interaction among margin stratigraphy and geomorphology the isostatic response to denudational and depositional processes and the modulating influence of exogenic forces such as eustasy the current elevation with respect to modern sea level of fluvial terraces and correlative coastal plain deposits or unconformities is successfully predicted through the synthesis of paleotopography eustatic change and margin flexure results suggest that the middle u s atlantic margin landward of east coast magnetic anomaly is underlain by lithosphere with an average elastic thickness of 40 km flexural rigidity d 4 1023 n m the margin experiences an average long term denudation rate of approximately 10 m m y and the piedmont has been flexurally upwarped between 35 and 130 meters in the last 15 m y long term isostatic continental uplift resulting from denudation and basin subsidence resulting from sediment loading are accommodated primarily by a convex up flexural hinge physiographically represented by the fall zone our results elucidate an inherent danger in using topography alone to constrain late stage passive margin deformation mechanisms only through careful synthesis of field stratigraphic and geomorphic elements such as fluvial terraces coastal plain deposits and offshore stratigraphy can age control be extended from the offshore depositional setting to the erosionally dominated continent this study demonstrates that despite a relatively subdued topography the middle u s atlantic margin experiences progressive flexural isostatic deformation similar to that proposed for high relief margins characterized by great escarpments thus margin topographic diversity remains a function of other factors such as lithospheric composition and or structure supracrustal stratigraphy and structure degree of drainage integration drainage divide migration and climate

constraining models of postglacial rebound using space geodesy a detailed assessment of model ice 5g vm2 and its relatives summary using global positioning system very long baseline interferometry satellite laser ranging and doppler orbitography and radiopositioning integrated by satellite observations including the canadian base network and fennoscandian bifrost array we constrain in models of postglacial rebound the thickness of the ice sheets as a function of position and time and the viscosity of the mantle as a function of depth we test model ice 5g vm2 t90 rot which well fits many hundred holocene relative sea level histories in north america europe and worldwide ice 5g is the deglaciation history having more ice in western canada than ice 4g vm2 is the mantle viscosity profile having a mean upper mantle viscosity of 0 5 1021 pa s and a mean uppermost lower mantle viscosity of 1 6 1021 pa s t90 is an elastic lithosphere thickness of 90 km and rot designates that the model includes rotational feedback earth s response to the wander of the north pole of earth s spin axis towards canada at a speed of 1 myr 1 the vertical observations in north america show that relative to ice 5g the laurentide ice sheet at last glacial maximum lgm at 26 ka was 1 much thinner in southern manitoba 2 thinner near yellowknife northwest territories 3 thicker in eastern and southern quebec and 4 thicker along the northern british columbia alberta border or that ice was unloaded from these areas later thicker or earlier thinner than in ice 5g the data indicate that the western laurentide ice sheet was intermediate in mass between ice 5g and ice 4g the vertical observations and grace gravity data together suggest that the western laurentide ice sheet was nearly as massive as that in ice 5g but distributed more broadly across northwestern canada vm2 poorly fits the horizontal observations in north america predicting places along the margins of the laurentide ice sheet to be moving laterally away from the ice centre at 2 mm yr 1 in ice 4g and 3 mm yr 1 in ice 5g in disagreement with the observation that the interior of the north american plate is deforming more slowly than 1 mm yr 1 substituting vm5a t60 for vm2 t90 that is introducing into the lithosphere at its base a layer with a high viscosity of 10 1021 pa s greatly improves the fit of the horizontal observations in north america ice 4g vm5a t60 rot predicts most of the north american plate to be moving horizontally more slowly than 1 mm yr 1 in agreement with the data ice 5g vm5a t60 rot well fits both the vertical and horizontal observations in europe the space geodetic data cannot distinguish between models with and without rotational feedback in the vertical because the velocity of earth centre is uncertain and in the horizontal because the areas of the plate interiors having geodetic sites is not large enough to detect the small differences in the predictions of rotational feedback going across the plate interiors

the control of mineral constituents and textural characteristics on the petrophysical mechanical pm properties of different rocks of the himalaya abstract petrophysical and mechanical pm properties of a rock are primarily controlled by its mineral constituents and various textural parameters similar rock types in different tectonic setups may be characterized by different mineralogical compositions and textural properties because they might have suffered different deformational processes this paper presents a study on the mineralogical and textural control on various pm properties in quartzites granitoids gneisses metabasics and dolomite collected from different tectonic set ups the inter relationships among mineral constituents various textural parameters unconfined compressive strength ucs schmidt hammer rebound r value seismic wave both p and s waves velocity and their attenuation characteristics were obtained using regression analyses it has been concluded that there exists no relation between ucs and seismic wave velocity in quartzite granitoids and gneisses moderate positive relationship in metabasics and strong negative relationship in dolomite it has further been noted that in quartzite and dolomite monominerelic rocks grain size dominantly control the seismic wave velocity as the relatively coarser grained samples have higher seismic wave velocity whereas ucs is strongly controlled by grain size as well as the quantity and the orientation of the weak minerals like muscovite biotite calcite etc in gneisses and granitic gneisses preferred orientation of minerals especially the mica minerals although in present small quantity is the main factor controlling ucs and seismic velocity both these properties increase with the increase in intensity of preferred alignment of minerals whereas in metabasics it is the presence of amphibole pyroxene minerals feldspar that dominantly controls the seismic wave velocity

amino acid age estimates quaternary atlantic coastal plain comparison with u series dates biostratigraphy and paleomagnetic control amino acid enantiomeric dl ratios in the mollusk mercenaria are compared with recently published biostratigraphic and or u series solitary coral data from 22 quaternary localities on the central and southern atlantic coastal plain in all cases local relative aminostratigraphic sequences are consistent with relative ages inferred from u series or biostratigraphic data although occasionally more depositional events are recognized by aminostratigraphic than biostratigraphic methods however if the u series data are used as age calibrations for the dl values latitudinal trends of isochronous dl values are highly variable and conflict with trends expected from the present temperature gradient which is smooth and nearly linear between 45 and 25 n age estimation can be performed independently of the u series data using a kinetic model that relies on the assumption that pleistocene temperature gradients have also been smooth functions of latitude although significantly steeper than the present temperature gradient within the uncertainties of this assumption kinetic model age estimates for localities in the coastal plain fall into the following groups 70 000 130 000 yr 200 250 000 yr 300 000 400 000 yr 500 000 600 000 yr 700 000 800 000 yr and 1 000 000 yr major conflicts between these model age estimates are observed for localities near charleston south carolina and in central virginia these conflicts could indicate that the basic temperature assumptions of aminostratigraphy are incorrect and that apparent local aminostratigraphic sequences clusters of different dl values could be due to factors other than age difference alternatively some of the u series dates may be only minimum ages for these localities

a preliminary analysis of failure mechanisms in karst and man made underground caves in southern italy abstract natural and anthropogenic caves may represent a potential hazard for the built environment due to the occurrence of instability within caves that may propagate upward and eventually reach the ground surface inducing the occurrence of sinkholes in particular when caves are at shallow depth the effects at the ground surface may be extremely severe apulia region southern italy hosts many sites where hazard associated with sinkholes is very serious due to presence of both natural karst caves and anthropogenic cavities the latter being mostly represented by underground quarries the pliocene pleistocene calcarenite a typical soft rock was extensively quarried underground by digging long and complex networks of tunnels with time these underground activities have progressively been abandoned and their memory lost so that many apulian towns are nowadays located just above the caves due to urban expansion in the last decades therefore a remarkable risk exists for society which should not be left uninvestigated the present contribution deals with the analysis of the most representative failure mechanisms observed in the field for such underground instability processes and the factors that seem to influence the processes as for example those causing weathering of the rock and the consequent degradation of its physical and mechanical properties aimed at exploring the progression of instability of the cavities numerical analyses have been developed by using both the finite element method for geological settings represented by continuous soft rock mass and the distinct element method for jointed rock mass conditions both the effects of local instability processes occurring underground and the effects of the progressive enlargement of the caves on the overall stability of the rock mass have been investigated along with the consequent failure mechanisms in particular degradation processes of the rock mass as a consequence of wetting and weathering phenomena in the areas surrounding the caves have been simulated the results obtained from the numerical simulations have then been compared with what has been observed during field surveys and a satisfactory agreement between the numerical simulations and the instability processes as detected in situ has been noticed

uranium series coral ages from the us atlantic coastal plain the 80 ka problem revisited abstract uranium series coral ages for emergent units from the passive continental margin us atlantic coastal plain acp suggest sea level above present levels at the end of marine oxygen isotope stage mis 5 contradicting age elevation relations based on marine isotopic or coral reef models of ice equivalent sea level we have reexamined this problem by obtaining high precision 230th 238u and 231pa 235u thermal ionization mass spectrometric ages for recently collected and carefully cleaned acp corals many in situ we recognize samples that show no evidence for diagenesis on the basis of uranium isotopic composition and age concordance combining new and earlier data among those ages close to or within the age range of mis 5 over 85 cluster between 65 and 85 ka bp of the corals that we have analyzed those that show the least evidence for diagenesis on the basis of uranium isotopic composition and age concordance have ages between 80 and 85 ka bp consistent with a mis 5a correlation the units from which these samples have been collected are all emergent and have elevations within 3 5 m of those few units where early stage 5 125 000 ka bp coral ages have been obtained the acp appears to record an unusual history of relative sea level throughout mis 5 a history that is also apparent in the dated coral record for bermuda we speculate that this history is related to the regional near to intermediate field effects of ancestral laurentide ice sheets on last interglacial shorelines of the western north atlantic

wetting weakening of tertiary sandstones microscopic mechanism the micromechanism accounting for wetting weakening of tertiary sandstones was studied it was found that intragranular fracture prevails for all dry sandstones however when the sandstone is wet intergranular fracture occurs for type b sandstones therefore one sandstone from type a sandstones ms1 and another from type b tk were selected to further investigate the nature of the matrix it was found that 1 for both sandstones the major mineral components of the matrix are illite and kaolinite except that the ms1 sandstone has more chlorite 2 leaching of matrix induced an increase of porosity and consequently results in leaching softening and 3 among the mineral composition chlorite is easiest to be dissolved and leached out and induces a more significant increase of porosity which in turn results in a more significant leaching softening

analytical models of slug tests in the present paper attempts are made to develop solutions to various models of slug tests that may be applicable in analyzing the results of such tests where existing solutions are inadequate various geometries that may be encountered in heterogeneous systems such as fractured rocks are considered solutions are presented for linear flow radial flow with boundaries two layer and concentric composite models with different flow geometries between the inner and outer region solutions are obtained in laplace space and inverted back to real space numerically type curves are presented for each solution analyses of the type curves and derivative response curves reveal that many curves have unique shapes only for certain combination of the flow parameters and the distance other sets of type curves are similar in shape although log log plots and derivative plots may emphasize some features that may not be apparent in semilog plots these results show that slug tests suffer problems of nonuniqueness to a greater extent than other well tests

uranium series dating of fossil corals from marine sediments of southeastern united states atlantic coastal plain extensive low lying marine deposits border the southeastern united states atlantic coastal plain some units are fossiliferous and contain corals as isolated fragments in sediments of a detrital character these corals are subject to alteration processes such that suites of related samples must be examined to determine the suitability of these coral samples for reliable uranium series dating with the exception of those from one location most samples appear to have remained closed systems with respect to the isotopes of uranium and thorium throughout their geologic history extraneous 230th has been detected in some of the corals due to incorporation of some detrital materials into their skeletons for these samples different methods are applied to correct for the initial 230th contamination continued sampling and analyses have resulted in 55 individual uranium thorium determinations the average 230th ages of samples from the norfolk formation and from later and earlier deposited sediments of the wando formation are 71 000 87 000 and 129 000 yr and they appear to correlate with oxygen isotope substages 5a 5c and 5e respectively the average 230th age of samples from beds of the rappahannock river ponzer and ten mile hill localities is 212 000 yr and they correlate with oxygen isotope stage 7 the sediment of the canepatch formation is 460 000 yr old and it is tentatively correlated with oxygen isotope stage 11 there is general agreement between uranium series and uranium trend dates and between the quantitative trends of the amino acid data and uranium series dates the amino acid values however ure unacceptably high in at least two groups of samples those from localities near charleston south carolina and from central virginia

quaternary climates and sea levels of the u s atlantic coastal plain uranium series dating of corals from marine deposits of the u s atlantic coastal plain coupled with paleoclimatic reconstructions based on ostracode marine and pollen continent data document at least five relatively warm intervals during the last 500 000 years on the basis of multiple paleoenvironmental criteria we determined relative sea level positions during the warm intervals relative to present mean sea level were 7 5 meters at 188 000 years ago 7 5 1 5 meters at 120 000 years ago 6 5 3 5 meters at 94 000 years ago and 7 3 meters at 72 000 years ago the composite sea level chronology for the atlantic coastal plain is inconsistent with independent estimates of eustatic sea level positions during interglacial intervals of the last 200 000 years hydroisostatic adjustment from glacial interglacial sea level fluctuations lithospheric flexure and isostatic uplift from sediment unloading due to erosion provide possible mechanisms to account for the discrepancies alternatively current eustatic sea level estimates for the middle and late quaternary may require revision

high eustatic sea level during the middle pliocene evidence from the southeastern u s atlantic coastal plain the middle pliocene approximately 3 5 2 5 ma was a period of global warmth preceding the growth of major northern hemisphere ice sheets the authors report on eustatic sea level for the middle pliocene based on microspaleontologic study of marine deposits of the duplin formation of south carolina and north carolina the duplin was deposited during a middle pliocene marine transgression that formed the orangeburg scarp a prominent wave cut geomorphic paleoshoreline of the southeastern u s atlantic coastal plain they concluded that 1 the scarp in south carolina was formed mostly during the middle pliocene 3 5 3 0 ma 2 eustatic sea level was about 35 plus minus 18 m higher than modern sea level the scarp has been uplifted about 50 65 m since the middle pliocene and 3 ocean water temperatures along eastern north america were warmer when the scarp was formed that they are at present

correlation of mineralogical and textural characteristics with engineering properties of selected granitic rocks from turkey abstract granitic rocks show a variety of engineering properties that may affect quarrying operations tunneling mining slope stability and the use of rock as a construction material the physical and mechanical properties are a function of the mineralogical and textural characteristics of the rock the purpose of this study is to apply correlation analysis to investigate the relationships between petrographical and engineering properties of granitic rocks a variety of granitic rock samples from different parts of turkey were subjected to petrographic studies the same samples were then tested to determine specific gravity dry and saturated unit weight water absorption effective and total porosity sonic velocity schmidt hardness point load strength index uniaxial compressive strength tensile strength and modulus of elasticity the relationships between these properties and the petrographical characteristics are described by simple regression analyses the study revealed that the influence of the textural characteristics on the engineering properties appears to be more important than the mineralogy it also determined that the types of contacts grain mineral shape and size significantly influence the engineering properties of the granitic rocks

departures from eustasy in pliocene sea level records estimates for sea level three million years ago a period with similar atmospheric co2 levels to today vary from 10 to 40 m above present glacial isostatic adjustment modelling suggests that variations in the height of palaeoshorelines result from the residual adjustment of continental flexure following recent glaciations

glacial isostatic adjustment and the anomalous tide gauge record of eastern north america sea level variations as recorded by the global network of tide gauges represent a rich data set for studying a wide range of natural and anthropogenic phenomena such as the sea level rise induced by possible global warming for this purpose long term sea level trends must be corrected for the contaminating effects of continuing glacial isostatic adjustment1 5 gia the numerical correction procedure has for sites on the east coast of north america yielded a set of highly anomalous sea level rates characterized by systematic geographical trends2 4 5 we demonstrate that these trends are a consequence of inadequacies in the previous standard numerical prediction for gia in particular we find that the well known trends in the gia corrected tide gauge rates are eliminated if the lower mantle viscosity of the earth model used in the gia prediction is increased this result obviates the need to explain the anomalous trend as a manifestation of gulf stream ocean circulation4 or neotectonic processes2

estimation of subglacial hydraulic properties from induced changes in basal water pressure a theoretical framework for borehole response tests in this paper we develop a theoretical model describing water motion in a coupled borehole subglacial flow system the theory applies to basal drainage systems having multiple and extensive interconnected flow paths within this domain it encompasses a broad range of flow regimes from laminar darcian flow in a thick permeable unit to turbulent sheet flow in a very thin layer important terms in the model are highlighted by recasting the problem in dimensionless form the non dimensional formulation indicates that there are four free parameters in the coupled system these parameters characterize skin friction in the borehole and diffusion transmissivity and turbulent transport in the subglacial flow layer dimensionless results show that under most circumstances the effects of skin friction in the borehole are negligible diffusion transmissivity and especially turbulent transport in the basal layer are found to influence subglacial water flow strongly we use our model to predict fluctuations of borehole water levels that result from different types of disturbances we show how this framework can be used to estimate subglacial hydraulic properties by comparing model results with data collected during field experiments on trapridge glacier yukon territory canada in 1989 and 1990

comparison of amino acid racemization geochronometry with lithostratigraphy biostratigraphy uranium series coral dating and magnetostratigraphy in the atlantic coastal plain of the southeastern united states the results of an integrated study comprising litho and biostratigraphic investigations uranium series coral dating amino acid racemization in molluscs and paleomagnetic measurements are compared to ascertain relative and absolute ages of pleistocene deposits of the atlantic coastal plain in north and south carolina four depositional events are inferred for south carolina and two for north carolina by all methods the data suggest that there are four pleistocene units containing corals that have been dated at about 100 000 yr 200 000 yr 450 000 yr and over 1 000 000 yr some conflicts exist between the different methods regarding the correlation of the younger of these depositional events between charleston and myrtle beach lack of good uranium series dates for the younger material at myrtle beach makes the correlation with the deposits at charleston more difficult

influence of petrographic parameters on geotechnical properties of tertiary sandstones from taiwan while tunneling through tertiary sandstones in taiwan tunnel squeezing occurred in some of the sandstones e g mucha tunnel and chungho tunnel in northern taiwan but not in all of them this phenomenon indicates that the geotechnical properties of tertiary sandstones differ from one sandstone to another and further characterization is of interest laboratory experiments were conducted to explore the geotechnical characteristics including strength deformational behavior and wetting softening phenomena of more than 13 tertiary sandstones from northern taiwan it was found that these sandstones differ from hard rocks in having significant shear dilation and wetting softening behavior which is defined as the reduction of both strength and stiffness of dry sandstone due to wetting such distinct behavior can occur even when the sandstones have medium to moderate strength based on the degree of wetting softening behavior as well as the deformational behavior two types of sandstones types a and b were identified relative to type a sandstone the type b sandstone is characterized by more deformation shear dilation and more significant wetting softening in addition how the microscopic parameters or petrographic parameters affect the macroscopic mechanical behavior including the deformational behavior uniaxial compressive strength ucs and strength reduction r due to wetting was studied by petrographic analysis among the petrographic and physical parameters evaluated the grain area ratio gar and porosity are found to be the key parameters as a result empirical relations of ucs and strength reduction r due to wetting expressed in terms of porosity and grain area ratio respectively are proposed comparisons were made to sandstones worldwide from published data and it is found that these two empirical relations are also applicable to other sandstones finally a classification method based on ucs and r on the one hand and the petrographic parameters grain area ratio and porosity on the other is proposed for tertiary sandstones to indicate the geotechnical characteristics of sandstones this proposed classification method can also be expressed in terms of grain matrix porosity content of sandstones it is also found that porosity has more influence on the ucs than grain and matrix content does d 2004 elsevier b v all rights reserved

evaluating triggering and causative factors of landslides in lawnon river basin taiwan this study evaluates triggering and causative factors of landslides by comparing their occurrence in the lawnon river basin prior to and after rainfall and earthquake events over a five year period 2005 2009 the landslide ratio in the study area was low less than 4 before 2007 and significantly increased in the wake of typhoon morakot in 2009 the high accumulation of rainfall was the major triggering factor in addition the major seismic activity of march 4 2008 also contributed to landslide occurrence the combined influence of rainfall and the earthquake is evaluated based on multi variable regression analysis though no significant co seismic landslides were found after the march 4 2008 earthquake its influence on slope stability has been observed from the apparent growth of landslide ratio in the four rainfall events following the quake causative factors include the higher landslide ratios occurring in sedimentary rock zones especially sandstone formations with intercalations of shale and dip slopes which are demonstrably prone to plane failures

irregular silica cementation in sandstones and its implication on the usability as building stone abstract palaeocene sandstones outcropping in western spain have long been used for building purposes their use varies considerably in some cities they have been the main stones used in the construction of buildings such as churches and cathedrals zamora whereas in others such as in the historic district of salamanca which has been a world heritage site since 1988 they have been used in the lower part of the town s most striking monuments two cathedrals 12th and 16th centuries the main square 1755 and the house of shells 15th century for protection against erosion and weathering because they are more resistant than the eocene sandstones used for the higher parts of the monuments although in some cases this solution has been successful in others the results have been less satisfactory palaeocene sandstones have an important although irregular silica cement content according to their uniaxial compression strength ucs they may be strong or very strong rocks but under wet conditions some select samples display a significant decrease in their ucs furthermore two types of opal cement can be found one isotropic and the other birefringent the former being the most efficient strength is even higher when isotropic opal cement is found together with alunite kal3 so4 2 oh 6

sensitivity analysis of slug tests part 2 observation wells abstract an earlier paper part 1 this issue dealt with the use of sensitivity analysis for the design of a slug test that would give reasonably accurate estimates of the aquifer parameters by an informed choice of the number and times of measurements an investigation of the radial dependence of the cooper et al analytical solution for a slug test in a confined aquifer shows that the use of one or more observation wells can vastly improve the parameter estimates particularly the estimate of the storage parameter generally the observation well must be fairly close about 10 m or less to the slugged well to be effective the storage coefficient must be small in order to see the effect of the slug at greater distances from the stressed well since the temporal and spatial dependence of the sensitivities for transmissivity and storage are considerably different the addition of one or more observation wells will substantially reduce the correlation between these two parameters which will result in much better estimates than are usually obtained in slug tests these ideas are illustrated using typical data representative of our research sites

geotechnical properties of weak sandstones weak sandstones are here defined as having a saturated uniaxial compression strength of 0 5 20 mpa the mineralogy texture density porosity and saturated moisture content of these materials have

rheological stratification of the lithosphere a direct inference based upon the geodetically observed pattern of the glacial isostatic adjustment of the north american continent 1 a sequence of new analyses of the process of glacial isostatic adjustment gia is described the focus is upon the resolution of a recognized flaw in the currently prevalent model of this process that denoted ice 5g vm2 the flaw concerns a previously noted inability of the model to simultaneously reconcile the vlbi and gps measured rates of vertical and horizontal motion in the region of the north american continent that lay outboard and to the south of the laurentide ice sheet lis at last glacial maximum this characteristic misfit of the model to the data has been suggested to be reconcilable only by recourse to models that explicitly incorporate the influence of lateral viscosity heterogeneity it is demonstrated herein that on the contrary this flaw is entirely and unambiguously attributable to the rheological stratification of the lithosphere an influence not previously accounted for in global models of the gia process but which must exist on a priori grounds

holocene relative sea level changes and glacial isostatic adjustment of the u s atlantic coast the first quality controlled holocene sea level database for the u s atlantic coast has been constructed from 686 sea level indicators the database documents a decreasing rate of relative sea level rsl rise through time with no evidence of sea level being above present in the middle to late holocene the highest rates of rsl rise are found in the mid atlantic region we employ the database to constrain an ensemble of glacial isostatic adjustment models using two ice ice 5g ice 6g global ice sheet reconstructions and two mantle viscosity models vm5a vm5b vm radial variation of viscosity in the sublithospheric mantle variations to assess whether the spherically symmetric viscoelastic models are able to survive intercomparison with a more refined database of postglacial rsl history we identify significant misfits between observations and predictions using ice 5g with the vm5a viscosity profile ice 6g provides some improvement for the northern atlantic region but misfits remain elsewhere decreasing the upper mantle and transition zone viscosity by a factor of 2 to 0 25 10 21 pa s vm5b removes significant discrepancies between observations and predictions along the mid atlantic coastline although misfits remain in the southern atlantic region these may be an indication of the importance of laterally heterogeneous viscosity in the upper mantle

can tilt tests provide correct insight regarding frictional behavior of sliding rock block under seismic excitation earthquake induced dip slope sliding or rock block sliding is usually analyzed using friction angles or friction coefficients measured at the sliding interface a tilt test is a convenient test for measuring the required friction angle however a tilt test is a test under static conditions and the applicability of measured friction parameters to analyze slopes under dynamic excitation requires further discussion this study conducts a static tilt test and a dynamic shaking table test to simulate block sliding with base excitation compares differences in measured sliding thresholds and discusses the cause of these differences tests on three different materials aluminum sandstone and synthetic sandstone show that friction coefficients measured by tilt tests are always larger than the ones derived by shaking table tests moreover high frequency tests yield larger friction coefficients suggesting the sliding threshold is non constant under excitation in addition tests with varying normal stresses on the sliding block show that with increasing contact stresses sliding thresholds decrease implying that sliding threshold varies with normal stress instantaneous friction coefficients i t during sliding are also studied in this work it has been found that frictional behavior of synthetic sandstone deviates from the idealized coulomb friction model the instantaneous friction coefficient varies with relative displacement and relative velocity during sliding finally reasons for differences between a static tilt test and a dynamic shaking table test are discussed this study preliminarily identifies the limitations of the tilt test when applied to dynamic problems and concludes that realistic sliding thresholds can only be obtained using dynamic tests such as shaking table tests

evaluating failure mechanisms of dip slope using a multiscale investigation and discrete element modelling abstract this study proposed an in depth multiscale analysis procedure to identify the dip slope area and assess dip slope stability and influencing area the proposed analysis procedure comprised five stages 1 identifying the potential area of a dip slope 2 analyzing the possible failure types of the dip slope 3 evaluating slope activity 4 analyzing dip slope stability under the influence of possible triggering factors and 5 assessment of the deformation and deposition area to validate the proposed procedure the chaochouhu region of taiwan was analyzed as a dip slope case in stages 1 to 3 the scale of the utilized map and the precision of associated data were evaluated to identify the potential area of a dip slope the possible failure types and the activity of each slope unit in stages 4 and 5 the processes of deformation and sliding in a high activity slope unit were simulated using the discrete element method the numerical model was first verified using in situ monitoring data obtained from inclinometers subsequently the model was used to predict the slope behavior under conditions of wetting deterioration of geomaterial the multiscale analysis revealed comprehensive information regarding the dip slope the application of the proposed approach would be useful to civil engineers for evaluating dip slope stability as well as to relevant authorities for planning hazard mitigation strategies

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

assessment of rock geomechanical quality by quantitative rock fabric coefficients limitations and possible source of misinterpretations abstract rock microfabrics were quantified by image measurement system petrographic image analysis of thin sections along with common measured parameters grain area and size length of major and minor axes and their orientation some quantitative parameters aspect ratio grain boundary smoothness and fabric coefficients micropetrographic quality index k texture coefficient tc indexes of interlocking t and grain size homogeneity g were determined the reliability of these parameters for the evaluation of geomechanical properties was tested on the set of granitic rocks showing pronounced variability in rock mechanical properties none of the tested rock fabric coefficients or parameters proved a close correlation to rock mechanical properties except grain size based on experimental findings the grain size is along with porosity the controlling factor of rock mechanical properties of genetically and mineralogically similar rocks obliteration of the real effects of rock fabric parameters on the mechanical properties of rocks by application of complex fabric coefficients disables their practical use in petrography applied to geomechanics